[Federal Register Volume 75, Number 80 (Tuesday, April 27, 2010)]
[Proposed Rules]
[Pages 22063-22070]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-9377]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[FWS-R8-ES-2010-0006]
[MO 92210-0-0008 B2]


Endangered and Threatened Wildlife and Plants; 90-day Finding on 
a Petition to List the Mohave Ground Squirrel as Endangered with 
Critical Habitat

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 90-day 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 the Mohave ground squirrel 
(Xerospermophilus mohavensis) as an endangered species under the 
Endangered Species Act of 1973, as amended (Act). Based on our review, 
we find that the petition presents substantial scientific or commercial 
information indicating that listing the Mohave ground squirrel may be 
warranted. Therefore, with the publication of this notice, we are 
initiating a status review of the species to determine if listing the 
species is warranted. To ensure that this 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. We will make a determination on critical habitat 
for this species, which was also requested in the petition, if and when 
we initiate a listing action.

DATES: To allow us adequate time to conduct this review, we request 
that we receive information on or before June 28, 2010. After this 
date, you must submit information directly to the Ventura 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 date noted above.

ADDRESSES: You may submit information by one of the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov. 
Search for docket FWS-R8-ES-2010-0006 and then follow the instructions 
for submitting comments.
     U.S. mail or hand-delivery: Public Comments Processing, 
Attn: FWS-R8-ES-2010-0006; 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 Solicited 
section below for more information).

FOR FURTHER INFORMATION CONTACT: Michael McCrary, Listing and Recovery 
Coordinator, Ventura Fish and Wildlife Office, 2593 Portola Road, Suite 
B, Ventura, CA 93003; telephone (805) 644-1766; facsimile (805) 644-
3958. If you use a telecommunications device for the deaf (TDD), call 
the Federal Information Relay Service (FIRS) at (800) 877-8339.

SUPPLEMENTARY INFORMATION:

Information Solicited

    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 
Mohave ground squirrel from government 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;
    (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.

[[Page 22064]]

    (2) Historical and current survey information on the Mohave ground 
squirrel, including survey methods and design, time of year, weather 
information, time of day, site selection method, and descriptions of 
physical characteristics of landscapes, soil, and vegetation.
    (3) 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 the species' 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.
    (4) Information on management programs for the conservation of the 
Mohave ground squirrel.
    (5) Information on current or expected future development within 
the range of the Mohave ground squirrel, including but not limited to: 
the extent or magnitude of habitat loss, degradation, or fragmentation 
from development for energy, transportation, agriculture, military 
training; land management prescriptions; or recreation, and how they 
may affect the conservation of the Mohave ground squirrel.
    (6) Information on the population status of predators of the Mohave 
ground squirrel, including information on the occurrence and extent/
severity of predation by coyotes, house cats, common ravens, domestic 
dogs, and feral dogs on the Mohave ground squirrel, and the effect of 
this predation on the Mohave ground squirrel's long-term survival.
    (7) Information on morphological, behavioral, genetic, or 
ecological variability in the Mohave ground squirrel, and any change in 
that variability.
    (8) Information on environmental change within the range of the 
Mohave ground squirrel.
    (9) Information on the importance of certain areas or populations 
to the long-term conservation of the Mohave ground squirrel that may 
help us identify potentially significant portions of the species' 
range. This may include information that demonstrates the following 
factors are important to a portion of the Mohave ground squirrel's 
range:
    (a) The quality, quantity, and distribution of habitat relative to 
the biological requirements of the species;
    (b) The historical values of the habitat to the species;
    (c) The frequency of use of the habitat; and
    (d) The uniqueness or importance of the habitat for other reasons, 
such as breeding, feeding, seasonal movements, wintering, or 
suitability for population expansion, or for genetic diversity.
    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 Mohave 
ground squirrel is warranted, we will 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 Mohave ground squirrel, 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, including managing for the potential 
effects of climate change.
    In addition, we request data and information on ``specific areas 
outside the geographical area occupied by the species'' that are 
``essential for 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 definition of critical 
habitat in section 3 of the Act and 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 finding 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 view. 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 public inspection at 
http://www.regulations.gov, or by appointment, during normal business 
hours, at the U.S. Fish and Wildlife Service, Ventura 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 this 
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 commence a review of the status of the species, which is 
subsequently summarized in our 12-month finding.

Petition History

    On September 5, 2005, we received a petition, dated August 30, 
2005, from Defenders of Wildlife and Dr. Glenn R. Stewart to list the 
Mohave ground squirrel as endangered, and to designate critical habitat 
concurrently with the listing. The petition identified the scientific 
name for Mohave ground squirrel as Spermophilus mohavensis; however, 
the name was changed in 2009 to Xerospermophilus mohavensis (Helgen et 
al. 2009, p. 273), and we refer to it in this petition finding by its 
current name. The petition clearly identified itself as such and 
included the requisite identification information for the petitioners, 
as required in 50

[[Page 22065]]

CFR 424.14(a). The petition contained detailed information on the 
natural history and biology of the Mohave ground squirrel, and the 
current status and distribution of the species. It also contained 
information on what the petitioners reported as potential threats to 
the species. In a March 28, 2006, letter to the petitioners, we 
informed them that we would not be able to address their petition at 
that time because further action on the petition was precluded by court 
orders and settlement agreements for other listing actions that 
required us to use nearly all of our listing funds for fiscal year 
2006. We also stated our initial review of the petition did not 
indicate that an emergency situation existed and that emergency listing 
was not necessary.

Previous Federal Actions

    On December 13, 1993, the Service received a petition dated 
December 6, 1993, from Dr. Glenn R. Stewart of California Polytechnic 
State University, Pomona, California, requesting the Service to list 
the Mohave ground squirrel as a threatened species. At that time, the 
species was a category 2 candidate (November 15, 1994; 59 FR 58988), 
and was first included in this category on September 18, 1985. Category 
2 included taxa for which information in the Service's possession 
indicated that listing the species as endangered or threatened was 
possibly appropriate, but for which sufficient data on biological 
vulnerability and threats were not available to support a proposed 
listing rule. On September 7, 1995, we published our 90-day petition 
finding, which determined that the 1993 petition did not present 
substantial information indicating that the petitioned action may be 
warranted (60 FR 46569).

Species Information

    The Mohave ground squirrel (Xerospermophilus mohavensis) is a 
distinct, full species with no recognized subspecies. The petitioners 
presented sufficient, reliable information related to the taxonomic 
status of the Mohave ground squirrel. It was discovered in 1886 by F. 
Stephens and described as a distinct monotypic species by Merriam 
(1889, p. 15). The type locality is near Rabbit Springs in the Lucerne 
Valley, San Bernardino County, California.
    The Mohave ground squirrel is a medium-sized squirrel. Total length 
is approximately 23 centimeters (cm) (9 inches (in)) with a tail length 
of 6.4 cm (2.5 in). The upper body is grayish brown, pinkish gray, 
cinnamon gray, and pinkish cinnamon without stripes or flecking. The 
underparts of the body and the tail are white (Ingles 1965, p. 171). 
The skin is darkly pigmented and dorsal hair tips are multi-banded.
    The closest relative of the Mohave ground squirrel is the round-
tailed ground squirrel (Xerospermophilus tereticaudus). It has a 
contiguous, but not overlapping, geographic range with the Mohave 
ground squirrel.
Mating and Reproduction
    The Mohave ground squirrel mating season occurs from mid-February 
to mid-March (Harris and Leitner 2004, p. 1). Recht (c.f. Gustafson 
1993, p. 83) reported that male Mohave ground squirrels are territorial 
during the mating season. Females may enter male Mohave ground squirrel 
territory and remain for 1 or 2 days. After copulation, the females 
establish their own home ranges. John Harris (personal communication, 
Mills College, Oakland, CA, as cited in the petition, p. 14) observed 
male Mohave ground squirrels staking out the overwintering sites of 
females to mate with them when they emerged.
    Gestation is about 30 days with litter size ranging from four to 
nine (Best 1995, p. 3). Parental care continues through mid-May, with 
juvenile Mohave ground squirrels emerging above ground between 10 days 
to 2 weeks later (Gustafson 1993, p. 84). Mortality for juveniles is 
high during the first year with more male Mohave ground squirrels lost 
than females. Female Mohave ground squirrels can breed at 1 year of age 
if environmental conditions are favorable (Leitner and Leitner 1998, p. 
28).
    The reproductive success of the Mohave ground squirrel is dependent 
on the amount of fall and winter precipitation. Leitner and Leitner 
(1998, p. 20) found a positive correlation between fall and winter 
rainfall and recruitment of juvenile squirrels the following year. In a 
low rainfall year, Mohave ground squirrels may forego breeding, or the 
low availability of food due to low rainfall may cause reproductive 
failure (Leitner and Leitner 1998, p. 29).
Range and Distribution
    The presumed historical range of the Mohave ground squirrel, which 
is based on the current range and historical locations of suitable 
habitat, is the northwest portion of the Mojave Desert in parts of 
Inyo, Kern, Los Angeles, and San Bernardino Counties, California. This 
area is bounded on the south and west by the San Gabriel, Tehachapi, 
and Sierra Nevada ranges, and on the northeast by the Owens Lake and 
Coso, Slate, Quail, Granite, and Avawatz Mountains. The southeastern 
edge of the historical range is bordered by the Mojave River with the 
exception of one locality east of the Mojave River in the Lucerne 
Valley. The historical range of the Mohave ground squirrel is assumed 
to have included that area of the Antelope Valley west of the 
communities of Palmdale, Lancaster, Rosamond, and Mojave, although 
there are no records of the species being sighted or captured there.
    The current range of the Mohave ground squirrel is similar to the 
historical range, except it excludes the western portion of the 
Antelope Valley in Los Angeles and Kern Counties and possibly some of 
the area from Victorville to the south and southeast to Lucerne Valley 
in San Bernardino County. Urban and agricultural development in these 
areas has resulted in the loss or modification of Mohave ground 
squirrel habitat. The Mohave ground squirrel has the smallest range of 
any ground squirrel species in the United States. Gustafson (1993, p. 
8) states the geographic range of the Mohave ground squirrel 
encompasses approximately 1,968,000 hectares (ha) (4,863,000 acres 
(ac)).
Activity Patterns, Movements, and Home Range
    The active season for the Mohave ground squirrel is short, 
generally from early March to August (Bartholomew and Hudson 1960, p. 
194), but may begin as early as mid-January to late February. 
Initiation depends on temperature and elevation (Gustafson 1993, p. 
19). During this time, Mohave ground squirrels must mate, gather enough 
nutrition to produce and sustain a litter, and ensure nutritional 
reserves to last during the inactive season. During the inactive 
season, Mohave ground squirrels exist in their burrows in a state of 
torpor (a state of reduced physiological activity or sluggishness) to 
conserve their reserves of energy and water.
    The length of the active season varies by sex, age, and 
availability of food resources. In dry years, which are often non-
reproductive years, Mohave ground squirrels may enter their state of 
torpor as early as spring (Leitner et al. 1995, p. 83). The active 
season for an adult is shorter than for a juvenile as adults do not 
need to acquire as much energy for the inactive season as juveniles do. 
The active season for an adult female is generally longer than for a 
male because females need to acquire additional energy for litter 
production and lactation (Leitner et al. 1997, pp. 114-115).

[[Page 22066]]

    Mohave ground squirrels are diurnal; they spend much of the day 
above ground (Recht 1977, p. 56). As temperatures increase into the 
spring and early summer, Mohave ground squirrels will spend more time 
in the shade of shrubs or briefly use their burrows. Burrows are 
usually located beneath large shrubs. Mohave ground squirrels may use 
several burrows at night throughout a season; they also use other 
burrows for predator avoidance and temperature regulation. The burrow 
used for the inactive season is dug specifically for that period (Recht 
1977, p. 9).
    Mohave ground squirrels exhibit a behavior called natal dispersal. 
Upon dispersing from the burrow where they were born, some males will 
move and take up residence at least 1,009 meters (m) (3,280 feet (ft)) 
from the natal burrow while females move a shorter distance of 200 to 
300 m (650 to 980 ft) from their natal burrows (Leitner and Leitner 
1998, p. 34; Harris and Leitner 2005, p. 191).
    The home range of the Mohave ground squirrel varies among years and 
between sexes during the mating season. The mean home range is 0.74 ha 
(1.83 ac) for mating females and 6.73 ha (16.63 ac) for males. Outside 
the breeding season, the mean home range size is 1.20 ha (2.96 ac) for 
females and 1.24 ha (3.06 ac) for males (Harris and Leitner 2004, pp. 
520-521).
Population Demographics
    The behavioral characteristics of the Mohave ground squirrel, as 
discussed above, make it difficult to determine or estimate population 
status and trends because the species spends much of the year 
underground and populations appear to be sensitive to both seasonal and 
annual rainfall patterns. That is, in dry years or dry fall seasons, 
reproduction during the following spring season may be unsuccessful and 
population size may contract (Leitner and Leitner 1998, pp. 29-31).
    Survey results suggest that the Mohave ground squirrel has a patchy 
distribution throughout its range (Hoyt 1972, p. 7; Gustafson 1993, p. 
viii). Most reported information describes the number of animals 
trapped or number trapped as compared to the trapping effort. We are 
aware of only one location where information on population trend was 
available (Leitner 2005, p. 3). In the northwest portion of the range 
of the Mohave ground squirrel, trapping results are available for the 
Coso Range within China Lake Naval Air Weapons Station (NAWS). The 
surveys span 1992 to 1996 and 2001 to 2005. The total number of Mohave 
ground squirrels captured during the first survey period was more than 
twice that of the second (Leitner 2005, p. 3).
    Brooks and Matchett (2002) analyzed the data from all known Mohave 
ground squirrel studies. Forty-nine percent of the sites were 
identified from observing or trapping only one animal.
Habitat and Life History Requirements
    The habitat requirements of the Mohave ground squirrel are varied. 
The species has been found in a variety of vegetative communities 
including Mojave Creosote Scrub, Desert Saltbush Scrub, Desert Sink 
Scrub, Desert Greasewood Scrub, Shadscale Scrub, and Joshua Tree (Yucca 
brevifolia) Woodland (Gustafson 1993, pp. ix, 81). Creosote Bush Scrub 
is the vegetation community in which the Mohave ground squirrel is most 
often found. Mohave ground squirrels usually inhabit flat to moderately 
sloping terrain. They prefer deep rather than shallow soils and 
gravelly soils rather than sandy soils (Aardahl and Roush 1985, p. 23). 
Soil characteristics are important as the Mohave ground squirrel 
constructs burrows for temperature regulation, predator avoidance, and 
inactive season use.
    The food habits of the Mohave ground squirrel are diverse. Recht 
(1977, p. 80) called the Mohave ground squirrel a facultative 
specialist; its foraging strategy falls between that of a specialist 
and a generalist. The Mohave ground squirrel specializes in foraging on 
certain plant species over short periods of time. As the availability 
of forage species changes throughout the active season, the Mohave 
ground squirrel adapts its foraging strategy to maximize energy intake 
in a changing environment. Observations and fecal analysis indicate 
that Mohave ground squirrels consume a variety of annual and perennial 
plants and arthropods (Leitner and Leitner 1992, p. 12; Gustafson 1993, 
pp. 77-83). At one study site, the leaves of three shrub species made 
up 60 percent of the Mohave ground squirrel diet based on fecal 
analysis (Leitner and Leitner 1998, p. 34). In a study by Leitner and 
Leitner (1992) in the northern part of its range, the Mohave ground 
squirrel was found to consume leaves of annual and perennial plants, 
their fruits and seeds, fungi, and butterfly larvae. Mohave ground 
squirrels appear to exploit food sources that are available on an 
intermittent basis. They may also select particular food items over 
others because of higher water content. Leitner and Leitner (1992, p. 
25) concluded that the Mohave ground squirrel is flexible in exploiting 
high-quality food resources.
Predation and Mortality
    There is little documentation on the natural predators of the 
Mohave ground squirrel. There is circumstantial evidence of predation 
by coyotes (Canis latrans), prairie falcons (Falco mexicanus), and 
common ravens (Corvus corax) (Leitner et al. 1997, p. 49; J. Harris, 
personal communication, as cited in the petition, p. 15). There may be 
other natural predators of the Mohave ground squirrel.
    Mortality is high for the Mohave ground squirrel during the first 
year and appears to be skewed toward males (Brylski et al. 1994, p. 64; 
Leitner and Leitner 1998, p. 28). Mortality may also be caused by 
extended periods of low amounts of fall and winter rainfall, which 
results in reduced availability of forage and water, and can increase 
vulnerability to disease.

Evaluation of Information for This Finding

    Section 4 of the Act (16 U.S.C. 1533), and implementing regulations 
at 50 CFR 424, set forth the procedures for adding species to, or 
removing a species from, 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 the Mohave ground squirrel, as presented in the petition and 
other information available in our files, is substantial, thereby 
indicating that the petitioned action may be warranted. Our evaluation 
of this information is presented below.

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

Evaluation of Information Provided in the Petition and Available in 
Service Files

    The petitioners presented information regarding threats to the 
Mohave ground squirrel from reduced range and habitat destruction, 
including: urban and rural

[[Page 22067]]

development on private and public lands; agricultural development; 
military activities; livestock grazing; transportation; energy 
development; and that the cumulative impacts of drought, habitat 
destruction, habitat fragmentation, and decrease in precipitation with 
climate change pose a threat greater than the drought episodes to which 
the Mohave ground squirrel is adapted.
    The range of the Mohave ground squirrel is the smallest of all 
ground squirrels in the United States. Based on information provided by 
the petitioners, the Mohave ground squirrel appears to have been nearly 
extirpated from the southern portion of its range, which represents 
approximately 20 percent of its range (Leitner as cited in the 
petition, p. 8). This assertion is based on the results of surveys 
conducted for the Mohave ground squirrel from 2002 to 2004 (Leitner 
2004 as cited in the petition, p. 17). The portion of the recently 
reduced range includes an area south of State Highway 58 in the 
Palmdale-Lancaster area and the Victorville to Lucerne Valley area.
Private Lands
    On private lands, which comprise about 31 percent of the current 
range of the Mohave ground squirrel, the petitioners claim 2.8 percent 
of the range of the Mohave ground squirrel has been lost to urban and 
rural development and approximately 2 percent (37,000 ha (92,000 ac)) 
to agricultural fields. The information on impacts to the Mohave ground 
squirrel from agricultural development was derived from Hoyt (1972, p. 
8), Aardahl and Roush (1985, p. 2), and Gustafson (1993, pp. 23-24). 
The petitioners also stated that they have no updated data to quantify 
the extent or intensity of this threat. We have no information in our 
files to dispute the figures presented by the petitioners; however, we 
currently do not have information to determine whether a 2.8 percent 
loss to urban and rural development and a 2 percent loss to 
agricultural development is biologically significant to the Mohave 
ground squirrel.
Public Lands
    Public lands managed by the Bureau of Land Management (BLM) account 
for about 31.8 percent of the species' range. The petitioners stated 
that BLM's land management plan for the West Mojave Desert (West Mojave 
Plan) would allow new development throughout much of the range of the 
Mohave ground squirrel and would not protect the four Mohave ground 
squirrel ``core areas'' (see petition, p. 17). ``Core areas'' are 
defined by the petitioners as locations where Mohave ground squirrels 
have been reliably captured over time, or where there are thriving 
populations. The petitioners stated that activities that result in the 
loss of habitat in these ``core areas'' or prevent dispersal among 
these ``core areas'' will impede and eventually prohibit conservation 
of the Mohave ground squirrel.
    Public land managed by the Department of Defense accounts for about 
34.5 percent of the species' current range. The petitioners stated that 
current military training at Fort Irwin threatens Mohave ground 
squirrels by crushing animals, compacting and otherwise disturbing 
soils, collapsing burrows, destroying shrubs used for cover, and 
reducing spring annual plants used by Mohave ground squirrels for 
forage (Bury et al. 1977, pp. 16, 18). According to the petitioners, 
Fort Irwin's training currently affects 7.4 percent of the range of the 
Mohave ground squirrel, and the proposed expansion of Fort Irwin will 
affect additional lands within the range of the Mohave ground squirrel 
and will fragment one of the four Mohave ground squirrel ``core areas'' 
as identified by the petitioners.
    Additionally, 2.7 percent of the current range of the Mohave ground 
squirrel occurs on other public `protected lands' (see petition, p. 40) 
including; federally designated wilderness areas, State park land, 
California Department of Fish and Game land, and the Desert Tortoise 
Natural Area.
Livestock Grazing
    The petitioners stated that livestock grazing has the potential to 
degrade Mohave ground squirrel habitat through changes in soil 
structure, including accelerated erosion and collapsing burrows, 
changes in vegetative structure, reduced availability of native forage 
species (Laabs 2002, p. 5; Campbell 1988, pp. 569, 574), and direct 
competition with Mohave ground squirrels for limited quality and 
quantity of forage (Leitner and Leitner 1998; pp. 29, A6, A7, A15, and 
A23). According to the petitioners' GIS analysis, 27 percent of the 
range of the Mohave ground squirrel has been impacted by livestock 
grazing.
    Aardahl and Roush (1985, p. 23), as cited in the petition, stated 
that ``land uses which affect the availability of forbs and grasses 
have the potential to influence the long-term population of the Mohave 
ground squirrel,'' but this does not ``mean that properly managed 
livestock grazing will cause a significant negative impact on the 
Mohave ground squirrel.'' Twenty-one of 22 study sites surveyed were 
grazed by sheep or cattle in varying degrees; the study site with the 
highest total adjusted captures of Mohave ground squirrels showed 
considerable signs of grazing (Aardahl and Roush 1985, p. 23). The 
petitioners did not provide information, and we have no information in 
our files, on the extent or magnitude of the impacts of livestock 
grazing on the Mohave ground squirrel.
Transportation
    The petitioners identified the extensive network of highways and 
roads in the range of the Mohave ground squirrel as a threat. The 
petitioners claim impacts from highway and road establishment and 
vehicle use include habitat loss, fragmentation, and degradation, and 
direct mortality from vehicle strikes (Gustafson 1993, pp. 23, 26; BLM 
2003, p. 30; Leitner as cited in the petition, p. 22). The petitioners 
stated that there is evidence of surface disturbance to roadsides up to 
400 m (1,312 ft) away from the road, and that 37 percent of transects 
conducted by the BLM in the West Mojave Desert were bisected by roads. 
The petitioners calculated that the total area of the network of roads 
and highways affected 65,964 ha (163,000 ac) or 3.3 percent of the 
range of the Mohave ground squirrel. The petitioners provided 
additional information that impacts from roads on the desert tortoise 
have been documented more than 3,962 m (13,000 ft) from the highest 
level traffic road (Hoff and Marlow 2002, p. 454) and that similar 
impacts likely occur to the Mohave ground squirrel.
    We do not agree that impacts to the desert tortoise from roads that 
have been measured more than 3,962 m (13,000 ft) from the highest 
traffic roads are the same as those to the Mohave ground squirrel. The 
Hoff and Marlow study (2002, p. 454) reported on the abundance of 
desert tortoise sign at intervals from roads. This study was specific 
to the desert tortoise. It did not examine the effects of roads on the 
Mohave ground squirrel. Therefore, any application of the results from 
this research to the Mohave ground squirrel is inferred and is not 
supported by the data. However, we agree with the petitioners that 
roads and highways result in direct mortality to Mohave grounds 
squirrels from vehicle collisions and habitat loss and degradation.
Energy Development
    According to the petitioners, geothermal exploration and 
development and the construction of

[[Page 22068]]

solar energy plants in the range of the Mohave ground squirrel have 
caused, and will likely cause, adverse impacts to the Mohave ground 
squirrel and loss or degradation of habitat (Leitner and Leitner 1989, 
p. 2). The petitioners did not quantify the amount of habitat affected. 
We acknowledge that energy development for geothermal and solar energy 
has occurred within the range of the Mohave ground squirrel and that 
this development can result in the degradation or loss of habitat used 
by the Mohave ground squirrel. The petitioners do not provide 
information, and we do not have information in our files, on the extent 
of this loss or degradation and how it will affect the conservation of 
the Mohave ground squirrel.
Cumulative Impacts of Habitat Destruction, Fragmentation, and Decreased 
Precipitation
    The petitioners provided information that indicates the 
reproduction and survival of the Mohave ground squirrel is ultimately 
linked to rainfall (Harris and Leitner 2004, pp. 517, 518). Mohave 
ground squirrels may fail to persist in certain areas during drought 
episodes (Leitner and Leitner 1998, p. 31). The petitioners assert the 
cumulative impacts of habitat destruction, habitat fragmentation, and 
overall decrease in precipitation due to climate change are a greater 
threat to the Mohave ground squirrel than the periods of low rainfall 
and drought episodes with which the Mohave ground squirrel evolved.
    Based on information from the Intergovernmental Panel on Climate 
Change (Watson et al. 2002, pp. 8, 9), we acknowledge temperatures in 
southern California are likely to increase and precipitation is likely 
to decrease in the future. With hotter, drier conditions and more 
extreme weather patterns in southern California than those with which 
the Mohave ground squirrel evolved, the species may be negatively 
affected. However, we believe that climate change models that are 
currently available are not yet capable of making meaningful 
predictions of climate change for specific, local areas such as the 
range of the Mohave ground squirrel (Parmesan and Matthews 2005, p. 
354). We are not currently aware of models that predict how climate in 
the range of the Mohave ground squirrel will change, and we do not know 
how any change may alter the range of, or otherwise threaten, the 
species.

Summary of Factor A

    In summary, the petitioners presented information regarding threats 
to the Mohave ground squirrel from reduced range and habitat 
destruction, including: urban and rural development on private and 
public lands; agricultural development; military activities; livestock 
grazing; transportation; and energy development. We found the petition 
and information in our files presents substantial information that 
these activities may have contributed to a recent range contraction in 
the southern portion of the Mohave ground squirrel's range, and may 
threaten the Mohave ground squirrel across its current range by 
removing shrubs needed for cover and forage, disturbing soil, or 
removing or degrading other habitat features necessary for Mohave 
ground squirrel life history requirements. Additionally, one or more of 
these activities may threaten what the petitioners identify as ``core 
areas'' for the Mohave ground squirrel by removing habitat, fragmenting 
the habitat, and preventing dispersal among the ``core areas.'' 
However, we determined the petition does not present substantial 
information indicating that climate change may be a threat to the 
species. Additionally, information on the subject of climate change in 
our files is not specific to the Mohave ground squirrel. We will 
evaluate the effects of climate change, including reduced precipitation 
and any cumulative effects of habitat fragmentation or loss on the 
Mohave ground squirrel, when we conduct our status review.
    On the basis of our evaluation of the information in the petition 
and information in our files, we determined that the petition presents 
substantial information indicating that listing the Mohave ground 
squirrel as endangered may be warranted due to destruction, 
modification, or curtailment of the species' habitat or range.

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

    The petitioners did not provide information or list any threats to 
the Mohave ground squirrel from overutilization for commercial, 
recreational, or educational purposes. The petitioners stated that the 
utilization of the Mohave ground squirrel for scientific purposes is 
strictly controlled by the California Department of Fish and Game.

Summary of Factor B

    On the basis of our evaluation, we determined that the petition 
does not present substantial information indicating that listing the 
Mohave ground squirrel as endangered may be warranted due to the 
overutilization for commercial, recreational, scientific, or 
educational purposes. Additionally, we do not have substantial 
information in our files to suggest that overutilization for 
commercial, recreational, scientific, or educational purposes may 
threaten the Mohave ground squirrel. However, we will evaluate all 
factors, including threats from overutilization for commercial, 
recreational, scientific, or educational purposes, when we conduct our 
status review.

C. Disease or Predation

Evaluation of Information Provided in the Petition and Available in 
Service Files

    The petitioners did not provide information or list any threat to 
the Mohave ground squirrel from disease, and we do not have information 
in our files regarding potential threats to this species due to 
disease.
    The petitioners stated that there is little documentation of the 
Mohave ground squirrel's natural predators, but claimed that predation 
by coyotes, common ravens, house cats, domestic dogs, and feral dogs is 
a concern. Although the petitioners stated that cats prey on small 
mammals and dogs dig up rodent burrows, they did not present any 
information on the level of mortality or population impacts from 
predation for Mohave ground squirrels, any other ground squirrel 
species, or any small mammal species. The petitioners noted that the 
numbers of common ravens and coyotes, known predators of the Mohave 
ground squirrel, have increased, posing an increased predation risk to 
Mohave ground squirrel populations. However, there is no information 
provided that the numbers of cats, dogs, common ravens, or coyotes have 
increased in the range of the Mohave ground squirrel, and there is no 
evidence to indicate that there is increased predation by these 
predators on the Mohave ground squirrel. We do not have information in 
our files to indicate that predation is a threat to the survival of the 
Mohave ground squirrel.

Summary of Factor C

    On the basis of our evaluation, we determined that the petition 
does not present substantial information indicating that listing the 
Mohave ground squirrel as endangered may be warranted due to disease or 
predation. Additionally, we do not have substantial information in our 
files to suggest that disease or predation threaten the Mohave ground 
squirrel. However, we will evaluate all factors, including threats from 
disease and

[[Page 22069]]

predation, when we conduct our status review.

D. The Inadequacy of Existing Regulatory Mechanisms

Evaluation of Information Provided in the Petition and Available in 
Service Files

    The petitioners stated that current regulations have proven 
inadequate to conserve the Mohave ground squirrel; that only 9 percent 
of the range of the Mohave ground squirrel has any kind of protected 
status; and that, although the Mohave ground squirrel is a State-listed 
species, this listing provides no conservation assurances for the 
Mohave ground squirrel on Federal lands.
    The California Endangered Species Act provides protection for the 
Mohave ground squirrel on private and State-owned land, and on Federal 
lands in relation to activities carried out by non-Federal entities 
that are required to obtain a State permit or authorization.
    The major military installations within the range of the Mohave 
ground squirrel have implemented Integrated Natural Resources 
Management Plans that cover the Mohave ground squirrel and implement 
actions to manage for the species. In their management plan for the 
West Mojave Desert, the BLM considers the Mohave ground squirrel an 
umbrella species, a species whose habitat requirements include those of 
many other species and whose conservation should automatically conserve 
a host of other species. BLM has implemented a plan that establishes a 
Mohave ground squirrel Conservation Area that contains 35 percent of 
the species' historical range on BLM land.

Summary of Factor D

    On the basis of our evaluation, we determined that the petition 
does not present substantial information indicating that listing the 
Mohave ground squirrel as endangered may be warranted due to the 
inadequacy of existing regulatory mechanisms. Additionally, we do not 
have substantial information in our files to suggest that existing 
regulatory mechanisms are inadequate and thus threaten the Mohave 
ground squirrel. However, we will evaluate all factors, including 
threats from the inadequacy of existing regulatory mechanisms, when we 
conduct our status review.

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

Evaluation of Information Provided in the Petition and Available in 
Service Files

    The petitioners stated that pesticide use may adversely affect the 
Mohave ground squirrel. According to the petitioners, Mohave ground 
squirrels live in native vegetative communities adjacent to 
agricultural fields and other areas where rodenticides are used. Mohave 
ground squirrels use these areas for forage and shelter. The 
petitioners claim that if rodenticides are used on agricultural fields, 
Mohave ground squirrels could be adversely affected, or they could be 
exterminated by the State Rodent Program. In the early part of the 20th 
century, the Los Angeles Agricultural Commission used poison grain to 
target and eliminate ground squirrels in the Antelope Valley, which 
includes the historical range of the Mohave ground squirrel.
    Although we are aware that rodenticides, such as those that include 
strychnine as the active ingredient, may be used to kill ground 
squirrels, there is no information in the petition or our files to 
indicate that rodenticides are used to specifically target Mohave 
ground squirrels or that any rodenticides currently used within the 
range of the Mohave ground squirrel are adversely affecting the status 
of this species.

Summary of Factor E

    On the basis of our evaluation, we determined that the petition 
does not present substantial information indicating that listing the 
Mohave ground squirrel as endangered may be warranted due to other 
natural or manmade factors affecting its continued existence. 
Additionally, we do not have substantial information in our files to 
suggest that other natural or manmade factors threaten the Mohave 
ground squirrel. However, we will evaluate all factors, including 
threats from other natural or manmade factors affecting its continued 
existence, when we conduct our status review.

Finding

    The petition and supporting information have identified numerous 
factors affecting the Mohave ground squirrel, including: reduced range, 
urban and rural development, agricultural development, military 
activities, livestock grazing, transportation and energy development, 
and cumulative impacts of habitat destruction, fragmentation, and 
decreased precipitation (Factor A); predation (Factor C); the lack of 
regulatory mechanisms protecting the species and its habitat (Factor 
D); and pesticide use (Factor E).
    On the basis of our evaluation under section 4(b)(3)(A) of the Act, 
we have determined that the petition presents substantial scientific or 
commercial information indicating that listing the Mohave ground 
squirrel as endangered may be warranted. This finding is based on 
information provided by the petitioners and in our files for Factor A. 
In particular, there is substantial information to indicate habitat 
based threats under Factor A may remove shrubs needed for cover and 
forage, disturb soil, or remove or degrade other habitat features 
necessary for Mohave ground squirrel life history requirements across 
its current range. The information provided by the petitioners and in 
our files for Factors B, C, D, and E was not substantial. In 
considering what factors might constitute threats, we must look beyond 
the mere exposure of the species to the factor to determine whether the 
species responds to the factor in a way that causes actual impacts to 
the species. If there is exposure to a factor, but no response, or only 
a positive response, that factor is not a threat. If there is exposure 
and the species responds negatively, the factor may be a threat and we 
then attempt to determine how significant a threat it is. If the threat 
is significant, it may drive or contribute to the risk of extinction of 
the species such that the species may warrant listing as threatened or 
endangered as those terms are defined by the Act. This does not 
necessarily require empirical proof of a threat. The combination of 
exposure and some corroborating evidence of how the species is likely 
impacted could suffice. The mere identification of factors that could 
impact a species negatively may not be sufficient to compel a finding 
that listing may be warranted. The information shall contain evidence 
sufficient to suggest that these factors may be operative threats that 
act on the species to the point that the species may meet the 
definition of threatened or endangered under the Act.
    Because we have found that the petition presents substantial 
information that listing the Mohave ground squirrel may be warranted, 
we are initiating a status review to determine whether listing the 
Mohave ground squirrel under the Act is warranted. We will issue a 12-
month finding as to whether the petitioned action is warranted.
    The ``substantial information'' standard for a 90-day finding 
differs

[[Page 22070]]

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 also requested that we designate critical habitat 
for the Mohave ground squirrel. If we determine in our 12-month finding 
that listing the Mohave ground squirrel is warranted, we will address 
the designation of critical habitat at the time of the proposed 
rulemaking.

References Cited

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

Author

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

Authority

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

    Dated: April 12, 2010
Signed: Daniel M. Ashe
Deputy Director, U.S. Fish and Wildlife Service
[FR Doc. 2010-9377 Filed 4-26-10; 8:45 am]
BILLING CODE 4310-55-S