[Federal Register Volume 75, Number 64 (Monday, April 5, 2010)]
[Rules and Regulations]
[Pages 17062-17070]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-7547]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R8-ES-2010-0016]
[MO 92210-0-0008-B2]


Endangered and Threatened Wildlife and Plants; 90-Day Finding on 
a Petition To List Thorne's Hairstreak Butterfly as or Endangered

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of petition finding and initiation of status review.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a 
90-day finding on a petition to list Thorne's hairstreak butterfly 
(Callophrys [Mitoura] grynea thornei or Callophrys [Mitoura] thornei) 
as endangered under the Endangered Species Act of 1973, as amended and 
to designate critical habitat. We find the petition and information 
currently available in our records presents substantial scientific or 
commercial information indicating that listing Thorne's hairstreak 
butterfly may be warranted. Therefore, with the publication of this 
notice, we are initiating a status review to determine if the 
petitioned action is warranted. To ensure that the status review is 
comprehensive, we are requesting scientific and commercial data and 
other information regarding this species. Based on the status review, 
we will issue a 12-month finding on the petition, which will address 
whether the petitioned action is warranted, as provided in section 
4(b)(3)(B) of the Act.

DATES: To allow us adequate time to conduct this review, we request 
that we receive information on or before June 4, 2010. After this date, 
you must submit information directly to the Carlsbad Fish and Wildlife 
Office (see FOR FURTHER INFORMATION CONTACT section below). Please note 
that we may not be able to address or incorporate information that we 
receive after the above requested date.

ADDRESSES: You may submit comments by one of the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov. 
Search for Docket No. FWS-R8-ES-2010-0016 and then follow the 
instructions for submitting comments.
     U.S. mail or hand-delivery: Public Comments Processing, 
Attn: FWS-R8-ES-2010-0016; Division of Policy and Directives 
Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax Drive, 
Suite 222; Arlington, VA 22203.
    We will post all information received on http://www.regulations.gov. This generally means that we will post any 
personal information you provide us (see the Information Requested 
section below for more details).

FOR FURTHER INFORMATION CONTACT: Jim Bartel, Field Supervisor, Carlsbad 
Fish and Wildlife Office, U.S. Fish and Wildlife Service, 6010 Hidden 
Valley Road, Suite 101, Carlsbad, CA 92011; by telephone at 760-431-
9440; or by facsimile to 760-431-9624. Persons who use a 
telecommunications device for the deaf (TDD) may call the Federal 
Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Information Requested

    When we make a finding that a petition presents substantial 
information indicating that listing a species may be warranted, we are 
required to promptly review the status of the species (status review). 
For the status review to be complete and based on the best available 
scientific and commercial information, we request information on the 
Thorne's hairstreak butterfly from governmental agencies, Native 
American Tribes, the scientific community, industry, and any other 
interested parties. We seek information on:
    (1) The species' biology, range, and population trends, including:
    (a) Habitat requirements for feeding, breeding, and sheltering;
    (b) Genetics and taxonomy;

[[Page 17063]]

    (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 and/or 
its habitat or both.
    (2) The factors that are the basis for making a listing/delisting/
downlisting determination for a species under section 4(a) of the 
Endangered Species Act of 1973, as amended (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) The historical and current status and distribution of the 
Thorne's hairstreak butterfly, its biology and ecology, and ongoing 
conservation measures for the species and its habitat in the United 
States and Mexico.
    (4) Information on management programs for the conservation of the 
Thorne's hairstreak butterfly.
    Please include sufficient information with your submission (such as 
full references) to allow us to verify any scientific or commercial 
information you include.
    If, after the status review, we determine that listing the Thorne's 
hairstreak butterfly is warranted, we intend to propose critical 
habitat (see definition in section 3(5)(A) of the Act), in accordance 
with section 4 of the Act, to the maximum extent prudent and 
determinable at the time we propose to list the species. Therefore, 
within the geographical range currently occupied by the Thorne's 
hairstreak butterfly, we request data and information on:
    (1) What may constitute ``physical or biological features essential 
to the conservation of the species,''
    (2) Where these features are currently found, and
     (3) Whether any of these features may require special management 
considerations or protection.
    In addition, we request data and information on ``specific areas 
outside the geographical area occupied by the species'' that are 
``essential to the conservation of the species.'' Please provide 
specific comments and information as to what, if any, critical habitat 
you think we should propose for designation if the species is proposed 
for listing, and why such habitat meets the requirements of section 4 
of the Act.
    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. Section 
4(b)(1)(A) of the Act directs that determinations as to whether any 
species is an endangered or threatened species must be made ``solely on 
the basis of the best scientific and commercial data available.''
    You may submit your information concerning this status review by 
one of the methods listed 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 
website. If you submit a hardcopy that includes personal identifying 
information, you may request at the top of your document that we 
withhold this personal identifying 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.
    Information and supporting documentation that we received and used 
in preparing this finding, will be available for you to review at 
http://www.regulations.gov, or you may make an appointment during 
normal business hours at the U.S. Fish and Wildlife Service, Carlsbad 
Fish and Wildlife Office (see FOR FURTHER INFORMATION CONTACT).

Background

    Section 4(b)(3)(A) of the Act requires that we make a finding on 
whether a petition to list, delist, or reclassify a species presents 
substantial scientific or commercial information indicating that the 
petitioned action may be warranted. We are to base this finding on 
information provided in the petition, supporting information submitted 
with the petition, and information otherwise available in our files. To 
the maximum extent practicable, we are to make this finding within 90 
days of our receipt of the petition and publish our notice of the 
finding promptly in the Federal Register.
    Our standard for substantial scientific or commercial information 
within the Code of Federal Regulations (CFR) with regard to a 90-day 
petition finding is ``that amount of information that would lead a 
reasonable person to believe that the measure proposed in the petition 
may be warranted'' (50 CFR 424.14(b)). If we find that substantial 
scientific or commercial information was presented, we are required to 
promptly review the status of the species, which is subsequently 
summarized in our 12-month finding.

Previous Federal Actions

    On August 8, 2006, we published 90-day findings for both the 
Thorne's hairstreak and the Hermes copper butterfly in the Federal 
Register. The findings concluded that the petitions and information in 
our files did not present substantial scientific or commercial 
information indicating that listing Thorne's hairstreak (71 FR 44980) 
or Hermes copper butterflies (71 FR 44966) was warranted. (For a 
detailed history of Federal actions involving the Thorne's hairstreak 
butterfly prior to the 2006 90-day finding, please see the August 8, 
2006 Federal Register Notice (71 FR 44980)). On March 17, 2009, CBD and 
David Hogan filed a complaint for declaratory and injunctive relief 
challenging the Service's decision not to list the Thorne's hairstreak 
butterfly and the Hermes copper butterfly as threatened or endangered 
under the Act. In a settlement agreement dated October 23, 2009 (Case 
No. 09-0533 S.D. Cal.), the Service agreed to submit new 90-day 
petition findings to the Federal Register by April 2, 2010, for the 
Thorne's hairstreak butterfly, and by May 13, 2010, for the Hermes 
copper butterfly. As a part of the settlement agreement, we agreed to 
evaluate the October 25, 2004 petition filed by David Hogan and CBD, 
supporting information submitted with the petition, and information 
available in the Service's files, including information that has become 
available since the publication of the negative 90-day findings on 
August 8, 2006. If the 90-day findings determine that listing may be 
warranted, we agreed to submit a 12-month finding to the Federal 
Register by March 4, 2011, for the Thorne's hairstreak butterfly, and 
by April 15, 2011, for the Hermes copper butterfly.
    This notice constitutes our 90-day finding on the petition to list 
Thorne's hairstreak butterfly under section 4(b)(1)(A) of the Act. We 
will publish the 90-day finding on the petition to list Hermes copper 
butterfly in a future Federal Register document.

Species Information

Taxonomy

    Thorne's hairstreak butterfly was first described by John Brown 
(1983) based on a specimen collected by Fred Thorne in 1972. In this 
description, Brown placed the new species in the Lycaenidae family with 
the scientific name Mitoura thornei. The taxonomic ranking and 
placement of Mitoura

[[Page 17064]]

thornei was evaluated in 1999 by the Committee on Scientific Names of 
North American Butterflies and subsequently changed to a subspecies of 
Callophrys gryneus (Faulkner and Klein 2005, p. 31). As a result of 
this change, the species was renamed as Callophrys gryneus thornei. To 
validate this nomenclature change, the Service contracted Dr. Richard 
W. Van Bursick (2004) to review the Thorne's hairstreak butterfly's 
taxonomic status. This review concurred with the Committee on 
Scientific Names of North American Butterflies' (1999) decision and the 
Service currently recognizes Thorne's hairstreak butterfly as the 
subspecies Callophrys gryneus thornei. There has been significant 
discussion and disagreement by species experts on the taxonomic 
placement of this butterfly species (Faulkner and Klein 2005, p. 31), 
resulting in our receipt of new information from a species expert that 
disagrees with the previously cited taxonomic classification of 
Thorne's hairstreak butterfly (Klein 2009, pers. comm.). Due to the 
discrepancy over the taxonomic nomenclature of this species, we plan to 
re-evaluate Van Buskirk's (2004) review of taxonomic status for 
Thorne's hairstreak butterfly and will publish the results in the 12-
month finding.
    The host plant for Thorne's hairstreak butterfly larvae is 
Hesperocyparis forbesii (Tecate cypress). This species had been known 
for some time in the literature as Cupressus forbesii. Cupressus 
forbesii, and the rest of the Western Hemisphere taxa of Cupressus have 
been segregated as Hesperocyparis based on phylogenetic comparisons 
that support morphological evidence (Adams et al. 2009, pp. 160-185). 
Hesperocyparis forbesii will be the name recognized for the species in 
the upcoming revision of the Jepson Manual of the Flora of California. 
This name will used throughout this and all future documents referring 
to this species.

Species Status and Distribution

    Thorne's hairstreak butterfly is endemic to San Diego County, and 
more specifically found exclusively in the Otay Mountain area (Faulkner 
and Klein 2005, p. 31). It is dependent on its larval host plant, 
Hesperocyparis forbesii, to complete its lifecycle (Brown 1983), and is 
the only plant known on which Thorne's hairstreak butterflies lay their 
eggs. Adults lay their eggs on H. forbesii stems where the eggs mature, 
subsequently hatch, and larvae feed until pupation occurs in the duff 
and leaf litter at the base of the plant. Thorne's hairstreak 
butterflies have two hatching or flight periods per year (termed 
bivoltine): the first flight period occurs in late March to early April 
and the second flight period occurs in September, which is thought to 
be dependent on the presence of summer rains (Faulkner and Klein 2005, 
p. 32). Adult Thorne's hairstreak butterflies are known to feed 
throughout the chaparral ecosystem on the nectar of Eriogonum 
fasciculatum (California buckwheat), Ceanothus tomentosus (Ramona 
lilac), and Lotus scoparius (deerweed) in the vicinity of stands of H. 
forbesii (Faulkner and Klein 2005, p. 33). We received new information 
as a result of a recent study indicating that Asclepias fascicularis 
(narrowleaf milkweed) is also used as an adult nectar source by 
Thorne's hairstreak butterfly throughout the species' range (Lucas 
2009, pers. comm.). Confirmed observations of Thorne's hairstreak 
butterfly have been historically reported throughout the Otay Mountain 
area and have been repeatedly reported from O'Neill Canyon, Little 
Cedar Canyon, and Cedar Canyon, all of which are within the Otay 
Mountain wilderness (Betzler et al. 2003, pp. 13-14; Martin 2004, pers. 
comm.; Faulkner and Klein 2005, p. 32; Lucas 2009, unpublished data).

Habitat

    Hesperocyparis forbesii, a species generally associated with 
chaparral, is a serotinous- (not opening on maturity) or closed-coned 
conifer. Typically,its cones do not open and disperse seed until after 
fire, which nearly always results in the death of the parent tree 
(Zedler 1977, p. 456). Cone production for H. forbesii begins around 10 
years of age (Zedler 1977, p. 456). While Zedler (1977, p. 456) 
asserted that maximum production per tree is not achieved until 
individuals reach approximately 50 years of age, Dunn (1986, p. 371) 
concluded that a maximum level of cones per square meter of the cypress 
stand is attained at about 35 to 40 years of age. Hesperocyparis 
forbesii's historical distribution on Otay Mountain was known to be 
approximately 7,500 acres (ac) (3,035 hectares (ha)) (CNDDB 2003).
    Hesperocyparis forbesii persistence may be impacted by wildfires in 
the Otay Mountain area. Throughout the past 35 years, the Otay Mountain 
area has been subject to multiple fires of various levels of severity 
(Zedler 1977, p. 456; Keeley and Fotheringham 2003, pp. 242-243). 
Service GIS files indicate that the 2003 Otay/Mine fire footprint 
completely covered the known distribution of H. forbesii in the Otay 
Mountain area followed by the 2007 Harris fire that burned a 
substantial portion of this area again. Some researchers also 
postulated that an increase in frequency of fires in the area may: (1) 
Result in changing vegetation structure or type conversion (Zedler 
1977, p. 457; Zedler et al. 1983, p. 817; Keeley and Fotheringham 2003, 
pp. 243-244), and (2) lead to significant declines or possible 
extinction of H. forbesii in the Otay Mountain area because adult H. 
forbesii will not have the opportunity to reach an age where 
reproductive output is high enough to sustain the population (Zedler 
1977, p. 457). While Dunn (1985, p. 5) concluded that the Otay 
population was not in ``immediate danger,'' he noted that ``an 
increasing threat of development and its effects on fire frequency'' 
affected this area. Nonetheless, de Gouvenain and Ansary (2006, pp. 
451-452) reported that the Otay Mountain, Tecate Peak, and Guatay 
populations of H. forbesii ``appeared to be stable or potentially 
increasing'' (i.e., the rate of population increase or [lgr] > 1).'' 
However, Markovchick-Nicholls (2007, p. 50) concluded that ``[m]odel 
results utilizing available data and incorporating natural variation 
suggest that Tecate cypress [in the United States] will decline under 
most fire regime scenarios over the long-term, but that this trend may 
be difficult to detect in the short-term.'' Results from a recent study 
on the abundance of H. forbesii stands (individuals 3.3 ft (1 m) or 
higher) indicate there are approximately 454 ac (184 ha) located 
throughout the Otay Mountain area (Lucas 2009, unpublished data) and 
other burned areas contain small (less than 3.3 ft (1 m)) individuals 
that have sprouted since the 2003 and 2007 fires (Winchell, pers. obs. 
2009). These surveys corroborated historical data (Betzler et al. 2003) 
that the oldest stands occur in Little Cedar Canyon and the largest 
stands occur in O'Neal Canyon (Lucas 2009, unpublished data); this 
survey information indicates that these stands have survived after 
repeated fire events. Additionally, Thorne's hairstreak butterfly has 
been observed perching on H. forbesii and nectaring on other chaparral 
plants during multiple survey periods between and following the 2003 
and 2007 fires that occurred in the Otay Mountain area (Betzler et al. 
2003, pp. 13-14; Martin 2004, pers. comm.; Faulkner and Klein 2005, p. 
32; Lucas 2009, unpublished data).
    For additional species information on Thorne's hairstreak 
butterfly, please refer to our previous 90-day finding, which published 
in the Federal Register on August 8, 2006 (71 FR 44980).

[[Page 17065]]

Evaluation of Information for this Finding

    Section 4 of the Act (16 U.S.C. 1533), and its implementing 
regulations in the Code of Federal Regulations (CFR) at 50 CFR 424, set 
forth the procedures for adding species to the Federal Lists of 
Endangered and Threatened Wildlife and Plants. A species may be 
determined to be an endangered or threatened species due to one or more 
of the five factors described in section 4(a)(1) of the Act: (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.
    In making this 90-day finding, we evaluated whether information on 
threats to Thorne's hairstreak butterfly, as presented in the 2004 
petition and other information available in our files, is substantial, 
thereby indicating that the petitioned action may be warranted. In the 
sections that follow, we summarize information included in the 2004 
petition and evaluate any new information in our files, including 
information that has become available since the publication of the not-
substantial 90-day finding on August 8, 2006. For a detailed evaluation 
of threats listed in the petition, please refer to the previous 90-day 
finding that published in the Federal Register on August 8, 2006 (71 FR 
44980).

A. The Present or Threatened Destruction, Modification, or Curtailment 
of the Species' Habitat or Range

    The petition, its appendices, and referenced documents discuss the 
following threats that are grouped under Factor A: wildfire, prescribed 
burns, grazing, vehicle access and recreation, and habitat 
fragmentation.

Wildfire

Information Provided in the Petition
    The petitioners assert that Thorne's hairstreak butterfly is 
vulnerable to extinction from wildfire, which can cause direct 
mortality of individual butterflies (see discussion under Factor E) and 
indirect mortality resulting from a loss of the species' larval host 
plant, Hesperocyparis forbesii. The petition further asserts that a 
single fire may threaten a significant portion of Thorne's hairstreak 
butterfly's range (such as the 2003 fire, as cited in Betzler et al. 
2003, p. 13). Additionally, increased fire frequency throughout the 
species' range may result in an increase in the abundance or an 
expansion of highly flammable, invasive, nonnative plant species, or 
vegetation type conversion and the replacement of chaparral ecosystems 
with nonnative plant species, thereby impacting the habitat on which 
Thorne's hairstreak butterfly depends (Keeley and Fotheringham 2003, 
pp. 243-245; Brooks et al. 2004, pp. 677-688).
Evaluation of Information Provided in the Petition and Available in 
Service Files
    Distribution of Thorne's hairstreak butterfly is limited to the 
Otay Mountain area (part of the San Ysidro Mountain range in southern 
San Diego County, California) and is dependent on the presence of 
Hesperocyparis forebesii, which is the butterfly's larval host plant 
(Brown 1983, pp. 245-254). The current distribution of H. forbesii in 
the Otay Mountain area encompasses 454 ac (183 ha) (Lucas 2009, 
unpublished data); however, historical records indicate that H. 
forbesii in the Otay Mountain area once covered approximately 7,500 ac 
(3,035 ha) (CNDDB 2003). Of the current 454 ac (183 ha) of H. forbesii, 
approximately 34.7 ac (14 ha) are privately owned, 7.6 ac (3 ha) are 
owned by California Department of Fish and Game, and 5.5 ac (2.2 ha) 
are owned by the City of Chula Vista. The remaining approximately 406 
ac (164 ha) of H. forbesii habitat in the Otay Mountain area occurs 
within the Bureau of Land Management (BLM) Otay Mountain Wilderness 
(see Factor D for more information on the Otay Mountain Wilderness). 
Confirmed observations of Thorne's hairstreak butterfly have been 
reported throughout the Otay Mountain area, but primarily occur from 
two canyons: Little Cedar Canyon and Cedar Canyon both within the Otay 
Mountain Wilderness (Betzler et al. 2003, pp. 13-14). Thorne's 
hairstreak butterfly is a narrow endemic species with historically 
declining habitat throughout the Otay Mountain area (Brown 1983, pp. 
245-254; BLM 2009(b), p. 3-59); Congedo and Williams 2009, p. 1).
    Information in our files indicates that wildfires in 2003 and 2007 
burned throughout the Hesperocyparis forbesii stands in the Otay 
Mountain area, which are known to be occupied by Thorne's hairstreak 
butterfly. The rapid reburning of this area (fire intervals less than 
40 years) may have impacted mature H. forbesii by keeping them at a 
growth stage where reproductive output is not high enough to sustain 
the population of H. forbesii (de Gouvenain and Ansary 2006, pp. 447-
448; Markovchick-Nicholls 2007, p. 7); therefore, the availability of 
larval habitat for Thorne's hairstreak butterfly may be reduced by 
wildfires. It is also possible that replacement of other chaparral 
species (i.e., nectar sources) may have occurred under this fire 
regime, thereby removing nectar sources necessary to support Thorne's 
hairstreak butterfly; however, we have no information to support the 
petitioners' claim, and we will investigate this in our status review 
of the species. It is likely that wildfires will occur within the range 
of this species in the future. Therefore, we find the petition and 
information in our files presents substantial information indicating 
that listing Thorne's hairstreak butterfly may be warranted due to the 
threat of short-return-interval wildfire.

Prescribed Burns

Information Provided in the Petition
    The petitioners state that while prescribed burns do not appear to 
be planned by BLM for the San Ysidro Mountain range, any that do occur 
in the future could compound the threat of excessive fire to Thorne's 
hairstreak butterflies and Hesperocyparis forbesii.
Evaluation of Information Provided in the Petition and Available in 
Service Files
    We did not find substantial information in the petition or in our 
files to indicate prescribed burns by BLM in the San Ysidro Mountain 
range may threaten Thorne's hairstreak butterfly. The species and its 
larval plant host, Hesperocyparis forbesii, occur almost exclusively 
(approximately 90 percent) in the Otay Mountain Wilderness (see also 
Factor D). BLM's South Coast Resource Management Plan (South Coast RMP) 
(BLM 1994) generally allows prescribed burns; however, the Otay 
Mountain Wilderness has been managed under a policy of complete fire 
suppression (Woychok 2006, pers. comm.). In the Cedar Canyon area, the 
South Coast RMP states that BLM will not consider prescribed burns 
until 2020 to minimize the risk of jeopardizing H. forbesii 
regeneration after fires (BLM 1994, p. 21). Additionally, BLM is 
currently drafting a revised South Coast RMP that includes no 
prescribed burns and follows fire suppression practices until H. 
forbesii returns to its historical fire cycle of 50 years (BLM 2009(b), 
pp. 4-171-4-172). After 50 years without fire in a give H. forbesii 
stand, BLM would allow prescribed burns up to 500 ac per year. However, 
this new South Coast RMP is

[[Page 17066]]

in an early draft stage and is not currently being implemented by BLM. 
The other locations in the Otay Mountain area that contain H. forbesii 
stands (approximately 10 percent) receive protection under the City of 
Chula Vista Subarea Plan or the County of San Diego Subarea Plan under 
the Multiple Species Conservation Program (MSCP). These subarea plans 
require the conservation of natural vegetation communities (including 
H. forbesii stands), and states that ``a fire management program would 
be needed for prevention of catastrophic fires and long-term 
viability'' of both Thorne's hairstreak butterfly and its larval host 
plant. Therefore, we find the petition and information in our files do 
not present substantial information indicating that listing Thorne's 
hairstreak butterfly may be warranted due to the threat of prescribed 
burns. However, we will further investigate the potential threat of 
prescribed burns in our status review for this species.

Grazing

Information Provided in the Petition
    The petition states that grazing may harm Thorne's hairstreak 
butterfly and its larval host plant, Hesperocyparis forbesii, if 
grazing within the currently vacant Otay Grazing Allotment 
(approximately 5,522 ac (2,235 ha) (BLM 2009(b), p. 3-116) located on 
BLM lands on Otay Mountain) occurs in the future. The threat of grazing 
as it relates to direct mortality of individual butterflies is 
discussed under Factor E. The petitioners assert that the allotment is 
being considered for renewed grazing in the future and that cattle 
grazing will cause harm to the habitat (by trampling the larval host 
and through soil modification) and increase the occurrence of nonnative 
plants, thus leading to an increase in fire frequency, and resulting in 
loss of Thorne's hairstreak butterfly habitat.
Evaluation of Information Provided in the Petition and Available in 
Service Files
    The petitioners state that the Otay Grazing Allotment is vacant. 
Information in our files indicates the allotment is leased but has been 
in a state of non-use since 2000 (BLM 2009(b), p. 3-120). The Otay 
Grazing Allotment is completely contained within the Otay Mountain 
Wilderness and encompasses suitable adult Thorne's hairstreak butterfly 
habitat (i.e., the host plant and other chaparral plants, which 
includes nectar sources for adults) (Lucas 2009, pers. comm.), 
including approximately 16 percent (75.2 ac (30.4 ha)) of the 
Hesperocyparis forbesii in the Otay Mountain area. The available adult 
and larval habitat for Thorne's hairstreak butterfly is currently not 
impacted by grazing and a large majority of the adult and larval 
habitat would remain unaffected if grazing resumed in the Otay Grazing 
Allotment in the future. Neither the petition nor other information in 
our files presents substantial information indicating that listing 
Thorne's hairstreak butterfly may be warranted due to the threat of 
grazing. However, we will further investigate the potential threat of 
grazing in our status review for this species.

Vehicle Access and Recreation

Information Provided in the Petition
    The petitioners assert that vehicle access and recreation in the 
San Ysidro Mountain range will likely lead to increased fire frequency. 
Additionally, they state that certain roads were grandfathered into the 
Otay Mountain Wilderness designation and generally allow unrestricted 
public access to Thorne's hairstreak butterfly habitat.
Evaluation of Information Provided in the Petition and Available in 
Service Files
    The Otay Mountain Wilderness Area allows public access; however, 
recreational use is considered light with no more than 1,000 visitor 
use days per year (BLM 2009(b), p. 3-103). Visitors are encouraged to 
be responsible and follow the BLM program called ``Leave No Trace,'' 
which minimizes impacts from human uses. Motorized vehicle use is not 
permitted in the designated Wilderness Area with the exception of two 
pre-existing roads, and off-highway vehicles are completely excluded 
(BLM 2009(b), pp. 2-124-2-125). The majority of traffic through the 
area is concentrated on a few small roads used by border patrol agents. 
Border patrol vehicles may increase the risk of fire in this area, 
although fires are expected to be immediately reported (BLM 2009(b), p. 
2-151).
    Although light recreational use and minimal traffic associated with 
border patrol agents occurs in the Otay Mountain Wilderness, the 
information available to us does not indicate that recreation and 
vehicle use is a threat to Thorne's hairstreak butterfly. These two 
pre-existing roads within the Otay Mountain Wilderness extend outside 
of BLM property onto private lands; however, they are small, one-lane, 
remote, dirt roads that only pass near stands of Hesperocyparis 
forbesii and do not appear to be heavily used. We do not have 
information to support the claim that vehicle access would increase the 
fire frequency in the area. Additionally, we do not have information in 
our files and the petitioners did not present information to indicate 
that vehicle access and recreation are a threat to the species in the 
Otay Mountain Wilderness or in privately-owned areas. Therefore, we 
find the petition and information in our files do not present 
substantial information indicating that listing Thorne's hairstreak 
butterfly may be warranted due to the threat of vehicle access and 
recreation. However, we will further investigate the potential threat 
of recreation and vehicle access in our status review for this species.

Habitat Fragmentation

Information Provided in the Petition
    The petitioners claim that both habitat fragmentation and habitat 
degradation pose a substantial threat to Thorne's hairstreak butterfly 
and its habitat through both habitat modification and fragmentation of 
butterfly populations. The petitioners assert that the habitat has been 
degraded and modified such that Thorne's hairstreak butterfly is unable 
to locate suitable habitat, which will likely impact the species 
throughout its geographical range. The impacts associated with Thorne's 
hairstreak butterfly population fragmentation are assessed under Factor 
E (see below).
Evaluation of Information Provided in the Petition and Available in 
Service Files
    We agree that habitat for Thorne's hairstreak butterfly appears to 
have been fragmented or degraded by wildfire. The current distribution 
of Hesperocyparis forbesii in the Otay Mountain area encompasses 454 ac 
(183 ha) (Lucas 2009, unpublished data) and is distributed in patches 
across the landscape; however, historical records indicate that H. 
forbesii in the Otay Mountain area once covered approximately 7,500 ac 
(3,035 ha). Information in our files indicates that H. forbesii and 
other chaparral species are currently recovering after recent fires 
(Congedo and Williams 2009, p. 1; Lucas 2009, pers. comm.); however, we 
do not have information in our files that indicates whether the habitat 
has been impacted in a manner that would inhibit recovery to historical 
levels. We note that the amount of larval habitat has increased from 
2004 to 2009 (Lucas 2009, unpublished data).
    Zedler et al. (1983, pp. 809-818) describes vegetation type 
conversion

[[Page 17067]]

(also considered a type of habitat fragmentation) within the Otay 
Mountain area; however, information in our files describes recovering 
H. forbesii habitat and availability of various suitable nectar sources 
after the fires in 2003 and 2007, including one source that was 
previously unknown (Lucas 2009, pers. comm.).
    Additionally, the petition cites roads as a mechanism of habitat 
fragmentation; however, roads are unlikely to cause habitat 
fragmentation to an extent that would impact Thorne's hairstreak 
butterfly population because the roads are small, one-lane, remote, 
dirt roads with little traffic. The Otay Mountain Wilderness, managed 
by the BLM, has only two main roads and a few other small roads that 
allow motorized vehicles (off-highway vehicle use is excluded 
throughout the Otay Mountain Wilderness); therefore, habitat 
fragmentation resulting from roads would be very minimal.
    In summary, we evaluated the petition and information in our files 
and find that substantial information exists to indicate that listing 
Thorne's hairstreak butterfly may be warranted due to the present or 
threatened destruction, modification, or curtailment of the habitat or 
range of the species due to the threat of wildfires and the possibility 
that habitat fragmentation may be occurring as a result of wildfires. 
We will further investigate the potential threat of habitat 
fragmentation in our status review for this species.

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

Information Provided in the Petition
    The petition does not present any information with respect to 
Factor B.
Evaluation of Information Provided in the Petition and Available in 
Service Files
    The information in our files does not indicate any threat to 
Thorne's hairstreak butterfly due to overutilization for commercial, 
recreational, scientific, or education purposes. Therefore, we find 
that the petition and information in our files do not provide 
substantial information indicating listing Thorne's hairstreak 
butterfly may be warranted due to the overutilization for commercial, 
recreational, scientific, or education purposes. However, we will 
further investigate the potential threat of overutilization for 
commercial, recreational, scientific, or education purposes in our 
status review for this species.

C. Disease or Predation

Disease

Information Provided in the Petition
    The petition does not present any information concerning threats 
from disease to Thorne's hairstreak butterfly.
Evaluation of Information Provided in the Petition and Available in 
Service Files
    We have no information in our files to indicate any threat from 
disease to Thorne's hairstreak butterfly.

Predation

Information Provided in the Petition
    The petitioners state that species experts (Klein (date not 
provided), pers. comm.) suspect that birds, predatory insects, 
parasitic insects, and spiders prey upon Thorne's hairstreak butterfly. 
Additionally, the petitioners assert that the harmful effects of 
otherwise normal predation or parasitism might be exacerbated by 
population reduction from excessive fires.
Evaluation of Information Provided in the Petition and Available in 
Service Files
    Faulkner and Klein (2005, p. 34) state that birds may consume 
Thorne's hairstreak larvae; however, we are not aware of any data to 
support a theory of bird predation as a significant threat to Thorne's 
hairstreak butterflies. Brachonid wasps, which are parasitic insects, 
have been observed near the host plant, but there has been no 
documentation of parasitism to Thorne's hairstreak butterflies 
(Faulkner and Klein 2005, p. 34). The petitioners do not provide 
information to support their claim that predation or parasitism may 
exacerbate population reduction resulting from fires, nor do we have 
any information in our files to support this claim.
    Neither the petition nor our files present substantial information 
that disease or predation pose significant threats to Thorne's 
hairstreak butterfly. Therefore, we find that the petition and 
information in our files do not provide substantial information 
indicating that listing Thorne's hairstreak butterfly may be warranted 
due to disease or predation. However, we will further investigate the 
potential threat of disease and predation in our status review for this 
species.

D. The Inadequacy of Existing Regulatory Mechanisms

    The petition cites three regulatory mechanisms that may provide 
some, but not adequate, Thorne's hairstreak butterfly conservation, 
including:
    (1) The Wilderness Act,
    (2) BLM management activities, and
     (3) The County of San Diego Subarea Plan under the Multiple 
Species Conservation Program (MSCP).
Information Provided in the Petition
    The petitioners make the following statements concerning Thorne's 
hairstreak butterflies and the Wilderness Act, BLM management 
activities, and the County of San Diego Subarea Plan:
    (1) The Wilderness Act does not provide significant protection for 
the species;
    (2) BLM does not consider the species as ``sensitive'', so the 
species is not afforded sensitive species' protections within the 
agency's management plan (i.e., the South Coast RMP));
    (3) BLM is not actively implementing conservation measures for the 
species;
    (4) BLM is not pro-actively managing the private lands they have 
acquired; and
     (5) Despite Thorne's hairstreak butterfly being recognized as a 
``covered species'' under the County of San Diego Subarea Plan, that 
Plan does not provide sufficient protection for the species.
Evaluation of Information Provided in the Petition and Available in 
Service Files
    Thorne's hairstreak butterfly larval habitat on Otay Mountain 
occurs almost entirely (92 percent) on publicly owned property (BLM, 
City of Chula Vista or California Department of Fish and Game). The 
following regulatory mechanisms and management actions apply to these 
public lands and protect Thorne's hairstreak butterfly and its habitat:
     (1) The Otay Mountain Wilderness Act (1999) (Pub. L. 106-145) and 
BLM management policies provide protection for the vast majority of 
Thorne's hairstreak butterfly habitat. The Otay Mountain Wilderness Act 
provides that the Otay Mountain designated wilderness area (i.e., Otay 
Mountain Wilderness; 18,500 ac (7,486 ha)) will be managed in 
accordance with the provisions of the Wilderness Act of 1964 (16 U.S.C. 
1131 et seq.). The Wilderness Act of 1964, in turn, strictly limits use 
of wilderness areas, imposing restrictions on vehicle use, new 
developments, chainsaws, mountain bikes, leasing, and mining in order 
to protect the natural habitats of the areas,

[[Page 17068]]

maintain species diversity, and enhance biological values. Finally, any 
lands acquired within the Otay Mountain Wilderness boundaries become 
part of the designated wilderness area and they are managed in 
accordance with all provisions of the Wilderness Act and applicable 
laws.
     (2) Sensitive species, as defined by BLM, are those species that 
are not already designated as Federal- or State-listed species and 
occur on Bureau-administered lands for which BLM has the capability to 
significantly affect their conservation status through management. This 
BLM policy is intended to ensure that actions authorized, funded, or 
carried out by the BLM do not contribute to the need for these species 
to become listed as endangered or threatened under the Act (BLM 
2009(b), p. 3-58). Currently, Thorne's hairstreak butterfly is not 
considered a sensitive species by BLM; however, BLM is currently 
collaborating with the Service to revise the South Coast RMP. In this 
draft revised plan, Thorne's hairstreak butterfly and Hesperocyparis 
forbesii are identified as sensitive species (BLM 2009(b), p. 3-59), 
and the draft revised plan specifically states the management of these 
species and their habitats are important because of their close 
association and the importance of fire cycles to their continued 
existence. Moreover, one of BLM's primary objectives in the draft 
revised plan is improved fire management and collaboration with local 
communities and agencies to prevent wildfires. Additionally, BLM 
intends to write a more specific plan for the Otay Mountain Wilderness 
that identifies management measures and actions that would benefit H. 
forbesii (Schlachter 2006, pers. comm.; BLM 2009(a), p. 1). BLM's 
future management plans appear to provide a significant amount of 
conservation and management measures, but they are currently not being 
implemented throughout the Otay Mountain Wilderness Area. As a result 
of wildfires on Otay Mountain there have likely been increases in 
nonnative species which increase fuels available for future fires. 
Furthermore, although the current fire suppression policy dictates all 
fires should be suppressed once ignited, this has not prevented recent 
wildlfires from burning through large areas of Thorne's hairstreak 
butterfly habitat. Therefore, it appears current regulations for 
Thorne's hairstreak butterfly and its habitat are not adequate to 
control the threat of increased wildfire frequency.
     (3) The Memorandum of Understanding (MOU) on cooperation in 
habitat conservation planning and management issued by BLM in 1994 in 
conjunction with the development of the County of San Diego Subarea 
Plan (BLM 1994, pp. 1-8) applies to the Otay Mountain Wilderness 
because it falls entirely within the boundary of this subarea plan. The 
MOU details BLM's commitment to manage its lands in a manner that 
compliments the County of San Diego MSCP Subarea Plan, which in turn, 
requires protection of Thorne's hairstreak butterfly's larval host 
plant and local chaparral species used as nectar sources. Additionally, 
the MOU states that private lands acquired by BLM will be evaluated for 
inclusion within the designated wilderness area and if the lands do not 
meet wilderness qualifications they would be included in the region's 
habitat conservation system (BLM 1994, p. 3). Any existing conservation 
plans will be considered when managing these newly acquired lands (BLM 
1994, p. 3; BLM 2009(b), pp. 2-74, N-1-2).
    The draft revised South Coast RMP (see discussion in (2) above) , 
which covers the Otay Mountain Wilderness, does provide conservation 
measures for both Thorne's hairstreak butterfly and Hesperocyparis 
forbesii. The plan specifically includes a goal of restoring fire 
frequency to 50 years through fire prevention or suppression and 
prescribed burns; once an area has not burned for 50 years the plan 
allows for annual prescribed burning of up to 500 acres (202.3 ha) in 
the Otay Mountain Wilderness (BLM 2009(b), pp. 4-171-4-172). BLM's 
future management plans appear to provide conservation and management 
measures to assist with various threats to Thorne's hairstreak 
butterfly and its habitat, but they are currently not being implemented 
throughout the Otay Mountain Wilderness Area; therefore, it appears 
that current regulations for Thorne's hairstreak butterfly and its 
habitat are not adequate to control potential threats to this species, 
including the threat of increased wildfire frequency.
     (4) Approximately 48 ac (19 ha) of Hesperocyparis forbesii habitat 
fall under the MSCP, which strives for fire management and prevention 
to restore the previous 25-year fire cycle and states that ``a fire 
management program would be needed for prevention of catastrophic fires 
and long-term viability of its host plant.'' This shorter frequency of 
fire may have an impact on adult H. forbesii because they will not have 
the opportunity to reach an age (40 or more years) where reproductive 
output is high enough to sustain the population (de Gouvenain and 
Ansary 2006, pp. 447-448; Markovchick-Nicholls 2007, p. 7). Therefore, 
the fire management and prevention policies of the MSCP which strive to 
restore a 25 year fire cycle, may be inadequate to control the threat 
of wildfire to this species.
    There appear to be a variety of future management actions that BLM 
couldimplement which may provide protection to Thorne's hairstreak 
butterfly and its habitat; however, current existing regulatory 
mechanisms by BLM and MSCP do not appear to be adequate to provide 
protection for Thorne's hairstreak butterfly or its habitat from the 
threat of increased wildfire frequency. Therefore, after our evaluation 
of the petition and information in our files, we find that substantial 
information exists to indicate that listing Thorne's hairstreak 
butterfly may be warranted due to the inadequacy of existing regulatory 
mechanisms.

E. Other Natural or Manmade Factors Affecting the Species' Continued 
Existence

    The petition, its appendices, and referenced documents discuss the 
following threats that are grouped under Factor E: wildfire, grazing, 
population fragmentation, vulnerability of small and isolated 
populations, and global climate change.

Wildfire

Information Provided in the Petition
    The petitioners state that Thorne's hairstreak butterfly cannot 
escape fire. They stated that: (1) Pupae and larvae are likely killed 
when fire burns Hesperocyparis forbesii stands and nearby chaparral; 
(2) adults are likely killed by fire due to their habit of remaining 
close to their host plant; and (3) adults are likely outpaced by an 
approaching fire. The petition claims excessive fires over the last 
several decades have reduced Thorne's hairstreak butterfly population 
numbers and disrupted metapopulation dynamics and stability.
Evaluation of Information Provided in the Petition and Available in 
Service Files
    We agree that the majority of Thorne's hairstreak butterfly 
individuals are likely killed when a fire passes through an occupied 
area. Moreover, researchers questioned the persistence of Thorne's 
hairstreak butterfly after the 2003 Otay/Mine fire because the fire 
footprint appeared to cover all areas known to be occupied by the 
species (IBAERT 2003, pp. 219-220; Betzler et al. 2003, p. 13). 
Although, adult Thorne's hairstreak butterflies were documented from 
four

[[Page 17069]]

unburned Hesperocyparis forbesii stands after the 2003 fire on the 
southwest slope of the Otay Mountain (Martin 2004, pers. comm.), 
surveyors in 2004 visiting the burned areas occupied prior to the 2003 
fire, found evidence of new host plant growth but no adult Thorne's 
hairstreak butterflies (Faulkner and Klein 2005, pp. 32). This is 
likely due to the lack of available larval host plants and nectar 
sources on which Thorne's hairstreak butterfly relies one year after 
the fire.
     Researchers have postulated that Thorne's hairstreak butterflies 
require mature host plants for reproduction (Faulkner and Klein 2005, 
p. 32); however, Thorne's hairstreak butterflies were observed in 2009 
perching and feeding within re-growth areas burned in the 2003 and 2007 
fires (Lucas 2009, pers. comm.). These observations in recently burned 
(younger) stands of H. forbesii support the theory that Thorne's 
hairstreak butterflies do not strictly require mature or adult trees as 
host plants.
    Even with some post-fire adult observations, it is likely the 
majority of Thorne's hairstreak butterflies killed when habitat burns 
and populations are further adversely impacted by frequently recurring 
fires. Therefore, we find that the petition and information in our 
files do provide substantial information to indicate that listing 
Thorne's hairstreak butterfly may be warranted due to direct mortality 
from wildfire.

Grazing

Information Provided in the Petition
    The petitioners assert that grazing practices may lead to trampling 
of eggs and larvae of Thorne's hairstreak butterfly.
Evaluation of Information Provided in the Petition and Available in 
Service Files
    The Otay Grazing Allotment, which is the only place in the current 
range of the species that is grazed, is completely contained within the 
Otay Mountain Wilderness and has not been grazed since 2000 (Doran 
2006, pers. comm.; BLM 2009(b), p. 3-120). Information in our files 
indicate that approximately 84 percent (378 ac (153 ha)) of the 
Hesperocyparis forbesii within the Otay Mountain area are outside of 
the Otay Grazing Allotment. The majority of the available habitat for 
Thorne's hairstreak butterfly is currently not affected by grazing 
(i.e., vegetation conditions are not favorable for grazing), and would 
not be affected by grazing within the Otay Grazing Allotment should 
grazing in the allotment resume in the future. Therefore, we find that 
the petition and information in our files do not provide substantial 
information to indicate that listing Thorne's hairstreak butterfly may 
be warranted due to mortality from grazing. However, we will further 
investigate in our status review for this species the potential threat 
of trampling mortality from grazing and the potential impact that 
grazing could have if it occurs in the future.

Population Fragmentation

Information Provided in the Petition
    The petitioners state that fragmentation of Thorne's hairstreak 
butterfly populations through fire, habitat type conversion, and roads 
poses a significant threat to the species. The petitioners claim 
habitat fragmentation reduces the area of Thorne's hairstreak butterfly 
habitat and thereby threatens the species by isolating populations from 
one another. The petitioners also claim that because Thorne's 
hairstreak butterflies are habitat specialists, they have a higher risk 
of extinction due to population fragmentation than a habitat 
generalist. Additionally, the petitioners claim that habitat 
fragmentation expands edge habitat, resulting in further stress on 
fragmented or small populations, leading to isolation effects on the 
population.
Evaluation of Information Provided in the Petition and Available in 
Service Files
    The petition describes the Thorne's hairstreak butterfly population 
as fragmented as a result of habitat fragmentation. Hesperocyparis 
forbesii and associated chaparral habitat has been disturbed by 
wildfire; however, this habitat is recovering and Thorne's hairstreak 
butterflies continue to occur throughout the burned area (Martin 2004, 
pers. comm.; Faulkner and Klein 2005, pp. 32-33; Congedo and Williams 
2009, p. 1; Lucas 2009, pers. comm.). Even though movement dynamics 
have not been completely determined, information in our files indicates 
Thorne's hairstreak butterfly is capable of re-colonizing and utilizing 
immature H. forbesii stands in recently burned areas (Martin 2004, 
pers. comm.; Faulkner and Klein 2005, p. 32; Lucas 2009, pers. comm.). 
New information indicating that Asclepias fascicularis, a previously 
unknown nectar source (Lucas 2009, pers. comm.), is used by Thorne's 
hairstreak butterfly indicate that the butterfly's habitat requirements 
may not be as specialized as previously thought.
    The petition states that individuals have been observed nectaring 
0.25 mile (0.40 kilometer) away from their host plant, which suggests 
that individual butterflies are capable of moving at least this far to 
find suitable habitats or mates. However, information in our files 
indicates that the H. forbesii stands are patchily distributed and 
separated by distances greater than 0.25 mile (0.40 kilometer), which 
may contribute to population fragmentation. As a result of this 
information, we find that the petition and information in our files 
provides substantial information indicating listing Thorne's hairstreak 
butterfly may be warranted due to population fragmentation. We intend 
to further investigate and attempt to distinguish between habitat 
fragmentation and population fragmentation in our status review of the 
species.

Vulnerability of Small and Isolated Populations

Information Provided in the Petition
    The petitioners assert that endemic taxa such as Thorne's 
hairstreak butterfly are considered more prone to extinction than 
widespread species due to their restricted geographical range. 
According to the petition, the common factors that increase the 
vulnerability of small and isolated populations to extinction are 
demographic fluctuations, environmental stochasticity (random events), 
and reduced genetic diversity.
Evaluation of Information Provided in the Petition and Available in 
Service Files
    The fact that a species is characterized by populations that are 
few in number, small in size, or isolated does not necessarily mean the 
species is threatened. Typically, it is the combination of small size 
and number of populations and isolation of small populations in 
conjunction with other threats (such as the present or threatened 
destruction, modification, or curtailment of the species' habitat or 
range) that may pose a threat to a species. Thorne's hairstreak 
butterfly has always been endemic the Otay Mountains (Brown 1983; 
Beztler et al. 2003; Faulkner and Klein 2005). If occupied habitat is 
temporarily fragmented by fire, a fluctuation in Thorne's hairstreak 
butterfly numbers could make small populations more vulnerable to 
stochastic events. Small populations and the isolation of populations 
from one another could also subject Thorne's hairstreak butterfly to 
genetic drift and restrict gene flow that may decrease genetic 
variability over

[[Page 17070]]

time and could adversely affect the species' viability (Allee 1931, pp. 
12-37; Stephens et al. 1999, pp. 185-190; Dennis 2002, pp. 389-401). 
Surveys conducted in 2009 (Lucas 2009, unpublished data) conclude that 
Thorne's hairstreak butterflies are still present in the H. forbesii 
stands on Otay Mountain. We have no quantitative survey information on 
population numbers, but historical larval habitat has been reduced from 
7,500 ac (3,035 ha) to approximately 454 ac (see ``Habitat'' section 
above for more information). Since Thorne's hairstreak butterfly is 
dependent on H. forbssi to complete its lifecycle, available larval 
habitat is a proxy for population size. With this large reduction in 
available larval habitat we believe that the species' population 
distribution have been significantly reduced relative to historical 
levels resulting in an increased risk of extinction due to stochastic 
events such as wildfire. Therefore, we find that the petition and 
information in our files do provide substantial information indicating 
that listing Thorne's hairstreak butterfly may be warranted due to 
restricted geographic range.

Global Climate Change

Information Provided in the Petition
    The petitioners assert that butterflies (in general) are threatened 
by global climate change and are sensitive to small changes in 
microclimates, such as fluctuations in moisture, temperature, or 
sunlight. According to the petition, studies of Edith's checkerspot 
butterfly (Euphydryas editha) have verified speculation that whole 
ecosystems may move northward or shift in elevation as the Earth's 
climate warms (Parmesan and Galbraith 2004, p. 9).
Evaluation of Information Provided in the Petition and Available in 
Service Files
    We recognize recent evaluations by Parmesan and Galbraith (2004, 
pp. 1-2, 29-33) that indicate whole ecosystems may be shifting 
northward and upward in elevation, or are otherwise being altered by 
differing climate tolerance among species within a community. 
Parmesan's review (2006, pp. 637, 648-649, 653) indicates range-
restricted mountaintop species (such as Thorne's hairstreak butterfly) 
typically experience range retractions. Additionally, we recognize that 
climate change is likely to cause changes in the arrangement of 
occupied habitat patches. Current climate change predictions for 
terrestrial areas in the Northern Hemisphere indicate warmer air 
temperatures, more intense precipitation events, and increased summer 
continental drying (Field et al. 1999, pp. 1-3; Hayhoe et al. 2004, p. 
12422; Cayan et al. 2005, p. 6; Intergovernmental Panel on Climate 
Change 2007, p. 11). However, predictions of climatic conditions for 
smaller subregions such as California remain uncertain. It is unknown 
at this time if climate change in California will result in a warmer 
trend with localized drying, higher precipitation events, or other 
effects. Because, the information currently available on the effects of 
global climate change and microhabitat changes, such as increasing 
temperatures or moisture, does not make sufficiently precise estimates 
of the magnitude of the effects, we are unable to determine what 
impacts to Thorne's hairstreak butterfly may occur. Given this 
uncertainty, we find that the petition and information in our files do 
not provide substantial information to indicate that listing Thorne's 
hairstreak butterfly may be warranted do to global climate change. We 
will further investigate this potential threat to Thorne's hairstreak 
butterfly in our status review of the species.
    In summary, we find that the petition and information in our files 
do provide substantial information indicating that listing Thorne's 
hairstreak butterfly may be warranted due to other natural or manmade 
factors affecting the species' continued existence. Specifically, we 
find that the effects of wildfire on individuals, population 
fragmentation, and restricted geographic range+may pose significant 
threats to the species.

Finding

    On the basis of our determination under section 4(b)(3)(A) of the 
Act, we have determined that the petition presents substantial 
scientific or commercial information indicating that listing Thorne's 
hairstreak butterfly may be warranted. This finding is based on 
information provided under Factor A (present or threatened destruction, 
modification, or curtailment of the species' habitat or range), Factor 
D (the inadequacy of existing regulatory mechanisms) and Factor E 
(other natural or manmade factors affecting the species' continued 
existence). Because we have found that the petition presents 
substantial information indicating that listing Thorne's hairstreak 
butterfly may be warranted, we are initiating a status review to 
determine whether listing Thorne's hairstreak butterfly under the Act 
is warranted.
    The ``substantial information'' standard for a 90-day finding 
differs from the Act's ``best scientific and commercial data'' standard 
that applies to a status review to determine whether a petitioned 
action is warranted. A 90-day finding does not constitute a status 
review under the Act. In a 12-month finding, we will determine whether 
a petitioned action is warranted after we have completed a thorough 
status review of the species, which is conducted following a 
substantial 90-day finding. Because the Act's standards for 90-day and 
12-month findings are different, as described above, a substantial 90-
day finding does not mean that the 12-month finding will result in a 
warranted finding.
    The petitioners request that we designate critical habitat for this 
species. If we determine in our 12-month finding that listing Thorne's 
hairstreak butterfly is warranted, we will address the designation of 
critical habitat at the time of the proposed rulemaking. The proposed 
rulemaking may be published concurrently with the 12-month finding or 
at a later date.

References Cited

    A complete list of references cited is available on the Internet at 
http://www.regulations.gov and upon request from the Carlsbad Fish and 
Wildlife Office (see FOR FURTHER INFORMATION CONTACT).

Author

    The primary authors of this notice are staff members of the 
Carlsbad Fish and Wildlife Office (see FOR FURTHER INFORMATION 
CONTACT).

Authority

    The authority for this action is the Endangered Species Act of 
1973, as amended (16 U.S.C. 1531 et seq.).

    Dated: March 26, 2010.
Jeffrey L. Underwood,
Acting Director, Fish and Wildlife Service.
[FR Doc. 2010-7547 Filed 4-2-10; 8:45 am]
BILLING CODE 4310-55-S