[Federal Register Volume 78, Number 206 (Thursday, October 24, 2013)]
[Proposed Rules]
[Pages 63574-63625]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-24175]



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Vol. 78

Thursday,

No. 206

October 24, 2013

Part II





Department of the Interior





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Fish and Wildlife Service





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50 CFR Part 17





Endangered and Threatened Wildlife and Plants; Threatened Status for 
Dakota Skipper and Endangered Status for Poweshiek Skipperling; 
Endangered and Threatened Wildlife and Plants; Designation of Critical 
Habitat for Dakota Skipper and Poweshiek Skipperling; Proposed Rules

  Federal Register / Vol. 78 , No. 206 / Thursday, October 24, 2013 / 
Proposed Rules  

[[Page 63574]]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[FWS-R3-ES-2013-0043; 4500030113]
RIN 1018-AY01


Endangered and Threatened Wildlife and Plants; Threatened Status 
for Dakota Skipper and Endangered Status for Poweshiek Skipperling

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service, propose to list the 
Dakota skipper as a threatened species and the Poweshiek skipperling as 
an endangered species under the Endangered Species Act of 1973, as 
amended. If we finalize this rule as proposed, it would extend the 
Act's protections to the Dakota skipper and the Poweshiek skipperling. 
The effect of this regulation is to add the Dakota skipper and the 
Poweshiek skipperling to the List of Endangered and Threatened 
Wildlife. We also propose a special rule under section 4(d) of the Act 
that outlines the prohibitions necessary and advisable for the 
conservation of the Dakota skipper, if it is listed as a threatened 
species.

DATES: Written Comments: We will accept comments received or postmarked 
on or before December 23, 2013. Comments submitted electronically using 
the Federal eRulemaking Portal (see ADDRESSES section, below) must be 
received by 11:59 p.m. Eastern Time on the closing date. We must 
receive requests for public hearings, in writing, at the address shown 
in the ADDRESSES section by December 9, 2013.
    Public Informational Meetings: To better inform the public of the 
implications of the proposed listing and to answer any questions 
regarding this proposed rule, we plan to hold five public informational 
meetings. We have scheduled informational meetings regarding the 
proposed rule in the following locations:
    (1) Minot, North Dakota, on November 5, 2013, at the Souris Valley 
Suites, 800 37th Avenue SW;
    (2) Milbank, South Dakota, on November 6, 2013, at the Milbank 
Chamber of Commerce, 1001 East 4th Avenue;
    (3) Milford, Iowa, on November 7, 2013, at the Iowa Lakeside 
Laboratory, 1838 Highway 86;
    (4) Holly, Michigan, on November 13, 2013, at the Rose Pioneer 
Elementary School, 7110 Milford Road; and
    (5) Berlin, Wisconsin, on November 14, 2013, at the Berlin Public 
Library, 121 West Park Avenue.
    Except for the meeting in Berlin, Wisconsin, each informational 
meeting will be from 5:30 p.m. to 8:00 p.m.; the meeting in Berlin, 
Wisconsin will be from 4:30 p.m. to 7:00 p.m.

ADDRESSES: You may submit comments by one of the following methods:
    (1) Electronically: Go to the Federal eRulemaking Portal: http://www.regulations.gov. In the Search box, enter FWS-R3-ES-2013-0043, 
which is the docket number for this rulemaking. Then, in the Search 
panel on the left side of the screen, under the Document Type heading, 
click on the Proposed Rules link to locate this document. You may 
submit a comment by clicking on ``Comment Now!''
    (2) By hard copy: Submit by U.S. mail or hand-delivery to: Public 
Comments Processing, Attn: FWS-R3-ES-2013-0043; Division of Policy and 
Directives Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax 
Drive, MS 2042-PDM; Arlington, VA 22203.
    We request that you send comments only by the methods described 
above. We will post all comments on http://www.regulations.gov. This 
generally means that we will post any personal information you provide 
us (see the Public Comments section below for more information).

FOR FURTHER INFORMATION CONTACT: Pete Fasbender, Field Supervisor, U.S. 
Fish and Wildlife Service, Twin Cities Ecological Services Office, 4101 
American Boulevard East, Bloomington, Minnesota, 55425, by telephone 
(612) 725-3548 or by facsimile (612) 725-3609. Persons who use a 
telecommunications device for the deaf (TDD) may call the Federal 
Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION: 

Executive Summary

    Why we need to publish a rule. Under the Endangered Species Act 
(Act), if a species is determined to be an endangered or threatened 
species throughout all or a significant portion of its range, we are 
required to promptly publish a proposal in the Federal Register and 
make a determination on our proposal within one year. Listing a species 
as an endangered or threatened species can only be completed by issuing 
a rule. A species may warrant protection through listing under the Act 
if it meets the definition of an endangered or threatened species 
throughout all or a significant portion of its range.
    This rule consists of:
     A proposed rule to list the Poweshiek skipperling as an 
endangered species;
     A proposed rule to list the Dakota skipper as threatened 
species; and
     A proposed special rule under section 4(d) of the Act that 
outlines the prohibitions necessary and advisable for the conservation 
of the Dakota skipper.
    Elsewhere in today's Federal Register, we propose to designate 
critical habitat for the Dakota skipper and Poweshiek skipperling under 
the Act.
    The basis for our action. Under the Act, we can determine that a 
species is an endangered or threatened species based on any of five 
factors: (A) The present or threatened destruction, modification, or 
curtailment of its habitat or range; (B) overutilization for 
commercial, recreational, scientific, or educational purposes; (C) 
disease or predation; (D) the inadequacy of existing regulatory 
mechanisms; or (E) other natural or manmade factors affecting its 
continued existence. Furthermore, whenever a species is listed as a 
threatened species, we may issue regulations that are necessary and 
advisable for the conservation of that species under section 4(d) of 
the Act.
    We have determined the threats to both species include:
     Habitat loss and degradation of native prairies and 
prairie fens, resulting from conversion to agriculture or other 
development; ecological succession and encroachment of invasive species 
and woody vegetation primarily due to lack of management; past and 
present fire, haying, or grazing management that degrades or eliminates 
native prairie grasses and flowering forbs; flooding; and groundwater 
depletion, alteration, and contamination.
     Other natural or manmade factors, including loss of 
genetic diversity, small size and isolation of sites, indiscriminate 
use of herbicides such that it reduces or eliminates nectar sources, 
climate conditions such as drought, and other unknown stressors.
     Existing regulatory mechanisms are inadequate to mitigate 
these threats to both species.
    We will seek peer review. We are seeking comments from 
knowledgeable individuals with scientific expertise to review our 
analysis of the best available science and application of that science 
and to provide any additional scientific information to improve this 
proposed rule. Because we will consider all comments and information 
received during the comment period, our final

[[Page 63575]]

determinations may differ from this proposal.

Information Requested

    We intend that any final action resulting from this proposed rule 
will be based on the best scientific and commercial data available and 
be as accurate and as effective as possible. Therefore, we request 
comments or information from other concerned government agencies, the 
scientific community, industry, or any other interested party 
concerning this proposed rule. We particularly seek comments 
concerning:
    (1) The species' biology, range, and population trends, including:
    (a) Habitat requirements for feeding, breeding, and sheltering;
    (b) Genetics and taxonomy;
    (c) Historical and current range including distribution patterns;
    (d) Historical and current population levels, and current and 
projected trends; and
    (e) Past and ongoing conservation measures for the species, its 
habitat, or both.
    (2) The factors that are the basis for making a listing 
determination for a species under section 4(a) of the Act (16 U.S.C. 
1531 et seq.), which are:
    (a) The present or threatened destruction, modification, or 
curtailment of its habitat or range;
    (b) Overutilization for commercial, recreational, scientific, or 
educational purposes;
    (c) Disease or predation;
    (d) The inadequacy of existing regulatory mechanisms; or
    (e) Other natural or manmade factors affecting its continued 
existence.
    (3) Biological, commercial trade, or other relevant data concerning 
any threats (or lack thereof) to these species and existing regulations 
that may be addressing those threats;
    (4) Additional information concerning the historical and current 
status, range, distribution, and population size of these species, 
including the locations of any additional populations;
    (5) Any information on the biological or ecological requirements of 
these species and ongoing conservation measures for these species and 
their habitat;
    (6) Specific information on the amount and distribution of the 
Dakota skipper and Poweshiek skipperling and their habitat; and
    (7) Our approach to determining the status of each species at each 
site, and our definitions of ``present,'' ``unknown,'' ``possibly 
extirpated,'' and ``extirpated'' as described under Species Status, 
below.
    (8) Suitability of the proposed 4(d) rule for the conservation, 
recovery, and management of the Dakota skipper.
    (9) Whether it would be appropriate to allow routine livestock 
grazing activities on lands inhabited by Dakota skipper in any 
additional counties. The proposed 4(d) rule would allow routine 
livestock grazing activities on lands inhabited by the Dakota skipper 
in counties where the species does not primarily occur in relatively 
flat and moist (wet-mesic or mesic) prairie habitats. Wet-mesic or 
mesic habitats in which the Dakota skipper occurs are typically hayed 
after July 15 and not grazed. We are seeking comments on whether or not 
grazing may be implemented in these habitats in a manner that would 
allow for the persistence of the Dakota skipper.
    (10) Any information on Tribal regulations or Tribal conservation 
efforts that may affect either the Dakota skipper or Poweshiek 
skipperling and their habitat.
    Please include sufficient information with your submission (such as 
scientific journal articles or other publications) to allow us to 
verify any scientific or commercial information you include.
    Please note that submissions merely stating support for or 
opposition to the action under consideration without providing 
supporting information, although noted, will not be considered in 
making a determination, as section 4(b)(1)(A) of the Act directs that 
determinations as to whether any species is a threatened or endangered 
species must be made ``solely on the basis of the best scientific and 
commercial data available.''
    You may submit your comments and materials concerning this proposed 
rule by one of the methods listed in the ADDRESSES section. We request 
that you send comments only by the methods described in the ADDRESSES 
section.
    If you submit information via http://www.regulations.gov, your 
entire submission--including any personal identifying information--will 
be posted on the Web site. If your submission is made via a hardcopy 
that includes personal identifying information, you may request at the 
top of your document that we withhold this information from public 
review. However, we cannot guarantee that we will be able to do so. We 
will post all hardcopy submissions on http://www.regulations.gov. 
Please include sufficient information with your comments (such as 
scientific journal articles or other publications) to allow us to 
verify any scientific or commercial information you include.
    Comments and materials we receive, as well as supporting 
documentation we used in preparing this proposed rule, will be 
available for public inspection on http://www.regulations.gov, or by 
appointment, during normal business hours, at the U.S. Fish and 
Wildlife Service, Twin Cities Ecological Services Office (see FOR 
FURTHER INFORMATION CONTACT).

Previous Federal Actions

    The U.S. Fish and Wildlife Service (Service) initiated proceedings 
to list the Dakota skipper as a threatened species in 1978 (43 FR 
28938), but withdrew the proposed rulemaking after Congress amended the 
Endangered Species Act in 1979 (45 FR 58171). The Dakota skipper was 
designated a category 2 candidate species in the May 22, 1984, Notice 
of Review (49 FR 21664) and remained a category 2 species (January 6, 
1989, 54 FR 572; November 21, 1991, 56 FR 58830; and November 15, 1994, 
59 FR 59020). A category 2 candidate was defined as a species for which 
information in the Service's possession indicates that listing was 
possibly appropriate, but for which sufficient information on 
biological vulnerability and threats was not currently available to 
support a proposal for listing under the Act.
    On January 21, 1994, the Service received a petition from the 
Biodiversity Legal Foundation to list the Dakota skipper as an 
endangered or threatened species and to designate critical habitat. We 
made a 90-day finding that the petition presented substantial 
information to indicate that the requested action may be warranted; the 
finding was published in the Federal Register on July 28, 1994 (59 FR 
38424). On February 27, 1995, we announced a 12-month finding in which 
we determined that the species should remain as a category 2 candidate, 
that timely appropriate prairie management and protection may eliminate 
the need to list the species, and that researchers indicated that more 
surveys, particularly in Minnesota, Iowa, and North Dakota, were needed 
(60 FR 10535).
    In a December 5, 1996 (61 FR 64481) decision, the Service 
discontinued the practice of maintaining a list of species regarded as 
``category-2 candidates.'' Instead, the Service would keep a single 
list of candidate species--species for which the Service has on file 
sufficient information to support issuance of a proposed listing rule.
    In 2002, the Service reviewed the status of the Dakota skipper and 
determined that it met the definition of a candidate species. The 
Dakota skipper was assigned a listing priority number of 11 on June 13, 
2002 (67 FR 40657).

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The Dakota skipper remained a candidate species with a listing priority 
number of 11 in subsequent notices, including May 4, 2004 (69 FR 
24876), May 11, 2005 (70 FR 24870), and September 12, 2006 (71 FR 
53756). The Service changed the listing priority from 11 to 8 on 
December 6, 2007 (72 FR 69034), and the Dakota skipper remained a 
candidate species with a listing priority number of 8 in subsequent 
notices, including December 10, 2008 (73 FR 75176), November 9, 2009 
(74 FR 57804), November 10, 2010 (75 FR 69222), and October 26, 2011 
(76 FR 66370).
    On May 12, 2003, the Service received a petition from the 
Biodiversity Conservation Alliance and five others to list the Dakota 
skipper as endangered or threatened and to designate critical habitat. 
The Service agreed with the petitioners, by virtue of having made it a 
candidate in 2002, that the Dakota skipper warranted listing as 
threatened or endangered under the Act. The petition did not contain 
evidence supporting emergency listing or changing the listing priority 
number; therefore, the Service took no further action on the petition.
    On July 12, 2011, the Service filed a proposed settlement agreement 
with the Center for Biological Diversity in a consolidated case in the 
U.S. District Court for the District of Columbia. The settlement 
agreement was approved by the court on September 9, 2011. As part of 
this settlement agreement, the Service agreed to complete a proposed 
listing rule or not warranted finding for the Dakota skipper by 
September 30, 2013.
    The Service identified the Poweshiek skipperling (Oarisma 
poweshiek) as a candidate species, with a listing priority number of 2, 
in a notice of review published in the Federal Register on October 26, 
2011 (76 FR 66370).

Status Assessments for Dakota Skipper and Poweshiek Skipperling

Background

Dakota Skipper
Species Description
    The Dakota skipper (Hesperia dacotae) is a member of the skipper 
family Hesperiidae and was first described in 1911 from collections 
taken at Volga, South Dakota, and Grinnell, Iowa (Skinner 1911 in Royer 
and Marrone 1992a, p. 1). The family Hesperiidae includes 3 other 
subfamilies, and the genus Hesperia contains 18 species (Miller and 
Brown 1981, p. 31; Ferris 1989 in Royer and Marrone 1992a, p. 1). 
Dakota skipper is the accepted common name for H. dacotae.
    The Dakota skipper is a small to medium-sized butterfly with a 
wingspan of 2.4-3.2 centimeters (cm) (0.9-1.3 inches (in)) and hooked 
antennae (Royer and Marrone 1992a, p. 3). Like other Hesperiidae 
species, Dakota skippers have a faster and more powerful flight than 
most butterflies because of a thick, well-muscled thorax (Scott 1986, 
p. 415).
    Adult Dakota skippers have variable markings. The dorsal surface of 
adult male wings ranges in color from tawny-orange to brown and has a 
prominent mark on the forewing; the ventral surface is dusty yellow-
orange (Royer and Marrone 1992a, p. 3). The dorsal surface of adult 
females is darker brown with diffused tawny orange spots and a few 
diffused white spots restricted to the margin of the forewing; the 
ventral surfaces are dusty gray-brown with a faint white spotband 
across the middle of the wing (Royer and Marrone 1992a, p. 3). Adult 
Dakota skippers may be confused with the Ottoe skipper (H. ottoe), 
which is somewhat larger with slightly longer wings (Royer and Marrone 
1992a, p. 3). Dakota skipper pupae are reddish-brown, and the larvae 
are light brown with a black collar and dark brown head (McCabe 1981, 
p. 181).
General Life History
    Dakota skippers are univoltine (having a single flight per year), 
with an adult flight period that may occur from the middle of June 
through the end of July (McCabe 1979, p. 6; McCabe 1981, p. 180; Dana 
1991, p. 1; Royer and Marrone 1992a, p. 26; Skadsen 1997, p. 3; Swengel 
and Swengel 1999, p. 282). The actual flight period varies somewhat 
across the range of each species and can also vary significantly from 
year-to-year, depending on weather patterns. Females emerge slightly 
later than males (Dana 1991, p. 1), and the observed sex ratio of 
Dakota skippers was roughly equal during peak flight periods (Dana 
1991, p. 15; Swengel and Swengel 1999, pp. 274, 283).
    The Dakota skipper flight period in a locality lasts two to four 
weeks, and mating occurs throughout this period (Braker 1985, p. 46; 
McCabe and Post 1977a, p. 38; McCabe and Post 1977b, p. 36; McCabe 
1979, p. 6; McCabe 1981, p. 180; Dana 1991, p. 15; Swengel and Swengel 
1999, p. 282). Adult male Dakota skippers exhibit perching behavior 
(perch on tall plants to search for females), but occasionally appear 
to patrol in search of mating opportunities (Royer and Marrone 1992a, 
p. 25).
    Dakota skippers lay eggs on broadleaf plants (McCabe 1981, p. 180) 
and grasses (Dana 1991, p. 17), although larvae feed only on grasses. 
Potential lifetime fecundity is between 180 and 250 eggs per female 
Dakota skipper; realized fecundity depends upon longevity (Dana 1991, 
p. 26). Female Dakota skippers lay eggs daily in diminishing numbers as 
they age (Dana 1991, pp. 25-26). Dana (1991, p. 32) estimated the 
potential adult life span of Dakota skipper to be 3 weeks and the 
average life span (or residence on site before death or emigration) to 
be 3 to 10 days on one Minnesota prairie.
    Dakota skippers overwinter as larvae and complete one generation 
per year. Dakota skipper eggs hatch after incubating for 7-20 days; 
therefore, hatching is likely completed before the end of July. After 
hatching, Dakota skipper larvae crawl to the bases of grass plants 
where they form shelters at or below the ground surface with silk, 
fastened together with plant tissue (Dana 1991, p. 16). They construct 
2-3 successively larger shelters as they grow (Dana 1991, p. 16). The 
larvae emerge from their shelters at night to forage (McCabe 1979, p. 
6; McCabe 1981, p. 181; Royer and Marrone 1992a, p. 25) and appear to 
clip blades of grass and bring them back to their shelters to consume 
(Dana 2012a, pers. comm.).
    Dakota skippers have six or seven larval stages (instars) (Dana 
1991, pp. 14-15) and overwinter (diapause) in ground-level or 
subsurface shelters during either the fourth or fifth instar (McCabe 
1979, p. 6; McCabe 1981, pp. 180, 189; Dana 1991, p. 15; Royer and 
Marrone 1992a, pp. 25-26). In the spring, larvae resume feeding and 
undergo two additional molts before they pupate. During the last two 
instars, larvae shift from buried shelters to horizontal shelters at 
the soil surface (Dana 1991, p. 16).
Food and Water
    Nectar and water sources for adult Dakota skippers vary regionally 
and include purple coneflower (Echinacea angustifolia), bluebell 
bellflower (Campanula rotundifolia), white prairie clover (Dalea 
candida), upright prairie coneflower (Ratibida columnifera), fleabanes 
(Erigeron spp.), blanketflowers (Gaillardia spp.), black-eyed Susan 
(Rudbeckia hirta), groundplum milkvetch (Astragalus crassicarpus), and 
yellow sundrops (Calylophus serrulatus) (McCabe and Post 1977b, p. 36; 
Royer and Marrone 1992a, p. 21). Plant species likely vary in their 
value as nectar sources due to the amount of nectar available during 
the adult flight period (Dana 1991, p. 48). Swengel and

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Swengel (1999, pp. 280-281) observed nectaring at 25 plant species, but 
85 percent of the nectaring was at the following three plants, in 
declining order of frequency: Purple coneflower, blanketflower, and 
groundplum milkvetch. Dana (1991, p. 21) reported the use of 25 nectar 
species in Minnesota with purple coneflower most frequented; McCabe 
(1979, p. 42, McCabe 1981, p. 187) observed Dakota skippers using eight 
nectar plants. In addition to nutrition, the nectar of flowering forbs 
provides water for Dakota skipper, which is necessary to avoid 
desiccation during flight activity (Dana 1991, p. 47; Dana 2013, pers. 
comm.).
    Dakota skipper larvae feed only on several native grass species; 
little bluestem (Schizachyrium scoparium) is a frequent food source of 
the larvae (Dana 1991, p. 17; Royer and Marrone 1992a, p. 25), although 
they have been found on Panicum spp., Poa spp., and other native 
grasses (Royer and Marrone 1992a, p. 25). Seasonal senescence patterns 
of grasses relative to the larval period of Dakota skippers are likely 
important in determining the suitability of grass species as larval 
host plants. Large leaf blades, leaf hairs, and the distance from 
larval ground shelters to palatable leaf parts preclude the value of 
big bluestem and Indian grass as larval food plants (Dana 1991, p. 46).
Dispersal
    Dakota skipper are not known to disperse widely; the species was 
evaluated among 291 butterfly species in Canada as having relatively 
low mobility. Experts estimated Dakota skipper to have a mean mobility 
of 3.5 (standard deviation = 0.7) on a scale of 0 (sedentary) to 10 
(highly mobile) (Burke et al. 2011, p. 2279; Fitzsimmons 2012, pers. 
comm.). Dakota skippers may be incapable of moving greater than 1 
kilometer (km) (0.6 miles (mi)) between patches of prairie habitat 
separated by structurally similar habitats (e.g., crop fields, grass-
dominated fields or pasture, but not necessarily native prairie) 
(Cochrane and Delphey 2002, p. 6). Royer and Marrone (1992a, p. 25) 
concluded that Dakota skippers are not inclined to disperse, although 
they did not describe individual ranges or dispersal distances. McCabe 
(1979, p. 9; 1981, p. 186) found that concentrated activity areas for 
Dakota skippers shift annually in response to local nectar sources and 
disturbance.
    In a mark-recapture study, average adult movements of Dakota 
skipper were less than 300 meters (m) (984 feet (ft)) over 3-7 days; 
marked adults crossed less than 200 m (656 ft) of unsuitable habitat 
between two prairie patches and moved along ridges more frequently than 
across valleys (Dana 1991, pp. 38-40). Dana (1997, p. 5) later observed 
reduced movement rates across a small valley with roads and crop fields 
compared with movements in adjacent widespread prairie habitat. Skadsen 
(1999, p. 2) reported possible movement of Dakota skippers in 1998 from 
a known population at least 800 m (2625 ft) away to a site with an 
unusually heavy growth of purple coneflower; he had not found Dakota 
skippers in three previous years when coneflower production was sparse. 
The two sites were connected by native vegetation of varying quality, 
interspersed by a few asphalt and gravel roads (Skadsen 2001, pers. 
comm.).
    In summary, dispersal of Dakota skipper is very limited due in part 
to its short adult life span and single annual flight. Therefore, the 
species' extirpation from a site is likely permanent unless it is 
within about 1 km (0.6 mi) of a site that generates a sufficient number 
of emigrants or is artificially reintroduced to a site; however, the 
capability to propagate the Dakota skipper is currently lacking.
Habitat
    Dakota skippers are obligate residents of undisturbed (remnant, 
untilled) high-quality prairie, ranging from wet-mesic tallgrass 
prairie to dry-mesic mixed-grass prairie (Royer and Marrone 1992a, pp. 
8, 21). High-quality prairie contains a high diversity of native plant 
species, including flowering herbaceous plants (forbs). Royer and 
Marrone (1992a, p. 21) categorized Dakota skipper habitat into two main 
types that were once intermixed on a landscape scale, but are now 
mostly segregated. The first, referred to as ``Type A'' by Royer et al. 
(2008, pp. 14-16), is low wet-mesic prairie that occurs on near-shore 
glacial lake deposits. Type A Dakota skipper habitat is dominated by 
bluestem grasses, with three other plant species almost always present 
and blooming during Dakota skipper's flight period: Wood lily (Lilium 
philadelphicum), bluebell bellflower, and mountain deathcamas (smooth 
camas; Zigadenus elegans) (McCabe 1981, p. 190). This habitat type has 
a high water table and is subject to intermittent flooding in the 
spring, but provides ``sufficient relief to provide segments of non-
inundated habitat during the spring larval growth period within any 
single season'' (Royer et al. 2008, p. 15). Common forbs in bloom 
during the late season in Type A habitat include Rocky Mountain blazing 
star (Liatris ligulistylis), Canada goldenrod (Solidago canadensis), 
strict blue-eyed grass (Sisyrinchium montanum), common goldstar 
(Hypoxis hirsuta), and black-eyed Susan (Lenz 1999a, p. 6). Type A 
habitats also contain small patches of dry-mesic prairie inhabited by 
Dakota skippers. Common forb species in these dry-mesic areas include 
stiff sunflower (Helianthus pauciflorus Nutt. ssp. pauciflorus), and 
candle anenome (Anemone cylindrica), although purple coneflower was 
rare in these habitats (Lenz 1999a, pp. 6-11). Dakota skipper inhabits 
Type A habitat in north-central North Dakota, southeast North Dakota, 
and Manitoba.
    The second Dakota skipper habitat type, referred to as ``Type B'' 
by Royer et al. (2008, p. 14), occurs on rolling terrain over gravelly 
glacial moraine deposits and is dominated by bluestems and needle 
grasses (Heterostipa spp.). As with Type A habitat, bluebell bellflower 
and wood lily are also present in Type B habitats, but Type B habitats 
also support more extensive stands of purple coneflower, upright 
prairie coneflower, and common gaillardia (Gaillardia aristata) (Royer 
and Marrone 1992a, p. 22). Both Type A and Type B prairies may contain 
slightly depressional (low topographical areas that allow for the 
collection of surface water) wetlands with extensive flat areas and 
slightly convex hummocks, which are dryer than the wet areas (Lenz 
1999b, pp. 4, 8).
    In northeastern South Dakota, Dakota skippers inhabit primarily 
Type B habitats with abundant purple coneflower, but they also occur in 
nearby Type A habitats in some areas (Skadsen 1997, p. 4). All Type A 
habitats occupied by Dakota skipper in South Dakota are near hill 
prairie (Type B) habitats that are managed with fall haying (Skadsen 
2006b, p. 2).
    Little bluestem and porcupine grass are the predominant grass 
species in Dakota skipper habitat in South Dakota (Skadsen 2006b, p. 
2). Dry-mesic prairies suitable for Dakota skippers in South Dakota 
typically include little bluestem, side oats grama, porcupine grass, 
needle-and-thread grass (H. comata), and prairie dropseed, and a high 
diversity and abundance of forbs, including purple coneflower, purple 
prairie clover (Dalea purpurea), white prairie clover, yellow sundrops, 
prairie groundsel (Packera plattensis), groundplum milkvetch, eastern 
pasqueflower (Pulsatilla patens), old man's whiskers (prairie smoke, 
Geum triflorum), western silver aster (Symphyotrichum sericeum), dotted 
blazing star (Liatris punctata), tall blazing star (L. asper), meadow 
zizia

[[Page 63578]]

(Zizia aptera), blanket flower (Gaillardia sp.), prairie sagewort 
(Artemisia frigida), and leadplant (Amorpha canescens) (Skadsen 2006b, 
pp. 1-2). Purple coneflower occurs at all sites where the Dakota 
skipper has been recorded in South Dakota, although it is absent at 
some sites where Dakota skipper is abundant in other states (Skadsen 
2006b, p. 2).
    In Minnesota, Dakota skippers inhabit Type B habitats. Dana (1997, 
p. 8) described typical habitat in Minnesota as dry-mesic prairie 
dominated by mid-height grasses with an abundance of nectar sources 
including purple coneflower and prairie milkvetch (Astragalus laxmannii 
Jacq. var. robustior). Southern dry prairies in Minnesota are described 
as having sparse shrub cover (less than 5 percent) composed primarily 
of leadplant, with prairie rose (Rosa arkansana), wormwood sage, or 
smooth sumac (Rhus glabra) present and few, if any, trees (Minnesota 
DNR 2012a). Dana (1991, p. 21) never encountered Dakota skippers in wet 
or wet-mesic prairies in Minnesota, despite abundance of suitable 
plants and the frequent use of these habitats by similar skipper 
species. In systematic surveys at twelve Minnesota sites, Swengel and 
Swengel (1999, pp. 278-279) found that Dakota skippers were 
significantly more abundant on dry prairie than on either wet-mesic 
prairie. In Manitoba, Dakota skippers inhabit Type A habitats, occupy 
the slightly higher, drier areas of wet-mesic prairie where nectar 
sources are more abundant (Webster 2003, p. 7). Occupied habitats in 
Saskatchewan are similar to the drier upland dry-mesic mixed-grass 
prairie hillside habitats in Manitoba, which is dominated by bluestems 
and needlegrass. The Dakota skipper was most common on ridgetops and 
hillsides near purple coneflower (Webster 2003, p. 8).
    In North Dakota, an association of bluestems (Schizachyrium 
scoparium, Andropogon gerardii) and needlegrasses, typically invaded by 
Kentucky bluegrass (Poa pratensis), typifies dry-mesic Dakota skipper 
habitat in the rolling terrain of river valleys and the Missouri Coteau 
(Royer and Marrone 1992a, p. 22). These prairies, located on the 
western edge of the species' known range, typically contain wood lily, 
bluebell bellflower, coneflowers, and other asters as nectar sources; 
in some areas, mountain deathcamas also occurs (Royer and Marrone 
1992a, p. 22). The location of larval food plants rarely seems to 
affect Dakota skipper distribution within habitats because these warm-
season grasses are usually dominant and evenly dispersed (Swengel 1994, 
p. 6), although invasion by smooth brome grass (Bromus inermis) and 
other invasive species may displace or extirpate native larval food 
plants (Culliney 2005, p. 134, Bahm et al. 2011, p. 240, LaBar and 
Schultz 2012, p. 177).
    Two key factors, soils unsuitable for agriculture and steep 
topography, have allowed remnant native prairie habitats inhabited by 
Dakota skippers to persist (Royer and Marrone 1992a, p. 22). McCabe 
(1979, pp. 17-18; 1981, p. 192) and Royer et al. (2008, p. 16) have 
linked the historical distribution of Dakota skippers to surface 
geological features and soils that are glacial in origin and, possibly, 
regional precipitation-evaporation ratios (ratio of evaporation 
occurring naturally in one location over a given area compared to the 
amount of precipitation, such as rain and snow, falling over the same 
area). Soil types typical of Dakota skipper sites were described as 
sandy loams, loamy sand, or loams (Lord 1988 in Royer et al. 2008, pp. 
3, 10). Additional edaphic (soil) features, such as soil moisture, 
compaction, surface temperature, pH, and humidity, may be contributing 
factors in larval survival and, thus, important limiting factors for 
Dakota skipper populations (Royer et al. 2008, p. 2). For example, 
edaphic parameters measured in sites throughout the range of Dakota 
skipper included a bulk density (an indicator of soil compaction) that 
ranged from 0.9g/cm\3\ to 1.3 g/cm\3\ and mean soil pH that ranged from 
6.3 to 6.7 with high micro-scale variation (variation on a small scale) 
(Royer et al. 2008, p. 10). Soil texture ranged from 4 to 12 percent 
clay, 53 to 74 percent sand, and 14 to 39 percent silt (Royer et al. 
2008, p. 12). Seasonal soil temperatures, measured at three depths (20, 
40, and 60 cm (8, 16, and 24 in)) were the same at all depths within a 
site; Minnesota sites generally had higher soil temperatures at all 
depths than sites in North Dakota or South Dakota (Royer et al. 2008, 
p. 11).
    Dakota skipper larvae are particularly vulnerable to desiccation 
(drying out) during dry summer months and require ``vertical water 
distribution'' (movement of shallow groundwater to the soil surface) in 
the soils or wet low areas to provide relief from high summer 
temperatures (Royer et al. 2008, pp. 2, 16). Humidity may also be 
essential for larval survival during winter months since the larvae 
cannot take in water during that time and depend on humid air to 
minimize water loss through respiration (Dana 2013, pers. comm.). Royer 
(2008, pp. 14-15) measured microclimalogical levels (climate in a small 
space, such as at or near the soil surface) within ``larval nesting 
zones'' (between the soil surface and 2 cm deep) throughout the range 
of Dakota skippers, and found an acceptable rangewide seasonal (summer) 
mean temperature range of 18 to 21[deg]C (64 to 70 [deg]F), rangewide 
seasonal mean dew point ranging from 14 to 17 [deg]C (57 to 63 [deg]F), 
and rangewide seasonal mean relative humidity between 73 and 85 
percent.
Species Occupancy
    We generally consider the Dakota skipper or Poweshiek skipperling 
to be ``present'' at sites where the species was detected during the 
most recent survey, if the survey was conducted in 2002 or more 
recently and there is no evidence to suggest the species is now 
extirpated from the site, (e.g., no destruction or obvious and 
significant degradation of the species' habitat), with the exception of 
the following five sites. We consider the species to be present at one 
Poweshiek skipperling site in Michigan where the species was observed 
at the site in 1996 and no further surveys have been conducted. This 
site, however, still has suitable habitat for the species according to 
species experts in the State and at least one other species of prairie 
fen dependent butterfly is present (Hosler 2013, pers. comm.). 
Therefore, the Poweshiek skipperling is most likely still present at 
this site. We also consider the species to be present at one Dakota 
skipper site (Frenchman's Bluff Preserve in Minnesota) where the most 
recent survey was from 1993. At this site, no evidence suggests the 
species is not still present because, based on a species-expert review 
of the site, the habitat and management is still conducive to the 
species. Additional sites where we consider Dakota skipper to be 
present include two sites in Minnesota with 1996 records (Bluestem 
Prairie and Buffalo River State Park) and one site with a 1998 record 
(an unnamed site in North Dakota). Although no survey for the species 
has taken place at Bluestem Prairie since 1996, a 2012 assessment of 
the habitat at the site indicates that this site is a high-quality 
prairie that contains the native prairie flora conducive to the Dakota 
skipper (Selby 2012, p. 9). The site at Buffalo River State park, which 
adjoins Bluestem Prairie, has not been surveyed since 1996 but recent 
habitat assessments show that it still contains prairie habitats with 
the native prairie flora conducive to the species (MN DNR 2013, 
unpubl.). Furthermore, the species expert in Minnesota supports that 
the species is most likely still present at these sites. Little 
information is known about the one unnamed site in North

[[Page 63579]]

Dakota; however, the best information we have indicates that the 
habitat is still suitable for the species, and the North Dakota species 
expert supports that the species is likely present.
    We assigned a status of ``unknown'' if the species was found in 
1993 or more recently, but not in the most recent one to two sequential 
survey year(s) since 1993 and there is no evidence to suggest the 
species is now extirpated from the site (e.g., no destruction or 
obvious and significant degradation of the species' habitat). We 
considered a species is to be ``possibly extirpated'' at sites where it 
was detected at least once prior to 1993, but not in the most recent 
one to two sequential survey years(s). A species is also considered 
``possibly extirpated'' at sites where it was found prior to 1993 and 
no surveys have been conducted in 1993 or more recently. At least three 
sequential years of negative surveys were necessary for us to consider 
the species ``extirpated'' from a site, because of the difficulty of 
detecting these species, as explained further in this section. A 
species is also considered ``extirpated'' at sites where habitat for 
the species is no longer present.
    When determining whether the species occupancy is unknown, possibly 
extirpated, or extirpated at a particular site, we used the survey year 
1993 as a cut-off date, because most known sites (more than 75 percent 
of known Poweshiek skipperling sites and over 89 percent of known 
Dakota skipper sites) have been surveyed at least once since 1993 and 
survey data more than 20 years old may not reflect the current status 
of a species or its habitat at a site (for example, due to habitat loss 
from secondary succession of woody vegetation or a change in plant 
communities due to invasive species). Although it cannot be presumed 
that the species is absent at sites not surveyed since 1993, the 
likelihood of occupancy of these sites should be considered differently 
than sites with more recent survey data (e.g., due to woody vegetation 
succession over time). When analyzing survey results, we disregarded 
negative surveys conducted outside of the species' flight period or 
under unsuitable conditions (e.g., high wind speeds).
    After we applied these standards to initially ascertain the status 
of the species, we asked species experts and Service personnel to help 
verify, modify, or correct species' occupancy at each site 
(particularly for sites with questionable habitat quality or those that 
have not been surveyed recently). In most cases, we used the status 
confirmed during expert review, unless we received additional 
information (e.g., additional survey or habitat data provided after the 
expert reviews) that suggests a different status at a particular site.
    Timing of surveys is based on initial field checks of nectar plant 
blooms and sightings of butterfly species with synchronous emergence 
(sightings of butterfly species that emerge at the same time as Dakota 
skipper and Poweshiek skipperling), and, more recently, emergence 
estimated by a degree-day emergence model using high and low daily 
temperature data from weather stations near the survey sites (Selby, 
undated, unpublished dissertation). Surveys are conducted during flight 
periods when the species' abundance is expected to be at levels at 
which the species can be detected. However, as with many rare species, 
detection probabilities are imperfect and some uncertainty remains 
between non-detection and true absence (Gross et al. 2007, pp. 192, 
197-198; Pellet 2008, pp. 155-156). Three sequential years of negative 
surveys is sufficient to capture variable detection probabilities, 
since each survey year typically encompasses more than one visit (e.g., 
the average number of visits per Dakota skipper site per year ranges 
from 1 to 11) and the probability of false absence after 5-6 visits 
drops below 5 percent for studied butterfly species with varying 
average detection probabilities (Pellet 2008, p. 159). Therefore, the 
site is considered ``extirpated'' if there are three sequential years 
of negative surveys.
    It cannot be presumed that the species is not persisting at a site 
only because there have not been recent surveys. At several sites, the 
species has persisted for longer than 20 years; for example, Dakota 
skipper was first recorded at Scarlet Fawn Prairie in South Dakota in 
1985 and has had positive detections every survey since that date--the 
most recent detection was in 2012. The year 1993 was chosen based on 
habitat-related inferences, specifically, the estimated time for 
prairie habitat to degrade to non-habitat due to woody encroachment and 
invasive species. For example, native prairies with previous light-
grazing management that were subsequently left idle transitioned from 
mixed grass to a mix of woody vegetation and mixed grass in 13 years 
and it was predicted that these idle prairies would be completely lost 
due to woody succession in a 30-year timeframe (Penfound 1964, pp. 260-
261). The time for succession of idle prairie depends on numerous 
factors, such as the size of the site, edge effects (the changes that 
occur on the boundary of two habitat types), and the plant composition 
of adjacent areas.
    This approach is the most objective way to evaluate the data range-
wide. Most sites have been surveyed over multiple years, although the 
frequency and type of surveys varied among sites and years. In several 
cases, species experts provided input on occupancy based on their 
familiarity with the habitat quality and stressors to populations at 
particular sites.
    To summarize, there are few sites with relatively older data where 
we consider the species to still be present. In general, most sites 
with a present status have had a positive detection in 2002, or more 
recently with a few exceptions. At one Poweshiek skipperling site, the 
species was observed at the site in 1996, and no further surveys have 
been conducted. The remaining Poweshiek skipperling sites where the 
species is considered present have had detections in 2012, except one 
site where the species was detected in 2011 and no further surveys have 
occurred. Likewise, at four Dakota skipper sites we consider the 
species to be present with the most recent record from 2001 or earlier 
including one site where the most recent survey was from 1993, two 
sites with 1996 records, and one site with a 1998 record. No evidence 
suggests that the species is not still present at these sites because 
the best information indicates that the site's habitat is still 
conducive to the butterfly, and, therefore, the species may still be 
present there. We also consider Dakota skipper to be present at the 
following sites: 20 sites in Canada that were surveyed only once in 
2002; 1 additional site with a 2002 detection of the species and a 
favorable habitat assessment in 2012; 1 site with a 2003 detection; 1 
site with a 2005 detection; 2 sites with a 2006 detection; 25 sites in 
Canada that were surveyed only once in 2007; 1 additional site with a 
2007 detection; 7 sites with a positive detection in 2008; 2 sites with 
a positive detection in 2009; and 27 sites with positive detections in 
2012.
Population Distribution and Occupancy Status
    Once found in native prairies in five states and two Canadian 
provinces, the Dakota skipper and its habitat have undergone dramatic 
declines; the species is now limited to native prairie remnants in 
three states and two Canadian provinces. The Dakota skipper is presumed 
extirpated from Illinois and Iowa and no longer occurs east of western 
Minnesota--an approximately 690-kilometer (km) (430-mile) reduction of 
its range. Populations persist in

[[Page 63580]]

western Minnesota, northeastern South Dakota, North Dakota, southern 
Manitoba, and southeastern Saskatchewan. Royer and Marrone (1992a, p. 
5) stated that Dakota skippers may also occur in far eastern Montana 
and southeastern Saskatchewan, in habitats similar to those occupied by 
the species in northwestern North Dakota. The Dakota skipper was 
subsequently found in Saskatchewan in 2001 after 40 years of searching 
(Hooper 2002, pers. comm.), but Royer (2002, pers. comm.) no longer 
thinks that the species occurs in Montana.
    From its earliest identification, the Dakota skipper was considered 
rare (Royer and Marrone 1992a, p. 1), although considerable destruction 
of its habitat likely occurred even before the species was first 
described in 1911. Habitat destruction and degradation has greatly 
fragmented Dakota skipper's range from its core through its northern 
and western fringes (McCabe 1981, p. 179; Royer and Marrone 1992a, p. 
28; Schlicht and Saunders 1994, p. 1; Royer 1997, p. 2; Schlicht 1997a, 
p. 2; Schlicht 1997b, p. 2; Skadsen 1997, pp. 25-26; Skadsen 1999, p. 
15; Swengel and Swengel 1999, p. 267). The historical distribution of 
Dakota skippers may never be precisely known because ``much of 
tallgrass prairie was extirpated prior to extensive ecological study'' 
(Steinauer and Collins 1994, p. 42), such as butterfly surveys. 
Destruction of tallgrass and mixed-grass prairie began in 1830 (Samson 
and Knopf 1994, p. 418), but significant documentation of the 
ecosystem's butterfly fauna did not begin until about 1960. Therefore, 
most of the species' decline probably went unrecorded. Based on records 
of vouchered specimens, however, we know that Dakota skipper range has 
contracted northward out of Illinois and Iowa. The species was last 
recorded in Illinois in 1888 (McCabe 1981, p. 191) and in Iowa in 1992 
(Orwig and Schlicht 1999, p. 6). Britten and Glasford's (2002, pp. 363, 
372) genetic analyses support the presumption that this species 
formerly had a relatively continuous distribution; the small genetic 
divergence (genetic distance) among seven sites in Minnesota and South 
Dakota indicate that populations there were once connected. Dakota 
skipper dispersal is very limited due in part to its short adult life 
span and single annual flight. Therefore, the species' extirpation from 
a site is likely permanent unless it is within about 1 km (0.62 mi) of 
a site that generates a sufficient number of emigrants or is 
artificially reintroduced to a site.
    The Dakota skipper's range once comprised native prairie in five 
states and Canada, extending from Illinois to Saskatchewan; it now 
occurs only in native prairie remnants in portions of three states and 
two Canadian provinces. Of the 259 historically documented sites, there 
are 91 sites where we consider the Dakota skipper to be present, 81 
sites with unknown status, 40 possibly extirpated sites, and 47 that 
are considered extirpated (Table 1). Approximately half (45 of 91) of 
the sites where the species is considered to be present are located in 
Canada, mostly within three isolated complexes, and were observed in 
either 2002 or 2007 with no subsequent surveys. The remaining 46 sites 
where the species is considered to be present are about equally 
distributed among Minnesota (14 sites), North Dakota (18 sites), and 
South Dakota (14 sites). Researchers made positive detections of the 
species in 27 of these sites in 2012. Other sites with a present status 
with relatively older positive detections and no subsequent surveys for 
the species include 2 sites with positive detections in 1996, one site 
with a positive detection in 1998, one site with a positive detection 
in 2002, one site with a positive detection in 2003, one site with a 
positive detection in 2005, 2 sites with a positive detection in 2006, 
one site with a positive detection in 2007, 7 sites with a positive 
detection in 2008, and 2 sites with a positive detection in 2009. At 
several of these sites, the habitat has been assessed more recently 
than they were surveyed for the species. The distribution and status of 
Dakota skipper in each state of known historical or extant occurrence 
are described in detail below.

 Table 1--Number of Historically Documented Dakota Skipper Sites Within Each State and the Number of Sites Where
                the Species Is Thought To Be Present, Unknown, Possibly Extirpated, or Extirpated
----------------------------------------------------------------------------------------------------------------
                                                                                                      Percent of
                                                                                                        total
                                                           Possibly                                   number of
            State               Present      Unknown      extirpated      Extirpated       Total      historical
                                                                                                       sites by
                                                                                                        state
----------------------------------------------------------------------------------------------------------------
Illinois....................  ...........  ...........  ..............               1            1          0.4
Iowa........................  ...........  ...........  ..............               3            3            1
Minnesota...................           14           22              18              12           66           26
North Dakota................           18           13              10              13           54           21
South Dakota................           14           46              10              15           85           33
Manitoba....................           31            0               2               3           36           14
Saskatchewan................           14            0               0               0           14            5
                             -----------------------------------------------------------------------------------
    Total Number of                    91           81              40              47          259  ...........
     Historically Documented
     Sites..................
                             -----------------------------------------------------------------------------------
    Percent of the Total               35           31              16              18  ...........          100
     Number of Historical
     Sites by Occupancy.....
----------------------------------------------------------------------------------------------------------------

Illinois
    Dakota skippers are considered to be extirpated from Illinois. The 
species was last recorded near Chicago in 1888 (McCabe 1981, p. 191).
Iowa
    There are three historical records of Dakota skippers in three 
counties in Iowa (Dickinson, Poweshiek, and Woodbury), but the species 
is presumed extirpated from the State (Schlicht and Orwig 1998, pp. 84-
85; Selby 2004a, pp. 1, 5; Selby 2012, pers. comm.; Nekola and Schlicht 
2007, p. 9). The species was last seen at Cayler Prairie (Dickinson 
County) in 1992, but surveys of this site in 2000, 2004, 2005, and 2007 
were negative, so we presume it to be extirpated from that site 
(Schlicht and Orwig 1998, p. 85; Selby 2004a, p. 5; Selby 2006a, p. 5; 
Selby 2008, p. 6).

[[Page 63581]]

The species was not observed at eight sites surveyed between 1988-1997 
(Swengel and Swengel 1999, pp. 288-289), at eight sites surveyed in 
2004 (Selby 2004a, p. 5), nor during extensive surveys at 32 sites in 
2007 (Selby 2008, p. 6).
Minnesota
    Minnesota historically contained about 26 percent of the sites 
where the Dakota skipper has been recorded (Table 1) (Service 2013, 
unpubl. geodatabase). Since the earliest known record (1965) of the 
species in Minnesota, 66 sites have been recorded in the State, but 
recent surveys indicate that the species is declining in the State 
(Service 2013, unpubl. geodatabase). Of the 66 known locations of 
Dakota skipper in Minnesota; the species is extirpated or possibly 
extirpated from 30 of those sites and the status is unknown at 22 
others (Service 2013, unpubl. geodatabase). Dakota skipper is 
considered to be present at 14 sites in Minnesota in 6 counties: Clay, 
Lincoln, Murray, Norman, Pipestone, and Pope, although 2 of those sites 
have not been surveyed since 1996 and 1 site has not been surveyed 
since 1993.
    McCabe (1981, p. 187) observed very stable population numbers in 
Minnesota prairies that he visited repeatedly from 1968-1979. On dry-
mesic prairie in Lincoln County, Minnesota, Dana (Dana 1997, pp. 3-5) 
also observed stable numbers into the thousands during his intensive 
studies from 1978 to 1983. Schlicht (1997a, p. 13) and Reiser (1997, p. 
16) reported more variable numbers on the same sites in 1995-1996, and 
based on these more recent observations, Dana (1997, pp. 3-5) suggested 
that populations could experience significant size fluctuations between 
years. At Hole-in-the-Mountain preserve, Minnesota, Dana (1991, pp. 36-
37) found peak abundance of approximately 1,000 Dakota skippers over 
about 40 ha (98 ac); he estimated that 2,000-3,000 individuals may have 
been alive at various times during the flight period and that only one-
third to one-half of adults were alive simultaneously. Where they 
occur, these high adult densities persist for only about a week to 10 
days during the single annual flight period (Selby and Glenn-Lewin 
1989, pp. 24-28).
    The percentage of sites surveyed each year in Minnesota with 
positive detections remained relatively stable from 1985 to 2005, with 
an average detection rate of 67 percent for all survey years with more 
than one site surveyed (excluding sites newly discovered in the first 
year it was discovered), an average of 70 percent detection rate for 
survey years with 5 or more sites surveyed and an average of 66 percent 
detection rate for survey years with 10 or more sites surveyed. One 
exception to the high detection rates was 1994; only 26 percent (5 of 
19 sites) of sites surveyed in 1994 resulted in positive detections. 
Recent surveys of the species resulted in significantly lower than 
average positive detections. The percent of sites surveyed each year 
with positive detections has recently decreased from 70 percent (7 of 
10 sites) in 2005, to 47 percent (8 of 17 sites) in 2007, to 56 percent 
(10 of 18 sites) in 2008, to 6 percent (1 of 18 sites) in 2012 (for 
years with greater than 10 sites surveyed, see Figure 1). Only one 
individual was detected in Minnesota during 2012 surveys, which 
included 18 sites with previous records and 23 prairie remnants without 
previous records for the species (Dana 2012c, pers. comm.; Runquist 
2012a, pers. comm.; Olsen 2012, pers. comm.). The cause for this sharp 
decline is unknown.

[[Page 63582]]

[GRAPHIC] [TIFF OMITTED] TP24OC13.088

    The Dakota skipper is presumed extirpated at 12 sites in Minnesota; 
at 7 of these sites the species has not been observed since 1984 or 
earlier. Four sites at which the species is now presumed to be 
extirpated have had fairly recent positive observations. The species 
was last observed at Prairie Waterfowl Production Area (WPA) in Big 
Stone County in 2000 (Skadsen 2000, p. 1), for example, but was not 
found in 2008 (Selby 2009a, p. i), 2010, and 2012 (Service 2013, 
unpubl. geodatabase). Dakota skippers were observed at the Glacial 
Lakes WPA in 2001 (Schlicht 2001b, p. 18), but the species was not 
observed in 2003, 2004, and 2005 (Selby 2006b, p. Appendix A xii); the 
species is now considered to be extirpated at that site (Service 2013, 
unpubl. geodatabase). The last observation of Dakota skipper at the Big 
Stone National Wildlife Refuge (NWR) in Lac Qui Parle County was in 
2000, and it was not observed during surveys in 2009, 2011, or 2012 
(Skadsen 2012a, p. 5). Dakota skippers were observed at Chippewa 
Prairie in 1995, but not in 1996, 2005, and 2012 (Service 2013, unpubl. 
geodatabase). Of the 18 sites where the species is possibly extirpated, 
10 have not been surveyed since the species was last seen in 1988 or 
earlier. Dakota skippers at two of the sites where the species is 
possibly extirpated have not been observed since 1991 (Service 2013, 
unpubl. geodatabase). The remaining 6 sites had positive observations 
prior to 1993, were surveyed once more recently, and had a negative 
observation (Service 2013, unpubl. geodatabase).
    The status of Dakota skipper is unknown at 22 sites; Dakota skipper 
have not been observed at 11 of these sites since the mid- to late 
1990s, despite one or two years of survey effort at several sites. The 
remaining 11 sites with unknown status have had positive observations 
in 2007 or more recently, but are given this designation due to a 
subsequent negative survey. For example, Dakota skipper was documented 
at the Gens Prairie in Murray County and Woodstock Prairie in Pipestone 
County in 2007, but the species was not observed during surveys in 2008 
(Selby 2009a, p. Appendix 5 li, xxxiii and Appendix 4 xlix).
    In 2007 and 2008, the Minnesota DNR carried out a broad survey 
effort to assess the status of Dakota skipper and other prairie 
butterflies in the State after experts noted significant declines in 
these species in west-central Minnesota beginning in 2003 (Selby 2006b, 
p. 30). Researchers surveyed 17 and 19 sites with previous Dakota 
skipper records in 2007 and 2008, respectively; Dakota skipper was 
found at 8 sites each year and at 1 site where it had not previously 
been recorded (Selby 2009a, p. 6). The surveys confirmed Dakota 
skipper's extirpation from one site in Cottonwood County, where it was 
last recorded in 1970.
    A parallel study in 2007 (Dana 2008), consisted of more intensive 
work at a few sites thought to contain some of the State's most viable 
populations of Dakota skipper. Among these sites was The Nature 
Conservancy's Hole-in-the-Mountain preserve in Lincoln County, which 
was the only Minnesota population rated as secure in 2002 (Cochrane and 
Delphey 2002, p. 16). The 2007 surveys indicated that the site still 
supported a substantial population, but that it may have decreased in 
size since earlier studies were conducted (Dana 1991, p. 36; Dana 2008, 
p. 18). Dakota skippers were not detected during the 2012 flight period 
(Runquist

[[Page 63583]]

2012, pp. 13-14, 18-20; Runquist 2012a, pers. comm.); therefore, we 
consider the status of the species at the Hole-in-the-Mountain preserve 
to be unknown.
    Relatively important populations of Dakota skipper in Minnesota may 
still occur at the Prairie Coteau, Felton Prairie, and Glacial Lakes 
complexes, but the 2012 survey results raised concern for the species' 
status at Prairie Coteau. The number of Dakota skippers encountered per 
100 m (328 ft) of transect at Prairie Coteau State Natural Area (SNA) 
were 1.7 in 1990 and 1.1 in 2007 (Dana 2008, p. 19). No Dakota skippers 
were observed at Prairie Coteau SNA during the 2012 flight period 
(Runquist 2012, pp. 9-10); therefore, we consider the status of the 
species to be unknown at that site. Selby (2009b, Appendix 4, p. iv) 
recorded 14 Dakota skippers during a 5-hour survey in 2007 at the 
Felton Prairie SNA. During a one-hour survey in 2008, nine Dakota 
skippers were recorded and with little indication of any substantial 
change since the previous year (Selby 2009b, Appendix 5, p. iv); Felton 
Prairie has not been resurveyed since 2008 (Service 2013, unpubl. 
geodatabase). The number of Dakota skippers recorded during recent 
surveys at Glacial Lakes State Park has been low despite good habitat 
conditions. An apparently widespread population was present as recently 
as 2001 when Skadsen (2001, p. 24) found Dakota skippers along almost 
all of 25 mi (40 km) of transect in and around the park--he recorded as 
many as 31 Dakota skippers along one transect (Skadsen 2001, p. 24). 
Selby (2009a, p. l and liv) surveyed the same areas in 2007 and 2008, 
describing habitat at survey sites as good to excellent, but recorded 
only eight Dakota skippers during about seven hours of surveys in and 
around the park (Selby 2009a, p. 1 and liv). Glacial Lakes State Park 
surveys conducted in 2012 were outside of the Dakota skipper flight 
period (Runquist 2012a, pers. comm.).
    In summary, the Dakota skipper is now considered to be extirpated 
or possibly extirpated from at least 30 of the 66 sites in Minnesota, 
which historically contained approximately 26 percent of all known 
historical Dakota skipper locations rangewide (Table 1). The species is 
considered to be present and unknown at 14 and 22 sites, respectively. 
However, only one individual male was detected in the State during 2012 
surveys, which included 18 sites with previous records; 2012 surveys 
for undiscovered populations were also carried out on 23 prairie 
remnants without previous records for the species. Similar surveys of 
prairie remnants with no previous documentation of Dakota skipper were 
completed in Minnesota in 2007 and 2008. Based on these surveys, the 
likelihood that significant undiscovered Dakota skipper populations 
occur in Minnesota is low.
North Dakota
    North Dakota historically contained approximately 21 percent of all 
known historical locations of Dakota skippers rangewide (Table 1); the 
State contained 54 historical sites distributed among 18 counties 
(Service 2013, unpubl. geodatabase). The Dakota skipper is currently 
present at 18 sites in 5 North Dakota counties, of these, 13 occur 
within the Towner-Karlsruhe complex in McHenry County, 1 is within the 
Sheyenne National Grasslands complex in Ransom County, 2 in northern 
McKenzie County, 1 site is in Wells County, and 1 site in McLean 
County. Of the 18 sites where we consider the Dakota skipper to be 
present, 15 sites had positive observations of the species in 2012 and 
the remaining 3 sites had positive observations between 1998 and 2003. 
The status of the species is unknown at 13 sites; 10 of these sites 
have not had positive records since the mid- to late 1990s and the 
other 3 sites had positive records between 2001 and 2003. The Dakota 
skipper is presumed extirpated from 13 sites and 4 counties, primarily 
due to heavy grazing, weed control, and other disturbances (e.g., 
bulldozing at Killdeer Mountain to reduce aspen growth, Royer 1997). 
The species is possibly extirpated from 10 additional sites and 3 
additional counties. Researcher surveyed 25 sites, believed to possibly 
have Dakota skipper populations, in 2012; of these sites, 23 had 
previous records of the species (Royer and Royer 2012a, entire). 
Thirteen of the 25 surveyed sites had Dakota skipper present (Royer and 
Royer 2012a, pp. 3-4; Royer and Royer 2012b, pp. 2-3). One new site was 
found in 2012 (Royer and Royer 2012a, p. 33), adjacent to a site with 
previous records but with different land-ownership, so the researcher 
considered it a new site. Another new site was found in North Dakota in 
2012, in Wells County, where two observations were made--possibly the 
same individual (HDR, Inc. 2012, pp. 21-23). At sites with Dakota 
skipper, lower average encounter frequencies were observed across the 
State in 2012 (state average = 9.4 encounters per hour) than during the 
1996-1997 statewide surveys (state average = 17.4 encounters per hour) 
(Royer and Royer 2012b, p. 5; Royer and Royer 2012a. pp. 7-8).
    Of the Dakota skipper populations in North Dakota, none may be 
secure, although the Towner-Karlsruhe complex was considered to be the 
stronghold for the species in the State in 2002 (Cochrane and Delphey 
2002, p. 17) and most of the sites where the species is currently 
present are still occupied by ``viable populations'' (Royer 2012a, 
pers. comm.). All of the habitat where the species is present in the 
Towner-Karlsruhe complex is Type A (wet-mesic) habitat (Royer and 
Marrone 1992a, p. 21-22; Royer et al. 2008, pp. 14-16). Five sites 
within the Towner-Karlsruhe complex are owned by the North Dakota State 
Land Department, and the remaining seven sites with extant populations 
are privately owned. Some Towner-Karlsruhe sites are linked by highway 
rights-of-way that contain native prairie vegetation and by other 
prairie remnants (Royer and Royer 2012a, p. 18). In 2002, none of these 
sites were described as secure (Cochrane and Delphey 2002, pp. 66-67) 
since each is subject to private or State management options that could 
extirpate Dakota skipper from the site. In 1999, it was estimated that 
about 30 percent of the Towner-Karlsruhe area still contained native 
prairie (Lenz 1999b, p. 2); more recent observations indicate that 
several native prairie sites have been invaded to varying extents by 
nonnative species, such as leafy spurge, Kentucky bluegrass, and 
alfalfa (Medicago sativa), and several are subject to intense grazing 
or early haying (Royer and Royer 2012b, pp. 5-6, 7-10, 13-16, 18-19, 
22-23; Royer 2012, in litt.).
    Dakota skipper populations in the Sheyenne National Grasslands 
complex have experienced intensive grazing, leafy spurge (Euphorbia 
esula) invasion, and the effects of herbicides used to control leafy 
spurge and grasshoppers (Royer 1997, pp. 15 and 27). For example, 
McCabe (1979, p. 36) cited the McLeod Prairie in the Sheyenne 
Grasslands in southeastern North Dakota as the best site for Dakota 
skippers in North Dakota. Since then, however, leafy spurge invasion 
has significantly modified the habitat and the Dakota skipper is now 
extirpated from the site (Royer 1997, p. 14). Swengel and Swengel 
(1999, p. 286) did not find Dakota skippers at eight survey sites in 
the Sheyenne grasslands during 1988-1997, although Royer did observe a 
few isolated Dakota skippers in the Sheyenne National Grasslands during 
this period (e.g., Royer 1997, pp. 14-15). Dakota skippers were 
recorded at one new site (Gregor) in the Sheyenne National Grasslands 
in 2001 (Spomer 2004, pp. 14-15). The status of Dakota skipper at the 
Gregor site is currently

[[Page 63584]]

unknown, since the species was not observed during the 2002 survey 
(Royer and Royer 2012a, pp. 3-4). Orwig (1996, p. 3) suggested that 
Brown's Ranch in Ransom County, owned by The Nature Conservancy, had 
potential to support a metapopulation (groups of local populations 
interconnected by dispersal habitat) in the Sheyenne River watershed. 
More recently, however, Spomer (2004, p. 36) found that the population 
there was not doing well, and Royer failed to find the species in 2012 
(Royer and Royer 2012a, p. 3). Therefore, the status of the species at 
the Brown Ranch site is unknown. Royer (1997, pp. 15 and 27) claimed 
that, throughout the Sheyenne Grasslands, both public and private lands 
have been so heavily grazed and altered by grasshopper and leafy spurge 
control that extirpation of Dakota skippers from the area is almost 
certain to occur. The population at Venlo Prairie, for example, 
deteriorated from good/fair in 2001 to poor in 2003 due to intense 
grazing and disappearance of flowers (Spomer 2004, pp. 9, 12); the 
species is now considered to be extirpated at that site.
    In 2002, experts ranked all sites outside of the two complexes 
discussed above as threatened or vulnerable; most were small and 
isolated populations threatened by conversion and invasive species 
(Cochrane and Delphey 2002, pp. 66-67). Most of these sites are now 
considered extirpated or possibly extirpated. Today, only 4 sites 
outside of the Towner-Karsruhe Complex and Sheyenne National Grasslands 
complexes are thought to have extant (present) Dakota skipper 
populations, including Garrison Training Center in McLean County. In 
addition to the Towner-Karsruhe Habitat Complex sites in McHenry 
County, only 2 of the 25 sites surveyed by Royer in 2012, both in 
northern McKenzie County, may have ``viable populations'' (Royer 2012b, 
pers. comm.), although only one individual was observed at each site in 
2012 (Royer and Royer 2012b, pp. 16-17).
    In summary, North Dakota contains approximately 21 percent (N= 53) 
of all known historical locations of the species rangewide; however, 
the current occupancy status of the Dakota skipper is unknown at 12 
sites, and it is considered to be extirpated or possibly extirpated 
from at least 23 of the 53 known sites in the state (Table 1). The 
species is considered to be present at only 18 sites in the State. 
North-central North Dakota may hold hope for the species' long-term 
conservation. Dakota skipper was detected at 13 of the 25 sites 
surveyed during 2012 (23 of the sites had previous Dakota skipper 
records); average encounter frequencies observed across the State in 
2012 (9.4 encounters per hour), however, were lower than during the 
1996-1997 statewide surveys (ND state average = 17.4 encounters per 
hour).
    Although only a small fraction of all grassland in North Dakota has 
been surveyed for Dakota skippers, a significant proportion of the un-
surveyed area is likely not suitable for Dakota skipper. The species 
was never detected at approximately 135 additional locations in North 
Dakota that were surveyed for the species from 1991-2012 (USFWS 2013, 
unpubl. geodatabase). Many of these sites have been surveyed multiple 
times over multiple years (USFWS 2013, unpubl. geodatabase). Surveys 
for the Dakota skipper are typically conducted only in areas where 
floristic characteristics are indicative of their presence. New 
potential sites surveyed are generally focused on prairie habitat that 
appear suitable for the species and have a good potential of finding 
the species, in other words, sites are not randomly selected across the 
landscape. Therefore, these sites have a higher likelihood of detecting 
the species than at sites randomly selected across the landscape. Based 
on these surveys, the likelihood that significant numbers of 
undiscovered Dakota skipper populations occur in North Dakota is low. 
Moreover, data available from the numerous sites that have been 
surveyed are likely to be representative of areas that have not been 
surveyed--that is, population trends and the nature and extent of 
stressors that may impact the populations in un-surveyed areas can 
reasonably be inferred by analyzing data collected from the sites that 
have been surveyed.
South Dakota
    South Dakota historically contained approximately 33 percent of all 
known locations of Dakota skippers rangewide (Table 1). Since the 
earliest known record of Dakota skipper (1905) of the species in South 
Dakota, 85 sites have been documented across 11 counties in the State, 
but recent surveys indicate that the species is declining in the State 
(Service 2013, unpubl. geodatabase). Of the 85 historical sites, Dakota 
skipper is presumed extirpated from 15 sites and 2 counties (Brown and 
Moody), and is possibly extirpated from 10 additional sites. Dakota 
skipper is considered present at 14 sites and the status of the species 
is unknown at 46 sites. Twenty-six sites in South Dakota with previous 
Dakota skipper records were surveyed in 2012; the species was detected 
at 9 of those sites (Service 2013, unpubl. geodatabase). Eight 
additional sites within the species' historical range were surveyed 
during the 2012 flight period, which resulted in the discovery of two 
new nearby Dakota skipper sites (Service 2013, unpubl. geodatabase; 
Skadsen 2012a, pers. comm.). The proportion of positive surveys at 
known sites has fluctuated over time; however, the 2012 surveys had the 
lowest positive detection rate (35 percent) for the last 16 years 
(since 1996), much less than comparable survey years (years with 10 or 
more sites surveyed) in South Dakota.
    While there are some sites with earlier records, most South Dakota 
sites were initially documented during extensive surveys conducted 
during 1996 to 1998. Forty-eight locations without previous records 
were surveyed during 2002-2004, which resulted in the discovery of 20 
new Dakota skipper sites in northeastern South Dakota (Skadsen 2003, p. 
8; Skadsen 2004, pp. 3-6), but due to more recent negative surveys, the 
occupancy of the species is currently unknown or extirpated at many of 
these sites (Skadsen 2011, p. 5; Skadsen 2012, pp. 4-5; Skadsen, 2012, 
pers. comm.; Skadsen 2003, p. 10; Skadsen 2004, p. 2;; Skadsen 2006a, 
p. 2, 10; Skadsen 2006b, p. 5; Skadsen 2007, p. 3; Skadsen 2008, p. 3, 
12; Skadsen 2009, p. 3). Additional survey effort resulted in the 
discovery of nine new sites between 2005 and 2012, with a maximum of 
three new sites discovered in 2006 (Skadsen 2010a, p. 6; Skadsen 2012, 
pp. 4-5; Skadsen 2012, pers. comm.; Skadsen 2005, pp. 5-6, Skadsen 
2006a, p. 12; Skadsen 2006b, p. 5; Skadsen 2007, p. 3; Skadsen 2008, p. 
9; Skadsen 2009, p. 2). Eight additional sites without previous 
documentation of the species were surveyed in 2012, which resulted in 
the discovery of two nearby sites (Service 2013, unpubl. geodatabase). 
To summarize, new sites have been discovered in South Dakota during 
most survey years since 2002, however, the number of new sites 
discovered each year has been low recently; 2 or 3 new sites have been 
discovered each survey year since 2005 (3 sites in 2005, 2 sites in 
2006, 2 sites in 2007, zero sites in 2010, and 2 sites in 2012). The 
rate that known sites are becoming extirpated is higher than the rate 
of new discovery--the occupancy of the species at many sites is now 
unknown or extirpated due to more recent negative surveys.
    The species has never been documented in Clark County, but because 
few surveys have been conducted there, the county may contain 
undiscovered populations (Skadsen 2006b, p. 1). Skadsen (2012b,

[[Page 63585]]

pers. comm.) doubts the existence of public lands with suitable Dakota 
skipper habitat in Clark County and has not received permission to 
survey a few possible suitable locations that are privately owned.
    Although only a small fraction of all grassland in eastern South 
Dakota has been surveyed for Dakota skippers (e.g., Dakota skipper 
surveys have been conducted on less than approximately 30,000 acres 
(12,140 ha) in South Dakota within the species range (Service 2013, 
unpubl. geodatabase)), a significant proportion of the un-surveyed area 
is likely not suitable for the Dakota skipper. For example, there is an 
estimated 1,620,549 acres (ac) (655,813 hectares (ha)) of unbroken 
(untilled) grasslands (excluding Conservation Reserve Program (CRP) 
grasslands, which generally do not provide habitat for the Dakota 
skipper (Larson 2013, pers. comm.)) in the 9 counties where the Dakota 
skipper is considered be present or to have unknown occupancy in South 
Dakota (HAPET 2012, unpubl. data). Additional areas of unbroken prairie 
were estimated in three other counties where the species may have 
occurred historically (HAPET 2012, unpubl. data). While these lands 
represent unbroken grassland in South Dakota, the models used to 
identify unbroken grassland are not able to identify plant species, 
plant species composition, floristic quality, or presence of invasive 
species (Loesch 2013 pers. comm.). Therefore, these unbroken grasslands 
may not contain the specific native prairie plants that the Dakota 
skipper requires (as discussed in detail in the Background section of 
this proposed rule) and, therefore, may not equate to suitable habitat 
for the species.
    The species was never detected at approximately 73 additional 
locations in South Dakota that were surveyed from 1991 through 2012 
(USFWS 2013, unpubl. geodatabase). Several of these sites have been 
surveyed multiple times in one year or during multiple years (USFWS 
2013, unpubl. geodatabase). Surveys for Dakota skipper are typically 
conducted only in areas where floristic characteristics are indicative 
of their presence. For example, in South Dakota, Skadsen (1997, p. 2) 
selected for surveys dry-mesic prairie that supported purple coneflower 
and wet-mesic prairie that supported wood lily and mountain deathcamas 
based on searches for these sites by car and reports from resource 
managers. New potential sites surveyed are generally focused on prairie 
habitat that appear suitable for the species and have a good potential 
of finding the species, in other words, sites are not randomly selected 
across the landscape. Therefore, these sites have a higher likelihood 
of detecting the species than at sites randomly selected across the 
landscape. Based on these surveys, the likelihood that significant 
undiscovered Dakota skipper populations occur in South Dakota is low. 
Moreover, data available from the numerous sites that have been 
surveyed are likely to be representative of areas that have not been 
surveyed--that is, population trends and the nature and extent of 
stressors that may impact the populations in un-surveyed areas can 
reasonably be inferred by analyzing data collected from the sites that 
have been surveyed.
    Since there is little long-term quantitative data for sites in 
South Dakota, we examined presence-absence (non-detection) data over 
time. The percent of sites surveyed each year with positive detections 
of the species remained relatively stable from 1985 to 2010, with an 
average positive detection rate of 63 percent for all survey years with 
more than one site surveyed (excluding new sites for the first year of 
discovery), an average positive detection rate of 60 percent for survey 
years with at least 5 sites surveyed, and an average positive detection 
rate of 71 percent for survey years with at least 10 sites surveyed. 
One exception to the high detection rates was during the 1991 survey 
year when none (0 of 7 sites) of the sites surveyed in 1991 resulted in 
positive detections of the species, excluding 3 new sites that were 
discovered that year. Another exception was in 1996, when 2 of the 8 
sites with previous records surveyed had a positive detection; however, 
6 new sites were discovered that year. The detection rate remained 
relatively stable until 2010, when the percent of sites with positive 
detections fell from 89 percent (8 of 9 sites) in 2010, to 46 percent 
(5 of 11 sites) in 2011, and 35 percent (9 of 26 sites) in 2012 (Figure 
2). These types of fluctuations had been observed in prior years; 
therefore, it is difficult to determine a clear trend in the data using 
positive detections--the last two survey years may fall within the 
normal range of variation.

[[Page 63586]]

[GRAPHIC] [TIFF OMITTED] TP24OC13.089

    The Outer Coteau des Prairies sub-section of the North Central 
Glaciated Plains section of Bailey's Eco-regions is thought to be a 
stronghold for Dakota skipper, since nearly 40 percent of the total 
documented Dakota skipper sites are within that subsection (83 of the 
259 documented sites--Service 2013, unpubl. geodatabase). Most of these 
Outer Coteau des Prairie sites are in South Dakota; 73 of the 85 Dakota 
skipper sites in South Dakota are within the Outer Coteau des Prairies 
subsection (Service 2013, unpubl. geodatabase). Dakota skipper is 
considered to be present at only 10 of those 73 sites--the species 
status is unknown at 41 of those sites, possibly extirpated at 8 sites, 
and extirpated at the remaining 13 sites within that ecoregion 
subsection in South Dakota (Service 2013, unpubl. geodatabase).
    In summary, South Dakota historically contained approximately 33 
percent of all known locations of the species rangewide. The current 
occupancy status of the Dakota skipper is unknown at 46 sites and it is 
considered to be extirpated or possibly extirpated from at least 25 of 
the 85 known sites in the State, although large areas of grasslands 
remain in South Dakota and substantial additional populations of Dakota 
skipper would be expected to be found if more surveys were conducted. 
Furthermore, downward trends and threats impacting populations at known 
sites are also likely occurring at potentially undiscovered sites. The 
species is considered to be present at 14 of the 85 documented sites in 
the State. Twenty-six sites in South Dakota with previous Dakota 
skipper records were surveyed in 2012; the species was detected at nine 
of those sites; eight sites with no previous records for the species 
were surveyed during the 2012 flight period, which resulted in the 
discovery of two nearby sites. The proportion of positive surveys at 
known sites has fluctuated over time; however, the 2012 surveys had the 
lowest positive detection rate (35 percent) for the last 16 years 
(since 1996)--much less than comparable survey years in South Dakota.
Manitoba
    Manitoba historically contained approximately 14 percent (N = 36) 
of the known locations of the Dakota skipper rangewide. The Dakota 
skipper is considered present at 1 isolated site and 30 sites split 
between 2 distinct complexes, 14 sites near Griswold and 16 sites along 
Lake Manitoba. The 14 sites near Griswold are located approximately 200 
km (124 mi) southwest of the populations along Lake Manitoba (at 16 
sites) and about 125 km (78 mi) northeast of the nearest population in 
Saskatchewan (Webster 2003, pp. 5-6; Webster 2007, p. 4). The species 
is presumed extirpated or possibly extirpated from five sites in 
Manitoba, including from the Tallgrass Prairie Preserve, where it has 
not been found in the seven most recent survey years (Webster 2003, p. 
5; Westwood et al. 2012, p. 1; Westwood 2007, pers. comm.; Hamel et al. 
2013, pp. 8-16)--(the later surveys were focused on Poweshiek 
skipperlings, but other species were recorded) and one site that was 
converted to a flaxseed field (Webster 2003, p. 7). Population

[[Page 63587]]

estimates and trends at these sites have not been examined 
quantitatively; however, the population appears to be stable at two 
sites with repeated survey years. Numbers observed during searches at a 
site near Griswold in 2007 did not appear to change appreciably since 
2002 surveys, when the population was estimated (non-quantitatively) to 
be approximately 750 individuals (Webster 2003, p. 5; Webster 2007, p. 
4). A total of 273 adults were observed during a 3.3-hour survey at the 
second site, where the population was estimated non-quantitatively to 
be about 2,000 individuals (Webster 2007, p. 4).
    Dakota skipper was first recorded near Miniota in 1944 and then at 
two additional sites in the early 1990s. In 2002, the species was 
observed at 19 sites near Lundar, within about 25 km (16 mi) east of 
Lake Manitoba (Webster 2003, p. 4); however, most of these sites have 
not been surveyed since. In 2007, researchers surveyed 16 sites for the 
Dakota skipper near Griswold, Manitoba (Webster 2007, p. 4) and found 
Dakota skippers at 14 of the 16 sites; 12 of these represent new sites 
for the species in Manitoba (Webster 2007, p. 4). Several additional 
areas were examined for potential Dakota skipper habitat in 2007, 
including areas east of Hwy 21, within the Lauder Sandhills Wildlife 
Management Area, north of Oak Lake and near Tilston, Sinclair, Cromer, 
and Brandon, as well as other locations. Most of the areas examined 
were under row crop agriculture, were heavily grazed, were dry scrub 
prairies or were otherwise habitats unsuitable for Dakota skipper 
(Webster 2007, p. 6). The areas near Brandon and the high ground within 
the wetland complexes near Oak Lake may still contain suitable habitat 
(Webster 2007, p. 6).
    The nearest known extant (present) population of Dakota skippers in 
Manitoba is approximately 120 km (75 mi) from the closest extant 
(present) population in North Dakota and about 200 km (125 mi) from the 
closest Saskatchewan population. Britten and Glasford (2002, pp. 367, 
372) suggested that Manitoba populations are genetically distinct from 
a group of populations in Minnesota and South Dakota, although 
populations in additional intervening locations should be sampled to 
confirm this hypothesis (Runquist 2012b, pers. comm.).
Saskatchewan
    Saskatchewan historically contained approximately 5 percent (N= 14) 
of all known records of Dakota skippers rangewide. In Saskatchewan, the 
Dakota skipper is restricted to undisturbed or lightly grazed, steep, 
south-facing hills near the Souris River (Webster 2007, p. ii). The 
Dakota skipper was first recorded south of Oxbow, Saskatchewan, in 2001 
where three males were collected (Hooper 2003, p. 124) on an ungrazed 
knoll within a patch of mixed-grass prairie that was approximately one 
ha (2 ac) in extent. Dakota skippers were found at three additional 
sites during 2002 surveys (Webster 2003, pp. 6-7). In 2007, researchers 
surveyed 16 sites in southeastern Saskatchewan and found Dakota 
skippers at 10 of these sites (including Oxbow); 8 of these represent 
new sites for the species in Saskatchewan (Webster 2007, p. i). During 
2007 surveys, which were conducted late in the flight period, only a 
few individuals were observed at each site where the species was 
present (Webster 2007, p. ii). Nine of these sites where the species 
was found in 2007 were surveyed along an approximate 50-km (31-mi) 
stretch of steep hillsides along the ridgeline north of Souris River; 
distances between sites range from 1 to 28 km (0.8 mi to 17 mi). We 
consider Dakota skipper to be present at all 14 sites in Saskatchewan, 
although 3 of those sites have not been surveyed since 2002. The 
nearest known extant population of Dakota skippers in Saskatchewan is 
approximately 111 km (69 mi) from the closest extant (present) 
population in North Dakota and 200 km (125 mi) from the closest 
Manitoba population.
Poweshiek skipperling
Species Description
    The Poweshiek skipperling (Oarisma poweshiek) is a member of the 
skipper family, Hesperiidae, and was first described by Parker (1870, 
pp. 271-272). Parker (1870, pp. 271-272) provided the original 
description of this species from his type series collected near 
Grinnell, Iowa. It was named for the county in which it was found 
(Poweshiek County), but it was misspelled, Powesheik, in the original 
description. This spelling was retained by most early authorities 
(Lindsey 1922, p. 61; Holland 1931, p. 360). Miller and Brown (1981, p. 
31) used the corrected spelling, Poweshiek, but then Miller and Ferris 
(1989, p. 31) changed it back in their supplement. Current usage is 
mixed, with many authorities retaining the original spelling (e.g., 
Miller 1992, p. 20), while others have opted for the corrected spelling 
(Layberry et al. 1998, p. 48; Opler et al. 1998, p. 363; Glassberg 
1999, p. 167; Brock and Kaufman 2003, p. 306). Layberry et al. (1998, 
p. 48) state ``. . . since it is a clear case of an original incorrect 
spelling it can be corrected [rule 32(c)ii of the International Code of 
Zoological Nomenclature].''
    Poweshiek skipperlings are small and slender-bodied, with a 
wingspan generally ranging from 2.3 to 3.0 cm (0.9 to 1.2 in). The size 
of Poweshiek skipperlings appears to vary somewhat across their range 
(Royer and Marrone 1992b, p. 3). North Dakota and South Dakota 
specimens tend to be slightly smaller than the 2.9 to 3.2 cm (1.1 to 
1.3 in) range given by Parker (1870) for the type specimens from 
Grinnell, Iowa (Royer and Marrone 1992b, p. 3). A sample of Richland 
County, North Dakota, specimens from Royer's collection had an average 
wingspan of 2.8 cm (1.1 in) for males and 3.0 cm (1.2 in) for females. 
South Dakota specimens in Marrone's collection had an average wingspan 
of 2.6 cm (1.0 in) for males and 2.7 cm (1.1 in) for females. The upper 
wing surface is dark brown with a band of orange along the leading edge 
of the forewing. Ground color of the lower surface is also dark brown, 
but the veins of all but the anal third of the hindwing are outlined in 
hoary white, giving an overall white appearance to the undersurface.
    The Poweshiek skipperling is most easily confused with the Garita 
skipperling (Oarisma garita), which can be distinguished from Poweshiek 
skipperling by their smaller size, quicker flight, and overall golden-
bronze color (Royer and Marrone 1992b, p. 3). Another distinguishing 
feature is the color of the anal area of the ventral hindwing (orange 
in Garita; dark brown in Poweshiek). The Garita skipperling generally 
occurs west of Poweshiek skipperling range, although there are records 
of both species from two counties in southeastern North Dakota and two 
counties in northwestern Minnesota (Montana State University--Big Sky 
Institute 2012, Butterflies of North America http://www.butterfliesandmoths.org/ Accessed 5/14/12; Minnesota Department of 
Natural Resources (DNR) 2012, Rare features database. Accessed 5/14/
12).
    McAlpine (1972, pp. 85-92) described Poweshiek skipperling eggs as 
pale yellowish green, mushroom shaped with a flattened bottom, a 
slightly depressed micropyle (pore in the egg's membrane through which 
the sperm enter) and smooth surfaced. They were 0.8 millimeters (mm) 
(0.01 in) long, 0.7 mm (0.03 in) wide and 0.5 mm (0.02 in) high. The 
overall color of the head and body of the larvae is pale grass green, 
with a distinctive darker green mid-dorsal stripe and seven cream-
colored stripes on each side. First instars were 1.8 mm (0.07 in) at 
hatching, and the

[[Page 63588]]

lone 7th instar survivor was 23.6 mm (1.0 in) near the end of that 
stage. McAlpine did not have any observations past the 7th instar (the 
stage between successive molts, the first instar being between hatching 
and the first molt) (McAlpine 1972, pp. 85-93).
General Life History
    Poweshiek skipperlings lay their eggs near the tips of leaf blades 
and overwinter as larvae on the host plants (Bureau of Endangered 
Resources in Swengel and Swengel 1999, p. 285, Borkin 2000a, p. 7). 
McAlpine (1972, pp. 85-92) described the various life-history stages of 
Poweshiek skipperling. McAlpine (1972, pp. 85-93) observed hatching of 
larvae Poweshiek skipperling after about nine days. McAlpine's records 
were incomplete, and he did not have any observations past the 7th 
instar, but he believed that there should have been one or two 
additional instars, followed by the chrysalis (pupa) and then the imago 
(adult) stages (McAlpine 1972, pp. 85-93). After hatching, Poweshiek 
skipperling larvae crawl to the base of grasses, but unlike Dakota 
skippers, Poweshiek skipperling do not form shelters underground 
(McAlpine 1972, pp. 88-92; Borkin 1995a, p. 9; Borkin 2008, pers. 
comm.). Poweshiek skipperling are not known to form shelters, instead 
the larvae overwinter up on the blades of grasses and on the stem near 
the base of the plant (Borkin 2008, pers. comm.; Dana 2008, pers. 
comm.). Borkin (2008, pers. comm.) observed larvae moving to the tips 
of grass blades to feed on the outer and thinner edges of the blades, 
with later movement down and among blades.
Food and Water
    For the Poweshiek skipperling, preferred nectar plants vary across 
its geographic range. Smooth ox-eye (Heliopsis helianthoides) and 
purple coneflower were noted as the favored nectar plants in Iowa, 
Minnesota, and North Dakota (Swengel and Swengel 1999, p. 280). Other 
nectar species used, in descending order of number of observations, 
were stiff tickseed (Coreopsis palmata), black-eyed Susan, and 
palespike lobelia (Lobelia spicata) (Swengel and Swengel 1999, p. 280). 
On drier prairie habitats in Iowa and Minnesota, purple coneflower is 
used almost exclusively, and the emergence of the adults corresponds 
closely to the early maturity of this species' disk florets (Selby 
2005, p. 5). On the wetter prairie habitats of Canada and the fen 
habitats of Michigan, favored nectar plants are black-eyed Susan, 
palespike lobelia, sticky tofieldia (Triantha glutinosa), and shrubby 
cinquefoil (Dasiphora fruticosa ssp. floribunda) (Nielsen 1970, p. 46; 
Holzman 1972, p. 111; Catling and Lafontaine 1986, p. 65; Bess 1988, p. 
13; Summerville and Clampitt 1999, p. 231). In addition to nutrition, 
the nectar of flowering forbs provides water for Poweshiek skipperling, 
which is necessary to avoid desiccation during flight activity (Dana 
2013, pers. comm.).
    Until recently, the larval food plant was presumed to be elliptic 
spikerush (Eleocharis elliptica) or sedges, but this was based on 
limited observations, primarily from the Michigan populations (e.g, 
Holzman 1972, p. 113). More recent observations show that the preferred 
larval food plant for some populations of Poweshiek skipperling is 
prairie dropseed (Sporobolus heterolepis) (Borkin 1995b, p. 6); larvae 
have also been observed feeding on little bluestem (Schizachyrium 
scoparium) (Borkin 1995b, pp. 5-6) and sideoats grama (Bouteloua 
curtipendula) (Dana 2005a, pers. comm.). Poweshiek skipperling have 
been observed laying eggs (ovipositing) on mat muhly (Muhlenbergia 
richardsonis) (Cuthrell 2012a, pers. comm.), a grass in Michigan's 
prairie fens (Penskar and Higman 1999, p. 1).
    In southwestern Minnesota dry hill prairies, Poweshiek skipperling 
oviposition was observed on prairie dropseed, little bluestem, big 
bluestem (Andropogon gerardii), porcupine grass (Hesperostipa spartea), 
and a couple unidentified species; a larva was observed feeding on 
sideoats grama (Dana 2005a, pers. comm.). Poweshiek skipperlings were 
observed to oviposit on big bluestem in Wisconsin (Borkin 2012a, pers. 
comm.), although indiscriminate oviposition on unsuitable larval plants 
has been observed during high summer temperatures (Borkin 1995a, p. 6). 
Dana (2005b, pers. comm.) noted that larvae and ovipositing females 
prefer grasses with ``very fine, threadlike structures'' and 
hypothesized that Poweshiek skipperling lack a specific host and may 
adapt to acceptable plant species at a site.
Dispersal
    Poweshiek skipperlings are also not known to disperse widely; the 
species was evaluated among 291 butterfly species in Canada as having 
relatively low mobility; experts estimated Poweshiek skipperling to 
have a mean mobility of 2 (standard deviation = 1.4) on a scale of 0 
(sedentary) to 10 (highly mobile) (Burke et al. 2011, p. 2279; 
Fitzsimmons 2012, pers. comm.). A maximum dispersal distance of 1.6 km 
(1.0 mi) is estimated to be a reasonable and likely distance for male 
Poweshiek skipperling to travel between patches of prairie habitat 
separated by structurally similar habitats (e.g., perennial grasslands 
but not necessarily native prairie). The species, however, will not 
likely disperse across habitat that is not structurally similar to 
native prairies, such as certain types of row crops or anywhere not 
dominated by grasses (Westwood 2012a and 2012b, pers. comm; Dana 2012b, 
pers. comm.). In Manitoba, Poweshiek skipperling have been observed 
avoiding dispersal over short distances, even to suitable habitat, if a 
barrier such as a road exists between suitable prairie habitat or 
nectar sources (Westwood et al. 2012, p.18). Since experts estimated 
Dakota skippers to have a mean mobility of 3.5 (standard deviation = 
0.7) on a scale of 0 (sedentary) to 10 (highly mobile), which is higher 
than the estimate for Poweshiek skipperling (mean mobility of 2) (Burke 
et al. 2011, p. 2279; Fitzsimmons 2012, pers. comm.), a more 
conservative estimated dispersal distance would be that of the Dakota 
skipper, approximately 1 km (0.6 mi) (Cochrane and Delphey 2002, p. 6).
    In summary, dispersal of Poweshiek skipperling is very limited due 
in part to its short adult life span and single annual flight. 
Therefore, the species' extirpation from a site is likely permanent 
unless it is within about 1 km (0.6 mi) of a site that generates a 
sufficient number of emigrants or is artificially reintroduced to a 
site; however, the capability to propagate the Poweshiek skipperling is 
currently lacking.
Habitat
    Poweshiek skipperling habitats include prairie fens, grassy lake 
and stream margins, moist meadows, and wet-mesic to dry tallgrass 
prairie. McCabe and Post (McCabe and Post 1977a, p. 38) describe the 
species' habitat in North Dakota as ``. . . high dry prairie and low, 
moist prairie stretches as well as old fields and meadows.'' Royer and 
Marrone (1992b, p. 12) describe Poweshiek skipperling habitat in North 
Dakota and South Dakota as moist ground in undisturbed native tallgrass 
prairies. Poweshiek skipperling habitat throughout Iowa and Minnesota 
is described as both ``high dry'' and ``low wet'' prairie (McCabe and 
Post 1977a, p. 38). The only documented Illinois record was associated 
with high rolling prairie (Dodge 1872, p. 218); the only documented 
Indiana record was from marshy lakeshores and wetlands

[[Page 63589]]

(Blatchley 1891, p. 398; Shull 1987, p. 29).
    Southern dry prairies in Minnesota are described as having sparse 
shrub cover (less than 5 percent) composed primarily of leadplant, with 
prairie rose, wormwood sage, or smooth sumac present and few, if any, 
trees (Minnesota DNR 2012a, p. 1). Southern mesic prairies also have 
sparse shrubs (5-25 percent cover) consisting of leadplant and prairie 
rose with occasional wolfberry (Symphoricarpos occidentalis) and few, 
if any, trees (Minnesota DNR 2012b, p. 1).
    The disjunct populations of Poweshiek skipperlings in Michigan have 
more narrowly defined habitat preferences, variously described as wet 
marshy meadows (Holzman 1972, p. 114), bog fen meadows or carrs (Shuey 
1985, p. 181), sedge fens (Bess 1988, p. 13), and prairie fens 
(Michigan Natural Features Inventory 2011, unpubl. data; Michigan 
Natural Features Inventory 2012, unpubl. data); prairie fen is the 
currently accepted name for this habitat type. Bess (1988, p. 13) found 
the species primarily in the drier portions of Liberty Fen, Jackson 
County, dominated by ``low sedges'' and an abundance of nectar sources. 
Summerville and Clampitt (1999, p. 231) noted that the population was 
concentrated in areas dominated by spikerush and that only 10-15 
percent of the fen area was occupied despite the abundance of nectar 
sources throughout. Poweshiek skipperling have been described as 
occupying peat domes within larger prairie fen complexes in areas 
either dominated by mat muhly or prairie dropseed (Cuthrell 2013a, 
pers. comm.). A few prairie fens in Michigan also contain other rare 
butterflies, such as Mitchell's satyr and swamp metalmark (Cuthrell 
2013a, pers. comm.).
    Poweshiek skipperling populations in Wisconsin are also disjunct 
from the population to the west and are associated with areas that 
contain intermixed wet-mesic, and dry-mesic prairie habitats (Borkin 
1995b, p. 6). The dry-mesic habitats contain ``extensive patches of 
prairie dropseed and little bluestem grasses'' (Borkin 1995b, p. 7). 
Survival in wetter areas, which tend to burn cooler and less 
completely, coupled with low recolonization rates, or the 
disproportionate loss of wet versus dry prairie could give the false 
impression that the wet areas were their preferred habitat (Borkin 
1995b, p. 7). Like Dakota skipper, Poweshiek skipperling larvae may be 
vulnerable to desiccation during dry summer months (Borkin 2012a, pers. 
comm.) and require movement of shallow groundwater to the soil surface 
or wet low areas to provide relief from high summer temperatures or dry 
conditions (Royer et al. 2008, pp. 2, 16; Borkin 2012a, pers. comm.). 
Humidity may also be an essential factor to larval survival during 
winter months since the larvae cannot take in water during that time 
and depend on humid air to minimize water loss through respiration 
(Dana 2013, pers. comm.). Royer (2008, pp. 14-15) measured 
microclimalogical (climate in a small space, such as at or near the 
soil surface) levels within ``larval nesting zones'' (between the soil 
surface and 2 cm deep) at six known Poweshiek skipperling sites, and 
found an acceptable rangewide seasonal (summer) mean temperature range 
of 18 to 21 [deg]C (64 to 70[emsp14][deg]F), rangewide seasonal mean 
dew point ranging from 14 to 17 [deg]C (57 to 63[emsp14][deg]F), and 
rangewide seasonal mean relative humidity between 73 and 85 percent
    Canadian populations of Poweshiek skipperlings are restricted to a 
single 2,300-ha (5,683-ac) area in southeastern Manitoba (COSEWIC 2003, 
p. 5). The wet to mesic tallgrass prairie in this area is characterized 
by low relief (1-2 m (3-7 ft)), with alternating lower, wetter areas 
and higher, drier prairie; Poweshiek skipperlings tend to be 
concentrated on or near the edge of the higher, drier prairie (COSEWIC 
2003, p. 8). Spikerush is frequent in the wetter areas, and prairie 
dropseed, black-eyed Susan, and palespike lobelia are frequent in the 
drier areas (COSEWIC 2003, pp. 7-8).
    Prairie fen habitat soils in Michigan are described as saturated 
organic soils (sedge peat and wood peat) and marl, a calcium carbonate 
(CaCO3) precipitate (MINFI Web site accessed August 3, 
2012). In other states, soil textures in Poweshiek skipperling habitats 
are classified as loam, sandy loam, or loamy sand (Royer et al. 2008, 
pp. 3, 10); soils in moraine deposits are described as gravelly, except 
the deposits associated with glacial lakes.
Population Distribution and Occupancy
    The Poweshiek skipperling is historically known from eight states, 
ranging widely over the native wet-mesic to dry tallgrass prairies from 
eastern North and South Dakota (Royer and Marrone 1992b, pp. 4-5) 
through Iowa (Nekola and Schlicht 2007, p. 7) and Minnesota (Minnesota 
DNR, Division of Ecological Resources, unpubl. data), with occurrences 
also documented in northern Illinois (Dodge 1872, p. 218), Indiana 
(Blatchley 1891, p. 898), Michigan (Holzman 1972, p. 111; McAlpine 
1972, p. 83), and Wisconsin (Borkin 2011, in litt.; Selby 2010, p. 22). 
The relatively recent discovery of Poweshiek skipperling populations in 
the Canadian province of Manitoba further extends its known historical 
northern distribution (Westwood 2010, pp. 7-22; Dupont 2010, pers. 
comm.). Additional historical accounts of Poweshiek skipperling from 
the States of Montana, Colorado, and Nebraska are likely 
misidentifications of its western congener, the Garita skipperling.
    Once common and abundant throughout native prairies in eight states 
and at least one Canadian province, the Poweshiek skipperling and its 
habitat have experienced significant declines. The species is 
considered to be present at a few native prairie remnants in two states 
and one location in Manitoba, Canada. The species is presumed 
extirpated from Illinois and Indiana, and the status of the species is 
uncertain in four of the six states with relatively recent records 
(within the last 20 years). The historical distribution of Poweshiek 
skipperling may never be precisely known because ``much of tallgrass 
prairie was extirpated prior to extensive ecological study'' (Steinauer 
and Collins 1994, p. 42), such as butterfly surveys. Destruction of 
tallgrass and mixed-grass prairie began in 1830 (Sampson and Knopf 
1994, p. 418), but significant documentation of the ecosystem's 
butterfly fauna did not begin until about 1960. Therefore, most of the 
decline of the Poweshiek skipperling probably went unrecorded. 
Poweshiek skipperling dispersal is very limited due in part to its 
short adult life span and single annual flight. Therefore, the species' 
extirpation from a site is likely permanent unless it is within about 1 
km (0.6 mi) of a site that generates a sufficient number of emigrants 
or is artificially reintroduced to a site.
    Recent survey data indicate that Poweshiek skipperling has declined 
to zero or to undetectable levels at 87 percent of sites where it has 
ever been recorded. Until about 2003, Poweshiek skipperling was 
regarded as the most frequently and reliably encountered prairie-
obligate skipper butterfly in Minnesota, which contains nearly 50 
percent of all known Poweshiek skipperling locations rangewide. Numbers 
and distribution dropped dramatically in subsequent years, however, and 
the species has not been seen in Minnesota since 2007. In Iowa, the 
Poweshiek skipperling was found at 2 of 33 sites with previous records 
surveyed in 2007; the species was last observed at one site in 2008. 
Iowa contains about 14 percent of documented sites rangewide. 
Unidentified threats to the species have acted to extirpate or sharply 
diminish

[[Page 63590]]

populations at all or the vast majority of sites in Iowa and Minnesota 
(Dana 2008, p. 16; Selby 2010, p. 7).
    South Dakota historically contained about 24 percent of the 
rangewide sites with documented presence of Poweshiek skipperling, 
although recent surveys in that State also suggest an emergent and 
mysterious decline. The species was last observed in South Dakota in 
2008, at three sites. North Dakota historically contained about six 
percent of the rangewide sites with documented presence of Poweshiek 
skipperling; the species was last observed in North Dakota in 2001. 
Survey efforts in North Dakota have been minimal between 1998 and 2011, 
but surveys conducted in 1997 documented more than 10 Poweshiek 
skipperlings at 1 site; 6 individuals were counted at 1 site, and 0 
were detected at 6 other sites. Surveys conducted during the 2012 
flight season resulted in zero detections of the species.
    Seven Michigan sites were recently ranked as having good or better 
``viability'', a habitat-based element occurrence rank assigned by the 
Michigan Natural Features Inventory (2011); however, the number of 
individuals observed at a few of those sites has declined in recent 
years and the species is presumed extirpated from one of those sites. 
Currently, four of the ten extant occurrences of Poweshiek skipperling 
in Michigan are considered to have good or better viability (Michigan 
Natural Features Inventory (2011, unpubl. data). Each of those faces 
threats of at least low to moderate magnitude, and the State contains 
only about 6 percent of all known historical Poweshiek skipperling 
records. There is one population of Poweshiek skipperling in Wisconsin 
with fairly consistent numbers observed over the last 5 years (17 to 63 
individuals counted, no consistent measure of effort) and one 
population in Manitoba with fairly consistent numbers (typically 
hundreds of individuals observed each year). To summarize, of the 296 
documented sites, there are 14 sites where we consider the Poweshiek 
skipperling to be present, 131 sites with unknown status, 98 possibly 
extirpated sites, and 53 where we consider the species to be extirpated 
(Table 2). The distribution and status of Poweshiek skipperling in each 
state of known historical or extant occurrence are described in detail 
below.

Table 2--Number of Historically Documented Poweshiek Skipperling Sites Within Each State and the Number of Sites
             Where the Species Is Thought To Be Present, Unknown, Possibly Extirpated, or Extirpated
----------------------------------------------------------------------------------------------------------------
                                                                                                      Percent of
                                                                                                      the total
                                                           Possibly                                   number of
            State               Present      Unknown      extirpated      Extirpated       Total      historical
                                                                                                       sites by
                                                                                                        state
----------------------------------------------------------------------------------------------------------------
Illinois....................  ...........  ...........  ..............               3            3            1
Indiana.....................  ...........  ...........  ..............               1            1          0.3
Iowa........................  ...........            4              24              13           41           14
Michigan....................           10            1  ..............               6           17            6
Minnesota...................  ...........           67              68               7          142           48
North Dakota................  ...........           10               6               1           17            6
South Dakota................  ...........           48  ..............              22           70           24
Wisconsin...................            3            1  ..............  ..............            4            1
Manitoba....................            1  ...........  ..............  ..............            1          0.3
                             -----------------------------------------------------------------------------------
    Total Number of                    14          131              98              53          296  ...........
     Historically Documented
     Sites..................
                             -----------------------------------------------------------------------------------
    Percent of the Total               5%          44%             33%             18%  ...........  ...........
     Number of Historical
     Sites by Occupancy.....
----------------------------------------------------------------------------------------------------------------

Illinois
    The Poweshiek skipperling historically occurred in Illinois, 
although only one historical occurrence is supported (Table 2). In the 
early 1870s, Dodge (1872, p. 218) reported abundant Poweshiek 
skipperling occupying ``the high rolling prairie that forms the divide 
between the Illinois and Rock rivers'' in Bureau County, Illinois. In 
addition to Bureau County, the Web site Butterflies and Moths of North 
America lists Poweshiek skipperling historical occurrences for Lake and 
Mason Counties, which were submitted to the Web site before the date 
field was required, so a default date of January 1, 1950, was assigned, 
which is outside of the typical flight period (http://www.butterfliesandmoths.org/species/Oarisma-poweshiek; accessed August 
16, 2012). The Web site maintains a verifiable database on species 
occurrences, but there is no accessible supporting data for the Lake 
and Mason Counties records (Lundh 2012, pers. comm.). Poweshiek 
skipperling is, therefore, presumed to be extirpated from Illinois.
Indiana
    There is one supported historical occurrence of Poweshiek 
skipperlings in Indiana (Table 2). Blatchley (1891, p. 898) reported 
small numbers of Poweshiek skipperlings near Whiting, Indiana; Shull 
(1987, p. 49) expressed confidence that this record is authentic. The 
Poweshiek skipperling is considered extirpated from Indiana.
Iowa
    Iowa historically contained approximately 14 percent (N= 41) of all 
known records of Poweshiek skipperlings rangewide (Table 2). The 
Poweshiek skipperling was historically known to occur at 38 sites in 13 
counties in Iowa (Nekola 1995, p. 8; Saunders 1995, pp. 27-28; Selby 
2005, p. 18; Nekola and Schlicht 2007, p. 7; Selby 2010, p. 6); 
however, this number may vary slightly (up to 41 sites) depending on 
how one divides sites along the Little Sioux River in the Freda-Cayler 
area (Selby 2012a, pers. comm.). Early reports from Parker (1870, p. 
271) described Poweshiek skipperling as abundant on a prairie slope at 
Grinnell, Iowa, while Lindsey (1917, p. 352; 1920, p. 320) noted 
additional rare occurrences in Story, Dickinson,

[[Page 63591]]

Poweshiek, and Woodbury Counties, Iowa--among these, habitat has long 
since been destroyed in all but Dickinson County.
    In 1993-1994, 65 sites were surveyed in 17 counties where Dakota 
skipper or Poweshiek skipperling had been previously recorded or where 
prairie and butterfly surveys or infra-red photography suggested the 
presence of Poweshiek skipperling habitat (Saunders 1995, pp. 7-8). 
Among the 65 sites surveyed, Poweshiek skipperlings were found at 29 
sites in 10 counties (Saunders 1995, p. 27). In 2000, Poweshiek 
skipperlings were found at six sites surveyed in and near Cayler 
Prairie and Freda Haffner Kettlehole state preserves in Dickinson 
County (Selby 2000, p. 19). Followup surveys of this complex in 2004, 
2005, and 2007, however, produced no confirmed sightings (Selby 2010, 
p. 6). Extensive surveys were conducted in 2007, and included 32 of the 
38 sites in the State with post-1990 records (Selby 2008, pp. 4, 6). 
Poweshiek skipperlings were found at 2 of the 38 sites surveyed--
Hoffman Prairie State Preserve in Cerro Gordo County and Highway 60 
Railroad Prairie in Osceola County (Selby 2008, pp. 6-7). Five of the 
six sites not included in the 2007 surveys had very little quality 
prairie (Selby 2012a, pers. comm.). Supplementary surveys conducted 
further west along U.S. Highway 18 in Hancock County also produced no 
confirmed sightings (Selby 2010, p. 7). No surveys were conducted at 
previously known Poweshiek skipperling sites in the State during the 
2012 flight season.
    The Poweshiek skipperling is presumed extirpated or possibly 
extirpated from all but four of the known sites in Iowa. The status of 
the Poweshiek skipperling is unknown at four sites: Highway 60 Railroad 
Prairie, Floete Prairie in Dickinson County, Florenceville Prairie, and 
Hayden Prairie in Howard County. There have been no surveys at Highway 
60 Railroad Prairie since the species was observed there in 2007 (Selby 
2012a, pers. comm.). The last observation of Poweshiek skipperling at 
Floete Prairie was in 1994 and the habitat ``did not appear to be very 
good quality'' in 2007, although the site was not surveyed for 
butterflies that year (Selby 2012a, pers. comm.) or in subsequent 
years. The Poweshiek skipperling was last observed at the Florenceville 
Prairie in 1994 (Saunders 1995, p. 27), but not during the 2007 survey 
year (Selby 2010, pp. 8-11). The species was last observed at Hayden 
Prairie in 2005, but not during surveys conducted in 2007 (Selby 2010, 
p. 10). Four Poweshiek skipperlings were found at Hoffman Prairie in 
Cerro Gordo County in 2008 (Selby 2009b, p. 3), but none were found 
during surveys in 2009 (Selby 2009b, p. 7) and 2010 (Selby 2010, p. 7). 
We initially assigned an unknown status to Hoffman Prairie site because 
the species had not been seen in the last two survey years; however, 
Selby believes that the species may be extirpated from this site (Selby 
2012a, pers. comm.), so we have assigned a status of extirpated to this 
site.
    To summarize, Poweshiek skipperling was historically documented in 
41 sites in Iowa. The species occupancy is unknown at 4 of those sites 
and the species is considered to be extirpated or possibly extirpated 
at 13 and 24 sites, respectively (Table 2). The species is not 
considered to be present at any of the sites in Iowa.
Michigan
    Michigan historically contained approximately 6 percent (N=17) of 
all known records of Poweshiek skipperlings rangewide (Table 2). 
Poweshiek skipperling has been historically documented at 17 sites in 6 
counties in Michigan. The species was first recorded in Michigan in 
1893 at Lamberton Lake near Grand Rapids in Kent County (Holzman 1972, 
p. 111) and then at nearby Button Lake Fen (also known as Emerald Lake 
Fen) in 1944 (McAlpine 1972, p. 83). Shrubs have invaded both sites, 
however, and no Poweshiek skipperlings have been found at either of 
these two western Michigan sites since 1944 and 1968, respectively 
(Michigan Natural Features Inventory 2011, unpubl. data). Holzman 
(1972, p. 111) documented Poweshiek skipperling in Oakland County in 
1970, and the species has since been found at a total of 15 locations 
in eastern Michigan.
    The Poweshiek skipperling is currently considered to be present at 
ten sites (Table 2) in four counties in Michigan: Jackson, Lenawee, 
Oakland, and Washtenaw. The species has been observed very recently 
(2007-2012) at most of those sites, except at the Liberty Bowl Fen in 
Jackson County, which has not been surveyed since one individual was 
observed in 1996. The status of the species is unknown at one site; 
Bullard Lake in Livingston County, where Poweshiek skipperling were 
last seen in 2007, but not in subsequent surveys in 2008 and 2009 
(Cuthrell 2012a, pers. comm.). The species is presumed extirpated from 
six sites including the only two sites in Kent County and three sites 
in Oakland County; Rattalee Road, Fenton Road, and Rattalee Lake Fen 
(Call C Burr Preserve) fens. The species has not been observed at the 
Rattalee Road and Fenton Road sites since 1970 and 1973, respectively 
(Michigan Natural Features Inventory 2011, unpubl. data). Four 
Poweshiek skipperlings were seen in 2009 at the Rattalee Lake Fen 
(Calla C Burr Preserve), but none were observed during surveys 
conducted in 2010, 2011, and 2012 (Cuthrell 2012a, pers. comm.; 
Michigan Natural Features Inventory 2011, unpubl. data). The Michigan 
Natural Features Inventory (MNFI) also considers the two sites in Kent 
County to be extirpated due to habitat loss and destruction, Lamberton 
Lake and Button Lake (also known as Emerald Lake); the species has not 
been observed at either site since 1968 and 1944, respectively. The 
species is presumed to be extirpated at Whalen Lake Fen in Livingston 
County, where the species has not been observed since 1998 despite 
three subsequent years of surveys (Michigan Natural Features Inventory 
2011, unpubl. data).
    Four of Michigan's ten extant (present) Poweshiek skipperling 
occurrences are considered to have at least good viability (Michigan 
Natural Features Inventory 2011, unpubl. data). Three of these sites 
(Buckthorn Lake (also known as Big Valley), Brandt Road Fen (also known 
as Holly Fen) and Long Lake Fen) are within 20 km (12 mi) of one 
another in Oakland County; all with relatively large numbers (61-389) 
of the species recorded in 2010-2012 surveys (Michigan Natural Features 
Inventory 2011, unpubl. data; Cuthrell 2012a, pers. comm.). The largest 
extant (present) Poweshiek skipperling population in Michigan is at 
Long Lake Fen, where 225 individuals (1.3/hr.) were counted during 2012 
surveys, down from 389 individuals (2.2/hr.) observed in the previous 
survey year with similar sampling effort. Long Lake Fen is likely the 
largest population of Poweshiek skipperling in the United States, and 
is subjected to intense development pressure. The fourth site, Grand 
River Fen (also known as Liberty Fen) in Jackson County, is 
approximately 100 km (62 mi) from the other three sites. In 2010, 
researchers counted 54 (0.3/hr.) Poweshiek skipperling at Grand River 
Fen, and 114 (0.6/hr.) in 2011 (Michigan Natural Features Inventory 
2011, unpubl. data; Cuthrell 2012a, pers. comm.). This number fell to 
14 (0.1/hr.) in 2012 (Cuthrell, 2012a, pers. comm.; 2012b, pers. 
comm.).
    Small populations, immediate threats that have significant impacts 
on the species, or both limit the viability of the remaining five sites 
where we consider Poweshiek skipperling to still be present

[[Page 63592]]

in Michigan. In 2010, eight (0.1/hr.) Poweshiek skipperling were 
recorded at Park Lydon in Washtenaw County; 12 individuals were counted 
in 2011 (0.1/hr.), and 22 were counted in 2012 (0.2/hr.) (Cuthrell 
2012a, pers. comm.). Two individuals (0.02/hr.) were recorded at Goose 
Creek Grasslands (also known as Little Goose Lake Fen) in Lenawee 
County in 2010, nine (0.07/hr.) were seen in 2011 (Cuthrell 2012a, 
pers. comm.; Cuthrell 2012b, pers. comm.). Only one Poweshiek 
skipperling was seen during a 15-minute 3-person survey in 2007 at the 
Snyder Lake site. Fourteen individuals were observed during 2008 
surveys at Halstead Lake Fen (Michigan Natural Features Inventory 2011, 
unpubl. data), and 18 were observed in 2012 (Cuthrell 2012a, pers. 
comm.); neither survey year had units of effort associated with the 
counts at this site. One individual was counted at Bullard Lake fen in 
2007, but the species was not observed in the two most recent survey 
years (2008 and 2009); therefore, the status is unknown at that site. 
We have only one year of data from Liberty Bowl Fen, where the species 
was recorded in 1996. The Eaton Road Fen is thought to be fairly 
viable, where 15-20 individuals were observed on multiple occasions in 
2005 and a high of 68 individuals were observed in 2011 (Cuthrell 
2013b, pers. comm.). The Eaton Road site is approximately 1 mi (0.6 km) 
from the Long Lake Fen site and is considered a sub-site within Long 
Lake Fen (Cuthrell 2013b, pers. comm.), but we consider it to be a 
separate site for the purposes of this rule.
    To summarize, Poweshiek skipperling was historically documented in 
17 sites in Michigan (Table 2). The species is considered to be present 
at 10 of the sites. The occupancy is unknown at 1 site, and the species 
is considered to be extirpated at 6 sites.
Minnesota
    Minnesota historically contained approximately 48 percent (N=142) 
of all known records of Poweshiek skipperlings rangewide (Table 2). 
There are approximately 189 historical Poweshiek skipperling occurrence 
records in 32 counties in Minnesota [Minnesota Natural Heritage 
Inventory (MN NHI) database accessed June 19, 2013, plus additional 
surveys]. Clusters of records occur within five general areas from the 
State's southwest corner to near the Canadian border in the north. 
Based on the proximity of some occurrences to one another (e.g., 
overlapping or occurrences in close proximity to one another in one 
general location), there appear to be approximately 142 distinct 
historical site records in the State (Dana 2012d, pers. comm; Service 
2013, unpubl. geodatabase). Poweshiek skipperling are presumed 
extirpated or possibly extirpated from at least 75 of these known 
sites. The status of the species is unknown at 67 sites, although 31 of 
those locations have not been surveyed since 2003, and the species has 
undergone a sharp decline in the State since then.
    Until about 2003, the Poweshiek skipperling was regarded as ``the 
most frequently and reliably encountered prairie-obligate skipper in 
Minnesota'' (Dana 2008, p. 1). Signs of the species' decline in 
Minnesota were noted in 2003 when Selby (2005, p. 20) found sharply 
lower numbers in and near Glacial Lakes State Park (Selby 2005, p. 20) 
compared to those observed in 2001 (Skadsen 2001, pp. 22-24). For 
example, numbers recorded along four transects that were surveyed in 
both years decreased from 104 to 2 individuals (Selby 2006b, Appendix 
2, p. ii). In 2004 and 2005, Selby (2006b, Appendix 2, p. 2) did not 
record a single Poweshiek skipperling on any of these transects in and 
around the park during 11 separate surveys.
    An extensive survey effort was conducted in 2007 and 2008 
throughout most of the species' known range in the State (Selby 2009a, 
entire). Sites with previous Poweshiek skipperling records that were 
considered to have the greatest conservation importance to the species 
(large, high-quality prairie remnants) were surveyed, as well as sites 
with no previous records that appeared likely to support the species 
(Selby 2009a, p. 2). In 2007, 70 sites in 15 counties were surveyed, 
including 26 sites with previous Poweshiek skipperling records (Selby 
2009a, pp. 1, 6). In 2008, 58 sites were surveyed in 13 counties, 
including 22 sites with prior records (Selby 2009a, pp. 1, 6). A total 
of 34 sites with previous Poweshiek skipperling records were surveyed 
in both years combined. Poweshiek skipperling presence was recorded on 
only three of the 70 surveyed sites in 2007; each of these three sites 
had just one confirmed individual (Selby 2009a, p. 1). The 2008 surveys 
documented no Poweshiek skipperling records on any of the 58 sites 
surveyed (Selby 2009a, p. 1).
    An extensive survey effort was also completed in 1993 and 1994 
(Schlicht and Saunders 1994, entire; Schlicht and Saunders 1995, 
entire). During those surveys, Poweshiek skipperlings were found in 11 
of 19 sites on which it had been previously recorded and in 13 new 
sites, for a total of 25 of 63 surveyed prairie sites; the species was 
present at 30 and 39 percent of the sites in 1993 and 1994, 
respectively (Schlicht and Saunders 1995, pp. 5-7). These results 
contrast sharply with those from the surveys conducted in 2007 and 
2008, when the species was found at four and zero percent of sites, 
respectively. Although the species was apparently more common in 1993 
and 1994, numbers of Poweshiek skipperling found during surveys were 
typically low. Large numbers were observed at only three sites 
(Schlicht and Saunders 1995, p. 4). At one of these sites, Glynn 
Prairie, 25 Poweshiek skipperling were recorded during a 50-minute 
survey in July 1993 (Schlicht and Saunders 1995, data sheet); no 
Poweshiek skipperling were observed at this site during the 2007 survey 
despite good survey conditions (Selby 2009a, p. xxxv).
    In 2007, multiple transect surveys were conducted in four sites 
with previously well-documented Poweshiek skipperling populations--
transects totaling 52,985 m (33 mi) were surveyed without observing a 
single Poweshiek skipperling (Dana 2008, p. 5). About half of these 
transects (totaling 20,959 m (13 mi)) were in Prairie Coteau Scientific 
and Natural Area (SNA), where in 1990 Selby recorded 116 Poweshiek 
skipperlings during the flight peak (Selby and Glenn-Lewin 1990, pp. 
19-20) along a total of about 6,250 m (4 mi) of transects (Dana 2008, 
p. 16). No Poweshiek skipperling were observed during surveys of the 
Prairie Coteau SNA in 2012 (Runquist 2012, pp. 9-10).
    Additional surveys were conducted in 2012, however, Poweshiek 
skipperling were not observed at any of the 18 sites with relatively 
recent records (Runquist 2012, pp. 4-25; Selby 2012, p. 2; Selby 2013, 
p. 2; Dana 2012c, pers. comm.; Runquist 2012a, pers. comm.; Olsen 
2012a, pers. comm.). Fifteen additional prairie sites with potential 
habitat or records of other skippers were surveyed in 2012, but no 
Poweshiek skipperling were observed (Runquist 2012, pp. 4-25; Selby 
2012, p. 2; Selby 2013, p. 2; Dana 2012c, pers. comm.; Runquist 2012a, 
pers. comm.; Olsen 2012a, pers. comm.).
    Nearly half (approximately 48 percent) of all documented Poweshiek 
skipperling sites rangewide are in Minnesota, thus the apparent 
collapse of large numbers of Poweshiek skipperling populations across 
the State may pose a significant challenge for the long-term existence 
of this species. Although the possibility remains that the species is 
extant at some sites where recent (2007, 2008, or 2012) surveys were 
negative, it seems unlikely that it is present at those sites in any 
significant numbers. Extensive surveys in 1993 and 1994 documented the 
species at about 35

[[Page 63593]]

percent of all surveyed sites, whereas the 2007 effort found them at 
only about 2 percent of all sites surveyed; no Poweshiek skipperling 
were detected despite widespread and robust survey efforts involving 
multiple observers in 2008 or 2012 (Dana 2008, p. 8; Selby 2009a, p. 1; 
Dana 2012c, pers. comm.; Runquist 2012a, pers. comm.; Olsen 2012, pers. 
comm.; Runquist 2012, pp. 4-25; Selby 2012, p. 2, 2013, p. 2).
    To summarize, Poweshiek skipperling was historically documented in 
approximately 142 sites in Minnesota (Table 2). The species is not 
considered to be present at any of these sites (Table 2). The occupancy 
is unknown at 67 sites, and the species is considered to be extirpated 
or possibly extirpated at 7 and 68 sites, respectively (Table 2).
North Dakota
    North Dakota historically contained approximately 6 percent (N=17) 
of all known records of Poweshiek skipperlings rangewide (Table 2). 
Poweshiek skipperlings have been historically documented at 17 sites 
(Table 2) in 7 North Dakota counties (Selby 2010, p. 18; Service 2013, 
unpubl. geodatabase): Cass, Dickey, LaMoure, Ransom, Richland, and 
Sargent in the southeastern corner of the State and Grand Forks County 
in the Northeast. Poweshiek skipperling are now considered extirpated 
or possibly extirpated from seven sites and four counties (Cass, 
Dickey, LaMoure, and Grand Forks) in North Dakota. The status of the 
species is unknown at 10 sites, where the species was last observed 
between 1996 and 2001, but not during the most recent 1-2 year(s) 
surveyed. The status of the species is also unknown at one site where 
the species was observed in 1996 with no recent surveys for the 
species, but the habitat was recently rated as poor (Service 2013, 
unpubl. geodatabase). Four sites with fairly recent Poweshiek 
skipperling records were surveyed in 2012; Poweshiek skipperling were 
not found at any of those sites (Royer and Royer 2012b, pp. 21-24; 
Royer and Royer 2012a, p. 6). One additional site was surveyed, which 
had the potential for Poweshiek skipperling presence because of its 
proximity to a known site for the species; however, no Poweshiek 
skipperling were found (Royer and Royer 2012b, pp. 18-19; Royer and 
Royer 2012a, p. 6; Royer 2012b, pers. comm.).
    The Poweshiek skipperling was known from seven North Dakota sites 
across six counties in the 1990s; however, only two of those sites were 
considered to have extant populations at that time; three records were 
represented by incomplete or ambiguous locality data and the species 
was assumed to be extirpated at one site (Royer and Marrone 1992b, pp. 
8-11). Surveys conducted in the State after 1992 documented additional 
populations, but the most recent surveys at these sites were mostly 
negative. Orwig discovered eight new populations of Poweshiek 
skipperling (six in Richland County and two in Sargent County) during 
three years of survey work (1995-1997) in southeast North Dakota (Orwig 
1995, pp. 3-4; Orwig 1996, pp. 4-6, 9-12; Orwig 1997, p. 2). The 
species was found at two of the eight sites surveyed in 1997 (Orwig 
1997, p. 2) and at two additional sites in 1996 (Spomer 2004, p. 11).
    Once abundant at several known sites in North Dakota, Poweshiek 
skipperlings have experienced a dramatic decline over the last few 
decades. In 1977, McCabe and Post (1977a, p. 38), for example, found 
Poweshiek skipperling to be abundant at McLeod Prairie in Ransom 
County, stating that they could ``be collected two at a time on the 
blossoms of Long-headed coneflower[hellip]'' In six years of subsequent 
monitoring (1986-1991), however, Royer failed to find a single 
Poweshiek skipperling at the site after it was converted to a cattle-
loading area (Royer and Marrone 1992b, p. 10). Royer and Marrone 
(1992b, pp. 10-11) assumed the species had been extirpated at this 
site. Similarly, the number of Poweshiek skipperlings recorded during 
surveys at the West Prairie Church site along the boundary of Cass and 
Richland counties, fell from hundreds in 1986, to four in 1990 and zero 
in 1991 and 2012 (Royer and Marrone 1992b, p. 8; Royer and Royer 2012b, 
p. 21). Poweshiek skipperlings are unlikely to persist at this small 
and isolated site (Royer and Royer 2012b, p. 21; Royer 2012c, pers. 
comm.).
    The last observation of a live Poweshiek skipperling in North 
Dakota was in 2001, at a new site discovered by Spomer (2001, p. 9) in 
Ransom County. Poweshiek skipperlings were not found in subsequent 
surveys at this site in 2002, 2003, and 2012 (Spomer 2001, p. 2; Spomer 
2002, p. 3; Spomer 2004 p. 36; Selby 2010, p. 18; Royer and Royer 
2012b, p. 22), although the 2012 survey may have been conducted too 
late in the year to detect the species at that site (Royer 2012b, pers. 
comm; Royer 2012d, pers. comm.). Therefore, the status of the species 
at this site is unknown.
    To summarize, Poweshiek skipperling was historically documented in 
17 sites in North Dakota (Table 2). The species is not considered to be 
present at any of these sites (Table 2). The occupancy is unknown at 10 
sites, and the species is considered to be extirpated or possibly 
extirpated at 1 and 6 sites, respectively (Table 2).
South Dakota
    South Dakota historically contained approximately 24 percent (N=70) 
of all known records of Poweshiek skipperlings rangewide (Table 2). The 
Poweshiek skipperling has been historically documented at approximately 
70 sites (Table 2) across 10 counties in South Dakota (Selby 2010, p. 
19). Based on expert review and additional survey and habitat 
information, the status of the species was determined to be unknown at 
48 sites and presumed extirpated at the remaining 22 sites (Table 2); 
at least 8 of the extirpated sites have been destroyed by conversion, 
gravel mining, loss of native vegetation, flooding, or heavy grazing 
(Skadsen 2012c, pers. comm.).
    The Poweshiek skipperling was not detected at any site that was 
surveyed between 2009 and 2012: 6 sites in 2009, 10 sites in 2010, 1 
sites in 2011, and 10 sites in 2012 (Skadsen 2009, p. 12; Skadsen 2011, 
p. 5; Skadsen 2010, pers. comm.; Skadsen 2012a, pers. comm.; Skadsen 
2012, p. 3). The 2009 to 2012 results are in marked contrast to surveys 
conducted in 2002 when the species was recorded at 23 of 24 sites 
surveyed (Skadsen 2003, pp. 11-45). Cool and wet weather may have 
depressed butterfly populations, in general, in eastern South Dakota 
and west-central Minnesota in 2009 as it apparently did in 2004 
(Skadsen 2004, p. 2; Skadsen 2009, p. 2).
Wisconsin
    Wisconsin historically contained approximately 1 percent (N=4) of 
all known records of Poweshiek skipperlings rangewide (Table 2). 
Naturalists reported Poweshiek skipperling to be common to abundant on 
prairies in southeastern Wisconsin in the late 1800s (e.g., in 
Milwaukee and Racine Counties), although exact localities are unknown 
(Borkin 2011, in litt.; Selby 2010, p. 22). By 1989, however, the 
species was listed as State endangered (Borkin 2011, in litt.). The 
Poweshiek skipperling is considered to be present at three sites in 
Wisconsin (Table 2); two sites are within the Southern Unit of the 
Kettle Moraine State Forest in Waukesha County. The third site, Puchyan 
Prairie State Natural Area (SNA), is approximately 100 km (62 mi) to 
the northwest of the Kettle Moraine State Forest in Green Lake County. 
The status of the species is unknown at another site within the

[[Page 63594]]

Kettle Moraine State Forest. An additional 2010 record of a butterfly 
was incorrectly identified as a Poweshiek skipperling at Melendy's 
Prairie Unit of the Scuppernong Prairie SNA (Borkin 2012b, pers. 
comm.).
    The two occurrences of Poweshiek skipperling in the Kettle Moraine 
State Forest inhabit small areas that were once part of a larger 
prairie complex, which was fragmented by conversion to agriculture, 
other human development, and encroachment of woody vegetation (Borkin 
2011, in litt.). The larger of the two populations at Kettle Moraine 
State Forest inhabits a 6-ha (15-ac) prairie remnant on Scuppernong 
Prairie SNA, which had record counts exceeding 100 individuals in 1994, 
1995, 1998, and 1999 (Borkin 1995a, p. 10; Borkin 1996, p. 7; Borkin 
2000b, p. 4; Borkin 2011, in litt.). Four were found in 2007 (Borkin 
2008, in litt., p. 1), although these data were collected during a 
single transect survey that may have been early in the flight season 
and are, therefore, not comparable to other survey years (Borkin 2012a, 
pers. comm.). A maximum count of 42, 17, 63, and 45 were counted in 
2009, 2010, 2011, and 2012, respectively (Borkin 2011a, pers. comm.; 
Borkin 2012c, pers. comm.). There was some concern that a controlled 
burn in late March of 2012 may correlate with lower numbers observed 
during the 2012 flight (Borkin 2012a, pers. comm.); however, this 
difference is within the range of variation observed over the previous 
four years (Wisconsin DNR 2012, in litt.).
    After brush was cleared from the area in 2002, a small number of 
Poweshiek skipperlings were discovered the following year in a small 
isolated prairie remnant patch at a second site in the Kettle Moraine 
State Forest, (Borkin in litt. 2008). Once the intervening woody growth 
was removed, individuals presumably dispersed from the Scuppernong SNA 
remnant prairie to a small habitat patch about 200 ft (61 m) away 
(Borkin 2012a, pers. comm.). Surveys at each habitat patch have 
consistently yielded counts of less than 10 (Borkin 2008, in litt.), 
with a combined high count of 11 to 15 individuals in 2011. A total of 
six individuals, with a high single day count of three, were observed 
in eight surveys during 2012 (Borkin 2012c, pers. comm.; Borkin 2012a, 
pers. comm.).
    The status of the Poweshiek skipperling is unknown at a third and 
much larger fragment of Kettle Moraine State Forest, the Kettle Moraine 
Low Prairie SNA, which is adjacent to the Wilton Road site. The Kettle 
Moraine Low Prairie SNA was overgrown by shrubs including willows 
(Salix spp.), quaking aspen (Populus tremuloides), and glossy buckthorn 
(Frangula alnus) and has been managed with a series of controlled 
burns, in addition to a 1975 wild fire (Borkin 2011, in litt; Borkin 
2012a, pers. comm.; Wisconsin DNR 2012, in litt). The highest number 
recorded at the Kettle Moraine Low Prairie SNA was 28 on July 8, 1995 
(Borkin 2012a, pers. comm.). Preliminary attempts in 2000 to 2003 to 
augment the population with adults from Scuppernong SNA and captive-
reared larvae were not successful (Borkin 2012a, pers. comm.). A single 
Poweshiek skipperling was sighted there on July 2, 2004, but none were 
found in surveys conducted in 2007-2009 and 2011-2012 (Borkin 2011b, 
pers. comm.; Borkin 2012a and 2012c, pers. comm.). Two Poweshiek 
skipperlings were recorded in 2010 at this site (Wisconsin DNR2012, in 
litt.); however, there were no photographs or voucher specimens to 
confirm the sighting. This site was surveyed less intensively than 
Scuppernong Prairie, because of the species' relatively low density and 
abundance at Kettle Moraine Low Prairie SNA (Borkin 2012a, pers. 
comm.). Extensive brush cutting, additional burns, and restoration of 
the hydrology have been undertaken in recent years (Borkin 2012a, pers. 
comm.).
    Poweshiek skipperlings are present at a third site in Wisconsin, 
Puchyan Prairie SNA, in Green Lake County, although this population is 
small and declining (Borkin 2009, pers. comm.). The Poweshiek 
skipperling was first discovered at Puchyan Prairie in 1995, and 6 to 
30 individuals have been recorded in subsequent surveys (Borkin 2008, 
in litt.; Swengel 2012, pers. comm). In 2012, Swengel (2012, pers. 
comm.) found a maximum of three individuals, despite several hours of 
searching over three days.
    Additional sites in eight counties (Crawford, Grant, Iowa, 
Jefferson, Monroe, Rock, Sauk, and Walworth) have been surveyed in an 
attempt to find undiscovered Poweshiek skipperling populations. Four of 
the eight sites surveyed in 1998 and 1999 seemed to have adequate host 
plants, nectar resources, and size typical of Poweshiek skipperling 
habitat, but Poweshiek skipperling were not present at any of the sites 
(Borkin 2000b, pp. 5-7).
    To summarize, Poweshiek skipperling was historically documented in 
4 sites in Wisconsin (Table 2). The species is considered to be present 
at three sites and the occupancy is unknown one site (Table 2).
Manitoba
    Manitoba historically contained less than 1 percent (N=1) of all 
known records of Poweshiek skipperlings rangewide (Table 2); however, 
multiple Poweshiek skipperling historical records occur in one general 
location--a complex of several nearby small sites within the Tallgrass 
Prairie Preserve--in far southern Manitoba, near the United States 
border. Poweshiek skipperlings were first recorded in Canada near Vita, 
Manitoba, in 1985 at each of seven prairies surveyed, and populations 
were described as abundant but localized (Catling and Lafontaine 1986, 
p. 63). Poweshiek skipperlings were found at 15 of 18 locations 
surveyed within the same area in 2002 (COSEWIC 2003, p. 5).
    The Poweshiek skipperling is currently present at one location in 
Canada, The Nature Conservancy's Tall Grass Prairie Preserve near Vita, 
Manitoba (Westwood 2010, p. 2; Westwood et al. 2012, p. 1; Hamel et al. 
2013, p. 1). Poweshiek skipperlings were historically moderately common 
in areas of the preserve (Klassen et al. 1989, p. 27). In 2002, Webster 
(2003, p. 5) counted approximately 150 individuals, and in 2006, 
approximately 126 individuals were sighted across 10 sites (Westwood 
2010, p. 3). Surveys of 10 sites in 2008 and 2009 yielded 281 and 79 
Poweshiek skipperlings, respectively (Dupont 2010, pers. comm.). 
Poweshiek skipperling numbers in the preserve declined sharply after a 
647-ha (1,600-ac) wildfire in fall 2009 burned much of the species' 
habitat, including areas that likely contained the largest and highest 
density populations (Westwood 2010, p. 2); surveys of comparable effort 
to the 2008 and 2009 surveys yielded only 13 Poweshiek skipperlings on 
the preserve in 2010 (Westwood 2010, pp. 7-22). Surveys of 45 sites 
within the Tall Grass Prairie Reserve during 2011 resulted in 13 sites 
with positive sightings, 9 of which were new sites (Westwood et al. 
2012, p. 11; Dupont 2011, pers. comm.). The average number of Poweshiek 
skipperlings found at each site ranged from 10 to 15 per hour. These 
numbers are up considerably from 2010, but not as high as observed in 
2008 (Dupont 2011, pers. comm.). In 2012, a total of 50 individuals 
were observed, which was ``low when compared to historic densities'' 
(Hamel et al. 2013, p. 17). The preserve has detailed management 
recommendations to facilitate recovery of the Poweshiek skipperling 
(Westwood 2010, p. 5).

[[Page 63595]]

    Following an assessment and status report completed in 2003 under 
the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), 
the Poweshiek skipperling was listed under the Species at Risk Act as 
Threatened in Canada in July 2005 (COSEWIC 2003). A recovery strategy 
is now in place for the species in Canada (Environment Canada 2012), 
which includes critical habitat designations within and adjacent to the 
Tall Grass Prairie Preserve (Environment Canada 2012, p. ii).

Summary of Factors Affecting the Species

    Section 4 of the Act (16 U.S.C. 1533), and its implementing 
regulations at 50 CFR Part 424, set forth the procedures for adding 
species to the Federal Lists of Endangered and Threatened Wildlife and 
Plants. Under section 4(a)(1) of the Act, we may list a species based 
on any of the following five factors: (A) The present or threatened 
destruction, modification, or curtailment of its habitat or range; (B) 
overutilization for commercial, recreational, scientific, or 
educational purposes; (C) disease or predation; (D) the inadequacy of 
existing regulatory mechanisms; and (E) other natural or manmade 
factors affecting its continued existence. Listing actions may be 
warranted based on any of the above threat factors, singly or in 
combination. Each of these factors is discussed below.
    We evaluated the level of impact to the population at each site of 
stressors at 170 Dakota skipper sites where the occupancy status of the 
site is considered to be present or unknown, as defined in the 
Background section of this rule. These 170 sites are found across the 
current range of the species in Minnesota, North Dakota, and South 
Dakota. Two Dakota skipper sites with an unknown or present occupancy 
were not evaluated. To determine the levels of impact to the population 
at each site, we used the best available and most recent information 
for each site, including reports, discussions with site managers, 
information from natural heritage databases, etc. (Service 2012, 
unpubl. data; Service 2013, unpubl. geodatabase). We only evaluated a 
stressor to the population at any one site if we had sufficient 
information to determine if the level of impact was high, medium, or 
low as defined for each stressor below; therefore, the number of sites 
evaluated varies with each stressor.
    We evaluated the level of impact to the species from stressors at 
68 Poweshiek skipperling sites where the occupancy status of the site 
is considered to be present or unknown, as defined in the Background 
section of this proposed rule. Although we did not evaluate every 
stressor at all 145 Poweshiek skipperling sites with present or unknown 
occupancy, the 68 sites that were evaluated are representative of all 
those sites in terms of geography (sites in Iowa, Michigan, Minnesota, 
North Dakota, South Dakota, and Wisconsin were evaluated), ownership, 
and management. To determine the levels of impact to the population at 
each site, we used the best available and most recent information, 
including reports, discussions with site managers, and information from 
natural heritage databases (Service 2012, unpubl. data; Service 2013, 
unpubl. geodatabase). We only evaluated a particular stressor at any 
one site if we had sufficient information to determine if the level of 
impact was high, medium, or low (as defined below); therefore, the 
number of sites evaluated varies with each stressor.

Factor A. The Present or Threatened Destruction, Modification, or 
Curtailment of Its Habitat or Range

    Habitat quality is a powerful determinant of extinction probability 
in butterflies such as the Dakota skipper and Poweshiek skipperling 
(Thomas et al. 2001, p. 1795). Among butterfly species in the United 
Kingdom, for example, equilibrium density of butterflies at sites with 
optimum habitat are from 25 to more than 200 times greater than those 
for occupied sites with suboptimal, yet suitable, habitat (Thomas 1984, 
cited in Thomas et al. 2001, p. 1794). Consistently good habitat 
quality is especially important for Dakota skipper and Poweshiek 
skipperling isolated populations, which would not be naturally 
recolonized if they were extirpated. Protection or restoration of 
habitat quality at these isolated sites is critical to the survival of 
both species, although stochastic events still pose some risk, 
especially for smaller populations and at small sites.
    The Poweshiek skipperling and Dakota skipper depend on a diversity 
of native plants endemic to tallgrass prairies and, for the Poweshiek 
skipperling in Michigan, prairie fens. When nonnative or woody plant 
species become dominant, Poweshiek skipperlings and Dakota skippers 
decline due to insufficient sources of larval food and nectar for 
adults. For example, at Wike Waterfowl Production Area in Roberts 
County, South Dakota, the extirpation of Poweshiek skipperling is 
attributed to the deterioration of native vegetation, in particular, 
the loss of nectar sources for adult butterflies due to invasive 
species encroachment (Skadsen 2009, p. 9).
    Destruction of native tallgrass and mixed-grass prairie began in 
1830 (Samson and Knopf 1994, pp. 418-419). Extant populations of Dakota 
skipper and Poweshiek skipperling are restricted to native prairie 
remnants and prairie fens; native prairies have been reduced by 85 to 
99.9 percent of their former area throughout the historical range of 
both species (Samson and Knopf 1994, pp. 418-419). Degradation and 
destruction of habitat occurs in many ways, including but not limited 
to: conversion of native prairie to cropland or development; ecological 
succession to woody vegetation; encroachment of invasive species; past 
and present fire, haying, or grazing management that degraded or 
destroyed the species' habitats; flooding; and, groundwater depletion, 
alteration, and contamination, which are discussed in further detail 
below.
    We evaluated the level of impact to the population at each site of 
several habitat-related stressors at 170 Dakota skipper sites where the 
occupancy status of the site is considered to be present or unknown, as 
defined in the Background section of this proposed rule (Table 3). 
These 170 sites are found across the current range of the species in 
Minnesota, North Dakota, and South Dakota. Two sites with an unknown or 
present occupancy were not evaluated. To determine the levels of impact 
to the population at each site, we used the best available and most 
recent information for each site, including reports, discussions with 
site managers, information from natural heritage databases, etc. 
(Service 2012, unpubl. data; Service 2013, unpubl. geodatabase). We 
only evaluated a stressor to the population at any one site if we had 
sufficient information to determine if the level of impact was high, 
medium, or low as defined for each stressor below. Similarly, the level 
of impact to the population was evaluated at 68 Poweshiek skipperling 
sites with present or unknown status (Table 4). Although we did not 
evaluate Factor A stressors at all 145 Poweshiek skipperling sites with 
present or unknown occupancy, the 68 sites that were evaluated are 
representative of all the present or unknown Poweshiek skipperling 
sites in terms of geography (range of the species, i.e., sites in Iowa, 
Michigan, Minnesota, North Dakota, South Dakota, and Wisconsin were 
evaluated), ownership, and management. Many sites for both species (59 
sites for Dakota skipper and 32 sites for Poweshiek skipperling) 
experience at least two habitat-related

[[Page 63596]]

stressors at a medium or high level of impact (Tables 3 and 4).

 Table 3--Number of Dakota Skipper Sites With Each Level of Impact and the Total Number of Sites That Were Rated
    for Each Type of Stressor--A Total of 170 Dakota Skipper Sites With Either Present or Unknown Status Were
 Examined; Only Sites With Sufficient Data for a Particular Stressor Were Rated as High, Medium, or Low (Service
                                 2012 Unpubl. Data; Service 2013, Unpubl. Data)
----------------------------------------------------------------------------------------------------------------
                                                                              Medium                    Total
                          Stressor                             High level    level of    Low level    number of
                                                               of impact      impact     of impact   rated sites
----------------------------------------------------------------------------------------------------------------
Destruction & Conversion (Agricultural & Nonagricultural                3           87           60          150
 Development)...............................................
Wind Development............................................            1            0            8            9
Flooding....................................................            0            6            6           12
Invasive Species............................................           13           31           18           62
Fire........................................................            9            4            6           19
Grazing.....................................................           10           29           14           53
Haying & Mowing.............................................            2           11           27           40
Lack of Management..........................................           10            5            3           18
Size/Isolation..............................................           50           35           58          143
Herbicide and/or Pesticide Use..............................            5            2            9           16
----------------------------------------------------------------------------------------------------------------


Table 4--Number of Poweshiek Skipperling Sites With Each Level of Impact and the Total Number of Sites That Were
Rated for Each Type of Stressor--A Total of 68 Poweshiek Skipperling Sites With Either Present or Unknown Status
   Were Examined; Only Sites With Sufficient Data for a Particular Stressor Were Rated as High, Medium, or Low
                             (Service 2012 Unpubl. Data; Service 2013, Unpubl. Data)
----------------------------------------------------------------------------------------------------------------
                                                                              Medium                    Total
                          Stressor                             High level    level of    Low level    number of
                                                               of impact      impact     of impact   rated sites
----------------------------------------------------------------------------------------------------------------
Destruction & Conversion (Agricultural & Nonagricultural                1           13           40           54
 Development)...............................................
Wind Development............................................            0            0            6            6
Flooding/Hydrology..........................................            2            4           14           20
Invasive Species............................................            9           30           12           51
Fire........................................................            7            3           14           24
Grazing.....................................................            7           14            2           23
Haying & Mowing.............................................            0            3            7           10
Lack of Management..........................................            5            6            2           13
Size/Isolation..............................................           25           24           19           68
Herbicide and/or Pesticide Use..............................            3            1            6           10
----------------------------------------------------------------------------------------------------------------

Destruction and Conversion of Prairies
Destruction and Conversion of Prairies to Agricultural Land
    Conversion of prairie for agriculture may have been the most 
influential factor in the decline of the Poweshiek skipperling and 
Dakota skipper since Euro-American settlement, but the threat of such 
conversion to extant populations is not well known and may now be 
secondary to other threats. By 1994, tallgrass prairie had declined by 
99.9 percent in Illinois, Iowa, Indiana, North Dakota, Wisconsin, and 
Manitoba; and by 99.6 percent in Minnesota; and 85 percent in South 
Dakota (Samson and Knof 1994, p. 419). Samson and Knof (1994, p. 419) 
did not provide a figure for the decline of tallgrass prairie in 
Saskatchewan, but mention an 81.3 percent decline in mixed grasses from 
historical levels. By 1994, mixed-grass prairie had declined from 
historical levels by 99.9 percent in Manitoba and 71.9 percent in North 
Dakota (Samson and Knof 1994, p. 419). Destruction of tallgrass and 
mixed-grass prairie began in 1830, but significant documentation of the 
ecosystem's butterfly fauna did not begin until about 1960. Therefore, 
most of the decline of the Dakota skipper and Poweshiek skipperling 
probably went unrecorded.
    Since about 1980, observers have documented the extinction of 
several populations of the Dakota skipper and Poweshiek skipperling due 
to habitat conversion to agricultural use in the United States and 
Canada. For example, four Dakota skipper sites in North Dakota were 
converted to irrigated potato fields, and one in South Dakota was 
converted for crop production (Royer and Marrone 1992a, p. 17). The 
Fannystelle site in Manitoba, where the Dakota skipper was last 
recorded in 1991, was subsequently converted for row-crop agriculture 
(Webster 2003, p. 7). In North Dakota, further conversion is a threat 
to Dakota skippers in the important Towner-Karlsruhe complex (Royer and 
Royer 1998, p. 22; Lenz 1999b, p. 13), where the flat topography and 
high water table facilitate conversion to irrigated crop production. 
Populations of Dakota skipper in Manitoba typically occupy flat terrain 
that may be vulnerable to conversion to cropland, although soil 
conditions may be unsuitable for row crops at some of these sites 
(Webster 2003, p. 10). Similarly, conversion of native prairie to 
cropland continues to be a threat to Poweshiek skipperling habitat 
throughout its range (Royer and Marrone 1992b, p. 17).
    The Dakota skipper, and until recently, the Poweshiek skipperling, 
have largely persisted in areas that are relatively unsuitable for row 
crop agriculture because of their steep terrain (e.g., in the Prairie 
Coteau of South Dakota) or where soils are too wet or rocky for row-
crop agriculture (McCabe 1981, pp. 189-190, Webster 2003, p. 10). 
Densely spaced, large glacial rocks, for example, may have deterred 
cultivation

[[Page 63597]]

at the Chippewa Prairie in Minnesota and ``spared Chippewa Prairie in 
Minnesota from the plow'' (Dana 2012, pers. comm.). In areas where 
Poweshiek skipperling and Dakota skipper habitat persists but is 
adjacent to agriculture, added nutrients from agricultural runoff 
affects groundwater and additional nutrients in the system contribute 
to the dominance of invasive plants (Fiedler and Landis 2012, p. 51: 
Michigan Natural Features Inventory 2012, p. 4).
    In summary, conversion for agriculture on lands suitable for such 
purposes is a current, ongoing stressor of high level of impact to the 
Poweshiek skipperling and Dakota skipper populations in areas where 
such lands still remain. Advances in technology may also increase the 
potential of conversions in areas that are currently unsuitable for 
agriculture.
    We rated the level of impact to the populations of the stressor 
posed by habitat destruction or conversion for both agriculture and 
nonagricultural purposes (except for conversion for wind energy 
development, which was analyzed separately) at 150 Dakota skipper and 
54 Poweshiek skipperling sites with present or unknown status (see 
Tables 3 and 4) where we had sufficient information to evaluate the 
stressor. In our evaluation of this stressor, we combined agricultural 
and nonagricultural impacts--our analyses are discussed below (see 
Destruction and Conversion of Prairies due to Nonagricultural 
Development).
Destruction and Conversion of Prairies to Nonagricultural Development
    Conversion of prairie for nonagricultural land uses, such as energy 
development, gravel mining, transportation, and housing are stressors 
to both Poweshiek skipperling and Dakota skipper populations. For 
example, a site where the Dakota skipper and Poweshiek skipperling were 
recorded in 1997 (Skadsen 1997, pp. 15-16, B-1) in the Bitter Lake area 
of Day County, South Dakota, is now a gravel pit, and the species' 
habitat no longer exists there (Skadsen 2003, pp. 47-48).
    Almost all prairie remnants with Poweshiek skipperling and Dakota 
skipper populations are associated with gravelly glacial till soils 
(Service 2013, unpubl. geodatabase); therefore, gravel mining is a 
potential stressor to populations at a large number of sites. Gravel 
mining is a stressor to Poweshiek skipperling and Dakota skipper 
populations at several sites in Minnesota (Dana 1997, p. 15). For 
example, gravel mining is a threat in at least three of the five sites 
that comprise the Felton Prairie complex (Cochrane and Delphey 2002, 
pp. 16-17); however, the Clay County Stewardship Plan (Felton Prairie 
Stewardship Committee 2002) may have reduced the likelihood of the 
gravel mining stressor to populations at this complex. On at least 
seven sites in Minnesota, Dakota skippers inhabit northern dry prairie 
plant communities, which are generally impacted by gravel mining due to 
the predominance of gravel soils (Minnesota DNR 2006, p. 221). Gravel 
mines are considered a stressor with a high level of impact to 
populations of both species because, where it occurs, the habitat is 
completely destroyed.
    Energy development (oil, gas, and wind) and associated roads and 
facilities result in the loss or fragmentation of suitable prairie 
habitat (Reuber 2011, pers. comm.). Much of the Dakota skipper's range 
and some of the Poweshiek skipperling's range overlaps with major areas 
of oil and gas development, which have been increasing rapidly in parts 
of both species' ranges. North Dakota, for example, is now one of the 
top two oil-producing states in the United States, and new development 
is occurring rapidly (MacPherson 2012, p. 1; North Dakota Petroleum 
Council 2012, p. 1). The number of drilling permits in North Dakota 
nearly doubled between 2007 and 2008, from 494 permits issued in 2007 
to 946 in 2008 (North Dakota Petroleum Council 2009, p. 2). Permits 
dropped to 627 in 2009 (North Dakota Petroleum Council 2010, p. 2), but 
increased dramatically to 1,676 in 2010 (Ogden 2011, p. 1). While much 
of the oil activity is currently occurring in areas of native prairie 
overlaying the Bakken and Three Forks formations to the west of known 
locations for both species, mineral exploration has occurred in all but 
one county in North Dakota (North Dakota Petroleum Council 2012, p. 1). 
McKenzie County falls in the center of this development and McHenry 
County is also within these formations (Mueller 2013, pers. comm.). The 
oil development on the Bakken formation in North Dakota, for example, 
is a future stressor to Dakota skipper populations in McKenzie County 
(Royer and Royer 2012b, p. 16). Oil company officials anticipate that 
production will continue to expand at record levels (MacPherson 2012, 
p. 1; MacPherson 2010, entire).
    Native prairie habitat would be destroyed in the footprint of an 
oil and gas well pad, but the pads are relatively small. However, each 
oil and gas well pad requires new road construction, and evidence 
suggests that Poweshiek skipperlings may avoid crossing roads (Westwood 
et al. 2012, p. 18). Oil and gas development can double the density of 
roads on range lands (Naugle et al. 2009, pp. 11, 46), increase 
pipelines, and increase the number of gravel pits to accommodate the 
increased road construction (Mueller 2013, pers. comm.). In areas with 
ranching, tillage agriculture, and oil and gas development, 70 percent 
of the developed land was within 100 m (109 yards (yd)), and 85 percent 
of the developed land was within 200 m (218 yd), of a human structure 
(Naugle et al. 2009, p. 11). Researchers estimated that in those areas, 
every square km (0.39 square miles) of land may be both bounded by a 
road and bisected by a power line (Naugle et al. 2009, p. 11). The 
habitat fragmentation associated with oil and gas development may 
amplify other threats to both species, such as the effects of 
population isolation and the impacts of stochastic events.
    Energy development has additional undesirable and potentially 
significant cumulative impacts on wildlife. Catastrophic events, such 
as oil and brine spills, could cause direct mortality of Dakota skipper 
or Poweshiek skipperling larvae that are in shelters at or below the 
soil surface. Such spills may also cause the loss of larval host and 
nectar plants in the spill path. Additional plants may be lost during 
spill response, particularly if the response involves burning. No such 
spills are known to have occurred in the region, however, and the 
likelihood of spills occurring on the small fraction of land that 
remains native tallgrass prairie in North Dakota (less than one percent 
according to Samsom and Knoff 1994, p. 419) is low.
    Wind energy turbines and associated infrastructure (e.g., 
maintenance roads) are likely stressors to Dakota skipper and Poweshiek 
skipperling populations, particularly on private land in South Dakota 
(Skadsen 2002, p. 39; Skadsen 2003, p. 47; Skadsen 2012d, pers. comm.). 
Similar to oil and gas development, wind development would destroy 
native prairie habitat in the footprint of the structure, add access 
roads and other infrastructure that may further fragment prairies, and 
could be catalysts for the spread of invasive species. Further, it is 
unknown if the noise and flicker effects associated with wind turbines 
may impact Dakota skipper or Poweshiek skipperling populations beyond 
direct impacts from the turbines and/or infrastructure. Other wildlife 
species, such as birds, have shown significant avoidance of grasslands 
where wind development has occurred (Pruett et al. 2009, p. 1256;

[[Page 63598]]

Shaffer et al. 2012, p.). Wind development was assessed at nine Dakota 
skipper sites and six Poweshiek skipperling sites where we had 
sufficient information. The level of threat was considered to be low at 
most sites because although the site may be in an area with the 
potential for wind development, there are no specific plans or 
proposals to develop wind power on the site. Wind development is 
considered a stressor of high level of impact to populations at sites 
where development is proposed and there are no actions or plans to 
mitigate impacts to the species. For example, a wind facility was 
recently proposed at a Dakota skipper site in South Dakota (Skadsen 
2012d, pers. comm.), which poses a high-level threat for the species at 
that site because there are no plans to mitigate impacts of habitat 
destruction. Although wind power development currently poses a high 
level of impact to the population at only one site, the extent of this 
threat will likely increase in the future, due to the high demand for 
wind energy and the number of Dakota skipper and Poweshiek skipperling 
sites that are conducive to wind development (e.g., Skadsen 2003, pp. 
47-48). Furthermore, power distribution lines may be developed in order 
to accommodate the added power of wind farms, for instance, a new power 
line is currently being planned in the Prairie Coteau in South Dakota 
for that purpose (Mueller 2013, pers. comm.).
    Housing construction has likely contributed to the loss of at least 
two Poweshiek skipperling populations in Michigan, and the largest 
extant population in Michigan is located in an area under intense 
development pressure (Michigan Natural Features Inventory 2011, unpubl. 
data). Residential wells and drainage disrupt prairie fen hydrology by 
reducing water levels and thus, facilitating rapid growth of woody 
vegetation. In addition, nutrients added to the groundwater from 
leaking septic tanks contribute to the dominance of invasive plants, 
such as narrow-leaved cattail (Typha angustifolia) and red canary grass 
(Phalaris arundinacea) (Michigan Natural Features Inventory 2012, p. 
4).
    Road construction impacts Poweshiek skipperling and Dakota skipper 
habitat because it increases the demand for gravel, and as a result of 
routine maintenance (e.g., broadcast herbicide applications, early 
mowing, and cleaning out ditches), improvements (e.g., widening roads 
or converting two-lane highways to four-lane highways), or new 
construction. Poweshiek skipperling habitat was destroyed or degraded 
on at least two private properties in Roberts County, South Dakota, for 
example, in association with the widening of U.S. Highway 12 (Skadsen 
2003, p. 47). Roadside prairie remnants can help support populations of 
both species and serve as dispersal corridors between larger remnants; 
therefore, loss of these areas to road expansion or construction 
further reduces and fragments remaining habitat.
    In summary, nonagricultural development, such as gravel mining, 
activities associated with energy development, or housing and road 
development, poses a current stressor of moderate to high impact to 
populations on those lands that are not protected from destruction or 
conversion through a conservation easement or fee title ownership by a 
conservation agency. This type of development may become more 
widespread as such practices increase in the future.
    As discussed above in Destruction and Conversion of Prairies to 
Agricultural Land, we rated the level of impact to the populations of 
the stressor posed by habitat destruction or conversion for both 
agriculture and nonagricultural purposes combined (except for 
conversion for wind energy development, which was analyzed separately) 
at 150 Dakota skipper sites with present or unknown status (see Table 
3) where we had sufficient information to evaluate the stressor. The 
level of impact of each stressor to the population at each site is high 
at three of those sites, due to ongoing destruction of the native 
prairie or there was a high likelihood of conversion because it is 
located close to other converted areas and the land is conducive for 
agriculture. The level of threat is high at 3 sites, moderate at 87 
sites, and 60 sites are protected from destruction or conversion 
through a conservation easement or fee title ownership by a 
conservation agency (Table 3). This stressor occurs across the range of 
the Dakota skipper; the stressor has a medium to high level of impact 
to Dakota skipper populations in Minnesota, North Dakota, South Dakota, 
Manitoba, and Saskatchewan. The level of impact was considered to be 
low if the site is protected from destruction or conversion by fee 
title ownership by a governmental conservation agency, nongovernmental 
conservation organization (e.g., The Nature Conservancy), or 
educational institution (e.g., South Dakota State University). 
Similarly, 54 Poweshiek skipperling sites with present or unknown 
status were assessed that had sufficient information: The level of 
threat was high at one site and moderate at 13 sites, and 40 sites are 
protected from destruction or conversion through a conservation 
easement or fee title ownership by a conservation agency (Table 4). At 
least 5 of the 14 sites where the Poweshiek skipperling is considered 
to still be present have a medium risk of conversion. This stressor 
occurs across most of the Poweshiek skipperling range; the stressor has 
a medium to high level of impact to Poweshiek skipperling populations 
in Iowa, Michigan, Minnesota, and South Dakota; the level of impact is 
low for the species at the Manitoba location.
Fluctuating Water Levels
    Flooding is a threat to Poweshiek skipperlings and Dakota skippers 
at sites where too much of the species' habitat is flooded or where 
patches are flooded too frequently. Poweshiek skipperlings and Dakota 
skippers must either survive flooding events in numbers sufficient to 
rebuild populations after the flood or recolonize the area from nearby 
areas that had not flooded. In addition, the return interval of floods 
must be infrequent enough to allow for recovery of the populations 
between floods. Changes in hydrology resulting from wetland draining 
and development may permanently alter the plant community and, 
therefore, pose a threat to Poweshiek skipperling and Dakota skipper 
due to loss of larval food and nectar sources.
    The Dakota skipper and Poweshiek skipperling are presumed 
extirpated from several sites due to flooding or draining. For example, 
one Dakota skipper site was lost to flooding due to rising water levels 
at Bitter Lake, South Dakota (Skadsen 1997, p. 15). At Whalen Lake Fen 
in Michigan, dredging and channelization disrupted the hydrology of the 
site and the fen has since been invaded by glossy buckthorn and narrow 
leaf cattail; Poweshiek skipperlings are presumed to be extirpated from 
the site (Michigan Natural Features Inventory 2011, unpubl. data).
    Fluctuating water levels are a current stressor to populations 
across both species' ranges. Loss of habitat or direct mortality due to 
fluctuating water levels, such as permanent flooding or wetland 
draining is a current stressor to populations in at least 12 Dakota 
skipper sites with present or unknown status and 20 Poweshiek 
skipperling sites with present or unknown status. For example, one of 
the three sites with present or unknown status of Poweshiek skipperling 
in Wisconsin, Puchyan Prairie, is subject to flooding--the entire 
prairie portion of the site was

[[Page 63599]]

submerged in 1993 (Hoffman 2011, pers. comm.; Wisconsin DNR 2012, in 
litt). The number of Poweshiek skipperling observed at that site is 
consistently low. Flooding is a likely factor that has contributed to 
the low numbers observed in at least part of this site (Borkin 2012c, 
pers. comm.).
    Conversely, groundwater disruption and draining is a stressor at 
all 10 of the Michigan prairie fen Poweshiek skipperling sites where 
the species is present and one with unknown occupancy (Service 2013, 
unpubl. data). Interrupted groundwater flow-through fens can reduce 
water levels and facilitate woody vegetation establishment and growth 
(Michigan Natural Features Inventory 2012, p. 4). Agricultural and 
residential drains and wells can lower the groundwater table, thereby 
reducing the supply of calcareous seepage, which is an essential 
underlying component of prairie fen hydrology (Michigan Natural 
Features Inventory 2012, p. 4). Furthermore, nutrient additions 
associated with drain fields can contribute to invasive species 
encroachment. For instance, if groundwater flow to prairie wetlands is 
severed, fen habitats may convert from native grasses and flowering 
forbs to habitats dominated by invasive species or woody vegetation 
(Fiedler and Landis 2012, p. 51, Michigan Natural Features Inventory 
2012, p. 4). The site with the highest number of Poweshiek skipperlings 
in Michigan, for instance, is partially bordered by residential areas 
and is under intense development pressure (Michigan Natural Features 
Inventory 2011, unpubl. data). At least 8 of the 11 fen sites with 
present or unknown status are at least partially unprotected from 
development, and at least 7 of those are closely bordered by roads, 
agriculture, or residential developments (Michigan Natural Features 
Inventory 2011, unpubl. data; Service 2013, unpubl. geodatabase). The 
status of Poweshiek skipperling is unknown at one fen site where the 
hydrology was likely disrupted by roads and extensive residential 
development in close proximity to the fen (Michigan Natural Features 
Inventory 2011, unpubl. data).
    The level of impact to populations due to flooding was assessed at 
12 Dakota skipper sites with present or unknown status that had 
sufficient information to evaluate the stressor (Table 3); this 
evaluation only included sites in North and South Dakota. Flooding is a 
stressor of moderate-level impact to populations at 6 of the sites, 
where there is evidence of recent or pending decrease in the quality or 
extent of suitable habitat at the site due to a change in wetland 
vegetation, wetland hydrology, or flooding--all of these sites occur in 
North Dakota (Service 2012 unpubl. data; Service 2013, unpubl. data). 
Similarly, we assessed 20 Poweshiek skipperling sites with present or 
unknown occupancy for the level of impact to populations due to water 
fluctuations (e.g., flooding or draining) where we had sufficient 
information to evaluate the stressor (Table 4). Flooding is a stressor 
with moderate impact to the populations at 3 Poweshiek skipperling 
sites (including a site in Wisconsin--one of the 14 Poweshiek 
skipperling sites with a present status), and changes to hydrology is a 
stressor of moderate- to high-level impact to populations at all 11 
Michigan sites (including 10 of 14 Poweshiek skipperling sites that 
have a present status) and 1 site in North Dakota (Service 2012 unpubl. 
data; Service 2013, unpubl. data).
    In summary, fluctuating water levels is a current and ongoing 
stressor of moderate level of impact to populations where the habitat 
may be temporarily lost due to intermittent flooding and is a threat of 
high severity where a change in hydrology may completely degrade the 
habitat quality of a site, particularly prairie fens.
Invasive Species and Secondary Succession
    Poweshiek skipperlings and Dakota skippers typically occur at sites 
embedded in agricultural or developed landscapes, which make them more 
susceptible to nonnative or woody plant invasion. Nonnative species 
including leafy spurge, Kentucky bluegrass, alfalfa, glossy buckthorn, 
smooth brome, purple loosestrife (Lythrum salicaria), Canada thistle 
(Cirsium arvense), reed canary grass, and others have invaded Poweshiek 
skipperling and Dakota skipper habitat throughout their ranges (Orwig 
1997, pp. 4, 8; Michigan Natural Features Inventory 2011, unpubl. data; 
Skadsen 2002, p. 52; Royer and Royer 2012b, pp. 15-16, 22-23). Leafy 
spurge and Kentucky bluegrass have been cited as one of the major 
threats to native prairie habitat at several public and privately owned 
Dakota skipper sites in North Dakota (Royer and Royer 2012b, pp. 15-16, 
22-23; Royer 2012, pers. comm.). Once these plants invade a site, they 
replace or reduce the coverage of native forbs and grasses used by 
adults and larvae of both butterflies. Leafy spurge displaces native 
plant species, and its invasion is facilitated by actions that remove 
native plant cover and expose mineral soil (Belcher and Wilson 1989, p. 
172). The seasonal senescence patterns (timing of growth) of grass 
species as they relate to the larval period of Dakota skippers 
determine which grass species are suitable larval host plants. Exotic 
cool season grasses, such as Kentucky bluegrass and smooth brome, are 
not growing when Dakota skipper and Poweshiek skipperling larvae are 
feeding, thus a prevalence of these grasses reduces food availability 
for the larvae.
    The stressor from nonnative invasive herbaceous species is 
compounded by the encroachment of woody species into native prairie 
habitat. Glossy buckthorn and gray dogwood encroachment, for example, 
is a major stressor to Poweshiek skipperling populations at the Brandt 
Road Fen in Michigan, which supports the second largest population of 
Poweshiek skipperlings in the State (Michigan Natural Features 
Inventory 2011, unpubl. data). Invasion of tallgrass prairie and 
prairie fens by woody vegetation such as glossy buckthorn reduces light 
availability, total plant cover, and the coverage of grasses and sedges 
(Fiedler and Landis 2012, pp. 44, 50-51). This in turn reduces the 
availability of both nectar and larval host plants for Poweshiek 
skipperlings and Dakota skippers. If groundwater flow to prairie 
wetlands is disrupted (e.g., by development) or intercepted (e.g., 
digging a pond in adjacent uplands or installing wells for irrigation 
or drinking water), it can quickly convert to shrubs or other invasive 
species (Fiedler and Landis 2012, p. 51; Michigan Natural Features 
Inventory 2012, p. 4). For example, roads and residential development 
likely disrupted the hydrology of a prairie fen where the Poweshiek 
skipperling was last observed in 2007 and where 2008 and 2009 surveys 
for Poweshiek skipperlings were negative (Michigan Natural Features 
Inventory 2011, unpubl. data). Furthermore, on some sites, land 
managers intentionally facilitated succession of native-prairie 
communities to woody vegetation or trees, such as Ponderosa pine (Pinus 
ponderosa) or spruce (e.g., Dana 1997, p. 5). This converts prairie to 
shrubland, forest, or semi-forested habitat types and facilitates 
invasion of adjacent native prairie by exotic, cool-season grasses, 
such as smooth brome. Moreover, the trees and shrubs provide perches 
for birds that may prey on the butterflies (Royer and Marrone 1992b, p. 
15; 1992a, p. 25).
    We rated the level of impact to populations of invasive species at 
62 Dakota skipper sites and 51 Poweshiek skipperling sites that had 
sufficient information to evaluate the stressor (Table 3 and Table 4; 
Service 2012

[[Page 63600]]

unpubl. data; Service 2013, unpubl. data). This stressor is considered 
to have a low level of impact to the populations if there was either no 
information to indicate a stressor or management was ongoing to control 
invasive species using methods that are unlikely to cause adverse 
effects to Dakota skippers or Poweshiek skipperlings (e.g., spot-
spraying or hand-pulling). Sites were assigned a moderate level of 
impact to populations if invasive species are typically a primary 
driver of management actions and make it difficult for managers to 
specifically tailor management to conserve Dakota skipper or Poweshiek 
skipperling habitat. The site was assigned a high level of impact to 
populations if one or more nonnative invasive plant species are 
abundant or increasing and management activities are not being 
implemented to control their expansion; or if necessary management 
actions cannot be implemented without themselves causing an additional 
stressor to the Dakota skipper or Poweshiek skipperling populations at 
the site.
    Invasive species are a current and ongoing stressor with high 
levels of impact to Dakota skipper and Poweshiek skipperling 
populations on sites where land management is conducive to their 
invasion or expansion or where they have become so pervasive that even 
favorable management may not be quickly effective. Succession is a 
current and ongoing stressor of moderate-level impact to populations at 
sites where management is insufficient. The stressor of invasive 
species to populations on small and isolated sites (e.g., Big Stone 
NWR) is a current and ongoing stressor of high level of impact to 
populations, because Dakota skipper and Poweshiek skipperling 
populations have little resilience to the resulting habitat degradation 
and to the often aggressive management needed to control the invasive 
plants. Loss of habitat or degradation of the native plant community 
due to encroachment of invasive species or woody vegetation is 
considered a high level of impact to populations at 13 of the 62 
assessed Dakota skipper sites, a moderate level of impact to 
populations at 31 sites, and low impact to populations at 18 sites. 
Sites with high and moderate level of impact occur throughout the 
species range in Minnesota, North and South Dakota (Service 2012 
unpubl. data; Service 2013, unpubl. data). Similarly, invasive species 
are a stressor of high level of impact to populations at 9 of the 51 
evaluated Poweshiek skipperling sites, moderate of level impact to 
populations at 30 sites, and low level of impact to populations at 12 
sites--sites with high and moderate levels of impact are throughout the 
range of the species in Iowa, Minnesota, Michigan, North Dakota, South 
Dakota, Wisconsin, and Manitoba and include at least 11 of the 14 sites 
where the species is still present (Service 2013, unpubl. data).
Fire
    Dakota skipper and Poweshiek skipperling populations existed 
historically in a vast ecosystem maintained in part by fire. Due to the 
great extent of tallgrass prairie in the past, fire and other intense 
disturbances (e.g., locally intensive bison grazing) likely affected 
only a small proportion of the habitat each year, allowing for 
recolonization from unaffected areas during the subsequent flight 
period (Swengel 1998, p. 83). Fire can improve Poweshiek skipperling 
(Cuthrell 2009, pers. comm.) and Dakota skipper habitat (e.g., by 
helping to control woody vegetation encroachment), but it may also kill 
most or all of the individuals in the burned units and alter entire 
remnant prairie patches, if not properly managed (e.g., depends on the 
timing, intensity, etc.). Accidental wildfires also may burn entire 
prairie tracts (Dana 1997, p. 15) and may hamper plans to carefully 
manage Dakota skipper and Poweshiek skipperling habitat. A human-set 
wildfire in late fall 2009 and another extensive fire in 2011, for 
example, burned considerable amounts of good prairie habitat in 
Manitoba's Tall Grass Prairie Preserve (Hamel et al. 2013, p. 1; 
Westwood 2010, pers. comm.), which is the only location in Canada where 
Poweshiek skipperlings are present; Dakota skippers are extirpated from 
the site. The fires at the Tall Grass Prairie Preserve may have killed 
overwintering larvae, and the population of Poweshiek skipperling in 
Canada ``may have been greatly reduced as a result of these fires'' 
(Hamel et al. 2013, p. 1).
    Intentional fires, without careful planning, may also have 
significant adverse effects on populations of Dakota skippers and 
Poweshiek skipperlings, especially after repeated events (McCabe 1981, 
pp. 190-191; Dana 1991, pp. 41-45, 54-55; Swengel 1998, p. 83; Orwig 
and Schlicht 1999, pp. 6, 8). In systematic surveys of Minnesota 
tallgrass prairies, for example, Dakota skippers were less abundant on 
sites that had been burned, compared with otherwise similar hayed sites 
(Swengel 1998, p. 80; Swengel and Swengel 1999, pp. 278-279). 
Similarly, Schlicht (1997b, p. 5) counted fewer Dakota skippers per 
hour in burned than on grazed sites in Minnesota. Orwig and Schlicht 
(1999, p. 8) speculated that inappropriate use of prescribed burning 
eliminated Dakota skippers from the last known occupied site in Iowa, a 
65-ha (160-ac) preserve. At Prairie Coteau Preserve in Minnesota, 
Schlicht (2001a, pp. 9-10) found greater flower abundance on regularly 
burned than rarely burned sites, but Dakota skipper abundance showed 
the greatest decline on the burned sites.
    The effects of fire on prairie butterfly populations are difficult 
to ascertain (Dana 2008, p. 18), but the apparent hypersensitivity of 
Poweshiek skipperlings and Dakota skippers indicates that it is a 
threat to both species in habitats burned too frequently or too 
broadly. The Poweshiek skipperling and Dakota skipper are not known to 
disperse widely (Swengel 1996, p. 81; Burke et al. 2011, p. 2279); 
therefore, in order to reap the benefits of fire to habitat quality, 
Poweshiek skipperlings and Dakota skippers must either survive in 
numbers sufficient to rebuild populations after the fire or recolonize 
the area from a nearby unburned area. In addition, the return interval 
of fires needs to be infrequent enough to allow for recovery of the 
populations between burns. Therefore, fire is a threat to Poweshiek 
skipperlings and Dakota skippers at any site where too little of the 
species' habitat is left unburned or where patches are burned too 
frequently.
    Panzer (2002, p. 1306) identified four life-history traits of duff-
dwelling insects such as the Dakota skipper and Poweshiek skipperling 
that were good predictors of a negative response to fire: (1) Remnant 
dependence (occurring as small, isolated populations); (2) upland 
inhabitance (dry uplands burn more thoroughly than wetter habitats); 
(3) nonvagility (low recolonization rate); and (4) univoltine (slower 
recovery rates for species with only one generation per year). Species 
exhibiting all four traits should be considered ``hypersensitive'' to 
fire (Panzer 2002, p. 1306). The Poweshiek skipperling and Dakota 
skipper meet all of Panzer's criteria for hypersensitivity (Panzer 
2002, p. 1306) and have additional life history traits that further 
suggest hypersensitivity to fire. Panzer (2002) observed mean declines 
of 67 percent among fire-negative species, although actual mortality 
was likely higher due to some immigration into experimental areas after 
the burn. When all or large portions of prairie remnants are burned, 
many or all prairie butterflies may be eliminated at once. Complete

[[Page 63601]]

extirpation of a population, however, may not occur after a single burn 
event (Panzer 2002, p. 1306) and the extent of effects would vary 
depending on time of year and fuel load.
    Poweshiek skipperlings lay their eggs near the tips of leaf blades, 
and they overwinter as larvae on the host plants (Borkin 2000a, p. 2), 
where they are exposed to fires during their larval stages. If larvae 
are on prairie dropseed or little bluestem, which occur in dry prairie, 
rather than spike-rush or sedges, which typically occur in wet prairie, 
then the larvae are even more vulnerable to fire (Selby 2005, p. 36). 
Unlike Dakota skippers, Poweshiek skipperlings do not burrow into the 
soil surface (McAlpine 1972, pp. 88-92; Borkin 1995b, p. 9), which 
makes them more vulnerable to fire (and likely more vulnerable to 
chemicals such as herbicides and pesticides)) throughout their larval 
stages. Species whose larvae spend more time above ground, such as 
Poweshiek skipperlings, are likely more vulnerable to fire than species 
that form underground shelters. As the spring progresses, however, the 
vulnerability of Dakota skippers to fire increase as larvae shift from 
buried shelters to horizontal shelters at the soil surface (Dana 1991, 
p. 16).
    Studies of all life-stages may be necessary to fully evaluate these 
species' response to fire. Early spring burns may be less likely to 
harm Dakota skipper populations than late spring burns, due to larval 
phenology and differences in subsurface soil temperatures during the 
fire; however, studies have not conclusively linked the relationship of 
mortality risk to the timing of spring burns. Experiments to evaluate 
the effects of early spring versus late spring fires and of different 
fuel levels on Dakota skipper mortality found that, despite higher 
ambient temperatures during the early spring burn, temperatures at the 
average depth of buried Dakota skipper shelters (Dana 1991, p. 11), 
were 10 [deg]C (50 [deg]F) higher during the late-spring burn (Dana 
1991, p. 41). Fuel load was positively related to subsurface soil 
temperature (Dana 1991, pp. 41-43). Fuel loads that were clearly 
associated with lethal subsoil temperatures, however, were more typical 
of mesic tallgrass prairie, which had about twice the fuel loads of the 
dry-mesic habitats inhabited by Dakota skippers on the site (Dana 1991, 
pp. 41, 54). Although Dana's study was inconclusive in quantifying the 
risk of mortality in relation to the timing of spring burns, he was 
able to conclude that a late-spring burn in ``moderate'' fuels (430-440 
g/m\2\) would have a devastating effect on Dakota skipper populations, 
and that early spring burning would afford some amelioration (Dana 
1991, p. 55).
    Rotational burning may benefit prairie butterflies by increasing 
nectar plant density and by positively affecting soil temperature and 
near-surface humidity levels due to reductions in litter (Dana 1991, 
pp. 53-55; Murphy et al. 2005, p. 208; Dana 2008, p. 20). Purple 
coneflower and little bluestem, for example, occurred more frequently 
on burned areas than on unburned areas in mixed-grass prairie at 
Lostwood National Wildlife Refuge in northwestern North Dakota (Murphy 
et al. 2005, pp. 208-209). An increase in purple coneflower, an 
important nectar source for Dakota skippers and Poweshiek skipperlings, 
may last for 1-2 years after early spring fires and females may 
preferentially oviposit near concentrations of this nectar source (Dana 
2008, p. 20).
    Although fire tends to increase native plant diversity in prairies 
(Murphy et al. 2005, pp. 208-209), several years may be necessary for 
Dakota skipper and Poweshiek skipperling populations to recover after a 
burn. Few studies have documented recovery times for prairie 
butterflies after a burn, and even fewer have measured the 
relationships between species abundance in tallgrass prairies and time 
since burn. One such study, however, found lower relative abundances of 
Dakota skippers and Poweshiek skipperlings in burned units than in 
otherwise similar hayed units even four years after burns (Swengel 
1996, p. 83). Poweshiek skipperling had the most negative initial 
response to fire among six species of prairie-obligate butterfly 
species (Swengel 1996, p. 83). Numbers were still lower than expected 
one year post-fire, exceeded expectations after two years, and declined 
slightly after three years (Swengel 1996, p. 83). In habitats that had 
not been burned for four or more years, Poweshiek skipperling abundance 
was about as low as in habitats sampled less than one year after being 
burned (Swengel 1996, p. 83).
    Swengel's (1996, p. 83) observations are consistent with other 
findings. That is, Poweshiek skipperling numbers decline in burned 
areas for 1-2 years after the burn then rebound, but may decline again 
if management does not maintain the habitat (Skadsen 2001, p. 37; 
Webster 2003, p. 12). In general, recovery times of 1-5 years post burn 
have been predicted (Swengel 1996, pp. 73, 79, 81; Panzer 2002, pp. 
1302-1303); however, Vogel et. al (2010, p. 671) found that habitat-
specialist butterfly abundance recovery time was approximately 50 
months after prescribed fires. Recent survey results in some areas, 
most notably, Iowa and Minnesota, indicate that other factors are 
acting independently (Dana 2008, p. 18) or in concert with fire to 
forestall the typical post-fire rebound.
    We assessed the stressor posed by fire at 19 Dakota skipper sites 
with present or unknown status and 24 Poweshiek skipperling sites with 
present or unknown site status where we had sufficient information to 
evaluate the stressor (Tables 3 and 4; Service 2012 unpubl. data; 
Service 2013, unpubl. data). We considered fire a stressor of high 
level of impact to populations at 9 of the 19 evaluated Dakota skipper 
sites and 7 of the 24 Poweshiek skipperling sites. Sites that face a 
high level of impact to populations were primarily those with a high 
proportion of Dakota skipper or Poweshiek skipperling habitat that may 
be burned in a single year or where all of the species' habitat is 
burned with no likely source of immigrants to sustain the population. 
This type of fire management is a documented cause of extirpation 
(Selby 2000, p. 19). Sites with a moderate level of impact to 
populations from fire management were those where the habitat is 
divided into at least three burn units and no unit is burned more 
frequently than once every three years; or, habitat is divided into two 
or more burn units, each unit is burned no more frequently than once 
every three years, but the entirety of the species' habitat is never 
burned in the same year and the species is present at another site that 
is less than 1 km (1.6 mi) away. Fire is considered to be a threat of 
moderate severity at 4 of the 19 evaluated Dakota skipper sites and 3 
of the 24 Poweshiek skipperling sites. Fire presents a low level of 
impact to populations at sites where the species' habitat is divided 
into at least four burn units and no unit is burned more frequently 
than once every four years; or, the species' habitat is divided into 
three or more burn units, at least three units are burned no more 
frequently than once every four years, and the site contains more than 
140 ha (346 ac) of native prairie or where the site is separated from 
another occupied site by less than 1 km (1.6 mi). Fire is considered to 
be a stressor with a low level of impact to populations at 6 of the 19 
evaluated Dakota skipper sites and 14 of the 24 Poweshiek skipperling 
sites.
    In summary, fire may be an important management tool for these 
butterflies, if carried out appropriately. However, where managers burn 
without ensuring a sufficient amount of contiguous or nearby habitat 
from which immigrants can re-inhabit burned areas or if not

[[Page 63602]]

conducted with conservation of prairie invertebrates as a primary 
objective, it is a current stressor that can have moderate impacts on 
populations. Uncontrolled wildfires may also have high or moderate 
levels of impacts to populations, and would also depend on the timing, 
intensity, and extent of the burn. Poweshiek skipperlings may be among 
the most sensitive of prairie butterflies to fire, and thus, 
coordination between habitat managers and butterfly experts is 
necessary to ensure that it is not implemented in a manner that 
degrades population viability. Fire is a current and ongoing stressor 
of high level of impact where burns occur without ensuring there is a 
sufficient amount of contiguous or nearby habitat from which immigrants 
can re-inhabit burned areas. Fire is an ongoing stressor rangewide for 
both species and has been documented at a high or moderate level of 
impact to populations at several sites in North Dakota, South Dakota, 
Minnesota, Wisconsin, and the Tallgrass Prairie Preserve in Manitoba.
Grazing
    As with fire management, grazing may maintain habitat for the 
Poweshiek skipperling and Dakota skipper, but as with any management 
practice, appropriate timing, frequency, and intensity are important. 
The level of impact of grazing on Dakota skipper and Poweshiek 
skipperling populations also depends on the type of habitat that is 
being grazed. Furthermore, in contrast to the permanent habitat 
destruction and larval mortality caused by plowing or mining, for 
example, some habitats can remain suitable for Dakota skipper when 
grazed (Dana 1991, p. 54, Schlicht 1997, p. 5, Skadsen 1997, pp. 24-29) 
and native plant diversity in tallgrass prairie may recover from 
overgrazing if it has not been too severe or prolonged. In addition, 
grazing is one of the primary treatments for controlling smooth brome 
and enhancing native plant diversity in prairies that have been invaded 
by this nonnative grass species (Service 2006, p. 2; Smart et al. in 
prep.).
    Grazing may benefit the Dakota skipper and Poweshiek skipperling 
under some management scenarios (e.g., adaptive management to adjust 
grazing prescriptions according to their effects on essential features 
of the prairie ecosystem). In some habitats, Dakota skippers benefit 
from light grazing that minimizes the area dominated by tall grasses 
(e.g., big bluestem and indiangrass) (Dana 1991, p. 54). Schlicht 
(1997b, p. 5) found that the Dakota skipper was relatively abundant on 
prairies subjected to light grazing regimes, but absent on nearby idle 
prairies that were no longer used for grazing; moreover, he observed 
more Dakota skippers per hour on the lightly grazed prairies than on 
nearby habitat managed with fire (Schlicht 1997b, p. 5). Similarly, in 
eastern South Dakota, Dakota skipper populations were deemed secure at 
some sites managed with rotational grazing light enough to maintain 
plant species diversity (Skadsen 1997, pp. 24-29), but the species was 
since extirpated at one site where a change in ownership resulted in 
significant overgrazing (Skadsen 2006b, p. 5). The economic benefit of 
grazing to ranchers may also benefit the species at some sites by 
deterring conversion of remnant prairies to row crop agriculture.
    Bison (Bison bison) grazed at least some Dakota skipper and 
Poweshiek skipperling habitats historically (McCabe 1981, p. 190; Bragg 
1995, p. 68; Schlicht and Orwig 1998, pp. 4, 8; Trager et al. 2004, pp. 
237-238), but cattle (Bos taurus) are now the principal grazing 
ungulate in both species' ranges. Bison and cattle both feed primarily 
on grass, but have some dissimilar effects on prairie habitats 
(Damhoureyeh and Hartnett 1997, pp. 1721-1725; Matlack et al. 2001, pp. 
366-367). Cattle consume proportionally more grass and grasslike plants 
than bison, whereas bison consume more browse and forbs (flowering 
herbaceous plants) (Damhoureyeh and Hartnett 1997, p. 1719). Grasslands 
grazed by bison may also have greater plant species richness and 
spatial heterogeneity than those grazed by cattle (Towne et al. 2005, 
pp. 1553-1555). Both species remove forage for larvae (palatable grass 
tissue) and adults (nectar-bearing plant parts), change vegetation 
structure, trample larvae, and alter larval microhabitats. Livestock 
grazing was identified as a stressor to populations on most of the 
privately owned sites and some public sites on which Dakota skippers 
occurred in 2002 (Cochrane and Delphey 2002, pp. 62-69). Swengel and 
Swengel (1999, p. 286), for example, noted that at the Sheyenne 
National Grassland in North Dakota, grazing appeared to be unfavorable 
for the Poweshiek skipperling and Dakota skipper.
    Reduced availability of nectar resources and larval food plants is 
likely the primary factor leading to declines in Poweshiek skipperling 
and Dakota skipper populations on heavily grazed sites. In South 
Dakota, for example, Higgins (1999, p. 15) found lower plant diversity 
on privately owned prairies, which were mostly grazed, than on publicly 
owned prairies, which were almost all idle (no grazing or fire 
management). McCabe (1981, p. 189) observed that grazing eliminated 
Dakota skippers on North Dakota wet-mesic prairies; nectar plants such 
as yellow sundrops and bluebell bellflower rapidly diminished with 
light grazing, and heavy grazing eliminated upright prairie coneflower 
and purple coneflower.
    The intensity at which grazing occurs may dictate the level of 
impact to the Dakota skipper and Poweshiek skipperling. Grazing reduces 
Dakota skipper numbers in direct proportion to its intensity, due to 
the reduction in flowers that provide nectar and perhaps by influencing 
adult behavior (Dana 1997, p. 4). Dana (1997, p. 5) predicted that 
privately owned pastures in Minnesota's Hole-in-the-Mountain complex, 
for example, will likely only support low densities of skippers if they 
continued to be heavily grazed and sprayed with herbicides. Surveys at 
this habitat complex in 2007, 2008, and 2012 failed to record any 
Poweshiek skipperlings (Dana 2008, p. 8; Selby 2009a, pp. xxxi-xxxii; 
Runquist 2012a, pers. comm.; Runquist 2012, pp. 13-14, 18-20) and 
Dakota skippers were not detected in 2012 surveys (Runquist 2012, pp. 
13-14, 18-20; Runquist 2012a, pers. comm.).
    While most references to grazing impacts on prairie butterflies are 
based on ancillary observations made during research focused on other 
management impacts, one Minnesota study (Selby 2006b) focused on the 
effects of grazing on all life stages of the Dakota skipper, and also 
included data for the adult stage of the Poweshiek skipperling. Both 
species were too scarce to collect data adequate to test the hypotheses 
(Selby 2006b, p. 2), but observations based on two years (2003 and 
2004) of surveys suggested that numbers in the lightly to moderately 
grazed pasture were similar to those in the best portions of nearby 
ungrazed habitats (Selby 2006b, p. 30). Poweshiek skipperlings were 
almost absent from the study sites (Selby 2006b, pp. iii-xxiii). Within 
the grazed study area, the number of Dakota skippers declined with 
increasing grazing intensity; Dakota skippers were absent from the most 
heavily grazed areas (Selby 2006b, p. 16). Skadsen (2001, p. 55) found 
that forb diversity was poor on the grazed lands and predicted the 
extirpation of both species unless management practices were changed. 
The Dakota skipper is now extirpated at one of these sites, and its 
status is unknown at the other; Poweshiek skipperling status is unknown 
at both sites (Service 2013, unpubl. geodatabase). Spomer (2004, p. 4) 
found that larval host plants and

[[Page 63603]]

nectar sources were missing from heavily grazed pastures at Sheyenne 
National Grassland, North Dakota.
    Grazing intensity combined with varying habitat type may also 
affect the level of grazing impacts. On wet-mesic habitat in North 
Dakota, for example, Dakota skippers and Poweshiek skipperlings 
tolerate little to no grazing (McCabe and Post 1977b, p. 36; Royer and 
Marrone 1992a, pp. 10, 17, 28; Royer and Marrone 1992b, pp. 17-18; 
Royer and Royer 1998, p. 22). Webster (2003, pp. 7-8) described very 
similar Dakota skipper habitats in Manitoba and, although grazing 
generally does not occur in these habitats that are occupied by Dakota 
skipper, they may be as sensitive to grazing as similar habitats in 
North Dakota; in a later report, he described the conversion of lands 
from haying to grazing as a major threat to Dakota skipper in the wet-
mesic habitats of Manitoba (Webster 2007, pp. i-ii, 6). In the drier 
and hillier habitats that the species inhabits, grazing may benefit 
Dakota skipper depending on its intensity. For example, in eastern 
South Dakota, Dakota skipper populations were deemed secure at some 
sites managed with rotational grazing that was sufficiently light to 
maintain native plant species diversity (Skadsen 1997, pp. 24-29), and 
grazing may also benefit Dakota skippers by reducing the area dominated 
by tall native grasses, such as big bluestem and Indiangrass (Dana 
1991).
    Proximity of nearby populations or contiguous habitat may alleviate 
some of the negative impacts of grazing. Royer and Marrone (1992b, p. 
29; 1992a, p. 18) stated that heavy grazing was a threat to Dakota 
skippers and Poweshiek skipperlings, but that occasional light grazing 
is not a long-term threat in some habitats as long as there are areas 
of contiguous habitat that remain ungrazed. At Chekapa Creek Ridge and 
Knapp Pasture in South Dakota, heavy grazing apparently extirpated both 
the Poweshiek skipperling and Dakota skipper (Skadsen 2002, p. 38; 
2004, p. 7; 2006a, p. 11). Due to its proximity to other Poweshiek 
skipperling populations and a return to fall haying in 2005, the 
Poweshiek skipperling recolonized Chekapa Creek Ridge in 2006 (Skadsen 
2006a, p. 12), but more recent surveys indicate that the Poweshiek 
skipperling has again been extirpated from this site due to habitat 
degradation because of a change from haying to grazing (Skadsen 2012a, 
pers. comm., Skadsen 2012c, pers. comm.).
    As with fire, Dakota skipper and Poweshiek skipperling populations 
may persist through intense grazing episodes or be restored afterwards, 
if sufficient numbers survive and reproduce in lightly grazed patches 
or if nearby habitats provide sufficient numbers of immigrants to 
reestablish the population after habitat quality is restored. Years of 
grazing without rest, however, may preclude recovery from the effects 
of intense grazing, although the capacity for restoration of suitable 
plant community and other habitat features may be highly variable among 
sites. On some sites, plant diversity may not be restored when grazing 
pressure declines (Dana 1997, p. 30; Jackson 1999, pp. 134-135; Spomer 
2004, p. 4). Grazing intensely (where a high proportion of plant 
biomass is removed) or for long duration leads to native plants being 
replaced with exotic, cool-season European forage grasses and legumes 
that are tolerant of continuous grazing (Jackson 1999, p. 128, 
Minnesota DNR 2006, p. 232). In overgrazed native prairie in Minnesota, 
for example, the prairie is dominated by exotic grasses with a low 
native forb species diversity and abundance, and foliage height is less 
than 10 cm (4 in) (Dana 1997, p. 3); these prairies lack the native 
plants necessary to sustain adult and larval prairie butterflies. In 
comparison, sites less disturbed by grazing have a high native forb 
(nectar) species diversity and abundance foliage height is generally 
more conducive to perching and reproductive activities (between 25 and 
40 cm (10 and 16 in)) (Dana 1997, p. 2).
    Land managers also frequently use herbicides, often through 
broadcast application, to control weeds and brush on grazed remnant 
prairies, which further reduces native forb diversity and abundance 
(Dana 1997, p. 3; Stark et al. 2012, pp. 25, 27) necessary for adult 
nectar sources. Skadsen (2006, p. 11), for example, documented the 
likely extirpation of Dakota skippers at Knapp Ranch in South Dakota 
after a July 2006 application of broadleaf herbicide in concert with 
heavy grazing. Herbicide and pesticide use is discussed further under 
Factor E of this proposed rule.
    While reduced availability of nectar resources and larval food 
plants may be the primary factors leading to declines in Poweshiek 
skipperling and Dakota skipper populations on heavily grazed sites, 
changes in vegetation structure may also be important. For example, 
grazing prairie each year during mid-summer eliminates nectar plants, 
such as purple coneflower, and native warm-season grasses that function 
as larval host plants (Skadsen 2007, pers. comm.). In South Dakota, 
vegetation height and litter depth were lower on prairie remnants that 
were mostly grazed (Higgins 1999, pp. 27-29). Grazing also causes 
direct mortality of larvae due to trampling and altering larval 
microhabitats (Royer et al. 2008, pp. 10-15). In North Dakota, grazing 
can compact soils in wet-mesic prairie inhabited by Dakota skippers and 
Poweshiek skipperlings, altering vertical water movement in the soil, 
which may lead to larval desiccation (Royer et al. 2008, p. 16). Cattle 
may also kill larvae by trampling them, particularly in wet-mesic 
prairies (McCabe 1981, p. 189).
    Livestock grazing is the predominant use of privately owned 
tallgrass prairie remnants in South Dakota (Higgins 1999, p. 15) and 
was identified by the Service as a threat on most of the privately 
owned sites on which Dakota skipper occurred when the species was 
identified as a candidate species in 2002 (Cochrane and Delphey 2002, 
pp. 62-69). The presence and density of purple coneflower may serve as 
an indicator of grazing impacts to Dakota skippers and Poweshiek 
skipperlings where the species occur in dry-mesic prairie (Skadsen 
2006a, p. 2); grazing from mid-June through July may reduce purple 
coneflower abundance (Skadsen 2007, pers. comm.)--as discussed in the 
Background section of this rule, purple coneflower has been identified 
as a primary source of nectar for both species, particularly in dry 
prairie habitats.
    Britten and Glasford (2002, p. 373) recommended minimizing 
disturbance of Dakota skipper habitat during the flight period (late 
June to early July) to maximize genetically effective population sizes 
(the number of adults reproducing) to offset the effects of genetic 
drift of small populations (change in gene frequency over time due to 
random sampling or chance, rather than natural selection). Therefore, a 
large portion of the habitat of any Dakota skipper population should 
remain ungrazed or only lightly grazed during the flight period, and 
similar precautions should be taken for the Poweshiek skipperling.
    We assessed the level of impact to populations from grazing at 53 
Dakota skipper sites and 23 sites currently occupied by Poweshiek 
skipperling with present or unknown status that had sufficient 
information to evaluate the stressor (Tables 3 and 4; Service 2012 
unpubl. data; Service 2013, unpubl. data). This analysis was conducted 
differently for different habitat types. For Type A habitat (Royer et 
al. 2008, pp. 14-16) where stocking rates (number of cattle or bison 
over a given area) have little or no evidence of grazing effects on 
Dakota skipper or Poweshiek skipper habitat quality, we found the level 
of impact to populations of grazing to be low. For Type B habitat

[[Page 63604]]

(Royer et al. 2008, p. 14), we assumed that the level of impact of 
grazing to populations would be low if the dry-mesic slopes were grazed 
only before June 1 with at least one year of rest between rotations and 
if the pasture were only spot-sprayed with herbicides when and where 
necessary, or, the best available information does not indicate that 
grazing practices are degrading habitat quality for the species (i.e., 
no apparent diminishment of nectar plant density and diversity and 
habitat is good or excellent for Dakota skipper).
    At grazed sites where extirpation of the local population is not 
imminent, but habitat quality is fair to poor and the relative 
abundance of Dakota skippers or Poweshiek skipperlings is often low, we 
found the level of impact of grazing to populations to be moderate. 
Sites with a moderate level of impact to populations due to grazing may 
be lightly grazed for less than 4 months or less than 25 percent of the 
above-ground biomass of native grasses and forbs is consumed (Smart et 
al. 2011, pp. 182-183), are grazed after June 1, or are not given a 
year of rest between grazed years. At sites where grazing is conducted 
season-long, or for more than four months during the year, or more than 
50 percent of the above-ground biomass of native grasses and forbs is 
consumed and herbicide use is frequent; we found the level of impact of 
grazing to populations to be high. At sites where grazing is a high-
level threat, extirpation of the population is likely imminent and 
habitat quality is poor. On public lands inhabited by the species, 
grazing is typically used to control nonnative cool-season grasses and 
invasive species. Cattle are often removed by July 1 to minimize 
adverse impacts to warm-season grasses, but this type of management 
minimizes the density of nectar species that are important to the 
Dakota skipper and Poweshiek skipperling. Invasive species are often 
present at grazed sites, which often lead to further management actions 
(see Invasive Species and Secondary Succession).
    Of the 53 Dakota skipper sites assessed, we found the level of 
impact to Dakota skipper populations from grazing to be high at 10 
sites, moderate at 29 sites, and low at 14 sites (Service 2012 unpubl. 
data; Service 2013, unpubl. data). Moderate- to high-level impacts to 
populations were primarily at South Dakota sites (N=28)--other sites 
with moderate- to high-level impacts were in Minnesota (N=7), North 
Dakota (N=3), and Manitoba (N=1). As described above as part of our 
assessment of grazing, we examined the habitat quality ratings that 
were primarily assigned by researchers during surveys for the species, 
during separate habitat assessments, or that were available from state 
heritage databases or other sources of scientific data. The habitat 
quality was rated as poor at 7 of the 10 sites where grazing poses a 
high level of impact to Dakota skipper populations. At each of the 14 
sites where grazing pressure is low, habitat quality was good or 
excellent, with two exceptions where habitat was rated as fair to good. 
Among the 29 sites where grazing is a moderate level of impact to 
Dakota skipper populations, 6 had habitat rated good or excellent.
    Of the 19 Poweshiek skipperling sites for which we had sufficient 
information to assess grazing, the level of impact to populations from 
grazing is high at 7 sites, moderate at 14 sites, and low at 2 sites--
all but 2 of these sites were in South Dakota. No sites in Wisconsin or 
Michigan were assessed for grazing impacts to populations, where the 
grazing does not occur. Among the 14 sites where grazing is a moderate 
level of impact to Poweshiek skipperling populations, 10 have habitat 
rated as fair to excellent. The habitat quality was rated as poor at 3 
of the 6 sites where grazing is having a high level of impact to 
Poweshiek skipperling populations.
    In summary, grazing may benefit Dakota skippers and Poweshiek 
skipperlings in native tallgrass prairie by increasing native plant 
diversity and patchiness of fires (Minnesota DNR 2006, p. 232). The 
economic benefit of grazing to ranchers may also be a benefit to the 
species by deterring conversion of remnant prairies to row crop 
agriculture. Grazing is a stressor to these species, however, if it is 
not managed with the goal of conserving native-prairie vegetation that 
comprises suitable habitat for Dakota skipper and Poweshiek 
skipperling. Dakota skippers and Poweshiek skipperlings may benefit 
when prairie habitat is rested from grazing for at least a part of each 
growing season, if livestock are precluded from removing too much plant 
material (e.g., are moved when stubble heights are 6-8 in (15-20 cm) 
(Skadsen 2007, pers. comm.), and if the timing of grazing for each 
field varies from year to year (Skadsen 2007, pers. comm.).
    Conversely, Dakota skipper and Poweshiek skipperling populations 
may be reduced or extirpated when too much plant material is removed, 
when fields are not rested for some portion of the growing season, or 
fields are grazed during the same period each year. Grazing poses a 
current and ongoing stressor of moderate to high level of impact to 
populations where its intensity is such that Dakota skippers and 
Poweshiek skipperlings are unlikely to thrive or even persist. Grazing 
poses a likely future stressor where current management is conducive to 
Dakota skipper or Poweshiek skipperling conservation, but where 
landowners may allow excessive grazing in the future, for example, 
where management may change as a result of the changing market prices 
of agricultural products. Unsuitable grazing is an ongoing stressor 
throughout much of the range of the Dakota skipper and Poweshiek 
skipperling (primarily in flat wet prairies of Minnesota, North Dakota, 
and South Dakota); grazing is not a documented stressor at the 
Poweshiek skipperling sites with present or unknown status in 
Wisconsin, Michigan, and Iowa or at most Dakota skipper sites in 
Canada.
Haying
    As with grazing and fire, haying (mowing grasslands and removing 
the cuttings) may maintain habitat for the Poweshiek skipperling and 
Dakota skipper, but as with any management practice, appropriate 
timing, frequency, and intensity are important. Poweshiek skipperling 
habitat at Scuppernong Prairie in Wisconsin, for example, would have 
succeeded to shrubby or forested habitat if it had not been hayed each 
fall (Borkin 2011, in litt.)--it is now one of the few sites in 
Wisconsin that are occupied by the Poweshiek skipperling. Nearly all of 
the Dakota skipper sites in Canada where the species is present are 
privately owned, fall hayed prairies (Westwood 2013, pers. comm.).
    Haying generally maintains prairie vegetation structure, but it may 
favor expansion of invasive species such as Kentucky bluegrass. If done 
during the adult flight period, haying may kill the adult butterflies 
or cause them to emigrate, and if done before or during the adult 
flight period, it may reduce nectar availability (McCabe 1979, pp. 19-
20; McCabe 1981, p. 190; Dana 1983, p. 33; Royer and Marrone 1992a, p. 
28; Royer and Marrone 1992b. p. 14; Swengel 1996, p. 79; Webster 2003, 
p. 10). Royer and Marrone (1992b, p. 14), for example, ascribed the 
loss of a North Dakota Poweshiek skipperling population to June and 
July haying. Several years of July haying may have led to the Poweshiek 
skipperling's extirpation at Wakidmanwin Prairie in South Dakota 
(Skadsen 2006b, p. 13). The Dakota skipper was observed at the 
Wakidmanwin Prairie in 2010 (Skadsen 2010, p. 6); however, it is not 
clear if the management has changed since the observation. Early June 
haying may have

[[Page 63605]]

eliminated Dakota skippers from at least one site in North Dakota 
(Royer and Royer 2012a, p. 72).
    Hayed prairies are important reservoirs of native prairie plant 
diversity; however, long-term annual haying negatively impacts prairie 
plant diversity (Jog et al. 2006, pp. 164-165). Jog et al. (2006, pp. 
164-165) recommended diversifying management to include, for example, 
periodic fire and to forego annual haying to increase plant species 
diversity. In a long-term study of a prairie in southeastern Wisconsin, 
a switch from late-season haying to fire management led to increased 
native plant diversity and coverage of warm-season grasses, although 
woody plant species also increased (Rooney and Leach 2010, p, 319).
    Late-season haying may benefit Dakota skipper populations (McCabe 
1981, p. 190), and Dakota skipper populations might be more common on 
hayed prairies than on idle (not hayed) prairies (Webster 2003, p. 10). 
Swengel and Swengel (1999, p. 279) observed significantly greater 
relative abundance of Dakota skippers on hayed tracts compared with 
either idle or burned tracts in Minnesota, and Skadsen (2004, p. 7) 
documented the extirpation of Dakota skippers from a site after its 
management switched from haying to intensive grazing. Some remnant 
Dakota skipper populations in the eastern Dakotas are found on fall-
hayed prairies (Skadsen 1997, pp. 10-23; Royer and Royer 2012b) as are 
many of the sites in Manitoba (Webster 2003, p. 10). Webster (2003, p. 
8) found ``healthy populations'' of Dakota skippers in Manitoba on 
sites used as hay fields, as described by the absence of standing dead 
grass, low numbers of shrubs, shorter bluestem grasses, and abundant 
and readily observable nectar flowers, as compared to un-hayed sites. 
Scarlet Fawn Prairie in South Dakota, which is hayed in the fall, is 
considered one of the highest quality prairies in that State (Skadsen 
2012, pers. comm.). In the Dakotas, late-season (mid-August to October) 
haying appears to minimize impacts to the prairie butterflies, although 
annual haying may diminish the vigor of native, warm-season grasses and 
reduce forb density in north-central North Dakota (wet-mesic) habitats 
(Lenz 1999b, p. 14; Skadsen 2009, p. 8). Consistent late-season haying 
of Poweshiek skipperling habitat in South Dakota, appears to have 
facilitated the expansion of green needlegrass (Stipa viridula), a 
cool-season grass, and prevented seed development in warm-season plants 
(Skadsen 2009, p. 8).
    We assessed the level of impact of haying to populations at 40 
Dakota skipper sites and 10 Poweshiek skipperling sites with present or 
unknown status where we had sufficient information to assess the 
stressor (Tables 3 and 4; Service 2012 unpubl. data; Service 2013, 
unpubl. data). Haying was considered to be a stressor with a low or no 
negative impact on populations where it is implemented after the flight 
period (after approximately August 1) and when there is no reduction in 
the availability of native plant species. Haying was considered to be a 
stressor with a moderate level of impact on populations, where the 
timing or extent of haying was unknown, but there are: (1) One or more 
indications that haying is resulting in a reduction in nectar or larval 
food sources important to the species due to timing or frequency of 
mowing; (2) part of the Dakota skipper or Poweshiek skipperling habitat 
on the site is hayed before August 1, but a substantial proportion of 
habitat is not hayed and not clearly subject to other threats, such as 
frequent fire or grazing (e.g., Smokey Lake site, North Dakota); or (3) 
where haying occurs before or after August 1, but the site is hayed no 
more frequently than once every three years (e.g., Roy West Game 
Production Area, South Dakota).
    We considered haying to be a stressor with a high level of impact 
on populations where the site was hayed prior to August 1 (e.g., Oaks 
Prairie, North Dakota). At 27 of the 40 evaluated Dakota skipper sites, 
current haying practices are conducive (beneficial) to Dakota skipper 
conservation, because it is conducted after August 1 and is not 
reducing native plant species diversity. One or more indications that 
current haying practices are slowly degrading habitat quality for 
Dakota skippers has been documented at 13 of the 40 sites. At several 
sites in North Dakota, for example, Royer and Royer (2012b, pp. 15, 21, 
24, 45) noted a decrease in the diversity and density of forbs at sites 
hayed annually. Haying is a stressor with a high level of impact on 
populations at 2 of the 40 Dakota skipper sites assessed and a stressor 
of moderate-level impacts to the populations at 11 of the 40 Dakota 
skipper sites assessed. Of the 10 Poweshiek skipperling sites 
evaluated, haying was a stressor with moderate-level impacts on 
populations at 3 sites and was not considered to have high-level 
impacts to the populations at any of the 10 sites.
    In summary, haying is a current and ongoing threat of moderate to 
high level of impacts to Dakota skippers and Poweshiek skipperlings at 
the few sites where the site is normally hayed before August and where 
annual haying is reducing availability of larval food and adult nectar 
plants. However, fall haying is beneficial to both species, 
specifically if it is conducted after August 1, no more than every 
other year, and there is no indication that native plant species 
diversity is declining due to timing or frequency of haying. Haying is 
a current stressor at a small number of sites for both species; these 
sites occur primarily in North Dakota and South Dakota.
Lack of Disturbance
    While inappropriate or excessive grazing, haying, and burning are 
stressors to some Poweshiek skipperling and Dakota skipper populations 
and have led to the extirpation of others, both species are also 
subject to the stress of no management practices being implemented. 
Prairies that lack periodic disturbance become unsuitable for Poweshiek 
skipperlings and Dakota skippers due to expansion of woody plant 
species (secondary succession), litter accumulation, reduced densities 
of adult nectar and larval food plants, or invasion by nonnative plant 
species (e.g., smooth brome) (McCabe 1981, p. 191; Dana 1983, p. 33; 
Dana 1997, p. 5; Higgins et al. 2000, p. 21; Skadsen 2003, p. 52). For 
example, Dakota skipper numbers were reduced at Felton Prairie, 
Minnesota, in tracts that had not been hayed or burned for several 
years (Braker 1985, p. 47). Another study also observed significantly 
lower Dakota skipper abundance on unmanaged or idle sites, compared 
with hayed sites; however, Poweshiek skipperlings were significantly 
denser with idling (Swengel and Swengel 1999, p. 285). Skadsen (1997, 
pp. 10-23; 2003, pp. 8, 35, 42) reported deterioration of several 
unburned and unhayed South Dakota prairies in just a few years due to 
encroachment of woody plants and invasive species and found lower 
species richness of prairie-dependent butterflies and lower floristic 
quality at sites with no disturbance versus sites managed by grazing or 
fall haying (Skadsen 2006a, p. 3). For example, Dakota skippers 
returned to an idle site, Pickerel Lake State Park, after a burn 
conducted in 2007 resulted in a significant increase in forbs, 
particularly purple coneflower (Skadsen 2008, p. 2). In a separate 
study, Higgins et al. (2000, p. 24) found that prairie habitats left 
idle had lower plant diversity and quality than prairies managed with 
fire.
    We assessed the stressor posed by lack of management for 
populations at 18 Dakota skipper sites and 13

[[Page 63606]]

Poweshiek skipperling sites with present or unknown status where we had 
sufficient information to evaluate the stressor (Tables 3 and 4; 
Service 2012 unpubl. data; Service 2013, unpubl. data). Lack of 
management was considered to be a stressor of moderate-level impacts to 
the population where the species' habitat is degraded or likely to 
become degraded due to secondary succession, invasive species, or both, 
but actions to restore habitat quality are planned or ongoing, or where 
the site is idle with no evident plans to initiate management (e.g., 
fire, grazing, haying), and there are signs of ongoing or imminent 
secondary succession. Lack of management was considered to be a 
stressor with a high level of impact to the population where the 
habitat quality at a site is degraded or likely to become degraded due 
to secondary succession or invasive species, and there are no ongoing 
or planned actions to maintain or restore habitat quality. Lack of 
management was considered to be a stressor of low-level impacts to 
Dakota skipper or Poweshiek skipper populations at sites that are 
managed by grazing, haying/mowing, or fire that precludes loss of 
Dakota skipper or Poweshiek skipperling habitat to secondary succession 
and invasive species (e.g., smooth brome). Ten of the 18 Dakota skipper 
sites assessed are under high level of impact to population due to lack 
of management and 5 sites are under moderate level of impact to the 
population. Five of the 13 Poweshiek skipperling sites assessed are 
under high level of impact to the population due to lack of management 
and 6 sites are under moderate level of impact to the population. The 
Dakota skipper and Poweshiek skipperling are unlikely to persist at 
those sites where the level of impact to the population due to lack of 
management is high. Sites currently under stress by lack of management 
occur throughout the range of both species; however, most of the 
present or unknown sites that lack appropriate management are in North 
Dakota, South Dakota, Minnesota, and Michigan. In summary, lack of 
disturbance is a current and ongoing stressor to Dakota skipper and 
Poweshiek skipperling populations where woody vegetation or invasive 
species expansion will reduce native prairie grasses and flowering 
forbs.
Summary of Factor A
    We identified a number of threats to the habitat of the Dakota 
skipper and Poweshiek skipperling that operated in the past, are 
impacting both species now, and will continue to impact the species in 
the future. The decline of both species is the result of the long-
lasting effects of habitat loss, fragmentation, degradation, and 
modification from agriculture, development, invasive species, secondary 
succession, grazing, and haying. Although efforts have been made to 
effectively manage habitat in some areas, the long-term effects of 
large-scale and wide-ranging habitat modification, destruction, and 
curtailment will last into the future. Invasion of the species' habitat 
by exotic species and woody vegetation, overgrazing, long-lasting or 
permanent alterations in water levels or hydrology, and too frequent or 
improperly timed haying remove or significantly reduce the availability 
of plants that provide nectar for adults and food for larvae. Fire and 
flooding cause direct mortality or destroy nectar and food plants if 
the intensity, extent, or timing is not conducive to the species' 
biology.
    Of the 170 Dakota skipper sites for which we evaluated for one or 
more habitat stressors, at least 136 sites have at least one documented 
stressor with moderate to high levels of impact to populations--these 
sites are found across the current range of the species in Minnesota, 
North Dakota, South Dakota, Manitoba, and Saskatchewan (Service 2012 
unpubl. data; Service 2013, unpubl. data). Fifty-eight sites have 2 or 
more documented stressors of moderate to high levels of impact to 
populations, and 23 sites have three or more documented stressors of 
moderate to high level of impact to populations. Sites with three or 
more stressors are found across most of the current range of the 
species; these sites occur in Minnesota, North Dakota, South Dakota, 
and Manitoba (Service 2012 unpubl. data; Service 2013, unpubl. data). 
Twenty-three of these sites had 3 or more documented stressors at 
moderate or high levels of impact. Sites with three or more stressors 
are found across the current range of the species in the United States; 
these sites occur in Minnesota, North Dakota, and South Dakota. 
Furthermore, concurrently acting stressors may have more intense 
effects than any one stressor acting independently. Therefore, based on 
our analysis of the best available information, present and future loss 
and modification of Dakota skipper habitat is a stressor that has 
significant impacts on populations of the species throughout all of its 
range. Habitat-related stressors occur at sites with Dakota skipper 
populations within every state and province of occurrence.
    Similarly, of the 68 Poweshiek skipperling sites with present or 
unknown status that we analyzed for one or more habitat stressors, 55 
of them have at least one stressor at moderate to high levels of impact 
to the population. These sites are found across the current range of 
the species and occur in Iowa, Michigan, Minnesota, North Dakota, South 
Dakota, Wisconsin, and Manitoba (Service 2013, unpubl. data). Fifty-
five sites have 2 or more documented stressors that have moderate to 
high levels of impact to the population. These sites are found across 
the current range of the species and occur in Iowa, Michigan, 
Minnesota, North Dakota, South Dakota, Wisconsin, and Manitoba (Service 
2013, unpubl. data). Thirty-seven of them have at least three 
documented stressors that have moderate to high levels of impact to the 
population. These sites are found across the current range of the 
species and occur in Iowa, Michigan, Minnesota, North Dakota, South 
Dakota, Wisconsin, and Manitoba (Service 2013, unpubl. data). Thirty-
seven of these sites had 3 or more documented stressors at moderate or 
high levels of impact to the population for both species. These sites 
are found across most of the current range of the species and occur in 
Iowa, Michigan, Minnesota, North Dakota, South Dakota, and Manitoba 
(Service 2013, unpubl. data); furthermore, concurrently acting 
stressors may have more intense effects than any one stressor acting 
independently. Therefore, based on our analysis of the best available 
information, present and future loss and modification of Poweshiek 
habitat is a stressor that has significant impacts on the species 
throughout its range.
Conservation Efforts To Reduce Habitat Destruction, Modification, or 
Curtailment of Its Range
    In the past, funding for conservation of rare species was primarily 
directed toward federally listed or candidate species, so while the 
Poweshiek skipperling may have benefited indirectly from conservation 
activities focused on species such as the Dakota skipper and Mitchell's 
satyr (Neonympha mitchellii mitchellii), it has not generally been the 
primary focus of those activities. As a result, survey data and 
incidental life-history observations have been accumulated as a part of 
projects focused on other species, but surveys were not necessarily 
focused on Poweshiek skipperling sites and detailed life-history, 
population, and demographic data have generally not been collected for 
the species. Various conservation activities directed at the Dakota 
skipper also indirectly benefit the Poweshiek

[[Page 63607]]

skipperling; these activities are summarized below.
    Conservation agencies have recognized the need to address the 
status of prairie butterflies for more than 30 years beginning with a 
1980 workshop held to initiate studies of Dakota skippers and other 
prairie butterflies. In June 1995, the U.S. Fish and Wildlife Service 
convened Dakota skipper experts to outline tasks needed to preserve 
enough viable populations to ensure long-term security for the species. 
The group outlined a plan for surveying populations and characterizing 
sites and habitats at priority areas, identifying and recommending 
management needs, monitoring, and outreach and education. In 1999, a 
Dakota skipper recovery strategy meeting was held in South Dakota with 
state, Federal, and nongovernmental biologists attending (Skadsen 
1999b, entire). In 2011, researchers in Canada organized a Poweshiek 
Skipperling Workshop and followup conference call that brought together 
researchers and managers from across the range of the Poweshiek 
skipperling to provide updates on survey data, discuss ongoing 
activities, and plan future work. The workshop resulted in specific 
conservation action plans for the species. The Minnesota Zoo organized 
a followup conference during March 2013 to assess progress of the 2011 
Poweshiek Skipperling Workshop Action Plans, facilitate discussion on 
the potential effects of management activities on prairie butterflies, 
identify needed information and data gaps, establish new priorities for 
research and a draft action plan for 2013, and facilitate networking 
and collaborations focused on the conservation of the Dakota skipper 
and Poweshiek skipperling, as well as other tallgrass prairie 
butterflies in the Midwest.
    Research and survey work has occurred throughout the range of both 
species to document populations, to study the life history of both 
species, and to examine the effects of various management practices, 
such as fire and grazing, on the species and their habitat. For 
example, research and survey work on Dakota skippers began with Dana's 
(1991, entire) doctoral study on fire effects at Hole-in-the-Mountain, 
Minnesota, beginning in 1979 and McCabe's (1981, entire) 1979 surveys 
for the Garrison Diversion project in North Dakota. Additional work has 
been completed on characterizing habitat at important Dakota skipper 
sites in Minnesota (Dana 1997, entire) and North Dakota (Lenz 1999, 
entire, Royer and Royer 1998, entire, Royer and Royer 2012a, entire). 
Royer (2008, entire) assessed abiotic habitat parameters of soil in 
relation to management and conservation of Dakota skippers to 
complement prior floristic characterization of these habitats. The 
Minnesota DNR and the Service planned to cooperatively study the 
effects of grazing on the Dakota skipper and Poweshiek skipperling 
(Selby 2003a, entire; Selby 2003b, entire; Selby 2004b, entire, Selby 
2006, entire); however, skipper numbers were too low to collect 
sufficient data to test hypotheses (Selby 2006, p. 30).
    In the past, the Service funded some management activities intended 
to benefit the Dakota skipper, including habitat management at Big 
Stone National Wildlife Refuge, Minnesota (Olson 2000, entire), 
landowner contacts and education on conservation practices in South 
Dakota (Skadsen 1999b, entire), and prairie vegetation restoration at 
Chippewa Prairie in 2000 and at Twin Valley Prairie SNA, Minnesota, in 
2001. The results of these efforts are varied; for instance, the 
prairie habitat at Twin Valley Prairie SNA was recently rated as 
excellent quality (Service 2013, unpubl. geodatabase), but the status 
of both species at that site is unknown; the last positive observation 
of Dakota skippers and Poweshiek skipperlings was 1993 and 1994, 
respectively. The Dakota skipper is extirpated from Chippewa Prairie 
and the status of the Poweshiek skipperling is unknown at the site; the 
last positive observations of the species were in 1995 and 1994, 
respectively (Service 2013, unpubl. geodatabase).
    The Service purchases easements to prevent prairie conversion for 
agriculture and provide cost-share to support rotational grazing and 
other practices that may benefit Dakota skippers and Poweshiek 
skipperlings. For example, in 12 counties in South Dakota within the 
range of the species, the Service's grassland easement program has 
protected 365,193 ac (147,788 ha) of grassland that are primarily 
native prairie (Larson 2013, pers. comm.; HAPET 2012 unpubl. data), 
although it is not clear whether these lands are suitable habitat for 
either species. Other Service fee title lands, state lands, and Natural 
Resources Conservation Service easement lands may also protect areas 
from conversion, depending on the protections in those areas (Larson 
2013, pers. comm.). If easements are near prairie butterfly habitat 
they can minimize the threat of conversion and may provide dispersal 
corridors or buffer sites from external threats (e.g., pesticide 
drift).
    Prairie easements generally prevent grasslands from being plowed or 
destroyed and prevent haying before July 16, but may not restrict 
grazing, pesticide use, or other practices that can degrade the status 
of Dakota skipper or Poweshiek skipperling populations. For example, 
one property with a Service easement was recently overgrazed to the 
extent that Dakota skipper was extirpated from the site (Skadsen 2006b, 
p. 5). Cost-share partnerships on easements and other areas, however, 
may further enable landowners to manage grasslands to benefit Dakota 
skippers and other prairie endemic species. The Service may implement 
such actions through the Partners for Fish and Wildlife program or in 
collaboration with U.S. Department of Agriculture Natural Resources 
Conservation Service or other agencies. Since 1990, the Service has 
purchased easements to prevent grassland conversion on millions of 
acres in Minnesota, North Dakota, and South Dakota (Larson 2013, pers. 
comm.). Only some of these areas include Dakota skipper or Poweshiek 
skipperling sites, are within the range of either species, or include 
suitable habitat for either species.
    Conservation-interested agencies, individuals, and Tribes in South 
Dakota have made concerted efforts for decades to conserve native 
prairie within the Dakota skipper range. For example, there are 
approximately 54,000 ac (21,853 ha) of fee title lands in grassland 
that are managed by the Service in 12 of the counties within the 
historical or current range of the Dakota skipper and 365,000 ac 
(147,710 ha) protected by the Services' grassland easement program 
(Table 5; Larson 2013, pers. comm.). These acreages do not include an 
additional 4,000 ac (1,619 ha) of grass protected by acquisitions that 
have occurred in 2012 (Larson 2013, pers. comm.). Not all of these 
lands, however, may be managed in such a manner that is conducive to 
Dakota skipper populations.
    About one-half of the present or unknown Dakota skipper sites 
(total number of present/unknown sites is 172) in the United States are 
privately owned (excluding populations on land owned by The Nature 
Conservancy). Twelve of these populations are on private land on which 
the Service has purchased conservation easements that preclude plowing 
and haying before July 16. Manitoba Habitat Heritage Corporation has an 
easement that overlaps with one Dakota skipper site in Canada (Friesen 
2013, pers. comm.). Similarly, of the 70 privately owned sites where 
Poweshiek skipperling has

[[Page 63608]]

been recorded since 1985, 8 sites (all in Minnesota) have conservation 
easements. These easements do not prescribe grazing practices but are 
intended to prevent grassland conversion to cropland, which is 
detrimental to Dakota skippers or Poweshiek skipperlings. Additional 
measures on some easement properties could ensure grazing practices do 
not inadvertently impact either species.
    The Nature Conservancy's Minnesota and Dakotas offices initiated a 
Prairie Coteau Coordinated Conservation Planning Effort and Plan in 
1998 to facilitate conservation actions by various landowners, 
including private, county, state, tribal and Federal, on high 
biodiversity prairie sites (Skadsen 1999b, entire). Additional partners 
include conservation organizations, local conservation districts, and 
universities. The Nature Conservancy acquired a reserve in the Sheyenne 
Grassland area, Brown Ranch, which is a Dakota skipper site with an 
unknown status, and manages some of the most significant habitats for 
the two species in Minnesota, including the Hole-in-the-Mountain 
Prairie preserve. Based on intensive surveys in 2007, Dana (2008, p. 
19) found ``considerable reassurance'' that the rotational burning 
approach used at Prairie Coteau SNA and Hole-in-the-Mountain Preserve 
is compatible with long-term persistence of the Dakota skipper, for 
example, by controlling woody vegetation encroachment. The Minnesota 
DNR also manages the Prairie Coteau SNA with rotational burning (Dana 
2008, p. 19), which may control woody vegetation encroachment. The Clay 
County Stewardship Plan (Felton Prairie Stewardship Committee 2002) may 
have reduced the likelihood and severity of gravel mining within the 
Felton Prairie complex in Minnesota.
    Many of the best sites for Dakota skipper and Poweshiek skipperling 
in South Dakota are on tribal lands managed by the Sisseton-Wahpeton 
Sioux Tribe (e.g., Scarlet Fawn and Oak Island Prairies) (Skadsen 1997, 
Skadsen 2012, p. 3), with late season haying. According to Skadsen 
(2012, p. 3) ``. . . as in prior years, the fall hayed prairies held in 
trust by the Sisseton Wahpeton Oyate had the most diverse native flora 
and thus the largest numbers of Dakota skippers.'' Although these lands 
generally contain high-quality habitat for prairie butterflies in 
eastern South Dakota (Skadsen 2012, p. 3), a change to alternate year 
haying--instead of annual haying--may further improve habitat quality 
by ensuring that plants that flower during the Dakota skipper and 
Poweshiek skipperling flight periods are able to produce seed (Royer 
and Royer 2012, p. 15).
    The Day County Conservation District, South Dakota, places a high 
priority on implementing prescribed grazing on rangelands known to 
support Dakota skippers and bordering sites in the Upper Waubay Basin 
Watershed (Skadsen 1999b, p. 3). Their efforts include soliciting 
grants and providing education on grazing management, controlled 
burning, and integrated pest management to control leafy spurge, 
through workshops and a demonstration site. There are seven Poweshiek 
skipperling sites in Day County with unknown occupancy and no sites 
where the species is considered to be present. There are a total of 14 
Dakota skipper sites in Day County: 2 sites where the species is 
considered to be present, and 12 sites that have an unknown occupancy. 
It is not known how many of these sites are benefiting from these 
efforts and to what degree.
    In South Dakota, completed management plans guide habitat 
restoration at Hartford Beach State Park and Pickerel Lake State 
Recreation Area (Skadsen 2008, pp. 4-7; Skadsen 2011, pp. 1-4). At each 
site, the lack of haying, grazing, or fire had allowed plant succession 
to degrade and reduce the extent of Dakota skipper habitat. Dakota 
skipper habitat at these sites is divided into 3-4 management units. A 
controlled burn was conducted in one unit at Hartford Beach State Park 
in 2008, and shrubs were removed from two of the units (Skadsen 2008, 
p. 4). At Pickerel Lake State Recreation Area, a controlled burn was 
conducted in 2007, and in 2008 the site was hayed and shrubs were 
removed. The Dakota skipper was present in the burned unit for the 
first time since 2002 after ``a dramatic increase in forbs, especially 
purple coneflower, occurred after the burn'' and ``apparently attracted 
Dakota skippers from a nearby site'' (Skadsen 2008, p. 2). The 
Poweshiek skipperling is extirpated from both sites, but the reasons 
for its disappearance are not known (Service 2012, unpubl. data). At 
each site, prescribed fire and brush control are implemented on a 
rotational basis (Skadsen 2011, pp. 1-4); at Pickerel Lake State 
Recreation Area, forbs were planted in 2011 to diversify nectar 
resources for prairie butterflies (Skadsen 2011, pp. 2-4).
    A privately owned ranch with Dakota skippers in Day County, South 
Dakota, is managed with a patch burn grazing system in which each 
grazing unit is rested for a full year (Skadsen 2008, p. 10), which may 
be beneficial to the species. The effects of patch burn grazing at this 
site are being studied jointly by The Nature Conservancy and South 
Dakota State University (Skadsen 2008, p. 10).
    In 2005, the Service's National Wildlife Refuge System in North and 
South Dakota adopted the Conservation Strategy and Guidelines for 
Dakota Skippers on Service Lands in the Dakotas, which are based on the 
Service's Dakota Skipper Conservation Strategy and Guidelines and on 
versions of the Service's conservation guidelines for Dakota skipper. 
The guidelines were revised in March 2013 (http://www.fws.gov/midwest/endangered/insects/dask/DASKconservationguidelines2013.html). In the 
Dakotas, the Service plans to implement the conservation guidelines on 
all of its lands where the Dakota skipper is known to occur--the 
Service owns 12 Dakota skipper sites in the Dakotas where the species 
is considered present or has unknown occupancy. The guidelines also 
suggest that the Service examine other lands under its ownership to 
determine whether unrecorded populations of Dakota skippers may be 
present and to conduct surveys in those areas or manage the site in 
accordance with the Dakota Skipper Conservation Strategy and 
Guidelines. These guidelines will be reviewed and updated to reflect 
new information as it is developed.
Poweshiek Skipperling
    Most of the conservation initiatives discussed above were put in 
place to benefit the Dakota skipper, but may also benefit the Poweshiek 
skipperling. Conservation initiatives are also in place at several 
Poweshiek skipperling sites in Wisconsin and one or two sites in 
Michigan.
    At least two sites occupied by Poweshiek skipperling in Michigan 
are at least partially owned and managed by the Michigan Nature 
Association (MNA); however, the MNA does not specifically manage for 
Poweshiek skipperling conservation. The State of Michigan owns part or 
all of four occupied Poweshiek skipperling sites; however, most of 
those lands are managed as state recreational areas, not for prairie 
butterfly conservation. Landowners at one fen site are participating in 
a Michigan DNR Land Incentive Program, and a portion of another 
occupied site is part of the Burr Memorial Prairie Plant Preserve 
(Michigan Natural Features Inventory 2011, unpubl. data). The Poweshiek 
skipperling may benefit from conservation activities in place for the 
federally endangered Mitchell's satyr at one Michigan site.

[[Page 63609]]

    Poweshiek skipperling sites in Wisconsin are owned and managed by 
the Wisconsin DNR, who manage the land to maintain and improve prairie 
habitat. The Wisconsin DNR recently received a Sustain Our Great Lakes 
(SOGL) grant to conduct invasive species management on several SNAs, 
including Puchyan Prairie (Wisconsin DNR 2012, in litt.). The 
Scuppernong Prairie SNA, Wilton Road, and Kettle Moraine Low Prairie 
SNA are managed primarily through fire and invasive species control.
    Furthermore, the Minnesota Zoo recently initiated a propagation 
research program for the Poweshiek skipperling and Dakota skipper to 
develop methods to propagate this and other species in the future. If 
this program is successful, the conservation benefit could be possible 
if it could facilitate reintroduction and augmentation efforts into 
areas where the species has declined or disappeared. Furthermore, this 
propagation effort may lead to knowledge of basic biology and life 
history of both species.
    To summarize, the conservation initiatives discussed above may 
ameliorate one or more stressors on populations of Dakota skipper and 
Poweshiek skipperling at a relatively small number of sites. 
Approximately 12 Dakota skipper sites and 8 Poweshiek skipperling sites 
benefit from conservation easements; 12 Dakota skipper sites are owned 
by the Service and may benefit from implementation of Dakota skipper 
conservation guidelines; 2 sites in state parks are undergoing prairie 
restoration and management; approximately 5 additional Dakota skipper 
sites and 4 Poweshiek skipperling sites are managed to benefit prairie 
butterflies, such as rotational fire management. Since numerous sites 
have two or more stressors of moderate to high-level impacts to one or 
both species, all stressors are likely not completely ameliorated at 
many sites. Initiatives such as captive propagation and studies of the 
effects of various management techniques may be applied broadly and may 
be beneficial to each species as a whole--the timeframe for these 
benefits to be realized, however, will not be immediate.

Factor B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    Although its biology could make the Dakota skipper sensitive to 
collection at some locations, the present level of scientific 
collection is minimal and recreational collecting is unlikely (Royer 
and Marrone 1992a, p. 27). No collection threats are known or likely 
for the Poweshiek skipperling (Royer and Marrone 1992b, p. 16). 
Collection is not currently a threat to either species in Canada 
(COSEWIC 2003, p. 18). Scientific Collectors Permits are required in 
states where both species have legal protection, and permission is 
often required to collect specimens on protected areas. Furthermore, 
these species are not collected for commercial purposes; the drab 
coloration likely makes both species less desirable for collectors and 
the remoteness of occupied habitat and limited flight period would make 
recreational collections difficult (Borkin 2012, pers. comm.). 
Therefore, overutilization for commercial, recreational, scientific, or 
educational purposes is not currently a threat to Dakota skipper and 
Poweshiek skipperling.
    Although recreational collection is not a threat to these species 
at this time, due to the few populations, small population size, and 
restricted range, if any recreational collecting did occur in the 
future, even limited collection from the remaining small and isolated 
populations could have deleterious effects on these species' 
reproductive and genetic viability.

Factor C. Disease or Predation

    Diseases or parasites that are specific to the Dakota skipper or 
Poweshiek skipperling are not known, but some parasitism or predation 
likely occurs during each of the life stages. For example, 10 of 130 
eggs tagged for field observation in a 1994 study of a Wisconsin 
Poweshiek skipperling population appeared to have suffered from 
predation or parasitism (Borkin 1995b, p. 5); some were punctured and 
had the contents extracted, and others turned black and dried up. Dana 
(1991, pp. 19-21) documented some parasitism of Dakota skipper and 
Ottoe skipper (Hesperia ottoe) eggs and larvae by various wasp and ant 
species and predation by various insects. Wolbachia, ubiquitous 
intercellular bacteria estimated to affect 20-70 percent of all insect 
species, including many butterfly species, affects the reproductive 
ecology of its host (Kodandaramaiah 2011, pp. 343-350). It is uncertain 
if Wolbachia are affecting the Dakota skipper or Poweshiek skipperling. 
The University of Michigan (at Dearborn) has plans to study Wolbachia 
bacteria on one or both of the species.
    Predation by birds or insects is not considered a major component 
of Dakota skipper or Poweshiek skipperling population dynamics and does 
not likely impact the species. McCabe (1981, p. 187), however, noted 
three kinds of predators to Dakota skippers, including Ambush bugs 
(Hemiptera: Phymata sp.), flower spiders (Aranaea: Misumena spp.), and 
orb weavers (various Araneldae). Although flower spiders and ambush 
bugs are effective predators of nectar-feeding insects (McCabe 1981, 
pp. 187-188) and may cause mortality to some individuals, no evidence 
indicates that these predators have population level impacts to either 
the Dakota skipper or Poweshiek skipperling. Similarly, Orb weaver 
spiders appear to be successful predators of ``old, warn individuals'' 
(McCabe 1981, p. 188), but no evidence indicates that these predators 
have population-level impacts to the Dakota skipper and Poweshiek 
skipperling.
    Therefore, we do not consider either disease or predation to be a 
significant stressor to the Dakota skipper or Poweshiek skipperling 
populations at this time, nor do we expect these stressors to become 
threats in the future.

Factor D. The Inadequacy of Existing Regulatory Mechanisms

    Existing regulatory mechanisms vary by location, but generally do 
not mitigate for the numerous threats that the Dakota skipper and 
Poweshiek skipperling face.
State Regulations
    The Dakota skipper is listed as threatened under Minnesota's 
endangered species statute. Under the Minnesota statute, a person may 
not take, import, transport, or sell any portion of an endangered 
species of wild animal or plant, or sell or possess with intent to sell 
an article made with any part of . . . an endangered species of wild 
animal or plant'' except as permitted by the Minnesota DNR (Minnesota 
Statutes 2012, 84.0895). The Poweshiek skipperling is listed as a 
species of special concern in Minnesota, which conveys no prohibitions 
against take of the species. The Minnesota DNR has proposed to list 
Poweshiek skipperling as endangered and to change the status of Dakota 
skipper from threatened to endangered (Minnesota DNR 2012), but it is 
unclear when this may go into effect. The Poweshiek skipperling is 
listed as threatened under state endangered species statutes in Iowa 
and Michigan and as endangered in Wisconsin. South Dakota has an 
endangered species act, but no invertebrates are currently listed. 
South Dakota put forth a proposal to add the Dakota skipper to the 
state endangered species act list, but it was not finalized. Although 
the Dakota skipper is not listed as threatened or endangered under 
South Dakota's endangered species statute, the State natural

[[Page 63610]]

heritage program considers the species to be imperiled because of 
rarity due to very restricted range and very few populations. North 
Dakota does not have a mechanism for conferring protection to 
threatened or endangered species at the State level.
    State Endangered species statutes provide state natural resource or 
conservation agencies with the authority to regulate collection of 
individuals and related activities (for Poweshiek skipperling in Iowa, 
Michigan, and Wisconsin and Dakota skipper in Minnesota), but we have 
no information to suggest that collection is a stressor that impacts 
populations of the species. With the exception of the regulation of 
some incidental take in Wisconsin and Minnesota, the statutory 
protections afforded by these state statutes may do little to protect 
or mitigate Poweshiek skipperling or Dakota skipper from non-collection 
threats. While some threats may result in direct mortality of both 
species, such as ill-timed fires, most threats to the species are 
indirect and state laws that regulate direct harm to the species do not 
address these threats. In Iowa, for example, Poweshiek skipperling 
populations are likely now extirpated due to habitat destruction and 
conversion and other undetermined threats, despite its presence on the 
State's list of threatened species since 1994. In Wisconsin, where 
threats from actions that may incidentally take Poweshiek skipperlings 
may be addressed in conservation plans, state endangered species 
protections do not protect the species from stochastic events and 
habitat fragmentation that are threats to the State's small and 
isolated populations.
Federal Regulations
    The U.S. Forest Service (Forest Service or USFS) has designated the 
Poweshiek skipperling and the Dakota skipper as sensitive species (a 
species identified by a Regional Forester for which population 
viability is a concern) in North Dakota (Forest Service 2011). The 
Forest Service's objectives for sensitive species benefit Dakota 
skipper and Poweshiek skipperling where they occur (or could occur) on 
USFS lands; however, the majority of populations of both species do not 
occur within USFS lands. The Poweshiek skipperling has been documented 
at two sites on the Sheyenne National Grasslands; however, it has not 
been observed since 2001 at one site and 1996 at the other. Therefore, 
these Forest Service objectives, although promising, have little 
ability to affect the rangewide status of the species. If Forest 
Service lands were to be occupied by either species in the future, 
these objectives may benefit the species at a local scale.
Canadian Regulations
    Dakota skipper and Poweshiek skipperling are listed as threatened 
under Canada's Species at Risk Act (SARA) (Environment Canada 2012. 
Species at Risk Act Public Registry. <http://www.registrelep-sararegistry.gc.ca/sar/index/default_e.cfm>. Accessed February 8, 
2012). Under SARA, take of both species is prohibited on Canadian 
Federal lands, but the Poweshiek skipperling occurs only on non-federal 
lands in Canada, and only four or five Dakota skipper sites are on 
Federal lands (Coalfields Community Pasture) in Canada. The Federal 
Cabinet may create an order extending SARA's powers (e.g., to private 
lands) if a species is insufficiently protected by provincial laws; 
however this has not been done for either of these species. The Dakota 
skipper is listed as threatened under the Manitoba Endangered Species 
Act, and it is therefore unlawful to kill, injure, possess, disturb, or 
interfere with the Dakota skipper; destroy, disturb, or interfere with 
its habitat; or damage, destroy, obstruct, or remove a natural resource 
on which the species depends for its life and propagation (Manitoba 
Endangered Species Act <http://www.gov.mb.ca/conservation/wildlife/legislation/endang_act.html> Accessed February 7, 2012). The Poweshiek 
skipperling was recently listed as endangered in Manitoba (<http://www.gov.mb.ca/conservation/wildlife/sar/sarlist.html> Accessed December 
28, 2012). There is no legal basis for protecting threatened or 
endangered invertebrates in Saskatchewan, but since both species are 
listed under SARA, the national government could step in to protect the 
species in the province if the province does not act to protect the 
species (Environment Canada. 2012. Species at Risk Act: A Guide. 
<http://www.sararegistry.gc.ca/approach/act/Guide_e.cfm> Accessed 
February 7, 2012).
    To summarize, some of the regulatory mechanisms discussed above are 
beneficial to populations of Dakota skipper and Poweshiek skipperling 
at a local scale; however, most do not ameliorate stressors except for 
harm to individuals in certain states. With the exception of the 
regulation of some incidental take in Wisconsin, Minnesota, and Canada, 
the statutory protections afforded by these statutes may do little to 
protect Poweshiek skipperling or Dakota skipper from non-collection 
stressors.

Factor E. Other Natural or Manmade Factors Affecting Its Continued 
Existence

Habitat Fragmentation and Population Isolation
    As habitat specialists, habitat fragmentation has a strong negative 
effect on the distribution and abundance of the Dakota skipper and 
Poweshiek skipperling because both are dependent on remnant native 
tallgrass prairie or native mixed-grass prairie and, in Michigan, 
Poweshiek skipperling depends on native prairie fens. Habitat 
fragmentation reduced once extensive areas of these habitats to a 
collection of patches of varying quality and isolation. The probability 
of extinction within patches can be determined primarily by degradation 
of habitat quality, management techniques (e.g., haying, prescribed 
burns), and likelihood of stochastic events, such as wildfire or 
floods.
    Although there are no genetic studies on the Poweshiek skipperling, 
fragmentation of tallgrass prairie has degraded the genetic diversity 
of remaining Dakota skipper populations (Britten and Glasford 2002, pp. 
371-372). What may have once been a single population of Dakota 
skippers spread across formerly extensive tallgrass and mixed-grass 
prairie (McCabe 1981, p. 184) is now fragmented into about 172 separate 
sites where the species is known to be or may still be present (sites 
with present (91) or unknown (81) status). The small genetic 
differences among seven Dakota skipper populations in the southern 
portion of the species' range suggest that they were formerly connected 
(Britten and Glasford 2002, pp. 371-372). Each Dakota skipper 
population is now subject to genetic drift that may erode its genetic 
variability over time and possesses genetic qualities indicative of 
inbreeding (Britten and Glasford 2002, pp. 371-372). Inbreeding lowers 
the capacity of local populations to adapt to environmental changes and 
may magnify the effect of deleterious alleles (genes with undesirable 
effects on individuals or populations) (Nieminen et al. 2001, pp. 242-
243).
    Poweshiek skipperlings are not wide dispersers (Burke et al. 2011, 
p. 2279; Fitzsimmons 2012, pers. comm.); species experts have estimated 
maximum dispersal distance to be less than 1.6 km (1.0 mi) (Westwood 
2012b, pers. comm; Dana 2012b, pers. comm.). Its mobility, however, has 
been ranked as less than that of Dakota skipper (Burke et al. 2011, p. 
2279; Fitzsimmons 2012, pers. comm.); therefore, a more conservative 
maximum dispersal

[[Page 63611]]

distance may be more similar to that of the Dakota skipper (less than 1 
km (0.6 mi)). Most individuals may remain within a single habitat patch 
during their 5-7 day adult life span; therefore, local extinctions of 
the Poweshiek skipperling on isolated habitat fragments are likely 
permanent unless one or more populations located within 1.0-1.6 km 
(0.6-1.0 mi) are large enough to produce immigrants to reestablish 
populations. Furthermore, fragmentation of tallgrass prairie began in 
about 1830, and at least 85 to 99 percent of the original prairie is 
now gone across the species' ranges (Samson and Knopf 1994, p. 419). As 
a result, Poweshiek skipperling and Dakota skipper populations are now 
scattered in fragments of this once vast ecosystem. The Poweshiek 
skipperling may not move across barriers; for instance, in Manitoba, 
Poweshiek skipperlings have been observed avoiding dispersal over short 
distances, even to suitable habitat, if a barrier such as a road exists 
between suitable prairie habitat or nectar sources (Westwood et al. 
2012, p.18). Repopulation of Poweshiek skipperling sites after 
extirpation has been observed (e.g., after a flood) (Saunders 1995, p. 
15), but source populations need to be adjacent or very close.
    Similarly, Dakota skippers have a short (5- to 7-day) life span 
(Dana 1991, p. 32) and an estimated maximum dispersal distance to be no 
greater than 1 km (0.6 mi) between patches of prairie habitat separated 
by structurally similar habitats (Cochrane and Delphey 2002, pp. 6, 
32). Therefore, Dakota skipper and Poweshiek skipperling habitat 
patches separated by more than 1 km (0.6 mi) are effectively isolated 
from one another (McCabe 1981, p. 190; Swengel 1998). Extirpation of 
small, isolated populations may occur over many years in some cases, 
but may be inevitable where immigration from nearby populations is not 
possible (Hanski et al. 1996, p. 535).
    Because Dakota skipper and Poweshiek skipperling habitat is highly 
fragmented and because the species are subject to local extinction, 
their ability to disperse to reoccupy vacant habitat patches may be 
crucial for their long-term persistence. Patch isolation and decreased 
permeability of surrounding habitat acts as a dispersal barrier between 
patches, ultimately decreasing genetic diversity within the patch 
through genetic drift and inbreeding. If we assume isolation occurs 
when a patch is more than 1.6 km (1.0 mi) from another patch, then 
about 45 percent of Poweshiek skipperling locations with present or 
unknown status are effectively isolated, and would not be recolonized 
if extirpated (Service 2012 unpubl. data; Service 2013, unpubl. data). 
Using a more conservative maximum dispersal of 1.0 km (0.6 mi), 
approximately 56 percent of Poweshiek skipperling locations with 
present or unknown status are effectively isolated. Isolation was a 
factor in loss of a site at Hartford Beach State Park, South Dakota, 
where the Poweshiek skipperling was extirpated due to habitat 
succession and exotic plant invasion (Skadsen 2009, p. 4; Skadsen 2010, 
pers. comm.), but was located too far from a source population for 
natural recolonization to occur. Improved prairie management has since 
markedly improved habitat quality, but the species has not been 
detected since 2006 at Hartford Beach State Park (Skadsen 2009, p. 4; 
Skadsen 2012, p. 4; Service 2013, unpubl. data). For Dakota skipper, if 
we use a maximum dispersal distance of 1 km (0.6 miles), approximately 
84 percent of Dakota skipper sites with present or unknown status are 
effectively isolated.
    This simple analysis, however, probably underestimates the impacts 
of habitat fragmentation on the species. Populations of both species 
may only be near others that are too small to produce sufficient 
numbers of immigrants. This is true for the Poweshiek skipperling in 
Scuppernong Prairie in Wisconsin, for example, which is about 0.3 km 
(0.2 mi) from the Wilton Road population; fewer than 100 individuals 
have been counted at this site each year (See Population Distribution 
and Status). Numbers at Wilton Road are currently too small (less than 
12 individuals counted each year) to produce sufficient numbers of 
emigrants to Scuppernong Prairie to reestablish a viable population in 
the event of the latter's extirpation. There is no population of 
Poweshiek skipperlings near the Puchyan Prairie site (which is about 
100 km (62 mi) from the nearest site in Wisconsin); additionally, only 
a few individuals have been observed at this site each year. In North 
Dakota, Orwig (1997, p. 3) found that a 6 ha (15 ac) patch of Poweshiek 
skipperling habitat at Hartleben Prairie was connected by grassland to 
another Poweshiek skipperling population, but neither was considered a 
robust population. Only 2 of the 11 Poweshiek skipperling sites with 
present status in Michigan are located within 1 mi (1.6 km) of another 
site; the rest are completely isolated from other populations. 
Furthermore, most of these populations consist of few individuals (see 
Population Distribution and Status). Poweshiek skipperlings at Little 
Goose Lake Fen, for example, are separated from other populations by at 
least 8 km (5 mi)--too far for immigrants to repopulate the site. 
Furthermore, Little Goose Lake Fen may contain too few Poweshiek 
skipperlings (Michigan Natural Features Inventory 2011, unpubl. data) 
to generate sufficient numbers of immigrants. In addition, poor habitat 
quality negatively influences the number and quality of emigrants 
(Thomas et al. 2001, p. 1795; Matter et al. 2009, p. 1467). Isolation 
is not likely alleviated by connections to low-quality habitats that 
are not capable of producing emigrants at the numbers or frequency 
sufficient to reliably repopulate nearby patches.
    Even with proper prairie management, extreme weather patterns or 
severe weather events may significantly impact Poweshiek skipperling 
and Dakota skipper populations, because they can occur across a large 
geographic area. These events include extremely harsh winters, late 
hard frosts following a spring thaw, severe storms, flooding, fire, or 
cool damp conditions. Habitats isolated as a result of fragmentation 
will not be recolonized naturally after local extirpations, as 
described above. Dakota skipper and Poweshiek skipperling numbers may 
decline due to the extirpation of isolated local populations where 
recolonization is no longer possible, even without further habitat 
destruction (Schweitzer 1989, unpaginated). The likelihood of 
population extirpation may be directly related to the size of habitat 
fragments. For example, in systematic surveys on Minnesota prairies, 
Swengel and Swengel (1997, pp. 134-137; 1999, p. 284) found no Dakota 
skippers on the smallest remnants (less than 20 ha (49 ac)), and 
significantly lower abundance on intermediate size (30-130 ha (74-321 
ac)) than on larger tracts (greater than 140 ha (346 ac)). These 
differences were unrelated to vegetation characteristics; habitat area 
did not correlate significantly with vegetation type, quality, or 
topographic diversity (Swengel and Swengel 1999, p. 284).
    We assessed the stressor of small size and isolation of habitat for 
143 Dakota skipper sites and 68 Poweshiek skipperling sites with 
present or unknown status--many of the sites with where the species is 
present in Canada were not evaluated because we had little or no 
information on the size of sites (Service 2012 unpubl. data; Service 
2013, unpubl. data). We considered small size and isolation of habitat 
to be a stressor with a low-level impact on populations at sites that 
contain more than 140 ha (346 ac) of native prairie or

[[Page 63612]]

the species' habitat onsite is located less than 1 km (0.6 mi) from 
habitat occupied by the species on another site. If the sum of native 
prairie on the site under review plus that on the nearby site(s) is 
less than 140 ha (346 ac), then this threat was considered to have a 
moderate or high impact on populations. We considered small size and 
isolation of habitat to be a stressor with moderate impacts on 
populations at sites where the species' habitat is greater than 1 km 
(0.6 mi) from any other area where the species is present, but contains 
more than 30 ha (74 ac) of habitat for the species; or where the 
species' habitat is less than 1 km (0.6 mi) from occupied Dakota 
skipper and Poweshiek skipperling habitat on another site, but the sum 
of native prairie on the site under review plus that on the nearby 
site(s) is less than 140 ha (346 ac) and greater than 30 ha (74 ac). 
Sites that contain a small area of Dakota skipper and Poweshiek 
skipperling habitat--no more than 30 ha (74 ac)--and that are not 
within 1 km (0.6 mi) estimated maximum dispersal distance of occupied 
Dakota skipper habitat are considered to have a stressor of high 
magnitude to those populations due to a combination of their small size 
and isolation.
    Dakota skipper populations on about 35 percent of the evaluated 
sites (50 of 143 sites) face a high level of impact to populations due 
to a combination of size and isolation (Service 2012, 2013, unpubl. 
data). Approximately 24 percent of evaluated sites (35 sites) face a 
moderate level of impact to populations due to small size and 
isolation. About 40 percent of Dakota skipper sites (50 of the 143 
evaluated sites) in the United States inhabit sites that are either 
sufficiently large (greater than 130 ha (346 ac)) or are close enough 
to other Dakota skipper populations that small size and isolation is 
not a stressor. Similarly, the stressor of small size and isolation has 
a high level of impact on Poweshiek skipperling populations on about 37 
percent of rated sites (25 of 68 sites), on 24 sites (35 percent) the 
threat is considered to have a moderate level of impact to populations, 
and on 28 percent (19 of the 68 evaluated sites) of the sites, we do 
not consider a small size and isolation to be a stressor. In a separate 
analysis strictly looking at distances between Poweshiek skipperling 
sites where the species is present, we found that only 2 sites are 
within 1 km (0.6 mi) of another site where the species is present 
(Service 2013, unpubl geodatabase).
    In summary, small, isolated populations face a current and ongoing 
stressor of moderate to high severity to both the Dakota skipper and 
Poweshiek skipperling. The stressor has a high impact to populations 
when isolation is combined with small habitat fragments or small 
populations; for example, where the population is too small to 
supplement nearby populations without adverse genetic consequences to 
the source population. Isolated populations occur throughout both 
species' entire ranges; only two percent of Poweshiek sites with 
present or unknown status are within the estimated maximum dispersal 
distance from one another as are about 16 percent of Dakota skipper 
sites with present or unknown occupancy. The small populations are 
subject to erosion of genetic variability leading to inbreeding, which 
lowers the ability of the species to adapt to environmental change. 
Small populations occur rangewide for both species; for example, 
surveyors have counted fewer than 100 individuals in all but 4 
Poweshiek skipperling sites in 2011 and all but one site surveyed in 
2012.
Climate Change
    Our analyses under the Act include consideration of ongoing and 
projected changes in climate. The terms ``climate'' and ``climate 
change'' are defined by the Intergovernmental Panel on Climate Change 
(IPCC). The term ``climate'' refers to the mean and variability of 
different types of weather conditions over time, with 30 years being a 
typical period for such measurements, although shorter or longer 
periods also may be used (IPCC 2007a, p. 78). The term ``climate 
change'' thus refers to a change in the mean or variability of one or 
more measures of climate (e.g., temperature or precipitation) that 
persists for an extended period, typically decades or longer, whether 
the change is due to natural variability, human activity, or both (IPCC 
2007a, p. 78).
    Scientific measurements spanning several decades demonstrate that 
changes in climate are occurring, and that the rate of change has been 
faster since the 1950s. Examples include warming of the global climate 
system, and substantial increases in precipitation in some regions of 
the world and decreases in other regions. (For these and other 
examples, see IPCC 2007a, p. 30; and Solomon et al. 2007, pp. 35-54, 
82-85). Results of scientific analyses presented by the IPCC show that 
most of the observed increase in global average temperature since the 
mid-20th century cannot be explained by natural variability in climate, 
and is ``very likely'' (defined by the IPCC as 90 percent or higher 
probability) due to the observed increase in greenhouse gas (GHG) 
concentrations in the atmosphere as a result of human activities, 
particularly carbon dioxide emissions from use of fossil fuels (IPCC 
2007a, pp. 5-6 and figures SPM.3 and SPM.4; Solomon et al. 2007, pp. 
21-35). Further confirmation of the role of GHGs comes from analyses by 
Huber and Knutti (2011, p. 4), who concluded it is extremely likely 
that approximately 75 percent of global warming since 1950 has been 
caused by human activities.
    Scientists use a variety of climate models, which include 
consideration of natural processes and variability, as well as various 
scenarios of potential levels and timing of GHG emissions, to evaluate 
the causes of changes already observed and to project future changes in 
temperature and other climate conditions (Meehl et al. 2007, entire; 
Ganguly et al. 2009, pp. 11555, 15558; Prinn et al. 2011, pp. 527, 
529). All combinations of models and emissions scenarios yield very 
similar projections of increases in the most common measure of climate 
change, average global surface temperature (commonly known as global 
warming), until about 2030. Although projections of the magnitude and 
rate of warming differ after about 2030, the overall trajectory of all 
the projections is one of increased global warming through the end of 
this century, even for the projections based on scenarios that assume 
that GHG emissions will stabilize or decline. Thus, there is strong 
scientific support for projections that warming will continue through 
the 21st century, and that the magnitude and rate of change will be 
influenced substantially by the extent of GHG emissions (IPCC 2007a, 
pp. 44-45; Meehl et al. 2007, pp. 760-764 and 797-811; Ganguly et al. 
2009, pp. 15555-15558; Prinn et al. 2011, pp. 527, 529). (See IPCC 
2007b, p. 8, for a summary of other global projections of climate-
related changes, such as frequency of heat waves and changes in 
precipitation. Also see IPCC 2011(entire) for a summary of observations 
and projections of extreme climate events.)
    Various changes in climate may have direct or indirect effects on 
species. These effects may be positive, neutral, or negative, and they 
may change over time, depending on the species and other relevant 
considerations, such as interactions of climate with other variables 
(e.g., habitat fragmentation) (IPCC 2007, pp. 8-14, 18-19). Identifying 
likely effects often involves aspects of climate change vulnerability 
analysis. Vulnerability refers to the degree to which a species (or 
system) is susceptible to, and unable to cope with,

[[Page 63613]]

adverse effects of climate change, including climate variability and 
extremes. Vulnerability is a function of the type, magnitude, and rate 
of climate change and variation to which a species is exposed, its 
sensitivity, and its adaptive capacity (IPCC 2007a, p. 89; see also 
Glick et al. 2011, pp. 19-22). There is no single method for conducting 
such analyses that applies to all situations (Glick et al. 2011, p. 3). 
We use our expert judgment and appropriate analytical approaches to 
weigh relevant information, including uncertainty, in our consideration 
of various aspects of climate change.
    As is the case with all stressors that we assess, even if we 
conclude that a species is currently affected or is likely to be 
affected in a negative way by one or more climate-related impacts, it 
does not necessarily follow that the species meets the definition of an 
``endangered species'' or a ``threatened species'' under the Act. If a 
species is listed as endangered or threatened, knowledge regarding the 
vulnerability of the species to, and known or anticipated impacts from, 
climate-associated changes in environmental conditions can be used to 
help devise appropriate strategies for its recovery.
    Global climate change, with projections of increased variability in 
weather patterns and greater frequency of severe weather events, as 
well as warmer average temperatures, would affect remnant prairie 
habitats and prairie fen habitats and may be a threat that has 
significant impacts on prairie butterflies such as Dakota skippers and 
Poweshiek skipperling (Royer and Marrone 1992b, p. 12; Royer and 
Marrone 1992a, pp. 22-23; Swengel et al. 2011, p. 336; Landis et al. 
2012, p. 140). For example, climatic factors, particularly 
precipitation and evaporation, play an important role in defining 
suitable Dakota skipper habitat (McCabe 1981, pp. 189-192). Larval 
Dakota skipper have ``hydrofuge glands'' that suggest an historical or 
present need of the species for protection from flooding (McCabe 1981, 
p. 181). Royer et al. (2008, p. 2) hypothesize that temperature and 
relative humidity at or near the soil surface may be important factors 
dictating larval survival, particularly since early stages live in a 
silken nest within a few centimeters (2-3) (0.8-1.2 in) of the soil 
surface during most of the summer (McCabe 1981, pp. 180-181, 189; Dana 
1991, p. 16). Furthermore, both species and their habitats may 
experience the effects of gradual shifts in plant communities and an 
increase in catastrophic events (such as severe storms, flooding, and 
fire) due to climate change, which are exacerbated by habitat 
fragmentation. Isolated populations, specifically, Dakota skipper 
populations and Poweshiek skipperling populations that are separated by 
more than about 1 km (0.6 miles), are unlikely to recover from local 
catastrophes unless sufficient numbers are successfully reintroduced, 
for instance, through artificial propagation efforts.
    Documentation of climate-related changes that have already occurred 
throughout the range of the Dakota skipper and Poweshiek skipperling 
(Johnson et al. 2005, pp. 863-871) and predictions of changes in annual 
temperature and precipitation in the Midwest region of the United 
States, such as Minnesota prairies (Galatowitsch et al. 2009, pp. 
2017), Michigan fens (Landis et al. 2012, p. 140), and throughout North 
America (IPCC 2007, p. 9) indicate that increased severity and 
frequency of droughts, floods, fires, and other climate-related changes 
will continue in the future. Recent studies have linked climate change 
to observed or predicted changes in distribution or population size of 
insects, particularly Lepidoptera (Wilson and Maclean 2011, p. 262). 
Native remnant prairies have been reduced by 85 to 99.9 percent across 
the range of both species (Samson and Knof 1994, p. 419)--this fact, 
coupled with the low dispersal ability of both species, makes it 
unlikely that populations may expand to new areas, for example, in a 
northward direction, to adapt to changing climate. Climate change is a 
threat that has the potential to have severe impacts on the species; 
however, at this time our knowledge of how these impacts may play out 
is limited. All of the sites within the range of both species are in an 
area that could experience the effects of climate change.
Prairie Plant Harvesting
    A potential, future threat to the Dakota skipper and Poweshiek 
skipperling is collection of purple coneflower (blacksamson echinacea), 
a predominate nectar source for both species, for the commercial herbal 
remedy market (Skadsen 1997, p. 30). Biologists surveying skipper 
habitats have not reported signs of plant collecting, but illegal or 
unregulated harvest could become a problem in Dakota skipper and 
Poweshiek skipperling habitats due to economic demand (Skadsen 1997, p. 
30). Currently, prairie plant harvesting is not considered a threat 
that impacts the species; however, this situation may change if the 
demand for echinacea increases.
Management for Invasive Species and Succession
    Native prairie and native prairie fens must be managed to prevent 
the indirect effects of invasive species and succession (processes of 
change in species structure to an ecological community over time; 
secondary succession is a disruption to succession that occurs due to 
an event such as fire) to Dakota skippers and Poweshiek skipperlings. 
If succession progresses too far, established shrubs or trees must be 
removed in a way that avoids or minimizes damage to the native prairie. 
When succession is well advanced, managers must use intensive methods, 
including intensive fire management, to restore prairie plant 
communities. If not done carefully, these actions may themselves harm 
local populations of the butterflies (for example, see Factor A. The 
Present or Threatened Destruction, Modification, or Curtailment of Its 
Habitat or Range). For example, once smooth brome has invaded Poweshiek 
skipperling or Dakota skipper habitat, it is challenging to eradicate 
it while minimizing harm to the butterflies. Willson and Stubbendiecks 
(2000, p. 36) recommended burning prairie habitats, annually in some 
cases, to control smooth brome at the stage when the lateral shoots are 
elongating. In southwest Minnesota and in other parts of Dakota 
skipper's range, the optimum time to burn to control smooth brome may 
occur during the time that the adult butterflies are active. Cutting or 
grazing to remove smooth brome may have less intensive effects on 
Poweshiek skipperling and Dakota skipper larvae and could be used as an 
alternative to fire, although these techniques also pose a risk to both 
species if carried out annually at isolated sites. Puchyan Prairie is 
another example of a small and isolated population that is susceptible 
to invasive species control efforts, if they are not conducted properly 
(Swengel and Swengel 2012, p. 6), although the Wisconsin DNR proposed 
control efforts that may improve habitat by removing reed canary grass, 
Canada thistle, and glossy buckthorn (Wisconsin DNR 2012 in litt.; 
Carnes 2012, in litt.).
    If not appropriately managed with fire, grazing, or haying, 
Poweshiek skipperling and Dakota skipper habitat is degraded due to 
reduced diversity of native prairie plants and eventually succeeds to 
shrubby or forested habitats that are not suitable for either species. 
At Hartford Beach State Park in South Dakota, for example, the 
Poweshiek skipperling was extirpated (Skadsen

[[Page 63614]]

2009, p. 4) after lack of management led to invasion by smooth sumac 
(Rhus glabra) and quaking aspen (Populus tremuloides) (Skadsen 2006a, 
p. 5). Lack of management may also increase the likelihood of invasion 
of exotic cool-season grasses, such as Kentucky bluegrass and smooth 
brome (Mueller 2013, pers. comm.), which do not grow when Dakota 
skipper and Poweshiek skipperling larvae are feeding; thus a prevalence 
of these grasses reduces food availability for the larvae.
    As with invasive species, actions intended to reverse secondary 
succession may be intensive and can themselves affect Poweshiek 
skipperling and Dakota skipper populations. For example, Poweshiek 
skipperling populations failed to recover after prescribed burns were 
carried out at Kettle Moraine Low Prairie SNA after it had become 
overgrown (Borkin 2011, in litt.).
    Broadcast chemical control of exotic plants such as aerial spraying 
of leafy spurge and application of broad-spectrum herbicides to control 
weeds in pastures also eliminates native forbs that are important 
nectar sources for both species (Royer and Marrone 1992a, pp. 10, 16, 
28, 29, 33, 1992b, p. 17, Orwig 1997, p. 7). For example, invasion of 
native prairie by exotic species, primarily leafy spurge and Kentucky 
bluegrass, as well as chemical control of exotic species, are 
documented threats to Dakota skippers at about 12 sites in North Dakota 
(Royer and Royer 2012b, pp. 15-16, 22-23). In repeated surveys, Royer 
and Marrone (1992a, p. 33) observed a correlation between the 
disappearance of the Dakota skipper and the advent of chemical weed 
control methods in North Dakota, including the Sheyenne National 
Grasslands. Royer and Marrone (1992b, p. 17), cited the combination of 
drought and grasshopper control programs along the Red River Valley as 
having serious impacts on the Poweshiek skipperling. Dana (1997, p. 5) 
concluded that herbicide use for weed and brush control on private 
lands is the principal threat to the Hole-in-the-Mountain complex in 
Minnesota, where both butterfly species have been documented. 
Furthermore, herbicide or pesticide use in concert with other 
management types may amplify other threats to the butterflies. Skadsen 
(2006b, p. 11), for example, documented the likely extirpation of the 
Poweshiek skipperling at Knapp Ranch in South Dakota after a July 2006 
application of broadleaf herbicide associated with heavy grazing. The 
degree and immediacy of the threat posed by broadcast application of 
herbicides or pesticides is not precisely understood, but may be mostly 
tied to the use of herbicides to control invasive species on 
rangelands. If broad applications of herbicides are used in ways that 
remove plants from rangelands that are important for Poweshiek 
skipperling or Dakota skipper, then this is a potential threat on all 
privately owned sites where broadcast applications may occur.
    Indiscriminant use of insecticides for pest control on rangeland, 
adjacent cropland, or forests is a stressor to populations of Poweshiek 
skipperling and Dakota skipper. Insecticides used in agriculture, urban 
gardens, and forests are a suspected cause of Colony Collapse Disorder 
in bees by reducing resistance to parasites and pathogens and may have 
similar effects on other insects (Beyers 2012, p. 1). Neonicotinyl 
pesticides, such as the imidacloprid compound, for example, are a 
commonly used seed dressing that spreads to nectar and pollen of 
flowering crops (Whitehorn 2012, p. 1). The spread of nonnative gypsy 
moths (Lymantria dispar dispar) has increased efforts to control this 
damaging species and may also pose a threat, especially in the range of 
Poweshiek skipperling. Insecticides used in the gypsy moth suppression 
programs typically include Foray, a formulation of the bacterial 
insecticide Bacillus thuringiensis kurstakii (Btk), or Gypchek, a viral 
insecticide specific to gypsy moth caterpillars. Btk is known to be 
lethal to butterfly larvae (e.g., Karner blue butterfly) (Carnes 2011, 
p. 1). In Wisconsin, the gypsy moth suppression program is managed 
under State Statute 26.30 and Natural Resources Board Rule number 47, 
and Gypchek is used when endangered or threatened moths or butterflies 
are present (Wisconsin DNR, http://dnr.wi.gov/topic/ForestHealth/GypsyMothPesticides.html, accessed May 24, 2012).
    Herbicide and pesticide use was assessed at 16 present and unknown 
Dakota skipper sites and 10 Poweshiek skipperling sites occupied with 
present or unknown occupancy where we had sufficient information to 
evaluate the stressor (Service 2012, 2013, unpubl. data). We considered 
the level of impact to populations posed by herbicide and pesticide use 
to be low if herbicides or pesticides are used, if the site is only 
spot sprayed when and where necessary (Smart et al. 2011, p. 182) and 
their use is not expected to change in the future. The level of threat 
was considered to be moderate if the use of herbicides is likely to 
increase at a site (e.g., in response to new or expanding invasive 
species), but Dakota skipper and Poweshiek skipperling habitat is 
unlikely to be exposed to broadcast applications. The level of impact 
to populations posed by herbicide and pesticide use was considered to 
be high at sites where herbicides are likely to be broadcast over the 
entire site at least once every four years, or herbicide use has 
significantly reduced forb or nectar plant density and diversity or is 
likely to in the future. The level of impact to populations posed by 
herbicide and pesticide use was high at 5 of the 16 assessed Dakota 
skipper sites (2 in North Dakota and 3 in South Dakota) and moderate at 
2 sites--one in North Dakota and one in South Dakota. The level of 
impact to populations posed by herbicide and pesticide use was 
considered to be high at 3 of the 10 assessed Poweshiek skipperling 
sites (all 3 in South Dakota), and 1 site in North Dakota had a 
moderate level of impact to populations.
    In summary, some efforts to manage woody encroachment and invasive 
species, such as herbicide use, can be a stressor to both Dakota 
skipper and Poweshiek skipperling populations. Invasive species 
management is a current and ongoing threat of low to high impact to 
populations, depending on the intensity and extent of the use, types of 
techniques, and the compounding effects that may occur from varying 
management. Medium- to high-level impacts of herbicide or pesticide use 
to Dakota skipper and Poweshiek skipperling populations have been 
documented in North and South Dakota. This stressor has a high impact 
to populations when it is combined with other stressors, such as 
management, that reduces or eliminates nectar food sources, or small 
habitat fragments that are isolated from other source populations that 
may replenish individuals killed by pesticides. Herbicide and pesticide 
use may have direct or indirect effects on Dakota skipper and Poweshiek 
skipperling. Although such activities occur, there is no evidence that 
these activities alone have significant impacts on either species, 
since their effects are often localized. However, these factors may 
have a cumulative effect on the Dakota skipper and Poweshiek 
skipperling when added to habitat curtailment and destruction because 
dramatic population declines have occurred in both species (discussed 
in Factor A). Invasive species and woody vegetation management helps to 
maintain prairie habitats and can also be beneficial to populations of 
both species, for example, when concentrated on affected areas through 
spot spraying.

[[Page 63615]]

Pharmaceuticals
    The effect of pharmaceutical residues in the environment on 
nontarget animals is an emerging concern (Lange et al. 2009). 
Ivermectin, a widely used and persistent veterinary pharmaceutical used 
to treat cattle, is a chemical of emerging concern to the Dakota 
skipper and Poweshiek skipperling. Ivermectin is an anthelmintic (drugs 
that are used to treat infections with parasitic worms) that is spread 
to prairie environments via the dung of grazing cattle (Lange et al. 
2009, p. 2238). Lange et al. (2009, pp. 2234, 2238) found that skipper 
butterflies are particularly vulnerable to ivermectin, due to their low 
dispersive capacities and habitat preferences for soil. The extirpation 
of the Dakota skipper in at least one South Dakota site (Sica Hollow 
West) is possibly due to ivermectin that has leached into the 
environment (Skadsen 2010, pers. comm.).
    Pharmaceutical use is a stressor that has the potential to have 
high-level impacts on populations of the Dakota skipper and Poweshiek 
skipperling; however, at this time our knowledge of these impacts is 
limited. Sites within the range of both species could experience the 
effects of pharmaceuticals. Sites that experience grazing, however, are 
particularly vulnerable to ivermectin use; these sites are primarily in 
South Dakota, North Dakota, and Minnesota. The use of pharmaceuticals 
such as ivermectin may have a cumulative effect on the Dakota skipper 
and Poweshiek skipperling when added to habitat curtailment or 
destruction, because habitat destruction leads to population declines 
in populations of both species (discussed in Factor A).
Unknown Stressors Causing Population Declines
    The sharp and broad declines of Poweshiek skipperling documented in 
Iowa, Minnesota, North Dakota, and South Dakota are indicative of a 
response to one or more stressors that have yet to be ascertained. 
These unknown factors may consist of a combination of one or more of 
the threats described throughout Factors A, C and E of this proposed 
rule, or may be something that has not yet been identified. These 
declines are reminiscent of the widely publicized decline of honey bees 
(Apis mellifera) in that they seem sudden and mysterious (Spivak et al. 
2011, p. 34).
    One or more unidentified stressors have strongly impacted Poweshiek 
skipperling populations in the western portion of its range, which 
contains more than 80 percent of the species' site records. Unknown 
stressors may be the current threat with the most significant impacts 
to Poweshiek skipperling in Minnesota, North Dakota, and South Dakota, 
where populations experienced a sudden decline to undetectable numbers 
after about 2003. Until about 2003, Poweshiek skipperling was regarded 
as the most frequently and reliably encountered prairie-obligate 
skipper in Minnesota, which contains nearly 50 percent of all known 
Poweshiek skipperling locations. Numbers and distribution dropped 
dramatically in subsequent years, however, and the species has not been 
seen in Minnesota since 2007. Similar recent dramatic declines were 
observed in North Dakota, South Dakota, and Iowa (See Background of 
this rule).
    Recent declines of Dakota skippers indicate that this species may 
also be impacted by unknown stressors. The Dakota skipper was last 
detected at one site in Iowa in 1992. Only one individual was detected 
in Minnesota during 2012 surveys, which included 18 sites with previous 
records; surveys for undiscovered populations were also carried out on 
23 prairie remnants without previous records for the species. Based on 
similar conditions in other parts of the species' range, similar trends 
are anticipated outside of Minnesota. Indications of recent declining 
trends have been observed in South Dakota and North Dakota. In South 
Dakota, for example, the proportion of positive surveys at known sites 
has fluctuated over time; however, the 2012 surveys had the lowest 
positive detection rate (35 percent) for the last 15 years (since 
1996)--much less than comparable survey years in South Dakota (for 
years with more than 20 surveys). The Dakota skipper was detected at 12 
of the 23 sites surveyed during 2012 in North Dakota (and 2 additional 
sites with no previous Dakota skipper records); average encounter 
frequencies observed across the State in 2012 (9.4 encounters per 
hour), however, were about half of those observed during the 1996-1997 
statewide surveys (ND state average = 17.4 encounters per hour). Recent 
survey results and similar life histories suggest that the Dakota 
skipper can be reasonably compared to the Poweshiek skipperling in 
their potential rate of decline--that is, it is reasonable to assume 
that Dakota skipper may be vulnerable to the same unidentified factors 
that have caused dramatic declines in the Poweshiek skipperling, with a 
slight delay in timing.
    In summary, the results of extensive surveys in the western portion 
of the Poweshiek skipperling's range have documented the species' 
response to unknown stressors and indicate that they are a current 
threat of high severity. Although to date the Dakota skipper has not 
experienced such dramatic declines as the Poweshiek skipperling, 
similar unknown stressors on Dakota skipper populations likely have 
affected the species in Minnesota and Iowa, where recent surveys 
indicate that the species may be absent or at undetectable levels.
Summary of Factor E
    Based on our analysis of the best available information, we have 
identified several natural and manmade factors affecting the continued 
existence of the Dakota skipper and Poweshiek skipperling. Effects of 
small population size, population isolation, and loss of genetic 
diversity are likely threats that have significant impacts on both 
species. Environmental effects resulting from climatic change, 
including increased flooding and drought, are expected to become severe 
in the future and result in additional habitat losses; however, we have 
limited information on how this stressor may affect either species. 
Possibly the threat with the most significant impacts to the Poweshiek 
skipperling are one or more unknown stressors that have led to 
widespread and sharp population declines in the western portion of the 
species' range. These unknown stressors may also be the cause of the 
recent declines observed in Dakota skipper populations over much of its 
range. Anthropogenic factors such as insecticides, herbicide and 
pesticide use, and prairie plant harvest are also threats to both 
species. Collectively, these threats have operated in the past, are 
impacting both species now, and will continue to impact the Dakota 
skipper and Poweshiek skipperling in the future.
Conservation Efforts To Reduce Other Natural or Manmade Factors 
Affecting Its Continued Existence
    Several of the conservation activities discussed under Factor A. in 
this rule may address some factors discussed under Factor E, for 
example life-history studies of both species, studies to examine the 
effects of various management strategies on the species and its 
habitat, and habitat restoration techniques such as controlled burns on 
sites divided into several management units.
    The Minnesota Zoo has initiated a new program to research Poweshiek 
skipperling and Dakota skipper

[[Page 63616]]

propagation. If this program is successful, it could facilitate 
reintroduction and augmentation into areas where the species has 
declined or disappeared, to bolster the small genetic pool and small 
numbers. In 2012, researchers at the Minnesota Zoo and the University 
of Michigan initiated a genetics study of Dakota skipper and Poweshiek 
skipperling using specimens at some of the few sites where either 
species was observed in 2012, specifically a few sites in Michigan, 
Wisconsin, and Manitoba for the Poweshiek skipperling and sites in 
North Dakota, South Dakota, and Manitoba for Dakota skipper. Too few 
(one adult male) Dakota skipper were observed in Minnesota to obtain 
samples from that State in 2012. The genetics studies will help inform 
captive propagation and reintroduction efforts, which may help 
alleviate stressors associated with small and isolated populations.
    In 2011, researchers collected 32 adult Dakota skippers from a 
combination of 4 sites in South Dakota and translocated them to 
Pickerel Lake State Park, where the species was last detected in 2008 
(Skadsen 2011, pp. 7-9). The phenology of the adult flight period and 
purple coneflower blooms did not coincide, and no Dakota skippers were 
observed at the release site during subsequent visits in 2011 or 2012 
(Skadsen 2011, pp. 8-9, Skadsen 2012, p. 4). Researchers and managers 
continue to develop prairie restoration and management goals for this 
and the Hartford Beach State Park site in South Dakota (Skadsen 2011, 
p. 9; Skadsen 2012, p. 7).
    We are unaware of any conservation efforts that directly address 
the impacts of climate change to Dakota skippers or Poweshiek 
skipperlings. We are unaware of any conservation efforts that address 
the possible effects of pharmaceuticals on the Poweshiek skipperling 
and Dakota skipper.
Cumulative Effects From Factors A through E
    Many of the threats described in this finding may cumulatively or 
synergistically impact the Dakota skipper and Poweshiek skipperling 
beyond the scope of each individual threat. For example, improper 
grazing management alone may only affect portions of Dakota skipper or 
Poweshiek skipperling habitat; however, improper grazing combined with 
invasive plants, herbicide use, and drought may collectively result in 
substantial habitat loss, degradation, or fragmentation across large 
portions of the species' ranges. In turn, climate change may exacerbate 
those effects, further diminishing habitat and increasing the isolation 
of already declining and isolated populations, making them more 
susceptible to genetic drift or catastrophic events such as fire, 
flooding, and drought. Further, nonagricultural development such as 
gravel mining or housing development not only can directly destroy 
habitat, but also can increase fragmentation of habitat by increasing 
associated road development. Additionally, draining prairie fens will 
increase invasive plant and woody vegetation encroachment. Numerous 
threats are likely acting cumulatively to further increase impacts on 
the already vulnerable, small and isolated populations of Poweshiek 
skipperling and Dakota skipper.

Proposed Determinations

    Section 4 of the Act (16 U.S.C. 1533), and its implementing 
regulations at 50 CFR part 424, set forth the procedures for adding 
species to the Federal Lists of Endangered and Threatened Wildlife and 
Plants. Under section 4(a)(1) of the Act, we may list a species based 
on (A) The present or threatened destruction, modification, or 
curtailment of its habitat or range; (B) Overutilization for 
commercial, recreational, scientific, or educational purposes; (C) 
Disease or predation; (D) The inadequacy of existing regulatory 
mechanisms; or (E) Other natural or manmade factors affecting its 
continued existence. Listing actions may be warranted based on any of 
the above threat factors, singly or in combination.

Dakota skipper

    We carefully assessed the best scientific and commercial 
information available regarding the past, present, and future threats 
to the Dakota skipper. Dakota skippers are obligate residents of 
undisturbed (remnant, untilled) high-quality prairie, ranging from wet-
mesic tallgrass prairie to dry-mesic mixed-grass prairie. Native 
tallgrass prairies have been reduced by 85 to 99.9 percent of their 
former area and native mixed-grass prairies have been reduced by 71.9 
to 99 percent of their former area in North Dakota, Manitoba, and 
Saskatchewan. The Dakota skipper was once a common prairie butterfly 
widely dispersed in five states, extending from Illinois to North 
Dakota, and portions of 2 Canadian provinces. However, its range is now 
substantially reduced such that the Dakota skipper is restricted to 
small patches of fragmented native prairie remnants in portions of 
three states and two Canadian provinces. Recent survey data indicate 
that the Dakota skipper has declined to zero or to undetectable levels 
in approximately 50 percent of sites where it had been recorded 
rangewide. It is presumed extirpated from Illinois and Iowa and no 
longer occurs east of western Minnesota--an approximately 430-mi (690-
km) reduction of its range. Much of the rangewide decline in the 
species has been observed in the last few years. Since 1985, 
researchers have surveyed 10 or more sites in 27 years; the average 
positive detection rate for those years is 69 percent rangewide. Since 
2010, the percent of surveyed sites with positive detections of the 
species has dropped from 80 percent in 2010, to 42 percent in 2011, and 
to 35 percent in 2012. While these types of lows in detections have 
been observed in past years, for example, in the early 1990s, the 
numbers of individuals observed in 2012 were the lowest ever recorded, 
despite extensive survey effort. Dakota skippers currently occupy sites 
in northeastern South Dakota, North Dakota, western Minnesota, southern 
Manitoba, and southeastern Saskatchewan.
    Of the 259 historical locations, the species is presumed extirpated 
or possibly extirpated from at least 87 (34 percent) of those sites, 
and the occupancy of the species is unknown at approximately 81 (31 
percent) sites. Of the 81 sites where the occupancy is unknown, at 
least 72 sites are subject to one or more threats that have a moderate 
to high impact on those populations--these sites are distributed across 
Minnesota, North Dakota, and South Dakota. The 9 sites with unknown 
occupancy without moderate- to high-level threats are scattered in 
various counties in Minnesota and South Dakota, and the skipper is 
thought to still be present at approximately 91 (35 percent) of the 259 
historical locations, although 23 of these sites have not been surveyed 
since 2002. Of those 91 sites, at least 83 sites are subject to one or 
more threats that have a moderate to high impact on those populations, 
such as conversion to agriculture, lack of management, and small size 
and isolation. The remaining 8 sites that do not have stressors with 
moderate- to high-level impacts to populations occur in scattered 
counties in Minnesota and South Dakota. Approximately half (45 of 91) 
of the locations where the species is considered to be present are 
located on privately owned fall hayed prairies in Canada, mostly within 
3 isolated complexes, and have not been surveyed since 2007. All 45 of 
those Canadian sites have one or more stressors of moderate to high 
level of impact to

[[Page 63617]]

populations. A fair number of populations in Canada are being managed 
in a manner conducive to the conservation of the Dakota skipper and the 
threats at those sites are not immediate. However, few (4-5 sites) of 
these Canadian populations are protected (on Federal land). The 
remaining sites where the species is considered to be present are about 
equally distributed among Minnesota (14 sites), North Dakota (18 
sites), and South Dakota (14 sites). Sites with stressors with moderate 
to high level of impacts to populations occur in all three states.
    Many factors likely contributed to the Dakota skipper's decline, 
and numerous major threats, acting individually or synergistically, 
continue today (see Summary of Factors Affecting the Species). Habitat 
loss and degradation have impacted the Dakota skipper, curtailing the 
ranges of the species (see Factor A). Extensive historical conversion 
of prairie and associated habitats, nearly complete in some areas, has 
isolated many Dakota skipper populations. These small and isolated 
populations are subject to loss of genetic diversity through genetic 
drift (see Factor E) and are susceptible to a variety of stochastic 
(e.g., wildfires, droughts, and floods) and deterministic (e.g., 
overgrazing, invasive species) factors (see Factor A) that may kill all 
or a substantial proportion of a population. Although much of the 
habitat conversion occurred in the past, the effects of the dramatic 
reduction and fragmentation of habitat have persistent and ongoing 
effects on the viability of populations; furthermore, conversion of 
native prairies to agriculture or other uses is still occurring today. 
The life history of the species exacerbates the threats caused by the 
fragmentation and degradation of the species' habitat (see Factors A 
and E) as the Dakota skipper is not likely to recolonize distant sites 
due to its short adult life span, single annual flight, and limited 
dispersal ability. Therefore, the species' extirpation from a site is 
likely permanent unless it is near another site from which it can 
emigrate. Furthermore, because the larvae are located at or near the 
soil surface, they are more vulnerable to fire (Factor A), herbicides, 
pesticides, and other chemicals (see Factor E); desiccation due to 
changing climate (see Factor E); or flooding (see Factor A).
    Within the remaining native prairie patches, degradation of habitat 
quality is now the primary threat to the Dakota skipper (see Factor A). 
Of the various threats to Dakota skipper habitat, conversion, invasive 
species, secondary succession, and reduction in the diversity of native 
prairie plant communities have moderate- to high-level impacts to 
populations throughout the range of the Dakota skipper. An array of 
other factors including nonagricultural development, chemical 
contaminants, pesticides, and intensive grazing are also current and 
ongoing threats to the Dakota skipper and its habitat (see Factors A 
and E). Current and ongoing prairie management practices, such as 
indiscriminate use of herbicides or intensive grazing that reduces or 
eliminates food sources, contribute to the species' imperilment at 
sites throughout the range of the species (see Factors A and E). 
Unknown stressors may be the current threat that has the most 
significant impacts to the Dakota skipper in Iowa and Minnesota, where 
populations experienced a sudden decline to undetectable numbers in the 
most recent years (see Factor E). Based on recent data, similar 
conditions in other parts of the Dakota skipper's range, and the 
similarities in life histories between Poweshiek skipperling and Dakota 
skipper, similar declining trends are anticipated in other parts of the 
Dakota skipper's range due to unknown stressors, and may only be a few 
years behind those declines experienced by Poweshiek skipperling (see 
Factor E). Existing regulatory mechanisms vary across the species' 
ranges, and although mechanisms do exist that protect the species from 
direct take in Iowa and Minnesota, these mechanisms do not sufficiently 
mitigate threats to the species (see Factor D). Climate change may 
affect Dakota skipper, especially increased frequency of extreme 
climatic conditions such as flooding and drought, but there is limited 
information on the exact nature of impacts that these species may 
experience. Recent temperature and precipitation trends indicate that 
certain aspects of climate change may be occurring in Dakota skipper 
range now (see Factor E).
    The Act defines an endangered species as any species that is ``in 
danger of extinction throughout all or a significant portion of its 
range'' and a threatened species as any species ``that is likely to 
become endangered throughout all or a significant portion of its range 
within the foreseeable future.'' We find that the Dakota skipper is 
likely to become endangered throughout all of its range within the 
foreseeable future, based on the immediacy, severity, and scope of the 
threats described above. These threats are exacerbated by small 
population sizes, the loss of redundancy and resiliency of these 
species, and the continued inadequacy of existing protective 
regulations. A few scattered populations of Dakota skipper are doing 
relatively well, however, and are in habitats that have low or non-
immediate threats. Canada has a fair number of populations that are 
being managed in a manner conducive to the conservation of Dakota 
skipper, and the threats at those sites are not imminent. However, few 
of these populations are protected, many are vulnerable to changes in 
land use, and the sites have not been surveyed in the last 5 years. 
While a few new locations of Dakota skipper populations continue to be 
discovered in North and South Dakota, the numbers of individuals 
observed at those sites is generally low, and extirpation at previously 
known sites seems to be occurring at a faster rate than new 
discoveries. The decreasing numbers of sites with positive detections 
and the decreasing numbers of individuals observed at each site 
throughout its range, including known sites in North Dakota and South 
Dakota, is likely to continue. Therefore, on the basis of the best 
available scientific and commercial information, we propose listing the 
Dakota skipper as threatened in accordance with sections 3(6) and 
4(a)(1) of the Act.
    We find that an endangered species status is not appropriate for 
the Dakota skipper because some Dakota skipper populations still appear 
to be doing relatively well--primarily in North Dakota, South Dakota, 
Manitoba, and Saskatchewan. Canada has a fair number of populations 
that are being managed in a manner conducive to the conservation of 
Dakota skipper, and the threats at those sites are not imminent. 
Furthermore, we believe the species to be present in at least 8 sites 
that do not have documented stressors of a moderate to high level 
impact to populations, primarily in scattered counties in Minnesota and 
South Dakota. Additionally, a few new Dakota skipper sites continue to 
be discovered in suitable prairie habitat in North Dakota and South 
Dakota.
    Under the Act and our implementing regulations, a species may 
warrant listing if it is endangered or threatened throughout all or a 
significant portion of its range. Threats to the survival of the Dakota 
skipper occur throughout the species range and are not restricted to 
any particular significant portion of that range. Accordingly, our 
assessment and proposed determination applies to the Dakota skipper 
throughout its range.
Significant Portion of the Range
    In determining whether a species is threatened or endangered in a

[[Page 63618]]

significant portion of its range, we first identify any portions of the 
range of the species that warrant further consideration. The range of a 
species can theoretically be divided into portions an infinite number 
of ways. However, there is no purpose to analyzing portions of the 
range that are not reasonably likely to be both (1) Significant and (2) 
threatened or endangered. To identify only those portions that warrant 
further consideration, we determine whether substantial information 
indicates that: (1) The portions may be significant, and (2) the 
species may be in danger of extinction there or likely to become so 
within the foreseeable future. In practice, a key part of this analysis 
is whether the threats are geographically concentrated in some way. If 
the threats to the species are essentially uniform throughout its 
range, no portion is likely to warrant further consideration. Moreover, 
if any concentration of threats applies only to portions of the 
species' range that are not significant, such portions will not warrant 
further consideration.
    If we identify portions that warrant further consideration, we then 
determine whether the species is threatened or endangered in these 
portions of its range. Depending on the biology of the species, its 
range, and the threats it faces, the Service may address either the 
significance question or the status question first. Thus, if the 
Service considers significance first and determines that a portion of 
the range is not significant, the Service need not determine whether 
the species is threatened or endangered there. Likewise, if the Service 
considers status first and determines that the species is not 
threatened or endangered in a portion of its range, the Service need 
not determine if that portion is significant. However, if the Service 
determines that both a portion of the range of a species is significant 
and the species is threatened or endangered there, the Service will 
specify that portion of the range as threatened or endangered under 
section 4(c)(1) of the ESA.
    We evaluated the current range of the Dakota skipper to determine 
if potential threats for the species have any apparent geographic 
concentration. We examined potential habitat threats from effects of 
habitat loss, fragmentation, degradation, and modification from 
agriculture, development, invasive species, secondary succession, 
grazing, and haying (Factor A); overutilization for scientific or 
recreational collection (Factor B); disease and predation (Factor C); 
the inadequacy of existing regulatory mechanisms (Factor D); and the 
effects of habitat fragmentation and small population size and 
isolation, climate change, pharmaceuticals, insecticides, pesticides, 
prairie plant harvest, and unknown stressors (Factor E). As discussed 
above, although the specific threats affecting the species may be 
different at individual sites or in different parts of the Dakota 
skipper's range, on the whole threats are occurring throughout the 
species' range. The Dakota skipper is thought to still be present at 
approximately 91 sites, at least 83 of which are subject to one or more 
threats that have a moderate to high impact on those populations. On no 
portions of its range are threats significantly concentrated or 
substantially greater than in other portions of its range; therefore, 
we find that impacts to the Dakota skipper are essentially uniform 
throughout its range, indicating that the entire range warrants a 
threatened status under the Act. As discussed above, our review of the 
best available scientific and commercial information indicates that the 
Dakota skipper is not in danger of extinction (endangered) but is 
likely to become endangered within the foreseeable future (threatened) 
throughout all of its range. Therefore, we find that listing the Dakota 
skipper as a threatened species under the Act throughout its entire 
range is warranted at this time.

Poweshiek skipperling

    We carefully assessed the best scientific and commercial 
information available regarding the past, present, and future threats 
to the Poweshiek skipperling. Poweshiek skipperling are obligate 
residents of undisturbed (remnant, untilled) high-quality prairie, 
ranging from wet-mesic tallgrass prairie to dry-mesic mixed-grass 
prairie. Native tallgrass prairies have been reduced by 85 to 99.9 
percent of their former area and native mixed-grass prairies have been 
reduced by 72 to 99 percent of their former area in North Dakota, 
Manitoba, and Saskatchewan. The Poweshiek skipperling was once a common 
prairie butterfly widely dispersed in eight states, extended from 
Michigan to North Dakota, and portions of Manitoba, Canada. However, 
its range is now substantially reduced such that the Poweshiek 
skipperling is restricted to small patches of fragmented native prairie 
remnants in portions of two states and one Canadian province. The 
species is presumed extirpated from Illinois and Indiana, and the 
status of the species is unknown in four of the six states with 
relatively recent records (within the last 20 years). Recent survey 
data indicate that the Poweshiek skipperling has declined to zero or to 
undetectable levels in approximately 87 percent of sites where it has 
ever been recorded.
    A drastic decline in this species has been observed rangewide very 
recently. Between 1985 and 2003, researchers surveyed 10 or more sites 
in 7 different years (excluding new sites in the first year); the 
average positive detection rate for those years is 71 percent 
rangewide. Since 2003, the percent of surveyed sites with positive 
detections of the species has dropped to an average of 29 percent each 
year (2004-2012), with a low of 13 percent at sites surveyed in 2012. 
Despite recent substantial survey efforts in those states, the 
Poweshiek skipperling has not been recorded in Iowa since 2007, when it 
was observed at 1 site; in Minnesota since 2007, when it was observed 
at 1 site; in North Dakota since 2001, when it was observed at 1 site, 
nor in South Dakota since 2008, when it was observed at 3 sites. The 
species was not observed in North Dakota, South Dakota, or Minnesota 
during 2012 surveys, for example. Iowa sites were not surveyed in 2012. 
Poweshiek skipperling have historically been documented at 
approximately 296 sites; now we consider the species to be present at 
only 14 of those sites--one of these is considered a sub-site of a 
larger site.
    The only confirmed extant (present) populations of Poweshiek 
skipperling are currently restricted to 2 small and isolated native-
prairie remnants in Wisconsin, 10 small and isolated prairie fen 
remnants in Michigan, and a prairie complex in Manitoba. These sites 
represent only 5 percent of the total number of sites ever documented 
for the species. The numbers observed at these sites are relatively 
small (less than 100 at all but 2 sites), and all of these sites have 
at least one documented threat that have moderate to high impacts on 
those populations. The strongest population in the United States, a 
prairie fen in Michigan with relatively high and fairly consistent 
numbers observed each year (numbers observed per minute ranged from 1.2 
to 2.2 during the last 4 survey years), for instance, is under threat 
from intense development pressure. The Tallgrass Prairie Preserve site 
in Manitoba also has relatively high numbers observed each year; 
however, this site is impacted by several immediate, moderate- to high-
level threats, including the encroachment of invasive plants and woody 
vegetation, flooding, and isolation from the nearest site by hundreds 
of kilometers. In addition, recent unplanned fires in 2009 and 2011 
affected large portions of the site. Poweshiek skipperling is

[[Page 63619]]

considered to have unknown occupancy at 131 sites--throughout the range 
of the species (Iowa, Michigan, Minnesota, North Dakota, and South 
Dakota), 54 of these sites were included in the threats assessment. Of 
the 54 sites where the occupancy is unknown that had sufficient 
information to assess, at least 43 sites are subject to one or more 
threats that have a moderate to high impact on those populations. These 
sites are throughout the range of the species in Iowa, Michigan, 
Minnesota, North Dakota, and South Dakota.
Summary
    Many factors likely contributed to the Poweshiek skipperling's 
decline, and numerous major threats, acting individually or 
synergistically, continue today (see Summary of Factors Affecting the 
Species). Habitat loss and degradation have impacted the Poweshiek 
skipperling, curtailing the ranges of both species (see Factor A). 
Extensive historical conversion of prairie and associated habitats, 
nearly complete in some areas, has isolated many Poweshiek skipperling 
populations. These small and isolated populations are subject to loss 
of genetic diversity through genetic drift (see Factor E) and are 
susceptible to a variety of stochastic (e.g., wildfires, droughts, and 
floods) and deterministic (e.g., overgrazing, invasive species) factors 
(see Factor A) that may kill all or a substantial proportion of a 
population. Although much of the habitat conversion occurred in the 
past, the effects of the dramatic reduction and fragmentation of 
habitat have persistent and ongoing effects on the viability of 
populations; furthermore, conversion of native prairies to agriculture 
or other uses is still occurring today. The life history of the species 
exacerbates the threats caused by the fragmentation and degradation of 
its habitat (see Factors A and E) as Poweshiek skipperlings are not 
likely to recolonize distant sites due to their short adult life span, 
single annual flight, and limited dispersal ability. Therefore, the 
Poweshiek skipperling's extirpation from a site is likely permanent 
unless it is near another site from which it can emigrate. Furthermore, 
because the larvae are located at or near the soil surface, they are 
more vulnerable to fire (Factor A), herbicides, pesticides, and other 
chemicals (see Factor E); desiccation due to changing climate (see 
Factor E); or changes in hydrology (see Factor A).
    Within the remaining native-prairie patches, degradation of habitat 
quality is now the primary threat to the Poweshiek skipperling (see 
Factor A). Of the various threats to Poweshiek skipperling habitat, 
conversion, invasive species, secondary succession, and reduction in 
the diversity of native-prairie plant communities have moderate- to 
high-level impacts to populations throughout the range of the Poweshiek 
skipperling. An array of other factors including nonagricultural 
development, chemical contaminants, pesticides, and intensive grazing 
are also current and ongoing threats to the Poweshiek skipperling and 
its habitat (see Factors A and E). Current and ongoing prairie 
management practices, such as indiscriminate use of herbicides or 
intensive grazing that reduces or eliminates food sources, contribute 
to the species' imperilment, particularly in North Dakota, South 
Dakota, and Minnesota (see Factors A and E). Unknown stressors may be 
the current threat that has the most significant impacts to the 
Poweshiek skipperling species in Iowa, Minnesota, North Dakota, and 
South Dakota, where populations experienced a sudden decline to 
undetectable numbers in the most recent years (see Factor E). Existing 
regulatory mechanisms vary across the species' ranges, and although 
mechanisms do exist in Iowa, Michigan, Minnesota, and Wisconsin that 
protect the species from direct take, these mechanisms do not 
sufficiently mitigate threats to the Poweshiek skipperling (see Factor 
D). Climate change may affect the Poweshiek skipperling, especially 
increased frequency of extreme climatic conditions such as flooding and 
drought, but there is limited information on the exact nature of 
impacts that the species may experience. Recent temperature and 
precipitation trends indicate that certain aspects of climate change 
may be occurring in Poweshiek skipperling range now (see Factor E).
    The Act defines an endangered species as any species that is ``in 
danger of extinction throughout all or a significant portion of its 
range'' and a threatened species as any species ``that is likely to 
become endangered throughout all or a significant portion of its range 
within the foreseeable future.'' We find that the Poweshiek skipperling 
is presently in danger of extinction throughout its entire range, based 
on the immediacy, severity, and scope of the threats described above. 
These threats are exacerbated by small population sizes, the loss of 
redundancy and resiliency of these species, and the continued 
inadequacy of existing protective regulations. There are only 14 
locations where we believe the species to be present, and all of those 
sites are subject to at least one or more ongoing and immediate 
moderate- to high-level threats that have moderate- to high-level 
effects on those populations that is ongoing and immediate. Therefore, 
on the basis of the best available scientific and commercial 
information, we propose listing the Poweshiek skipperling as endangered 
in accordance with sections 3(6) and 4(a)(1) of the Act.
    We find that a threatened species status is not appropriate for the 
Poweshiek skipperling because the unknown stressors have significant 
impacts to the species throughout most of its range and have occurred 
in a short timeframe. Sharp population declines have not been detected 
at the few remaining sites where the species is still present, but all 
of these sites are currently experiencing one or more stressors that 
has moderate- to high-level impacts to populations. Based on recent 
data and similar conditions in other parts of Poweshiek skipperling 
range, similar declining trends are anticipated in other parts of the 
range of the species, and may only be a few years behind those declines 
experienced by the species in Iowa, Minnesota, North Dakota, and South 
Dakota (see Factor E). The impacts of the unknown stressors on 
populations are exacerbated by habitat curtailment and destruction and 
other factors such as the effects of small and isolated populations due 
to habitat fragmentation.
    Under the Act and our implementing regulations, a species may 
warrant listing if it is endangered or threatened throughout all or a 
significant portion of its range. The Poweshiek skipperling proposed 
for listing in this rule is highly restricted in its range, and the 
threats occur throughout its range. Therefore, we assessed the status 
of the species throughout its entire range. The threats to the survival 
of the Poweshiek skipperling occur throughout the species' range and 
are not restricted to any particular significant portion of that range. 
Accordingly, our assessment and proposed determination applies to the 
Poweshiek skipperling throughout its entire range.

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened under the Act include recognition, recovery actions, 
requirements for Federal protection, and prohibitions against certain 
practices. Recognition through listing results in public awareness and 
conservation by Federal, State, Tribal, and local agencies, private 
organizations, and individuals. The Act encourages cooperation with the 
States and requires

[[Page 63620]]

that recovery actions be carried out for all listed species. The 
protection required by Federal agencies and the prohibitions against 
certain activities are discussed, in part, below.
    The primary purpose of the Act is the conservation of endangered 
and threatened species and the ecosystems upon which they depend. The 
ultimate goal of such conservation efforts is the recovery of these 
listed species, so that they no longer need the protective measures of 
the Act. Subsection 4(f) of the Act requires the Service to develop and 
implement recovery plans for the conservation of endangered and 
threatened species. The recovery planning process involves the 
identification of actions that are necessary to halt or reverse the 
species' decline by addressing the threats to its survival and 
recovery. The goal of this process is to restore listed species to a 
point where they are secure, self-sustaining, and functioning 
components of their ecosystems.
    Recovery planning includes the development of a recovery outline 
shortly after a species is listed, preparation of a draft and final 
recovery plan, and revisions to the plan as significant new information 
becomes available. The recovery outline guides the immediate 
implementation of urgent recovery actions and describes the process to 
be used to develop a recovery plan. The recovery plan identifies site-
specific management actions that will achieve recovery of the species, 
measurable criteria that determine when a species may be downlisted or 
delisted, and methods for monitoring recovery progress. Recovery plans 
also establish a framework for agencies to coordinate their recovery 
efforts and provide estimates of the cost of implementing recovery 
tasks. Recovery teams (comprising species experts, Federal and State 
agencies, nongovernmental organizations, and stakeholders) are often 
established to develop recovery plans. When completed, the recovery 
outlines, draft recovery plans, and the final recovery plans will be 
available on our Web site (http://www.fws.gov/endangered), or from our 
Twin Cities Ecological Services Fish and Wildlife Office (see FOR 
FURTHER INFORMATION CONTACT).
    Implementation of recovery actions generally requires the 
participation of a broad range of partners, including other Federal 
agencies, States, Tribal, nongovernmental organizations, businesses, 
and private landowners. Examples of recovery actions include habitat 
restoration (e.g., restoration of native vegetation), research, captive 
propagation and reintroduction, and outreach and education. The 
recovery of many listed species cannot be accomplished solely on 
Federal lands because their range may occur primarily or solely on non-
Federal lands. To achieve recovery of these species requires 
cooperative conservation efforts on private, State, and Tribal lands.
    If these species are listed, funding for recovery actions will be 
available from a variety of sources, including Federal budgets, State 
programs, and cost-share grants for non-Federal landowners, the 
academic community, and nongovernmental organizations. In addition, 
pursuant to section 6 of the Act, the States of Iowa, Michigan, 
Minnesota, North Dakota, South Dakota, and Wisconsin would be eligible 
for Federal funds to implement management actions that promote the 
protection and recovery of the Poweshiek skipperling and Dakota 
skipper. Information on our grant programs that are available to aid 
species recovery can be found at: http://www.fws.gov/grants.
    Although the Dakota skipper and Poweshiek skipperling are only 
proposed for listing under the Act at this time, please let us know if 
you are interested in participating in recovery efforts for these 
species. Additionally, we invite you to submit any new information on 
this species whenever it becomes available and any information you may 
have for recovery planning purposes (see FOR FURTHER INFORMATION 
CONTACT).
    Section 7(a) of the Act requires Federal agencies to evaluate their 
actions with respect to any species that is proposed or listed as 
endangered or threatened and with respect to its critical habitat, if 
any is designated. Regulations implementing this interagency 
cooperation provision of the Act are codified at 50 CFR part 402. 
Section 7(a)(4) of the Act requires Federal agencies to confer with the 
Service on any action that is likely to jeopardize the continued 
existence of a species proposed for listing or result in destruction or 
adverse modification of proposed critical habitat. If a species is 
listed subsequently, section 7(a)(2) of the Act requires Federal 
agencies to ensure that activities they authorize, fund, or carry out 
are not likely to jeopardize the continued existence of the species or 
destroy or adversely modify its critical habitat. If a Federal action 
may adversely affect a listed species or its critical habitat, the 
responsible Federal agency must enter into formal consultation with the 
Service.
    Federal agency actions within the species habitat that may require 
conference or consultation or both as described in the preceding 
paragraph include, but are not limited to, management and any other 
landscape-altering activities on Federal lands such as actions within 
the jurisdiction of the Natural Resources Conservation Service; land 
management by the U.S. Forest Service; issuance of section 404 Clean 
Water Act permits by the U.S. Army Corps of Engineers; land management 
by the U.S. Fish and Wildlife Service; construction and management of 
gas pipeline, wind facilities and associated infrastructure, and power 
line rights-of-way by the Federal Energy Regulatory Commission; 
construction and maintenance of roads or highways by the Federal 
Highway Administration; and land management within branches of the 
Department of Defense (DOD). Examples of these types of actions include 
activities funded or authorized under the Farm Bill Program, 
Environmental Quality Incentives Program, Clean Water Act (33 U.S.C. 
1251 et seq.), Partners for Fish and Wildlife Program, and DOD 
construction activities related to training or other military missions.
    The Act and its implementing regulations set forth a series of 
general prohibitions and exceptions that apply to all endangered 
wildlife. The prohibitions of section 9(a)(2) of the Act, codified at 
50 CFR 17.21 for endangered wildlife, in part, make it illegal for any 
person subject to the jurisdiction of the United States to take 
(includes harass, harm, pursue, hunt, shoot, wound, kill, trap, 
capture, or collect; or to attempt any of these), import, export, ship 
in interstate commerce in the course of commercial activity, or sell or 
offer for sale in interstate or foreign commerce any listed species. 
Under the Lacey Act (18 U.S.C. 42-43; 16 U.S.C. 3371-3378), it is also 
illegal to possess, sell, deliver, carry, transport, or ship any such 
wildlife that has been taken illegally. Certain exceptions apply to 
agents of the Service and State conservation agencies.
    We may issue permits to carry out otherwise prohibited activities 
involving endangered and threatened wildlife species under certain 
circumstances. Regulations governing permits are codified at 50 CFR 
17.22 for endangered species, and at 17.32 for threatened species. With 
regard to endangered wildlife, a permit must be issued for the 
following purposes: for scientific purposes, to enhance the propagation 
or survival of the species, and for incidental take in connection with 
otherwise lawful activities.
    Our policy, as published in the Federal Register on July 1, 1994 
(59 FR 34272), is to identify to the maximum

[[Page 63621]]

extent practicable at the time a species is listed, those activities 
that would or would not constitute a violation of section 9 of the Act. 
The intent of this policy is to increase public awareness of the effect 
of a proposed listing on proposed and ongoing activities within the 
range of species proposed for listing. The following activities could 
potentially result in a violation of section 9 of the Act; this list is 
not comprehensive:
    (1) Unauthorized collecting, handling, possessing, selling, 
delivering, carrying, or transporting of the species, including import 
or export across State lines and international boundaries, except for 
properly documented antique specimens of these taxa at least 100 years 
old, as defined by section 10(h)(1) of the Act;
    (2) Introduction of nonnative species that compete with or prey 
upon the Dakota skipper and Poweshiek skipperling or their food 
sources, such as the introduction of nonnative leafy spurge, reed 
canary grass, or glossy buckthorn, to the State of Iowa, Michigan, 
Minnesota, North Dakota, South Dakota, and Wisconsin;
    (3) The unauthorized release of biological control agents that 
attack any life stage of these species, including the unauthorized use 
of herbicides, pesticides, or other chemicals in habitats in which the 
Poweshiek skipperling or Dakota skipper is known to occur;
    (4) Unauthorized modification, removal, or destruction of the 
prairie vegetation, soils, or hydrology in which the Dakota skipper and 
Poweshiek skipperling are known to occur; and
    (5) Unauthorized discharge of chemicals or fill material into any 
wetlands in which the Poweshiek skipperling or Dakota skipper are known 
to occur.
    Questions regarding whether specific activities would constitute a 
violation of section 9 of the Act should be directed to the Twin Cities 
Ecological Services Fish and Wildlife Office (see FOR FURTHER 
INFORMATION CONTACT). Requests for copies of the regulations concerning 
listed animals and general inquiries regarding prohibitions and permits 
may be addressed to the U.S. Fish and Wildlife Service, Endangered 
Species Permits, 5600 American Blvd., West, Suite 990, Bloomington, MN 
(telephone 612-713-5350; facsimile 612-713-5292).

Special Rule

    Under section 4(d) of the Act, the Secretary may publish a special 
rule that modifies the standard protections for threatened species in 
the Service's regulations at 50 CFR 17.31, which implement section 9 of 
the Act, with special measures that are determined to be necessary and 
advisable to provide for the conservation of the species. As a means to 
promote conservation efforts on behalf of the Dakota skipper, we are 
proposing a special rule for this species under section 4(d) of the 
Act. In the case of a special rule, the general regulations (50 CFR 
17.31 and 17.71) applying most prohibitions under section 9 of the Act 
to threatened species do not apply to that species, and the special 
rule contains the prohibitions necessary and appropriate to conserve 
that species.
    As discussed above, the primary factors supporting the proposed 
determination of threatened species status for the Dakota skipper are 
habitat loss and degradation of native prairies, including conversion 
of native prairie for agriculture or other development; ecological 
succession and encroachment of invasive species and woody vegetation; 
certain fire, haying, and grazing management that reduces the 
availability of certain native-prairie grasses and flowering herbaceous 
plants to Dakota skipper; some fire management; flooding; existing 
regulatory mechanisms that are inadequate to mitigate threats to the 
species; loss of genetic diversity; small size and isolation of remnant 
patches of native prairie; indiscriminate use of herbicides that 
reduces or eliminates nectar sources; climate conditions such as 
drought; and other unknown stressors.
    The Act does not specify particular prohibitions, or exceptions to 
those prohibitions, for threatened species. Instead, under section 4(d) 
of the Act, the Secretary of the Interior has the discretion to issue 
such regulations as she deems necessary and advisable to provide for 
the conservation of such species. The Secretary also has the discretion 
to prohibit by regulation with respect to any threatened species, any 
act prohibited under section 9(a)(1) of the Act. Exercising this 
discretion, the Service has developed general prohibitions (50 CFR 
17.31) and exceptions to those prohibitions (50 CFR 17.32) under the 
Act that apply to most threatened species. Alternately, for other 
threatened species, the Service develops specific prohibitions and 
exceptions that are tailored to the specific conservation needs of the 
species. In such cases, some of the prohibitions and authorizations 
under 50 CFR 17.31 and 17.32 may be appropriate for the species and 
incorporated into a special rule under section 4(d) of the Act, but the 
section 4(d) special rule will also include provisions that are 
tailored to the specific conservation needs of the threatened species 
and may be more or less restrictive than the general provisions at 50 
CFR 17.31.
    In recognition of efforts that provide for conservation and 
management of the Dakota skipper and its habitat in a manner consistent 
with the purposes of the Act, we are proposing a 4(d) special rule that 
outlines the prohibitions, and exceptions to those prohibitions, 
necessary and advisable for the conservation of the Dakota skipper. 
Economic and policy incentives are likely to continue to place pressure 
on landowners to convert native grassland from ranching to agricultural 
cropland (Doherty et al. 2013, p. 14) and a wide variety of peer-
reviewed publications and government reports have documented recent 
loss of native grassland (Congressional Research Service (CRS) 2007, p. 
5; United States Government Accountability Office (USGAO) 2007, p. 15; 
Stephens et al. 2008, p. 6; Rashford et al. 2011, p. 282; Sylvester et 
al. 2013, p. 13). Grassland loss in the western corn belt may be 
occurring at the fastest rate observed since the 1920s and 1930s and at 
a rate comparable to that of deforestation in Brazil, Malaysia, and 
Indonesia (Wright and Wimberly 2013, p. 5). Between 2006 and 2011 
destruction of native grassland was mostly concentrated in North Dakota 
and South Dakota, east of the Missouri River, an area corresponding 
closely to the range of Dakota skipper (Wright and Wimberly 2013, p. 
2).
    As with agricultural policies (Doherty et al. 2013, p. 15), the 
prohibitions against take of Dakota skipper that would become effective 
if the species is listed could interact with other factors to affect 
the rates at which native grassland is converted in the range of the 
species. Less than 20 percent of the grassland in the Prairie Pothole 
Region of the United States is permanently protected (Doherty et al. 
2013, p. 7), and the vast majority of remaining grassland is privately 
owned. The conservation of ``working landscapes'' based on ranching and 
livestock operations is frequently a priority of programs to conserve 
native grassland ecosystems in the northern Great Plains (e.g., Service 
2011, p. 5). We believe that allowing incidental take of Dakota 
skippers that may result from grazing in certain geographic areas will 
afford us more time to protect the species' habitats in these areas and 
would facilitate the coordination and partnerships needed to recover 
the species.
    In light of the socioeconomic and policy factors that are leading 
to the conversion of native prairie to

[[Page 63622]]

agricultural cropland and because there is evidence that some grazing 
practices are conducive to conservation of Dakota skipper in parts of 
its range, we determine that it is necessary and advisable to allow 
take of the species caused by certain ranching activities. Whereas 
conversion to cropland would kill any Dakota skipper larvae present and 
destroy any habitat value for the species into the foreseeable future, 
some habitats can remain suitable for Dakota skipper when grazed (Dana 
1991, p. 54; Schlicht 1997, p. 5; Skadsen 1997, pp. 24-29). In 
addition, grazing is one of the primary treatments for controlling 
smooth brome and enhancing native plant diversity in prairies that have 
been invaded by this nonnative grass species (Service 2006, p. 2; Smart 
et al. in prep.). However, some grazing practices are adverse for 
Dakota skipper; therefore, we will work with private landowners, public 
land managers, state and Federal conservation agencies, and 
nongovernmental organizations to identify, refine, and implement 
grazing practices that are conducive to the species' conservation.

Provisions of the Proposed Special Rule for Dakota Skipper

    Section 4(d) of the Act states that ``the Secretary shall issue 
such regulations as [s]he deems necessary and advisable to provide for 
the conservation'' of species listed as a threatened species. 
Conservation is defined in the Act to mean ``to use and the use of all 
methods and procedures which are necessary to bring any endangered 
species or threatened species to the point at which the measures 
provided pursuant to [the Act] are no longer necessary.'' Additionally, 
section 4(d) states that the Secretary ``may by regulation prohibit 
with respect to any threatened species any act prohibited under section 
9(a)(1).''
    The courts have recognized the extent of the Secretary's discretion 
under this standard to develop rules that are appropriate for the 
conservation of a species. For example, the Secretary may find that it 
is necessary and advisable not to include a taking prohibition, or to 
include a limited taking prohibition. See Alsea Valley Alliance v. 
Lautenbacher, 2007 U.S. Dist. Lexis 60203 (D. Or. 2007); Washington 
Environmental Council v. National Marine Fisheries Service, and 2002 
U.S. Dist. Lexis 5432 (W.D. Wash. 2002). In addition, as affirmed in 
State of Louisiana v. Verity, 853 F.2d 322 (5th Cir. 1988), the rule 
need not address all the threats to the species. As noted by Congress 
when the Act was initially enacted, ``once an animal is on the 
threatened list, the Secretary has an almost infinite number of options 
available to him with regard to the permitted activities for those 
species. [S]he may, for example, permit taking, but not importation of 
such species,'' or [s]he may choose to forbid both taking and 
importation but allow the transportation of such species, as long as 
the measures will ``serve to conserve, protect, or restore the species 
concerned in accordance with the purposes of the Act'' (H.R. Rep. No. 
412, 93rd Cong., 1st Sess. 1973).
    Section 9 prohibitions make it illegal for any person subject to 
the jurisdiction of the United States to take (including harass, harm, 
pursue, shoot, wound, kill, trap, capture, or collect; or attempt any 
of these), import or export, ship in interstate commerce in the course 
of commercial activity, or sell or offer for sale in interstate or 
foreign commerce any wildlife species listed as an endangered species, 
without written authorization. It also is illegal under section 9(a)(1) 
of the Act to possess, sell, deliver, carry, transport, or ship any 
such wildlife that is taken illegally. Prohibited actions consistent 
with section 9 of the Act are outlined for threatened species in 50 CFR 
17.31(a) and (b). This proposed 4(d) special rule proposes that all 
prohibitions in 50 CFR 17.31(a) and (b) will apply to the Dakota 
skipper except in the specific instances as outlined below. The 
proposed 4(d) special rule will not remove or alter in any way the 
consultation requirements under section 7 of the Act.

Routine Livestock Operations and Maintenance of Recreational Trails

    First, the Service proposes that incidental take that is caused by 
the routine livestock ranching and recreational trail maintenance 
activities described below and that are implemented on private, state, 
and tribal lands will not be prohibited, as long as those activities 
are otherwise legal and conducted in accordance with applicable State, 
Federal, tribal, and local laws and regulations. For the purposes of 
this rule, routine livestock ranching and recreational trail 
maintenance activities include:
    (1) Fence Construction and Maintenance: Fences are an essential 
tool for livestock and ranch management. In addition, the strategic 
distribution of fencing is also necessary to implement multi-cell 
rotational grazing systems, which may be necessary to improve grazing 
management and conserve Dakota skipper habitat.
    (2) Livestock Gathering and Management: The installation and 
maintenance of corrals, loading chutes, and other livestock working 
facilities that are critical to ranch operations. These activities may 
be carried out with only minimal impacts to Dakota skipper if carefully 
sited with respect to the location and distribution of important Dakota 
skipper habitat.
    (3) Development and Maintenance of Livestock Watering Facilities: 
Without a suitable water source in a pasture, livestock ranching is 
impossible. The proper distribution of livestock watering sources is 
also a prerequisite to implementing improved grazing management via the 
use of multi-cell rotational grazing systems that may be necessary to 
conserve Dakota skipper on grazed sites. This activity includes both 
the initial development of water sources and their maintenance. Dugout 
ponds, for example, typically require a cleanout after 15 to 20 years.
    (4) Noxious Weed Control: State and county laws require landowners 
to control noxious weeds on their property, and the timing of control 
actions is usually dependent on phenology (growth stage) of the weed 
species. Control of noxious weeds may also be important to protect 
Dakota skipper habitat because native plant diversity may decline when 
nonnative plant species invade tallgrass prairie (Boettcher et al. 
1993, p. 35). Broadcast application of herbicides, however, may result 
in significant deterioration of habitat quality for Dakota skippers 
(Smart et al. 2011, p. 184). Therefore, incidental take of Dakota 
skipper that may result from spot-spraying of herbicides would be 
allowed.
    (5) Haying: Stock cows need to be maintained through the non-
growing season; thus, haying is a critical component of ranch activity. 
Dakota skippers occur on several native hayland sites--sites where the 
native-prairie vegetation is mowed for hay. For the purposes of this 
rule, native hayland does not include lands that had previously been 
plowed and were then replanted to native or nonnative vegetation. 
Native haylands are typically cut in August, after the needlegrass 
(Hesperostipa spp. or Nassella viridula, or both) awns drop. Incidental 
take of Dakota skippers that occurs as a result of haying no earlier 
than July 16 (after July 15) is allowed. Dakota skippers are unlikely 
to occur in replanted grasslands (grasslands replanted on formerly 
plowed or cultivated lands) or in tame hayland (grassland comprised 
primarily of nonnative grass species, such as smooth brome (Bromus 
inermis inermis)). Therefore, mowing before July 16 is allowed on 
replanted and tame grasslands.

[[Page 63623]]

    (6) Mowing Rights of Way and Recreational Trails: Section line 
rights of way and some recreational trails need to be mowed several 
times during the growing season to ensure that winter snow will not 
catch and block vehicle access and that they are suitable for hiking 
and other intended recreational activities, respectively. These areas 
typically comprise disturbed soil that has been contoured for a roadway 
and are likely to contain only small proportions of Dakota skipper 
habitat at any affected site. Therefore, impacts to Dakota skipper 
populations are likely to be minimal, and any incidental take that is 
caused by mowing of section line rights of way and recreational trails 
is allowed.
    (7) Livestock (e.g., cattle or bison) grazing, except on lands 
where Dakota skipper occurs in the following states and counties: 
Minnesota--Kittson; North Dakota--Eddy, McHenry, Richland, Rolette, 
Sargent, and Stutsman. In those counties Dakota skippers inhabit 
relatively flat and moist habitats where they may be especially 
sensitive to effects of grazing (Royer et al. 2008, pp. 11, 16), 
including trampling, soil compaction, and loss of important nectar 
sources; haying conducted after the Dakota skipper flight period is the 
predominant management on sites inhabited by the species in these 
counties. In all other states and counties, incidental take of Dakota 
skippers that may result from grazing is allowed under this rule.
    In the drier and hillier habitats that the species inhabits outside 
of the counties listed above, grazing may benefit Dakota skipper 
depending on its intensity. Moreover, in contrast to the permanent 
habitat destruction caused by plowing, mining, and certain other 
activities, native plant diversity in tallgrass prairie may recover 
from overgrazing if it has not been too severe or prolonged. In eastern 
South Dakota, Dakota skipper populations were deemed secure at some 
sites managed with rotational grazing that was sufficiently light to 
maintain native plant species diversity (Skadsen 1997, pp. 24-29) and 
grazing may also benefit Dakota skippers by reducing the area dominated 
by tall native grasses, such as big bluestem and Indiangrass (Dana 
1991). Nevertheless, grazing can also have significant deleterious 
effects on Dakota skipper; for example, a strong population of the 
species at a grazed site in South Dakota was extirpated after a change 
in ownership resulted in significant overgrazing (Skadsen 2006, p. 5). 
Therefore, we intend to cooperate with ranchers and our state and 
tribal conservation partners to identify, test, and implement grazing 
practices that effectively conserve Dakota skipper populations. By 
allowing grazing in the geographic areas where the Dakota skipper 
primarily inhabits dry-mesic prairie, we may slow the loss of native 
prairie conversion for crop production and also maintain partnerships 
that are critical for conserving the species.
    In the counties where this rule would not allow take caused by 
livestock grazing, Dakota skipper almost exclusively inhabits 
relatively flat and moist prairie habitats that are mowed for hay. 
These habitats, referred to as calcareous or ``alkaline prairies'' by 
McCabe (1979, p. 17; 1981, p. 179); ``wet mesic'' by Royer and Marrone 
(1992, p. 21); and, ``Type A'' by Royer et al. (2008, p. 14), are 
distinguished from other Dakota skipper habitats by relatively flat 
topography and certain plant community and soil characteristics (Lenz 
1999, pp. 5-7; Royer et al. 2008, pp. 14-15). Dakota skippers appear to 
be generally absent from this type of habitat in North Dakota when it 
is grazed due to a shift away from a plant community that is suitable 
for the species (McCabe 1979, p. 17; 1981, p. 179). The shift in plant 
community composition and adverse effects to Dakota skipper populations 
may occur rapidly (McCabe 1981, p. 179; Royer and Royer 1998, p. 23). 
The conversion of similar habitats in Manitoba from haying to grazing 
may be a major threat to the Dakota skipper there (Webster 2007, pp. i-
ii, 6). In contrast, limited or ``light rotational grazing'' of 
habitats on steep dry-mesic slopes in Saskatchewan may not conflict 
with Dakota skipper conservation (Webster 2007, p. ii).
    The reduced vulnerability of habitats on dry-mesic slopes to the 
effects of grazing may be due, in part, to the tendency for grazing 
pressure to be lighter in sloped areas. The steepness of habitats 
occupied by Dakota skipper in Saskatchewan, for example, limits their 
use for grazing (Webster 2007, p. ii). Steep slopes may also play a 
role in reducing the adverse effects of grazing at some sites in South 
Dakota--at one grazed site inhabited by Dakota skipper, for example, 
habitat on steep slopes was ``in good condition'', whereas ``lesser 
slopes'' were ``moderately grazed'' and some areas were ``overgrazed'' 
(Skadsen 1999, p. 29).
    The best available information indicates that in the counties where 
this rule would not allow take caused by livestock grazing the species 
may be extant at 19 sites and only 1 of those is currently grazed. The 
single grazed site is in McHenry County, North Dakota, and is owned by 
the State of North Dakota. The habitat at the site is described as 
``marginal'' for Dakota skipper and there ``has never been a strong'' 
presence of the species, based on surveys of the site conducted since 
about 1991 (Royer 2013, pers. comm.). Since Dakota skipper was recorded 
there in 1998, only one survey has been conducted--in 2012 (Royer and 
Royer 1998, p. 9; Royer and Royer 2012, p. 3). No Dakota skippers were 
found there during two surveys in 2012, although they were present at a 
hayed site across the road (Royer and Royer 2012, p. 42). At three 
other sites in the counties where this rule would not allow take caused 
by grazing, grazing was likely the primary factor that led to the 
species' extirpation. At each of these sites grazing was described as 
``heavy'' or ``substantial'', the habitat was degraded, and important 
nectar sources were lacking or depleted (Royer and Royer 2012, pp. 9, 
12, 27).
    The lack of any examples of sites where strong populations of 
Dakota skippers occur in concert with grazing indicates to us that it 
would not be advisable at this time to allow take caused by grazing in 
the counties listed above--Kittson County, Minnesota, and Eddy, 
McHenry, Richland, Rolette, Sargent, and Stutsman Counties in North 
Dakota. In these counties, Dakota skipper primarily inhabits wet-mesic 
prairie habitats that support plant communities that are distinct from 
those that occur on dry-mesic prairie elsewhere in the species' range.
    The Service is committed to working with private landowners, public 
land managers, conservation agencies, nongovernmental organizations, 
and the scientific community to determine whether any grazing of Dakota 
skipper habitat in any of the counties may be conducted in a manner 
that is conducive to the species' conservation. We are seeking public 
comments on this topic. In the meantime, the continuation of hay 
production as the primary use of these habitats--with mowing occurring 
no earlier than July 16--is the most compatible land use activity for 
the Dakota skipper and would contribute substantially to the 
conservation of the species.

Peer Review

    In accordance with our joint policy on peer review published in the 
Federal Register on July 1, 1994 (59 FR 34270), we will seek the expert 
opinions of at least three appropriate and independent specialists 
regarding this proposed rule. We have invited these peer reviewers to 
comment during this public comment period on our specific assumptions 
and conclusions in this proposed rule.

[[Page 63624]]

    We will consider all comments and information received during this 
comment period on this proposed rule during our preparation of a final 
determination. Accordingly, the final decision may differ from this 
proposal.

Public Hearings and Informational Meetings

    Section 4(b)(5) of the Act provides for one or more public hearings 
on this proposal, if requested. Requests must be received within 45 
days after the date of publication of this proposed rule in the Federal 
Register. Such requests must be sent to the address shown in FOR 
FURTHER INFORMATION CONTACT. We will schedule public hearings on this 
proposal, if any are requested, and announce the dates, times, and 
places of those hearings, as well as how to obtain reasonable 
accommodations, in the Federal Register and local newspapers at least 
15 days before the hearing.
    We have scheduled informational meetings regarding the proposed 
rule in the locations specified in ADDRESSES. Any interested 
individuals or potentially affected parties seeking additional 
information on the public informational meetings should contact the 
Twin Cities Ecological Services Office (See FOR FURTHER INFORMATION 
CONTACT). The U.S. Fish and Wildlife Service is committed to providing 
access to this event for all participants. Please direct all requests 
for interpreters, closed captioning, or other accommodation to the Twin 
Cities Ecological Services Office (See FOR FURTHER INFORMATION 
CONTACT).

Required Determinations

Clarity of the Rule

    We are required by Executive Orders 12866 and 12988 and by the 
Presidential Memorandum of June 1, 1998, to write all rules in plain 
language. This means that each rule we publish must:
    (1) Be logically organized;
    (2) Use the active voice to address readers directly;
    (3) Use clear language rather than jargon;
    (4) Be divided into short sections and sentences; and
    (5) Use lists and tables wherever possible.
    If you feel that we have not met these requirements, send us 
comments by one of the methods listed above in ADDRESSES. To better 
help us revise the rule, your comments should be as specific as 
possible. For example, you should tell us the numbers of the sections 
or paragraphs that are unclearly written, which sections or sentences 
are too long, the sections where you feel lists or tables would be 
useful, etc.

National Environmental Policy Act (42 U.S.C. 4321 et seq.)

    We have determined that environmental assessments and environmental 
impact statements, as defined under the authority of the National 
Environmental Policy Act (NEPA; 42 U.S.C. 4321 et seq.), need not be 
prepared in connection with listing a species as an endangered or 
threatened species under the Endangered Species Act. We published a 
notice outlining our reasons for this determination in the Federal 
Register on October 25, 1983 (48 FR 49244).

Government-to-Government Relationship With Tribes

    In accordance with the President's memorandum of April 29, 1994 
(Government-to-Government Relations with Native American Tribal 
Governments; 59 FR 22951), Executive Order 13175 (Consultation and 
Coordination With Indian Tribal Governments), and the Department of the 
Interior's manual at 512 DM 2, we readily acknowledge our 
responsibility to communicate meaningfully with recognized Federal 
Tribes on a government-to-government basis. In accordance with 
Secretarial Order 3206 of June 5, 1997 (American Indian Tribal Rights, 
Federal-Tribal Trust Responsibilities, and the Endangered Species Act), 
we readily acknowledge our responsibilities to work directly with 
tribes in developing programs for healthy ecosystems, to acknowledge 
that tribal lands are not subject to the same controls as Federal 
public lands, to remain sensitive to Indian culture, and to make 
information available to tribes.

References Cited

    A complete list of references cited in this rulemaking is available 
on the Internet at http://www.regulations.gov and upon request from the 
Field Supervisor, Twin Cities Field Office (see FOR FURTHER INFORMATION 
CONTACT).

Authors

    The primary authors of this package are the staff members of the 
Twin Cities Field Office.

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, and Transportation.

Proposed Regulation Promulgation

    Accordingly, we propose to amend part 17, subchapter B of chapter 
I, title 50 of the Code of Federal Regulations, as set forth below:

PART 17--[AMENDED]

0
1. The authority citation for part 17 continues to read as follows:

    Authority: 16 U.S.C. 1361-1407; 1531-1544; 4201-4245, unless 
otherwise noted.

0
2. In Sec.  17.11(h), add entries for ``Skipper, Dakota'' and 
``Skipperling, Poweshiek'' to the List of Endangered and Threatened 
Wildlife in alphabetical order under ``Insects'' to read as set forth 
below:


Sec.  17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
                        Species                                                    Vertebrate
--------------------------------------------------------                        population where                                  Critical     Special
                                                            Historic range       endangered or         Status      When listed    habitat       rules
           Common name                Scientific name                              threatened
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                      * * * * * * *
             Insects
 
                                                                      * * * * * * *
Skipper, Dakota..................  Hesperia dacotae....  U.S.A. (IL, IA, MN,  NA.................  T               ...........           NA     17.47(b)
                                                          ND, SD); Canada
                                                          (Manitoba,
                                                          Saskatchewan).
 

[[Page 63625]]

 
                                                                      * * * * * * *
Skipperling, Poweshiek...........  Oarisma poweshiek...  U.S.A. (IL, IA, IN,  NA.................  E               ...........           NA           NA
                                                          MI, MN, WI, ND,
                                                          SD); Canada
                                                          (Manitoba).
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------

0
3. Amend Sec.  17.47 by adding paragraph (b) to read as follows:


Sec.  17.47  Special rules--insects.

* * * * *
    (b) Dakota skipper (Hesperia dacotae).
    (1) Which populations of the Dakota skipper are covered by this 
special rule? This rule covers the distribution of Dakota skipper in 
the United States.
    (2) Prohibitions. Except as noted in paragraph (b)(3) of this 
section, all prohibitions and provisions of Sec. Sec.  17.31 and 17.32 
apply to the Dakota skipper.
    (3) Exemptions from prohibitions. Incidental take of Dakota skipper 
will not be a violation of section 9 of the Act if it occurs as a 
result of:
    (i) Recreational trail maintenance activities;
    (ii) Mowing of section line rights of way; and
    (iii) Routine livestock ranching activities that are conducted in 
accordance with applicable State, Federal, tribal, and local laws and 
regulations. For the purposes of this rule, routine livestock ranching 
activities include:
    (A) Fence construction and maintenance.
    (B) Activities pertaining to livestock gathering and management, 
such as the installation and maintenance of corrals, loading chutes, 
and other livestock working facilities.
    (C) Development and maintenance of livestock watering facilities.
    (D) Spot-spraying of herbicides for noxious weed control (Broadcast 
application of herbicides is not allowed.).
    (E) Haying, as set forth in this paragraph (b)(3)(i)(E):
    (1) In native haylands, which are typically cut in August after the 
needlegrass (Hesperostipa spp. or Nassella viridula) awns drop, haying 
after July 15 is allowed.
    (2) In replanted grasslands (grasslands replanted on formerly 
plowed or cultivated lands) or in tame haylands (grasslands comprising 
primarily nonnative grass species, such as smooth brome (Bromus inermis 
inermis)), mowing may occur at any time.
    (F) Grazing of cattle, bison, or horses, except in Kittson County, 
Minnesota, and Eddy, McHenry, Richland, Rolette, Sargent, and Stutsman 
Counties, North Dakota, where the Dakota skipper inhabits areas that 
may be especially sensitive to the effects of grazing by these types of 
livestock.
* * * * *

    Dated: September 23, 2013.
Rowan W. Gould,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 2013-24175 Filed 10-23-13; 8:45 am]
BILLING CODE 4310-55-P