[Federal Register Volume 76, Number 194 (Thursday, October 6, 2011)]
[Proposed Rules]
[Pages 62214-62258]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-25473]
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Vol. 76
Thursday,
No. 194
October 6, 2011
Part III
Department of the Interior
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Fish and Wildlife Service
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50 CFR Part 17
Endangered and Threatened Wildlife and Plants; 12-Month Finding on a
Petition To List the Mohave Ground Squirrel as Endangered or
Threatened; Proposed Rule
Federal Register / Vol. 76 , No. 194 / Thursday, October 6, 2011 /
Proposed Rules
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R8-ES-2010-0006; 92210-1111-0000-B2]
Endangered and Threatened Wildlife and Plants; 12-Month Finding
on a Petition To List the Mohave Ground Squirrel as Endangered or
Threatened
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notice of 12-month petition finding.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a
12-month finding on a petition to list the Mohave ground squirrel
(Spermophilus mohavensis) as endangered or threatened under the
Endangered Species Act of 1973, as amended (Act). After review of the
best available scientific and commercial information, we find that
listing the Mohave ground squirrel is not warranted at this time.
However, we ask the public to continue to submit to us any new
information that becomes available concerning the threats to the Mohave
ground squirrel or its habitat at any time.
DATES: The finding announced in this document was made on October 6,
2011.
ADDRESSES: This finding is available on the Internet at http://www.regulations.gov at Docket Number FWS-R8-ES-2010-0006 and at http://www.fws.gov/ventura/. Supporting documentation we used in preparing
this finding is available for public inspection, by appointment, during
normal business hours at the U.S. Fish and Wildlife Service, Ventura
Fish and Wildlife Office, 2493 Portola Road, Suite B, Ventura, CA
93003. Please submit any new information, materials, comments, or
questions concerning this finding to the above address.
FOR FURTHER INFORMATION CONTACT: Michael McCrary, Listing and Recovery
Program Coordinator, U.S. Fish and Wildlife Service, Ventura Fish and
Wildlife Office (see ADDRESSES); by telephone at 805-644-1766; or by
facsimile at 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:
Background
Section 4(b)(3)(B) of the Act (16 U.S.C. 1531 et seq.) requires
that, for any petition to revise the Federal Lists of Endangered and
Threatened Wildlife and Plants that contains substantial scientific or
commercial information that listing may be warranted, we make a finding
within 12 months of the date of receipt of the petition. In this
finding, we determine whether the petitioned action is: (a) Not
warranted, (b) warranted, or (c) warranted, but the immediate proposal
of a regulation implementing the petitioned action is precluded by
other pending proposals to determine whether species are endangered or
threatened, and expeditious progress is being made to add or remove
qualified species from the Federal Lists of Endangered and Threatened
Wildlife and Plants. Section 4(b)(3)(C) of the Act requires that we
treat a petition for which the requested action is found to be
warranted but precluded as though resubmitted on the date of such
finding, that is, requiring a subsequent finding to be made within 12
months. We must publish these 12-month findings in the Federal
Register.
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 list the
Mohave ground squirrel as a threatened species. At that time, the
species was a category 2 candidate (November 15, 1994; 59 FR 58982),
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).
On September 5, 2005, we received a petition, dated August 30,
2005, from the Defenders of Wildlife and Dr. Glenn R. Stewart to list
the Mohave ground squirrel as an endangered species in accordance with
section 4 of the Act. It also requested that critical habitat be
designated concurrent with the listing of the Mohave ground squirrel.
The petition clearly identified itself as such and included the
requisite identification information for the petitioners, as required
in 50 CFR 424.14(a).
On April 27, 2010, the Service made its 90-day finding (75 FR
22063), concluding that the petition presented substantial scientific
or commercial information to indicate that listing the Mohave ground
squirrel may be warranted, announced the initiation of a status review
of this species, and solicited comments and information to be provided
in connection with the status review by June 28, 2010. This notice
constitutes our 12-month finding regarding the petition to list the
Mohave ground squirrel.
Species Information
Species Description
The Mohave ground squirrel is a medium-sized squirrel. Total
length, including the tail, is about 9 inches (in) (23 centimeters
(cm)), tail length is about 2.5 in (6.4 cm), and weight is about 3.5
ounces (104 grams). The upper body is grayish brown, pinkish gray,
cinnamon gray, and pinkish cinnamon, without stripes or fleckings. The
underparts of the body and the tail are silvery white and the tail is
bushy (Grinnell and Dixon 1918, p. 667). The skin is darkly pigmented
and dorsal hair tips are multi-banded. The Mohave ground squirrel has a
winter and summer pelage (coat). In summer the pelage is coarser and
shorter, the sides of the face paler, and the underbelly whiter than
the winter pelage. The two sexes appear to be alike in color and
measurements (Grinnell and Dixon 1918, p. 667).
Two other species of small ground squirrels occur within the range
of the Mohave ground squirrel, the antelope ground squirrel
(Ammospermophilus leucurus) and the round-tailed ground squirrel
(Xerospermophilus tereticaudus). The three species are different in
appearance. Although similar in size to the Mohave ground squirrel, the
antelope ground squirrel is grayish brown in color, with a white side
stripe and a black band on the underside of the tail near the tip
(Ingles 1965, pp. 169-171). The round-tailed ground squirrel has a
unicolored tail that is cylindrical or round and not bushy, and a
larger body than the Mohave ground squirrel (Ingles 1965, p. 171).
However, its skull is significantly smaller than that of the Mohave
ground squirrel in 18 of 20 cranial characteristics (Best 1995, p.
508). Mohave and antelope ground squirrels occur sympatrically
(occupying the same or overlapping geographic areas without
interbreeding) in the same habitat (Aardahl and Roush 1985, p. 20),
while round-tailed ground squirrels overlap only along the eastern edge
of the Mohave ground squirrel's range (see ``Nomenclature and
Taxonomy'' section below).
[[Page 62215]]
Nomenclature and Taxonomy
The scientific name of the Mohave ground squirrel was changed from
Spermophilus mohavensis to Xerospermophilus mohavensis with the
publication of a review of the available research on morphological,
genetic, cytogenetic, ecological, and behavioral attributes in the
genus Spermophilus (Helgen et al. 2009, p. 273).
The Mohave ground squirrel is a distinct, full species with no
recognized subspecies. It was discovered in 1886 by Frank Stephens
(Grinnell and Dixon 1918, p. 667) and described by Merriam (1889, p.
15). The type specimen is from near Rabbit Springs, San Bernardino
County, California, about 15 miles (mi) (24.1 kilometers (km)) east of
Hesperia (Grinnell and Dixon 1918, p. 667).
The closest relative of the Mohave ground squirrel is the round-
tailed ground squirrel (Bell et al. 2009, p. 5; Helgen et al. 2009, p.
293). Until 1977, the ranges of these two species were thought to be
adjacent to each other but not overlapping (Hall and Kelson 1959, p.
358). However, Wessman (1977, p. 10) determined that the eastern edge
of the geographic range of the Mohave ground squirrel overlapped the
western edge of the round-tailed ground squirrel (Wessman 1977, pp. 12-
13). He identified several areas of contact between the two species and
identified one area near Helendale, San Bernardino County, California,
as a possible zone of hybridization between the species. He observed
morphological characteristics of both species exhibited in a few of the
squirrels captured there (e.g., long, narrow tail with white on the
underside) (Wessman 1977, p. 13). However, in 2009, Bell et al. (p. 11)
found no evidence of mitochondrial DNA introgression between the Mohave
ground squirrel and the round-tailed ground squirrel, including the
three individuals identified as backcross individuals based on allozyme
(form of an enzyme that differs in amino acid sequence) and karyotypic
(the shape, type, number, and order of a species' chromosomes) data
from Hafner and Yates (1983). We are not aware of any information that
would indicate hybridization occurs with the sympatric antelope ground
squirrel.
Range and Distribution
The Mohave ground squirrel is endemic to the western part of the
Mojave Desert, in portions of Inyo, Kern, Los Angeles, and San
Bernardino Counties, California. It has one of the smallest ranges of
any species of ground squirrel in North America (Hoyt 1972, p. 3). We
define range as the geographical area within which a species may be
found.
Aspects of the Mohave ground squirrel's biology and behavior make
individuals of the species difficult to observe, trap, and count, which
in part explains why the range of the species has increased over time
(see below). Mohave ground squirrels are only active and above ground
for part of the year (generally February through August) and therefore
can only be trapped and observed during this time. They spend much of
the year underground and in a state of dormancy (see ``Active Season
and Dormancy'' section). The length of the active season and movements
of Mohave ground squirrels may also be affected by rainfall amounts.
The number of individuals in an area appears to decline during dry
years, and movements and home range size shrink (Harris and Leitner
2004, p. 521). Thus, if traps are set during a dry year, the reduced
movements of Mohave ground squirrels and reduced densities or local
extirpations make it less likely that the traps are located when and
where they will capture Mohave ground squirrels. Conversely, if traps
are set during a wet year when home ranges are larger, the Mohave
ground squirrel may avoid the baited traps because of the increased
availability of forage.
Because most surveys for the Mohave ground squirrel have been only
1 year in duration, this limited survey duration makes it difficult to
assess population trend for a species whose numbers, movements, and
``trapability'' can fluctuate greatly among years (Brooks and Matchett
2002, p. 171). These factors in combination have made it difficult to
determine the boundaries of the species' range, its distribution within
the range, and population trends (see ``Abundance and Trends''
section). This has been further complicated because the vast majority
of the information currently available on the distribution and
abundance of Mohave ground squirrels is based on the California
Department of Fish and Game (CDFG) survey protocol, which has been
known to not detect squirrels when other methods have shown them to be
present (see ``Abundance and Trend'' section below).
In 1938, Howell (1938, p. 184) published a map of the range of the
Mohave ground squirrel that included the western Antelope Valley to an
area 15 mi (25.2 km) west of Barstow. In 1977, Wessman surveyed for the
Mohave ground squirrel along much of its eastern boundary and found the
species' range extended 1,152,000 ac (466,200 ha) farther east and
south than previously reported (Wessman 1977, p. 4).
For this 12-month finding, the Service is defining the range of the
Mohave ground squirrel as about 5,319,000 acres (ac) (2,152,532
hectares (ha)) (Service calculations) (see Map 1). The range is bounded
on the south and west by the San Bernardino, San Gabriel, Tehachapi,
and Sierra Nevada mountain ranges, although the species occurs in
canyons in the eastern foothills of the Sierra Nevada up to 5,600 feet
(ft) (1,706 meters (m)) (Gustafson 1993, pp. 56-57; Laabs 1998, p. 1).
The range is bounded on the north and east by Owens Lake and the Mojave
River/Lucerne Valley, respectively (Leitner 2008, p. 18). Howell (1938,
p. 184) and Aardahl and Roush (1985, p. 3) included the Antelope Valley
west of Palmdale and Lancaster in the range of the Mohave ground
squirrel (see Map 1).
The range map in the petition did not include the western Antelope
Valley because there are no definite records of the species in that
area. However, for several reasons, we included the western Antelope
Valley in our range of the Mohave ground squirrel. First, older reports
and scientific papers on the Mohave ground squirrel included this area
in the range of the species (e.g., Howell 1938, p. 184; Aardahl and
Roush 1985, p. 3). Second, although portions of this area are now used
for agriculture and livestock grazing, suitable habitat still remains
and may be connected to currently occupied habitat to the east. Third,
early museum collections of the Mohave ground squirrel did not record
precise locality data and often used the closest town for reference
such as ``near Palmdale.'' Frequently, the closest town was several
miles away and the locality information vague. Fourth, recent visual
observations of Mohave ground squirrels occurred southwest of Mojave
(see Map 1) (Leitner 2008, p. 7). Thus, there is some indication that
the Mohave ground squirrel may have occurred, and may continue to
occur, in the western portion of the Antelope Valley. Although areas of
natural habitat within the range of the Mohave ground squirrel have
been lost or degraded from human activity (see Factor A), the boundary
of the current range is larger than reported by Howell in 1938.
The range of the Mohave ground squirrel may be larger than defined
by the Service, as there have been recent sightings beyond the area
defined by the Service as the range of the Mohave ground squirrel.
Although the Mohave ground squirrel has previously been reported at
elevations up to 5,600 ft (1,706 m) in the canyons in the eastern
foothills of the Sierra Nevada that open
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to the Mojave Desert (Gustafson 1993, pp. 56-57; Laabs 1998, p. 1), a
biologist recently reported a Mohave ground squirrel about 10 mi (16.1
km) south of Weldon (see Map 1) in an interior valley in the Tehachapi
Mountains (California Natural Diversity Database 2007). Another
biologist sighted a Mohave ground squirrel in the Panamint Valley,
which is about 5 mi (8 km) outside the northeastern edge of the range
(see Map 1) (Threloff 2007 in litt., p.1), whereas Aardahl
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and Roush were unsuccessful in capturing a squirrel here in 1985
(Gustafson 1993, p. 56). We are not using these two sightings in our
range calculations because they are anecdotal and fall outside the
areas previously published about the range of the Mohave ground
squirrel. Although we have not included these two sightings, they
indicate that the range of the Mohave ground squirrel may actually be
larger than previously indicated on range maps or currently defined by
the Service.
Within its range, the Mohave ground squirrel has a patchy
distribution (Hoyt 1972, p. 7), likely caused by differences in
rainfall, terrain (Zembal and Gall 1980, p. 348), elevation,
temperature (Gustafson 1993, pp. 56-57), and soils and vegetation
(Harris and Leitner 2005, p. 189). The habitat requirements of the
Mohave ground squirrel for feeding, breeding, and sheltering are not
uniformly spaced throughout its range.
Leitner (2008, pp. i-A2) collected and analyzed 1,236 unpublished
observations, field studies, and surveys from 1998 to 2007, including
both positive and negative findings of trapping efforts using the CDFG
survey protocol. These surveys were usually performed in association
with proposed development, because the Mohave ground squirrel is listed
as threatened under the California Endangered Species Act (CESA) (see
Factor D, ``State Laws and Regulations''). The survey effort has been
heavily weighted to the southernmost portion of the species' range
(Leitner 2008, p. 5), where most of the development in the range of the
Mohave ground squirrel has occurred and is occurring (see Factor A,
``Urban and Rural Development''). Approximately 67 percent of the
surveys were conducted south of State Route 58 (SR-58) (see Map 1), and
almost half of all surveys were in two areas in the southernmost part
of the range of the Mohave ground squirrel: The Lancaster-Palmdale area
and the Adelanto area. Almost all recorded observations of Mohave
ground squirrels from 1998 to 2007 have been from Edwards Air Force
Base (EAFB), which is south of SR-58 (see Map 1), or from the central
and northern portion of the squirrel's range; only a few were observed
in the southern end of the squirrel's range. However, much of the range
of the Mohave ground squirrel has not been surveyed (Leitner 2008, p.
9).
Leitner (2008, p. 10) identified four areas that he labels as
``core'' areas for the Mohave ground squirrel. ``Core'' areas have the
following criteria:
(1) The species has been present for a substantial period;
(2) The species is currently found at multiple locations; and
(3) There is a substantial number of adults representing a viable
reproductive population.
Four areas that meet the above criteria are: (1) Coso Range-
Olancha; (2) Little Dixie Wash; (3) EAFB; and (4) Coolgardie Mesa-
Superior Valley (see Map 2). Leitner (2008, p. 1) also described four
other population areas with multiple recent records of the species,
although these areas are not known to have Mohave ground squirrels
present for a substantial period: Pilot Knob, the Desert Tortoise
Natural Area-Fremont Valley, Boron-Kramer Junction, and Poison Canyon
(Leitner 2008, p. 34). Together these eight important population areas
comprise about 606,000 ac (245,240 ha), or 11.4 percent of the species'
range.
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Leitner has emphasized the importance of protecting and maintaining
connectivity between these eight areas for the conservation of the
Mohave ground squirrel (2008, p. 12). It should be noted, however, that
these areas have been identified using the data available from limited
surveys for the Mohave ground squirrel. Much of the range has not been
surveyed (Leitner 2008, p. 9); therefore, unsurveyed areas may support
additional important population areas for the Mohave ground squirrel.
As an example of a recent discovery of an important population area,
the Poison Canyon area was discovered during a 2006 survey for a
proposed drainage improvement project
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along a State highway (Sapphos 2006, p. 3-1).
Abundance and Trends
Data on population abundance and trend for the Mohave ground
squirrel are limited (Leitner 2008, p. 8). The behavioral
characteristics of the Mohave ground squirrel make it difficult to
determine its presence or abundance as it spends much of the year
underground (see ``Active Season and Dormancy'' section below). Based
on his observations, Burt (1936, p. 222) estimated the density of
Mohave ground squirrels in the southern part of their range at 15 to 20
animals per square mi (5 to 8 animals per square km). Most subsequent
studies cannot be readily compared with Burt (1936) because they did
not estimate density of animals (i.e., they either reported the number
of animals trapped or compared numbers trapped to individual trapping
efforts (Hoyt 1972, p. 6; Recht 1977, p. 4; Wessman 1977, p. 4; Leitner
1980, pp. IV-26; Aardahl and Roush 1985, pp. 11-13; Scarry et al. 1996,
pp. 12-17; Leitner 2001, pp. 13-18, 30-32).
The only location we are aware of where a population of Mohave
ground squirrels has been studied in detail for several years is in the
Coso Region in the northern portion of the species' range (Leitner
2005, p. 3). Trapping surveys for the Mohave ground squirrel at this
location were conducted from 1989 to 1996 and from 2001 to 2005.
However, the estimated population density was only reported for 1990
and for the period from 1992 to 1996 because of limited sample size in
other years (Leitner and Leitner 1998, pp. A-3, A-6, A-8, A-9, A-12, A-
15, A-18, and A-22). The number of Mohave ground squirrels that were
captured varied from year to year, ranging from 10 squirrels trapped in
2003 to 78 in 1994 (Leitner 2005, p. 3). The number of adult Mohave
ground squirrels trapped was higher per year during the period 1990-
1996 than during the period 2001-2004 (Leitner 2005, p. 3).
Researchers have suggested that trends in protocol survey data over
time could be used to evaluate the status of the species. Brooks and
Matchett (2002) analyzed the data from 19 reported studies on the
Mohave ground squirrel in 1918 and during the period 1970-2001. They
suggested that the Mohave ground squirrel may be undergoing a long-term
decline as indicated by the decreased trapping success since the mid-
1980s (Brooks and Matchett 2002, p. 176). One possible reason for
decline is that Mohave ground squirrel populations appear to be
sensitive to both seasonal and annual rainfall patterns; for example,
in dry years, reproduction the following spring may be unsuccessful,
and population numbers and the area occupied by the species may
decrease (Leitner and Leitner 1998, pp. 29-31; Harris and Leitner 2005,
p. 520).
Gustafson (1993, p. 22) reported that prolonged periods of drought
may result in the loss of Mohave ground squirrels in local areas,
because no young may be born for one up to several years, and adult
survivability is reduced by poor habitat conditions to the point where
the population dies out. In general, the population dynamics of the
Mohave ground squirrel appear to follow a contraction and expansion
pattern, i.e., there are local extirpations of squirrel populations
following drought years and recolonization of these areas with
consecutive wet years (Harris and Leitner 2005, p. 189). During the
last few decades, more consecutive years in the western Mojave Desert
have been dry versus wet (Brooks and Matchett 2002, p. 175), suggesting
a trend weighted toward extirpations rather than recolonizations.
However, Brooks and Matchett (2002, p. 176) suggest that factors other
than, or in addition to, rainfall amount and timing seem to be
affecting Mohave ground squirrel abundance, such as trapping
characteristics, trapping protocols, weather conditions, or site
(habitat) characteristics.
Leitner (2001, pp. 30-31) conducted a similar comparison of
trapping results at 11 sites in 1980, 1999, and 2000, and at 19 sites
in 2004 (Leitner 2005, p. 5). The first study showed a positive
correlation between rainfall and trapping success prior to 1991, but no
correlation after that. Both studies reported that trapping success has
declined and concluded that this indicated a possible decline in the
distribution and abundance of the Mohave ground squirrel during this
period, despite periods of above-normal precipitation (Leitner 2001, p.
32; Brooks and Matchett 2002, p. 176).
However, the survey protocol is subject to potential inaccuracies,
such as yielding false negative results or undersampling the population
(see also Factor D, ``State Laws and Regulations'' section). Mohave
ground squirrels are difficult to trap (Hoyt 1972, p. 7), and they have
been observed approaching traps but not entering them (Leitner 2009,
pers. comm.). For example, in 2009, only one Mohave ground squirrel was
trapped during two surveys conducted in the Fort Irwin western
expansion area (Delaney and Leitner 2009, p. 9). However, the detection
rate for a video detection system, which was used at the same time as
the trapping was conducted, was much higher; the video system recorded
nine Mohave ground squirrels compared to the one that was trapped
(Delaney 2009, pp. 13-14).
Food Habits
The diet of the Mohave ground squirrel consists of leaves (Recht
1977, p. 75), flowers, fruits, and seeds (Leitner and Leitner 1992, p.
12; Gustafson 1993, pp. 77-83) from a variety of plants; they also feed
on fungi (Burt 1936, p. 223) and arthropods (caterpillars) when
available (Zembal and Gall 1980, p. 345). When available in spring,
new, tender, green vegetation makes up nearly all of the diet of the
Mohave ground squirrel (Best 1995, p. 6). The Mohave ground squirrel is
also known to eat alfalfa (Best 1995, p. 5).
The Mohave ground squirrel forages on the ground, in the branches
of shrubs, and, where present, in Yucca brevifolia (Joshua trees)
(Johnson no date, p. 1). It caches food in its burrow for future use
(Johnson no date, p. 1). It obtains water from its diet, but will drink
water if available (Johnson no date, p. 1).
Recht (1977, p. 80) categorized the foraging strategy of the Mohave
ground squirrel as a facultative specialist. Because the availability
of food resources fluctuates seasonally and annually in the Mojave
Desert, the Mohave ground squirrel specializes in certain food species
for short periods, but changes the foods it consumes as their
availability changes. For example, in March 1994, the diet of the
Mohave ground squirrel in the northern part of its range was 90 percent
shrubs, 10 percent forbs (i.e., any herbaceous plant that is not grass
or grasslike), and less than 1 percent nonnative annual grasses
(Schismus and Bromus) (Leitner et al. 1995, p. 45). By April, the
Mohave ground squirrel's diet had changed to 60 percent shrubs, 35 to
40 percent forbs, and 2 percent grasses (Leitner et al. 1995, p. 48).
The quantity, variety, and nutritional quality of plant food
sources available ultimately depend on the amount of rainfall from the
preceding fall and winter (Aardahl and Roush 1985, p. 22). During
drought years, there are few-to-no herbaceous native annual forbs
available, and Mohave ground squirrels must then depend on shrub
foliage for water and nutrition (Leitner and Leitner 1998, p. 20).
This foraging strategy provides efficiency and flexibility to
maximize nutritional and water intake in a changing desert habitat
(Recht 1977, p. 80). These abilities are needed, as the Mohave ground
squirrel must increase
[[Page 62220]]
its body weight in spring and early summer to sustain itself during the
dormant period of mid-summer through winter (Leitner and Leitner 1998,
p. 33).
Reproduction
Female Mohave ground squirrels can breed at 1 year of age if
environmental conditions are favorable (Leitner and Leitner 1998, p.
28), while males do not breed until 2 years of age or older (Leitner
and Leitner 1998, p. 36).
The Mohave ground squirrel mating season occurs from mid-February
to mid-March (Harris and Leitner 2004, p. 1). Mohave ground squirrel
males typically emerge from dormancy in February, up to 2 weeks before
females (Recht pers. comm., as cited in Gustafson 1993, p. 83). Male
Mohave ground squirrels defend a territory, which females enter for
mating (Recht pers. comm., as cited in Gustafson 1993, pp. 83-84).
Three to four females mate and remain in the male's territory for a day
or so, before returning to their respective home ranges. After a
gestation period of 29 to 30 days, the young are born in the female's
burrow (natal burrow) from March to May, with a peak in April. Average
litter size is about six (Burt 1936, p. 224; Recht pers. comm., as
cited by Leitner et al. 1991, p. 63) and ranges from four to nine (Best
1995, p. 3). Parental care continues through mid-May, with juveniles
emerging above ground at 10 days to 2 weeks of age (Gustafson 1993, p.
84). By early May, the juveniles are active above ground and can be
captured in live traps.
Reproductive success appears to be strongly influenced by rainfall.
In dry years, the Mohave ground squirrel's survival strategy appears to
be to forego reproductive activity and concentrate on gaining weight
and fat reserves in the spring and early summer to better survive the
dormant period (Leitner and Leitner 1998, p. 32). For example, Mohave
ground squirrels in the Coso Range failed to reproduce successfully in
1989, 1990, and 1994, which correlated with low fall and winter
precipitation and a low standing crop of annual forbs. In each of the 3
years, precipitation during the period when it normally occurs in the
region (September 1 to March 31) was lower than the long-term average
for the same period (average of 3.3 in (8.5 cm) versus the average of 5
in (12.7 cm), respectively) (Leitner and Leitner 1998, pp. 18-19, 21,
and 29). In years when reproduction does occur, females of all age
classes (including yearlings) produce young (Leitner and Leitner 1998,
p. 28).
Mortality and Predation
Mohave ground squirrels can live up to 5 years or longer (Leitner
and Leitner 1998, p. 28). Mortality for juveniles is high during the
first year and is disproportionately higher for males than females. As
a result, the juvenile population contains significantly more females
than males, and the adult female-to-male ratio averages about 2.6:1,
but was reported to be as high as 7:1 in one population (Leitner and
Leitner 1998, p. 36).
Information on the causes of mortality in the Mohave ground
squirrel is limited. We are not aware of any information on diseases in
the species. Although not based on direct observation, predators are
believed to include coyote (Canis latrans), American badger (Taxidea
taxus), golden eagle (Aquila chrysaetos), red-tailed hawk (Buteo
jamaicensis), prairie falcon (Falco mexicanus), common raven (Corvus
corax), and rattlesnake (Crotalus sp.) (Boarman 1993, p. 2; Gustafson
1993, p. 88; Harris, pers. comm., as cited in Defenders of Wildlife and
Stewart 2005, p. 15).
Mortality may also be caused by extended periods of low amounts of
winter rainfall, which results in reduced availability of forage and
water and increases the species' vulnerability to malnutrition,
disease, and starvation. Gustafson (1993, p. 22) indicated that
prolonged periods of drought result in the extirpation of Mohave ground
squirrels in local areas as adult survival is reduced by poor forage
conditions.
Active Season and Dormancy
The Mohave ground squirrel lives in burrows which it digs
(Gustafson 1993, p. ix), and remains in burrows in a state of dormancy
throughout much of the year. For the Mohave ground squirrel, dormancy
is a physiological state that includes a reduced frequency of
breathing, or apnea, reduced oxygen consumption, reduced body
temperature (Bartholomew and Hudson 1960, pp. 195-197), and a reduced
heart rate (Ingles 1965, p. 177). Mohave ground squirrels may be active
from February to August (Bartholomew and Hudson 1960, p. 194), with
dormancy usually beginning in July or August; emergence dates vary with
elevation (Johnson no date, p. 1). In years when reproduction occurs,
most adults are active through June, but all have entered dormancy by
the end of July; in years with no reproduction, adults may enter
dormancy as early as the end of April. In contrast, juvenile Mohave
ground squirrels begin to forage outside their natal burrows by mid-May
and do not enter dormancy until July at the earliest and as late as the
end of August (Leitner and Leitner 1998, pp. 32, 38).
The period when dormancy begins varies annually. Dormancy does not
appear to be an adaptation to avoid low temperatures; rather it appears
to be an adaptation to seasonally restricted food and water
(Bartholomew and Hudson 1960, p. 202). The initiation of dormancy
appears to correspond to either the absence of available green
vegetation or its abundance (Aardahl and Roush 1985, pp. 20-21). For
the latter, the Mohave ground squirrel enters dormancy earlier as food
abundance allows the animal to meet energy needs to sustain it through
dormancy earlier (Harris and Leitner 2004, p. 521).
The principal source of energy for the Mohave ground squirrel
during dormancy is stored body fat, although food is stored in burrows
and may be consumed during the dormant period (Ingles 1965, p. 177;
Recht 1977, p. 85; Johnson no date, p. 1). During more severe drought
years, Mohave ground squirrels may enter dormancy with relatively low
body weight, which likely affects survivorship of Mohave ground
squirrels, especially juveniles, to the following spring (Leitner and
Leitner 1998, p. 32).
Home Range and Movements
In general, juvenile Mohave ground squirrels have larger home
ranges (at least twice as large) than adults, and adult males have
larger home ranges than females (Aardahl and Roush 1985, p. 11; Best
1995, p. 6). Mohave ground squirrels are territorial and, throughout
much of their active period, there is little overlap between home
ranges (Recht 1977, p. 20). Best (1995, p. 6) observed that home ranges
are separate until late June, with little evidence of territorial
behavior. The home ranges are not static and may shift during the
active season, and from year to year, in response to changes in food
quality and quantity (Best 1995, p. 6; Harris and Leitner 2004, p.
520). Home ranges of juveniles form a cluster around the home range of
an adult (Best 1995, p. 6), and adults exclude juveniles from those
portions of the habitat with the densest vegetation (Best 1995, p. 6).
Adult Mohave ground squirrels gain weight twice as fast as most
juveniles, likely due to differences in resource quality between adult
and juvenile home ranges (Recht 1977, p. 82).
Home range size varies with the reproductive period and rainfall
levels and food availability (Harris and Leitner 2004, p. 1). During
the mating season, the median male home range is much
[[Page 62221]]
larger than the female home range, 16.6 ac (6.73 ha) compared to 1.8 ac
(0.74 ha) (Harris and Leitner 2004, pp. 521-522). The females' home
ranges are non-overlapping and noncontiguous, and each individual
exhibits a high degree of site fidelity (Harris and Leitner 2004, p.
522). During the post-mating period, male home range size varies from
3.7 to 26.7 ac (1.5 to 10.8 ha), while female home range size varies
from 0.72 to 4.69 ac (0.29 to 1.90 ha) (Harris and Leitner 2004, pp.
517, 521). Female post-mating home range size is larger than the mating
season home range (Harris and Leitner 2004, p. 520).
An evaluation of different sequential survey results indicated that
juvenile Mohave ground squirrels moved farther than adults (Aardahl and
Roush 1985, p. 11), and long-distance movements were greater in males
than in females. Among juveniles, the greatest long-distance movements
between two sites for males (n = 15) was a mean of 4,987 ft (1,520 m)
(range 360-20,440 ft (110-6,230 m)), and for females (n = 21) 1,657 ft
(505 m) (range 344-12,670 ft (105-3,862 m)) (Harris and Leitner 2005,
p. 188).
Both adult male and female Mohave ground squirrels vocalize during
their active season, and have multiple types of calls (Delaney 2009,
pp. 15-17). The purpose of these calls is unknown but may be linked to
identifying home ranges.
Habitat Requirements
The Mohave ground squirrel occurs in a wide variety of habitats in
the western Mojave Desert (Wessman, as cited in Aardahl and Roush 1985,
p. 22). They include Mojave creosote bush scrub, Mojave mixed woody
scrub, desert saltbush scrub, blackbrush scrub, Mojave desert wash
scrub, Joshua-tree woodland, and shadescale scrub (Gustafson 1993, pp.
ix, 81; Bureau of Land Management (BLM) 1998, p. 1); Mojave creosote
bush scrub is the preferred habitat of the Mohave ground squirrel
(Aardahl and Roush 1985, pp. 22, 23). The Mohave ground squirrel has
also been found in some areas used for agriculture (Gustafson 1993, pp.
ix, 81; BLM 1998, p. 1).
Habitat features considered most suitable for the Mohave ground
squirrel include areas with relatively flat topography, often located
in large alluvial-filled valleys, containing fine-to-medium-textured
soil with little or no rocks, and with the presence of a variety of
native shrubs, including Larrea tridentata (creosote bush), Ambrosia
dumosa (white bursage), and Atriplex spp. (saltbush) (Aardahl and Roush
1985, p. 9).
Soil characteristics are important, as the Mohave ground squirrel
constructs burrows to escape temperature and humidity extremes and
predators, and to give birth (Aardahl and Roush 1985, p. 23). The
species is absent from very rocky areas and playas (i.e., a sandy,
salty, or mud-caked flat floor of a desert drainage basin that is
periodically covered with water) (Wessman 1977, pp. 7-9; Zembal and
Gall 1980, p. 348). Rainfall must be adequate as it affects the quality
and quantity of forage (Gustafson 1993, p. 57). Plant species diversity
and the availability of native annual forbs are important to population
stability and reproduction (Aardahl and Roush 1985, p. 22). The
presence of a variety of shrubs that provide a reliable food source
during drought years may be critical for a population to persist
(Charis 2005, pp. 3-75).
The Mohave ground squirrel is considered to be absent, or nearly
so, from dry lakebeds, lava flows, and steep, rocky slopes, although
juveniles may disperse through such areas (Leitner, pers. comm., as
cited in Laabs 1998, p. 3). Harris and Leitner (2005, p. 193) found
that Mohave ground squirrels travelled through habitats considered
marginal for permanent occupancy (e.g., contained rocky or gravelly
soils, and elevation changes of hundreds of feet) but did not cross a
playa barren of vegetation. Long-distance movement by juveniles through
marginal areas may be critical for connecting local populations and
recolonizing sites after local, drought-related extirpations (Harris
and Leitner 2005, p. 1).
Summary of Information Pertaining to the Five Factors
Section 4 of the Act (16 U.S.C. 1533) and implementing regulations
(50 CFR part 424) set forth procedures for adding species to, removing
species from, or reclassifying species on the Federal Lists of
Endangered and Threatened Wildlife and Plants. Under section 4(a)(1) of
the Act, a species may be determined to be endangered or threatened
based on any of the following five factors:
(A) The present or threatened destruction, modification, or
curtailment of its habitat or range;
(B) Overutilization for commercial, recreational, scientific, or
educational purposes;
(C) Disease or predation;
(D) The inadequacy of existing regulatory mechanisms; or
(E) Other natural or manmade factors affecting its continued
existence.
In making this 12-month finding, information pertaining to the
Mohave ground squirrel in relation to the five factors provided in
section 4(a)(1) of the Act is discussed below.
In making our 12-month finding on a petition to list the Mohave
ground squirrel, we considered and evaluated the best available
scientific and commercial information. To ensure that this finding is
based on the latest scientific information, we contacted species
experts; land managers within the range of the Mohave ground squirrel;
the CDFG; and others with expertise on the species, its habitat, and
threats occurring, or likely to occur, within the range of the species.
We conducted a search of the available published literature on the
Mohave ground squirrel and collected unpublished reports on the species
from resource agencies and others. Unpublished reports included
regional field studies by State and Federal agencies and conservation
groups, results of presence/absence surveys conducted prior to proposed
development, and incidental observations reported by field biologists.
In addition, we accessed information in the California Natural
Diversity Database. This information, information provided by the
public, and additional information and data in our files provided the
basis for the status review for the Mohave ground squirrel. In making
our 12-month finding, we considered and evaluated all scientific and
commercial information in our files, including information received
during the public comment period that ended June 28, 2010. The analysis
of potential threats to the Mohave ground squirrel discussed below
includes those identified in the petition and those identified in the
information sources listed above.
In considering what factors might constitute threats to a species,
we must look beyond the exposure of the species to a particular factor
to evaluate whether the species may respond to that factor in a way
that causes actual impacts to the species. If there is exposure to a
factor and the species responds negatively, the factor may be a threat
and, during the status review, we attempt to determine how significant
a threat it is. The threat is significant if it drives or contributes
to the risk of extinction of the species such that the species warrants
listing as endangered or threatened as those terms are defined in the
Act. However, the identification of factors that could impact a species
negatively may not be sufficient to compel a finding that the species
warrants listing. The information must
[[Page 62222]]
include evidence sufficient to suggest that the potential threat has
the capacity (i.e., it should be of sufficient magnitude and extent) to
affect the species' status such that it meets the definition of
endangered or threatened under the Act.
Factor A: The Present or Threatened Destruction, Modification, or
Curtailment of the Species' Habitat or Range
The following potential threats that may affect the habitat or
range of the Mohave ground squirrel are discussed in this section: (1)
Urban and rural development, (2) off-highway vehicle (OHV) recreational
use, (3) transportation infrastructure, (4) military operations, (5)
energy development, (6) livestock grazing, (7) agriculture, (8) mining,
and (9) climate change. Climate change is discussed under Factor A
because, although climate change may affect Mohave ground squirrels
directly by creating physiological stress, the primary impact of
climate change on the species is expected to be through changes to the
availability and distribution of Mohave ground squirrel habitat. In
addition, commercial filming occurs on private and Bureau of Land
Management (BLM) lands in the western Mojave Desert. The activities for
creating motion pictures, television shows, and commercials may require
travelling on unpaved roads and trails or cross-country use. However,
in our review of the best available scientific and commercial
information, we did not find information that indicates these filming
activities have occurred, are presently occurring, or are likely to
occur in the future within Mohave ground squirrel habitat, and
therefore, we have determined that they are not a threat to the
species.
Urban and Rural Development
The present and projected future growth of urban areas in the
western Mojave Desert could adversely affect the Mohave ground
squirrel. About 136,900 ac (55,426 ha), or 2.6 percent of the 5,319,000
ac (2,152,532 ha) range of the Mohave ground squirrel (see Background
section), has been lost to urban and rural development (Defenders of
Wildlife and Stewart 2005, pp. 19, 38). Loss of Mohave ground squirrel
habitat has occurred from the construction of residential homes,
commercial and industrial complexes, shopping malls, golf courses,
airports and associated commercial and industrial development, roads,
landfills, wastewater treatment facilities, prisons, flood management
structures, and other facilities.
Most urban and rural development has occurred in valleys, flats,
and gently sloping areas, which are the same types of areas most often
used by Mohave ground squirrels. The greatest losses of Mohave ground
squirrel habitat have occurred in, and adjacent to, cities including
Palmdale, Lancaster, Victorville, Adelanto, Hesperia, Apple Valley,
Barstow, and Ridgecrest, California (see Map 1). Smaller areas have
also been lost at the towns of Hinkley, Boron, North Edwards,
California City, Mojave, Rosamond, Inyokern, and Littlerock, and the
unincorporated communities of Pearblossom, Phelan, and Pinyon Hills,
California (see Map 1).
Most of this urban development has occurred in the southernmost
portion of the Mohave ground squirrel's range on private land,
generally south of SR-58 (see Map 1). More than 62 percent of the
private land within the range of the Mohave ground squirrel is south of
SR-58. The three cities with the largest developed areas within the
range of the squirrel (i.e., Lancaster, Palmdale, and Victorville)
occur in this area, as do several of the smaller towns listed above
(see Map 1). Some of this area has also been converted to agriculture
(see ``Agriculture'' section below), and there are areas that do not
contain suitable habitat for the squirrel (e.g., dry lake beds). We
estimate the portion of the range of the Mohave ground squirrel south
of SR-58 to be 1,690,797 ac (684,244 ha), or about 31.8 percent of the
range of the Mohave ground squirrel (see Background section for our
range analysis). Urbanization in this area is mainly concentrated along
the southern edge of the squirrel's range, and much of the area south
of SR-58 is undeveloped.
Trapping results in the southern portion of the Mohave ground
squirrel's range have generally been negative, especially in areas that
are most heavily developed (Leitner 2008, p. 5). Mohave ground
squirrels are currently known to occur in several areas south of SR-58,
including one of the largest concentrations of squirrels on EAFB (see
below). Recent records of the Mohave ground squirrel south of SR-58 and
outside EAFB include two in the Victor Valley-Lucerne Valley area
(Jones pers. comm., as cited in Defenders of Wildlife and Stewart 2005,
p. 8), four records near Adelanto (Leitner 2008, p. 7), three records
west and south of Barstow (Leitner 2008, pp. 7-8), and two records
southwest of the town of Mojave (Leitner 2008, pp. 7-8).
The fact that trapping results south of SR-58 have generally been
negative does not necessarily mean that the Mohave ground squirrel is
absent from the area or the area does not provide habitat for the
species (Leitner 2008, p. 9). Negative trapping results can occur for
various reasons, including trap location, time of trapping, and food
availability (Brooks and Matchett 2002, p. 172; Leitner 2008, p. 9)
(see ``Range and Distribution'' section and Factor D, ``State Laws and
Regulations,'' for further discussion of the survey protocol).
As discussed in the Background section, trapping surveys south of
SR-58 have most often been conducted in areas where the squirrel has
already been extirpated due to extensive urbanization, such as the
Palmdale-Lancaster area in the southwestern portion of the range
(Leitner 2008, p. 3). More importantly, large areas south of SR-58 have
either never been surveyed or have been surveyed only 1-2 times
(Leitner 2008, pp. 5, 9, 25). In addition, the trapping protocol that
was used may not be the most effective method to determine the presence
or absence of Mohave ground squirrels. Some scientists have identified
potential problems with the protocol that raise questions about the
accuracy of the current survey technique (Brooks and Matchett 2002, p.
172) (see Factor D, ``State Laws and Regulations,'' for further
discussion of the survey protocol).
Federal lands comprise 28.5 percent of the area south of SR-58 (9.3
percent of the total range of the Mohave ground squirrel). One of the
more important concentrations of Mohave ground squirrels south of SR-58
is on EAFB. The 307,435 ac (124,468 ha) EAFB encompasses about 18
percent of the area south of SR-58 (5.8 percent of the range of the
Mohave ground squirrel) and contains one of the eight important
population areas for the Mohave ground squirrel (Leitner 2008, p. 10;
se Map 2 and Background section). EAFB is used primarily for testing
and evaluating aircraft, and the impacts to Mohave ground squirrel
habitat from urban and rural development are primarily confined to the
small cantonment areas (see ``Military Operations'' section below for
details).
In addition to the Federal lands on EAFB, there are more than
175,000 ac (70,820 ha) of Federal land managed by the BLM south of SR-
58, all of which is not subject to the direct impacts of urbanization.
These BLM lands include the southern part of the Fremont-Kramer Desert
Wildlife Management Area (DWMA), which is managed for Mohave ground
squirrel habitat. Urban and rural development will not occur on these
lands (however, see ``Off-Highway
[[Page 62223]]
Vehicle Recreational Use,'' ``Military Operations,'' and ``Energy
Development'' sections below for a discussion on other activities that
may affect these areas managed by EAFB and the BLM).
We expect that further urbanization of privately owned lands south
of SR-58 will occur in the future. The population of the western Mojave
Desert is projected to grow from 795,000 (in 2000) to more than 1.5
million people by 2035 (BLM et al. 2005, p. 244). Most incorporated
cities and communities in the western Mojave Desert have general or
community plans that describe their growth and development for the next
20 years or more. We estimate that about 475,000 ac (192,226 ha), or
about 8.9 percent of the entire range of the Mohave ground squirrel, is
incorporated. The majority (about 70 percent) of the incorporated land
south of SR-58 occurs within the cities of Palmdale, Lancaster,
Victorville, Apple Valley, Hesperia, Adelanto, and Barstow. Although
these areas are already extensively urbanized, not all of the
incorporated lands south of SR-58 are developed, and future growth is
expected to occur in these areas. Under a worst-case scenario, all
areas within the incorporated boundaries could be developed in the
future.
We did not find any information on major proposed urban
developments or new communities being planned in the unincorporated and
rural lands south of SR-58, although the existing unincorporated
communities will likely continue to grow. However, we expect that
future development will most likely occur in areas that are already
incorporated because of proximity to existing infrastructure. Although
we cannot predict with any certainty what areas will be developed or
when they may be developed in the next 20-30 years, even if all
incorporated lands south of SR-58 were developed, more than 475,000 ac
(161,875 ha) would likely remain under Federal ownership south of SR-
58. Much of this land is in the Fremont-Kramer DWMA, which the BLM
designated for management of Mohave ground squirrel habitat, and
includes the important population area for the Mohave ground squirrel
at EAFB (Leitner 2008, p. 10) (see Map 2). Except for possibly minor
additions to the cantonment areas of EAFB, the Federal land south of
SR-58 is not subject to urban and rural development.
About 3,648,830 ac (1,476,635 ha) or 68.6 percent of the range of
the Mohave ground squirrel is north of SR-58. This area comprises the
central and northern portions of the range of the Mohave ground
squirrel. Most of this land has not experienced urban development;
rather, urbanization is limited and concentrated mainly around
Ridgecrest and California City. About 144,000 ac (58,275 ha), or 3.9
percent of the Mohave ground squirrel's range north of SR-58, is
incorporated, almost all of which (90 percent) is within California
City (BLM et al. 2005, chapter 3, p. 2). California City was
incorporated in 1965, and although it is the third largest city in
California in area, the population has grown to only about 14,120 in
the 46 years since it was incorporated. Additionally, most of the
incorporated area remains undeveloped. Given the slow growth rate of
California City, we believe that much of the land within its
incorporated boundaries will likely remain undeveloped.
Federal lands managed by the BLM and Department of Defense (DOD)
make up about 80 percent (2,109,326 ac (853,617 ha)) of the range of
the Mohave ground squirrel north of SR-58 (39.7 percent of the entire
range). The BLM manages 438,364 ac (177, 400 ha), while the DOD manages
1,670,962 ac (676,217 ha). Most of the 1,110,443-ac (449,382-ha) China
Lake Naval Air Weapons Station (NAWS) and the 33,359-ac (13,500-ha)
Goldstone Deep Space Communications Complex (Goldstone Complex),
managed by the National Aeronautical and Space Administration (NASA),
experience little habitat disturbance. Seven of the eight Mohave ground
squirrel important population areas are located north of SR-58, occur
mostly or entirely on Federal land (see Map 2), and are not subject to
urban development on Federal land. We do not expect any urbanization to
occur on BLM land. Because of their missions, we anticipate minimal
future urban development on the military bases; any development will
likely be limited to the cantonment areas (see ``Military Operations''
section).
In summary, we recognize that some Mohave ground squirrel habitat
has been lost to development within the range of the squirrel.
Currently, about 2.6 percent of the range of the Mohave ground squirrel
has been lost to development, and we expect that more of the range will
be lost in the future, most likely adjacent to existing urban areas. A
worst-case scenario would be that all incorporated land (about 8.9
percent (475,000 ac (192,226 ha)) within the range of the squirrel is
developed. Although unlikely because of the expected slow growth of
California City, even if this were to occur, 62 percent (3,300,000 ac
(1,335,468 ha)) of the squirrel's range is federally owned, very little
of which is subject to urban development. We estimate that about 57
percent of the Federal lands (EAFB, NAWS, Goldstone Complex, DWMAs, and
Mohave Ground Squirrel Conservation Areas (MGSCA)) are managed, at
least in part, for Mohave ground squirrel habitat (see Map 2, Table 1,
and Factor D, ``Federal Laws and Regulations''). The eight important
population areas for the Mohave ground squirrel occur mostly or
entirely within Federal lands managed in part for the Mohave ground
squirrel, and are therefore not threatened with urban development. In
addition, Leitner (2008, p. 9) has stated that additional populations
of the Mohave ground squirrel may well exist because much of the range
of the squirrel has never been surveyed or has only been surveyed 1-2
times, which may not be sufficient to determine the presence of the
squirrel (Leitner 2008, p. 25). We conclude, based on this assessment,
that urban and rural development does not currently pose a threat to
the Mohave ground squirrel in relation to the present or threatened
destruction, modification, or curtailment of its habitat or range, nor
do we anticipate it posing a threat in the future.
Table 1--Federal Lands Managed for the Mohave Ground Squirrel or Its Habitat, and the Percent of the Species'
Range \1\
----------------------------------------------------------------------------------------------------------------
Percent of Mohave ground squirrel range
-----------------------------------------------------
State/private Total area
Management areas for the Mohave ground squirrel Federal ownership \2\ within
ownership within management area
management area boundary
----------------------------------------------------------------------------------------------------------------
Mohave Ground Squirrel Conservation Area \3\.............. 16.7 7.9 24.6
Department of Defense--Limited Use/Protected.............. 27.0 0 27.0
[[Page 62224]]
Bureau of Land Management ACECs \4\ (Fremont-Kramer Desert 13.6 8.5 22.1
Wildlife Management Area, Superior-Cronese Desert
Wildlife Management Area, Desert Tortoise Research
Natural Area) \3\........................................
-----------------------------------------------------
Total................................................. 57.3 16.4 73.7
----------------------------------------------------------------------------------------------------------------
\1\ Species' range is 5,319,000 ac (2,152,532 ha) as calculated by the Service.
\2\ State/private ownership is not specifically managed for the Mohave ground squirrel.
\3\ Land ownership within designated boundary includes Federal, State, and privately-owned lands.
\4\ Area of Critical Environmental Concern.
Off-Highway Vehicle Recreational Use
Off-highway vehicle (OHV) use is any use that includes driving a
motorized vehicle off a paved road, including driving cross country and
on existing dirt roads. OHV use has the potential to adversely affect
the Mohave ground squirrel by crushing individuals (see Factor E,
``Direct Mortality'') and their burrows (Bury et al. 1977, p. 16),
damaging or destroying native vegetation, and compacting soils. Burrows
are essential to the survival of the Mohave ground squirrel, as they
provide protection from predation and the temperature extremes of the
desert, are likely used to store food, and provide a safe location for
reproduction and rearing young. Impacts to vegetation increase the
exposure of the Mohave ground squirrel to predators, decrease available
shade for thermoregulation, and increase soil temperature extremes,
which adversely affect plant germination, growth (Boarman 2002, p. 47),
and food availability. Compacted soils reduce the infiltration rate of
rain, which means there is less water available for plants and seed
germination (Boarman 2002, p. 46), reduce the root growth of
established plants, and make it harder for seedlings to survive (Lovich
and Bainbridge 1999, p. 316). With soil compaction, soil erosion from
wind and water increases, nitrogen fixation is reduced, less organic
material is available for plant growth, and seedling establishment is
reduced (Lovich and Bainbridge 1999, pp. 315-316; Boarman 2002, pp. 45-
46).
OHVs also transport nonnative annual seeds and plant parts from
other locations. Their roads, trails, and tracks act as dispersal
corridors for invasive annual plant species (Lovich and Bainbridge
1999, p. 313). These nonnative species suppress the growth of native
annual forbs (Brooks 2000, p. 105), which are a source of food and
water for the Mohave ground squirrel. Many native annual plants have a
higher percentage of water and protein than nonnative plants (Oftedal
et al. 2002, p. 344); however, we have no information on the Mohave
ground squirrel's nutritional needs and their use of nonnative plants.
Other potential impacts of OHV use include: Noise, which can cause
hearing loss in rodents (Lovich and Bainbridge 1999, p. 316) and may
interfere with the Mohave ground squirrel's ability to detect predators
and establish and maintain territories (Bury et al. 1977, p. 16);
littering and dumping of garbage (BLM 2003, p. 31), which can attract
Mohave ground squirrel predators (see Factor C, ``Predation''); and
increased fire sources (BLM 2003, p. 32), such as campfires and
cigarettes, which can result in fires that destroy Mohave ground
squirrel habitat.
In the western Mojave Desert, the BLM manages its lands for OHV
recreation. The BLM has designated four open areas (i.e., OHV
management areas) within the range of the Mohave ground squirrel as
open to all OHV use, including cross-country use (BLM et al. 2005,
chapter 3, pp. 242-243). The four OHV management areas within the range
of the Mohave ground squirrel are: (1) Dove Springs (3,840 ac (1,554
ha)); (2) El Mirage (25,600 acres (10,360 ha)); (3) Jawbone Canyon
(3,827 ac (9,642 ha)); and (4) Spangler Hills (62,080 acres (25,123
ha)) (BLM et al. 2005, chapter 3, pp. 243, 244; Service GIS data) (see
Map 2). These four areas comprise 95,347 ac (38,586 ha) (BLM 2003, p.
31), or 1.8 percent of the range of the Mohave ground squirrel. Outside
of these four areas, the BLM restricts OHV use to specific existing
roads and trails, and cross-country use is prohibited (BLM et al. 2005,
chapter 3, pp. 264-273). We are not aware of any plans on the part of
the BLM to designate new OHV management areas in the future.
The impacts from OHV use to the Mohave ground squirrel and its
habitat vary depending on the type of OHV activity, the designated land
use, and the level of enforcement. The impacts to the Mohave ground
squirrel and its habitat are greatest in open areas and high-OHV-use
areas (e.g., staging areas for OHV events, camping areas), and less in
areas where activities are confined to existing roads and trails.
Cross-country OHV use is restricted to the four management areas;
however, the occurrence of off-route OHV use tends to extend or spill
over into areas immediately adjacent to the management areas. Although
the impacts to Mohave ground squirrels likely diminish with distance
from the management areas, the BLM estimates that these ``spill-over''
zones, some of which are on private land, encompass an additional
150,239 ac (60,800 ha) (BLM et al. 2005, chapter 3, pp. 131, 132), or
2.8 percent of the range of the Mohave ground squirrel. This area,
combined with the four designated OHV management areas, constitutes
about 4.6 percent of the range of the Mohave ground squirrel.
The BLM has documented other areas not associated with the
designated management areas where OHV use of designated routes is more
frequent. The BLM estimates that these high-use areas include about
107,520 ac (43,512 ha), or 2 percent of the range of the Mohave ground
squirrel (BLM et al. 2005, chapter 3, p. 133). When combined with the
management areas and spill-over zones, about 6.6 percent of the
squirrel's range is intensively used for OHV recreation. One of the
more extensive high-use areas is the Rand Mountains area. To reduce OHV
impacts in part of the Rand Mountains area, the BLM expanded the
Western Rand Mountain
[[Page 62225]]
Area of Critical Environmental Concern (ACEC) from 17,877 ac (7,235 ha)
to 32,050 ac (12,970 ha), and closed the ACEC to OHV use except for 129
mi (208 km) of designated open routes, a 90-percent reduction in miles
of open routes (BLM et al. 2005, chapter 3, p. 8). This resulted in a
reduction of more than 14,000 acres (5,666 ha) of the high-use area in
the Rand Mountains.
Although we are not aware of any estimates, the intensive and
widespread OHV activity that occurs within the management and high-use
areas has likely resulted in extensive loss and degradation of
potential habitat for the squirrel. However, the status of the Mohave
ground squirrel within these areas is not well known. Mohave ground
squirrels have been trapped in the Dove Springs OHV Area, but not the
Spangler Hills OHV Area (Leitner 2010, in litt.). Leitner suggests that
the negative trapping results at the Spangler Hills OHV Area may be
from an inadequate trapping effort in this large area. Thus, we cannot
confirm that the Mohave ground squirrel occurs or does not occur at the
Spangler Hills OHV Area. We are not aware of any information on the
status of the Mohave ground squirrel in the other two management areas
or the high-use areas.
In addition to the management areas and high-use areas, there are
numerous single unpaved roads and trails within the range of the Mohave
ground squirrel that are used by OHVs, including utility corridors. The
potential direct and indirect impacts of roads are described above;
however, road density and OHV use of these roads are much lower than in
management areas. This lower use likely means potential impacts to the
Mohave ground squirrel are less than in management and high-use areas.
We were unable to find information on the total number of miles of
unpaved roads within the range of the Mohave ground squirrel. Based on
a 2001-2002 inventory, the BLM estimated that 5,054 linear mi (8,134
km) of roads (including paved roads, unpaved roads, and trails) occur
on BLM land in the western Mojave Desert. However, subsequent to that
inventory, the BLM permanently closed 2,260 mi (3,637 km), or 45
percent of the roads and trails (BLM 2003, pp. 4-9). Most closures
occurred in the DWMAs in Mohave ground squirrel habitat (BLM 2003, p.
396). DWMAs are ACECs where the BLM can limit or exclude surface
disturbance, including use of roads and trails (see Factor D). In
addition, the West Mojave (WEMO) Plan commits the BLM to an aggressive
program of closed route rehabilitation (BLM et al. 2005, chapter 4, p.
7). The WEMO Plan is the BLM's resource management plan for the western
Mojave Desert and amends the California Desert Conservation Area (CDCA)
Plan. It also implements the Rand Mountains Fremont Valley Management
Plan that reduces the number of open routes in the Rand Mountains by 90
percent (BLM et al. 2005, chapter 3, p. 8).
The BLM has implemented minimization measures to ensure that the
different types of OHV uses occur within the appropriate designated
management areas, roads, and trails, and thereby avoid the loss of
additional Mohave ground squirrel habitat. These measures also allow
for the eventual restoration of the habitat in areas where the roads
and trails have been closed to OHV use (although restoration time from
these impacts is believed to take several decades (Bury et al. 1977, p.
16; Lovich and Bainbridge 1999, p. 316)). These measures include
signing closed routes, obscuring closed routes with vertical mulching,
increasing public education, installing fencing and barriers, and
increasing law enforcement (BLM et al. 2005, chapter 2, pp. 156-157,
163). In 2011, BLM is signing open routes, implementing a monitoring
plan to determine compliance with route closures and whether any new
illegal routes are being created, and implementing additional
enforcement capability for the route network in the WEMO Plan area
(U.S. District Court 2011, pp. 13-15). By 2014, the BLM will be
preparing a revised OHV route network that complies with the Federal
Land Policy and Management Act's (FLPMA) requirement to minimize damage
to public resources and harassment and disruption of wildlife and
habitat (U.S. District Court 2011, pp. 2, 13). These measures should
reduce the impacts from OHV use on BLM land near management areas and
on designated roads and trails in the range of the Mohave ground
squirrel. However, the BLM's management actions for OHV use only apply
to lands that they manage; they do not apply to State or private lands.
Part or all of 14 designated Wilderness areas (BLM et al. 2005,
chapter 3, p. 9) are in the range of the Mohave ground squirrel. Under
the Wilderness Act of 1964, roads, new structures, commercial
activities, and use of motorized vehicles or equipment are prohibited
within designated wilderness areas (BLM et al. 2005, chapter 3, p. 9).
The acreage of wilderness area within the range of the Mohave ground
squirrel and therefore closed to vehicle access and other forms of
surface disturbance is about 253,000 ac (102,386 ha), or 4.6 percent of
the range of the Mohave ground squirrel. Although portions of the
wilderness areas include steep slopes and rocky substrates that would
not provide suitable habitat for the Mohave ground squirrel, most of
the wilderness areas are within the elevational range of the Mohave
ground squirrel (BLM et al. 2005, chapter 3, p. 138) and provide
connectivity among squirrel habitat.
DOD lands are closed to public access, and only persons with
business on the military installations may enter. Because of the
research, development, testing, and evaluation missions of EAFB and
NAWS (see ``Military Operations'' below), vehicle access is restricted
almost entirely to existing roads in those areas (EAFB 2008a, p. 102).
However, EAFB has designated a 10,387 ac (4,203 ha) OHV recreation area
on the base for use by base personnel (EAFB 2008a, p. 104), and Fort
Irwin has an 82 ac (33 ha) OHV recreation area (Department of the Army
2003, p. 1). Although these activities may impact the Mohave ground
squirrel and its habitat, the two areas comprise only 0.2 percent of
the squirrel's range.
There are no State Vehicular Recreation Areas (SVRAs) in the range
of the Mohave ground squirrel. SVRAs are operated and managed by the
Off-Highway Motor Vehicle Recreation Division of California State Parks
and provide trails, tracks, and other OHV recreational opportunities;
interpretive and educational activities and publications promoting safe
and responsible OHV recreation; public safety, including law
enforcement and first aid; and resource management designed to sustain
OHV opportunities and protect and enhance wildlife habitat, erosion
control, revegetation, etc. (California State Parks 2011, unpublished
information).
OHV recreation also occurs on private lands. Unauthorized OHV use
on private lands includes illegal trespass, off-trail riding, illegal
operation of non-street legal vehicles, and vandalism (Ciani 2011, p.
1). The Kern County Sheriff's Department is proposing to reduce
unauthorized OHV use on private lands by expanding and enhancing
current safety and enforcement efforts (Ciani 2011, p. 1). However,
there is no information quantifying the degree or extent of the areas
impacted by this unauthorized use, either in Kern County or anywhere
else in the range of the Mohave ground squirrel. Additionally, although
some authorized OHV activity may occur on private lands, we are unaware
of any information on the degree or extent of
[[Page 62226]]
impacts for authorized OHV activity on private lands.
OHV recreational use is likely to continue to increase in the
future. The State's population is projected to grow from 34 million in
2000 to 46 million by 2020 (BLM et al. 2005, chapter 3, p. 244). The
demand for OHV recreational opportunities is increasing, along with
California's growing population (BLM et al. 2005, p. 244). However, the
BLM has reduced the number of roads and trails available for OHV use
and has not indicated that it has plans to designate additional OHV
management or high-use areas in the range of the Mohave ground
squirrel, and the expected increase in OHV use will mainly be limited
to existing management or high-use areas.
In summary, OHV use is a popular recreational activity within
portions of the range of the Mohave ground squirrel. Potential impacts
of OHV use vary from none in wilderness areas, to substantial in
management or high-use areas, depending on the type and intensity of
OHV activity, the designated land use, and the level of enforcement.
About 6.6 percent of the range of the Mohave ground squirrel, including
BLM, DOD, and private lands, is classified as management areas,
spillover zones, or high-use areas. Although Mohave ground squirrels
have been reported in one of the four management areas, we have no
information that indicates that the impacts from OHV use in these areas
constitute a barrier to their movement. We presume the management areas
are extensively degraded and provide little value to supporting
populations of Mohave ground squirrels now or in the future; however,
these areas occur in less than 7 percent of the range of the Mohave
ground squirrel. Additionally, we have no information indicating that
additional management areas will be designated for OHV use in the
future.
In addition, the BLM has:
(1) No plans to designate additional high-use areas or roads and
trails for the next few decades,
(2) Closed 45 percent of the roads and trails in the DWMAs and 90
percent in the western Rand Mountains, and
(3) Implemented actions to restore habitat in these areas (BLM et
al. 2005 chapter 2, p. 167) and monitor compliance (such as increasing
enforcement and minimizing damage to public resources and harassment/
disruption of wildlife and habitat).
Areas of lesser use, such as existing unpaved roads and trails, can
result in the loss of habitat, and vehicle activity can crush Mohave
ground squirrels and their burrows; however, the significance of such
losses is undocumented for the Mohave ground squirrel. Although miles
of roads and trails exist, the habitat loss is essentially a narrow,
linear band, the impacts of which are minor compared to that of a
management or high-use area. Unpaved roads and trails do not result in
the total fragmentation of habitat as they are not barriers to Mohave
ground squirrel movement (Leitner 2010, in litt.).
OHV use of unpaved roads and trails also occurs on private land,
and most of this use is probably not authorized by the land owner.
However, we found no information on the extent of this type of OHV use
on private lands. At least one county in the range of the Mohave ground
squirrel has identified unauthorized OHV activities on private land as
a natural resource and public safety problem and is seeking ways to
reduce these activities through enforcement (Kern County Sheriff 2011,
unpublished information).
Using the best available information, we have determined that OHV
use is not a significant threat to the Mohave ground squirrel. We found
no information that the transport and expansion of nonnative vegetation
or potential impacts of noise and other indirect impacts are adversely
affecting the Mohave ground squirrel. The impact of OHV use to the
habitat of the squirrel mainly occurs in management, spill-over, and
high-use areas, which comprise less than 7 percent of the range of the
Mohave ground squirrel. Recreational OHV use is of minimal concern on
DOD land due to restrictions, and because only 0.2 percent of the
species' range overlaps with DOD recreational use areas. The BLM has
closed a substantial number of roads and trails in the squirrel's range
and is implementing measures to monitor and enforce these closures and
to restore habitat in the closed areas. The BLM has no plans to
establish additional areas for OHV use in the range of the Mohave
ground squirrel. Therefore, we find that OHV recreational use on BLM
land is not a significant threat to the Mohave ground squirrel.
Although we do not have an exact estimate, less than 2 percent of the
high-use area is on private land, and one county is pursuing
enforcement options to address this unauthorized OHV use and its
impacts on natural resources. In the future, we expect that OHV use
will likely increase but will be limited to existing management areas
and designated roads and trails. Therefore, based on our evaluation of
the best available scientific and commercial data, we conclude that OHV
recreational use does not currently pose a significant threat to the
Mohave ground squirrel in relation to the destruction, modification, or
curtailment of habitat or range, nor do we anticipate OHV recreational
use posing a threat in the future.
Transportation Infrastructure
Transportation infrastructure is a network of paved highways and
roads. Although we were unable to find studies on the effects of
transportation infrastructure on the Mohave ground squirrel, research
on other animals has found that the presence of roads in an area may
have a positive, negative, or no effect on animal abundance (Fahrig and
Rytwinski 2009, p. 21).
Potential positive effects of roads include greater availability of
forage plants adjacent to the roadway caused by precipitation runoff
from the roadway and fewer predators near roadways because of the
negative effects of roadways on larger mammals (Garland and Bradley
1984, p. 47; Fahrig and Rytwinski 2009, p. 21). Potential negative
impacts from construction and operation may include mortality (see
Factor E, ``Direct Mortality''), barriers to movement and fragmentation
(see Factor E, ``Fragmentation''), and habitat loss and degradation
(Gustafson 1993, pp. 23, 26; BLM 2003, p. 30; Leitner, pers. comm., as
cited in Defenders of Wildlife and Stewart 2005, p. 22).
Mohave ground squirrels may be crushed by vehicles, and the
presence of trash and other animals that are run over by vehicles
(``road kill'') may attract common ravens and other predators to the
road and nearby areas, thereby increasing the likelihood that Mohave
ground squirrels adjacent to these sites would be vulnerable to
predation (see Factor C, ``Predation''). Some studies showed that roads
produce an ecological ``road-effect zone,'' a zone over which
significant ecological effects extend outward from a road (Forman and
Deblinger 2000, p. 37). Besides road kill and loss of habitat, indirect
effects of roads in the road-effect zone may include traffic noise,
which many species avoid, and barriers to movements within a
population, with potential demographic and genetic consequences (see
Factor E, ``Fragmentation'').
Roads alter habitat upslope and downslope by causing hydrologic and
erosion effects (Foreman and Alexander 1998, p. 217), and promote the
invasion of nonnative annual plant species (Brooks 2007, p. 154). Thus,
the road-effect zone may interrupt horizontal ecological flows (e.g.,
animal movements, hydrology), alter landscape spatial patterns (i.e.,
the number, size, and arrangement of ecological pattern
[[Page 62227]]
and ecological function and process), and change species distribution
and abundance (Forman and Alexander 1998, p. 1). The interruption of
hydrologic flows may have both positive and negative impacts on the
habitat of the Mohave ground squirrel. The interruption may provide
more water to upslope habitat, thereby increasing the amount and
availability of forage. Conversely, the interruption may impede or
prevent surface flow from reaching downslope areas, thereby decreasing
the amount and availability of forage.
One major highway is planned within the range of the Mohave ground
squirrel, the High Desert Transportation Corridor. This 63-mi (101.4-
km) long east-west corridor would connect SR-14 in Palmdale with US-395
(Adelanto) and I-15 (Victorville), and would terminate on the southeast
side of Apple Valley at SR-18 (see Map 1) (San Bernardino County 2011,
unpublished information). The corridor would contain a highway with
all, or portions, composed of freeway/expressway/tollway, and it may
contain a high-speed rail line (Caltrans 2010a, p. 1). We estimate this
project would result in the loss of 7,634 ac (3,089 ha), or 0.14
percent of the range of the Mohave ground squirrel.
The new highway would be located in the southern portion of the
range of the Mohave ground squirrel, and south of the important
population area on EAFB. The highway is planned to include areas
currently developed for urban and rural use and agriculture, and thus,
the loss of Mohave ground squirrel habitat would likely be less than
the footprint of the proposed corridor. The project proponent may be
required to mitigate for the loss of Mohave ground squirrel habitat as
part of the permitting process under CESA (Jones 2011, in litt.) (see
Factor D, ``State Laws and Regulations'') and the WEMO Plan (see Factor
D, Bureau of Land Management).
Although the new highway will likely have some effect on the
habitat of the Mohave ground squirrel beyond what will be removed
during road construction, we are not aware of any study on the extent
of a potential road-effect zone or whether such a zone will have a
positive or negative impact on Mohave ground squirrel populations, or
how any impacts might change with variables, such as road width,
traffic rates, and location. The extent of the road-effect zone varies,
depending on the species being affected, location, habitat, road width,
traffic density, and other factors. For example, the road-effect zone
along one road in Massachusetts that passes through an area with many
swamps and ponds varied from greater than 328 ft (100 m) to greater
than 3,280 ft (1,000 m), and averaged 1,968 ft (600 m) (Forman and
Deblinger 2000, p. 1). However, working in the high desert of
southwestern Utah, which is similar to the environment in the west
Mojave Desert, Bissonette and Rosa (2009, p. 27) found no clear road-
effect zone for small mammals.
Although they did not conduct their study in desert areas, Adams
and Geis (1983, p. 1) found instances where population abundance of
some small mammal species was greater near roads because of their use
of the adjacent habitat created or enhanced by the roadway (e.g., water
collection, increased vegetation). In a creosote bush community in
southern Nevada, Garland and Bradley (1984, p. 47) found the effects of
roads on small mammals may differ in deserts when compared with mesic
habitats. Roadsides receive runoff from pavement, which supports lush
vegetation compared to adjacent habitat. They also found that round-
tailed ground squirrels, a close relative of the Mohave ground
squirrel, were more common near roadways (Garland and Bradley 1984, p.
54). In a review of the literature on the effects of roads on wildlife,
Fahrig and Rytwinski (2009, p. 3) found that small mammals generally
showed either a slightly positive effect from roads or no effect.
With so little known about the effects of roads on the Mohave
ground squirrel and so many variations in the road-effect zone reported
in the scientific literature, we employ a worst-case approach to our
assessment of the impact of the new highway, in which we assume that
there will be a road-effect zone associated with the new highway and
that the impacts would be so severe as to eliminate all Mohave ground
squirrel habitat within the zone. If such a zone were twice or even
three times the width of the proposed highway, then at most the zone
would result in the loss of an additional 22,902 ac (9,268 ha) of
habitat, or an additional 0.43 percent of the range of the squirrel.
In total, construction of the proposed highway could result in the
loss of less than 0.6 percent of the range of the Mohave ground
squirrel, which includes potential impacts associated with a road-
effect zone. However, the actual loss of habitat will likely be less
because some areas have already been developed and mitigation will
likely be required for the loss of habitat under the WEMO Plan and CESA
(see Factor D, Bureau of Land Management and ``State Laws and
Regulations''). Within the DWMA, the mitigation ratio is 5:1 (see
``Energy Development'' section below).
In addition to the proposed highway, two existing highways within
the range of the squirrel are planned to be modified. Areas of US-395
may be realigned and portions of SR-58 and US-395 would be widened
within the range of the Mohave ground squirrel (Caltrans District 8
website, 2010b, unpublished information). For US-395, the proposed
widening and realignment projects extend from the southern terminus at
I-15 north to Kramer Junction (see Map 1). The US-395 projects occur
within the southern portion of the range of the Mohave ground squirrel,
well outside any of the important population areas for the squirrel.
Some of the areas where the road will be widened have already been
developed (e.g., Adelanto, Victorville, Kramer Junction, etc.) and
would therefore not result in any additional loss of habitat. However,
a portion is located in the Fremont-Kramer DWMA, which is managed for
the Mohave ground squirrel (see Map 2). We estimate the proposed
highway widening would directly impact an additional 1,600 ac (647 ha),
or 0.03 percent of the range of the Mohave ground squirrel including
the areas that have already been developed. If a road-effect zone
exists for the Mohave ground squirrel, under a worst-case scenario, up
to an additional 4,800 ac (1,942 ha) of habitat could be lost, or an
additional 0.09 percent of the range of the squirrel.
For SR-58, the proposed widening projects extend from near Boron
east to 7.5 mi (12.1 km) east of Kramer Junction (see Map 1). The
project would occur in the southern portion of the range of the Mohave
ground squirrel, well outside any important squirrel population area.
Most of the proposed highway widening is located in the Fremont-Kramer
DWMA (see Map 2); however, in the Kramer Junction area, impacts to the
Mohave ground squirrel have already occurred from existing urban and
rural development. The proposed highway widening is estimated to
directly impact an additional 273 ac (110 ha), or less than 0.01
percent of the range of the Mohave ground squirrel, which includes the
areas that have already been developed. Again, under a worst-case
scenario, up to an additional 819 ac (331 ha) could be lost within the
road-effect zone.
In total, road widening would result in the loss of about 7,492 ac
(3,032 ha), or about 0.14 percent of the range of the Mohave ground
squirrel, which includes potential impacts associated with a road-
effect zone. However, the actual loss of habitat will likely be less
because some areas have already been developed and mitigation will
likely be
[[Page 62228]]
required for the loss of habitat under the WEMO Plan and CESA (see
Factor D, Bureau of Land Management and ``State Laws and
Regulations''); within the DWMA, the mitigation ratio is 5:1 (see
``Energy Development'' section below).
In summary, there are a few major highways and numerous roads
within the range of the Mohave ground squirrel. There are plans to
build a new east-west highway across the southern portion of the range
of the Mohave ground squirrel and widen two existing highways, none of
which will affect any of the important squirrel population areas.
Combined, these projects would result in the direct loss of about 9,507
ac (3,738 ha) of habitat, or about 0.18 percent of the range of the
squirrel. The actual amount would be less because some areas have
already been developed and no additional habitat would be lost, and
mitigation for loss of habitat would be required.
We acknowledge that roads may affect habitat beyond that lost
during construction. This road-effect zone can have varying degrees of
both positive and negative impacts on a species and its habitat, and
the zone can extend various distances from the road depending on
factors, such as the species being affected, location, habitat, road
width, and traffic density. For squirrels and other small mammals, the
road-effect zone tends to be neutral to slightly positive (Fahrig and
Rytwinski 2009, p. 13). Although we do not have any information that
such a zone exists for the Mohave ground squirrel or whether the
impacts within the zone would be positive or negative, based on a
worst-case scenario, an additional 28,521 ac (11,542 ha) of habitat or
about 0.54 percent of the range of the squirrel could be lost.
Therefore, based on a review of the best available scientific and
commercial data, we find that transportation infrastructure projects
likely to occur in the future could affect at most 0.74 percent of the
range of the Mohave ground squirrel, and therefore do not pose a
significant threat to the Mohave ground squirrel in relation to the
destruction, modification, or curtailment of habitat or range. Note
that other impacts that may be associated with roads, including
mortality and habitat fragmentation, are discussed under Factor E.
Military Operations
The DOD manages about one-third of the range of the Mohave ground
squirrel. Within the species' range, there are three major military
bases--Fort Irwin and the National Training Center (NTC), EAFB, and
NAWS.
Fort Irwin has three major management units; the National Training
Center (NTC), the Goldstone Deep Space Communications Complex, and the
Leach Lake Bombing Range. Fort Irwin's primary mission is training
ground forces for combat, including the use of tanks, other tracked
vehicles, and wheeled vehicles. Impacts from the training of ground
forces and associated use of wheeled and tracked vehicles would be
similar to impacts in OHV management areas (see ``Off-Highway Vehicle
Recreational Use'' section above). In addition, Fort Irwin has a small
cantonment area, which contains offices, housing, shops, restaurants,
utilities, and other facilities. The impacts to the Mohave ground
squirrel from the cantonment area would be similar to those described
above under ``Urban and Rural Development,'' but on a very small scale.
The Army has a proposal for both solar (14,000 ac (5,666 ha)) and wind
(49 ac (20 ha)) (Department of the Army 2009, p. 33) energy projects
within the boundaries of Fort Irwin (which also potentially includes
the Goldstone Complex).
The NTC is about 642,558 ac (260,035 ha), with approximately
435,978 ac (176,435 ha) within the range of the Mohave ground squirrel.
Located on the eastern edge of the range of the Mohave ground squirrel,
we estimate that 8.2 percent of the range of the species is within the
NTC boundary, which includes a recent expansion of Fort Irwin's
southwestern boundary of 75,300 ac (29,745 ha) into an area that is
within the range of the Mohave ground squirrel (see Factor D,
Department of Defense, for additional discussion on the expansion
area). Ground forces training is usually located on the flats and lower
slopes of the NTC, which are the preferred habitat of the Mohave ground
squirrel.
Prior to 1977, the Mohave ground squirrel was not known to occur on
Fort Irwin. From 1977 to the early 1990s, Fort Irwin conducted surveys
and found Mohave ground squirrels 40 mi (64 km) farther east than
previously documented occurrences (Wessman 1977, pp. 11, 12). Krzysik
(1994, p. 29) documented the impacts of ground forces training on the
habitat of the Mohave ground squirrel, which included extensive losses
of shrub cover, soil layers, and cryptobiotic soil crusts. Cryptobiotic
soil crusts are collections of symbiotic bacteria, algae, fungi, and
lichen that live on or slightly below the soil's surface and create a
semipermeable soil surface or crust. They reduce soil erosion, promote
and control water infiltration, regulate soil temperatures, catch and
convert atmospheric nitrogen, accumulate organic matter, and facilitate
native seedling establishment and growth (Boarman 2002, pp. 46 and 47),
and thus aid in the maintenance of high-quality forage and habitat for
the squirrel.
In the future, the 75,300 ac (29,745 ha) expansion area, some of
which is likely Mohave ground squirrel habitat, will be used for ground
forces training; impacts to the expansion area are expected to be the
same as areas currently used for ground forces training. However, the
entire area within the NTC is not used for ground forces training, as
some of the terrain is not suitable for training and some areas are set
aside as buffer zones to shield the training activities from civilian
uses on lands adjacent to the base's boundary. Human access to the NTC
is restricted, which precludes the use of the land for other forms of
surface disturbance (e.g., OHV recreational use, urban and rural
development, mining). Thus, while some areas are intensively used for
ground forces training, others are not and remain undisturbed.
Therefore, the estimated 8.2 percent of the range of the Mohave ground
squirrel that is within the NTC is an overestimate of the portion of
the species' range impacted by military training activities. In
addition, Fort Irwin and the NTC have implemented mitigation measures
for the Mohave ground squirrel to offset the impacts from the expansion
area (see Factor D, Department of Defense). The location of the NTC
does not appear to have an adverse effect on the movement of the Mohave
ground squirrel between the Coolgardie Mesa and the EAFB important
population areas (Bell 2006, pp. 43, 72) (see Map 2 and Significant
Portion of the Range Analysis).
The 33,359-ac (13,500-ha) Goldstone Deep Space Communications
Complex, which is operated by the National Aeronautics and Space
Administration (NASA) for tracking and communication for space
missions, is off limits to Army training activities, although a tank
trail constructed in 1985 bisects most of the Complex. Little or no OHV
use occurs within the Goldstone Complex, because there is no public
access; personal staff vehicles are confined to paved and dirt
maintenance roads, and military vehicles are restricted to the tank
trail. Therefore, the Mohave ground squirrels within the Goldstone
Complex are essentially protected from military training activities.
This is 0.6 percent of the range of the Mohave ground squirrel.
The 91,182 ac (36,900 ha) Leach Lake Bombing Range is managed by
the Air Force for live-bomb practice, and is off
[[Page 62229]]
limits for ground use because of the high risk of unexploded ordnance.
This area is 1.7 percent of the range of the Mohave ground squirrel;
however, only a small portion of it is used for bombing practice. The
remainder is managed as a buffer from human development in case a bomb
misses its intended target. Although there are likely patches of Mohave
ground squirrel habitat in the Bombing Range, their size, spatial
arrangement, and degree of habitat quality are unknown because there is
no ground access.
The 307,435 ac (124,468 ha) EAFB (see Map 1) is primarily used to
test and evaluate aircraft. Additional activities include conducting
and supporting tests of aerospace vehicles, evaluating flight and
recovery of research vehicles, participating in developmental test and
evaluation programs for the DOD and other government agencies, and
operating the Air Force Test Pilot School (EAFB 2008b, pp. iii, 19).
Because the emphasis at EAFB is training and testing in the air, the
impacts to Mohave ground squirrel habitat are minimal and localized.
Large areas of the base remain undeveloped and accommodate testing
activities and buffers for these activities. These undisturbed and
``off-limits'' areas allow EAFB to conserve natural resources and
minimize impacts to Mohave ground squirrel habitat.
Between 1993 and 2007, about 652 ac (264 ha) (about 0.2 percent of
the base) of permanent land disturbance (e.g., urban development within
the cantonment area) occurred at EAFB. EAFB recently announced plans to
construct more than 3,000 ac (1,214 ha) of solar panels in the
northwestern portion of the base to be energy self-sufficient; however,
there is no timeframe for this project. Although this project would
result in the loss of more Mohave ground squirrel habitat than has
occurred in the past at EAFB (EAFB 2008b, p. iv), it is less than 0.06
percent of the range of the Mohave ground squirrel and has been sited
to avoid: (1) The EAFB important population area; (2) areas with
recorded occurrences of Mohave ground squirrels on EAFB; and (3) areas
with likely connectivity to the south, east, and north where other
important populations of Mohave ground squirrel are present (see Map
2). OHV use is strictly confined to designated areas on the base (see
``Off-Highway Vehicle Recreational Use'' section), while other
activities that may affect Mohave ground squirrel habitat (e.g.,
livestock grazing and agriculture) are not allowed (EAFB 2008a, p. 73).
The southeast portion of the base is designated critical habitat for
the federally threatened desert tortoise, and the east boundary abuts
the Fremont-Kramer DWMA, providing connectivity to this and other areas
managed for the Mohave ground squirrel (see Factor D, Bureau of Land
Management, and Factor E, ``Fragmentation''). The Air Force has an
active program on EAFB to minimize ground disturbing activities in
desert tortoise habitat, which also benefits the Mohave ground squirrel
(EAFB 2008a, p. 74).
The Air Force has conducted Mohave ground squirrel presence/absence
surveys on EAFB since 1988, concentrating on 60 study plots distributed
throughout the base that were established to monitor long-term trends
of habitat quality and species diversity (EAFB 2008a, p. 74). Annual
trapping studies have occurred since the mid-1990s based on funding
availability (EAFB 2008a, p. 73). Mohave ground squirrels have been
trapped in all years when trapping was conducted; these results
indicate that the Mohave ground squirrel is relatively widespread on
the base except for the northwest portion. Most observations have
occurred in the east and south portions of EAFB (EAFB 2008a, p. 75).
Although densities are not available with the methodology used on EAFB,
one of the Mohave ground squirrel important population areas was
designated here because the area meets the three criteria for a
``core'' area (Leitner 2008, p. 12) (see Map 2).
The 1,110,443 ac (440,695 ha) NAWS is located in the northern
portion of the range of the Mohave ground squirrel (NAWS 2002, p. 6).
The primary function of NAWS is to research, develop, test, and
evaluate weapons systems for Navy, Air Force, Army, Joint Service,
commercial, and foreign military weapons systems. NAWS also develops
and tests airborne electronic warfare systems and performs aircraft
weapons integration (NAWS 2002, p. 1). The Mohave ground squirrel has
been studied for several years at the Coso Range in the northwest area
of NAWS (see ``Abundance and Trend'' section) and has been documented
at other locations throughout the base.
Impacts to the Mohave ground squirrel and its habitat on NAWS are
similar to those described for EAFB in both type and magnitude. Similar
to EAFB, large areas of NAWS remain undeveloped to accommodate aerial
testing activities and to serve as buffers for testing activities. For
example, NAWS tests unmanned aerial vehicles for which they need large
areas of open space to fly these vehicles and test their control
capabilities and buffers to ensure the safety of civilians outside the
base. These large undisturbed and ``off-limits'' areas allow NAWS to
conserve natural resources, including Mohave ground squirrel habitat,
on much of the base.
Cattle grazing under BLM grazing leases no longer occurs on the
base (BLM et al. 2005, chapter 4, p. 98). Feral burros and wild horses
occur on NAWS. Impacts from burros and horses include loss of annual
and woody perennial vegetation used by Mohave ground squirrels for
forage, loss of cover from predators and thermal shade, and soil
compaction from trailing (NAWS 2002, p. B-97) (see ``Grazing'' section
below). However, NAWS and the BLM have an extensive burro removal
program that has substantially reduced the impact of burros (BLM et al.
2005, chapter 2, p. 81).
In summary, Mohave ground squirrel habitat has been lost to
military operations primarily from ground forces training. The largest
area of loss is in the NTC, including the expansion area, with about
8.2 percent of the range of the Mohave ground squirrel within the NTC
boundary. However, the NTC is on the eastern edge of the range of the
Mohave ground squirrel (see Factor E, ``Fragmentation''), and not all
of the area within the NTC is impacted by ground forces training. Other
locations on DOD land, such as the Goldstone Complex and much of EAFB
and NAWS (more than 1,745,000 ac (706,180 ha)), are undeveloped and
receive little-to-no surface impacts from military operations. Because
of military security and the need for large areas of open space to test
aircraft and weapon systems and buffer areas around the test areas,
these areas become de facto conservation areas for Mohave ground
squirrel habitat.
We found no information that the DOD is proposing to change its
mission in the future and no information on proposals that would impact
additional lands within military boundaries. The DOD manages about one
third of the range of the Mohave ground squirrel. Although about 9
percent of the range of the squirrel is used for training and testing
to meet the military's mission, we estimate that 27 percent of the
range is managed under limited use or de facto habitat conservation for
the Mohave ground squirrel (see Table 1). Therefore, after reviewing
the best available scientific and commercial information, we conclude
that military operations do not currently pose a significant threat to
the Mohave ground squirrel in relation to the destruction,
modification, or curtailment of habitat or range of the species, nor do
we anticipate military operations posing a threat in the future.
[[Page 62230]]
Energy Development
Energy development includes two components, the power plant where
energy production or generation occurs, and the transmission line that
transports the energy to users. In the western Mojave Desert, power
plants currently generate energy using both non-renewable sources
(e.g., natural gas, etc.) and renewable sources (e.g., solar, wind, and
geothermal) with several proposals to generate additional energy using
renewable sources.
Power Generation
A total of 22 non-renewable and renewable energy power plants have
been constructed within or near the range of the Mohave ground
squirrel, including solar, wind, and geothermal facilities. These
facilities are located in or near cities and communities in the range
of the Mohave ground squirrel, including Little Lake, Tehachapi,
Mojave, Cantil, Argus, Trona, Boron, Hinkley, Hesperia, Victorville,
Oro Grande, Barstow, Daggett, and Newberry Springs (California Energy
Commission (CEC) 2011 Web site). These non-renewable and renewable
power plants produce energy by using water, geothermal, natural gas,
biomass, wind, solar thermal, and coal, and they have ancillary
facilities that require ongoing maintenance (such as pipelines,
transmission lines, and roads). Impacts from the construction and
operation of these existing facilities to the Mohave ground squirrel
are similar to those described below for new renewable energy projects.
In addition, several applications have been submitted to Federal,
State, and local agencies for the construction and operation of new
renewable energy projects (e.g., solar, wind, and geothermal) and
associated transmission lines, and for the expansion of existing
renewable energy projects in the range of the Mohave ground squirrel.
Various Federal and State directives foster the increase in
proposed renewable energy projects. The Energy Policy Act of 2005
requires the Department of the Interior to approve at least 10,000
megawatts (MW) of renewable energy on public lands by 2015. The
American Recovery and Reinvestment Act of 2009 provides monetary
incentives for utility-level renewable energy development that occurs
through December 2011. Executive Order 13514 declares the reduction of
greenhouse gases as a priority for Federal agencies, and Executive
Order 13212 requires Federal agencies to expedite review of energy
project applications. In addition, the Governor of California's
Executive Order S-14-08 requires California electric utilities to
obtain 33 percent of their power from renewable energy by 2020. These
laws and directives mean that renewable energy projects will likely be
located in the Mojave Desert in the future and possibly in the range of
the Mohave ground squirrel.
The Department of the Interior has and continues to receive
applications for utility-scale renewable energy projects on public
lands, primarily in the western United States. As of November 2010
(Miller 2010, in litt.), the BLM had received 23 applications for solar
and wind renewable energy projects in the CDCA, of which part or all of
each project would be located in the range of the Mohave ground
squirrel. These applications that are entirely or partly within the
squirrel's range encompass an estimated 204,200 ac (82,637 ha) of BLM
land. However, this is only a rough approximation, because at this
point in the application process we cannot determine with any accuracy
what areas fall inside or outside the range of the squirrel. Some
proposed projects are located on both BLM and private land, but the
amount on private land is not available at this time, and the location,
size, and status of many of these proposed energy projects changes
frequently. In addition, it is not likely that all of these proposed
projects will be permitted (see discussion below under Solar Projects).
In addition to those applications on BLM-managed lands, several
applications for solar and wind energy and transmission projects have
been submitted to other agencies that manage lands in the Mojave Desert
or that are privately owned. These include the DOD, Department of
Energy, CEC, California Public Utilities Commission, and County
planning agencies. At least a portion of many of these projects may
fall within the range of the Mohave ground squirrel.
In response to the Federal and State initiatives to encourage
renewable energy development and the several applications for permits
for renewable energy projects, the Renewable Energy Action Team (REAT)
was formed. Its members include the CEC, CDFG, BLM, Service, California
Public Utilities Commission, California Independent System Operators,
National Park Service, U.S. Environmental Protection Agency, and DOD.
The REAT is developing the Desert Renewable Energy Conservation Plan
(DRECP), which was mandated by California Executive Order S-14-08. This
plan is a joint State Natural Communities Conservation Plan (NCCP) and
Federal planning effort that will identify and provide measures
necessary to conserve and manage natural biological diversity within
the plan area while allowing compatible and appropriate economic
development, growth, and other human uses (California Fish and Game
Code section 2805(g)). This includes mitigation measures that will
offset impacts to sensitive species that are addressed in the DRECP,
including the Mohave ground squirrel.
Solar Projects
Solar energy projects require a large, clear area for placing and
maintaining photovoltaic panels or mirrors to produce energy and
ancillary structures, including distribution lines to transport the
generated energy to a high-voltage transmission line and provide power
to the administration and operation facilities at the site; pipelines
to supply water for administration and operation facilities and for the
production of energy (e.g., washing mirrors and panels, generating
steam to produce energy); and roads to access the project site,
distribution line route, and pipeline route(s). Some of these ancillary
structures are tens of miles long. In addition, some projects are
obligated to provide energy on cloudy days. Therefore, a backup energy
system may be constructed within the project site that uses non-
renewable energy sources, such as natural gas or propane, to produce
energy, which may require the construction of a pipeline to deliver the
hydrocarbon fuel to the project site.
Solar energy projects are likely the most destructive renewable
energy projects to Mohave ground squirrel habitat. Based on the past
construction and operation of both solar thermal and photovoltaic solar
energy projects in the Mojave Desert, the footprint of the project site
is usually a large area, most of which is cleared and maintained free
of vegetation, and the right-of-way for the transmission line and
pipeline(s) includes a maintained access road for operation and
maintenance. Solar energy projects are usually located on level or
slightly sloping ground, which is characteristic Mohave ground squirrel
habitat.
Adverse effects to the Mohave ground squirrel from construction and
operation of solar plants include crushing animals and their burrows;
loss of habitat for foraging, cover, and reproduction; increased levels
of vehicle traffic that potentially result in the increased mortality
of squirrels and increased predation; introduction of nonnative plants,
especially along pipelines, transmission lines, and access roads; and
altering habitat upslope and
[[Page 62231]]
downslope, causing hydrologic and erosion effects.
There are two existing solar thermal power plants in the range of
the Mohave ground squirrel, one near Kramer Junction and the second
near Harper Dry Lake. These two facilities, both of which are located
on private land, use solar trough or mirror technology, with backup
natural gas as an energy source to produce power at night and on cloudy
days. They cover an estimated 3,600 ac (1,457 ha), or 0.07 percent of
the range of the Mohave ground squirrel, plus additional area for
transmission lines, pipelines, and access roads. We are unaware of any
information documenting impacts of these facilities on the Mohave
ground squirrel population.
It is difficult to quantify the impacts of proposed solar energy
projects on the habitat of the Mohave ground squirrel because of the
uncertainty about their potential number, size, location, and
jurisdiction. The DOD has proposed the development of 14,000 ac (5,666
ha) for solar energy production on Fort Irwin and 3,000 ac (1,214 ha)
on EAFB. Although the average size of a solar project proposed on BLM
land is about 7,000 ac (2,832 ha), the combined size of the three
applications BLM has received that fall within the range of the Mohave
ground squirrel was originally 9,686 ac (3,920 ha) (Miller 2010 in
litt.). However, one of the three, the 3,883 ac (1,571 ha) Solar
Millennium project, was recently cancelled after 2 years of
environmental planning. It should be noted, however, that the
cancellation of this project does not preclude another project
proponent from submitting an application for solar development at the
same site. The sizes of the two remaining projects are substantially
different (5,325 ac (2,155 ha) versus 478 ac (193 ha)), which adds to
the uncertainty about potential impacts on Mohave ground squirrel
habitat. Ultimately, solar energy development on BLM land is likely to
be limited within the range of the Mohave ground squirrel. Currently,
none of the proposed solar energy projects are located in any of the
eight important population areas for the Mohave ground squirrel.
The BLM is developing programmatic-level guidance for the
development of solar energy projects and recently released a draft
programmatic Environmental Impact Statement (EIS) for solar energy (BLM
and DOE 2010). This draft EIS proposes four solar energy zones (SEZs)
on 677,400 ac (27,414 ha) in the California desert. These SEZs are
areas where the BLM would either make processing utility-scale solar
energy project applications located in SEZs a priority or restrict
solar energy project development to SEZs. None of the four proposed
SEZs is in the range of the Mohave ground squirrel, and the EIS
includes language and a map showing that BLM lands that are ACECs,
DWMAs, or Mohave ground squirrel habitat are excluded from solar
development. However, within the range of the Mohave ground squirrel,
the map identifies scattered tracts of BLM land near the edge of EAFB
and Victorville that have been identified as available for solar energy
development (BLM and DOE 2010, p. 2). We note that this is a draft
document, and the final document may be similar or different from the
current EIS. Based on the currently available information, none of the
proposed solar energy projects, the SEZs, or the scattered tracts of
BLM land are within any of the important population areas for the
Mohave ground squirrel.
Under the current WEMO Plan, which may extend to 2035, solar
development within the range of the Mohave ground squirrel will also be
restricted because the BLM has a maximum cumulative limit of 1 percent
new surface disturbance of any kind for the MGSCA. One large solar
project within the MGSCA would meet or exceed this 1-percent cap on any
kind of surface disturbance. Although the 1-percent cap also applies to
DWMAs, solar energy projects on BLM land in DWMAs are not likely to
occur because of their designation as ACECs (see Factor D, Bureau of
Land Management). The WEMO Plan also requires a mitigation ratio of 5:1
for lands within the DWMAs and the MGSCA for habitat lost from ground
disturbance (BLM et al. 2005, chapter 2, p. 204). The mitigation
generally involves acquisition of non-Federal land to add to the DWMAs
and MGSCA, but mitigation measures other than habitat acquisition may
be implemented to meet the 5:1 mitigation ratio. Outside of these
areas, the mitigation ratio is 1:1 (BLM et al. 2005, chapter 2, p. 204,
LaPre 2010). Once the DRECP is completed, the WEMO Plan would likely be
amended to adopt this plan. The current delineation for the DWMAs and
MGSCA are not likely to change with implementation of the DRECP.
BLM does not have jurisdiction over the permitting, development,
and operation of solar energy projects on private land within the range
of the Mohave ground squirrel and, therefore, does not have information
on the number, size, and location of these projects. A project on
private land may require approval from a County agency only, or from
the County and the CEC. The applications received by these agencies are
not always available to the public because of potential competition
between energy developers, and as with BLM land, the number, size, and
location of proposed solar energy projects changes frequently. However,
we are aware of 21 proposed projects on private land within the range
of the Mohave ground squirrel, which combined total 16,772 ac (6,787
ha), or about 0.3 percent of the range of the Mohave ground squirrel.
Many of these projects are proposed for areas that were previously
cleared and used for agriculture. None of these projects are located in
any of the important population areas for the Mohave ground squirrel.
In summary, the impacts from construction and operation of a solar
project in the range of the Mohave ground squirrel are similar to those
described in the ``Urban and Rural Development'' section and are
primarily loss of habitat. Two solar energy projects occur in the range
of the Mohave ground squirrel, which combined are less than 0.1 percent
of the range of the Mohave ground squirrel. The solar projects proposed
on DOD land could comprise about 0.3 percent of the range of the
squirrel. Three projects have been proposed on BLM land within the
range of the squirrel, one of which was recently cancelled. The
remaining two proposed projects make up about 0.1 percent of the range
of the squirrel. Given the limitations for future development in the
MGSCA and DWMAs, the BLM's current proposed position to either limit
utility-scale solar energy development to SEZs or make projects located
in SEZs a priority for processing over other projects, we expect that
few solar projects will be approved and constructed on BLM land within
the range of the Mohave ground squirrel within the foreseeable future.
We are aware of 21 proposed solar projects on private land, which
combined are about 0.3 percent of the range of the Mohave ground
squirrel. However, the locations for many of these projects primarily
occur on lands previously cleared for agriculture. The combined total
of existing and proposed solar projects make up no more than 0.81
percent of the range of the Mohave ground squirrel. It is unlikely that
all of the proposed projects will be built, and none of them are
located in any of the important population areas for the Mohave ground
squirrel. Therefore, based on the best available scientific and
commercial information, we
[[Page 62232]]
conclude that solar energy development is not currently a significant
threat to the Mohave ground squirrel in relation to the present or
threatened destruction, modification, or curtailment of its habitat or
range, nor do we anticipate it posing a threat in the future.
Wind Projects
At wind energy project sites, wind turbine towers are scattered
among hundreds or thousands of acres. The entire project site is not
cleared of vegetation, rather an area at the base of each tower and the
roads that provide access to the towers are cleared. Thus, the project
area is crisscrossed with cleared areas, which are used during
operation and maintenance. In addition to the roads, ancillary
facilities include meteorological towers, a substation and an
electrical collection system of buried electrical cables conveying
electricity from the wind turbines to a substation, an operation and
maintenance building, an electrical transmission line and associated
tower structures to transmit the generated power to an existing high-
voltage transmission line, and a ``switching station'' that connects
the electrical components associated from the wind turbines to the
high-voltage transmission line. Additionally, water and sewer lines are
needed for an operations and maintenance building.
Adverse effects to the Mohave ground squirrel from construction and
operation of wind energy projects include crushing animals and their
burrows; loss of habitat for foraging, cover, and reproduction;
increased levels of vehicle traffic that potentially result in the
increased mortality of squirrels and increased predation; introduction
of nonnative plants, especially along pipelines, transmission lines,
and roads; and alteration of habitat upslope and downslope causing
hydrologic and erosion effects. Although wind energy projects are
usually similar in size or larger than solar energy projects, averaging
about 8,725 ac (3,530 ha), they do not result in the elimination of all
habitat within their perimeter as solar energy projects do. Habitat
remains between the turbine pads and access roads. In addition, unlike
solar projects, wind energy projects are frequently located on
ridgelines, slopes, or in passes and would not likely be in areas with
habitat characteristics preferred by Mohave ground squirrels. However,
we have no information on how Mohave ground squirrel populations have
been affected by currently operating wind energy projects or how they
would be affected by the construction and operation of proposed wind
energy projects.
Small patches of wind resources that are considered economically
feasible to develop occur within the range of the Mohave ground
squirrel (LM 2005, Appendix B, pp. 31-32), and some wind development is
likely to occur. However, most of the large, commercially important
wind fields in the Mojave Desert are to the west and south of the
squirrel's range. So far, wind energy projects have been constructed on
non-Federal land along the western edge of the Mohave ground squirrel's
range in Kern County. Existing projects encompass about 4,900 ac (1,983
ha) or about 0.01 percent of the range of the Mohave ground squirrel
(Waln 2011, p. 1). Wind turbines in this area have been placed mainly
on hilltops and ridgelines, which are not generally suitable habitat
for the Mohave ground squirrel.
It is difficult to quantify the impacts of proposed wind energy
projects on the habitat of the Mohave ground squirrel. Applications
have been submitted and withdrawn, and the size and location of the
projects have changed after submission. It should be noted, however,
that even if a project is cancelled, it does not prevent another
project proponent from submitting an application for wind development
at the same site. Recently the demand for energy sources from wind has
been dampened by a reduction in the price of newly-found sources of
natural gas and concerns over the future of renewable energy subsidies
from Congress (Ball 2011, p. 2). As with solar energy projects, there
is no single entity that is responsible for overseeing the development
and operation of all wind energy projects in the Mojave Desert or
within the range of the Mohave ground squirrel.
There is uncertainty in the development of future wind energy
projects in the range of the Mohave ground squirrel. For example, only
one wind project has been proposed on DOD land, a 49 ac (20 ha) project
on Fort Irwin. In 2010, the BLM reported receiving 20 applications for
wind energy projects totaling about 194,000 ac (78,509 ha) (Miller
2010, in litt.), although not all proposals occur within the range of
the Mohave ground squirrel. The average project size is about 9,700 ac
(3,925 ha), but sizes range from 160 ac (65 ha) to 45,385 ac (18,367
ha) (Miller 2010, in litt.). In contrast, in 2011 the BLM's list of
wind energy applications (BLM 2011a, pp. 1, 3, and 4) did not include
eight projects from the 2010 list. This change from 2010 was a
reduction of about 86,000 ac (34,803 ha).
The total acreage of currently proposed wind energy projects that
potentially occur in the range of the Mohave ground squirrel is about
107,347 ac (43,442 ha), or about 2 percent of the range of the species.
In addition, the actual number of acres that fall within the range of
the Mohave ground squirrel is likely to be far less because at this
early stage in the proposal process the boundaries of each project are
very generalized, and some of the current proposals overlap and some
are partly outside the squirrel's range. In fact, requests for permits
submitted to the BLM far exceed the 72,300 ac (29,259 ha) of
economically developable wind resources that the BLM estimates occur on
the lands they manage in the entire State of California (BLM 205, pp.
2-5). Most of the currently proposed wind energy projects on BLM land
are located along the west and southeast edges of the range of the
Mohave ground squirrel, and most are located on ridgetops and
hillsides, which are not considered suitable habitat for the Mohave
ground squirrel.
The BLM's wind energy program established policies, Best Management
Practices (BMPs), and an Instructional Memorandum (IM 2009-043,
December 19, 2008) to address the administration of wind energy
development activities and identify minimum requirements for mitigation
measures. These programmatic policies and BMPs would be applicable to
all wind energy development projects on BLM lands. Site-specific and
species-specific concerns, and the development of additional mitigation
measures, would be addressed in project-level reviews, including
National Environmental Policy Act (NEPA) analyses, as required (BLM
2005, Volume 1, Chapter ES, p. 4) (see Factor D below for a discussion
of NEPA). For example, the BLM recommends establishing a policy by
which right-of-way grants will not be issued for lands where wind
energy development would be incompatible with specific resource values
(BLM 2005, Volume 1, Chapter 2, pp. 6-7), such as those found within
ACECs. Additional areas of land may be excluded from wind energy
development on the basis of findings of resource impacts that cannot be
mitigated and/or conflict with existing and planned multiple use
activities or land use plans (BLM 2005, Volume 1, Chapter 2, p. 7).
Other BLM policies include incorporating management goals and
objectives specific to habitat conservation for species of concern (BLM
2005, Volume 1, Chapter 2, p. 9), such as the Mohave ground squirrel.
[[Page 62233]]
Under the current WEMO Plan, which may extend to 2035, wind
development within the range of the Mohave ground squirrel will also be
restricted because the BLM has a maximum cumulative limit of 1 percent
new surface disturbance of any kind for the MGSCA and 1 percent for
each of the two DWMAs. One large wind project within the MGSCA would
meet or exceed this 1-percent cap on any kind of surface disturbance.
The WEMO Plan also requires a mitigation ratio of 5:1 for lands within
the DWMAs and the MGSCA for habitat lost from ground disturbance (BLM
et al. 2005, chapter 2, p. 204). The mitigation generally involves
acquisition of non-Federal land to add to the DWMAs and MGSCA, but
mitigation measures other than habitat acquisition may be implemented
to meet the 5:1 mitigation ratio. Outside of these areas, the
mitigation ratio is 1:1 (BLM et al. 2005, chapter 2, p. 204; LaPre
2010, in litt.). Although compensation is required, there is no
requirement that the lands acquired will be enhanced or excluded from
future development projects, but they are subject to the 1-percent
development cap. Once the DRECP is completed, the WEMO Plan would
likely be amended to adopt this plan. The current delineations for the
DWMAs and MGSCA are not likely to change with implementation of the
DRECP.
Although patches of economically developable wind resources occur
on private land throughout the range of the Mohave ground squirrel,
most of the proposed and approved projects are along the western edge
of the Mohave ground squirrel's range in Kern County. The Kern County
Planning and Community Development Department listed 16 wind projects
as either approved for construction or as deemed complete to begin the
approval process (Kern County Planning 2011, pp. 1-2). Thirteen of
these projects are located partly or entirely within the range of the
Mohave ground squirrel. Their area is estimated to be 47,000 ac (19,020
ha), or about 0.9 percent of the range of the Mohave ground squirrel.
In summary, existing wind energy projects occur in the range of the
Mohave ground squirrel and additional projects have been proposed and
approved. Most wind energy projects are or will be located on ridgetops
and hillsides, which are not considered suitable habitat for the Mohave
ground squirrel for feeding, breeding, or shelter. None of the existing
or proposed wind energy projects are located in any of the important
population areas for the Mohave ground squirrel.
The impacts from construction and operation of a wind energy
project in the range of the Mohave ground squirrel would likely be
similar to those described under the ``Off-Highway Vehicle Recreational
Use'' section but with low vehicle use due to restricted access, the
impacts would be reduced.
Current operational wind energy projects are on non-Federal lands
on the western edge of the range of the Mohave ground squirrel and
encompass about 0.01 percent of the species' range. Plans for wind
energy development on DOD land are limited to 49 ac (20 ha) on Fort
Irwin. On BLM land, development of wind energy projects in the MGSCA
would be limited and none is likely to occur in the DWMAs in the future
as the BLM has imposed restrictions on future development in these
areas. Although likely an overestimate, if we assume that all proposed
wind energy projects on BLM land are entirely within the range of the
Mohave ground squirrel, would be constructed, and would result in the
total loss of habitat within the project boundaries, 107,347 ac (43,442
ha), or 2 percent of the range of the Mohave ground squirrel, would be
lost. On non-Federal land, about 47,000 ac (19,020 ha), or 0.9 percent
of the range of the Mohave ground squirrel, have proposed or recently
approved wind energy projects. The combined total of existing,
proposed, and approved wind projects make up at most about 3 percent of
the range of the Mohave ground squirrel; however, this is an
overestimate as the projects would not result in a total loss of Mohave
ground squirrel habitat.
Therefore, based on the best available scientific and commercial
information, we conclude that wind energy development does not
currently pose a threat to the Mohave ground squirrel in relation to
the present or threatened destruction, modification, or curtailment of
its habitat or range, nor do we anticipate it posing a threat in the
future, because:
(1) Large areas of economically developable wind resources do not
occur within the range of the Mohave ground squirrel;
(2) The number and size of proposed or approved development on DOD
land is limited;
(3) There are limitations on the areal extent of development in the
MGSCA and DWMAs; and
(4) Typical construction and operation of wind energy projects does
not result in the total loss of habitat within the project site.
Geothermal Projects
A typical geothermal project has one or more power plants, a series
of wells scattered throughout an area, pipelines delivering water to
the wells and heated water to the power plant(s), a substation,
transmission lines to a high-voltage transmission line, administrative
offices, water and sewer lines, and ponds. Geothermal projects are not
limited to a particular type of terrain as are wind turbines; they may
or may not be located in areas with suitable habitat for Mohave ground
squirrels. However, ancillary facilities such as transmission lines,
pipelines, and access roads, would likely occur in Mohave ground
squirrel habitat.
Adverse effects to the Mohave ground squirrel from construction and
operation of geothermal energy projects include crushing animals and
their burrows; loss of habitat used for foraging, cover, and
reproduction; increased levels of vehicle traffic that potentially
result in the increased mortality of squirrels and increased predation;
introduction of nonnative plants, especially along pipelines,
transmission lines, and roads; and altering habitat upslope and
downslope causing hydrologic and erosion effects. Similar to wind
energy projects, the overall size of geothermal projects may be large,
but the entire project area is not cleared of vegetation, which leaves
patches of habitat within the project area. Habitat patches would
remain between the wells, pipelines, transmission poles/towers, and
access roads.
Unlike solar and wind energy projects, geothermal energy projects
are restricted to very specific areas where geothermal energy is
sufficient and near the surface. There are only two locations in the
range of the Mohave ground squirrel with actual and potential
geothermal resources (Known Geothermal Resource Areas (KGRA)). One, the
Coso Hot Springs KGRA, is on both NAWS (NAWS 2002, p. 47) and BLM land
in the northern portion of the range of the Mohave ground squirrel; the
second, the Randsburg KGRA, is mostly or entirely on BLM land near
Randsburg in the central portion of the range of the squirrel (BLM et
al. 2005, Appendix P-2, p. 3; California Department of Conservation
2002, p. 1). The single existing geothermal power plant, the Coso
geothermal plant, is located in the Coso Hot Springs KGRA and consists
of 106,000 ac (42,897 ha), or 2.0 percent of the range of the Mohave
ground squirrel. Completed in 1987, it has 4 power plants and more than
120 wells producing 270 MW of energy (NAWS 2002, p. 48). Within the
Coso Hot Springs KGRA, the BLM recently approved a 55 ac (22.3 ha) (BLM
2008, p. 13) project that includes
[[Page 62234]]
a groundwater extraction and pipeline delivery system for injection
into the existing geothermal project. The addition of the 9-mile-long
(14.5-km-long) pipeline and access right-of-way would expand the
existing energy output by pumping an additional 4,800 ac-feet
(5,920,713 cubic meters) of ground water per year, extending the life
of the power plants.
Although a geothermal energy project has been constructed in the
range of the Mohave ground squirrel, we have no information on how
Mohave ground squirrel populations have been affected by the currently
operating project and can therefore only speculate how the Mohave
ground squirrel would be affected by the construction and operation of
proposed geothermal energy projects. Mohave ground squirrels at the
existing project in the northwest portion of the species' range have
been studied, but the purpose of the study was to gather data on the
effects of excluding livestock grazing and provide data on the biology
of the Mohave ground squirrel (Leitner and Leitner 1998, p. i), and not
the impacts of geothermal development on the squirrel. Only one of the
important population areas for the Mohave ground squirrel, the Coso
Range--Olancha area, is near the Coso geothermal power plant. Although
the power plant is on the southern edge of this important population
area for the Mohave ground squirrel, it has not been reported as having
been affected by construction and operation of the geothermal plant.
The BLM issued a decision on the final programmatic Environmental
Impact Statement (EIS) for geothermal development in December 2008 (BLM
and USFS 2008). In its Record of Decision, the BLM determined that
issuing a geothermal lease does not cause any effect on a species, as
there is no guarantee that any development will ever take place on such
a lease (BLM 2008c pp. 1-22). If development does take place, prior to
the development the BLM would examine individual projects and phases
(exploration, development, and operation) to determine the appropriate
level of environmental analysis needed to comply with NEPA (BLM and
USFS 2008, pp. 2-23) and address the impacts to the Mohave ground
squirrel at that time. In addition, the BLM would apply stipulations on
any lease where a special status species, such as the Mohave ground
squirrel, is known or strongly suspected to occur. These stipulations
include modifications to existing exploration and development proposals
or modifications to lease terms (BLM 2008c pp. 1-23). The BLM has
developed BMPs for geothermal projects which include requiring the
operator or lessee to identify important, sensitive, or unique habitats
and biota in the project vicinity, and siting and designing the project
to avoid (if possible), minimize, or mitigate potential impacts on
these resources (BLM and USFS 2008, p. D-6), such as the Mohave ground
squirrel. During each stage from exploration to utilization, the BLM
retains the authority to approve, deny, or approve with conditions such
as protective measures (BLM 2008c, pp. 1-24). In the CDCA, geothermal
leasing is designated for all lands, with the exception of wilderness
areas (BLM 2008c, pp. 2-3; BLM 1999, p. 15). We are not aware of any
proposed geothermal projects on private lands in the range of the
Mohave ground squirrel.
On September 11, 2009, the BLM issued a notice of intent to prepare
an EIS for the exploration, development, and use of up to an additional
22,060 ac (8,927 ha), or 0.4 percent of the range of the Mohave ground
squirrel in the northern resource area (74 FR 175 46786-46787). Within
this 22,060 ac (8,927 ha) area, the BLM has received three applications
for new geothermal development on 4,460 ac (1,805 ha), or 0.08 percent
of the range of the Mohave ground squirrel. The BLM has received no
applications for geothermal energy development near Randsburg.
Once the DRECP is completed, the WEMO Plan would likely be amended
to adopt this plan. The current delineations for the DWMAs and MGSCA
are not likely to change with implementation of the DRECP.
In summary, there are limited locations for geothermal energy
projects within the range of the Mohave ground squirrel. Currently,
there is only one operating geothermal energy project in the range of
the squirrel, and its impacts on the Mohave ground squirrel and its
habitat have not been studied. Although an important population area
for the Mohave ground squirrel is nearby the existing project, the
Mohave ground squirrel has not been reported as having been affected by
construction and operation of the geothermal plant. Additional
geothermal energy projects have been proposed in the vicinity of the
existing plant, and, when added to the existing project, would impact
about 2.1 percent of the range of the Mohave ground squirrel. However,
the impacts would likely not affect the entire area, as not all of the
habitat within these geothermal energy areas is removed during
construction and operation; not all of the habitat within the project
sites is likely to be suitable for the Mohave ground squirrel; and the
BLM is required to implement best management practices to avoid (if
possible), minimize, or mitigate potential impacts to species of
concern, such as the Mohave ground squirrel. Therefore, we conclude
that the construction and operation of geothermal energy projects are
not currently a threat to the Mohave ground squirrel, nor do we
anticipate geothermal energy projects posing a threat in the future.
Utility Corridors
The development of renewable energy projects in the western Mojave
Desert will require construction of new transmission lines and the
upgrading of existing transmission lines to carry the increased
electrical energy production. Pipelines are also needed to carry water
to some solar and geothermal energy plants for daily operational needs
and natural gas or propane to some solar energy plants for energy
production on cloudy days.
Utility corridors may impact the Mohave ground squirrel and its
habitat in various ways. Construction activities result in direct
impacts by crushing Mohave ground squirrels and their burrows, and
collapsing burrows, which destroy the shelter the species needs to
escape temperature extremes and predators and to rear young.
Construction activities also unearth, injure, or kill other animals
that attract Mohave ground squirrel predators, such as the common
raven. The construction and use of unpaved roads along transmission
lines and pipelines affect Mohave ground squirrel habitat in the same
manner as roads created and used by OHVs (see ``Off-Highway Vehicle
Recreation Use'' section); OHVs would also use the utility corridors.
The physical structures (e.g., towers and pads, access roads) cause
loss of habitat and facilitate predation of the Mohave ground squirrel
by providing nesting, roosting, and perching habitat for common ravens
and birds of prey (Boarman and Heinrich 1999, pp. 23-24). Because of
ongoing operation and maintenance, the recovery or restoration of these
areas of lost habitat is limited (Lovich and Bainbridge 199, p. 313).
Because we have no reliable information on the number, size, and
location of potential renewable energy projects in the range of the
Mohave ground squirrel, we have no reliable information of the number,
size, and location of their associated utility lines. However, utility
corridors in the range of the Mohave ground squirrel already exist,
having been designated by the BLM. In the range of the Mohave ground
squirrel, these corridors generally run
[[Page 62235]]
closely parallel to major highways, including I-15, US-395, SR-58, and
SR-178 (Inyokern to Ridgecrest and Trona). Corridors that are not
associated with highways, or that are only occasionally associated with
highways, include ones along the Mojave River, another along the
southern boundary of Fort Irwin, two north-south corridors in the
western Antelope Valley, and one east-west corridor near SRs-138 and 18
(Palmdale to Victorville) (BLM 2011b, p. 1). The purpose for
designating the corridors is to provide a coordinated and consolidated
delivery system network that meets the needs of the public and
minimizes the proliferation of rights-of-way, construction, and loss of
habitat through the western Mojave Desert (BLM et al. 2005, Chapter 3,
p. 275). The BLM requires all new linear utilities exceeding certain
thresholds to be placed within these designated corridors (BLM et al.
2005, chapter 3, pp. 274-275).
It is difficult to quantify the impacts of proposed transmission
lines and pipelines (``lines'') on the habitat of the Mohave ground
squirrel. First, the number, length, and location of new lines are
dependent on the size, number, and location of new solar, wind, and
geothermal development. Applications for these have been submitted and
withdrawn, and the size and location of some of the projects may have
changed after they were submitted. The cost of constructing new lines
is a significant part of the overall cost of an energy project, and
therefore, most power suppliers locate their power generation source
close to an existing utility corridor to reduce costs. Regardless, many
miles of new lines and associated access roads will likely be
constructed in the range of the Mohave ground squirrel, a portion of
which will be outside of existing utility corridors.
Another important factor in determining the overall impact of new
lines on the Mohave ground squirrel and its habitat is that the BLM
requires mitigation for the Mohave ground squirrel from direct impacts
of projects, such as energy development, and utility construction and
maintenance. The WEMO Plan requires a mitigation ratio of 5:1 for lands
within the DWMAs and the MGSCA for habitat lost from ground disturbance
(BLM et al. 2005, chapter 2, p. 204). The mitigation generally involves
acquisition of non-Federal land to add to the DWMAs and MGSCA, but
mitigation measures other than habitat acquisition may be implemented
to meet the 5:1 mitigation ratio. Outside of these areas, the
compensation requirement is at a rate of 1:1 (BLM et al. 2005, chapter
2, p. 204, LaPre 2010, in litt.). Although compensation is required,
there is no requirement that the lands acquired will be enhanced or
excluded from future development projects, but any acquired lands are
subject to the 1-percent development cap. Thus, habitat acquisition may
result in securing blocks of habitat for the Mohave ground squirrel,
but it will also result in a net loss of total available acres of
habitat. In addition, the CDFG may require mitigation for the loss of
Mohave ground squirrel habitat as part of the permitting process under
CESA (see Factor D, ``State Laws and Regulations'').
In summary, the construction and operation of utility corridors may
impact the Mohave ground squirrel through increased animal mortality
and the loss and degradation of habitat used for feeding, breeding, and
sheltering. Utility corridors have been designated to minimize the
proliferation of rights-of-way through the western Mojave Desert and
range of the Mohave ground squirrel. Many are located along existing
highways, which confines the locations and impacts of linear structures
and minimizes new impacts to Mohave ground squirrel habitat. Where
these rights-of-way cross BLM land, any permitted surface disturbance
would be limited to a 1 percent development cap in the MGSCA and the
DWMAs and the mitigation rate would be 5:1. Outside these special
management areas, the mitigation rate would be 1:1. Thus, habitat for
the Mohave ground squirrel would likely be lost, but this loss would be
confined mainly to the utility corridors and other areas of habitat
would be acquired through mitigation that could benefit the Mohave
ground squirrel.
Summary of Energy Development
In summary, 22 non-renewable and renewable energy projects have
been constructed within the range of the Mohave ground squirrel. No new
non-renewable projects have been proposed; however, many more renewable
energy projects have been proposed. Existing solar, wind, and
geothermal projects encompass about 2.2 percent of the range of the
Mohave ground squirrel. However, at the present time, there is a great
deal of uncertainty as to the number, size, and location of future
energy development and its potential impact on the Mohave ground
squirrel. This uncertainty is caused by a number of factors, including
overlapping proposed projects, the cost of supplying renewable energy
compared to other energy sources, and whether or not the December 2011
construction deadline for funding under the American Recovery and
Reinvestment Act of 2009 will be extended.
Although we are not aware of any studies on the impact of renewable
energy development on the Mohave ground squirrel, at least some loss of
habitat will occur, with the potential amount and suitability of the
habitat lost dependent in part on the type of energy development. Solar
energy development may occur anywhere there is flat or gently sloping
land, which is where Mohave ground squirrel habitat usually occurs, and
is likely the most destructive type of renewable energy to Mohave
ground squirrel habitat because most of the area is cleared of
vegetation during construction and operation. In contrast, wind
development is limited to those areas with economically developable
wind energy and generally occurs on ridges and hilltops, while
geothermal development within the range of the Mohave ground squirrel
is limited to two areas where geothermal energy can be commercially
developed. The impact of both wind and geothermal development may also
be less than solar because much of the vegetation is not cleared during
their construction.
Future solar and wind development on Federal land, which makes up
about two-thirds of the range of the Mohave ground squirrel, is likely
to be limited for several reasons. No solar and wind projects exist on
the 37 percent of the range of the Mohave ground squirrel that is
managed by the DOD, while proposed solar and wind development on DOD
land makes up about 0.3 percent of the range of the Mohave ground
squirrel. On BLM land, which includes about one-third of the range of
the Mohave ground squirrel, existing renewable energy projects make up
about 2.1 percent of the range of the squirrel, most of which is
geothermal. However, the BLM has received applications for solar, wind,
and geothermal projects that could encompass about an additional 2.2
percent of the range of the Mohave ground squirrel. This level of
development on BLM land is likely an overestimate because the BLM has
implemented a 1-percent cap (BLM et al. 2005a, chapter 2, p. 48) on all
new development, including energy projects, in the 1,726,722 ac (698,78
ha) MGSCA and in the two DWMAs, which total 1,155,835 ac (467,752 ha)
(BLM et al. 2005, chapter 2, pp. 15, 48, 204) (see Map 2 and Factor D);
the BLM also requires extensive and potentially expensive mitigation in
these areas. This cap means the BLM would limit new development in each
of these areas, which make up most of the range of the
[[Page 62236]]
BLM land within the range of the Mohave ground squirrel, to no more
than 1 percent under the current WEMO Plan, which may extend to 2035.
However, the proposed renewable energy projects in these limited
development areas may already exceed this 1-percent cap, which means
not all of the proposed projects would be built, and no other permitted
projects of any kind with surface disturbance could occur in these
areas.
For solar development, the BLM has proposed four SEZs in its
programmatic EIS for solar energy, all of which are outside the range
of the Mohave ground squirrel and within which solar development is
more likely to occur. Wind development may be more likely to occur on
BLM land within the range of the Mohave ground squirrel than solar, but
it will be restricted because of the 1-percent cap within the MGSCA and
each of the DWMAs and the required mitigation. The mitigation ratio for
ground disturbing activities within the MGSCA is 5:1; for land
acquisition that means up to 65,440 ac (26,483 ha) of private lands
(inholdings) in the MGSCA could be purchased and become part of the
MGSCA if the entire 1 percent (13,088 ac (5,297 ha)) was developed. The
same mitigation requirement (1-percent cap on development and 5:1
mitigation ratio) applies in the DWMAs, where up to 86,335 ac (34,939
ha) could be added to the DWMAs. However, assuming the worst-case
scenario that all proposed wind and geothermal projects on BLM land are
developed within the range of the Mohave ground squirrel, then as much
as 2.2 percent of the range would be affected.
On non-Federal land, which comprises about one-third of the range
of the Mohave ground squirrel, several solar and wind energy projects
have been proposed that would impact about 1.2 percent of the range of
the Mohave ground squirrel. However, many of the projects on private
land will be constructed on land previously converted to agriculture.
Therefore, although most probably an overestimate, 5.9 percent of the
range could be lost as a result of renewable energy development. None
of the existing or proposed renewable energy projects on Federal or
private land are located within any of the important population areas
for the Mohave ground squirrel.
Renewable energy development will also require the construction of
additional utility lines, which may result in the loss of Mohave ground
squirrel habitat. These additional lines will be limited in the MGSCA
and the DWMAs, as energy development in these areas is expected to be
limited, long utility lines add substantially to the cost of a project,
and the lines are subject to the 1-percent development cap and the 5:1
mitigation ratio. New lines would be subject to a 1:1 mitigation ratio
outside the MGSCA and DWMAs.
In conclusion, existing non-renewable energy development has
occurred in or near cities and communities in the range of the Mohave
ground squirrel; however, no new non-renewable projects are proposed.
Renewable energy development has occurred in rural areas within the
range of the Mohave ground squirrel and has been mainly limited to
solar thermal development in the central portion of the range and
geothermal development in the northern portion of the range. Future
development on Federal land, which makes up about two-thirds of the
range, is likely to occur outside the MGSCA and the DWMAs. Development
on BLM land outside the MGSCA and the DWMAs will require a mitigation
ratio of 1:1. This mitigation could include the acquisition of
additional lands to be included in the DWMAs and MGSCA. Proposed energy
development on DOD land makes up 0.3 percent of the range. We are aware
of several proposed projects on private land, but many of them are in
areas where the site has been graded, so the habitat is not suitable
for the Mohave ground squirrel. Therefore, after reviewing the best
available scientific and commercial information, we conclude that
energy development does not currently pose a threat to the Mohave
ground squirrel in relation to the present or threatened destruction,
modification, or curtailment of its habitat or range, nor do we
anticipate it posing a threat in the future.
Livestock Grazing
Potential impacts from livestock grazing to Mohave ground squirrel
habitat are mainly from degradation of soils and vegetation rather than
direct loss of habitat, which is limited to construction and use of
certain livestock improvements, such as livestock troughs, stock tanks,
and corrals (Lovich and Bainbridge 1999, p. 313). Habitat degradation
due to grazing occurs to varying degrees and includes soil compaction,
destruction or degradation of cryptobiotic soil crusts, decreased water
infiltration, increased erosion, trampling of plants, and overcropping
(Lovich and Bainbridge 1999, p. 311). Grazing also collapses burrows
(Boarman 2002, p. 28). Several studies have been conducted that
document the impacts of livestock grazing, especially overgrazing, on
soils and vegetation in the Mojave Desert (Busack and Bury 1974, pp.
181-182; Berry 1978, pp. 511-515; Webb and Stielstra 1979, pp. 522-527;
Nicholson and Humphreys 1981, pp. 171-81; Brooks 1995, pp. 67-69; Avery
1998, pp. 67-68).
In the Mojave Desert, livestock grazing impacts soils in various
ways. It damages cryptobiotic soil crusts (see ``Military Operations''
section) in the open spaces between desert shrubs and causes soil
compaction. In a comparison of soil conditions following sheep grazing
in the western Mojave Desert, Webb and Stielstra (1979, pp. 522-523)
noted that surface strength (a measure of compaction) was significantly
greater in grazed as compared to ungrazed areas, particularly in the
upper 4 in (10 cm) of the soil, and that surface erosion was greater
after grazing.
Grazing has also been found to reduce the number of seeds in a soil
seed bank (Brooks 1995, p. 670), which contributes to changes in plant
communities. In the western Mojave Desert, a study comparing grazed and
ungrazed plots reported the grazed plot had reduced native forb density
(Larson et al. 1997, as cited in Boarman 2002, p. 34). Native
vegetation biomass in the Mojave Desert is higher in areas protected
from grazing, while nonnative grass biomass is greater outside
protected areas (Brooks 1995, pp. 67-68).
The impacts to soils and vegetation in active allotments vary by
location and intensity. For much of the grazing season, the areas
livestock graze are limited by distance from water. Grazing intensity
and associated impacts are generally greater near watering areas, but
decrease substantially within a short distance (Boarman 2002, p. 34),
and some areas within an allotment may not be grazed because of their
distance from water.
Although several studies have been conducted on the effects of
livestock grazing on soils and vegetation in the Mojave Desert, we
found only one study on the effects of livestock grazing on the Mohave
ground squirrel. This study focused on dietary overlap, not impacts to
soils and vegetation. Using fecal microhistological analysis, Leitner
and Leitner (1998, pp. iv, 27) reported that both Mohave ground
squirrels and livestock rely on the leaves from shrubs, particularly
one uncommon shrub, Krascheninnikovia lanata (winterfat). This reliance
by both livestock and squirrels was greater in dry years. The
researchers concluded there was dietary overlap between the Mohave
ground squirrel and cattle (Leitner and Leitner 2006, p. 38), but
provided no information on whether this overlap
[[Page 62237]]
was impacting the Mohave ground squirrel.
Cattle and sheep grazing are authorized within the range of the
Mohave ground squirrel. The majority of grazing occurs on BLM land, but
grazing also occurs on private land. The BLM has designated 21 grazing
allotments (11 sheep, 7 cattle, and 3 cattle/sheep) within the range of
the Mohave ground squirrel (BLM et al. 2005, chapter 2, pp. 125, 130;
chapter 3, pp. 213, 215-216). An allotment is an area designated for
grazing for a private rancher to use. The grazing program in the WEMO
Plan addresses BLM lands only; however, many of the BLM allotments
include both public and private lands (BLM et al. 2005, chapter 2, p.
130).
With adoption of the WEMO Plan, the BLM made several changes to
grazing management. The BLM implemented public land health standards
and guidelines for grazing management to improve ecological conditions
and ensure healthy sustainable rangelands (BLM et al. 2005, chapter 2,
p. 118). The standards in the WEMO Plan include managing soils and
native species' habitats by managing ecological processes, and include
indicators to evaluate whether populations and their habitats are
sufficiently distributed and healthy to prevent the need for listing
under the ESA (BLM et al. 2005, chapter 2, p. 121). The BLM is required
to restore, maintain, or enhance habitats of special status species,
such as the Mohave ground squirrel, to promote their conservation (BLM
et al. 2005, chapter 2, p. 124).
Under the WEMO plan, specific management changes to livestock
grazing in the range of the Mohave ground squirrel included reducing
the area authorized for grazing in the range of the Mohave ground
squirrel by 33 percent; eliminating ephemeral grazing for cattle in the
DWMAs; eliminating sheep grazing in most of the DWMAs; excluding cattle
grazing in the spring in DWMAs in years when annual plant productivity
is low; excluding cattle grazing on NAWS; and allowing permittees to
voluntarily relinquish cattle and sheep allotments (BLM et al. 2005,
chapter 2, pp. 127, 132-135). These management prescriptions will be in
effect during implementation of the current WEMO Plan, which may extend
to 2035. The area currently authorized for grazing by the BLM within
the range of the Mohave ground squirrel habitat is 1,718,686 ac
(695,530 ha) of BLM and private land (BLM et al. 2005, chapter 3, pp.
213, 215-216; Waln 2010, p. 1), or about 32.3 percent of the range of
the Mohave ground squirrel (see ``Range and Distribution'' section). In
addition, the BLM reports that although no allotments have been
voluntarily relinquished, the permittee for the 45,619 ac (38,994 ha)
Pilot Knob allotment has not grazed livestock recently and has
requested relinquishment (Fitton 2010, in litt.). This area is 0.9
percent of the range of the Mohave ground squirrel.
We do not have any information on regionwide grazing on private
lands outside of BLM allotments; therefore, the total area grazed
presented above underestimates the actual area of grazing within the
range of the Mohave ground squirrel (BLM et al. 2005, Appendix M, no
page number).
Mohave ground squirrel habitat can also be degraded by feral burros
and wild horses, which occur in the northern portion of the species'
range. Impacts to Mohave ground squirrel habitat from feral burro and
wild horses are hypothesized to be similar to those of livestock
grazing. The extent of these impacts on Mohave ground squirrel habitat
is likely influenced by wild horse and feral burro population density,
topography and soils, resident plant communities, spatial and temporal
scale, other disturbances, year to year and longer term climatic
variation, and animal behavior (Abella 2008, p. 817).
The BLM has an ongoing program on its lands to capture and move
feral burros and wild horses (BLM et al. 2005 chapter 2, p. 90), and
although these animals remain within the range of the Mohave ground
squirrel, their degree of impact they have on the habitat of the Mohave
ground squirrel has been greatly reduced. The Navy also has an ongoing
program to capture and move burros and horses from the NAWS (see
``Military Operations'' section).
In summary, although livestock grazing may result in the
degradation of soils and vegetation, it rarely results in the direct
loss of habitat, and there is no information that demonstrates
livestock grazing is negatively impacting Mohave ground squirrel
habitat. The focus of studies on livestock grazing in the Mojave Desert
has been on general impacts to soils and vegetation rather than how
those impacts are affecting the Mohave ground squirrel and its habitat.
One study found there was dietary overlap between the Mohave ground
squirrels and livestock for one forage species, but provided no
information that this was adversely affecting the Mohave ground
squirrel. Although we are not aware of any significant impacts of
grazing on Mohave ground squirrel habitat, soil and habitat degradation
associated with grazing have been further reduced with the BLM's recent
implementation of public land health standards and guidelines for
grazing. Recent BLM actions in the range of the Mohave ground squirrel
include eliminating grazing in some areas and reducing it in others,
which should improve the condition of the soils and vegetation,
particularly in the MGSCA and the DWMAs (see Map 2). Over time, these
changes are likely to provide increased foraging opportunities for the
Mohave ground squirrel and reduce the overall amount of time that
livestock spend within these areas, thus reducing impacts to soils,
vegetation, and dietary overlap. Therefore, based on the best available
scientific and commercial data, we conclude that livestock grazing does
not currently pose a threat to the Mohave ground squirrel in relation
to the present or threatened destruction, modification, or curtailment
of its habitat or range, nor do we anticipate livestock grazing posing
a threat in the future.
Agriculture
Agriculture occurs in the range of the Mohave ground squirrel.
Agricultural development results in the conversion of native desert
habitat to croplands and orchards. In addition to the direct loss of
habitat, agricultural activities expose Mohave ground squirrels and
nearby habitat to insecticides, herbicides, and rodenticides (Hoyt
1972, p. 7). Because the Mohave ground squirrel eats both plants and
insects, it could be adversely affected by the loss or reduction of
these food items from the use of insecticides and herbicides. In
addition, drift of insecticides, herbicides, or rodenticides from the
fields into adjacent habitat or bioaccumulation of these chemicals from
contaminated forage and insects could adversely affect the Mohave
ground squirrel.
We found no information that the use of pesticides is adversely
affecting the Mohave ground squirrel from direct exposure, reduction of
forage, or bioaccumulation from consuming treated vegetation or
insects. Habitat loss from agricultural activities has occurred at
several locations within the range of the Mohave ground squirrel. By
the early 1990s, more than 39,000 ac (15,700 ha), or 0.7 percent of the
range of the Mohave ground squirrel, had been lost to agriculture,
including areas in the Antelope Valley and Mojave River Basin
(Gustafson 1993, p. 24). In 1994, Krzysik (1994, p. 18) reported that
the spread of alfalfa fields throughout the species' southern range in
the Mojave River area had destroyed prime Mohave ground squirrel
habitat and fragmented populations. Krzysik (1994, p. 18) concluded
that the Mohave ground squirrel was no longer found in the
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Lucerne Valley, Apple Valley, or Victorville areas, which are in the
southern portion of the squirrel's range (see Map 1). We estimate this
area to be about 2.4 percent of the range of the Mohave ground
squirrel. However, there have been recent sightings of the Mohave
ground squirrel near Adelanto and Hesperia (Victorville/Mojave River
Valley area) and Mojave (western Antelope Valley) (Leitner 2008, pp. 6-
7) (see Map 1).
We acknowledge that past agricultural development resulted in the
destruction of Mohave ground squirrel habitat. However, the current
cost of pumping ground water to irrigate crops in the western Mojave
Desert discourages the development of new areas for agriculture (Los
Angeles County Cooperative Extension 2009, p. 1). In addition, many
areas historically used for agriculture are being converted to
residential and commercial development (Los Angeles County Cooperative
Extension 2009, p. 1). This conversion would not result in additional
loss of habitat for the Mohave ground squirrel, as the native
vegetation had previously been removed when developed for agriculture.
After reviewing the information on Web sites of local agricultural
agencies in the western Mojave Desert, we conclude that there will
likely be no increase in agricultural development in the future. Given
the best available scientific and commercial data, and the small
percent of the range of the species affected by agriculture, we
conclude that agriculture does not currently pose a threat to the
Mohave ground squirrel in relation to the present or threatened
destruction, modification, or curtailment of its habitat or range, nor
do we anticipate it posing a threat in the future.
Mining
Limited mining occurs in the range of the Mohave ground squirrel,
and includes mineral, sand, and gravel mines. Mining results in the
loss of Mohave ground squirrel habitat through removal of vegetation
used for forage and cover, and removal of soils used for burrows, which
provide protection from temperature extremes and predation, and serve
as a location to give birth. Travel off road during mining exploration,
and the construction and use of roads to access the mine site during
production, also result in the loss of habitat (Boarman 2002, p. 18).
These activities impact the Mohave ground squirrel by damaging and
removing shrub cover and compacting the soil (see ``Off-Highway Vehicle
Recreational Use'' section above for additional details). Extracting
minerals is usually done by constructing addits (a type of horizontal
shaft), shafts, and/or pits. The unused materials may include
overburden, waste ore, and tailings, which are deposited near the mine
site. A mining operation may require office space, storage facilities,
and power plants at the mine site. These activities impact Mohave
ground squirrels through a direct loss of habitat, similar to impacts
from urban development, although on a reduced scale (Boarman 2002, p.
18) (see ``Urban and Rural Development'' section).
Mining has occurred in the western Mojave Desert for more than a
century. Minerals extracted in the western Mojave Desert include gold,
borates, and aggregate materials (sand, gravel, and stone). Mine size
ranges from less than a few acres for recreational mining and
exploration, to large commercial mines covering several square miles.
However, most of the mines in the western Mojave Desert are small and
their impacts are very limited and localized.
The only extensive mining operation in the range of the Mohave
ground squirrel is the U.S. Borax borate mine located north of Boron
(see Map 1). This operation is proposing to increase its footprint by
1,500 ac (607 ha) (U.S. Borax 2008, Figure ES-2), which would allow the
mine to operate past 2050. Sand, gravel, cement, and other mineral
commodities used for construction materials are in demand as the
population in the western Mojave Desert and southern California
continues to grow. We anticipate there will be an increase in demand
for these materials in the future in the western Mojave Desert (BLM et
al. 2005, Appendix P, p. 2), despite the current slowdown in the
economy. As sand and gravel mining operations deplete their material
sources at currently approved mining sites, they will likely request
permits to expand their current operation sites (e.g., Ag Con in Oro
Grande, San Bernardino County 2003 Mining Conditional Use Permit and
Reclamation Plan). Mine expansion would result in the loss of Mohave
ground squirrel habitat, but this loss would likely be minimal in area
when compared to the range of the species (far less than 0.01 percent
of the range). Much smaller existing or proposed gold and silver mines
are in the Mojave-Rosamond and Randsburg areas, but these mines are
located on rocky buttes and do not occur in Mohave ground squirrel
habitat.
Commercial and recreational mining does not occur on DOD lands. On
public land, the BLM allows mining in all areas, unless the land has
been withdrawn from mineral entry. Lands not withdrawn but requiring an
approved plan of operation prior to commencing mining activities
include proposals to remove more than 1,000 tons of ore, to disturb
more than 5 ac (2 ha) of BLM land, or to be located on lands that are
ACECs or wilderness. Class L public lands are limited-use areas to help
protect sensitive, natural, scenic, ecological, and cultural resource
values. These public lands are also managed to provide for generally
lower-intensity, carefully controlled multiple use of resources, while
ensuring that sensitive values are not significantly diminished. Class
C public lands are wilderness areas with controlled use that is also
closed to OHV use (BLM et al. 2005, chapter 3, p. 3 and Appendix P, p.
4). Casual mining use or prospecting can occur on BLM lands in the
western Mojave Desert, as can commercial mining. However, the DWMAs are
ACECs and the MGSCA area is Class L land. The BLM would need to approve
a plan of operation prior to anyone initiating mining activities in
these areas. The plan of operation would also need to include the 5:1
mitigation ratio, and mine development would contribute to the 1-
percent development cap. Given these requirements, it is unlikely that
mining would occur on these lands in the range of the Mohave ground
squirrel in the future.
In summary, mining occurs in the range of the Mohave ground
squirrel on private and BLM lands. However, using the best available
scientific and commercial information, we find that only a small number
of known active and proposed mines occur in the range of the Mohave
ground squirrel; many of these mines are located in areas that are not
suitable habitat (i.e., rocky, mountainous areas) for the Mohave ground
squirrel; and commercial mining is absent on DOD lands (which
constitute about one third of the range of the species). Therefore, we
conclude that mining does not currently pose a threat to the Mohave
ground squirrel in relation to the present or threatened destruction,
modification, or curtailment of its habitat or range, nor do we
anticipate it posing a threat in the future.
Climate Change
Climate change may be impacting the Mohave ground squirrel. Climate
change is discussed here under Factor A because, although climate
change may affect the Mohave ground squirrel directly by creating
physiological stress, the primary impact of climate change on the
Mohave ground squirrel is expected
[[Page 62239]]
to be through changes to the availability and distribution of Mohave
ground squirrel habitat.
``Climate'' refers to an area's long-term average weather
statistics (typically for at least 20- or 30-year periods), including
the mean and variation of surface variables, such as temperature,
precipitation, and wind, whereas ``climate change'' refers to a change
in the mean and/or variability of climate properties that persists for
an extended period (typically decades or longer), whether due to
natural processes or human activity (Intergovernmental Panel on Climate
Change (IPCC) 2007a, p. 78). Although changes in climate occur
continuously over geological time, changes are now occurring at an
accelerated rate. For example, at continental, regional and ocean basin
scales, recent observed changes in long-term trends include: A
substantial increase in precipitation in eastern parts of North America
and South America, northern Europe, and northern and central Asia, and
an increase in intense tropical cyclone activity in the North Atlantic
since about 1970 (IPCC 2007a, p. 30); and an increase in annual average
temperature of more than 2 degrees Fahrenheit (F) (1.1 degrees Celsius
(C)) across the U.S. since 1960 (Global Climate Change Impacts in the
United States (GCCIUS) 2009, p. 27). Examples of observed changes in
the physical environment include: An increase in global average sea
level, and declines in mountain glaciers and average snow cover in both
the northern and southern hemispheres (IPCC 2007a, p. 30); substantial
and accelerating reductions in Arctic sea ice (e.g., Comiso et al.
2008, p. 1), and a variety of changes in ecosystem processes, the
distribution of species, and the timing of seasonal events (e.g.,
GCCIUS 2009, pp. 79-88).
The IPCC used Atmosphere-Ocean General Circulation Models and
various greenhouse gas emissions scenarios to make projections of
climate change globally and for broad regions through the 21st century
(Meehl et al. 2007, p. 753; Randall et al. 2007, pp. 596-599), and
reported these projections using a framework for characterizing
certainty (Solomon et al. 2007, pp. 22-23). Examples include: (1) It is
virtually certain there will be warmer and more frequent hot days and
nights over most of the earth's land areas; (2) it is very likely there
will be increased frequency of warm spells and heat waves over most
land areas, and the frequency of heavy precipitation events will
increase over most areas; and (3) it is likely that increases will
occur in the incidence of extreme high sea level (excludes tsunamis),
intense tropical cyclone activity, and the area affected by droughts
(IPCC 2007b, p. 8, Table SPM.2). More recent analyses using a different
global model and comparing other emissions scenarios resulted in
similar projections of global temperature change across the different
approaches (Prinn et al. 2011, pp. 527, 529).
All models (not just those involving climate change) have some
uncertainty associated with projections due to assumptions used, data
available, and features of the models; with regard to climate change
this includes factors such as assumptions related to emissions
scenarios, internal climate variability and differences among models.
Despite this, however, under all global models and emissions scenarios,
the overall projected trajectory of surface air temperature is one of
increased warming compared to current conditions (Meehl et al. 2007, p.
762; Prinn et al. 2011, p. 527). Climate models, emissions scenarios,
and associated assumptions, data, and analytical techniques will
continue to be refined, as will interpretations of projections, as more
information becomes available. For instance, some changes in conditions
are occurring more rapidly than initially projected, such as melting of
Arctic sea ice (Comiso et al. 2008, p. 1; Polyak et al. 2010, p. 1797),
and since 2000 the observed emissions of greenhouse gases, which are a
key influence on climate change, have been occurring at the middle to
higher levels of the various emissions scenarios developed in the late
1990s and used by the IPPC for making projections (e.g., Raupach et al.
2007, Figure 1, p. 10289; Manning et al. 2010, Figure 1, p. 377; Pielke
et al. 2008, entire). Also, the best scientific and commercial data
available indicate that average global surface air temperature is
increasing and several climate-related changes are occurring and will
continue for many decades even if emissions are stabilized soon (e.g.
Meehl et al. 2007, pp. 822-829; Church et al. 2010, pp. 411-412;
Gillett et al. 2011, entire).
Changes in climate can have a variety of direct and indirect
impacts on species, and can exacerbate the effects of other threats.
Rather than assessing ``climate change'' as a single threat in and of
itself, we examine the potential consequences to species and their
habitats that arise from changes in environmental conditions associated
with various aspects of climate change. For example, climate-related
changes to habitats, predator-prey relationships, disease and disease
vectors, or conditions that exceed the physiological tolerances of a
species, occurring individually or in combination, may affect the
status of a species. Vulnerability to climate change impacts is a
function of sensitivity to those changes, exposure to those changes,
and adaptive capacity (IPCC 2007, p. 89; Glick et al 2011, pp. 19-22).
As described above, in evaluating the status of a species, the Service
uses the best scientific and commercial data available, and this
includes consideration of direct and indirect effects of climate
change. As is the case with all potential threats, if a species is
currently affected or is expected to be affected by one or more
climate-related impacts, this does not necessarily mean the species is
a threatened or endangered species as defined under the Act. If a
species is listed as threatened or endangered, this knowledge regarding
its vulnerability to, and impacts from, climate-associated changes in
environmental conditions can be used to help devise appropriate
strategies for its recovery.
While projections from global climate model simulations are
informative and in some cases are the only or the best scientific
information available, various downscaling methods are being used to
provide higher resolution projections that are more relevant to the
spatial scales used to assess impacts to a given species (see Glick et
al. 2011, pp. 58-61). With regard to the area of analysis for the
Mohave ground squirrel, downscaled projections are available to some
degree. Specifically, the IPCC models predict that precipitation will
decrease, but the frequency and magnitude of extreme precipitation
events will increase. The IPCC provides a more recent report that
supports EPA's prediction of temperature increases and adds that rising
air and ocean temperature is unquestionable (IPCC 2007a, p. 4). The
Western Regional Climate Center's California Climate Tracker has
developed 11 climate-monitoring regions for California. The western
Mojave Desert is part of one region that includes most of the Mojave
Desert in California and the Owens Valley. Data collected from this
region indicate that mean, maximum, and minimum temperatures have
increased during the last 110 years (Redmond 2009, pp. 36-46).
There is still a considerable degree of uncertainty associated with
projecting future climate change, due in part to uncertainties about
future emissions of greenhouse gases and to differences among climate
models and simulations (Stainforth et al. 2005, pp. 403-406; Duffy et
al. 2006, pp. 873-874), and to the inability to predict change at a
local scale. It is difficult with currently
[[Page 62240]]
available models to make meaningful predictions of climate change for
areas such as the range of the Mohave ground squirrel (Parmesan and
Matthews 2005, p. 354). The difficulty in predicting how an animal or
plant will respond further increases the uncertainty of evaluating the
potential impacts of climate change. Responses may include changes in
distribution, population size, behavior, and physiological and physical
characteristics (Parmesan and Mathews 2005, p. 373). Several published
studies predict that temperature and precipitation trends may change in
the near future, and some describe how biotic communities may respond
to such changes (Parmesan and Mathews 2005, pp. 333-374; IPCC 2007a,
pp. 1-21; IPCC 2007b, pp. 1-22; Jetz et al. 2007, pp. 1211-1216; Kelly
and Goulden 2008, pp. 11823-11826; Loarie et al. 2008, pp. 1-10; Miller
et al. 2008, pp. 1-17). In the interior western region of the United
States, species may respond to increases in temperature by shifting
their range to cooler areas.
The Mohave ground squirrel usually occurs in the flats and alluvial
fans between rocky, mountainous areas. Based on the specific known
habitat requirements of the Mohave ground squirrel, the species could
respond to ambient temperature increases in three general ways: (1)
Constrict its range; (2) move farther north; or (3) move higher in
elevation within its current range. Moving farther north would require
travelling over rocky hills, which is difficult, but possible, in some
areas for the Mohave ground squirrel (see ``Home Range and Movements''
section). Moving to higher elevations would require the Mohave ground
squirrel to cross rocky terrain and inhabit more marginal habitats at
higher elevations with less suitable substrate for burrow construction.
The most likely response by the Mohave ground squirrel to climate
change would be to move north. However, we cannot be certain that the
Mohave ground squirrel will respond this way. Regardless of the
species' response to ambient temperature increases, ultimately the
range of the species will likely be smaller than it is currently.
Based on the information discussed above, we acknowledge that
temperatures in the western Mojave Desert where the Mohave ground
squirrel occurs have increased and are likely to continue increasing.
We also acknowledge that, if hotter and drier summers and more extreme
weather patterns in temperature and precipitation occur within its
range, the Mohave ground squirrel may be negatively affected. As
discussed in the ``Biology and Natural History'' section, the activity
period of the Mohave ground squirrel is generally spring and early
summer when they mate and forage to sustain themselves for the
remainder of the year. Increased temperatures could cause Mohave ground
squirrels to have a shorter active period. A reduced active period may
lessen the species' ability to consume and store sufficient forage to
sustain it through the dormant period, and may reduce the frequency of
reproduction. If precipitation declines, the availability of nutritious
forage would likely decline in a given year and across years. If such
reduced precipitation levels persist, the habitat may no longer be
suitable for the Mohave ground squirrel during the drought period.
Drought is a natural feature of the Mojave Desert. The State of
California has experienced cycles of drought for many years. For
example, between 1928 and 1987 the U.S. Geological Survey (USGS)
reported five severe droughts across California, including the longest
drought in the State's history during the period 1929-1934 (USGS 2004,
p. 2).
The Mohave ground squirrel has evolved several adaptations to
persist in an environment with drought. These adaptations include
suppressing reproduction during periods of low rainfall and food
availability, retreating to burrows for most of the year to escape
temperature and humidity extremes in summer and winter, reducing
physiological demands by going into a state of torpor for much of the
year, and caching food in burrows. However, prolonged drought
exacerbates the effects of drought on the species; no young may be born
for several years, the survivability of adults is reduced by poor
forage conditions, and the surviving adults eventually die due to old
age or predation (Gustafson 1993, p. 22). This situation can result in
the extirpation of the Mohave ground squirrel in local areas (Gustafson
1993, p. 22). However, based on past records of severe drought, the
Mohave ground squirrel has demonstrated that it can persist and
recolonize areas following episodes of severe drought. Therefore, we
have no information that supports the assumption that severe drought
will threaten the species in the foreseeable future.
We also have no information on which to base meaningful predictions
on how climate change may influence the duration or severity of drought
within the range of the Mohave ground squirrel, or how its status may
be affected. Increasing temperature could result in more severe and
frequent drought, especially in the Southwest (Karl et al. 2009, p.
42). However, we are not aware of any formal studies on the direct
effect of rising global temperature on drought severity or frequency
(Karl et al. 2009, p. 5). Drought severity and frequency are a function
of a complex series of factors, such as the El-Nino-Southern
Oscillation (ENSO) intensity and duration, as well as geographic
variations in sea surface temperature, which may also be affected by
increasing temperatures (Karl et al. 2009, p. 105), thereby compounding
the uncertainty associated with precipitation projections (Karl et al.
2009, p. 105).
In summary, within the range of the Mohave ground squirrel, the
potential effects of climate change, their magnitude, and projections
on how the species will react are speculative for several reasons,
including the uncertainties of climate projection models, the lack of
models for projecting climate change for relatively small geographic
areas, the complexity of interacting factors that may influence
vegetation changes, and the uncertainty regarding the effects of
climate change on the Mohave ground squirrel's foraging, breeding, and
movement/dispersal behaviors. Although climate change may have some
effect on the species, at this time we cannot make meaningful
projections on either how the climate within the range of the Mohave
ground squirrel may change, or how the species may react to climate
change. The Mohave ground squirrel has survived several periods of
drought in the 20th century, including a 5-year drought in the early
20th century, and has evolved several adaptations to persist in an
environment with drought as a natural feature of its environment,
including recolonizing areas following episodes of severe drought.
Therefore, based on a review of the best available scientific and
commercial data, we conclude that climate change does not currently
pose a threat to the Mohave ground squirrel in relation to the present
or threatened destruction, modification, or curtailment of its habitat
or range, nor do we anticipate it posing a threat in the future.
Summary of Factor A
We have assessed the best available scientific and commercial data
on the impacts of urban and rural development, OHV recreational use,
transportation infrastructure, military operations, energy development,
livestock grazing, agriculture, mining, and climate change on the range
and habitat of the Mohave ground squirrel.
Urban and rural development destroys habitat used by the Mohave
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ground squirrel for feeding, breeding, and shelter; reduces or prevents
movement of individuals among populations (see Factor E); and
introduces human behaviors that result in an increase in the number of
Mohave ground squirrel predators (see Factor C). Most habitat loss
occurs at the southern end of the species' range in the incorporated
areas of Palmdale, Lancaster, Victorville, Apple Valley, Hesperia,
Adelanto, and Barstow (see Map 1). Except for California City, which is
located in the central part of the Mohave ground squirrel's range (see
map 1), these cities make up almost all the incorporated lands within
the squirrel's range. Not all the incorporated lands within these
cities are developed; however, because of the proximity to existing
infrastructures, we expect that future growth will take place in these
incorporated areas. We cannot predict with any certainty how much or
which of these areas will be developed in the next 20-30 years.
Currently, about 2.6 percent of the range of the squirrel has been lost
to urban and rural development. The development of all incorporated
areas would result in the loss of approximately 9-10 percent of the
Mohave ground squirrel's range; this number includes the 2.6 percent of
the range already lost to development. However, this is highly unlikely
because we expect very limited development of California City (or 2.45
percent of the species' range), which is the largest incorporated area
within the range of the squirrel.
OHV recreational use occurs throughout much of the range of the
Mohave ground squirrel. However, impacts to the Mohave ground squirrel
and its habitat occur mainly in the most heavily used areas (management
areas, spill-over zones, and high-use areas). If we assume that all
habitat in the management areas, spill-over zones, and high-use areas
has been severely impacted, then about 6.6 percent of the range of the
Mohave ground squirrel has been lost to OHV use. However, we know that
the Mohave ground squirrel continues to occur on at least one of the
four management areas. Areas of lesser use (e.g., existing unpaved
roads and trails) result in the loss of habitat, and vehicle activity
can crush Mohave ground squirrels. However, the significance of such
losses is undocumented for the Mohave ground squirrel and does not
result in the total fragmentation of habitat, as unpaved roads and
trails are not barriers to Mohave ground squirrel movement (Leitner
2010, in litt.). In addition, the BLM, through implementation of the
WEMO Plan, has no plans to designate additional high-use areas or roads
and trails for the next few decades, has closed 45 percent of the roads
and trails in the DWMAs and 90 percent in the Rand Mountains ACEC (BLM
et al. 2005, chapter 2, p. 167), is restoring habitat in areas of
closed roads and trails, is increasing enforcement, and is revising its
route designation to minimize damage to public resources and harassment
and disruption of wildlife and habitat.
Several highways and roads cross the western Mojave Desert. This
network of roads potentially impacts the Mohave ground squirrel and its
habitat by direct mortality, loss of habitat from initial construction,
introduction of invasive plants, and alteration of habitat upslope and
downslope from hydrologic and erosion effects. One new highway is
proposed in the southern portion of the range of the Mohave ground
squirrel, and two highways are proposed for widening, which combined
would result in the loss of at most 0.18 percent of the range of the
squirrel. Although there is no information specific to the Mohave
ground squirrel, roads are known in some cases to affect species and
their habitat beyond the loss of habitat from construction of the road
itself. This road-effect zone can have varying degrees of both positive
and negative impacts, with the width of the zone varying with the
species affected, location, habitat, road width, and traffic density.
There is research that indicates that the effects of roads on small
mammals in the desert are neutral to slightly positive. Assuming the
worst case scenario that such a road-effect zone exists for the Mohave
ground squirrel, and its impacts to the species' habitat are severe, we
estimate that about 0.74 percent of the range could be lost.
Military operations vary in their magnitude and intensity of
impacts to Mohave ground squirrel habitat. Ground force training
activities that use live ammunition, ordnance, and tracked and wheeled
vehicles remove vegetation, compact the soil, and cause fires that
remove perennial plants. These activities, including the Fort Irwin
expansion area, occur on about 8.2 percent of the range of the Mohave
ground squirrel. Bombing and weapons testing often result in intense
disturbance in small areas while large buffer areas remain undisturbed.
Flight-testing and training have limited if any ground impacts.
Training areas for the military bases in the western Mojave Desert have
buffer areas where surface disturbance is limited, or not allowed.
However, much of the habitat on the three major bases in the western
Mojave Desert, especially EAFB and NAWS, is protected from human
impacts, such as urban and rural development, OHV recreational use,
agriculture, and grazing, because these activities are not compatible
with the military mission. Approximately 37.2 percent of the range of
the Mohave ground squirrel occurs within the boundaries of Fort Irwin,
EAFB, and NAWS. Although about 8.2 percent of the military land is
intensively used for military operations, much of the remainder of its
range within these DOD facilities is not heavily used, and large
undisturbed areas are needed to test aerial vehicles and weapons and to
act as buffer areas around target sites. To maintain the ongoing
mission of the military, these large, undisturbed areas must remain
undeveloped. Thus, while habitat for the Mohave ground squirrel is
severely impacted in some areas by military operations, there are
extensive areas where it does not experience these impacts.
Several renewable energy projects and utility lines have been
constructed or are proposed for construction in the range of the Mohave
ground squirrel. Besides the direct loss of potentially large areas of
habitat from the construction of new facilities, new and existing
energy projects can also facilitate an increased presence of predators
and promote invasive plants. Solar projects are likely to be the most
destructive to Mohave ground squirrel habitat because these projects
are situated in relatively flat or gently sloping areas that are
preferred by the squirrel and because all vegetation is removed during
construction and operation. There are two existing solar projects
within the range of the squirrel, which make up about 0.07 percent of
the range. Both of these projects are on private land; there are no
projects at the present time on BLM or DOD land within the range of the
squirrel. Unlike solar projects, wind turbines are often situated on
ridges and hilltops, which are not the squirrel's preferred habitat,
and geothermal energy only occurs in two areas within the range of the
squirrel. Also, all vegetation is not cleared during the construction
of wind and geothermal projects. Existing wind projects are on private
land on the western edge of the squirrel's range and make up about 0.1
percent of the range. There are no wind projects on BLM or DOD land at
the present time. There is one large geothermal project on Federal land
that makes up about 2 percent of the range, although much of the
habitat in this area has not been destroyed.
[[Page 62242]]
Combined, existing renewable energy projects make up about 2.2 percent
of the range of the Mohave ground squirrel.
Several renewable energy projects have been proposed on both
Federal and private land in the range of the Mohave ground squirrel.
However, at the present time, there is a great deal of uncertainty as
to the number, size, and location of future energy development and its
potential impact on the Mohave ground squirrel. This uncertainty is
caused by a number of factors, including the overlap of proposed
projects, the cost of supplying renewable energy compared to other
energy sources, and the uncertainty of whether or not the December 2011
construction deadline for funding under the American Recovery and
Reinvestment Act of 2009 will be extended. Proposals for solar and wind
projects on DOD land, which include about 27 percent of the range of
the Mohave ground squirrel, would encompass about 0.3 percent of the
range, if constructed. Proposed solar and wind projects on BLM land,
which includes about one third of the range of the squirrel, would
encompass about 2.2 percent of the range, almost all of which is wind
energy. However, this is likely an overestimate because not all of the
proposed projects would likely be built. In addition, there is a 1
percent cap on development in the DWMAs and MGSCA and the BLM would
require a 5:1 mitigation ratio on all types of development in the MGSCA
and DWMAs and a 1:1 mitigation ratio outside these areas. Also, the
BLM's draft PEIS on solar energy development has identified four
proposed SEZs, none of which are within the range of the squirrel.
Proposals for new geothermal development on Federal land amount to
only about 0.08 percent of the range of the Mohave ground squirrel.
Although unlikely, if all proposed projects on Federal land, which
makes up about 62 percent of the range, were constructed they would
make up about 2.5 percent of the range. There are also proposals on
private land, which would encompass about 1.2 percent of the squirrel's
range, but many of these are proposed for land that has already been
converted to agriculture. Therefore, under the worst case scenario, if
we assume all proposed projects are constructed, construction of all
renewable energy projects destroys all habitat, and all the habitat
that is lost is suitable for Mohave ground squirrels, then an
additional 3.7 percent of habitat could be lost. However, even in this
worst case, large tracts of habitat would remain untouched, especially
on Federal land.
Livestock grazing occurs throughout portions of the range of the
Mohave ground squirrel. The available information on the effects of
livestock grazing on the Mohave ground squirrel is limited to a study
on dietary overlap between cattle and Mohave ground squirrels; the
study provided no indication that this overlap was adversely affecting
the Mohave ground squirrel. Other studies in the Mojave Desert have
described the general impacts of livestock grazing, particularly
overgrazing, on soils and vegetation, which may result in habitat
degradation but rarely habitat loss. The greatest ground-disturbance
impact of grazing occurs at and near stock tanks and other water
sources where cattle congregate. However, these areas make up a small
percent of the range of the Mohave ground squirrel. The BLM's recent
implementation of public land health standards and guidelines, which
include eliminating or reducing grazing in some areas in the range of
the Mohave ground squirrel, should improve the conditions of the soils
and vegetation, including in the MGSCA and DWMAs. Over time, these
changes are likely to improve the condition of soils and vegetation in
the range of the Mohave ground squirrel.
Agricultural activities are ongoing in the range of the Mohave
ground squirrel. Agricultural development is focused in three areas:
the western Antelope Valley, an area south of EAFB, and the Mojave
River Valley and results in the direct loss of Mohave ground squirrel
habitat. However, this loss is estimated to be less than 1 percent of
the range of the Mohave ground squirrel. Operational impacts in
agricultural areas may also include exposing Mohave ground squirrels
and their forage to pesticide contamination. We found no information
that pesticide use is adversely affecting the Mohave ground squirrel or
its habitat. We also found no information that agricultural development
and associated impacts would likely increase in the western Mojave
Desert. The cost of irrigation has risen to a level that discourages
extensive conversion of desert scrub habitat to agriculture, and
instead, some agricultural lands are being converted to residential and
commercial development.
Mining activities have been ongoing in the western Mojave Desert
for more than a century. Mining activities have impacts to the Mohave
ground squirrel similar to urban and rural development and OHV
recreational use, but on a more localized and limited scale. BLM lands
are open to mining unless otherwise withdrawn; however, the number of
active mines is small when compared to the number of inactive mines.
There is no commercial mining on DOD lands, and there are few large
mines in the range of the Mohave ground squirrel.
Average temperatures have been rising in the western Mojave Desert,
and this trend will likely continue because of climate change. Climate
change may also affect precipitation and the severity, duration, or
periodicity of drought. However, there is a great deal of uncertainty
as to the rate at which the average temperature may increase, and the
effect of climate change on both precipitation and drought. In addition
to the uncertainty associated with how the overall climate of the
Mojave Desert may change, the impact of climate change on the Mohave
ground squirrel will depend on a complex array of other factors,
including how the species and its habitat respond to climate change. In
light of all the factors involved, we are not aware of information that
would allow us to make a meaningful projection on the impact of climate
change on the Mohave ground squirrel.
We now look at the impacts of urban and rural development, OHV
recreational use, transportation infrastructure, military operations,
energy development, livestock grazing, agriculture, mining, and climate
change, cumulatively. Many acres of Mohave ground squirrel habitat have
been lost to these impacts and additional habitat is expected to be
lost in the future. The greatest impacts have resulted from urban and
rural development. Impacts from development as well as those from
agriculture have and continue to be mainly concentrated on private
lands in the southern portion of the range of the Mohave ground
squirrel. Habitat loss due to military operations has been concentrated
in the NTC in the easternmost portion of the squirrel's range. Other
impacts, including heavy-use OHV recreation and transportation
infrastructure, existing and proposed renewable energy development, and
grazing are more dispersed throughout the species' range. Based on a
worst-case analysis, we estimate that in the next 20-30 years about
32.2 percent of the range of the Mohave ground squirrel could be lost.
However, we expect that the actual loss during this timeframe will be
much less because this estimate is based on a series of worst-case
assumptions.
For urban and rural development, we expect the loss of habitat to
be less because California City, which is the largest incorporated area
in the Mojave Desert, has developed very little of its incorporated
area in the past 46 years
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and because the CDFG would likely require mitigation for the loss of
Mohave ground squirrel habitat as part of the permitting process under
CESA (see Factor D, ``State Laws and Regulations'').
For transportation infrastructure, we calculated the loss of
habitat from road construction along the entire highway length, which
includes portions located within incorporated areas and currently
developed areas, thus double counting these impacts within the range of
the Mohave ground squirrel. In addition, we assumed a road-effect zone
for the Mohave ground squirrel, although there may be little or no such
zone for the squirrel, as several studies indicate that the impacts of
highways are generally neutral to slightly positive for small mammals.
For military operations, we assumed that the entire NTC including
the expansion area would be used for ground forces training resulting
in the loss of all Mohave ground squirrel habitat within this area. In
reality, not all of this area will be used for training and some areas
have been set aside as buffer zones needed to shield the training
activities from civilian uses on lands adjacent to the base.
For renewable energy, although the area requested for development
may be large, the actual footprint of the projects is small, much of
the Mohave ground squirrel habitat within the project boundary for wind
and geothermal will not be developed, and many of these projects are
proposed for areas that were previously cleared and used for
agriculture. We also believe the total loss from renewable energy will
be less because habitat loss is frequently mitigated by the acquisition
and enhancement of habitat for the Mohave ground squirrel. In the
squirrel's range, the CDFG may require mitigation for development on
private land and for Federal projects (see Factor D, ``State Laws and
Regulations''). The BLM requires 5:1 mitigation for projects in the
DWMAs and MGSCA and 1:1 elsewhere. Even if the worst case occurs and
all 32.2 percent of the range is eventually lost, we expect that most
of the remaining area will remain relatively undisturbed. More than 80
percent of the remaining land is Federal, and includes the MGSCA and
DWMAs, which are managed at least in part for the Mohave ground
squirrel, and large areas of DOD land, especially on EAFB and NAWS,
which we expect to remain undisturbed in support of the military's
mission. Of particular importance to the Mohave ground squirrel, much
of the remaining lands are contiguous and provide connectivity from the
northern end of the range to well south of SR-58 in the southern
portion of the range. These lands contain most or all the habitat
within the eight important population areas and include habitat that
provides for connectivity among the eight areas.
Based on this information, we conclude that the cumulative impacts
of urban and rural development, OHV recreational use, military
operations, energy development, transportation infrastructure, grazing,
agriculture, mining, and climate change do not currently constitute a
significant threat to the Mohave ground squirrel in relation to the
present or threatened destruction, modification, or curtailment of its
habitat or range, nor do we anticipate that they will pose a threat in
the future.
Factor B: Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
We found no known commercial or recreational utilization of the
Mohave ground squirrel. Scientific and educational activities
associated with the Mohave ground squirrel are controlled by the CDFG
through the issuance of scientific research permits.
Based on our review of the best available scientific and commercial
information, we found no evidence of threats from overutilization for
commercial, recreational, scientific, or educational purposes affecting
the Mohave ground squirrel or potential risks in the future. We
therefore conclude that overutilization for commercial, recreational,
scientific, or educational purposes is currently not a threat to the
Mohave ground squirrel across its range, nor do we anticipate
overutilization for commercial, recreational, scientific, or
educational purposes posing a threat in the future.
Factor C: Disease or Predation
Disease
Although other species of ground squirrels are subject to sylvatic
plague (Foley et al. 2007, p. 1; CA Dept. Public Health 2008, p. 2),
there is no evidence of its presence in Mohave ground squirrels
(Leitner 2005, PowerPoint presentation, slide 11). There is no
information of any other disease present in the Mohave ground squirrel.
Based on our review of the best available scientific information, we
found no research or observational evidence that documents or suggests
that disease is affecting the Mohave ground squirrel (Service and CDFG
1998, p. 2; Leitner presentation, 2005).
Predation
Small rodents such as the Mohave ground squirrel are important prey
for many species. The Mohave ground squirrel is potentially prey to a
host of native predators, including the coyote; American badger; bobcat
(Lynx rufus); various species of raptors, such as the golden eagle,
prairie falcon, and red-tailed hawk (Gustafson 1993, p. 88); common
raven (Boarman 1993, p. 2); and various species of rattlesnakes
(Gustafson 1993, p. 88). In addition, domestic cats and dogs may also
prey on Mohave ground squirrels. Of 36 Mohave ground squirrels radio-
collared in 1995 and 1997, 12 (33 percent) were believed to be lost to
predation (Harris and Leitner 2005, pp. 190-191). Although not directly
observed, mortality from predation was determined from a combination of
blood or toothmarks on radio collars or the discovery of collars at a
raptor or raven perch site. Overall, predation on Mohave ground
squirrels has seldom been observed, and the impact of predation on the
species is not known. Small rodents are important prey for many of the
species listed above, and predation on small rodents, including the
Mohave ground squirrel, can be high.
The coyote is a common predator in the western Mojave Desert.
Although the coyote is likely a predator of the Mohave ground squirrel,
we found no recorded observations of coyotes preying on Mohave ground
squirrels or fecal analysis of coyote scat that contained remains of
Mohave ground squirrels. In addition, we found no information
documenting that the coyote population has increased or is expected to
increase in the western Mojave Desert, or the level of predation by the
coyote on the Mohave ground squirrel has increased or is expected to
increase, or that coyote predation is having an adverse impact on the
species.
The increased presence of domestic dogs and cats in the western
Mojave Desert may impact the Mohave ground squirrel. Feral or free-
ranging domestic dogs have been identified as potential predators of
the Mohave ground squirrel (D. LaBerteaux, cited in Gustafson 1993,
Appendix, p. 86). The BLM (BLM et al. 2005, chapter 3, p. 65) noted
``feral dogs are a problem in several areas'' of the western Mojave
Desert ``where they may kill Mohave ground squirrels.'' The BLM found
that dogs are most common in the habitat adjacent to urbanized areas
(BLM et al. 2005, chapter 3, p. 96). For example, BLM survey results
showed that dog sign occurred on 88
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percent of the transects surveyed in proximity to urbanized areas but
occurred on less than 1 percent of the transects surveyed in the
undeveloped Fremont-Kramer and Superior-Cronese DWMAs (BLM et al. 2005,
chapter 3, p. 104). For those transects within the range of the Mohave
ground squirrel, 4 percent had dog sign (BLM et al. 2005, chapter 3, p.
156). Although these data indicate that dogs, based on the presence of
sign, occur in desert habitats within the range of the Mohave ground
squirrel, Leitner (2005 presentation) indicated that no data have been
collected that document that dogs have an impact on the species. In our
review of the available information, we did not find any indication
that feral or domestic dogs prey on Mohave ground squirrels or dig up
Mohave ground squirrel burrows. In the WEMO Plan, the BLM stated that
failure to implement a feral dog management plan is not likely to
adversely affect the Mohave ground squirrel, as ``feral dog predation
has not been documented as a significant threat'' (BLM et al. 2005,
chapter 4, p. 153). Therefore, we conclude that domestic or feral dogs
are not a major predator of the Mohave ground squirrel and their rate
of predation is not likely to increase in the future.
Domestic cats may have increased near urban expansion areas in the
western Mojave Desert. Domestic cats are efficient predators of small
birds and mammals (Harrison 1992, p. 10). Gustafson (1993, p. 30-31)
postulated that domestic cats may kill Mohave ground squirrels.
However, Leitner (2005 presentation) stated there is no documentation
of the impact of predation by domestic cats on Mohave ground squirrels.
Although it is likely that domestic cats have increased in the western
Mojave Desert with the increased human population in the past few
decades, we were unable to find information documenting that domestic
cats prey on Mohave ground squirrels.
The common raven is a likely predator of the Mohave ground
squirrel. Harris and Leitner (2005, pp. 190-191) found empty radio
collars from Mohave ground squirrels under raven perch sites and
concluded this was evidence of predation by common ravens on Mohave
ground squirrels. Common ravens kill many types of animals for food,
including ground squirrels (Boarman 1993, p. 2). Kochert et al. (1976,
in Knight and Call 1980, p. 17) reported that Townsend ground squirrels
(Urocitellus townsendii) in Idaho comprised 93 and 70 percent of the
food biomass of nesting ravens during a 2-year study.
The common raven population increased more than 700 percent in the
western Mojave Desert from 1986 to 2004 (Boarman and Kristan 2006, p.
2; Service 2008, p. A-16), likely in response to increased urbanization
and recreational use, which provide common ravens with an artificial
source of reliable and widespread food, water, nest sites, roost sites,
and perch sites (Boarman 2002, p. 1). In most locations, human-created
nest, roost, and perch sites, including transmission line towers,
telephone and streetlight poles, buildings, billboards, and fences,
provide the common ravens with previously unavailable high perches,
which allow them to hunt and scavenge more effectively, or with less
energy expenditure than required by flight or from a low perch (Boarman
1993, p. 2).
Although common ravens likely prey on Mohave ground squirrels, and
the amount of predation has likely increased as the population of
ravens has increased, the available information does not indicate that
this level of predation is having an adverse effect on Mohave ground
squirrel populations.
Summary of Factor C
In summary, we found no information that disease is a threat to the
Mohave ground squirrel throughout its range. Regarding predation,
beyond the general knowledge of natural and potential predators of the
Mohave ground squirrel, we found no information on the observance or
extent of predation by coyotes, domestic dogs or cats on the Mohave
ground squirrel, and no information suggesting that predation is
affecting Mohave ground squirrel abundance, distribution, or long-term
survival. We did find circumstantial information that predation by the
common raven likely occurs on the Mohave ground squirrel. We also found
information that the number of common ravens in the western Mohave
Desert has increased substantially in the last few decades. We
acknowledge that the level of predation by the common raven on the
Mohave ground squirrel may have increased, but the available
information does not indicate that this level of predation is adversely
affecting Mohave ground squirrel abundance, distribution, or long-term
survival. Therefore, based on our review of the best available
scientific and commercial information, we conclude that predation is
currently not a significant threat to the Mohave ground squirrel
throughout its range, nor do we anticipate predation posing a threat in
the future.
Factor D: The Inadequacy of Existing Regulatory Mechanisms
The Act requires us to examine the adequacy of existing regulatory
mechanisms with respect to those existing and foreseeable threats that
may place the Mohave ground squirrel in danger of becoming either
endangered or threatened. Existing regulatory mechanisms that provide
some protection for the Mohave ground squirrel include local land use
ordinances and processes, State laws and regulations, and Federal laws
and regulations. The habitat of the Mohave ground squirrel spans
private lands, local government lands, State lands (California State
Parks, CDFG, and California State Land Commission), and Federal lands
(BLM, DOD, National Park Service (NPS), and U.S. Forest Service (USFS))
in California.
Local Land Use Ordinances and Processes
Approximately 31 percent of the range of the Mohave ground squirrel
is privately owned, or owned by local governments. We found little in
the way of local planning and enforceable zoning regulations specific
to the Mohave ground squirrel. Approximately 11.9 percent of the range
of the Mohave ground squirrel lies within San Bernardino County, but
the County has regulatory authority over only a portion of these lands.
The County of San Bernardino online ``Biotic Resources Overlay Map''
includes information to assist both the property developer and County
land use planner in identifying lands that may support the Mohave
ground squirrel. If a proposed discretionary project is within this
overlay area, the County would accept an application for development
only after a focused survey for the Mohave ground squirrel has been
completed (Zias-Roe 2010, pers. comm.). If the survey results are
positive, the County would require demonstration of compliance with
CESA. Similar planning tools are used by municipalities such as the
Town of Apple Valley (2009, p. III-50 of the General Plan) for
discretionary projects. The Mohave ground squirrel is usually not
considered when implementing actions such as issuing building or
grading permits.
State Laws and Regulations
California laws and regulations that may benefit the Mohave ground
squirrel include CESA and the California Environmental Quality Act
(CEQA) (Public Resources Code sections 21000-21177). These laws provide
broad
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authority to regulate and protect wildlife within the State, specific
authority for lands directly owned by the State, and specific authority
to require reduction of take of the species through minimization and
mitigation of impacts from discretionary actions at a local or State
government level.
The State of California has broad authority to regulate and protect
wildlife within its borders. The mission of the CDFG is ``to manage
California's diverse fish, wildlife, and plant resources, and the
habitats upon which they depend, for their ecological values and for
their use and enjoyment by the public'' (CDFG 2005, p. 1). The CDFG
does this through a variety of actions, including enforcing hundreds of
laws and regulations related to fish, wildlife, and habitat; managing
lands at wildlife areas, ecological reserves, and public access sites
for ecological and recreational uses; and collecting and analyzing
scientifically based data on the distribution and abundance of fish,
wildlife, and native plant species and the natural communities and
habitats in which they live. When implemented in the range of the
Mohave ground squirrel, these actions benefit the species.
One California law that addresses the conservation and protection
of the Mohave ground squirrel is CESA, which was enacted in 1985. The
Mohave ground squirrel is listed as threatened under CESA; CESA defines
a threatened species as a native species that, although not presently
threatened with extinction, is likely to become an endangered species
in the foreseeable future in the absence of special protection and
management efforts. CESA also declares that it is the policy of the
State to conserve, protect, restore, and enhance any endangered or
threatened species and its habitat. Take, as defined under CESA, of a
threatened or endangered species is prohibited without first obtaining
authorization from the CDFG.
Because the Mohave ground squirrel is a threatened species under
CESA, anyone wishing to capture or otherwise take a Mohave ground
squirrel for scientific purposes must first obtain a memorandum of
understanding (MOU) or a permit from the CDFG as described under
California Fish and Game Code 2081(a) (CDFG 2003, p. 1). The issuance
of the MOU or permit is a discretionary action by the CDFG. Under the
California Fish and Game Code, the CDFG is charged with ensuring that
any action it authorizes does not jeopardize the continued existence of
the species. Therefore, the CDFG is not allowed by regulation to issue
a permit that would result in the overutilization of the Mohave ground
squirrel for scientific purposes.
California Fish and Game Code section 2081, enacted in 1999, states
that the CDFG may authorize, by permit, the take of an endangered and
threatened species, if the take is incidental to an otherwise lawful
activity and the impacts of the take are minimized and fully mitigated.
Although CESA does not apply to Federal land management agencies
conducting actions on Federal lands, it generally does apply to actions
taken by non-Federal entities. Therefore, compliance with CESA is
needed for many actions occurring in the range of the Mohave ground
squirrel, including on Federal land. In addition, the State listing of
the Mohave ground squirrel helps focus Federal land managers' attention
on the species and consider impacts to the species when developing
actions. Most Federal land managers would prefer to manage for a
species to ensure it does not require the protections of the Act.
Because CESA prohibits the taking of the Mohave ground squirrel
without obtaining a permit, the CDFG requires that a standard survey
protocol, which was developed by the CDFG in 1987 (Gustafson 1993, p.
463) and revised in 2003, be used to determine the presence or absence
of the Mohave ground squirrel on lands proposed for development.
Therefore, the results obtained with the protocol are a critical
component of the decision making process, and most of the information
available on the distribution and abundance of the Mohave ground
squirrel is based on the same results. The survey protocol specifies
that a CDFG-approved, qualified biologist conduct a visual survey of
the proposed project site. If the results are negative, a series of
live grid traps are set during three periods. If the results for Mohave
ground squirrels are negative after implementation of the survey
protocol, the CDFG stipulates that the project site contains no Mohave
ground squirrels, and development may occur without an incidental take
permit and mitigation (CDFG 2003, p. 3). If Mohave ground squirrels are
present at a proposed development, then CESA and California Fish and
Game Code section 2081 require that the impacts be minimized and fully
mitigated. The CDFG generally requires securing and managing existing
habitat at another location for the Mohave ground squirrel. Thus, for
every discretionary project with positive survey results,
implementation of the proposed development with mitigation yields a net
loss of acres of habitat for the Mohave ground squirrel, but the lands
acquired for mitigation are managed to improve their habitat value and
are secured in perpetuity for the Mohave ground squirrel.
One major difference between CESA and the Act is that there is no
requirement under CESA to develop and implement a recovery plan for a
State-listed species. Consequently, with no recovery plan, there is no
written guidance for Federal, State, and local agencies and the public
to know what actions to implement and where to implement them to
achieve the State's policy to conserve, protect, restore, and enhance
the Mohave ground squirrel and its habitat.
In evaluating the Mohave ground squirrel protocol, some scientists
have identified potential problems with the protocol that raise into
question the accuracy of the current survey technique (Brooks and
Matchett 2002, p. 172). The survey protocol may yield false negative
results or undersample the population. Mohave ground squirrels are
difficult to trap, even in locations where they have been sighted (Hoyt
1972, p. 7). Mohave ground squirrels have been observed approaching
traps but not entering them (Leitner 2009, pers. comm.). In some cases,
only a few squirrels have been trapped while several had been seen or
heard calling in the same area (Urban et al. 2010, p. 1). In addition,
the grid trap arrangement is not necessarily the best trapping method
to use for detecting rare small mammals. For example, in comparing grid
and transect trap arrangements for small mammals, transect arrangements
yielded more total captures, more individual captures, and more species
than grid arrangements (Pearson and Ruggiero 2003, p. 457). The
differences between the two methods tend to be greatest when small
mammals are least abundant (Pearson and Ruggiero 2003, p. 457), as may
be the case with the Mohave ground squirrel. Recently, a video survey
method was compared to the live trapping survey protocol at two
locations. The Mohave ground squirrel detection rate for the video
method was greater than for the trapping protocol (Delaney 2009, p. 12)
(see ``Abundance and Trend'' section).
The CDFG acknowledges that a negative survey result does not mean
that the Mohave ground squirrel does not occur on the site, or that
take will not occur (CDFG 2003, p. 3). The survey protocol, including
the trapping component of the protocol, may result in a false negative
finding (e.g., the Mohave ground squirrels may be present but the
available data from the
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survey protocol indicates they are not present). The purpose of the
survey protocol is to determine presence and therefore if take will
occur. Its purpose is not to provide population information on
population size, status, or trend.
In summary, CESA provides some protection for the Mohave ground
squirrel from take and habitat loss. However, the benefit of CESA to
the squirrel may depend on the ability to detect the species on a
proposed development site. If squirrels are present on a site but not
detected with the survey protocol, which is known to occur based on
subsequent observations, then the project is implemented with no
mitigation for the Mohave ground squirrel under CESA. If a project
proponent assumes presence of the Mohave ground squirrel at a project
site or if squirrels are detected during the survey protocol, then CESA
requires mitigation for the take of the Mohave ground squirrel. Thus,
CESA provides some benefit to the Mohave ground squirrel and its
habitat.
CEQA is a regulatory mechanism that affords protection for the
Mohave ground squirrel in certain circumstances. CEQA requires review
of environmental impacts for any proposed discretionary project that is
undertaken, funded, or permitted by a State or local governmental
agency, and public disclosure of these findings. Section 15065 of the
CEQA guidelines requires a finding of significance if the project has
the potential to ``reduce the number or restrict the range of a rare
(threatened) or endangered plant or animal.'' The Mohave ground
squirrel is such a species, because as stated above it is listed as
threatened by the State of California. In general, if a proposed
project in Mohave ground squirrel habitat requires a discretionary
permit from a State or local agency, that public agency is required to
prepare a public document under CEQA that analyzes the impacts of the
proposed action on the species and requires mitigation for the impacts.
However, if economic, social, or other conditions make it infeasible to
mitigate one or more significant effects of a project on the species,
the project may nonetheless be carried out or approved at the
discretion of a public agency if the project is otherwise permissible
under applicable laws and regulations (CEQA Guidelines section 15093),
even though the project may cause significant environmental damage,
such as destruction of a listed species or its habitat.
Although CEQA may provide protection for the Mohave ground squirrel
in certain circumstances, there are several statutory and categorical
exemptions to CEQA which exempt proposed projects that are undertaken,
funded, or permitted by local or State agencies from the requirements
of public disclosure and mitigation. These include certain mass transit
projects, certain planning documents, certain pipeline projects,
certain ministerial (non-discretionary) projects (Title 14 California
Code of Regulations, chapter 3, Article 18, sections 15260 to 15285),
grazing (Rebecca Jones 2010, in litt.), and in-fill development
projects (Article 19, sections 15300 to 15333). Also exempt are
projects that are approved by popular vote that do not involve a public
agency-sponsored initiative (Title 14 California Code of Regulations,
chapter 3, Article 20, section 15378).
The exemption of ministerial-permitted projects is an important
consideration in evaluating the level of protection of the Mohave
ground squirrel and its habitat afforded by CEQA. On private land, CEQA
applies only to discretionary actions, such as major changes in zoning
or requests for a conditional use permit. Building or grading permits
or other development projects with minor, or no, changes to existing
land use or zoning designations are considered ministerial by the local
development agencies and are not subject to CEQA. Although minor on an
individual basis, cumulatively, these activities can result in the take
of the species and the loss, fragmentation, and degradation of habitat
with no mitigation under CEQA. These activities, however, would still
be subject to the requirements of CESA.
Another California law that could benefit the Mohave ground
squirrel is the Natural Communities Conservation Planning Act (NCCPA).
NCCPA provides for voluntary cooperation among the CDFG, landowners,
and other interested parties to develop natural community conservation
plans (NCCPs) that provide for early coordination of efforts to protect
listed species or species that are not yet listed. NCCPA identifies and
provides for the regional or area-wide protection of plants, animals,
and their habitats, including listed species, while allowing compatible
and appropriate development activity. NCCPA could not only benefit the
Mohave ground squirrel, but could also benefit local communities in the
western Mojave Desert, which, under the NCCPA, could obtain
authorization to take the Mohave ground squirrel while allowing for
reasonable development. There is no NCCP for the Mohave ground squirrel
at this time; however, there is one under development for renewable
energy in the California desert. If the renewable energy NCCP is
finalized and implemented, some areas inhabited by the Mohave ground
squirrel would be included in the plan area.
In addition to these laws and regulations, California also manages
lands in the range of the Mohave ground squirrel for native habitat.
These lands include about 22,000 ac (8,900 ha) managed by the
California Department of Parks and Recreation and 15,000 ac (6,070 ha)
managed by the CDFG.
Federal Laws and Regulations
Federal agencies are responsible for managing approximately 66
percent of the range of the Mohave ground squirrel (Defenders of
Wildlife and Stewart 2005, pp. 39-40). The Federal agencies with the
largest land management authority for these lands are the BLM and the
DOD (see Table 1 and Factor A).
Several Federal laws and regulations that may benefit the Mohave
ground squirrel include the National Environmental Policy Act of 1969
(42 U.S.C. 4321 et seq.), as amended (NEPA); Federal Land Policy and
Management Act of 1976 (43 U.S.C. 1701 et seq.) (FLPMA); Public
Rangelands Improvement Act of 1978 (43 U.S.C. 1752 et seq.); Wild Horse
and Burro Protection Act of 1971 (16 U.S.C. 1331 et seq.); and the
Sikes Act Improvement Act (16 U.S.C. 670a-670o), as amended (Sikes
Act). These laws provide authority to conserve habitat and mitigate for
adverse impacts to habitat, including habitat for the Mohave ground
squirrel. In addition, if the Mohave ground squirrel occurs on the same
patch of habitat as a federally listed species (e.g., desert tortoise
(Gopherus agassizii) or Astragalus jaegerianus (Lane Mountain milk-
vetch)), the Mohave ground squirrel may benefit from the protections
afforded these species under the Act.
Bureau of Land Management
About 37 percent of the land (1,804,139 ac (730,112 ha)) within the
range of the Mohave ground squirrel is administered by the BLM
(Defenders of Wildlife and Stewart 2005, pp. 39-40). As a Federal
agency, whenever BLM proposes to implement or authorize any action on
lands that it manages, it must comply with NEPA. NEPA requires all
Federal agencies to formally document and publicly disclose the
environmental impacts of their proposed actions and management
decisions.
In addition, 40 CFR 1500.2 requires all Federal agencies, to the
fullest extent possible, to use all practicable means, consistent with
the requirements of NEPA and other essential considerations of national
policy, to
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restore and enhance the quality of the human environment and avoid or
minimize any possible adverse effects of their actions upon the quality
of the human environment. When implementing NEPA within the range of
the Mohave ground squirrel, all Federal agencies must consider their
potential impacts on the species and identify and consider appropriate
mitigation measures.
FLPMA is the primary Federal law governing most land uses on BLM
lands. FLPMA established a public land policy for the BLM; it provides
for the management, protection, development, and enhancement of the BLM
lands. Public lands are managed for multiple use and sustained yield.
Under its multiple use mandate, the BLM allows grazing, mining, OHV
use, energy production, and other uses on public lands. The BLM also
has the flexibility under FLPMA to establish and implement special
management areas such as ACECs and research natural areas, where the
BLM can limit or exclude surface disturbance activities that adversely
affect sensitive species, such as the Mohave ground squirrel.
FLPMA directs the development and implementation of resource
management plans (RMPs), which direct management at a local level, and
requires public notice and participation in the formulation of such
plans and programs for the management of BLM lands. RMPs authorize and
establish allowable resource uses, resource condition goals and
objectives to be attained, program constraints, general management
practices and sequences, intervals and standards for monitoring and
evaluating RMPs to determine effectiveness, and the need for amendment
or revision (43 CFR 1601.0-5(k)).
Section 601 of FLPMA was written specifically for the CDCA, which
includes the western Mojave Desert. In this section, Congress noted the
fragility of the California desert ecosystem that is ``easily scarred
and slow to heal; the historical, scenic, archeological, environmental,
biological, cultural, scientific, educational, recreational, and
economic resources in the California desert; and that certain rare and
endangered species of wildlife, plants, and fishes, and numerous
archeological and historic sites, are seriously threatened by air
pollution, inadequate Federal management authority, and pressures of
increased use, particularly recreational use, which are certain to
intensify because of the rapidly growing population of southern
California.'' Congress charged the BLM with developing and implementing
an RMP for the CDCA that provides for the immediate and future
protection and administration of the public lands in the California
desert within the framework of a program of multiple-use and sustained
yield, and the maintenance of environmental quality. Within the range
of the Mohave ground squirrel, the current BLM land management
documents are the California Desert Conservation Area (CDCA) Plan 1980,
as amended (BLM 1999) and other amendments to the CDCA Plan, including
the WEMO Plan and EIS (BLM et al. 2005). The WEMO Plan is the RMP for
the western portion of the CDCA.
The Mohave ground squirrel is designated as a sensitive species on
BLM lands. The management guidance for special status species under BLM
Manual 6840-Special Status Species Management states that ``Bureau
sensitive species will be managed consistent with species and habitat
management objectives in land use and implementation plans to promote
their conservation and to minimize the likelihood and need for listing
under the ESA'' (BLM 2008, p. 05V). BLM Manual 6840 further requires
that RMPs should address sensitive species, and that implementation
``should consider all site-specific methods and procedures needed to
bring species and their habitats to the condition under which
management under the Bureau sensitive species policies would no longer
be necessary'' (BLM 2008, p. 2A1).
The WEMO Plan is the up to 30-year RMP whose boundary includes most
of the current habitat of the Mohave ground squirrel. One of the
purposes of the WEMO Plan was to develop and implement management
strategies that would conserve the Mohave ground squirrel throughout
the western Mojave Desert (BLM et al. 2005, p. ES-1). This RMP contains
specific measures pertinent to the management of the Mohave ground
squirrel and its habitat. The BLM designated the MGSCA, a wildlife
habitat management area (WHMA), on BLM lands in the northern part of
the species' range (BLM et al. 2005, chapter 2, p. 203; LaPre 2009, in
litt.). Within the MGSCA boundary, land ownership is BLM (1,308,877 ac
(529,686 ha)) with private land (420,000 ac (169,969 ha)) scattered
among the BLM land (BLM et al. 2005, chapter 2, p. 203). Thus, about 75
percent of the land within the MGSCA is subject to the BLM's management
protections for the MGSCA.
Within the central and southern portion of the range of the Mohave
ground squirrel are three ACECs, the Fremont-Kramer DWMA (513,918 ac
(207,976 ha)), the Desert Tortoise Research Natural Area (DTNA), which
is contained within the Fremont-Kramer DWMA, and the Superior-Cronese
DWMA (641,917 ac (259,776 ha)) (BLM et al. 2005, chapter 2, p. 13).
About 55 percent of the Fremont-Kramer, 59 percent of the Superior-
Cronese, and 92 percent of the DTNA lands within the ACEC boundaries
are BLM lands. The BLM manages these ACECs at a greater level of
protection for wildlife and habitat than the MGSCA. It does not allow
certain land uses, such as solar energy development, in ACECs, and
acquires private land within DWMA boundaries in areas that overlap the
range of the Mohave ground squirrel (BLM et al. 2005, chapter 2, pp.
28, 70). The Mohave ground squirrel will benefit from the management of
these three ACECs and the MGSCA because they are contiguous with each
other, which will facilitate management of these lands as blocks of
unfragmented habitat outside military bases (see Map 2).
The Public Rangelands Improvement Act established a national policy
and commitment to improve the conditions on public rangelands. Its goal
is to improve range condition, which relates to wildlife habitat and
plant communities. The BLM has specific regulatory authority for
grazing management provided at 43 CFR 4100 (Regulations on Grazing
Administration Exclusive of Alaska). Livestock grazing permits and
leases contain terms and conditions to achieve management and resource
condition objectives on the BLM lands, and to ensure that habitats are,
or are making significant progress toward, being restored or maintained
for BLM special status species (43 CFR 4180.1(d)), which include the
Mohave ground squirrel. Examples of the actions BLM has taken to
accomplish this goal include: Closing some sheep allotments, removing
sheep from allotments in the MGSCA when ephemeral plants are no longer
the primary forage used by sheep, eliminating ephemeral grazing for
cattle in the DWMAs, and excluding cattle grazing in the spring in
DWMAs when annual plant productivity is low (BLM et al. 2005 chapter 2,
pp. 131-135).
In 1964, Congress enacted the Wilderness Act, with the intent of
establishing a National Wilderness Preservation System composed of
federally owned wilderness areas to be protected in their natural
condition for the use and enjoyment of the people of the United States.
A variety of activities are prohibited by the Wilderness Act within
designated wilderness areas.
As mentioned under Factor A, part or all of 14 designated
wilderness areas are on BLM lands and in the range of the
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Mohave ground squirrel. The Wilderness Act protects these areas from
various forms of development and human activities that are stressors
for the Mohave ground squirrel; however, the areas designated as
wilderness within the range of the Mohave ground squirrel comprise
about 4.6 percent of the species' range and are not contiguous. These
areas include steep slopes and rocky substrates that would not provide
suitable habitat for the Mohave ground squirrel but would contribute to
connectivity among squirrel habitat.
The Wild Horse and Burro Protection Act directs the BLM to protect
these animals on public lands where they occurred when the law was
enacted, and to manage them by removing excess animals to restore a
thriving natural ecological balance to the range. This law enables the
BLM to remove nonnative wild horses and burros that are degrading or
destroying habitat within the range of the Mohave ground squirrel.
To manage motorized access on BLM lands within the range of the
Mohave ground squirrel, the FLPMA and its implementing regulations
direct the BLM to locate trails in a manner to minimize impacts to the
physical resources (i.e., soils, watershed, vegetation, air, and other
resources), and to minimize harassment of wildlife or significant
disruption of wildlife habitats (43 CFR 8342.1). To manage for the
Mohave ground squirrel and other species, the BLM has implemented a
program of OHV route obliteration and restoration and the signing of
open routes to keep OHV activities aligned with what is permitted. In
the central portion of the Mohave ground squirrel's range, the BLM
implemented the Rand Mountain Fremont Valley Plan (Rand Plan) on 65,020
ac (26,313 ha) between Ridgecrest and California City, which includes
an area popular with OHV enthusiasts. The Rand Plan adopted a motorized
vehicle access network, expanded the Rand ACEC by 13,120 ac (5,309 ha),
reduced the multiple use class from Class M to Class L, acquired
private lands, and withdrew land from mineral entry. Class L lands are
intended to support limited use by activities that degrade the value of
the land and to protect sensitive, natural, scenic, ecological, and
cultural resource values. Class M lands have moderate use, and provide
for a controlled balance between higher intensity uses and resource
protection (BLM et al. 2005, chapter 3, p. 3). The BLM considered
implementing the Rand Plan a high priority for Mohave ground squirrel
conservation (BLM et al. 2005, chapter 3, p. 170) as it reduces impacts
to the Mohave ground squirrel and its habitat from OHV recreation in
the Plan area.
Both FLPMA and the Mineral Leasing Act give the BLM the legal
authority to regulate and condition energy permits. The Energy Policy
Act of 2005 (42 U.S.C. 15801 et seq.) orders the identification of
renewable energy sources and provides incentives for their development
(42 U.S.C. 15851). This law and Presidential Executive Order 13121
direct the production, purchase, and facilitation of development of
renewable energy products by Federal entities and land management
agencies. The ``Energy Development'' section of Factor A describes the
development and operation of renewable energy projects, including
recent increases in solar, wind, and geothermal energy development. All
of these activities require ground disturbance, infrastructure, and
ongoing human activities that could adversely affect the Mohave ground
squirrel on the landscape.
In summary, the BLM manages about one-third of the range of the
Mohave ground squirrel. Under FLPMA, the BLM has designated three ACECs
and a MGSCA, which are contiguous and will facilitate management of
these lands (see Factor E). The BLM has a mandate to manage BLM lands
for multiple-use, and has broad regulatory authority to plan and manage
all land use activities on public lands, including energy development,
OHV recreation, grazing, and other activities. As described in Factor
A, these activities have the potential to impact the Mohave ground
squirrel and its habitat. The BLM has developed mitigation measures for
many of these activities that will reduce or eliminate the magnitude
and severity of the impacts to Mohave ground squirrel habitat. In some
cases, the BLM limits or prohibits activities on BLM lands with special
designations because of incompatibility with those designations.
Department of Defense
The U.S. Army's Fort Irwin, the U.S. Navy's NAWS, and the U.S. Air
Force's EAFB include about 1,683,095 ac (681,127 ha) or 31.6 percent of
the Mohave ground squirrel range. Additional DOD lands in the Mohave
ground squirrel range (Air Force Plant 42 in Palmdale and Cuddeback
Lake Air Force Range northeast of EAFB) comprises about 0.1 percent of
the species' habitat. Three of the Mohave ground squirrel important
population areas (Leitner 2008, p. 34) occur partly or entirely on
these DOD lands (see Map 2). Part of the Coso Range-Olancha important
population area is on NAWS, part of the Coolgardie Mesa-Superior Valley
important population area is on Fort Irwin, and the EAFB important
population area is within this military base.
As Federal agencies, these DOD bases must formally document and
publicly disclose the environmental impacts of their proposed actions
and management decisions. Fort Irwin recently expanded its boundaries.
Much of the expansion area is in the range of the Mohave ground
squirrel. During the NEPA process, DOD identified that the proposed
expansion would impact about 123,000 ac (49,777 ha) of desert tortoise
habitat, of which, about 83,000 ac (33,589 ha) is in designated
critical habitat and within the Superior-Cronese DWMA (Charis 2005, p.
ES-9). Of the four known populations of Lane Mountain milk-vetch, the
expansion and operation of the NTC would not impact the 1,283 ac (519
ha) NASA-Goldstone population, but would impact 66 percent of the 5,499
ac (2,225 ha) Brinkman Wash-Montana Mine population and 20.25 percent
of the 4,796 ac (1,941 ha) Paradise Valley population (U.S. Fish and
Wildlife Service 2004, pp. 24, 53). The 9,775 ac (3,956 ha) Coolgardie
Mesa population is located outside the Fort Irwin boundary.
To help offset the loss of habitat of the desert tortoise and Lane
Mountain milk-vetch, the Army established two conservation areas for
the Lane Mountain milk-vetch totaling 6,770 ac (2,740 ha) (Charis 2005,
pp. 4-21 and 4-22); acquired private lands in the Fremont-Kramer and
Superior-Cronese DWMAs (Fort Irwin 2003, pp. 2-31); and purchased fee
land and associated assets and improvements associated with the 26,314
ac (10,649 ha) Harper Dry Lake grazing allotment and retired cattle
grazing on these lands (Fort Irwin 2003 pp. 2-34). The acquired private
lands in the Fremont-Kramer and Superior-Cronese DWMAs (see Map 2) and
the grazing allotment comprise 8.2 and 0.5 percent of the range of the
Mohave ground squirrel, respectively, whereas the expansion area
comprises 75,300 ac (30,473 ha) or 1.4 percent of the range of the
Mohave ground squirrel and the NTC including the expansion area within
the range of the Mohave ground squirrel comprises 435,978 ac (176,435
ha) or 8.2 percent of the range of the Mohave ground squirrel (see
Factor A, ``Military Operations''). When the total area of the acquired
mitigation lands is compared to the total area of expansion lands, the
mitigation ratio of
[[Page 62249]]
acquired lands to expansion lands is about 5.8:1.
The DOD must comply with the Sikes Act and its implementing
regulations. This law requires the DOD to develop cooperative plans for
conservation and rehabilitation programs for natural resources on
military bases and to establish outdoor recreation facilities. Each
base prepares an Integrated Natural Resources Management Plan (INRMP)
that provides for fish and wildlife habitat improvements or
modifications; range rehabilitation where necessary to support
wildlife; control of OHV traffic; and specific habitat improvement
projects and related activities and adequate protection for species of
fish, wildlife, and plants considered threatened or endangered.
Fort Irwin prepared an INRMP in 2006 that included conservation,
protection, and management actions for the Mohave ground squirrel. The
Fort Irwin INRMP recognized the expansion would adversely affect the
Mohave ground squirrel (Fort Irwin 2006, pp. 135-136) and proposed
measures in addition to the mitigation measures in the Fort Irwin
Expansion FEIS. Some of these measures included retiring a grazing
allotment near Harper Dry Lake in the central portion of the range of
the Mohave ground squirrel; continuing research on Mohave ground
squirrel populations at Fort Irwin and the Goldstone Complex, an area
within Fort Irwin used by NASA and protected from military activities;
and surveying for the Mohave ground squirrel in the east important
population area (Fort Irwin 2006, pp. 136-146).
NAWS is currently revising its INRMP. Its current INRMP states that
its objectives for the Mohave ground squirrel include ``maintain[ing]
viable populations'' and ``minimize[ing] impacts and protect[ing] known
and potential endangered and sensitive species habitats to the maximum
extent practicable'' (NAWS 2000, pp. 126-127).
The Air Force completed its INRMP for EAFB in 2008. Based on this
document, the Air Force is continuing its implementation of surveys for
the Mohave ground squirrel and implementing specific management
measures to minimize or eliminate impacts to Mohave ground squirrel
habitat from ongoing military operations on the base (EAFB 2008a, pp.
73-76). Also, conservation measures for the federally threatened desert
tortoise and its designated critical habitat included in the INRMP will
benefit the Mohave ground squirrel.
Environmental Protection Agency
The Clean Air Act of 1970 (42 U.S.C. 7401 et seq.) directs the EPA
to develop and enforce regulations to protect the general public from
exposure to airborne contaminants that are known to be hazardous to
human health. In 2007, the U.S. Supreme Court ruled that gases that
cause global climate change are pollutants under the Clean Air Act, and
the EPA has the authority to regulate carbon dioxide and other heat-
trapping gases (Massachusetts et al. v. EPA 2007 [Case No. 05-1120]).
EPA policies to implement the Clean Air Act in addressing climate
change caused by greenhouse gas emissions are still evolving. However,
our status review did not reveal information that indicates that
climate change is a significant threat to the Mohave ground squirrel
throughout its range (see Factor A).
Other Federal Agencies
The USFS and NPS have management authority for less than 2 percent
of the habitat of the Mohave ground squirrel. For the USFS, these lands
are within Federal wilderness areas on the east side of the Sierra
Nevada. For the NPS, these lands are within Death Valley National Park.
Under the Wilderness Act of 1964 (16 U.S.C. 1131-1136), motorized
activities, including motorized travel, energy development, mining, and
other mechanized activities, are prohibited. Although grazing may be
permitted in Federal wilderness areas, the USFS does not permit grazing
in the Owens Peak and Sacatar Trail wilderness areas, which are within
the range of the Mohave ground squirrel.
The amount of USFS lands within the range of the Mohave ground
squirrel is very small, about 4,400 ac (1,781 ha) or 0.08 percent, and
occurs at the west and northwest edge of the species' range. A strip of
about 44,026 ac (17,824 ha), which is less than 1 percent of the range
of the Mohave ground squirrel, occurs on NPS land along the northeast
edge of the range of the species.
Summary of Factor D
Several laws and regulations, including CEQA, CESA, FLPMA, Sikes
Act, and NEPA, provide varying levels and aspects of protection of or
beneficial measures for the Mohave ground squirrel and its habitat at
the local, State, and Federal level. Many of these regulatory
mechanisms also encourage habitat protection for the Mohave ground
squirrel and provide tools to implement these habitat protections.
Although no single law or regulation provides overall protection of the
Mohave ground squirrel and its habitat throughout its range, we find
that, cumulatively, when implemented, existing regulations provide for
the long-term survival of the species. Our assessment of threats based
on the best available scientific and commercial information regarding
the loss and degradation of the range or habitat of the Mohave ground
squirrel under Factor A, and fragmentation and mortality as discussed
under Factor E lead us to conclude that the inadequacy of existing
regulatory mechanisms is not a threat to the Mohave ground squirrel.
Therefore, based on our review of the best available scientific and
commercial information, we conclude that the Mohave ground squirrel is
not currently threatened by inadequate regulatory mechanisms throughout
its range, nor do we anticipate inadequate regulatory mechanisms posing
a threat in the future.
Factor E: Other Natural or Manmade Factors Affecting the Continued
Existence of the Species
Direct Mortality
As discussed in Factor A, several actions/stressors may result in
mortality of the Mohave ground squirrel. Heavy equipment used in the
construction of urban and rural development, roads, energy facilities,
agricultural areas, and mines may crush Mohave ground squirrels above
ground and in their burrows. The intensive use of vehicles in OHV
management areas and wheeled and tracked vehicles used off road in
military operations may have similar impacts. Although we recognize
that mortality of Mohave ground squirrels from these sources occurs, we
found few documented reports of Mohave ground squirrels being run over
by vehicles (Threloff 2007, in litt.) or heavy equipment and no reports
of them being killed in their burrows. The level of mortality is likely
a function of a number of complex variables including squirrel density,
habitat quality, time of year, and type and intensity of human
activity. Mortality is probably highest in areas of preferred habitat
where heavy equipment is used, habitat is cleared, and human activity
is high (e.g., urban development, road construction), as the entire
area is graded and replaced with man-made structures. Roads may be
another important source of direct mortality, and depending on factors
such as location, road width, and traffic rates, roads could result in
reduced Mohave ground squirrel abundance. However, Glista et al. (2008,
p. 80) found that during a 17-month study in Indiana, only 3 percent of
the animals
[[Page 62250]]
killed on roads were mammals. Garland and Bradley (1984, p. 52) found
no mortality within their study area during an 11-month study on the
effects of a highway on Mojave Desert rodent populations, including the
round-tailed ground squirrel. Also, Rosa and Bissonette (2008, p. 565)
found that in a desert community in southern Utah, roads (specifically
I-15) did not appear to affect small mammal abundance or diversity near
or away from roads and concluded that the abundance and diversity of
small mammals respond more markedly to habitat quality and complexity
than to the presence of roads. Thus, road mortality does not appear to
affect the abundance of small mammals, such as the Mohave ground
squirrel.
In summary, although direct mortality has likely occurred and will
continue to occur during construction, in high-use OHV areas, during
military operations, and on highways, there is no evidence that
mortality is having an impact on the Mohave ground squirrel or is a
significant threat to the species. Although road mortality has not been
studied for the Mohave ground squirrel, research on other species of
small mammals has not found a relationship between road mortality and
abundance. Therefore, we conclude that direct mortality is not
currently a significant threat to the Mohave ground squirrel, nor do we
anticipate it posing a threat in the future.
Habitat Fragmentation
As discussed in Factor A, urban and rural development, OHV
recreational use, transportation infrastructure, military operations,
energy development, and agriculture may cause or contribute to habitat
fragmentation. Habitat fragmentation is the separation or splitting
apart of previously contiguous, functional habitat components of a
species. Habitat fragmentation can result from direct habitat loss that
leaves the remaining habitat in noncontiguous patches, or from the
alteration of habitat areas that render the altered patches unusable to
a species (i.e., functional habitat loss). Alterations that can result
in functional habitat loss include: disturbances that change a
habitat's successional state or remove one or more habitat functions,
creation of physical barriers that preclude the use of otherwise
suitable areas, and activities that prevent animals from using suitable
habitat patches due to behavioral avoidance. When a habitat patch
becomes isolated, the animal population is also isolated, and gene flow
with other populations is reduced or eliminated. A small, isolated
population may not be as able to survive environmental changes or
stochastic events; may experience changes in gene frequencies due to
genetic drift, diminished genetic diversity, and/or effects due to
inbreeding (i.e., inbreeding depression) (Lande 1995, p. 786); and may
eventually be extirpated. Animals from nearby populations are unable to
re-establish the lost population because the habitat is not accessible.
The effects of fragmentation on a species such as the Mohave ground
squirrel depend on a complex array of factors such as patch size, type
of barrier, distance between populations, and condition of habitat
between patches.
Most urban and rural development in the western Mojave Desert has
occurred in the southernmost portion of the range of the Mohave ground
squirrel. This development has destroyed habitat, leaving patches of
various quality and size of Mohave ground squirrel habitat interspersed
among developed areas. In the southernmost portion of the range,
habitat has been severely fragmented, and we assume that any remaining
small patches of Mohave ground squirrel habitat in the southernmost
portion of the range that are surrounded by large areas of urban
development no longer support Mohave ground squirrels. However, none of
the eight important population areas is located in the southernmost
portion of the range, and all eight are at least in part interconnected
by Federal land, where urban development is heavily restricted. Also,
urbanization outside the southernmost portion of the range is limited
to only a few areas and is not a major barrier.
Vehicular recreation, specifically in OHV management and high-use
areas, may cause fragmentation. As mentioned in Factor A, impacts in
OHV areas include disturbance of soils and destruction of shrubs, both
of which combine to reduce the number of native spring annual plants,
which in turn reduces habitat suitability for the Mohave ground
squirrel. We presume these areas are extensively degraded and provide
little value to supporting populations of Mohave ground squirrels now,
or in the future. However, some habitat remains within these areas as
indicated by the occurrence of Mohave ground squirrels in the Dove
Springs Open Area. The distance between squirrel populations, the
distance between habitat patches that may support squirrels, and the
condition of the area between patches are likely primary influences on
the ability of squirrels to move through an OHV management area.
Therefore, the larger management areas (e.g., Spangler Hills) are more
likely to be major barriers than the smaller ones (e.g., Dove Springs).
Regardless, there are relatively few intensively used OHV areas within
the range of the Mohave ground squirrel, and with the possible
exception of Spangler Hills, they do not limit movement between the
eight important population areas (maps 1 and 2). Spangler Hills, the
largest management area, lies between two of the important population
areas and likely limits movement between them. However, these two
population areas, as well as others, remain connected to the west and
south by BLM lands that are closed to cross-country OHV use, including
a portion of the MGSCA, and to the east by a combination of BLM and
NAWS lands. Therefore, we conclude that OHV use does not constitute a
major barrier to Mohave ground squirrel movement.
Transportation infrastructure may cause or contribute to habitat
fragmentation when linear developments (roads) or transportation
corridors substantially reduce or prevent the movement of a species
from one location to another. Negative effects of corridors include
mortality of animals along roadways (Rosen and Lowe 1994, as cited in
Lovich and Bainbridge 1998, p. 331; Boarman and Sazaki 1996, as cited
in Lovich and Bainbridge 1998, p. 331) and restriction of movements and
gene flow (Nicholson 1978, as cited in Lovich and Bainbridge 1999, p.
313).
Radio-collared Mohave ground squirrels are known to have crossed
four-lane, divided highways (Leitner pers. comm., as cited in Defenders
of Wildlife and Stewart 2005, p. 22). However, highways with high
traffic volume and multiple lanes (e.g., I-15 and SR-14) (see Map 1)
may reduce movements of Mohave ground squirrels from one side to the
other. Some stretches of multi-lane highways (I-15 and portions of SR-
14) that cross areas within the range of the Mohave ground squirrel
have, on average, over 36,000 vehicles pass over them daily, while
other multi-lane highways (rural parts of SR-14) and the smaller, two-
lane highways within the species' range have roughly 3,100 to 7,800
vehicles per day, on average (Caltrans 2010c, pp. 33-34, 36-37). We
assume that the increased level of vehicle traffic on the portions of
the multi-lane highways, along with the greater number of physical
hindrances that may result from multiple lanes, is more likely to serve
as a barrier than the smaller, less-traveled two-lane highways. In
these cases, squirrels may be limited to crossing under bridges and
culverts.
[[Page 62251]]
Depending on how roads are constructed, they may serve as physical
hindrances to the movement of Mohave ground squirrels. For example, a
road with a roadway divider (e.g., K-rail) may contribute to making a
roadway a physically impassible barrier for Mohave ground squirrels.
Although there are no studies on the impacts of roads specific to the
Mohave ground squirrel, studies on other small mammals, including other
species of squirrels in desert habitat, have found the following: roads
may have a neutral or slightly positive effect on small mammals
species; roads do not appear to affect small mammal abundance or
diversity near or away from them; and the abundance and diversity of
small mammals responds more markedly to habitat quality and complexity
than to the presence of roads (Rosa and Bissonette 2007, p. 565). In
addition, bridges and culverts, especially those with larger-sized
openings, may allow Mohave ground squirrels to cross under roads
(Painter and Ingraldi 2007, p. 17). Although it is not known whether
the openings under such structures are used regularly by the Mohave
ground squirrel, it is likely that undercrossings with natural
substrates created by larger culverts and bridges are used to some
extent.
Although the amount of contact needed to maintain population
connectivity of Mohave ground squirrels is not known, Mills and
Allendorf (1996, p. 1517) suggested that if 1 to 10 individuals per
generation successfully cross, that level of movement is likely
sufficient to maintain the connection between populations, provided the
overall population is of sufficient size. Thus, a potential barrier
would have to almost entirely eliminate Mohave ground squirrel movement
throughout its length and at all times for it to be a complete barrier.
In addition, Bell et al. (2006, pp. 18, 39, and 40) found low genetic
diversity throughout the range of the species, suggesting that gene
flow occurs throughout the range and roads are not complete barriers to
Mohave ground squirrel movement.
Military operations, such as intense ground forces training
activities on the NTC portion of Fort Irwin, may contribute to
fragmentation of Mohave ground squirrel habitat. The recent expansion
at Fort Irwin will bring the impacts of ground forces training
activities into part of the Coolgardie Mesa-Superior Valley important
population area identified by Leitner (2008, p. 1) (see Factor A,
``Military Operations''). Ground forces training in the expansion area
may restrict Mohave ground squirrel populations to the south from
accessing populations in the Goldstone Complex (see Map 1), thus
isolating the Goldstone area (Defenders of Wildlife and Stewart 2005,
p. 21). However, access for Mohave ground squirrels between the
Goldstone Complex and other areas is available to the west and north
through NAWS. Access from Coolgardie Mesa and Superior Valley to the
west and south is available through the Superior-Cronese DWMA and NAWS
(see Map 2). Although ground forces training will impact part of the
Coolgardie Mesa-Superior Valley important population area, access to
this area from the north, west, and south would not be disrupted by
ground forces training.
Several renewable energy projects have been constructed in the
range of the Mohave ground squirrel; these projects encompass about 2.2
percent of the squirrel's range. Additional renewable energy projects
have been proposed in the western Mojave Desert, and depending on their
size and location, they could reduce the ability of the Mohave ground
squirrel to move between populations.
We know that future renewable energy projects on Federal lands,
which make up about two-thirds of the range of the Mohave ground
squirrel, are likely to be limited. Renewable energy projects proposed
on DOD lands make up less than 0.01 percent of the range of the Mohave
ground squirrel. The BLM has received applications that, if all were
built, would encompass an additional 2.5 percent of the range of the
Mohave ground squirrel. However, this is an overestimate because many
of these proposals overlap and many would be constructed in areas that
are not suitable habitat for squirrels. Also, energy development within
the DWMAs or the MGSCA would be extremely limited because of the 1
percent cap on development and the 5:1 mitigation ratio. The mitigation
in these areas and the 1:1 mitigation the BLM requires outside of these
areas means that, although Mohave ground squirrel habitat may be lost,
habitat would be acquired to add to the large blocks of habitat for the
squirrel in the DWMAs and MGSCA or enhanced to increase the habitat
value of the DWMAs and MGSCA. In addition, solar projects on BLM land
may be more likely to occur in one of the four proposed SEZs, which are
all outside the range of the squirrel. Most of the current and proposed
wind energy projects are located along the western edge of the range of
the Mohave ground squirrel, and many will be situated on ridges and
hilltops, which are not the preferred habitat of the squirrel.
Geothermal energy is available in only two areas within the range of
the squirrel, and few new geothermal projects have been proposed. Thus,
with only a few renewable energy proposals on DOD land and limited
development in the MGSCA and DWMAs, connectivity will not be
significantly degraded.
On non-Federal land, which comprises about one-third of the range
of the Mohave ground squirrel, several solar and wind energy projects
have been proposed that would encompass about 1.2 percent of the range
of the squirrel. However, many of these projects are on lands
previously converted to agriculture or are along the western edge of
the Mohave ground squirrel's range on ridges and hilltops, which is not
preferred habitat. Based on the best scientific and commercial
information available on current management designations, development
limitations, and required mitigation, we conclude that fragmentation of
Mohave ground squirrel habitat is not likely to occur from energy
development.
Agricultural development in the western Mojave Desert is
concentrated in the western Antelope Valley, on the north side of the
San Gabriel Mountains, and from the Mojave River Valley to the Lucerne
Valley. New agricultural development is limited by the availability and
cost of water to produce crops. We recognize that past agricultural
development may have contributed to fragmentation of Mohave ground
squirrel habitat (see Factor A, ``Agriculture'') and that agriculture
in combination with other activities fragmented the habitat of the
Mohave ground squirrel in the Mojave River and Lucerne Valleys.
However, we do not believe that agriculture constitutes an absolute
barrier to squirrel movement because habitat requirements for
dispersing or moving through an area are likely very different than for
those needed for long-term occupancy. Mohave ground squirrels are known
to forage along the edges of alfalfa fields (Hoyt 1972, p. 10) and are
therefore likely able to disperse through such fields.
The BLM and DOD have taken actions to reduce the impact of habitat
fragmentation on Mohave ground squirrels on Federal lands. The BLM
recently designated the MGSCA as a WHMA, two DWMAs as ACECs, and
expanded the size of the DTNA, all of which are within the range of the
Mohave ground squirrel (see Map 2). The DOD bases have ``off-limits''
areas in Mohave ground squirrel habitat, which reduce or eliminate
ground disturbance from military activities. Under the Sikes Act, the
DOD bases are
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obligated to develop cooperative management plans that reflect the
mutual agreement of the CDFG ``concerning conservation, protection, and
management of fish and wildlife resources,'' which includes the Mohave
ground squirrel (see Factor D). The locations of these designated and
``off-limits'' areas form a contiguous area from the northern portion
of the range of the Mohave ground squirrel to the southern portion. The
MGSCA is contiguous with the NAWS and the Fremont-Kramer DWMA, which
connects with the DTNA, EAFB, the Superior-Cronese DWMA, and the
Goldstone Complex (BLM et al. 2005, Map 2-1) (see Map 2). Therefore, at
a landscape scale, the major Federal land management agencies have
identified large, contiguous blocks of habitat from the northern to the
southern portion of the range with management prescriptions to help
conserve the Mohave ground squirrel (see Map 2 and Table 1).
On private lands, we have no information about any landscape-scale
plan that considers the Mohave ground squirrel (e.g., NCCP Plan).
Absent such a plan, private lands within the range of the Mohave ground
squirrel will likely continue to be developed on a case-by-case basis
in the future. Most of the development will likely occur near existing
urban areas in the southernmost portion of the range of the Mohave
ground squirrel, an area which has already been heavily fragmented.
However, none of the eight important population areas are located in
the southernmost portion of the range, and all eight are at least in
part interconnected by Federal land, where development is limited.
Urbanization outside the southernmost portion of the range is limited
to only a few areas and is not a major barrier.
Future development on BLM lands is directed by the WEMO Plan, which
limits development within the MGSCA and the DWMAs to 1 percent. The
three DOD bases have not identified plans to increase their boundaries
for future military missions. Rather, the DOD recently identified a
growing conflict between implementing their military missions and
incompatible residential/commercial development adjacent to their
boundaries. These areas are within the range of the Mohave ground
squirrel and most include native desert plant communities used by
Mohave ground squirrels. Because much of the land on the DOD bases is
not developed and not expected to be developed in the future, and the
military installations' INRMPs have provisions to manage for Mohave
ground squirrel habitat, establishing land buffers will help connect
the Mohave ground squirrel habitat on the military installations with
the DWMAs and MGSCA and increase the area being managed, in part, for
the Mohave ground squirrel. This activity is another means of ensuring
connectivity among the northern, central, and southern portions of the
range of the Mohave ground squirrel and reducing the likelihood of
fragmentation in the future.
In summary, severe fragmentation as a result of urban and rural
development has occurred in the southernmost portion of the Mohave
ground squirrel's range, and movement of the species in that area is
greatly diminished or has been eliminated. However, urban and rural
development in the rest of the range has occurred in only a few areas
and has been more limited in extent. Other activities that may result
in habitat fragmentation (e.g., OHV recreational use, transportation
infrastructure, military operations, and energy development) affect
smaller areas within the range of the Mohave ground squirrel and do not
constitute major barriers to movement, especially between the eight
important population areas, all of which are at least in part
interconnected by Federal land where development that would be a
barrier to movement is not likely to occur. The ability of squirrels to
move between populations is further indicated by recent genetic
research that found low genetic diversity throughout the range of the
species, which could suggest that gene flow occurs throughout the range
(Bell et al. 2006, pp. 18, 39, 40). We therefore conclude that habitat
fragmentation is currently not a threat to the Mohave ground squirrel,
nor do we anticipate it posing a threat in the future.
Summary of Factor E
Although direct mortality has likely occurred and will continue to
occur during construction, in high-use OHV areas, during military
operations, and on highways, there is no evidence that mortality is
having an impact on the Mohave ground squirrel or is a significant
threat to the species. Although road mortality has not been studied for
the Mohave ground squirrel, research on other species of small mammals
has not found a relationship between road mortality and abundance.
Severe habitat fragmentation as a result of urban and rural
development has occurred in the southernmost portion of the range of
the Mohave ground squirrel and will likely continue to occur in that
area. However, large, contiguous tracts of Federal land occur
throughout the rest of the range of the Mohave ground squirrel, which
will largely remain undeveloped. These lands support key Mohave ground
squirrel population areas, including the eight important population
areas, and provide connectivity throughout much of the range of the
Mohave ground squirrel, both among these important population areas and
from the northern portion through the central and southern portions of
the squirrel's range. This connectivity helps ensure exchange of
genetic material among the populations of Mohave ground squirrels and
prevents the deleterious effects of small population dynamics such as
inbreeding depression. Renewable energy projects are proposed for BLM
land, but these will likely be very limited in the MGSCA and DWMAs in
which development of all types is limited to 1 percent of the areas.
Much of the range of the Mohave ground squirrel has not been developed,
is not proposed for development at this time, or cannot be developed
because of restrictions imposed by the BLM and DOD.
Therefore, based on our review of the best available scientific and
commercial information, we conclude that the Mohave ground squirrel is
not currently threatened by other natural or manmade factors throughout
its range, nor do we anticipate other natural or manmade factors posing
a threat in the future.
Finding
As required by the Act, we considered the five factors in assessing
whether the Mohave ground squirrel is threatened or endangered
throughout all or a significant portion of its range. We have assessed
the best scientific and commercial information available regarding
threats faced by the Mohave ground squirrel. We have reviewed the
petition, scientific literature, information available in our files,
and all information submitted to us following our 90-day petition
finding (75 FR 22063, April 27, 2010). We also consulted with
recognized Mohave ground squirrel experts, Federal and State land
managers, and local governments to assess potential threats to the
habitat and range of the species relative to current and planned land
uses and occurrences of the species.
We analyzed the potential threats to the Mohave ground squirrel
including: Habitat loss and habitat degradation from urban and rural
development, OHV recreational use, transportation infrastructure,
military operations, energy development, livestock grazing,
agriculture, mining, and climate change; predation by native species
and
[[Page 62253]]
domestic dogs and cats; the inadequacy of regulatory mechanisms to
control land use and development on private, State, and Federal lands;
direct mortality; and habitat fragmentation. We found that the Mohave
ground squirrel continues to be present throughout a large portion of
its historical and current range.
Land ownership within the range of the Mohave ground squirrel is
about one-third private land, one-third DOD land, and one-third BLM
land. While much of the private land in the southernmost portion of the
range of the Mohave ground squirrel has been developed or used for
agriculture, little of the squirrel's range has been developed in the
central and northern portions of its range where most is under Federal
jurisdiction and is not subject to development.
Sources of threats on non-Federal lands include urban and rural
development, transportation infrastructure, renewable energy,
agriculture, and mining. We estimate that current and future
development will comprise about 9-10 percent of the range of the Mohave
ground squirrel, with most occurring in the incorporated areas.
Although there is no information specific to the Mohave ground
squirrel, roads are known in some cases to affect species and their
habitat beyond the loss of habitat from construction of the road
itself. As a worst case, we calculated a road-effect zone of about 0.7
percent of the range for the construction of a new major highway and
the expansion of two existing major highways. However, research
indicates that the effects of roads on small mammals in the desert are
neutral to slightly positive; thus, there may be no negative road-
effect zone for the Mohave ground squirrel. Several renewable energy
projects have been proposed on private land, which would encompass
about 1.2 percent of the Mohave ground squirrel's range, but many of
these are proposed for land that has already been converted to
agriculture. Although we estimate that about 1 percent of the range of
the Mohave ground squirrel has been converted to agriculture, because
of increasing costs for water and economic incentives to use this land
for other purposes, agricultural lands are being converted to urban or
rural development. There are few large mines on private land in the
range of the Mohave ground squirrel.
On military lands, the impacts to the Mohave ground squirrel are
mainly from the training of ground forces at the NTC along the eastern
portion of the species' range. EAFB and NAWS conduct aircraft and
weapons testing, which leaves most of the area and habitat on these two
large bases ``off limits'' to ground forces operations. The Goldstone
Complex is also off limits to such operations. There is limited
development at the small cantonment area at each military base, OHV use
is restricted to designated areas that total about 0.2 percent of the
range of the Mohave ground squirrel, and two military bases have
announced plans to construct renewable energy projects that could
impact about 0.3 percent of the range of the Mohave ground squirrel.
Mining is prohibited on military land.
Recently, the BLM has undertaken several conservation measures
specific to the Mohave ground squirrel and its habitat or measures that
benefit the species on its lands. The BLM designated the Fremont-Kramer
and Superior-Cronese DWMAs as ACECs, increased the size of the DTNA and
Rand ACEC, and established the MGSCA. These designations place
additional restrictions on land use and require the BLM to manage these
lands in part for Mohave ground squirrel habitat. One such restriction
is a 1 percent cap on total new development within the MGSCA and DWMAs
under the WEMO Plan with the requirement for 5:1 mitigation. On BLM
land, cross-country OHV use is limited to a few specific areas, and the
number of open roads and trails within the range of the Mohave ground
squirrel has been reduced. The BLM is restoring habitat in areas with
closed routes, signing open and closed routes, increasing enforcement
of route designations, and implementing a monitoring plan to determine
compliance with route closures and to identify whether any new illegal
routes are being created. Future energy development is restricted or
limited in its location and areal extent in much of the range of the
Mohave ground squirrel. The BLM's 1 percent cap on total new
development within the MGSCA and DWMAs, including energy projects,
limits the impacts of proposed or future projects in much of the range
of the Mohave ground squirrel.
Livestock grazing on BLM land has been reduced with the BLM's
recent implementation of public land health standards and guidelines
for grazing. The BLM has implemented a 33 percent reduction in the area
authorized for grazing in the range of the Mohave ground squirrel,
eliminated ephemeral grazing for cattle in the DWMAs, eliminated sheep
grazing in most of the DWMAs, excluded cattle grazing in the spring in
DWMAs in years when annual plant productivity is low, excluded cattle
grazing on NAWS, and authorized the ability of permittees to
voluntarily relinquish cattle and sheep allotments. Over time, these
changes are likely to provide increased foraging opportunities for the
Mohave ground squirrel and reduce the overall amount of time that
livestock spend within these areas, thus reducing impacts to soils,
vegetation, and dietary overlap.
Potential threats associated with climate change are a concern, but
we do not have evidence to conclude that the threats rise to the level
of potentially threatening the Mohave ground squirrel within the
foreseeable future.
Overall, we estimate that in the next 20-30 years about one-third
of the range of the Mohave ground squirrel could potentially be lost.
However, because of a general lack of information on the species and
uncertainty over future development we based this estimate on a series
of worst-case assumptions (e.g., we double-counted impacts, assumed
impacts existed or were worse than the available information indicated,
assumed all habitat within a project boundary would be lost), and we
expect that the actual loss during this timeframe will be much less. In
addition, we did not include the mitigation for the Mohave ground
squirrel that would be implemented for project implementation. Even if
the worst case occurs, we expect that most of the remaining area will
remain relatively undisturbed and in the same condition as it is today.
More than 80 percent of the remaining land is Federal, much of which
(e.g., EAFB, NAWS, Goldstone Complex, DWMAs, and MGSCA) is managed, at
least in part, for the Mohave ground squirrel and its habitat. Of
particular importance to the status of the Mohave ground squirrel, much
of the remaining lands are contiguous and provide connectivity from the
northern end of the range to well south of SR-58 in the southern
portion of the range. More importantly, these lands contain most or all
the habitat within the eight important population areas and include
habitat that provides for connectivity among the eight areas.
Therefore, we conclude that the present or threatened destruction,
modification, or curtailment of the habitat or range of the Mohave
ground squirrel is not a significant threat to this species now or in
the foreseeable future.
We found no information that over-collection or overutilization for
commercial, recreational, scientific, or educational purposes is a
threat or will become a threat to the species in the future. Therefore,
we conclude that overutilization for commercial, recreational,
scientific, or educational purposes does not threaten the Mohave
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ground squirrel now or in the foreseeable future.
We also found no evidence suggesting that disease is affecting the
Mohave ground squirrel, and therefore, conclude that disease does not
threaten the Mohave ground squirrel. Similarly, we found no information
suggesting that predation by domestic dogs or cats is affecting the
Mohave ground squirrel. Information on the rate of predation by a
native predator (coyote) was inferred in one study, but it did not show
this rate to be a threat to the Mohave ground squirrel. Although the
number of common ravens in the western Mojave Desert has increased
substantially in the past few decades, we found no information
suggesting that predation by the common raven on the Mohave ground
squirrel has increased or is adversely affecting the squirrel.
Therefore, we conclude that disease or predation are not significant
threats to the Mohave ground squirrel now or in the foreseeable future.
The Mohave ground squirrel is listed as threatened by the State of
California under the CESA. There are other regulatory mechanisms in
place, such as CEQA, FLPMA, and Sikes Act that, when implemented,
provide protections from threats to the Mohave ground squirrel on
Federal, State, and private land. On Federal lands, agencies such as
the BLM and DOD have implemented actions under these laws that provide
for the conservation of the Mohave ground squirrel on much of the lands
that they manage. We conclude the inadequacy of regulatory mechanisms
is not a significant threat to the Mohave ground squirrel now or in the
foreseeable future.
We considered direct mortality as a potential threat, and although
direct mortality has likely occurred and will continue to occur during
construction, in high-use OHV areas, during military operations, and on
roads, there is no evidence that mortality is having an impact on the
Mohave ground squirrel or is a significant threat to the species.
Although road mortality has not been studied for the Mohave ground
squirrel, research on other species of small mammals has not found a
relationship between road mortality and abundance.
Severe habitat fragmentation as a result of urban and rural
development has occurred in the southernmost portion of the range of
the Mohave ground squirrel and will likely continue to occur in that
area. However, large, contiguous tracts of Federal land occur
throughout the rest of the range of the Mohave ground squirrel, which
will largely remain undeveloped. These lands support many Mohave ground
squirrel population areas, including the eight important population
areas, and provide connectivity throughout much of the range of the
Mohave ground squirrel both among these important population areas and
from the northern portion through the central and southern portions of
the squirrel's range. This connectivity helps ensure exchange of
genetic material among the populations of Mohave ground squirrels and
prevents the deleterious effects of small population dynamics such as
inbreeding depression. Renewable energy projects are proposed for BLM
land, but these will likely be very limited in the MGSCA and DWMAs in
which development of all types is limited to 1 percent of the areas.
Much of the range of the Mohave ground squirrel has not been developed,
is not proposed for development at this time, or cannot be developed
because of restrictions imposed by the BLM and DOD. We conclude that
other natural or manmade factors are not significant threats to the
Mohave ground squirrel now or in the foreseeable future.
Our review of the best available scientific and commercial
information pertaining to the five factors, does not support a
conclusion that there are independent or cumulative threats of
sufficient imminence, intensity, or magnitude to indicate that the
Mohave ground squirrel is in danger of extinction (endangered), or
likely to become endangered within the foreseeable future (threatened),
throughout its range. Therefore, listing the Mohave ground squirrel as
endangered or threatened is not warranted at this time.
Distinct Vertebrate Population Segment
After assessing whether the species is endangered or threatened
throughout its range, we next consider whether any distinct vertebrate
populations segment (DPS) exists and meets the definition of endangered
or is likely to become endangered in the foreseeable future
(threatened). Under the Service's Policy Regarding the Recognition of
Distinct Vertebrate Population Segments Under the Endangered Species
Act (61 FR 4722; February 7, 1996), three elements are considered in
the decision concerning the establishment and classification of a
possible DPS. These are applied similarly for additions to or removal
from the Federal List of Endangered and Threatened Wildlife. These
elements include:
(1) The discreteness of a population in relation to the remainder
of the species to which it belongs;
(2) The significance of the population segment to the species to
which it belongs; and
(3) The population segment's conservation status in relation to the
Act's standards for listing, delisting, or reclassification (i.e., is
the population segment endangered or threatened).
Under the DPS Policy, we must first determine whether the
population qualifies as a DPS; this requires a finding that the
population is both: (1) Discrete in relation to the remainder of the
species to which it belongs; and (2) biologically and ecologically
significant to the species to which it belongs. If the population meets
the first two criteria under the DPS policy, we then proceed to the
third element in the process, which is to evaluate the population
segment's conservation status in relation to the Act's standards for
listing as an endangered or threatened species. The DPS evaluation in
this finding concerns the Mohave ground squirrel that we were
petitioned to list as threatened or endangered.
Discreteness
Under the DPS Policy, a population segment of a vertebrate taxon
may be considered discrete if it satisfies either one of the following
conditions:
(1) It is markedly separated from other populations of the same
taxon as a consequence of physical, physiological, ecological, or
behavioral factors. Quantitative measures of genetic or morphological
discontinuity may provide evidence of this separation.
(2) It is delimited by international governmental boundaries within
which differences in control of exploitation, management of habitat,
conservation status, or regulatory mechanisms exist that are
significant in light of section 4(a)(1)(D) of the Act.
Markedly Separated From Other Populations of the Taxon
As described previously (see Species Information above), the Mohave
ground squirrel extends throughout the range except where the habitat
has been lost due to human activities, primarily along the southern and
eastern portion of its range. We found no information that any Mohave
ground squirrel population is markedly separated from other populations
as a consequence of physical, physiological, ecological, or behavioral
factors.
There are no international governmental boundaries associated with
this species that are significant. The Mohave ground squirrel is found
wholly within the United States. Because this element is not relevant
in this case for a finding of discreteness, it
[[Page 62255]]
was not considered in reaching the determination.
We did not find any information that would indicate any DPS exists.
Therefore, we determine, based on a review of the best available
information, that there are no portions of the species' range that meet
the discreteness criterion of the Service's DPS policy. The DPS policy
is clear that significance is analyzed only when a population segment
has been identified as discrete. Because both discreteness and
significance are required to satisfy the DPS policy, we have determined
that there are no populations of the Mohave ground squirrel that
qualify as a DPS under our policy. As a result, no further analysis
under the DPS policy is necessary.
Significant Portion of the Range Analysis
Having determined that the Mohave ground squirrel is not in danger
of extinction or likely to become endangered within the foreseeable
future throughout all of its range, we must next consider whether there
are any significant portions of the range where the Mohave ground
squirrel is in danger of extinction or is likely to become endangered
in the foreseeable future.
Decisions by the Ninth Circuit Court of Appeals in Defenders of
Wildlife v. Norton, 258 F.3d 1136 (2001) and Tucson Herpetological
Society v. Salazar, 566 F.3d 870 (2009) found that the Act requires the
Service, in determining whether a species is endangered or threatened
throughout a significant portion of its range, to consider whether lost
historical range of a species (as opposed to its current range)
constitutes a significant portion of the range of that species. While
this is not our interpretation of the statute, we first address the
lost historical range before addressing the current range.
Historical Range
Available information provides no evidence of a significant loss of
the historical range of the Mohave ground squirrel. Although the
petition to list the Mohave ground squirrel indicated that the western
Antelope Valley was no longer part of the species' current range,
suitable habitat still remains in much of the western Antelope Valley
and may be connected to habitat currently occupied by the Mohave ground
squirrel. This information is supported by recent visual observations
of Mohave ground squirrels in the western Antelope Valley (see ``Range
and Distribution'' section). Additionally, although areas of natural
habitat within the range of the Mohave ground squirrel have been lost
or degraded from human activity (see Factor A), the boundary of the
current range is larger than reported by Howell in 1938, and may even
be larger than now defined by the Service, as there have been recent
sightings beyond the area defined by the Service as the range of the
Mohave ground squirrel (see ``Range and Distribution'' section).''
Therefore, there is no lost historical range of the Mohave ground
squirrel that could constitute a significant portion of the range of
the species.
Current Range
The Act defines ``endangered species'' as any species which is ``in
danger of extinction throughout all or a significant portion of its
range,'' and ``threatened species'' as any species which is ``likely to
become an endangered species within the foreseeable future throughout
all or a significant portion of its range.'' The definition of species
is also relevant to this discussion. The Act defines ``species'' as
follows: ``The term `species' includes any subspecies of fish or
wildlife or plants, and any distinct population segment [DPS] of any
species of vertebrate fish or wildlife which interbreeds when mature.''
The phrase ``significant portion of its range'' (SPR) is not defined by
the statute, and we have never addressed in our regulations: (1) The
consequences of a determination that a species is either endangered or
likely to become so throughout a significant portion of its range, but
not throughout all of its range; or (2) what qualifies a portion of a
range as ``significant.''
Two recent district court decisions have addressed whether the SPR
language allows the Service to list or protect less than all members of
a defined ``species'': Defenders of Wildlife v. Salazar, 729 F. Supp.
2d 1207 (D. Mont. 2010), concerning the Service's delisting of the
Northern Rocky Mountain gray wolf (74 FR 15123, Apr. 12, 2009); and
WildEarth Guardians v. Salazar, 2010 U.S. Dist. LEXIS 105253 (D. Ariz.
Sept. 30, 2010), concerning the Service's 2008 finding on a petition to
list the Gunnison's prairie dog (73 FR 6660, Feb. 5, 2008). The Service
had asserted in both of these determinations that it had authority, in
effect, to protect only some members of a ``species,'' as defined by
the Act (i.e., species, subspecies, or DPS), under the Act. Both courts
ruled that the determinations were arbitrary and capricious on the
grounds that this approach violated the plain and unambiguous language
of the Act. The courts concluded that reading the SPR language to allow
protecting only a portion of a species' range is inconsistent with the
Act's definition of ``species.'' The courts concluded that once a
determination is made that a species (i.e., species, subspecies, or
DPS) meets the definition of ``endangered species'' or ``threatened
species,'' it must be placed on the list in its entirety and the Act's
protections applied consistently to all members of that species
(subject to modification of protections through special rules under
sections 4(d) and 10(j) of the Act).
Consistent with that interpretation, and for the purposes of this
finding, we interpret the phrase ``significant portion of its range''
in the Act's definitions of ``endangered species'' and ``threatened
species'' to provide an independent basis for listing: a species may be
endangered or threatened throughout all of its range; or a species may
be endangered or threatened in only a significant portion of its range.
If a species is in danger of extinction throughout an SPR, it, the
species, is an ``endangered species.'' The same analysis applies to
``threatened species.'' Based on this interpretation and supported by
existing case law, the consequence of finding that a species is
endangered or threatened in only a significant portion of its range is
that the entire species shall be listed as endangered or threatened,
respectively, and the Act's protections shall be applied across the
species' entire range.
We conclude, for the purposes of this finding, that interpreting
the SPR phrase as providing an independent basis for listing is the
best interpretation of the Act because it is consistent with the
purposes and the plain meaning of the key definitions of the Act; it
does not conflict with established past agency practice (i.e., prior to
the 2007 Solicitor's Opinion), as no consistent, long-term agency
practice has been established; and it is consistent with the judicial
opinions that have most closely examined this issue. Having concluded
that the phrase ``significant portion of its range'' provides an
independent basis for listing and protecting the entire species, we
next turn to the meaning of ``significant'' to determine the threshold
for when such an independent basis for listing exists.
Although there are potentially many ways to determine whether a
portion of a species' range is ``significant,'' we conclude, for the
purposes of this finding, that the significance of the portion of the
range should be determined based on its biological contribution to the
conservation of the species. For this reason, we describe the threshold
for ``significant'' in terms of an increase in the risk of extinction
for the species. We conclude that a
[[Page 62256]]
biologically based definition of ``significant'' best conforms to the
purposes of the Act, is consistent with judicial interpretations, and
best ensures species' conservation. Thus, for the purposes of this
finding, and as explained further below, a portion of the range of a
species is ``significant'' if its contribution to the viability of the
species is so important that without that portion, the species would be
in danger of extinction.
We evaluate biological significance based on the principles of
conservation biology using the concepts of resiliency, redundancy, and
representation. Resiliency describes the characteristics of a species
and its habitat that allow it to recover from periodic disturbance.
Redundancy (having multiple populations distributed across the
landscape) may be needed to provide a margin of safety for the species
to withstand catastrophic events. Representation (the range of
variation found in a species) ensures that the species' adaptive
capabilities are conserved. Resiliency, redundancy, and representation
are not independent of each other, and some characteristic of a species
or area may contribute to all three. For example, distribution across a
wide variety of habitat types is an indicator of representation, but it
may also indicate a broad geographic distribution contributing to
redundancy (decreasing the chance that any one event affects the entire
species), and the likelihood that some habitat types are less
susceptible to certain threats, contributing to resiliency (the ability
of the species to recover from disturbance). None of these concepts is
intended to be mutually exclusive, and a portion of a species' range
may be determined to be ``significant'' due to its contributions under
any one or more of these concepts.
For the purposes of this finding, we determine if a portion's
biological contribution is so important that the portion qualifies as
``significant'' by asking whether without that portion, the resiliency,
redundancy, or representation of the species would be so impaired that
the species would have an increased vulnerability to threats to the
point that the overall species would be in danger of extinction (i.e.,
would be ``endangered''). Conversely, we would not consider the portion
of the range at issue to be ``significant'' if there is sufficient
resiliency, redundancy, and representation elsewhere in the species'
range that the species would not be in danger of extinction throughout
its range if the population in that portion of the range in question
became extirpated (extinct locally).
We recognize that this definition of ``significant'' (a portion of
the range of a species is ``significant'' if its contribution to the
viability of the species is so important that without that portion, the
species would be in danger of extinction) establishes a threshold that
is relatively high. On the one hand, given that the consequences of
finding a species to be endangered or threatened in an SPR would be
listing the species throughout its entire range, it is important to use
a threshold for ``significant'' that is robust. It would not be
meaningful or appropriate to establish a very low threshold whereby a
portion of the range can be considered ``significant'' even if only a
negligible increase in extinction risk would result from its loss.
Because nearly any portion of a species' range can be said to
contribute some increment to a species' viability, use of such a low
threshold would require us to impose restrictions and expend
conservation resources disproportionately to conservation benefit:
listing would be rangewide, even if only a portion of the range of
minor conservation importance to the species is imperiled. On the other
hand, it would be inappropriate to establish a threshold for
``significant'' that is too high. This would be the case if the
standard were, for example, that a portion of the range can be
considered ``significant'' only if threats in that portion result in
the entire species' being currently endangered or threatened. Such a
high bar would not give the SPR phrase independent meaning, as the
Ninth Circuit held in Defenders of Wildlife v. Norton, 258 F.3d 1136
(9th Cir. 2001).
The definition of ``significant'' used in this finding carefully
balances these concerns. By setting a relatively high threshold, we
minimize the degree to which restrictions will be imposed or resources
expended that do not contribute substantially to species conservation.
But we have not set the threshold so high that the phrase ``in a
significant portion of its range'' loses independent meaning.
Specifically, we have not set the threshold as high as it was under the
interpretation presented by the Service in the Defenders litigation.
Under that interpretation, the portion of the range would have to be so
important that current imperilment there would mean that the species
would be currently imperiled everywhere. Under the definition of
``significant'' used in this finding, the portion of the range need not
rise to such an exceptionally high level of biological significance.
(We recognize that if the species is imperiled in a portion that rises
to that level of biological significance, then we should conclude that
the species is in fact imperiled throughout all of its range, and that
we would not need to rely on the SPR language for such a listing.)
Rather, under this interpretation we ask whether the species would be
endangered everywhere without that portion, i.e., if that portion were
completely extirpated. In other words, the portion of the range need
not be so important that even the species being in danger of extinction
in that portion would be sufficient to cause the species in the
remainder of the range to be endangered; rather, the complete
extirpation (in a hypothetical future) of the species in that portion
would be required to cause the species in the remainder of the range to
be endangered.
The range of a species can theoretically be divided into portions
in an infinite number of ways. However, there is no purpose to
analyzing portions of the range that have no reasonable potential to be
significant or to analyzing portions of the range in which there is no
reasonable potential for the species to be endangered or threatened. To
identify only those portions that warrant further consideration, we
determine whether there is substantial information indicating that: (1)
The portions may be ``significant,'' and (2) the species may be in
danger of extinction there or likely to become so within the
foreseeable future. Depending on the biology of the species, its range,
and the threats it faces, it might be more efficient for us to address
the significance question first or the status question first. Thus, if
we determine that a portion of the range is not ``significant,'' we do
not need to determine whether the species is endangered or threatened
there; if we determine that the species is not endangered or threatened
in a portion of its range, we do not need to determine if that portion
is ``significant.'' In practice, a key part of the determination that a
species is in danger of extinction in a significant portion of its
range is whether the threats are geographically concentrated in some
way. If the threats to the species are essentially uniform throughout
its range, no portion is likely to warrant further consideration.
Moreover, if any concentration of threats to the species occurs only in
portions of the species' range that clearly would not meet the
biologically based definition of ``significant,'' such portions will
not warrant further consideration.
Through our range-wide analysis, we found that there is not one
individual
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impact that occurs throughout the range of the species, that is, the
threats are not uniform throughout the species' range, and that some
areas receive a greater number of impacts, although the magnitude may
vary. After reviewing the potential threats throughout the range of the
Mohave ground squirrel, we determine that there may be two portions of
the squirrel's range that could be considered to have concentrated
threats for the species there: one area is in the southern portion of
the range and the other is the central portion of the range where Fort
Irwin is located. Impacts in the southern portion of the species' range
include urban and rural development, recreation, transportation
network, military operations, energy development, livestock grazing,
agriculture, and mining. In the central portion, the impacts include
urban and rural development, OHV recreational use, military operations,
energy development, livestock grazing, and mining. Below, we outline
the elevated threats found in these portions. We then assess whether
these portions of the species' range may meet the biologically based
definition of ``significant,'' that is, whether the contributions of
these portions of the Mohave ground squirrel's range to the viability
of the species is so important that without those portions, the species
would be in danger of extinction.
Southern Portion of the Range: The impacts of urban and rural
development and agriculture are concentrated in the southern portion of
the range of the Mohave ground squirrel. This area is south of the
Fremont-Kramer DWMA, south of EAFB, and south of SR-138 (see Maps 1 and
2). This area is the location of much of the urban and rural
development and agriculture in the western Mojave Desert. Much of the
western portion of the Antelope Valley south of SR-138, the area south
of Littlerock and Pearblossom, and the Mojave River Valley have been
developed for intensive agriculture (USGS 2000. p. 1). In addition,
most of the human population in the western Mojave Desert is located in
this area. As mentioned in the ``Urban and Rural Development'' section,
about 300,000 ac (121,406 ha) south of SR-58, which is about 5.6
percent of the range of the Mohave ground squirrel, is incorporated
(BLM 2005a, p. 3-2) and subject to future development. Additional
acreage has been affected by rural development along the southern
portion of the range of the Mohave ground squirrel, but data on this
area are unavailable. More than 39,000 ac (15,700 ha) has been lost to
agriculture including the Antelope Valley and Mojave River Basin
(Gustafson 1993, p. 24). The known losses in urban and rural
development and agriculture are about 6.4 percent of the range of the
Mohave ground squirrel, but the actual losses would be larger when
including the unincorporated areas of development. This urban and rural
development and agriculture are mostly located along the southern edge
of the range of the Mohave ground squirrel (Map 2). Their locations
would not inhibit the movement of the Mohave ground squirrel among the
important population areas.
Central Portion of the Range: The second area where impacts are
concentrated is the Fort Irwin NTC, including the expansion area. The
area is about 435,978 ac (176,435 ha) including the expansion area, or
about 8.2 percent of the range of the Mohave ground squirrel. However,
not all of this area is used for ground forces training so the area of
impact is less. One of the Mohave ground squirrel important population
areas, the Coolgardie Mesa-Superior Valley core area, is located on
lands managed by the BLM and Fort Irwin (expansion area and Goldstone
Complex). Although part of this important population area will be
subject to ground forces training, part is an off-limits area to these
impacts (Charis 2005, chapter 4, p. 14), part is located on lands
managed by the BLM that include an ACEC for the federally endangered
Lane Mountain milk-vetch (Astragalus jaegerianus), and the desert
tortoise (BLM et al. 2005, chapter 2, pp. 15, 214-215), and part is in
the Goldstone Complex which is off-limits to military training. The
Army has designated areas within the expansion area that combined total
6,704 ac (2,713 ha) as off-limits ground forces training (Charis 2005,
chapter 4, pp. 11, 21, 22).
For this analysis, we will look at the significance question first
(i.e., whether the concentration of these threats applies to portions
of the range that are so important to the viability of the species that
without those portions, the species would be in danger of extinction).
To do so, we conduct an evaluation of resiliency, redundancy, and
representation. The terms ``resiliency,'' ``redundancy,'' and
``representation'' are intended to be indicators of the conservation
value of portions of the range.
Resiliency of a species allows the species to recover from periodic
disturbance. A species will likely be more resilient if large
populations exist in high-quality habitat that is distributed
throughout the range of the species in such a way as to capture the
environmental variability found within the range of the species. A
portion of the range of a species may make an essential contribution to
the resiliency of the species if the area is relatively large and
contains particularly high-quality habitat, or if its location or
characteristics make it less susceptible to certain threats than other
portions of the range. When evaluating whether or how a portion of the
range contributes to resiliency of the species, we evaluate the
historical value of the portion and how frequently the portion is used
by the species, if possible. In addition, the portion may contribute to
resiliency for other reasons--for instance, it may contain an important
concentration of certain types of habitat that are necessary for the
species to carry out its life-history functions, such as breeding,
feeding, migration, dispersal, or wintering.
Resiliency, as a measure of a portion of the range's contribution
to the viability of the species, may apply if a portion occurs in an
environment that is meaningfully different from the rest; that is,
representing differences to capture the environmental variability
within the range of the species. We found that there was a large,
contiguous area with management guidance for the Mohave ground squirrel
(e.g. the MGSCA, NAWS, Fremont-Kramer DWMA and DTNA, Superior-Cronese
DWMA, Goldstone Complex, and EAFB) (see Map 2). This area occurs from
the northern portion through the southern portion of the species'
range, and represents a variety of latitudes, elevations, rainfall,
temperatures, soils, and vegetation. Based on a review of the best
available scientific and commercial information, we find no indication
that any geographic area is different from the rest of the range of the
Mohave ground squirrel regarding environmental variability, or that one
portion of the Mohave ground squirrel's range exhibits ecological or
environmental characteristics that differ from another portion.
Therefore, we conclude that the Southern and the Central portions of
the range of the Mohave ground squirrel, individually and in
combination, do not provide an essential contribution to the resiliency
of the species.
Redundancy of populations may be needed to provide a margin of
safety for the species to withstand catastrophic events. This does not
mean that any portion that provides redundancy is necessarily a
significant portion of the range of a species. The idea is to conserve
enough areas of the range such that random perturbations in the system
act on only a few populations.
[[Page 62258]]
Therefore, each area must be examined based on whether that area
provides an increment of redundancy that is important to the
conservation of the species.
Redundancy is a measure to ensure that a species is able to
withstand catastrophic events. If sufficiently large enough areas of
the species are conserved, then random events would impact only a small
portion of the species. Researchers have identified eight important
population areas where Mohave ground squirrels are known to occur
consistently (Leitner 2008, pp. 10-12). Mohave ground squirrels are
also known to occur in many other areas, although less is known about
those populations. These important areas occur throughout much of the
range of the Mohave ground squirrel including the southern, central,
and northern portions of the species' range. There may be more
important population areas for the Mohave ground squirrel that have not
been identified because much of the range of the species has not been
surveyed to determine population location and trend. Based on the best
available scientific and commercial information, we find that there is
a large area being managed for the species (see Map 2) and that the
eight important population areas and other potentially important
population areas are well distributed across the species' range. Thus,
there is no portion of the range of the Mohave ground squirrel
identified as being necessary to conserve the species in case there is
a catastrophic event. Therefore, we conclude that the Southern and the
Central portions of the range of the Mohave ground squirrel,
individually and in combination, do not provide an essential
contribution to the redundancy of the species.
Adequate representation ensures that the species' adaptive
capabilities are conserved. Specifically, the portion should be
evaluated to see how it contributes to the genetic diversity of the
species. The loss of genetically based diversity may substantially
reduce the ability of the species to respond and adapt to future
environmental changes. A peripheral population may provide an essential
contribution to representation if there is evidence that it provides
genetic diversity due to its location on the margin of the species'
habitat requirements.
Representation includes the genetic diversity of the species. We
found that, using mitochondrial DNA (a maternally inherited genetic
marker), estimates of gene flow among the past few generations were low
between some populations (Coolgardie Mesa and EAFB) but not others
(Olancha and Freeman Gulch, Freeman Gulch and EAFB) (Bell 2006, pp. 42-
44). This reduced gene flow may have been caused by the recent drought
years in the western Mojave Desert or limited movements of female
Mohave ground squirrels. However, when using nuclear DNA, which is
inherited from both parents rather than just the mother, the results
did not show that gene flow was low between populations of Mohave
ground squirrels. Bell's genetic analysis of long-term levels of gene
flow among Mohave ground squirrel populations found low levels of
subdivision among Mohave ground squirrel populations including between
Coolgardie Mesa and EAFB (Bell 2006, pp. 43, 72), indicating that gene
flow among Mohave ground squirrel populations including from the
Coolgardie Mesa population west to EAFB has occurred over the long
term. In addition, we did not find any information that indicates the
population in the southern portion, where impacts are concentrated,
provides genetic diversity to the species as a whole. Bell (2006, pp.
18, 39, 40) found low genetic diversity throughout the range of the
species, indicating that gene flow occurs throughout the range.
Therefore, we conclude that the Southern and the Central portions of
the range of the Mohave ground squirrel, individually and in
combination, do not provide an essential contribution to the
representation of the species.
Based on the discussion above, we have determined that the Mohave
ground squirrel does not face elevated threats in most portions of its
range, and that those portions of the Mohave ground squirrel's range
that may have concentrated threats (the Southern and the Central
portions of the range) do not contribute to the resiliency, redundancy,
and representation of the Mohave ground squirrel such that without
these portions, the species would be in danger of extinction.
Accordingly, we find that the Mohave ground squirrel is not endangered
or threatened in a significant portion of its range.
We do not find that the Mohave ground squirrel is in danger of
extinction now, nor is it likely to become endangered within the
foreseeable future throughout all or a significant portion of its
range. Therefore, listing the Mohave ground squirrel as endangered or
threatened under the Act is not warranted at this time.
We request that you submit any new information concerning the
status of, or threats to, the Mohave ground squirrel to our Ventura
Fish and Wildlife Office (see ADDRESSES section) whenever it becomes
available. New information will help us monitor this species and
encourage its conservation. If an emergency develops for this or any
other species, we will act to provide immediate protection.
References Cited
A complete list of references cited is available on the Internet at
http://www.regulations.gov and upon request from the Ventura Fish and
Wildlife Office (see ADDRESSES section).
Author
The primary authors of this notice are staff members of the Ventura
Fish and Wildlife Office (see ADDRESSES section).
Authority: The authority for this action is section 4 of the
Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).
Dated: September 23, 2011.
Gregory E. Siekaniec,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 2011-25473 Filed 10-5-11; 8:45 am]
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