Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To Remove the Stephens' Kangaroo Rat From the Federal List of Endangered and Threatened Wildlife, 51204-51223 [2010-20518]
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Federal Register / Vol. 75, No. 160 / Thursday, August 19, 2010 / Proposed Rules
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Dana A. Goward,
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BILLING CODE 9110–04–P
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS–R8–ES–2010–0052;
92220–1113–0000C5]
Endangered and Threatened Wildlife
and Plants; 12-Month Finding on a
Petition To Remove the Stephens’
Kangaroo Rat From the Federal List of
Endangered and Threatened Wildlife
Fish and Wildlife Service,
Interior.
ACTION: Notice of 12-month petition
finding.
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AGENCY:
We, the U.S. Fish and
Wildlife Service (Service), announce a
12-month finding on a petition to
remove the Stephens’ kangaroo rat
(Dipodomys stephensi) from the Federal
List of Endangered and Threatened
SUMMARY:
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Wildlife under the Endangered Species
Act of 1973, as amended. After a review
of the best available scientific and
commercial information, we find that
delisting the Stephens’ kangaroo rat is
not warranted at this time. However, we
ask the public to submit to us any new
information that becomes available
concerning the threats to the Stephens’
kangaroo rat or its habitat at any time.
This information will help us monitor
and encourage the conservation of this
species.
DATES: The finding announced in this
document was made on August 19,
2010.
ADDRESSES: This finding is available on
the Internet at https://
www.regulations.gov at Docket Number
FWS–R8–ES–2010–0052. 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, Carlsbad Fish and
Wildlife Office, 6010 Hidden Valley
Road, Carlsbad, CA 92011. Please
submit any new information, materials,
comments, or questions concerning this
finding to the above street address.
FOR FURTHER INFORMATION CONTACT: Jim
Bartel, Field Supervisor, Carlsbad Fish
and Wildlife Office (see ADDRESSES); by
telephone at 760–431–9440; or by
facsimile at 760–431–9624. If you use a
telecommunications device for the deaf
(TDD), please call the Federal
Information Relay Service (FIRS) at
800–877–8339.
SUPPLEMENTARY INFORMATION:
Background
Section 4(b)(3)(B) of the Endangered
Species Act of 1973, as amended (Act;
16 U.S.C. 1531 et seq.), requires that, for
any petition to revise the Federal List of
Endangered and Threatened Wildlife
and Plants that contains substantial
scientific or commercial information
that delisting the species may be
warranted, we make a finding within
12 months of the date of receipt of the
petition. In this finding, we will
determine that the petitioned action is:
(1) Not warranted, (2) warranted, or (3)
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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 List 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 12-month
findings in the Federal Register.
Previous Federal Actions
We listed Stephens’ kangaroo rat as
endangered on September 30, 1988
(53 FR 38465). We published a draft
recovery plan for the Stephens’
kangaroo rat on June 23, 1997 (62 FR
33799; Service 1997, pp. 1–71), but it
has not been finalized. The draft
recovery plan provides recovery
guidance and a benchmark for delisting
the species (Service 1997, p. 53),
consisting of:
(1) Establishment of a minimum of
five reserves, one of which is ecosystembased, in western Riverside County,
California, that encompass at least 6,675
hectares (ha) (16,500 acres (ac)) of
occupied habitat that are permanently
protected, funded, and managed; and
(2) Establishment of two ecosystembased reserves in San Diego County,
California, one in the Western
Conservation Planning Area and one
reserve in the Central Conservation
Planning Area, which are permanently
protected, funded, and managed.
Neither criteria have been met at this
time. Discussion of the criteria and their
applicability are discussed in the
Recovery Planning and Implementation
section below.
On May 1, 1995, we received a first
petition, dated April 26, 1995, from the
Riverside County Farm Bureau (RCFB)
requesting that the Stephens’ kangaroo
rat be removed from the Federal List of
Endangered and Threatened Wildlife (in
other words, delisted) under the Act.
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The petition included supporting
information stating that there were
original data errors and that the
assumptions used by the Service
resulted in underestimating the
numbers and range of the species and
overestimating the amount of habitat
lost. We acknowledged the receipt of the
petition in a letter to the RCFB, dated
June 12, 1995. On August 13, 1997, the
RCFB sent us an inquiry regarding the
status of the delisting petition and
requesting clarification as to whether we
had the funds or staff to respond with
a 90-day finding on the petition. We
sent a letter to the RCFB on August 26,
1997, stating that we were unable to
review the petition and publish our 90day finding due to limited resources.
We also provided the RCFB with
additional information concerning our
Listing Priority Guidance for Fiscal Year
1997.
On February 25, 2002, we received a
second petition from Mr. Robert Eli
Perkins, without reference to his
affiliation, dated February 22, 2002, to
delist the Stephens’ kangaroo rat. We
sent a letter acknowledging the receipt
of the second petition to Mr. Perkins on
August 6, 2002. The second petition was
nearly identical to the petition
submitted by the RCFB in 1995, in that
the 2002 petition provided the same
information and requested the same
action. We treated the second petition as
a re-submittal of the first petition rather
than a formal second petition.
On April 21, 2004, we announced our
90-day finding that the petition
presented substantial information to
indicate that the petitioned action may
be warranted (69 FR 21567), and we
initiated a status review of Stephens’
kangaroo rat under section 4(b)(3)(A) of
the Act. We also announced our
intention to complete a 5-year review of
the status of the species as required
under section 4(c)(2)(A) of the Act. We
requested scientific and commercial
data and other information regarding the
status of and threats to Stephens’
kangaroo rat.
The Riverside County Farm Bureau
filed a complaint on December 14, 2009
(CV 09–09162 CBM (OPx)) citing our
failure to publish a 12-month finding on
their petition to delist Stephens’
kangaroo rat. We reached a settlement
agreement with the plaintiffs on May 7,
2010, in which we agreed to submit to
the Federal Register a 12-month finding
on the plaintiff’s petition by July 30,
2010.
This notice constitutes the 12-month
finding on the February 25, 2002,
petition (which we treated as a resubmittal of the May 1, 1995, petition)
to delist the Stephens’ kangaroo rat.
Species Information
Species Description and Taxonomy
Stephens’ kangaroo rat (Dipodomys
stephensi Merriam) is a small, nocturnal
mammal. Kangaroo rats are more closely
related to squirrels than mice or rats and
constitute a distinct group of rodents
belonging to the family Heteromyidae.
Kangaroo rats are burrow-dwelling,
seed-eating animals that inhabit arid
and grassy habitats in western North
America. They are characterized by furlined, external cheek pouches used for
transporting seeds; large hind legs for
rapid, bi-pedal, saltatorial (leaping)
locomotion; relatively small front legs;
long tails; and large heads.
Stephens’ kangaroo rat was first
described as Perodipus stephensi based
on a specimen collected near
Winchester, Riverside County,
California (Merriam 1907, p. 78). As part
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of a major study of kangaroo rats in
California, Grinnell (1919, p. 203; 1922,
p. 7) found no good grounds for
retaining the genus Perodipus. As a
consequence of these findings, Grinnell
(1921, p. 95) published the currently
recognized name Dipodomys stephensi.
The Integrated Taxonomic Information
System (ITIS 2010, TSN 180247) and
more recent checklists continue to
recognize Dipodomys stephensi as a
distinct species (Baker et al. 2003, p. 13;
Bisby et al. 2010).
Geographic Range and Status
Stephens’ kangaroo rat typically
occurs at lower elevations in flat or
gently rolling grasslands of the dry
inland valleys west of the Peninsular
Ranges of southern California, in
western Riverside and northern and
central San Diego Counties (Grinnell
1922, p. 67; Lackey 1967a, p. 315;
Bleich 1973, p. 46; Bleich and Swartz
1974, pp. 208–210; O’Farrell et al. 1986,
pp. 187–189; O’Farrell and Uptain 1989,
p. 1; Pacific Southwest Biological
Services, Inc. 1993, pp. 4–36; Ogden
Environmental and Energy Services Co,
Inc. (Ogden) 1997, p. 3). This historical
range is small for rodents in general,
and particularly for kangaroo rats (Price
and Endo 1989, p. 294). At the time of
listing in 1988, the Stephens’ kangaroo
rat’s geographic range was reported as
encompassing the Perris, San Jacinto,
and Temecula Valleys in western
Riverside County (Temecula Valley was
mistakenly reported as located in San
Diego County), and the San Luis Rey
Valley in San Diego County (53 FR
38465). At listing, Stephens’ kangaroo
rat was known from 11 general areas,
and, currently, Stephens’ kangaroo rat is
found in 15 areas (see Table 1 below).
TABLE 1—GEOGRAPHICAL AREAS OF KNOWN STEPHENS’ KANGAROO RAT POPULATIONS AT LISTING (1988) AND AT
PRESENT (2010)
At listing
At present
Riverside County
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Kabian Park .............................................................................................
known ............................................
considered nonviable.
Lake Mathews/Estelle Mtn ......................................................................
Lake Skinner/Domenigoni Valley ............................................................
Motte Rimrock .........................................................................................
Potrero Valley ..........................................................................................
San Jacinto/Lake Perris ..........................................................................
Steele Peak .............................................................................................
Sycamore Canyon/March Air Force Base (AFB)* ..................................
known
known
known
known
known
known
known
Corona/Norco ..........................................................................................
Anza/Cahuilla (i.e., Silverado Conservation Bank) .................................
unknown ........................................
unknown ........................................
extant.
extant.
extant.
extant.
extant.
extant.
extant, Sycamore Canyon portion
considered nonviable.
considered nonviable.
extant.
............................................
............................................
............................................
............................................
............................................
............................................
............................................
San Diego County
Lake Henshaw .........................................................................................
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TABLE 1—GEOGRAPHICAL AREAS OF KNOWN STEPHENS’ KANGAROO RAT POPULATIONS AT LISTING (1988) AND AT
PRESENT (2010)—Continued
At listing
Ramona Grasslands ................................................................................
Rancho Guejito ........................................................................................
MCBCP (Camp Pendleton) .....................................................................
Fallbrook ..................................................................................................
At present
unknown ........................................
unknown ........................................
known ............................................
known ............................................
extant.
extant.
extant.
extant.
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* The SKR Management Area on the former March AFB is not a reserve at this time (2010).
Populations of Stephens’ kangaroo rat
continue to persist in areas throughout
the species’ native range, despite
fragmentation. Since listing, additional
populations have been found near
Corona/Norco and Anza/Cahuilla (i.e.,
Silverado Conservation Bank) in
western Riverside County, and Rancho
Guejito and Ramona Grasslands in San
Diego County, extending distribution
records to the northwest, east, and south
of areas known at the time of listing
(Montgomery 1990, p. 3; Montgomery
1992, p. 3; Pacific Southwest Biological
Services, Inc. 1993, pp. 4–39; Ogden
1997, p. 11). Although discovered after
listing, it is likely the four additional
populations were extant at the time of
listing and were detected as a result of
more focused surveys and consultations
subsequent to listing. The populations
identified after 1988 (subsequent to our
listing of the species) are located near
the periphery of the Stephens’ kangaroo
rat’s known range at the time of listing
and are considered new records of
occurrence and not a range expansion of
the Stephens’ kangaroo rat.
To date, no rangewide assessment has
been conducted to estimate the
population size and indices of
abundances (e.g., minimum number
alive index for Stephens’ kangaroo rat
across the species’ range). Surveys for
Stephens’ kangaroo rat necessary to
derive useful population estimates are
difficult to conduct due to their
nocturnal habits and limited time above
ground (see Biology section below). In
fact, very few studies have focused on
the distribution of habitats and
populations throughout the animal’s
range (Thomas 1975, p. 1; O’Farrell and
Uptain 1989, p. 1), and much of the
distributional information is in the form
of unpublished presence or absence
survey reports at particular sites from
short-term live-trapping studies
provided to landowners or public
agencies (Price and Endo 1989, p. 294).
More recent information has come from
localized area-specific survey reports
such as from Anza/Cahuilla and Potrero
Valleys (Western Riverside Multiple
Species Habitat Conservation Plan
Biological Monitoring Program, April
2009). Because live-trapping
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methodologies vary and result in
different capture probabilities, survey
results across studies are difficult to
interpret in terms of population
estimates. However, such methodologies
are useful for determining occupied
habitat and detecting changes in species
distribution.
Suitable Stephens’ kangaroo rat
habitat has been mapped and
categorized using a variety of different
classification schemes, including
categories such as occupied, potentially
occupied, and probably occupied.
Although mapping of ‘‘occupied’’ habitat
has been the most common method
used for assessing the status of
Stephens’ kangaroo rat, it can be
problematic, as not all areas have been
mapped, and most areas have not been
mapped over time to obtain information
about trends in the extent of habitat
occupied. More detailed and consistent
survey information is needed to
determine useful accurate and
defensible estimates of populations and
demographic trends for the Stephens’
kangaroo rat rangewide (Diffendorfer
and Deutschman 2003, p. 6).
For this 12-month status review and
finding, we identified all areas occupied
by Stephens’ kangaroo rat at any point
in time since the species was listed in
1988. Characterizations of these areas
form the basis of our understanding of
the known distribution of extant
occurrences of Stephens’ kangaroo rat
throughout its range. We refer to these
areas collectively as the ‘‘baseline
Stephens’ kangaroo rat occupied
habitat’’ throughout this finding. The
total baseline Stephens’ kangaroo rat
occupied habitat mapped for Riverside
and San Diego Counties is 22,221 ha
(54,909 ac). We consider this to be the
most current and best available
scientific information regarding the
known distribution of occurrences and
habitat of Stephens’ kangaroo rat
throughout the species’ range. In the
past, when conducting habitat and
mapping exercises we have used a 100meter grid to delineate habitat. Because
of improved mapping techniques, for
this baseline occupied habitat exercise,
we mapped the areas as accurately as
possible by more directly approximating
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the delineation of habitat areas rather
than using a 100-meter grid to map
habitat areas. We also digitized current
data and information available to us
from survey monitoring reports not
previously available. We acknowledge
that, due to varied mapping precision
and accuracy, as well as data and
resource constraints, there may be
discrepancies between this and previous
habitat acreage assessments.
Biology
Stephens’ kangaroo rat constructs
burrows to serve as sleeping quarters
and nesting sites (Bleich 1973, p. 73).
Burrows of Stephens’ kangaroo rat are
frequently found clustered in burrow
complexes (Brock and Kelt 2004, p. 52).
Burrow depths range between 23 and 46
centimeters (cm) (9 and 18 inches (in)),
and multiple burrow openings may be
adjoined. Burrow complexes consist of
a network of tunnels connecting
multiple entrances (Thomas 1975, p. 38;
O’Farrell 1990, p. 78), with tunnel
pathways corresponding to surface
runways (O’Farrell and Uptain, 1987,
p. 34). Individuals typically emerge
from their burrows after sunset; they
may be active at any time of night.
However, O’Farrell (pers. comm. 1986)
has observed that Stephens’ kangaroo
rats spend very little time (less than 1
hour) above ground each day and, when
they are above ground, they move
quickly between points.
Kangaroo rats, including Stephens’
kangaroo rat, are primarily granivores
(seed-eaters) and when above ground,
spend most of their time moving about
the surface, alternating between periods
of locomotion with stops to extract
seeds. Seeds are extracted from the soil
by digging with their forefeet and
balancing on their hind legs (Reichman
and Price 1993, p. 541), by direct
clipping of seed stalks and extracting
seeds from the felled seed heads of fruit
(Reichman and Price 1993, p. 542), or by
harvesting seeds directly from fruit that
lie within 15 to 20 cm (5.9 to 7.9 in) of
the ground (Reichman and Price 1993,
p. 543). Stephens’ kangaroo rats often
store large quantities of seeds, which
they initially collect in their external
cheek pouches and then transfer and
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bury in burrows or surface caches for
later consumption (Reichman and Price
1993, p. 543; Goldingay et al. 1997, p.
49). Seed caching may enable species of
Dipodomys to survive during temporary
shortages of food (Reichman and Price
1993, p. 543) or extreme seasonal
fluctuations in food availability (Morgan
and Price 1992, p. 2260). Although
seeds are their primary food source,
green vegetation and insects appear to
be important seasonal food and water
sources (Reichman and Price 1993, p.
540). Surface activity for Stephens’
kangaroo rat changes through the year,
reflecting seasonal rainfall and
subsequent vegetative productivity
(O’Farrell and Clark, 1987, p. 10).
Previous studies on Stephens’ kangaroo
rat indicate that late spring to early
summer breeding results in peak
population recruitment in August
(Lackey 1967b, p. 625; Bleich 1977, p.
1; O’Farrell and Clark 1987, p. 11).
The average litter size for the
Stephens’ kangaroo rat ranges from 2.7
to 2.8 individuals (Lackey 1967b, p. 625;
Price and Kelly 1994, p. 815). The
timing of breeding for Stephens’
kangaroo rat is highly variable, with
reproduction likely triggered by the
growth of vegetation subsequent to
winter rain (McClenaghan and Taylor
1993, pp. 642–643; Price and Kelly
1994, p. 813). Studies on Stephens’
kangaroo rat indicate a late spring to
early summer breeding season (Bleich
1977, p. 1; McClenaghan and Taylor, p.
636), although females on occasion may
remain reproductive until late fall as
long as food resources are adequate
(McClenaghan and Taylor 1993, pp.
642–643; Price and Kelly 1994, p. 813).
Observations suggest the possibility for
multiple litters during favorable
conditions (O’Farrell and Clark 1987,
p. 11).
Studies have estimated average
Stephens’ kangaroo rat survivorship in
the wild to be between 4.5 to 6.6
months, with some individuals living
for as long as 19 months (McClenaghan
and Taylor 1991, p. 12; Price and Kelly
1994, p. 815). However, these estimates
are probably low due to the limited
timeframe of the studies and the
inability to distinguish between actual
mortality and emigration. Adults appear
to have higher survival rates than
subadults.
Home ranges for Stephens’ kangaroo
rat vary according to physical habitat
features, season, food availability,
population density, and gender. Efforts
to characterize the home range size or
movements of Stephens’ kangaroo rat
have primarily relied on live trapping
(Thomas 1975, p. 7), or a combination
of live trapping and radio telemetry, to
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characterize movement patterns (Kelly
and Price 1992, p. 4; Price et al. 1994b,
p. 931). Estimates for mean home ranges
within a population vary between 0.02
and 0.13 ha (0.05 and 0.32 ac) (Thomas
1975, p. 49; Kelly and Price 1992, pp.
19–20). Home ranges generated from
live-trapping data are likely to be
underestimates for this species (Kelly
and Price 1992, p. 12), because the
presence of live traps likely changes
how the Stephens’ kangaroo rat moves
within its home range.
Stephens’ kangaroo rat is generally
considered highly sedentary (Price et al.
1994b, p. 935), but in one instance,
Price et al. (1994b, pp. 933–935)
recorded an individual moving over 1.0
km (0.6 mi) between trapping grids. The
median maximum distance moved by
Stephens’ kangaroo rat individuals
between capture sites was within 29 m
(96 ft) of the initial point of capture,
with 18 m (58 ft) as the median distance
moved between the first and last
monthly home-range center (for
individuals captured in 2 or more
months). Juveniles and adults were
found to maintain a home-range center
of 30 m (98 ft) (Price et al. 1994b,
p. 935). Males are more mobile than
females, and lactating females are
especially sedentary; dispersal distances
are similar for adults and juveniles.
O’Farrell (1993, p. 12) found that 40
percent of the population was mobile at
any one time and, in contrast to Price
et al. (1994b, pp. 933–935), observed
some movements in excess of 396 m
(1,300 ft) (O’Farrell 1993, p. 66).
Dispersal distances are usually less than
500 m (1,641 ft) (Price et al. 1994,
p. 936).
Habitat and Ecosystem
General habitat conditions for
Stephens’ kangaroo rat are described in
the literature (Bleich 1977, p. 8; Lackey
1967, p. 331; Price et al. 1991, p. 180;
Goldingay and Price 1997, p. 715;
Service 1997, pp. 9–11). Studies have
variously characterized habitat occupied
by this species as ‘‘sparse vegetation,
level or rolling topography, and soil that
is neither extremely dense nor largely
sand’’ (Lackey 1967, p. 318) or as
consisting of annual grasslands with
sparse cover of perennial shrubs (Price
and Endo 1989, p. 294). The term
‘‘grassland’’ is a generalization of this
species’ preferred vegetation
community; the Stephens’ kangaroo rat
appears to have a higher affinity for
vegetation communities dominated by
herbaceous plants (forbs) with a low
density of grasses than for a vegetation
community dominated by grasses
(O’Farrell and Clark 1987, p. 10;
O’Farrell and Uptain 1987, p. 9).
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Stephens’ kangaroo rat prefers grassland
communities dominated by forbs rather
than by annual grasses, as annual forbs
provide critical greens in the spring,
furnish temporary cover, produce large
seeds, and rapidly disintegrate after
drying, resulting in substantial patches
of bare ground (O’Farrell and Uptain
1989, p. 7; O’Farrell and Clark 1987, p.
10) that provide suitable conditions for
the species’ specialized mode of
locomotion (Bartholomew and Caswell
1951).
Stephens’ kangaroo rat reaches its
highest densities in grassland
communities dominated by forbs and
characterized by moderate to high
amounts of bare ground, moderate
slopes, and well-drained soils (O’Farrell
and Uptain 1987, pp. 35, 36; O’Farrell
1990, p. 80; Anderson and O’Farrell
2000, p. 12). Stephens’ kangaroo rat has
been found on 36 types of well-drained
soils, and more than 125 soil types
(Service 1996, p. 6) that are capable of
supporting annual grasses mixed with
forbs and shrub species.
Genetics
Genetic variability within and
between populations of Stephens’
kangaroo rat has been investigated based
on allozyme (protein) variation
(McClenaghan and Truesdale 1991
pp. 5–6, McClenaghan 1994, p. 12) and
through DNA analysis (Metcalf et al.
2001, p. 1239). Analysis of allozyme
variation indicates populations on
Marine Corps Base Camp Pendleton
(MCBCP) in San Diego County are
genetically similar to populations in
western Riverside County
(McClenaghan 1994, p. 25). In contrast,
mitochondrial DNA analysis (mtDNA)
of 16 populations across the range of
Stephens’ kangaroo rat found a higher
degree of genetic differentiation
(derived characteristics) between
occupied locations (Metcalf et al. 2001,
p. 1239) than found by the abovereferenced allozyme studies. Metcalf
et al.’s (2001, p. 1238) results infer that
gene flow might be restricted between
three hypothesized regions of potential
differentiation: North (corresponds to
northwestern and northeastern
Riverside County), central (corresponds
to central western Riverside County),
and south (corresponds to north and
central San Diego County), and
particularly between the south region
and the north and central regions.
However, based on inconclusive sample
sizes from each population (2 to 5
individuals per population), geographic
restriction in gene flow advanced by
Metcalf et al. (2001, p. 1241) should be
considered preliminary.
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Recovery Planning and Implementation
Section 4(f) of the Act directs us to
develop and implement recovery plans
for listed species. We published a draft
recovery plan for Stephens’ kangaroo rat
on June 23, 1997 (62 FR 33799) and
requested public comment on that draft
plan for 60 days, ending August 22,
1997. We have not yet prepared a final
recovery plan.
Section 4(f) of the Act requires the
Service to develop and implement
recovery plans for the conservation and
survival of endangered and threatened
species, unless we find that such a plan
will not promote the conservation of the
species. The Act directs that, to the
maximum extent practicable, we
incorporate into each plan: (1) Sitespecific management actions that may
be necessary to achieve the plan’s goals
for conservation and survival of the
species; (2) objective, measurable
criteria that, when met, would result in
a determination, in accordance with the
provisions of section 4 of the Act, that
the species be removed from the list;
and (3) estimates of the time required
and the cost to carry out the plan.
However, revisions to the List of
Endangered and Threatened Wildlife
(adding, removing, or reclassifying a
species) must reflect determinations
made in accordance with section 4(a)(1)
and 4(b) of the Act. Section 4(a)(1) of the
Act requires that the Secretary
determine whether a species is
endangered or threatened (or neither)
because of one or more of five threat
factors. Therefore, recovery criteria must
indicate when a species is no longer
endangered or threatened by the five
factors. In other words, objective,
measurable criteria, or recovery criteria,
contained in recovery plans must
indicate when an analysis of the five
threat factors under section 4(a)(1) of the
Act would result in a determination that
a species is no longer endangered or
threatened. Section 4(b) requires the
determination made under section
4(a)(1) as to whether a species is
endangered or threatened because of
one or more of the five factors be based
on the best available scientific and
commercial data.
Thus, while recovery plans are
intended to provide guidance to the
Service, States, and other partners on
methods of minimizing threats to listed
species and on criteria that may be used
to determine when recovery is achieved,
they are not regulatory documents and
cannot substitute for the determinations
and promulgation of regulations
required under section 4(a)(1) of the
Act. Determinations to remove a species
from the List of Endangered and
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Threatened Wildlife made under section
4(a)(1) of the Act must be based on the
best scientific and commercial data
available at the time of the
determination, regardless of whether
that information differs from the
recovery plan.
In the course of implementing
conservation actions for a species, new
information is often gained that requires
recovery efforts to be modified
accordingly. There are many paths to
accomplishing recovery of a species,
and recovery may be achieved without
all criteria being fully met. For example,
one or more criteria may have been
exceeded while other criteria may not
have been accomplished. The Service
may judge, however, that, overall, the
threats have been minimized
sufficiently, and the species is robust
enough to reclassify the species from
endangered to threatened or perhaps
delist the species. In other cases,
recovery opportunities may have been
recognized that were not known at the
time the recovery plan was finalized.
These opportunities may be used
instead of methods identified in the
recovery plan.
Information on the species may be
learned that was not known at the time
the recovery plan was finalized. The
new information may change the extent
that criteria need to be met for
recognizing recovery of the species.
Overall, recovery of species is a
dynamic process requiring adaptive
management, planning, implementing,
and evaluating the degree of recovery of
a species that may, or may not, fully
follow the guidance provided in a
recovery plan.
Thus, while the recovery plan
provides important guidance on the
direction and strategy for recovery, and
indicates when a rulemaking process
may be initiated, the determination to
remove a species from the List of
Endangered and Threatened Wildlife is
ultimately based on an analysis of
whether a species is no longer
endangered or threatened. The
following discussion provides a brief
review of recovery planning for
Stephens’ kangaroo rat, as well as an
analysis of the recovery criteria and
goals as they relate to evaluating the
status of the species.
The draft recovery plan identified a
proposed recovery strategy based on the
conservation of two types of reserves for
the Stephens’ kangaroo rat:
(1) Ecosystem-based reserves that are
not isolated from large expanses of
natural habitat and are anticipated to
retain their biological diversity, thus
needing only low levels of management;
and
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(2) Non-ecosystem-based reserves that
are biologically isolated for the most
part from large expanses of natural
habitat and are anticipated to lose
biological diversity, thus needing high
to intensive levels of management.
The proposed recovery strategy
recognized the importance of conserving
both types of reserves (i.e., sufficient
habitat) to maintain genetic and
phenotypic diversity, to conserve
representative populations of the
species, and to provide redundancy in
conserved populations to protect against
catastrophic events that could extirpate
the species from a significant portion of
its range (Service 1997, pp. 48–49; see
Factor A, D, and E discussions below).
While this strategy for the conservation
and recovery of Stephens’ kangaroo rat
is, in concept, still applicable and
reflective of the approach the Service
has used to guide conservation of
Stephens’ kangaroo rat, the recovery
criteria and objectives as outlined in the
1997 draft recovery plan have not been
revised to reflect information provided
during public comment or to
incorporate new and updated
information generated since then. In
addition, the goals and recovery criteria
are ecosystem-based, and, while this
approach generally addresses threats to
the species, it does not provide explicit
detail or guidance on determining
whether threats have been ameliorated.
Because ecosystem-based recovery
actions are likely insufficiently detailed
to address current and emerging threats
(see Factor A and E discussions below),
especially given new scientific
information, this suggests the need to
reevaluate the recovery strategy and
criteria for Stephens’ kangaroo rat. In
addition to current conservation efforts,
additional management approaches may
be needed to maintain sufficient habitat
requirements for the species’ long-term
survival. Further, the draft recovery
plan’s criteria do not identify
population or demographic goals that
would indicate that actions to
ameliorate specific threats have been
effective in ensuring the persistence of
Stephens’ kangaroo rat throughout its
range in the foreseeable future. Despite
the limitations discussed above, we
consider the draft recovery plan to serve
as an important document that sets out
conservation goals for Stephens’
kangaroo rat.
As discussed earlier, the 1997 draft
recovery plan recommended the
following objectives and criteria for
delisting the Stephens’ kangaroo rat
(Service 1997, p. 53):
(1) Establishment of a minimum of
five reserves, of which one is ecosystembased, in western Riverside County that
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encompass at least 6,675 ha (16,500 ac)
of occupied habitat that are permanently
protected, funded, and managed (refer
to Western Riverside County—Stephens’
Kangaroo Rat Habitat Conservation Plan
(HCP) under Factor A below); and
(2) Establishment of two ecosystembased reserves in San Diego County, one
in the Western Conservation Planning
Area and one reserve in the Central
Conservation Planning Area, that are
permanently protected, funded, and
managed (refer to San Diego County
sections under Factor A below).
The goal of Criterion 1, conserving at
least 6,675 ha (16,500 ac), is linked to
addressing the primary threat of habitat
loss through urbanization. Criterion 2 is
linked to threat of habitat loss and
fragmentation and deleterious effects of
small population size for the Stephens’
kangaroo rat through conserving the
geographic distribution, and phenotypic
and genetic diversity, of the species
across its known range.
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Criterion 1
The primary objective identified in
the draft recovery plan is to protect and
maintain sufficient populations and
habitat of the Stephens’ kangaroo rat to
allow the removal (delisting) of this
species from the Federal List of
Threatened and Endangered Wildlife
under the Act (Service 1997, p. 52). At
the time of listing, the primary threat to
the Stephens’ kangaroo rat was direct
habitat loss due to urban and
agricultural development. The goal of
Criterion 1, conserving at least 6,675 ha
(16,500 ac), is linked to addressing the
primary threat of habitat loss through
urbanization. However, because smaller,
more isolated, non-ecosystem-based
reserves were expected to be inherently
unstable due to their configurations and
current or future isolation from
surrounding natural habitat due to the
then existing or anticipated
development, they were expected to
require intensive management (Service
1997, p. 54). Additionally, establishing
a minimum of three ecosystem-based
conservation units (Service 1997, p. 54),
one ecosystem-based conservation unit
in western Riverside County (Criterion
1) and two in San Diego County
(Criterion 2, see below) was thought
appropriate to address the deleterious
effects of diminishing biological
diversity associated with small,
biologically isolated reserves. Because
western Riverside County was the area
where Stephens’ kangaroo rat was most
threatened by existing and future
urbanization, the maintenance of habitat
quality and suitability there was
considered essential for the
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conservation of this species (Service
1997, p. 49).
Since drafting Criterion 1 in 1997, we
have worked with private landowners
and local, State, and Federal partners to
develop and implement actions to
reduce threats and provide for the longterm conservation of the Stephens’
kangaroo rat. The primary mechanism
for implementing recovery actions for
the Stephens’ kangaroo rat has been
through a regional habitat conservation
plan in western Riverside County called
the Riverside County Habitat
Conservation Agency’s Habitat
Conservation Plan for the Stephens’
Kangaroo Rat in Western Riverside
County (the HCP) (see Western Riverside
County—Stephens’ Kangaroo Rat
Habitat Conservation Plan (HCP)
below). Through this regional HCP (and
other cooperative management
agreements and conservation plans), a
Stephens’ kangaroo rat core reserve
system, plus additional lands for the
benefit of Stephens’ kangaroo rat, is now
dedicated to the conservation of the
Stephens’ kangaroo rat in western
Riverside County.
Based on our analysis of baseline
Stephens’ kangaroo rat occupied habitat
within the western Riverside County
HCP area (Service 2010; see Table 2
below), the Stephens’ kangaroo rat core
reserves (not including the Potrero
Valley or March Air Force Base portion
of the Sycamore Canyon/March Air
Force Base Reserve) encompass 4,971 ha
(12,568 ac) of baseline occupied habitat.
Including Potrero Valley lands, 5,911 ha
(14,606 ac) is currently in conservation
within western Riverside County.
Although management is required,
Potrero Valley lands could serve to meet
the ecosystem-based reserve portion of
this criterion. These protected areas of
baseline occupied habitat capture the
geographic distribution of Stephens’
kangaroo rat within western Riverside
County. While the acquisition of lands
in Stephens’ kangaroo rat core reserves
has largely ameliorated the threats of
habitat loss due to urban development
identified at the time of listing, Criterion
1 also specifies that these reserves be
permanently protected, funded, and
managed to maintain habitat suitability
and ensure the long-term survival of
Stephens’ kangaroo rat. These
components of Criterion 1 have yet to be
fully implemented (see following
discussion and Western Riverside
County—Stephens’ Kangaroo Rat
Habitat Conservation Plan (HCP) section
below).
Endowments for management of four
of the core reserves (Lake Mathews/
Estelle Mountain, Lake Skinner/
Domenigoni Valley, Motte Rimrock, and
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51209
Potrero Valley) and for Sycamore
Canyon Wilderness Park are provided
either through the Metropolitan Water
District of Southern California, the HCP,
or the Western Riverside County
Multiple Species Habitat Conservation
Plan (MSHCP). The 1997 draft recovery
plan indicated intensive management of
non-ecosystem-based reserves in
western Riverside County would be
required, but the draft plan did not
identify specific goals or objectives to
assess the effectiveness of management
and to evaluate the response of
populations of Stephens’ kangaroo rat to
management actions. As discussed
under the Factor A analysis below,
recent surveys (dates range from 1991 to
2006) indicate that the amount of
occupied habitat on some of the
Stephens’ kangaroo rat core reserves has
decreased over time, and monitoring
efforts are not yet sufficient to
determine Stephens’ kangaroo rat
population trends within the 5,911 ha
(14,606 ac) of conserved baseline
occupied habitat. This indicates that
current management may not be
effective and that further monitoring is
needed to evaluate the effectiveness of
ongoing conservation efforts. Therefore,
we conclude that the primary goal of
Criterion 1 for delisting as described in
the 1997 draft recovery plan has not yet
been fully met.
Criterion 2
Criterion 2 for delisting recommends
the establishment of two ecosystembased reserves, one in western and one
in central San Diego County that are
permanently protected, funded, and
managed. The draft recovery plan
defines an ecosystem-based reserve as
‘‘not isolated from large expanses of
natural habitat’’ and needing ‘‘only
minimal management due to the
integrity of the natural system.’’
Criterion 2, similar to Criterion 1, was
meant to address the threat of habitat
loss to the Stephens’ kangaroo rat and
to conserve the geographic distribution,
and phenotypic and genetic diversity, of
the species. Criterion 2 is linked to the
threat of habitat loss and fragmentation
and to the deleterious effects of small
population size for the Stephens’
kangaroo rat through conserving the
geographic distribution, and phenotypic
and genetic diversity, of the species
across its known range. Since the draft
recovery plan was written, additional
populations have been discovered in
Ramona Grasslands and Rancho Guejito
(see Geographic Range and Status
section above). Additionally, Criterion 2
was developed to guard against the
deleterious effects of diminishing
biological diversity associated with
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small, biologically isolated reserves (see
Small Geographic Range and Population
Size under Factor E below) by
establishing larger ecosystem-based
reserves.
The 1997 draft recovery plan did not,
however, identify an acreage
requirement in its definition of an
ecosystem-based reserve. Rather, the
draft plan indicated that ecosystembased reserves should be surrounded by
large expanses of natural habitat, which
would allow them to retain their
biological diversity and require only
minimal management to promote the
relatively rapid recovery of Stephens’
kangaroo rat in the wild (Service 1997,
p. 49). Based on our analysis of baseline
Stephens’ kangaroo rat occupied habitat
in San Diego County (Service 2010),
only populations of Stephens’ kangaroo
rat at Lake Henshaw, at Rancho Guejito,
or on Camp Pendleton and Detachment
Fallbrook are likely large enough or are
surrounded by sufficient natural habitat
to meet this criterion, and currently
none of these areas are permanently
protected and managed (see discussion
under Factor A below).
The Stephens’ kangaroo rat occupied
habitat and surrounding natural lands
on Camp Pendleton and Detachment
Fallbrook may meet the intent of the
draft recovery plan for an ecosystembased reserve in western San Diego
County. However, as discussed below
under our Factor A analysis below, most
areas of known Stephens’ kangaroo rat
occupied habitat are threatened by
habitat degradation from encroachment
of nonnative grasses and succession to
more shrub-dominated communities,
and even the largest Stephens’ kangaroo
rat populations may not be sustained
over the long term without high to
intensive management. Thus, we
conclude that the criterion to establish
ecosystem-based reserves that are
protected, funded, and managed within
western or central San Diego County has
not been met.
Our review of the recovery criteria
from the draft recovery plan for
Stephens’ kangaroo rat indicates that
while both types of reserves have been
established that help to ameliorate the
threat of urban development, the criteria
have not been fully met because
management necessary to maintain
habitat suitability is not yet in place. We
also conclude that while the criteria
appropriately indicate the need for
habitat protection and intensive
management of reserves, they are
outdated and no longer adequately
address the current threats to the
species discussed below.
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Summary of Information Pertaining to
the Five Factors
Section 4 of the Act (16 U.S.C. 1533),
and its implementing regulations (50
CFR 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.
We must consider these same five
factors in delisting a species. We may
delist a species according to 50 CFR
424.11(d) if the best available scientific
and commercial data indicate that the
species is neither endangered nor
threatened for the following reasons:
(1) The species is extinct;
(2) The species has recovered and is
no longer endangered or threatened; or
(3) The original scientific data used at
the time the species was classified were
in error.
In making this finding, information
pertaining to the Stephens’ kangaroo rat
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 the petition we considered and
evaluated the best available scientific
and commercial information.
The petition did not contain
substantial information regarding the
biological status of Stephens’ kangaroo
rat or provide significant new
information as to current or future
threats to the species. Additionally, the
petition did not provide a
comprehensive review of the status of
the species or provide evidence
suggesting that the original listing was
in error.
Factor A. The Present or Threatened
Destruction, Modification, or
Curtailment of Its Habitat or Range
The 1988 listing rule identified
widespread habitat loss and a
fragmented distribution of the species
due to historical agriculture practices
and urban development as primary
threats to the Stephens’ kangaroo rat
(53 FR 38465, September 30, 1998). We
considered urban and agricultural
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development, grazing, and off-highway
vehicles (OHVs) to be significant and
potentially rangewide threats to the
long-term persistence of Stephens’
kangaroo rat at that time. These threats
continue for Stephens’ kangaroo rat
predominantly through habitat
modification and curtailment impacts,
compared to direct habitat loss.
The 2002 petition did not present any
significant new information regarding
the present or threatened destruction,
modification, or curtailment of habitat
and range of the species.
Habitat Destruction and Modification by
Urbanization and Land Use Conversion
The habitat and range of Stephens’
kangaroo rat has been reduced over
time. The species likely once occurred
throughout annual grassland or sparse
coastal sage scrub communities of the
Perris and San Jacinto Valleys and up
adjoining washes in southern California.
As flat lands were developed or
converted into agriculture, the species
likely became isolated to low rolling
hills and level ridge tops. With the
arrival of Spanish ranchers and agrarian
practices (i.e., before 1938), native
perennial bunchgrass vegetation was
replaced by annual grasslands and ever
since (i.e., in the later portion of the
20th century) has been increasingly
replaced by degraded annual grasslands
(see Factor E discussion below). Price
and Endo’s (1989, p. 299) study revealed
that the species suffered severe habitat
loss and fragmentation throughout a
core area of its range over the past
century, due primarily to agricultural
and urban development. In addition,
O’Farrell and Uptain’s (1989, p. 5)
assessment of the population and
habitat status of the Stephens’ kangaroo
rat throughout most of its range, which
was available just after the 1988 listing,
corroborated the threats from habitat
loss and fragmentation to the species.
They found that about 58 percent of
previously known populations were
extirpated due to human development
and that many of the extant populations
remained only in small and isolated
areas. The petition asserted that we
grossly over exaggerated the amount of
habitat lost. However, the petitioner did
not provide, and we do not possess, any
new scientific or commercial data
indicating that our original estimates of
habitat loss were overestimations or
were made in error.
In the 1988 final listing rule, we
estimated the amount of suitable habitat
(but not necessarily occupied habitat)
for the Stephens’ kangaroo rat prior to
20th-century agriculture was 124,775 ha
(308,195 ac) in western Riverside
County (53 FR 38467; Price and Endo
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1989, p. 296). By 1984, the quantity of
suitable habitat was reduced by
approximately 60 percent to 50,518 ha
(124,779 ac) (Price and Endo 1989, p.
296; 53 FR 38467). No similar estimates
of reduction of suitable habitat for
Stephens’ kangaroo rat were available
for San Diego County at that time, but
we surmise a roughly equivalent
magnitude of loss occurred
concomitantly in San Diego County,
given land use conversion to agriculture
in the early 20th century throughout the
grasslands of southern California.
Habitat modification and
fragmentation involves both reduction
in size and increased isolation of
habitats. Most extant populations of
Stephens’ kangaroo rat were considered
isolated from one another at the time of
the species’ 1988 listing and that pattern
of fragmentation has been reinforced
due to ongoing urbanization and land
use conversions. Occupied Stephens’
kangaroo rat sites, especially in the
western portions of the range, have
become increasingly isolated by
surrounding urban and agricultural
development. In some cases, occupied
sites may be too fragmented to sustain
viable populations of Stephens’
kangaroo rat (Burke et al. 1991, pp. 28–
29), suggesting that conservation of
these smaller isolated populations may
require enlarging patches of suitable
habitat or connecting patches via
conservation corridors. Similar to
habitat loss, habitat fragmentation
affects the persistence of populations or
a species within habitat fragments
(Wilcove et al. 1986, pp. 237–238, 246–
252; Morrison et al. 1992, pp. 43–47;
Noss et al. 1997, pp. 99–103; see Factor
E discussion below).
Further, direct conversion of habitat
by discing, burning, plowing, and
grading, and wildfire suppression fuel
reduction activities associated with
human use and agricultural practices
across the range of the species, can
result in habitat degradation of suitable
and occupied sites for Stephens’
kangaroo rat. Deep discing may destroy
the burrows of Stephens’ kangaroo rat
and degrade remaining vegetation.
Although in some instances the open
nature of plowed fields and farm access
roads has been shown to encourage
occupancy by the Stephens’ kangaroo
rat where fields are located near or
adjacent to occupied habitat, we have
little additional information to evaluate
the potential frequency of reoccupation
of abandoned agricultural lands or
persistence of populations on
abandoned agricultural lands. MooreCraig (1984, p. 5) found that Stephens’
kangaroo rats may recolonize a field
within 8 months after cessation of
cultivation. Although the threat of
habitat loss and modification from
agriculture land conversion was
considered less severe than the threat of
habitat loss from urbanization at the
time of listing (because Stephens’
kangaroo rats were found to reinvade
plowed fields if the agricultural usage
was abandoned (Thomas 1975, p. 46;
53 FR 38467)), the regularity and
persistence of these recolonization
events by Stephens’ kangaroo rat on
converted fields remains unknown.
Information on the frequency of
reoccupation of abandoned agricultural
lands, long-term persistence of these
populations on abandoned agricultural
lands following a recolonization event,
or the persistence of these lands as
occupied habitat will require longer
51211
term and directed investigations.
Regardless, agricultural practices may
still provide a persistent source of
nonnative vegetation and therefore
remain an ongoing threat to suitability
of habitat for Stephens’ kangaroo rat that
warrants future studies rangewide.
We estimated the baseline, from
which to gauge recent impacts,
Stephens’ kangaroo rat occupied habitat
for Riverside and San Diego Counties to
be 22,221 ha (54,909 ac). Of that
baseline, a total of 68 percent (15,059
ha/37,211 ac) is within Riverside
County and 32 percent (7,162 ha/17,698
ac) is in San Diego County. As of 2006,
a total of 1,433 ha (3,537 ac) of baseline
Stephens’ kangaroo rat occupied habitat
was lost directly to development (see
Table 2 below) in western Riverside and
San Diego Counties. Though 1,414 ha
(3,492 ac) were developed in Riverside
County from 1984 to 2006 (Service
2010), impacts from direct habitat loss
to urban development have mostly been
ameliorated due to existing conservation
efforts (see Recovery Planning and
Implementation above, and Factor A
and D discussions). In San Diego
County, little baseline Stephens’
kangaroo rat occupied habitat has been
developed (19 ha/46 ac), although the
potential for impact due to direct urban
development remains high, especially if
conservation efforts are not guaranteed
(see Factor A and D discussions).
Relative to previous discussions, it is
important to note that not all baseline
Stephens’ kangaroo rat occupied habitat
(22,221 ha/54,909 ac) is still currently
occupied, and this represents only a
small subset of the estimated amount of
suitable habitat (50,518 ha/124,779 ac)
for Stephens’ kangaroo rat indicated in
the 1988 listing rule.
TABLE 2—AMOUNT OF STEPHENS’ KANGAROO RAT HABITAT OCCUPIED, DEVELOPED, AND CONSERVED IN RIVERSIDE AND
SAN DIEGO COUNTIES
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BOH 1
ha (ac)
Total area
ha (ac)
Location
Riverside County .................................................
Within the HCP 2 ...........................................
Within MSHCP 3 ............................................
Potrero Valley ...............................................
Johnson Ranch .............................................
Anza/Cahuilla ................................................
San Diego County ...............................................
Lake Henshaw ..............................................
Ramona ........................................................
Rancho Guejito .............................................
Camp Pendleton ...........................................
Detachment Fallbrook ..................................
1,890,263 (4,670,942)
223,470 (552,206)
509,050 (1,257,889)
3,694 (9,128)
272 (671)
778 (1,922)
1,096,758 (2,710,148)
NA
NA
NA
50,692 (125,262)
3,606 (8,910)
15,059 (37,211)
12,568 (31,057)
15,059 (37,211)
940 (2,323)
1.9 (4.8)
202 (500)
7,162 (17,698)
4,331 (10,702)
67 (166)
1,224 (3,024)
422 (1,043)
1,118 (2,762)
BOH lost to
development
ha (ac)
1,414 (3,492)
1,071 (2,649)
1,413 (3,492)
0
0
0
19 (46)
2.5 (6.3)
0
0
0.1 (0.2)
16 (39)
1 Baseline
Stephen’s kangaroo rat occupied habitat (BOH).
Riverside County Habitat Conservation Plan for the Stephens’ Kangaroo Rat (HCP).
Riverside County Multiple Species Habitat Conservation Plan (MSHCP).
4 All lands under MSHCP, not just Additional Reserve Lands (ARL) lands.
2 Western
3 Western
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ha (ac)
6,275 (15,507)
4,971 (12,283)
4 213 (526)
940 (2,323)
1.9 (4.8)
150 (370)
1,510 (3,932)
0
67 (166)
0
422 (1,043)
1,102 (2,722)
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Conservation Efforts
Several habitat conservation plans
and other planning documents have
been developed and implemented in
western Riverside and San Diego
Counties since 1988. These plans
include: The Western Riverside County
Habitat Conservation Plan for the
Stephens’ Kangaroo Rat (the HCP) and
the Western Riverside County Multiple
Species Habitat Conservation Plan
(MSHCP) in Riverside County, as well
as the proposed San Diego North County
Multiple Species Conservation Plan
(North County MSCP), Marine Corps
Base Camp Pendleton’s (MCBCP)
Integrated Natural Resources
Management Plan, and the Naval
Weapons Station Seal Beach (NWSSB)
‘Detachment Fallbrook’ Integrated
Natural Resources Management Plan, all
in San Diego County. Additional local
conservation plans and partnerships or
active management agreements in both
Counties are ongoing within and outside
the regional habitat conservation plans.
In western Riverside and San Diego
Counties, existing conservation
planning efforts have slowed the rate of
unregulated loss of habitat to urban
development and agricultural
development. Currently, 36 percent, or
7,882 ha (19,477 ac) of the total baseline
Stephens’ kangaroo rat occupied habitat
rangewide is conserved through regional
habitat conservation plans and
conservation easements. Although the
intensity and magnitude of the threat
from direct habitat loss for Stephens’
kangaroo rat has been greatly
diminished through ongoing
implementation of habitat conservation
plans and conservation processes in
western Riverside County, and to a
lesser extent in San Diego County, both
habitat modification and curtailment are
currently impacting the species. In
considering the limitations and
inadequacies (see Factor D discussion
below) of ongoing efforts to implement
or maintain adaptive management
practices (not specifically mandated by
a habitat conservation plan’s terms and
conditions), the duration and extent of
habitat degradation and decreasing
habitat quality remains a rangewide
threat to the Stephens’ kangaroo rat.
Following is a discussion of the regional
plans in effect and what they provide
and do not provide regarding ongoing
threats of habitat destruction and
modification by urbanization and land
use conversion.
Western Riverside County—Stephens’
Kangaroo Rat Habitat Conservation Plan
(HCP)
Since the 1988 listing of the Stephens’
kangaroo rat, publicly reviewed,
regional habitat conservation planning
under section 10(a)(1)(B) of the Act has
guided recovery for the Stephens’
kangaroo rat, especially in western
Riverside County. The HCP in western
Riverside County provides for
protection of ‘‘core reserves’’ and
adaptive management of Stephens’
kangaroo rat habitat in order to
ameliorate impacts to the species from
habitat fragmentation and degradation
associated with development. The seven
core reserves for the Stephens’ kangaroo
rat were assembled from a combination
of State and federally owned lands,
lands already in conservation (e.g., in
open space preserves or through
conservation easements), lands acquired
by the Riverside County Habitat
Conservation Agency (RCHCA), and
other cooperative partnerships (Table 3);
Potrero Valley was added as a core
reserve on December 29, 2003, and
March Air Force Base was removed
through an authorized land exchange
(see Factor D discussion below).
TABLE 3—AREA CONSERVED BY CORE RESERVES UNDER THE STEPHENS’ KANGAROO RAT HABITAT CONSERVATION PLAN
(HCP) IN 1996. NOTE: POTRERO VALLEY WAS ADDED TO CORE RESERVE DESIGH LATER AND IS NOT INCLUDED IN
TOTAL AT DESIGNATION IN 1996; 270 HA (667 AC) OF SYCAMORE CANYON REMAINS IN CONSERVATION BUT IS CONSIDERED NONVIABLE
In hectares
Lake Skinner/Domenigoni Valley ............................................................................................................
Lake Mathews/Estelle Mountain .............................................................................................................
San Jacinto/Lake Perris ..........................................................................................................................
Sycamore Canyon/March Air Force Base ..............................................................................................
Steele Peak .............................................................................................................................................
Potrero Area of Critical Environmental Concern (ACEC) .......................................................................
Motte Rimrock Reserve ..........................................................................................................................
[Potrero Valley Reserve] .........................................................................................................................
5,325 ......................
4,550 ......................
4,424 ......................
1,013 ......................
709 .........................
403 .........................
258 .........................
[approx 3,694] ........
13,158.
11,243.
10,932.
2,502.
1,753.
995.
638.
[approx 9,128].
Total at designation in 1996 ............................................................................................................
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HCP Core Reserve
16,682 ....................
41,221.
Initiated with the ‘‘Short-Term’’ HCP
in 1990, and continued with the
approval in 1996 of the ‘‘Long-Term’’
HCP (which is the document we refer to
as the HCP in this finding), the HCP was
primarily envisioned to address the
need to minimize loss of known
occupied Stephens’ kangaroo habitat in
key localities (identified as ‘‘Study
Areas’’ in the Short-Term HCP) and
implemented as the seven core reserves
in 1996.
On May 2, 1996, we completed an
intra-agency biological opinion and
issued an Incidental Take Permit for a
30-year term for the HCP under section
10(a)(1)(B) of the Act. The HCP required
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the conservation of 6,070 hectares
(15,000 ac) of Stephens’ kangaroo rat
occupied habitat in seven core reserves
within the 216,083-ha (533,954-ac) plan
area and authorized, under section
10(a)(1)(B) of the Act, the loss of all of
the remaining occupied Stephens’
kangaroo rat habitat for development
(6,070 hectares (15,000 acres)) (RCHCA
1996, p. S–6). The Western Riverside
County Habitat Conservation Agency
(RCHCA), along with eight member
jurisdictions (Cities of Corona, Hemet,
Lake Elsinore, Moreno Valley, Murrieta,
Perris, Riverside, and Temecula), and
unincorporated areas within the plan,
are permittees.
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In acres
Near the time of permit issuance, the
HCP core reserve boundaries (i.e.,
within the conserved 16,682 ha/41,221
ac) included 5,042 ha (12,460 ac) of
Stephens’ kangaroo rat occupied habitat,
as reported by RCHCA (1996, p. S–9). In
a biological opinion dated May 2, 1996,
it was estimated that 11,307 acres of
occupied Stephens’ kangaroo rat
occupied habitat fell within the seven
core reserve boundaries. There is no
dataset currently available to reliably
quantify occupied habitat for Stephens’
kangaroo rat within the core reserves;
RCHCA, after years of incomplete
monitoring efforts, developed a reservewide monitoring protocol in July 2006,
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but it was suspended in 2007 (RCHCA
2007, p. 12). A newly revised
monitoring protocol has been developed
and is currently being implemented in
four of the reserves in 2010 (Lake
Skinner/Domenigoni Valley, Potrero
Valley, Potrero ACEC, and San Jacinto/
Lake Perris); adoption of the monitoring
protocol is anticipated on the other core
reserves in 2011 (Lake Mathews, Steele
Peak, Motte Rimrock, and at Sycamore
Canyon Wilderness Park) (Gail Barton
pers. comm., May 2010).
The largest four core reserves (Lake
Mathews/Estelle Mountain, San Jacinto/
Lake Perris, Lake Skinner/Domenigoni
Valley, and Potrero Valley) protect
several different habitat types and
provide for multiple species in addition
to Stephens’ kangaroo rat. Each of these
core reserves therefore contains
significantly more acreage than the
baseline Stephens’ kangaroo rat
occupied habitat. In 1996, there was the
recognition that the major Stephens’
kangaroo rat populations across the
species’ range would remain fragmented
and functionally isolated from one
another due to existing urban
development and topographic
conditions that precluded restoration of
natural connections once present under
historical conditions. Thus, core
reserves were expected to retain
biological diversity across the known
range of Stephens’ kangaroo rat, and
were anticipated to require intensive
active management (Service 1997,
p. 54).
Although losses to species and habitat
were anticipated, and we stated such
losses might reduce the viability of
remaining populations, we determined
in our biological opinion that
permanent management of Stephens’
kangaroo rat habitat to be conserved
provided a reasonable assurance that
Stephens’ kangaroo rat populations
within the HCP area would persist, and
that implementation of the HCP was not
likely to jeopardize the continued
existence of the Stephens’ kangaroo rat
(Service 1996, p. 15). Issuance of the
permit allowed the permanent loss of
50 percent of Stephens’ kangaroo rat
occupied habitat within the HCP area
and the loss of 31 percent of the
occupied habitat rangewide (Service
1996, p. 10).
Surveys indicate that some of the
baseline occupied habitat within core
reserves is no longer occupied by
Stephens’ kangaroo rat. Two core
reserves with the largest amount of
Stephens’ kangaroo rat occupied habitat
(Lake Mathews/Estelle Mountain (1,726
ha (4,264 ac)) and San Jacinto/Lake
Perris (1,473 ha (3,640 ac))) experienced
a decrease of 244 ha (602 ac) of
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Stephens’ kangaroo rat occupied habitat
by 2001 (RCHCA 2002, p. 1). Stephens’
kangaroo rat is considered extirpated
from 80 ha (197 ac) of the San Jacinto
Wildlife Area due to degradation of
habitat (Service GIS Data 2007, based on
Paulek 2002, p. 2). Between 1990 and
1996, development at Kabian Park (466
ha (1,153 ac) of occupied habitat known
at 1988 listing) resulted in significant
habitat fragmentation and its
elimination from core reserve
designation. Measures to minimize the
authorized take under the section 10
permits acknowledged conserving many
of the largest remaining populations
within the western Riverside portion of
the range. The conservation strategy for
the HCP was to capture a large enough
habitat base within which Stephens’
kangaroo rat populations could
naturally expand and contract in
response to environmental variability
with the core reserves. Key was proper
monitoring and management to
conserve Stephens’ kangaroo rat within
the system of isolated reserves, and
maintaining essential connectivity
within and between reserves for the
long-term maintenance of the ecosystem
captured within the reserves (Service
1996, p. 13).
Recent surveys (dates range from 1991
to 2006) indicate that the amount of
occupied habitat on some of the
Stephens’ kangaroo rat core reserves has
decreased over time, and that
monitoring efforts may still not be not
sufficiently detailed to provide a
reliable estimate of population sizes
(and thereby amount of occupied
habitat) across all reserves within the
HCP (RCHCA 2007, p. 11; Difffendorfer
and Deutschman 2003, p. 6). Further,
recent annual reports from the HCP state
that there are insufficient funds to
maintain adequate boundary fencing or
patrols around the core reserves
(RCHCA 2008), suggesting the lack of
enforcement ability (albeit voluntary) in
some areas within the HCP area.
In 2003, lands within the Sycamore
Canyon/March Air Force Base core
reserve, including a 405 ha (1,000 ac)
area known as the Stephens’ kangaroo
rat Management Area (SKR Management
Area), were released from the core
reserve for urban development. On
August 27, 2009, the Center for
Biological Diversity and San Bernardino
Valley Audubon Society filed a
complaint against the Service [Case No.
09–ev–1864 JAH POR (filed 8/27/09,
S.D. Cal.)], alleging that the release of
the SKR Management Area triggered the
consultation requirements of section 7
of the Act, constituted a major Federal
action significantly affecting the quality
of the human environment requiring
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appropriate environmental review
under the National Environmental
Policy Act (42 U.S.C. 4321 et seq.), and
was a material change to the HCP
requiring a formal amendment to the
section 10(a)(1)(B) permit. On April 22,
2010, a settlement agreement was filed
with the Court, in which the Service
agreed to rescind its December 29, 2003
approval of the release of the SKR
Management Area. Upon the Service
rescinding the release of the SKR
Management Area, the SKR
Management Area would be restored as
a preserve under the HCP and would be
subject to the restrictions applicable to
preserve lands under the section
10(a)(1)(B) permit and the HCP.
However, the settlement agreement has
not been approved by the Court and is
not currently in effect. Additionally,
other parties filed motions to intervene
in the lawsuit, and those motions are
currently pending before the Court.
Therefore, the conservation status of,
and the threat of potential loss or
destruction of the habitat in, the SKR
Management Area is currently
unknown. We believe that, regardless of
the pending Court decision, the longterm recovery of the Stephens’ kangaroo
rat is neither compromised nor
significantly enhanced by returning the
SKR Management Area to the core
reserve system.
Western Riverside County—Western
Riverside County MSHCP
Western Riverside County Multiple
Species Habitat Conservation Plan
(MSHCP) is a large-scale, multijurisdictional habitat conservation plan
that addresses 146 listed and unlisted
covered species, including Stephens’
kangaroo rat, within a 510,000-ha (1.26
million-ac) plan area. Within the
MSHCP area plan, there are sixteen
County of Riverside Area Plans. The
Service issued an incidental take permit
on June 22, 2004 (Service 2004), under
section 10(a)(1)(B) of the Act to 22
permittees under the MSHCP for a
period of 75 years. The Western
Riverside County Stephens’ Kangaroo
Rat HCP (see above) covers
approximately 216,084 ha (533,954 ac)
within the central portion of the MSHCP
area and remains its own distinct
habitat conservation plan. Thus, the
MSHCP Conservation Area is 140,426
ha (347,000 ac) of existing natural and
open space areas referred to as Public/
Quasi-Public Lands (e.g., State and
County Park lands, Federal lands)
within western Riverside County for the
listed and unlisted species and
complemented by an approximately
61,916 ha (153,000 ac) of new
conservation lands (‘‘Additional Reserve
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Lands, or ARL’’). The species-specific
objectives for Stephens’ kangaroo rat
under the MSHCP are consistent with
the requirements of the HCP to maintain
a minimum of 6,070 ha (15,000 ac) of
occupied Stephens’ kangaroo rat habitat
within the core reserves established by
the HCP, and to expand the existing
core reserves established by the HCP
(see Factor D discussion below).
Through cooperative management of
these existing conserved lands in
Western Riverside County (as provided
for in the MSHCP’s implementing
agreement (IA); MSHCP IA, p. 57) a total
of 7,875 ha (19,458 ac) of occupied
Stephens’ kangaroo rat habitat over the
75-year term of the MSHCP permit will
be conserved when the MSHCP is fully
implemented. We concluded in our
biological opinion that implementation
of the MSHCP was not likely to
jeopardize the continued existence of
the Stephens’ kangaroo rat because of
the avoidance, minimization, and
mitigation measures, and associated
monitoring and management
incorporated into the MSHCP and for
the conservation objectives set forth in
the IA (Service 2004, p. 311). Based on
the distribution of the Stephens’
kangaroo rat and protection and
management of the MSHCP
Conservation Area, we concluded that
habitat loss as described in the MSHCP
would not result in an appreciable
reduction in the numbers, reproduction,
or distribution of the species throughout
its range (Service, p. 311).
Although the precise configuration of
the 61,916 ha (153,000 ac) of Additional
Reserve Lands is neither mapped nor
precisely identified in the MSHCP,
textual descriptions within the bounds
of a 125,453-ha (310,000-ac) Criteria
Area that is interpreted through time as
implementation of the MSHCP proceeds
are expected. Based on the provisions of
the MSHCP, Additional Reserve Lands
of specific conservation value to
Stephens’ kangaroo rat will likely be
added to these core reserves: Lake
Mathews/Estelle Mountain, 519 ha
(1,281 ac); Lake Skinner/Domenigoni
Valley, 406 ha (1,003 ac); San Jacinto/
Lake Perris, 56 ha (140 ac); Motte
Rimrock, 41 ha (102 ac); Steele Peak,
292 ha (721 ac); and Potrero ACEC, 59
ha (146 ac). Beyond the already 6,276 ha
(15,507 ac) of conserved habitat in
western Riverside County, we expect
that the ongoing implementation of the
MSHCP will conserve an additional
1,501 ha (3,709 ac) of the baseline
Stephens’ kangaroo rat occupied habitat,
including 1,246 ha (3,079 ac) that are
linked to the existing reserves and 255
ha (630 ac) in a new reserve near Anza
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(Service 2010). The additional
conservation of occupied habitat
adjacent to the existing reserves and the
addition of one new reserve will
enhance the long-term viability of
Stephens’ kangaroo rat populations
within western Riverside County.
Through 2008, 130 ha (323 ac), or 9
percent, of the Additional Reserve
Lands (ARL ‘‘gains’’) that are linked to
the Stephens’ kangaroo rat core reserves
have been acquired and conserved
under the MSHCP (Service 2010). The
MSHCP provides for monitoring and
management on its Additional Reserve
Lands, an increased level of monitoring
on the core reserves established under
the HCP, and the potential for
acquisition of non-Stephens’ kangaroo
rat occupied habitat that abuts some
Stephens’ kangaroo rat populations near
the edge of the reserves, thus providing
a buffer to the effects of surrounding
urbanization (see Factor D discussion
below).
Additional Reserve Lands, both
within and outside the MSHCP
boundary, include habitat linked (i.e.,
within 500 meters (1,640 ft)) to the
existing Stephens’ kangaroo rat core
reserves (1,373 ha (3,393 ac)) and add
one additional core area in the Anza/
Cahuilla Valleys, which encompasses
the Silverado Mitigation Bank (261 ha
(645 ac)), and incorporates smaller
scattered habitat patches throughout the
MSHCP Conservation Area (541 ha
(1,336 ac)) (Dudek 2003, Table 9–2, p.
9–96; Service 2004, p. 309; Service
2008a, p. 1). Additional Reserve Lands,
which include baseline Stephens’
kangaroo rat occupied habitat within
500 m (1,640 ft) of the Stephens’
kangaroo rat core reserves, enhance the
probability of long-term Stephens’
kangaroo rat persistence within western
Riverside County and are thus
important to the recovery of the species.
Norco Hills, adjacent to the Santa Ana
River in the City of Norco, was found to
be occupied after the species was listed
in 1988, and included approximately
405 ha (1,000 ac) of occupied and
potentially occupied habitat (Dudek and
Associates 2003, p. M–203). The Norco
Hills population was considered to be
important to the conservation of
Stephens’ kangaroo rat, but by 2004, the
Norco Hills area was reduced by
approximately 46 percent to an
estimated 185 ha (457 ac) of highly
fragmented habitat due to ongoing or
pending development projects (Service
2004, p. 304). Offsite conservation to
address these impacts was primarily
concentrated at the Wilson Valley and
Silverado Mitigation Banks. Subsequent
to this development, the Norco Hills
area was considered to no longer have
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long-term conservation value for the
species, and as a result, it was
discounted as a targeted area of
conservation in the western Riverside
County planning process.
The threat of direct habitat loss of
Stephens’ kangaroo rat habitat in
western Riverside County from largescale development (intense urbanization
and land use conversion) is no longer
the predominant threat to the species as
stated in the final listing rule (53 FR
38465, September 30, 1988). Most, but
not all, proposed projects in western
Riverside County are limited to that
permitted under either the HCP or the
MSHCP. However, as the HCP and
MSHCP do allow for continued,
regulated development in Stephens’
kangaroo rat occupied habitat,
implementation of proposed and future
development projects under the HCP
and MSHCP will continue to result in
the destruction and modification of
Stephens’ kangaroo rat habitat (suitable
or occupied) within the plan areas.
Additionally, successful management of
the reserves is pivotal in avoiding
declines in the Stephens’ kangaroo rat
populations within the core reserves
and within the MSHCP plan area.
Connectivity and proper monitoring and
management were, and remain, essential
to the long-term viability of the
Stephens’ kangaroo rat.
In summary, western Riverside
County accounts for 68 percent, or
15,059 ha (37,211 ac), of total baseline
occupied habitat mapped for this
species. Of this, 6,276 ha (15,507 ac), or
41 percent, is currently held in
conservation, and the remaining 59
percent has previously been impacted
by urban development or may be subject
to future loss, modification, or
fragmentation from urban development.
San Diego County—Lake Henshaw and
Ramona Grasslands
A majority of Stephens’ kangaroo rat
occupied habitat in central and north
San Diego County is not conserved
currently. The lands supporting
Stephens’ kangaroo rat population at
Lake Henshaw are managed for water
conservation by a local government
agency, the Vista Irrigation District, and
although they are likely to remain
underdeveloped to protect the
watershed and delivery potential of the
agency’s mission, to our knowledge
there is no active management
specifically targeting Stephens’
kangaroo rat conservation; we currently
know of no projects that would result in
development or destruction of the
Stephens’ kangaroo rat habitat owned by
the District. Studies indicate that this
site likely supported the largest
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remaining contiguous population of
Stephens’ kangaroo rat within the
species’ entire range, with an estimated
4,600 ha (11,367 ac) of suitable habitat
occupied (O’Farrell and Uptain 1987,
p. 10). The current status of this
population in unknown and we are
aware of no surveys in this area since
1990.
Currently conserved areas on public
lands within San Diego County include
Ramona Grasslands and Ramona
Airport. Approximately 67 ha (166 ac)
of baseline Stephens’ kangaroo rat
occupied habitat in the Ramona
Grasslands have been conserved
through efforts by local jurisdictions, by
conservation organizations (The Nature
Conservancy and others), or through a
combination of public and private
ventures. There remain a few pockets of
development anticipated in Ramona
Grasslands within baseline Stephens’
kangaroo rat occupied habitat.
San Diego County—Military Lands and
Integrated Natural Resources
Management Plans (INRMPs)
Based on a recent analysis (Service
2010), we estimated approximately
1,540 ha (3,805 ac) of baseline Stephens’
kangaroo rat occupied habitat on
military lands at Marine Corps Base
Camp Pendleton (MCBCP) and Naval
Weapons Station Seal Beach
Detachment Fallbrook (NWSSB
Detachment Fallbrook, or ‘‘Detachment
Fallbrook’’) are conserved through
conservation planning agreements. This
accounts for approximately 20 percent
of the baseline Stephens’ kangaroo rat
occupied habitat in San Diego County.
Both military installations have
integrated natural resources
management plans (INRMPs) and
management actions specific to
Stephens’ kangaroo rat. INRMPs are
based, to the maximum extent
practicable, on ecosystem management
principles and provide for the
management of Stephens’ kangaroo rat
and its habitat while sustaining
necessary military land uses.
MCBCP adopted an INRMP in 2001
that was revised in 2007 (Marine Corps
2007, pp. 4–1 to 4–117), and the U.S.
Navy completed an updated INRMP for
Detachment Fallbrook in 2006 (U.S.
Navy 2006, pp. 4–1 to 4–130). These
INRMPs are largely ecosystem-based,
except where biological opinions under
section 7 of the Act direct speciesspecific actions. The Service and Marine
Corps are in consultation under section
7 of the Act on the Marine Corps’
programmatic upland plan to avoid and
minimize the effects of their activities
on federally listed upland species,
including Stephens’ kangaroo rat, but
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the plan is currently not finalized. We
anticipate that the species-specific
conservation benefits for Stephens’
kangaroo rat will outweigh all
anticipated incidental take from various
military training and facility
management activities. Detachment
Fallbrook’s INRMP incorporated
Stephens’ kangaroo rat management
practices described in the Wildland Fire
Management Plan (U.S. Navy 2003),
which underwent formal consultation
with the Service (Service 2003, FWS–
SD–3506.3). In addition to
implementation of conservation and
mitigation measures resulting from
section 7 consultations, INRMPs, Range
and Training Regulations (RTRs), and
other planning documents serve to
protect the species and its habitat on
MCBCP and Detachment Fallbrook.
Species-specific direction to guide
ongoing Stephens’ kangaroo rat
conservation and management can be
limited, as INRMPs may be superseded
by the military’s obligation to ensure
readiness of the Armed Forces and are
subject to discretionary funds and
planning.
Land uses on MCBCP and Detachment
Fallbrook pose a threat to Stephens’
kangaroo rat habitat in localized areas
where intense training, construction, or
foot/off-highway vehicle traffic
degrades, modifies, or fragments habitat.
Current land use also increases risks of
nonnative introduction and expansion,
and soil compaction, which may
threaten Stephens’ kangaroo rat in
portions of the military installations.
Although adequately avoided and
minimized, impacts to known occupied
Stephens’ kangaroo rat habitat may
occur. Ongoing and potential threats to
Stephens’ kangaroo rat populations on
MCBCP include project construction,
military training activities (including
off-road vehicle exercises), domestic cat
predation, and successional processes
(Service 1988; Price et al. 1995; Tetra
Tech, Inc. 1999).
A Stephens’ kangaroo rat monitoring
program was implemented at Camp
Pendleton from 1996 to 2002
(Montgomery et al. 1997, pp. 1–8;
Montgomery 2005b, pp. 1–27), and
updated in 2004 by the U.S. Geological
Survey (Brehme et al. 2006, p. 3). The
updated monitoring program is
designed to assess trends in the amount
of occupied habitat on the MCBCP and
guide Stephens’ kangaroo rat habitat
management activities carried out under
the INRMP.
Since the 1988 listing, the Marine
Corps has formally consulted on
military construction project impacts to
about 14 ha (34 ac) of occupied or
suitable Stephens’ kangaroo rat habitat
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on MCBCP. As a result, the Marine
Corps committed to offset the projected
temporary and permanent impacts by
establishing and managing the 21.5-ha
(53.1-ac) SKR Management Area in the
Juliet training area. Management of this
site to maintain open habitat preferred
by the Stephens’ kangaroo rat is
achieved through periodic burning with
prescribed burn practices. This site is
not set aside as a habitat preserve and
therefore may be subject to subsequent
training-related impacts over time.
It remains uncertain how ongoing
military training affects Stephens’
kangaroo rat on MCBCP. Training may
be compatible with Stephens’ kangaroo
rat to some extent by promoting areas
with limited vegetative cover, but
training may also negatively affect
Stephens’ kangaroo rat by compacting
soils, crushing burrows or individuals,
or promoting invasive plants that
degrade suitability of habitat for
Stephens’ kangaroo rat. Since the 1988
listing, the Marine Corps has instituted
Range and Training Regulations that
restrict ground-disturbing activities, offhighway vehicle use, and other training
activities within occupied Stephens’
kangaroo rat habitat (Marine Corps
2002). These restrictions are likely to
have reduced incidence of Stephens’
kangaroo rat mortality, disturbance,
injury, or habitat degradation caused by
training activities, although we
anticipate some impact is probably
occurring at a low rate.
Similar monitoring efforts for
Stephens’ kangaroo rat have been
conducted at Detachment Fallbrook
from 1990 to 1991 (Service 1993, p. 6),
2001 to 2002 (Montgomery et al. 2005,
p. 3), and 2002 to 2007 (U.S. Navy
2006a, p. 1–4; U.S. Navy 2007). Since
the 1988 listing, about 40 ha (99 ac) of
occupied or suitable Stephens’ kangaroo
rat habitat has been impacted by various
construction projects at Detachment
Fallbrook (Service 1995, 2003). Most
impacts related to construction projects
have been offset by habitat enhancement
at appropriate locations throughout
Detachment Fallbrook. These sites,
however, are not set aside as habitat
preserves and therefore may be subject
to subsequent impacts over time. An
additional 25 ha (63 ac) of occupied and
35 ha (86 ac) of suitable Stephens’
kangaroo rat habitat have been impacted
by fire control actions (Service 1995,
2003).
Successional processes may be
reducing the amount of available
Stephens’ kangaroo rat habitat on
Detachment Fallbrook, thereby
negatively affecting the Stephens’
kangaroo rat population there. Removal
of agriculture and military training
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activities, reduced grazing, and lower
fire frequencies may all have
contributed to the filling in of open
habitat suitable for Stephens’ kangaroo
rat, although quantification of this
habitat loss and identification of
processes involved have not been
adequately studied. Because
successional processes have been
identified as negatively affecting
Stephens’ kangaroo rat, disturbances,
including wildfires, prescribed fire,
ungulate grazing, and mechanical
vegetation reduction (discing), that open
up habitat or remove above-ground
vegetation in areas with soils suitable
for Stephens’ kangaroo rat may prove
beneficial to this species.
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San Diego County—North County
Multiple Species Conservation Plan
(MSCP) Planning Area and Rancho
Guejito
A draft North County MSCP plan has
the potential to contribute to the
recovery of the Stephens’ kangaroo rat
in north San Diego County, excluding
on military lands. A planning agreement
for the North County MSCP plan is
signed; the agreement may afford
limited protection to Stephens’
kangaroo rat and its habitat from
discretionary development and
construction impacts (NCCP Planning
Agreement No. 2810–2007–00205),
although these conservation measures
cannot be assured because the proposed
actions have been neither permitted nor
proven effective. Rancho Guejito, which
falls within the North County MSCP
planning area, is privately owned and
has approximately 1,219 ha (3,012 ac) of
baseline Stephens’ kangaroo rat
occupied habitat. Recently, Rancho
Guejito has been proposed for
development. The Service and San
Diego County have entered into
discussions with the landowners of
Rancho Guejito to address the
conservation and development issues
related to Stephens’ kangaroo rat
habitat. Rancho Guejito currently
remains subject to ongoing development
pressures.
Habitat Destruction and Modification by
Nonnative Ungulates
Grazing (and associated impacts from
crushing of burrows, trampling of
habitat and soil compaction,
introduction of nonnative grasses, and
conversion to less suitable vegetation
types) has historically impacted
Stephens’ kangaroo rat and its habitat
rangewide. Grazing of grasslands
associated either with commercial
grazing activities or with grazing
practices associated with habitat
management activities (i.e., under
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management plans specific to habitat
conservation plans) has been, and
remains, a land use practice in western
Riverside and San Diego Counties.
These two forms of grazing have
potential for differential impacts to
Stephens’ kangaroo rat.
Grazing for commercial practice has
been reduced significantly by urban
development and fragmentation and
from the change to dry land and
citriculture farming. At the time of the
1988 listing, commercial grazing was
conducted at high densities using both
sheep and cattle, occurred year round,
and was not managed for species
conservation value for Stephens’
kangaroo rat. Commercial grazing has
since been reduced, and where such
grazing still exists, impacts have been
lessened compared to when the species
was listed.
Grazing that is managed for the
purpose of improving habitat quality for
Stephens’ kangaroo rat is currently
practiced and is limited to certain
geographic areas within Stephens’
kangaroo rat occupied habitat. This form
of grazing follows specific
methodologies to avoid or significantly
reduce any negative impacts for
Stephens’ kangaroo rat (e.g., limited
number of grazing animals, typically
sheep; short duration (1 to 2 day
consecutive maximum); and conducted
in only certain seasons). Managed
grazing practices are used by RCHCA at
Lake Mathews/Estelle Mountain and
Lake Skinner, and by the Bureau of
Land Management and RCHCA at Steele
Peak. Grazing is allowed on Federal
lands at Detachment Fallbrook to
control nonnative grasses or as a means
of fire suppression (e.g., fire breaks).
Cattle grazing, however, has been
temporarily halted on Detachment
Fallbrook beginning in 2004. Although
cattle grazing is projected to be reinitiated in 2010 (C. Wolf, Detachment
Fallbrook, pers. comm. to M. Pavelka
CFWO, May 11, 2009), lack of grazing in
the interim has probably contributed to
increasingly dense grasslands on
Detachment Fallbrook that have
inhibited Stephens’ kangaroo rat’s
growth and movement. To offset the
temporary loss of the beneficial aspects
of cattle grazing, the Navy recently has
conducted limited mechanical
vegetation reduction activities to benefit
Stephens’ kangaroo rat on Detachment
Fallbrook (Navy 2008a, b).
Commercial grazing for purposes
other than habitat or vegetation
management may still occur in some
situations on private lands. Between
1987 and 1990, land management
changes and a reduction in grazing
pressure at the Lake Henshaw site
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appeared to promote a shift in the
vegetation type that led to an estimated
90 percent decrease in the Stephens’
kangaroo rat population (O’Farrell 1990,
p. 81; O’Farrell, 1997, p. 31). Mostly due
to the reduction in commercial grazing
pressures, which in some cases was
detrimental to habitat and in other cases
was beneficial, we now consider grazing
to no longer be a rangewide threat to
Stephens’ kangaroo rat, assuming
grazing is adequately managed.
Habitat Destruction and Modification by
Other Nonnative Species
Conversion of native vegetation to
nonnative annual grassland is a
potentially rangewide, high magnitude
threat to Stephens’ kangaroo habitat.
Increased dominance of nonnative plant
species, especially dense thatch-forming
grasses and Lepidium latifolium
(perennial peppergrass, or pepperweed)
reduces habitat suitability, by reducing
the abundance of forb-dominated
grassland habitat preferred by this
species, and by reducing necessary open
bare-ground habitat. Similarly, the
invasion of native perennial grasses
(through land use practices) or
conversion to dense stands of coastal
sage scrub through natural succession
can make the habitat less suitable for
Stephens’ kangaroo rat over time.
Several invasive, nonnative and
native grasses can reduce or otherwise
degrade Stephens’ kangaroo rat habitat
if they become established at high
densities (O’Farrell and Uptain 1989, p.
7), because their plant materials do not
rapidly break down after dying. The
nonnative grasses Schismus barbatus
(common Mediterranean grass) and
Vulpia myuros (foxtail fescue) do not
negatively influence habitat for
Stephens’ kangaroo rat, presumably
because they do not form persistent
dense mats like other nonnative grass
species (e.g., Bromus spp. (brome))
(O’Farrell 1993a, p. 6; O’Farrell 1997, p.
18). Consequently, natural or artificial
disturbances that remove or prevent the
development of dense ground cover or
succession of grassland communities to
later stage shrub communities may be
beneficial to Stephens’ kangaroo rat
(Price et al. 1994a, p. 9; O’Farrell 1997,
p. 30). Nonetheless, too much
disturbance (e.g., severe fire intensity
and excessive trampling) may be
detrimental (Tetra Tech 1999, pp. 2–15;
Haas and O’Farrell 2006, p. 34),
particularly if a high proportion of
individuals from a population perish
from these disturbances. Thus, to
maintain habitat suitability and
occupancy by Stephens’ kangaroo rat, in
areas dominated by nonnative
grasslands, regular management to
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reduce grass density and thatch buildup
is necessary.
Studies suggest that, when properly
managed, certain disturbance activities
such as grazing, brush removal, and
natural and human-caused fires may
reduce the threat of habitat modification
from nonnatives and help to maintain
the open habitat preferred by Stephens’
kangaroo rat. Fire has been shown to be
both beneficial and detrimental to
Stephens’ kangaroo rat. Price et al. 1995
(p. 15) found that at Lake Perris,
populations of Stephens’ kangaroo rat
respond positively to fire-induced
habitat alterations of areas less than 1 ha
(2.8 ac). Additionally, patchiness on a
relatively small spatial scale facilitates
recolonization because immigration
sources are nearby. Disturbance
associated with fire may reduce thatch
produced by nonnative species and
contribute to the maintenance of bare
ground required by the species (Price et
al. 1995, p. 56). Prescribed fires can be
employed to reduce invasive, nonnative
and native plants; however, because
most of the Stephens’ kangaroo rat
habitat is near urban and suburban areas
in western Riverside County, use of
prescribed fire is problematic and often
incompatible with urban and suburban
land uses.
There is concern that conversions of
occupied habitat from forb-dominated
grasslands, suitable for Stephens’
kangaroo rat, to perennial bunch-grassdominated grasslands, less suited to
Stephens’ kangaroo rat, have occurred
throughout the species’ range. Current
and future active management may be
required to maintain suitable forbdominated grassland and avoid
vegetation conversion or succession,
such as the vegetation changes that
occurred at Lake Henshaw. O’Farrell
(1990, pp. 80–81) suggests that, unless
intensive and sustained management is
undertaken to avoid this type of habitat
conversion and degradation to perennial
bunch-grass-dominated grasslands or
dense stands of coastal sage scrub, lower
densities of Stephens’ kangaroo rat will
occur. Fragmentation of populations
will result as patches of habitat become
unsuitable, and will render Stephens’
kangaroo rat populations much more
vulnerable to extirpation. Currently, the
Lake Henshaw site is not being managed
to control nonnatives; however, with
proper control of nonnatives, the Lake
Henshaw site could represent
approximately 5,100 ha (12,602 ac) of
potentially occupied habitat, which
would make it the largest, most
contiguous, and potentially the most
viable population of Stephens’ kangaroo
rat rangewide.
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The main effect of invasive species is
the decrease in habitat quality and
available forage for Stephens’ kangaroo
rat. Some habitat may be lost due to
nonnative (and native) grass invasion or
coastal sage scrub conversion resulting
in unsuitable habitat for the Stephens’
kangaroo rat. Presumably a certain
amount of invasive species is tolerable
when held in check with disturbance
activities such as certain grazing
regimes, brush removal, and managed
fires, but further investigations as to
what frequency and intensity and
degree of applicability are both ongoing
and needed to determine the long-term
benefit to Stephens’ kangaroo rat.
Currently, there is little active
management of habitat occurring across
the range of the species. The
maintenance of habitat conditions that
Stephens’ kangaroo rat requires is
essential for the conservation of this
species (Service 1997, p. 49).
Habitat Destruction and Modification by
Off-Highway Vehicles (OHVs)
At the time of the 1988 listing, OHV
use was described as a factor that
potentially reduces habitat suitability
(53 FR 38467, September 30, 1988).
OHVs directly damage plant
communities, as well as the soil crust
and the burrow systems of grounddwelling species such as Stephens’
kangaroo rat, thereby degrading the
species’ habitat (Bury et al. 1977, p. 16).
Trespassing by OHVs negatively
impacts Stephens’ kangaroo rat at Steele
Peak, Lake Mathews, and San Jacinto
core reserves, and results in degradation
of habitat. OHV trespassing and other
encroachments, such as illegal trash
dumping, trespassing on foot,
vandalism, and encroachment by
neighboring landowners, have been
reported as a chronic problem (RCHCA
2001a, p. 9; RCHCA 2002a, p. 10;
RCHCA 2004a, p. 10; RCHCA 2004b, p.
10; RCHCA 2006, p. 10). Efforts to
curtail these activities have been limited
and have not been successful due to
lack of support for adequate patrols,
limited available funding, differing land
use policies of landowners within the
core reserves, and lack of law
enforcement capabilities by the reserves’
managers. Overall, we consider OHV
use to remain a threat to Stephens’
kangaroo rat.
Summary of Factor A
At the time of listing, the major threat
to Stephens’ kangaroo rat habitat was
rangewide loss, degradation, and
fragmentation of habitat due to urban
and agricultural development. However,
since the species’ 1988 listing,
conservation measures, such as the
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51217
development and successful
implementation of habitat conservation
plans, have reduced the magnitude of
the threat of habitat loss due to urban
and agricultural development
throughout most of the range of the
Stephens’ kangaroo rat. Assembly of the
core reserves under the HCP considered
the isolation of small fragments of
Stephens’ kangaroo rat habitat at known
localities at the time of listing. The
successful implementation of habitat
conservation plans has resulted in a
total of 36 percent of baseline Stephens’
kangaroo rat occupied habitat being
conserved and protected from the threat
of loss to urban development. However,
urban development pressures remain on
a significant portion of baseline
occupied habitat within the range of
Stephens’ kangaroo rat.
We specified grazing as a significant
rangewide threat to Stephens’ kangaroo
rat in the 1988 final listing rule (53 FR
38465). Since then, there has been a
reduction in large-scale commercial
grazing operations throughout the range
of the species. As such, the impacts of
grazing have been reduced across the
range of the species such that now we
do not consider grazing to be a
rangewide threat. In some cases,
moderate levels of grazing appear to be
beneficial to Stephens’ kangaroo rat
habitat by maintaining an open
vegetation structure, which is preferred
by the species.
Most areas currently occupied by
Stephens’ kangaroo rat are threatened by
habitat degradation from encroachment
of nonnative grasses or loss of habitat
due to the natural succession to more
shrub-dominated communities. Invasion
of nonnative grasses alter both the
structure and composition of Stephens’
kangaroo rat habitat by filling in open
spaces and excluding forbs. This is a
current and rangewide threat that is
addressed by existing conservation
plans (habitat conservation plans and
integrated natural resources
management plans) to manage for
nonnative grasses and to reduce impacts
to Stephens’ kangaroo rat to ameliorate
the effects on nonnative grasses. But, at
this point in time, these plans are not
managing sufficiently large areas to
counteract the threat.
OHV use, with its resultant habitat
degradation and loss, continues to be a
threat to Stephens’ kangaroo rat habitat.
OHVs have negatively impacted
Stephens’ kangaroo rat at Steele Peak,
Lake Mathews, and San Jacinto core
reserves, and efforts to curtail illegal
trespassing and other encroachments
have had limited success. Inadequate
boundary fencing and patrols around
the core reserves have been attributed to
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to minimize predation and ensure that
populations of Stephens’ kangaroo rat
on core reserves remain viable.
Currently, there is no active
management in place to eliminate or
reduce potential predation from feral or
domestic cats in western Riverside or
San Diego Counties. To our knowledge,
predation from feral or domestic cats is
not known to be a significant threat to
Stephens’ kangaroo rat populations in
San Diego County because the four
extant populations exist in rural areas
where feral or domestic cat densities are
likely very low.
Factor B. Overutilization for
Commercial, Recreational, Scientific, or
Educational Purposes
In the 1988 listing rule (53 FR 38465),
the Service did not identify threats from
overutilization. The petition did not
provide information regarding this
factor, and we do not have any new
information to indicate that
overutilization of any kind is a threat to
Stephens’ kangaroo rat now or in the
foreseeable future.
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limited funding (RCHCA 2008, p. 13).
OHV trespass on public and private
lands is a known to threaten Stephens’
kangaroo rat rangewide, but we do not
currently know the magnitude of this
threat.
Based on our review of the best
scientific and commercial information,
we conclude that Stephens’ kangaroo rat
habitat continues to be threatened by
habitat degradation from urban
development, nonnative species, and
OHVs now and in the foreseeable future
throughout the Stephens’ kangaroo rat’s
range.
Summary of Factor C
We did not identify disease as a threat
to Stephens’ kangaroo rat in the final
listing rule, nor did the petitioner
provide any new substantive
information. Based on our review of the
best available scientific and commercial
information, we found no evidence that
disease is now or will become in the
foreseeable future a threat to Stephens’
kangaroo rat. We consider predation by
feral and domestic cats to be a threat to
the Stephens’ kangaroo rat rangewide,
and in particular in western Riverside
County, now and in the foreseeable
future.
Factor C. Disease or Predation
The 1988 final listing rule (53 FR
38465) stated that populations
occupying fragmented habitat, such as
Stephens’ kangaroo rat, could be more
easily extirpated from unpredictable
natural catastrophes, such as disease
outbreaks (53 FR 38468). However, at
the time of listing, disease was not
identified as a threat to Stephens’
kangaroo rat, nor did the petition
provide any information regarding this
factor. We have no new information that
suggests disease is a threat or would
become a threat to the species in the
foreseeable future.
In the 1988 listing rule, we did not
find the threat from predation to be
significant. However, we did express
concern that predation of Stephens’
kangaroo rat from domestic and feral
cats on reserves adjacent to urban
neighborhoods could increase as a result
of urbanization (53 FR 38467).
Fragmentation of habitat likely
promotes higher levels of predation by
urban-associated animals (e.g., domestic
cats) as the interface between occupied
habitat and developed areas is
increased. In addition, domestic cat
densities along the boundaries of urban
and natural areas can be artificially high
where cat owners, by providing food,
elevate cat populations far beyond
carrying capacity (Crooks and Soule
1999, p. 565). Densities of domestic and
feral cats are likely high near several
core reserves near urban areas in
western Riverside County and may
require an active management approach
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Factor D. The Inadequacy of Existing
Regulatory Mechanisms
At the time of listing in 1988,
regulatory mechanisms that afforded
some protection for Stephens’ kangaroo
rat included: (1) California Endangered
Species Act (the species was listed by
California as threatened in 1971); (2)
California Environmental Quality Act;
(3) land acquisition and management by
Federal, State, or local agencies or by
private groups and organizations; and
(4) local laws and regulations (53 FR
38465).
In the 1988 listing rule (53 FR 38468),
we found that inadequate regulatory
mechanisms place Stephens’ kangaroo
rat at risk. The status of regulatory
mechanisms with an impact on
Stephens’ kangaroo rat has changed
significantly since listing, with the
addition of habitat conservation plans
and agreements that conserve habitat
occupied by Stephens’ kangaroo rat. The
petitioner asserts that, because of the
extensive habitat preservation by the
Riverside County Habitat Conservation
Agency, delisting the species is
warranted at this time. However, we
believe that while habitat conservation
plans provide significant species and
habitat protection towards the recovery
of the Stephens’ kangaroo rat,
significant threats remain that warrant
the species’ protection under the Act.
The State and Federal regulatory
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mechanisms that aid in the conservation
of the Stephens’ kangaroo rat are
described below.
State Protections
California Endangered Species Act
(CESA)
Under provisions of the CESA, the
California Fish and Game (CFG)
Commission listed the Stephens’
kangaroo rat as threatened in 1971.
CESA includes prohibitions forbidding
the ‘‘take’’ of Stephens’ kangaroo rat
(Chapter 1.5, Section 2080, CFG code).
However, sections 2081(b) and (c) of
CESA allow California Department of
Fish and Game (CDFG) to issue
incidental take permits for State-listed
endangered and threatened species if:
(1) The authorized take is incidental
to an otherwise lawful activity;
(2) The impacts of the authorized take
are minimized and fully mitigated;
(3) The measures required to
minimize and fully mitigate the impacts
of the authorized take are roughly
proportional in extent to the impact of
the taking on the species, maintain the
applicant’s objectives to the greatest
extent possible, and are capable of
successful implementation;
(4) Adequate funding is provided to
implement the required minimization
and mitigation measures and to monitor
compliance with and the effectiveness
of the measures; and
(5) Issuance of the permit will not
jeopardize the continued existence of a
State-listed species.
As a delisted species, Stephens’
kangaroo rat would continue to be
protected by the CESA which affords
protection at the State level for
endangered and threatened species.
California Environmental Quality Act
(CEQA)
CEQA is the principal statute
mandating environmental assessment of
projects in California. The purpose of
CEQA is to evaluate whether a proposed
project may have an adverse effect on
the environment and, if so, to determine
whether that effect can be reduced or
eliminated by pursuing an alternative
course of action or through mitigation.
CEQA applies to projects proposed to be
undertaken or requiring approval by
State and local public agencies (https://
www.ceres.ca.gov/topic/env_law/ceqa/
summary.html). CEQA requires
disclosure of potential environmental
impacts and a determination of
‘‘significant effects’’ if a project has the
potential to reduce the number or
restrict the range of a rare or endangered
plant or animal; however, projects may
move forward if there is a statement of
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overriding consideration. If significant
effects are identified, the lead agency
has the option of requiring mitigation
through changes in the project or to
decide that overriding considerations
make mitigation infeasible (CEQA
section 21002). Protection of listed
species such as Stephens’ kangaroo rat
through CEQA is, therefore, dependent
upon the discretion of the lead agency
involved.
In the absence of its Federal status as
an endangered species, CEQA has the
potential to contribute to the protection
of Stephens’ kangaroo rat, but such
protection is not assured since lead
agencies are given discretion over
whether to require impact minimization
or mitigation measures. While CEQA
requires the consideration of effects to
Stephens’ kangaroo rat and whether
those effects can be reduced or
eliminated, projects that adversely affect
Stephens’ kangaroo rat may still move
forward. CEQA does not provide an
adequate regulatory mechanism in the
absence of listing under the Act to
ensure effects to Stephens’ kangaroo rat
and its suitable or occupied habitat are
avoided, reduced, or eliminated.
Natural Community Conservation Plans
(NCCPs)
The NCCP program is a cooperative
effort involving the State of California
and numerous private and public
partners to protect regional habitats and
species. The primary objective of NCCPs
is to conserve natural communities at
the ecosystem scale while
accommodating compatible land use,
including urban development (https://
www.dfg.ca.gov/habcon/). Natural
Community Conservation Plans help
identify and provide for the regional or
area-wide protection of plants, animals,
and their habitats, while allowing
compatible and appropriate economic
activity. Many NCCPs are developed in
conjunction with habitat conservation
plans prepared under the Act, including
the HCP and the MSCHP. The HCP and
the MSHCP are NCCP/habitat
conservation plans. If the Stephens’
kangaroo rat was delisted, the existing
NCCPs, and the protections they
provide, would remain in effect.
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Federal Protections
Endangered Species Act of 1973, as
Amended (Act)
Upon listing as endangered on
September 30, 1988 (53 FR 38465),
Stephens’ kangaroo rat received benefit
from the protections of the Act, which
includes the prohibition against take
and the requirement for interagency
consultation for Federal actions that
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may affect the species. Section 9 of the
Act prohibits the take of endangered
wildlife without special exemption. The
Service generally extends these
prohibitions through regulations for
threatened wildlife. The Act defines
‘‘take’’ as to harass, harm, pursue, hunt,
shoot, wound, kill, trap, capture, or
collect, or to attempt to engage in any
such conduct (16 U.S.C. 1532(19)). Our
regulations define ‘‘harm’’ to include
significant habitat modification or
degradation that results in death or
injury to listed species by significantly
impairing essential behavioral patterns,
including breeding, feeding, or
sheltering (50 CFR 17.3). Our
regulations also define ‘‘harass’’ as
intentional or negligent actions that
create the likelihood of injury to listed
species to such an extent as to
significantly disrupt normal behavior
patterns, which include, but are not
limited to, breeding, feeding, or
sheltering (50 CFR 17.3).
Section 7(a)(1) of the Act requires all
Federal agencies to utilize their
authorities in furtherance of the
purposes of the Act by carrying out
programs for the conservation of
endangered species and threatened
species. Section 7(a)(2) of the Act
requires Federal agencies to ensure that
any action they authorize, fund, or carry
out is not likely to jeopardize the
continued existence of listed species or
adversely modify their critical habitat.
Thus, listing the Stephens’ kangaroo rat
provided a variety of protections,
including the prohibition against take
and the conservation mandates of
section 7 for all Federal agencies. These
procedures and protections would not
be required if we delisted Stephens’
kangaroo rat, and significant reductions
in recovery effort and protection would
likely result. As a delisted species,
Stephens’ kangaroo rat would continue
to be protected by the Lacey Act (18
U.S.C. 42 et seq., and 16 U.S.C. 3371 et
seq.), which prohibits trade in wildlife
and plants that have been illegally
taken, possessed, transported, or sold.
Under section 10(a)(1)(B) of the Act,
the Service may issue ‘‘incidental take’’
(i.e., taking of endangered species that is
incidental to, but not the purpose of,
carrying out of an otherwise lawful
activity, 50 CFR 402.02) permits for
listed animal species to non-Federal
applicants, which provide exemptions
to the take prohibitions under section 9
of the Act. To qualify for an incidental
take permit, applicants must develop,
fund, and implement a Serviceapproved habitat conservation plan that,
among other requirements, details
measures to minimize and mitigate the
impact of such taking to listed species.
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Issuance of an incidental take permit by
the Service is subject to the provisions
of section 7 of the Act; thus, the Service
is required to ensure that the actions to
be covered by the habitat conservation
plan are not likely to jeopardize the
species or result in the destruction or
adverse modification of critical habitat.
As discussed under the Factor A
discussion, there are two existing
incidental take permits for Stephens’
kangaroo rat. If the Stephens’ kangaroo
rat was delisted, the existing HCPs, and
the protections they provide, would
remain in effect. The HCP and the
MSHCP are discussed below.
HCP (Western Riverside County)
The development of the Riverside
County Habitat Conservation Agency’s
Habitat Conservation Plan for the
Stephens’ Kangaroo Rat in Western
Riverside County (the HCP) was in
response to the threat of habitat loss due
to rapid urban and agricultural
development in western Riverside
County. The boundaries of the HCP
encompass an area of approximately
216,084 ha (533,954 ac) located within
western Riverside County and bordered
on the north by the San Bernardino
County line and on the south by the San
Diego County line. The area is generally
defined as territory west of the San
Jacinto Mountains with National Forest
Lands flanking the western and eastern
boundaries (Cleveland and San
Bernardino National Forests,
respectively) (RCHCA 1996, p. 31). Core
reserve areas are not protected in
perpetuity under the HCP; however, the
core reserves will be protected through
the term of the permit, which expires in
2026. When the HCP’s initial 30-year
term expires in 2026, the permittees
have expressed their intention to
process an amendment to the MSHCP to
allow coverage for the Stephens’
kangaroo rat throughout the MSHCP’s
area. Additionally, the HCP’s core
reserves are included within the
Conservation Area under the MSHCP.
Therefore, we anticipate a continued
conservation benefit to the species even
after the HCP expires. The primary
threat identified in the 1988 listing rule,
habitat destruction from urban and
agricultural development resulting in
isolated habitat patches has been largely
ameliorated or addressed in Riverside
County through the creation of the core
reserve system and the implementation
of the overarching habitat conservation
plans.
MSHCP (Western Riverside County)
The Western Riverside County
Multiple Species Habitat Conservation
Plan (MSHCP) contains species-specific
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objectives for Stephens’ kangaroo rat
that augment the core reserve design
system set forth in the HCP, which was
the key document intended for the longterm conservation strategy for the
Stephens’ kangaroo rat. Incidental take
of Stephens’ kangaroo rat had already
been permitted consistent with the HCP
within the HCP boundary (or fee area).
Additional terms and conditions within
the MSHCP Conservation Area set forth
three Objectives including: conservation
of an additional 1,214 ha (3,000 ac) of
Stephens’ kangaroo rat occupied habitat,
and that 30 percent of the total occupied
habitat conserved within the MSHCP
and HCP’s areas would be maintained at
a population of medium or higher
density (i.e., 5 to 10 individuals per
hectare) with no single core area
accounting for more than 30 percent of
the conservation target (WRCMSHCP
2003, p. M–198). Recent scientific data
indicates that these species-specific
objectives may have not been met in
terms of density or occupancy estimates
either within the minimum two Core
Areas outside the existing HCP
boundary (WRMSHCP 2009, pp. 18–20),
or, as previously discussed, within the
HCP plan area (HCP core reserves), as
no reliable density estimates are
available to date. Until the speciesspecific objectives are met within the
MSHCP plan area, threats due to habitat
loss and fragmentation remain.
Furthermore, while these threats are
largely ameliorated within the plan
boundary, the MSHCP is inadequate to
address these threats rangewide.
Sikes Act
The Sikes Act (16 U.S.C. 670a)
authorizes the Secretary of Defense to
develop cooperative plans for
conservation and rehabilitation
programs, and to establish outdoor
recreation facilities on military
installations. The Sikes Act also
provides for the Secretaries of
Agriculture and the Interior to develop
cooperative plans for conservation and
rehabilitation programs (INRMPs,
described below) on public lands under
their jurisdiction. While the Sikes Act of
1960 was in effect at the time of the
Stephens’ kangaroo rat’s 1988 listing, it
was not until the Sikes Act’s 1997
amendment (Sikes Act Improvement
Act) that Department of Defense (DOD)
installations were required to prepare
integrated natural resources
management plans (INRMPs).
Consistent with the use of military
installations to ensure the readiness of
the Armed Forces, INRMPs provide for
the conservation and rehabilitation of
natural resources on military lands.
They incorporate, to the maximum
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extent practicable, ecosystem
management principles and provide the
landscape necessary to sustain military
land uses. While the implementation of
INRMPs is subject to funding
availability, they address the
conservation of natural resources on
military lands and can be an added
conservation tool in promoting the
recovery of endangered and threatened
species, and other fish and wildlife
resources, present on military lands.
The U.S. Marine Corps and the U.S.
Navy have contributed to recovery
efforts for Stephens’ kangaroo rat on
military lands in San Diego County
through management and monitoring of
Stephens’ kangaroo rat populations. The
Stephens’ kangaroo rat populations at
MCBCP and NWSSB Detachment
Fallbrook are addressed under existing
INRMPs and specific management and
monitoring of these populations is a
reasonable expectation; however, there
is concern that Stephens’ kangaroo rat
occupied habitat may be reduced to less
than one-third of the habitat identified
in our baseline analysis (see Factor A
discussion above). If the Stephens’
kangaroo rat were no longer listed under
the Act, we would expect management
actions specific to maintaining
Stephens’ kangaroo rat populations at
Camp Pendleton and Detachment
Fallbrook to receive lower priority
within their respective INRMPs.
Although these INRMPs would likely
continue to provide a benefit to the
Stephens’ kangaroo rat through the
protection and management of habitat,
these benefits would be subject to
military funding allocations that
generally give higher priority to
management issues for endangered and
threatened species (U.S. Marine Corps
2007, pp. 1–3).
National Environmental Policy Act
(NEPA)
NEPA (42 U.S.C. 4321 et seq.) requires
all Federal agencies to formally
document, consider, and publicly
disclose the environmental impacts of
major Federal actions and management
decisions significantly affecting the
human environment, including natural
resources. NEPA documentation is
provided in an environmental impact
statement, an environmental
assessment, or a categorical exclusion,
and may be subject to administrative or
judicial appeal. In cases where that
analysis reveals significant
environmental effects, the Federal
agency must propose mitigation
alternatives that would offset those
effects (40 CFR 1502.14 and 1502.16).
These mitigations usually provide some
protection for listed species. However,
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NEPA does not require that adverse
impacts be fully mitigated, only that
impacts be assessed and the analysis
disclosed to the public.
Summary of Factor D
Although various State and Federal
laws provide some protection for
Stephens’ kangaroo rat and its habitat,
the Act is currently the primary law
providing protection for Stephens’
kangaroo rat since its listing as a
federally endangered species in 1988.
Existing regulatory mechanisms have
not protected the species from further
losses of populations and habitat.
The primary tool for conserving the
species has been the 1996 Riverside
County Habitat Conservation Agency’s
Habitat Conservation Plan for the
Stephens’ Kangaroo Rat in Western
Riverside County (the HCP); however,
the monitoring and management
protocols and practices are incomplete.
The 2004 Western Riverside County
Multiple Species Habitat Conservation
Plan (MSHCP) has the potential to
enhance the long-term persistence of
Stephens’ kangaroo rat within western
Riverside County, but as a multi-species
plan, it has dynamic conservation
objectives and priorities, and in terms of
the provisions addressing Stephens’
kangaroo rat, the MSHCP has not been
fully implemented at this time. The San
Diego North County MSCP is still in
draft form, and therefore assures no
protection to the species at this time.
On military lands, integrated natural
resources management plans (INRMPs)
address the conservation of natural
resources, including Stephens’ kangaroo
rat, and can be an added conservation
tool in promoting the recovery of the
species. Management practices under
active INRMPs do provide guiding
principles for preserving Stephens’
kangaroo rat and its habitat while
sustaining necessary military land uses.
In spite of the existing regulatory
mechanisms, Stephens’ kangaroo rat
continues to be impacted by habitat
modification and fragmentation due to
urban and agricultural development,
nonnative species, off-highway vehicles
(OHVs), and the potential impacts
associated with climate change. Current
threats may be reduced or eliminated to
insignificance through implementation
of habitat conservation plans when
appropriate adaptive management
procedures are fully implemented. In
summary, we conclude that significant
rangewide threats remain and, absent
the protections of the Act, the existing
regulatory mechanisms (CEQA, CESA,
NCCP, and NEPA) do not provide
sufficient protections to provide for the
long-term persistence of Stephens’
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kangaroo rat now and in the foreseeable
future.
Factor E. Other Natural or Manmade
Factors Affecting the Species’ Continued
Existence
At listing, habitat for Stephens’
kangaroo rat was severely reduced and
fragmented by development and related
activities in western Riverside County
(53 FR 38467, September 30, 1988). At
that time, we identified the following as
Factor E threats: Nonnative grass
succession (now discussed under Factor
A, above), use of rodenticides, reduction
in habitat size (now discussed as
fragmentation under Factor A, above),
and increased vulnerability to
unpredictable catastrophic events due to
small population size. After the 1988
listing, we identified climate change as
a new threat to the species. Current
Factor E threats impacting Stephens’
kangaroo rat include rodenticides, small
population size, and impacts of climate
change.
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Rodenticides
Pocket gophers (Thomomys bottae),
California ground squirrels
(Spermophilus beecheyi), and nonnative
rodents are sometimes considered
nuisance species on public and private
lands. These species are sometimes
targeted for control through use of
anticoagulant rodenticides. Stephens’
kangaroo rats use burrow networks of
pocket gopher (Thomomys bottae) and
California ground squirrels
(Spermophilus beecheyi) (Michael
Brandman Associates 1989, p. 7), and
are thus at risk of being unintentionally
poisoned by anticoagulant rodenticides
meant to target nuisance species.
Baits containing anticoagulants are
placed in and around burrows and may
also be consumed by nontarget species,
including Stephens’ kangaroo rats. Use
of rodenticides may have affected
Stephens’ kangaroo rat at State
recreation areas that had rodent control
programs and possibly at other locations
where known Stephens’ kangaroo rat
populations have inexplicably
disappeared. Direct ingestion of
rodenticides at bait stations by
Stephens’ kangaroo rats can be
ameliorated in part from the use of
elevated bait stations (Whisson 1999, p.
176), and the baiting of traps during
daylight hours when kangaroo rats are
inactive. However, poison bait that falls
to the ground or that is cached at ground
level by targeted species still poses a
threat to Stephens’ kangaroo rat if
ingested during nocturnal foraging or
encountered in use of abandoned
burrows.
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To the best of our knowledge
California State Parks (California
Department of Parks and Recreation) no
longer use rodenticides for rodent
control within the Lake Perris State
Recreation Area (Kietzer 2010). While
we do not know the magnitude of the
threat of rodenticide exposure, we do
consider rodenticide use a rangewide
threat to the Stephens’ kangaroo rat as
the second-generation anticoagulants
(brodifacoum, bromadialone and
difethialone) are commonly used as
rodenticides targeting rats, mice, ground
squirrels and other rodents and are
found in many over-the-counter pest
control products (Erickson and Urban
2004, pp. ii, 1). Based on an evaluation
of the ecological risks associated with
the use of bait products containing
rodenticide active ingredients, the
Environmental Protection Agency (EPA)
is classifying many bait products as
restricted-use pesticides. This will limit
their use to certified applicators who
have had sufficient training to know
when and how to use the products to
reduce the risk of nontarget organism
exposure. EPA is also requiring
modified and tamper-resistant bait
stations, which are expected to reduce
overall nontarget wildlife exposures and
resulting adverse effects (Erickson and
Urban 2004). These risk reduction
measures should lower the potential for
exposure now and in the future in both
urban and rural areas adjacent to lands
where Stephens’ kangaroo rat overlaps
with nuisance species (e.g., at Lake
Perris Reserve and in Ramona
Grasslands) and near private
agricultural lands, such as orchards and
rangelands.
Small Geographic Range and Population
Size
The best available scientific data
suggest that Stephens’ kangaroo rat is
extant within a relatively restricted
range within western Riverside and
northern San Diego Counties. Small
geographic range has been identified as
the most important single indicator of
elevated extinction risk in mammals
(Purvis et al. 2000, p. 1949; Cardillo et
al. 2006, pp. 4157–4158; Cardillo et al.
2008, p. 1445). The inherent
vulnerability associated with small
geographic range is due to the fact that
a single localized threat, whether it is
manmade (e.g., development) or
environmental (e.g., increased and
intense precipitation), can potentially
impact the entire distribution of the
species, resulting in an increased
probability of extinction. Price and
Endo (1989, p. 299) and O’Farrell and
Uptain (1989, p. 5) verified that the
majority of remaining Stephens’
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kangaroo rat populations occur in small,
isolated areas (habitat patches) and are
fragmented from a wider historical
distribution.
Although fragmentation does not
necessarily lead to extinction of a
species within a habitat patch, small
populations in small habitat patches
have an increased likelihood of
extinction and are increasingly affected
by their surroundings (e.g., edge effects
such as physical effects differing at the
boundaries of a patch and the interior of
a patch) (Noss and Cooperrider 1994,
pp. 51–54). Isolation compounds risks
associated with small population size,
because it reduces the chance that
populations will naturally recover
through immigration of dispersing
individuals from nearby populations
(Hanski 1994, p. 132), as has been
documented for several Stephens’
kangaroo rat populations (O’Farrell and
Uptain 1989, p. 5; Shultz et al. 1991,
p. 12). Theoretical predictions and
empirical evidence indicate that smaller
populations such as are found with
Stephens’ kangaroo rat tend to have
higher mortality rates and reduced
reproductive output, leading to
demographic fluctuations and an
increased susceptibility to
environmental catastrophes (Lande
1988, pp. 1456–1458; Lacy 1997, p. 321;
Frankham et al. 2002, pp. 24, 32). Small
populations have a higher probability of
extinction than larger populations, as
their low abundance renders them
susceptible to inbreeding, losses of
genetic variability, and demographic
problems (Lande 1988, p. 1455).
While populations of Stephens’
kangaroo rat are small, we do not have
any information regarding genetic
fitness of any populations. A general
principle of conservation biology states
that a species’ long-term persistence is
dependent upon its capacity to adapt to
changes in environmental conditions,
competition, predation, disease risk,
and parasites. Maintenance of genetic
diversity helps to ensure that a species’
adaptive capabilities are maintained
(Caughley 1994, pp. 217–221; Frankham
and Ralls 1998, p. 441). Results of
previous studies regarding the genetic
variability within and between
populations of Stephens’ kangaroo rat
are conflicting, and further investigation
is required to better understand the
adaptive capabilities of Stephens’
kangaroo rat and its ability to persist.
Population viability models were
developed to recommend the minimum
viable population sizes for Stephens’
kangaroo rat needed to sustain the
species at a 95 percent probability
(Burke et al. 1991, p. 1). The model
developed by Burke et al. (1991, pp.
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27–28) is the most recent quantitative
assessment of Stephens’ kangaroo rat
population viability and provides
probabilities of Stephens’ kangaroo rat
persistence for intervals of 50 and 100
years. However, this model relies upon
the fundamental assumption that the
extent of suitable habitat at each site
will not decrease throughout the
duration of the 50- and 100-year
intervals, and precipitation was
modeled over 50-, 100-, and 200-year
timeframes based on precipitation
during the previous century. Given the
significant advances in climate change
science and the emerging threat of
changes of precipitation regimes due to
climate change, newer studies with a
refined methodology are needed to
determine an effective population size
for Stephens’ kangaroo rat.
Climate Change
Since the 1988 listing of Stephens’
kangaroo rat, ongoing, accelerated
climate change has been identified as a
potential threat to species and
ecosystems in the United States (IPCC
2007). The Intergovernmental Panel on
Climate Change (IPCC) concluded that
warming of the climate system is
unequivocal (IPCC 2007, p. 5). Current
climate change predictions for terrestrial
areas in the Northern Hemisphere
include warmer air temperatures, more
intense precipitation events, and
increased summer continental drying
(Field et al. 1999, pp. 2–3; IPCC 2007,
p. 9).
The general prediction for climate
change impacts suggest increased
frequency of extreme weather events
(i.e., heat waves, droughts, and floods)
(IPCC 2007). Stephens’ kangaroo rat may
respond well after increased
precipitation events in the short term,
because increased precipitation results
in more forbs for seed production.
However, if increased intensity of
precipitation events favor the increased
persistence or an expansion in
distribution of annual nonnative
grasses, which are less preferred by
Stephens’ kangaroo rat, then these
extreme weather events may negatively
affect the species and its habitat.
However, there is no substantive
information as to how the changes in
regional climate patterns (i.e., frequency
and intensity of precipitation) will affect
Stephens’ kangaroo rat or its habitat;
predictions are based on continentalscale general models (e.g., precipitation
estimates) that do not yet account for
localized consequences, including land
use and land cover change effects on
climate or other regional phenomena.
While we recognize that climate
change is an important issue with
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potential effects to listed species and
their habitats, we currently do not have
specific information to make meaningful
predictions regarding climate change
effects to the Stephens’ kangaroo rat or
its habitat.
Summary of Factor E
Impacts to Stephens’ kangaroo rat by
Factor E threats have changed little
since the species’ 1988 listing. Although
reduced, the threat from rodenticide use
remains rangewide. Small population
size continues to affect this species
throughout its range and exacerbates the
effects of other threats, making
Stephens’ kangaroo rat susceptible to
stochastic events. Although it is
uncertain how climate change will
affect Stephens’ kangaroo rat or its
habitat, modeling predictions suggest
more extreme weather events, which
could impact the extent of suitable
habitat or induce stresses on the species.
Therefore, based on our review of the
best available scientific and commercial
information, we find other natural or
manmade factors, including
rodenticides, impacts of climate change,
and small population size, threaten the
continued existence of the Stephens’
kangaroo rat now and in the foreseeable
future.
Finding
An assessment of the need for a
species’ protection under the Act is
based on threats to that species and the
regulatory mechanisms in place to
ameliorate impacts from these threats.
As required by the Act, we considered
the five factors in assessing whether the
Stephens’ kangaroo rat is endangered or
threatened throughout all or a
significant portion of its range. We
examined the best scientific and
commercial information available
regarding the past, present, and future
threats faced by the Stephens’ kangaroo
rat. We reviewed the May 1, 1995, and
February 25, 2002, petitions; comments
and information received after
publication of our 90-day finding (69 FR
21567, April 21, 2004); information
available in our files; and other
available published and unpublished
information. We also consulted with
recognized experts on Stephens’
kangaroo rat and its habitat and with
other Federal and State agencies.
In considering what factors might
constitute threats, we must look beyond
the mere exposure of the species to the
factor to determine whether the species
responds to the factor in a way that
causes actual impacts to the species. If
there is exposure to a factor, but no
response, or only a positive response,
that factor is not a threat. If there is
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exposure and the species responds
negatively, the factor may be a threat
and we then attempt to determine how
significant a threat it is. If the threat is
significant, it may drive or contribute to
the risk of extinction of the species such
that the species warrants listing as
endangered or threatened, as those
terms are defined by the Act. This does
not necessarily require empirical proof
of a threat. The combination of exposure
and some corroborating evidence of how
the species is likely impacted could
suffice. The mere identification of
factors that could impact a species
negatively is not sufficient to compel a
finding that listing is appropriate; we
require evidence that these factors are
operative threats that act on the species
to the point that the species meets the
definition of endangered or threatened
under the Act.
The primary threats identified in the
1988 listing rule (53 FR 38465), habitat
destruction from urban and agricultural
development resulting in isolated
habitat patches, has been largely
ameliorated through the implementation
and design of the core reserve system
(through the HCP), through ongoing
land acquisitions and easements, and
with other conservation plans and
efforts (MSHCP and INRMPs).
Significant areas of habitat have been
protected in western Riverside County
and San Diego Counties since the
species was listed. Populations in San
Diego County that are on privately held
lands may enhance the survival and
recovery of the species, including some
habitat under permanent conservation
supporting the Ramona Grasslands
population. The Stephens’ kangaroo rat
population at Camp Pendleton/
Detachment Fallbrook in San Diego
County is covered by active INRMPs
that include actions to provide for the
long-term conservation of the Stephens’
kangaroo rat on Federal military lands.
In spite of these conservation gains,
significant threats to Stephens’ kangaroo
rat in Riverside and San Diego Counties
remain. There has been loss,
fragmentation, and degradation of
Stephens’ kangaroo rat habitat in the
past, and we have identified
information indicating that Stephens’
kangaroo rat habitat continues to be
threatened by fragmentation and
degradation associated with urban
development (see Factor A) in western
Riverside and San Diego Counties. This
habitat degradation is associated with
the lack of boundary security at some of
the core reserves, which allows trespass,
OHV use, and trash dumping, and the
lack of appropriate management (such
as fire suppression) to prevent invasive
species or succession to shrub-
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dominated communities. Lands
currently or historically dedicated to
agricultural activities likely continue to
serve as a source of invasive, nonnative
plants. Encroachment of nonnative
grasses and succession to more shrubdominated communities threaten
Stephens’ kangaroo rat habitat
throughout the species’ range by filling
open spaces and reducing the presence
of forbs (Factor A).
While existing data are not adequate
to estimate population size, within the
existing core reserves in western
Riverside County or in San Diego
County, surveys indicate that the
amount of Stephens’ kangaroo rat
occupied habitat may be in decline in
localities within both counties. Latest
survey data indicate that Camp
Pendleton, Detachment Fallbrook, and
Lake Henshaw, in addition to previous
declines in habitat populations, may
have suffered declines in the amount of
Stephens’ kangaroo rat occupied habitat.
Predation (Factor C) and rodenticide
(Factor E) continue to threaten the
species and may contribute additively to
other threats affecting this species.
Existing regulatory mechanisms, absent
the protections of the Act, provide
insufficient certainty (Factor D) that
efforts needed to address long-term
conservation of the species will be
implemented or that they will be
effective in reducing the level of threats
to the Stephens’ kangaroo rat
throughout its range. Therefore, we find
that, in absence of the Act, the existing
regulatory mechanisms are not adequate
to conserve Stephens’ kangaroo rat
throughout its range in the foreseeable
future.
In conclusion, we have carefully
assessed the best scientific and
commercial information available
regarding the past, present, and future
threats faced by this species. Our review
of the information pertaining to the five
threat factors does not support a
conclusion that the threats have been
sufficiently removed or their
imminence, intensity, or magnitude
have been reduced to the extent that the
species no longer requires the
protections of the Act. Therefore, we
find the Stephens’ kangaroo rat is in
danger of extinction, or likely to become
so within the foreseeable future,
throughout all or a significant portion of
its range and does not warrant delisting
at this time.
We request that you submit any new
information concerning the status of, or
threats to, the Stephens’ kangaroo rat to
our Carlsbad Fish and Wildlife Office
(see ADDRESSES) whenever it becomes
available. New information will help us
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monitor the Stephens’ kangaroo rat and
encourage its conservation.
References Cited
A complete list of references cited in
this document is available on the
Internet at https://www.regulations.gov
and upon request from the Carlsbad
Fish and Wildlife Office (see
ADDRESSES).
Authors
The primary authors of this notice are
the staff members of the Carlsbad Fish
and Wildlife Office.
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: August 6, 2010.
Wendi Weber,
Acting Director, Fish and Wildlife Service.
[FR Doc. 2010–20518 Filed 8–18–10; 8:45 am]
BILLING CODE 4310–55–P
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS–R4–ES–2010–0057;
92220–1113–0000–C3]
RIN 1018–AX23
Endangered and Threatened Wildlife
and Plants; Establishment of a
Nonessential Experimental Population
of Endangered Whooping Cranes in
Southwestern Louisiana
Fish and Wildlife Service,
Interior.
ACTION: Proposed rule.
AGENCY:
We, the U.S. Fish and
Wildlife Service (Service), propose to
reintroduce whooping cranes (Grus
americana), a federally listed
endangered species, into habitat in its
historic range in southwestern
Louisiana with the intent to establish a
nonmigratory flock that lives and breeds
in the wetlands, marshes, and prairies
there. We propose to classify the flock
as a nonessential experimental
population (NEP) according to section
10(j) of the Endangered Species Act of
1973 (Act), as amended. Releases will be
within the historic breeding area in
southwestern Louisiana near White
Lake in Vermilion Parish. This proposed
rule provides a plan for establishing the
NEP and provides for allowable legal
incidental take of whooping cranes
within the defined NEP area. The
objectives of the reintroduction are to
advance recovery of the endangered
whooping crane. No conflicts are
SUMMARY:
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envisioned between the reintroduction
and any existing or anticipated Federal,
State, Tribal, local government, or
private actions such as oil/gas
exploration and extraction, aquacultural
practices, agricultural practices,
pesticide application, water
management, construction, recreation,
trapping, or hunting.
DATES: We request that you send us
comments on the proposed rule and the
draft environmental assessment by the
close of business on October 18, 2010,
or at the public hearings. We will hold
public informational open houses from
6 p.m. to 7 p.m., followed by public
hearings from 7 p.m. to 9 p.m., on
September 15 and 16, 2010, at the
locations within the proposed NEP area
identified in the ADDRESSES section.
ADDRESSES: Written comments: You may
submit comments on the proposed rule
by one of the following methods:
• Federal eRulemaking Portal: https://
www.regulations.gov. Search for Docket
No. FWS–R4–ES–2010–0057 and follow
the instructions for submitting
comments.
• U.S. mail or hand-delivery: Public
Comments Processing, Attn: FWS–R4–
ES–2010–0057; Division of Policy and
Directives Management; U.S. Fish and
Wildlife Service; 4401 N. Fairfax Drive,
Suite 222; Arlington, VA 22203.
We will post all information received
on the proposed rule on https://
www.regulations.gov. This generally
means that we will post any personal
information you provide us (see the
Public Comments Procedures section
below for more details).
You may submit comments on the
draft environmental assessment (EA) by
one of the following methods:
• E-mail to:
LouisianaCranesEA@fws.gov.
• U.S. mail or hand-delivery:
Lafayette Field Office, U.S. Fish and
Wildlife Service, 646 Cajundome
Boulevard, Suite 400, Lafayette, LA
70506.
Please see the draft EA for additional
information regarding commenting on
that document.
Copies of Documents: The proposed
rule and EA are available by the
following methods. In addition,
comments and materials we receive, as
well as supporting documentation used
in preparing this proposed rule, will be
available for public inspection:
(1) You can view them on https://
www.regulations.gov. In the Search
Documents box, enter FWS–R4–ES–
2010–0057, which is the docket number
for this rulemaking. Then, in the Search
panel on the left side of the screen,
select the type of documents you want
E:\FR\FM\19AUP1.SGM
19AUP1
]]>Agencies
[Federal Register Volume 75, Number 160 (Thursday, August 19, 2010)]
[Proposed Rules]
[Pages 51204-51223]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-20518]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R8-ES-2010-0052; 92220-1113-0000C5]
Endangered and Threatened Wildlife and Plants; 12-Month Finding
on a Petition To Remove the Stephens' Kangaroo Rat From the Federal
List of Endangered and Threatened Wildlife
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 remove the Stephens' kangaroo rat
(Dipodomys stephensi) from the Federal List of Endangered and
Threatened Wildlife under the Endangered Species Act of 1973, as
amended. After a review of the best available scientific and commercial
information, we find that delisting the Stephens' kangaroo rat is not
warranted at this time. However, we ask the public to submit to us any
new information that becomes available concerning the threats to the
Stephens' kangaroo rat or its habitat at any time. This information
will help us monitor and encourage the conservation of this species.
DATES: The finding announced in this document was made on August 19,
2010.
ADDRESSES: This finding is available on the Internet at https://www.regulations.gov at Docket Number FWS-R8-ES-2010-0052. 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, Carlsbad Fish and Wildlife Office, 6010
Hidden Valley Road, Carlsbad, CA 92011. Please submit any new
information, materials, comments, or questions concerning this finding
to the above street address.
FOR FURTHER INFORMATION CONTACT: Jim Bartel, Field Supervisor, Carlsbad
Fish and Wildlife Office (see ADDRESSES); by telephone at 760-431-9440;
or by facsimile at 760-431-9624. If you use a telecommunications device
for the deaf (TDD), please call the Federal Information Relay Service
(FIRS) at 800-877-8339.
SUPPLEMENTARY INFORMATION:
Background
Section 4(b)(3)(B) of the Endangered Species Act of 1973, as
amended (Act; 16 U.S.C. 1531 et seq.), requires that, for any petition
to revise the Federal List of Endangered and Threatened Wildlife and
Plants that contains substantial scientific or commercial information
that delisting the species may be warranted, we make a finding within
12 months of the date of receipt of the petition. In this finding, we
will determine that the petitioned action is: (1) Not warranted, (2)
warranted, or (3) 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 List 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 12-
month findings in the Federal Register.
Previous Federal Actions
We listed Stephens' kangaroo rat as endangered on September 30,
1988 (53 FR 38465). We published a draft recovery plan for the
Stephens' kangaroo rat on June 23, 1997 (62 FR 33799; Service 1997, pp.
1-71), but it has not been finalized. The draft recovery plan provides
recovery guidance and a benchmark for delisting the species (Service
1997, p. 53), consisting of:
(1) Establishment of a minimum of five reserves, one of which is
ecosystem-based, in western Riverside County, California, that
encompass at least 6,675 hectares (ha) (16,500 acres (ac)) of occupied
habitat that are permanently protected, funded, and managed; and
(2) Establishment of two ecosystem-based reserves in San Diego
County, California, one in the Western Conservation Planning Area and
one reserve in the Central Conservation Planning Area, which are
permanently protected, funded, and managed.
Neither criteria have been met at this time. Discussion of the
criteria and their applicability are discussed in the Recovery Planning
and Implementation section below.
On May 1, 1995, we received a first petition, dated April 26, 1995,
from the Riverside County Farm Bureau (RCFB) requesting that the
Stephens' kangaroo rat be removed from the Federal List of Endangered
and Threatened Wildlife (in other words, delisted) under the Act.
[[Page 51205]]
The petition included supporting information stating that there were
original data errors and that the assumptions used by the Service
resulted in underestimating the numbers and range of the species and
overestimating the amount of habitat lost. We acknowledged the receipt
of the petition in a letter to the RCFB, dated June 12, 1995. On August
13, 1997, the RCFB sent us an inquiry regarding the status of the
delisting petition and requesting clarification as to whether we had
the funds or staff to respond with a 90-day finding on the petition. We
sent a letter to the RCFB on August 26, 1997, stating that we were
unable to review the petition and publish our 90-day finding due to
limited resources. We also provided the RCFB with additional
information concerning our Listing Priority Guidance for Fiscal Year
1997.
On February 25, 2002, we received a second petition from Mr. Robert
Eli Perkins, without reference to his affiliation, dated February 22,
2002, to delist the Stephens' kangaroo rat. We sent a letter
acknowledging the receipt of the second petition to Mr. Perkins on
August 6, 2002. The second petition was nearly identical to the
petition submitted by the RCFB in 1995, in that the 2002 petition
provided the same information and requested the same action. We treated
the second petition as a re-submittal of the first petition rather than
a formal second petition.
On April 21, 2004, we announced our 90-day finding that the
petition presented substantial information to indicate that the
petitioned action may be warranted (69 FR 21567), and we initiated a
status review of Stephens' kangaroo rat under section 4(b)(3)(A) of the
Act. We also announced our intention to complete a 5-year review of the
status of the species as required under section 4(c)(2)(A) of the Act.
We requested scientific and commercial data and other information
regarding the status of and threats to Stephens' kangaroo rat.
The Riverside County Farm Bureau filed a complaint on December 14,
2009 (CV 09-09162 CBM (OPx)) citing our failure to publish a 12-month
finding on their petition to delist Stephens' kangaroo rat. We reached
a settlement agreement with the plaintiffs on May 7, 2010, in which we
agreed to submit to the Federal Register a 12-month finding on the
plaintiff's petition by July 30, 2010.
This notice constitutes the 12-month finding on the February 25,
2002, petition (which we treated as a re-submittal of the May 1, 1995,
petition) to delist the Stephens' kangaroo rat.
Species Information
Species Description and Taxonomy
Stephens' kangaroo rat (Dipodomys stephensi Merriam) is a small,
nocturnal mammal. Kangaroo rats are more closely related to squirrels
than mice or rats and constitute a distinct group of rodents belonging
to the family Heteromyidae. Kangaroo rats are burrow-dwelling, seed-
eating animals that inhabit arid and grassy habitats in western North
America. They are characterized by fur-lined, external cheek pouches
used for transporting seeds; large hind legs for rapid, bi-pedal,
saltatorial (leaping) locomotion; relatively small front legs; long
tails; and large heads.
Stephens' kangaroo rat was first described as Perodipus stephensi
based on a specimen collected near Winchester, Riverside County,
California (Merriam 1907, p. 78). As part of a major study of kangaroo
rats in California, Grinnell (1919, p. 203; 1922, p. 7) found no good
grounds for retaining the genus Perodipus. As a consequence of these
findings, Grinnell (1921, p. 95) published the currently recognized
name Dipodomys stephensi. The Integrated Taxonomic Information System
(ITIS 2010, TSN 180247) and more recent checklists continue to
recognize Dipodomys stephensi as a distinct species (Baker et al. 2003,
p. 13; Bisby et al. 2010).
Geographic Range and Status
Stephens' kangaroo rat typically occurs at lower elevations in flat
or gently rolling grasslands of the dry inland valleys west of the
Peninsular Ranges of southern California, in western Riverside and
northern and central San Diego Counties (Grinnell 1922, p. 67; Lackey
1967a, p. 315; Bleich 1973, p. 46; Bleich and Swartz 1974, pp. 208-210;
O'Farrell et al. 1986, pp. 187-189; O'Farrell and Uptain 1989, p. 1;
Pacific Southwest Biological Services, Inc. 1993, pp. 4-36; Ogden
Environmental and Energy Services Co, Inc. (Ogden) 1997, p. 3). This
historical range is small for rodents in general, and particularly for
kangaroo rats (Price and Endo 1989, p. 294). At the time of listing in
1988, the Stephens' kangaroo rat's geographic range was reported as
encompassing the Perris, San Jacinto, and Temecula Valleys in western
Riverside County (Temecula Valley was mistakenly reported as located in
San Diego County), and the San Luis Rey Valley in San Diego County (53
FR 38465). At listing, Stephens' kangaroo rat was known from 11 general
areas, and, currently, Stephens' kangaroo rat is found in 15 areas (see
Table 1 below).
Table 1--Geographical Areas of Known Stephens' Kangaroo Rat Populations
at Listing (1988) and at Present (2010)
------------------------------------------------------------------------
At listing At present
------------------------------------------------------------------------
Riverside County
------------------------------------------------------------------------
Kabian Park..................... known............. considered
nonviable.
������������������������������������������������������������������������
Lake Mathews/Estelle Mtn........ known............. extant.
Lake Skinner/Domenigoni Valley.. known............. extant.
Motte Rimrock................... known............. extant.
Potrero Valley.................. known............. extant.
San Jacinto/Lake Perris......... known............. extant.
Steele Peak..................... known............. extant.
Sycamore Canyon/March Air Force known............. extant, Sycamore
Base (AFB)*. Canyon portion
considered
nonviable.
Corona/Norco.................... unknown........... considered
nonviable.
Anza/Cahuilla (i.e., Silverado unknown........... extant.
Conservation Bank).
------------------------------------------------------------------------
San Diego County
------------------------------------------------------------------------
Lake Henshaw.................... known............. extant.
������������������������������������������������������������������������
[[Page 51206]]
Ramona Grasslands............... unknown........... extant.
Rancho Guejito.................. unknown........... extant.
MCBCP (Camp Pendleton).......... known............. extant.
Fallbrook....................... known............. extant.
------------------------------------------------------------------------
* The SKR Management Area on the former March AFB is not a reserve at
this time (2010).
Populations of Stephens' kangaroo rat continue to persist in areas
throughout the species' native range, despite fragmentation. Since
listing, additional populations have been found near Corona/Norco and
Anza/Cahuilla (i.e., Silverado Conservation Bank) in western Riverside
County, and Rancho Guejito and Ramona Grasslands in San Diego County,
extending distribution records to the northwest, east, and south of
areas known at the time of listing (Montgomery 1990, p. 3; Montgomery
1992, p. 3; Pacific Southwest Biological Services, Inc. 1993, pp. 4-39;
Ogden 1997, p. 11). Although discovered after listing, it is likely the
four additional populations were extant at the time of listing and were
detected as a result of more focused surveys and consultations
subsequent to listing. The populations identified after 1988
(subsequent to our listing of the species) are located near the
periphery of the Stephens' kangaroo rat's known range at the time of
listing and are considered new records of occurrence and not a range
expansion of the Stephens' kangaroo rat.
To date, no rangewide assessment has been conducted to estimate the
population size and indices of abundances (e.g., minimum number alive
index for Stephens' kangaroo rat across the species' range). Surveys
for Stephens' kangaroo rat necessary to derive useful population
estimates are difficult to conduct due to their nocturnal habits and
limited time above ground (see Biology section below). In fact, very
few studies have focused on the distribution of habitats and
populations throughout the animal's range (Thomas 1975, p. 1; O'Farrell
and Uptain 1989, p. 1), and much of the distributional information is
in the form of unpublished presence or absence survey reports at
particular sites from short-term live-trapping studies provided to
landowners or public agencies (Price and Endo 1989, p. 294). More
recent information has come from localized area-specific survey reports
such as from Anza/Cahuilla and Potrero Valleys (Western Riverside
Multiple Species Habitat Conservation Plan Biological Monitoring
Program, April 2009). Because live-trapping methodologies vary and
result in different capture probabilities, survey results across
studies are difficult to interpret in terms of population estimates.
However, such methodologies are useful for determining occupied habitat
and detecting changes in species distribution.
Suitable Stephens' kangaroo rat habitat has been mapped and
categorized using a variety of different classification schemes,
including categories such as occupied, potentially occupied, and
probably occupied. Although mapping of ``occupied'' habitat has been
the most common method used for assessing the status of Stephens'
kangaroo rat, it can be problematic, as not all areas have been mapped,
and most areas have not been mapped over time to obtain information
about trends in the extent of habitat occupied. More detailed and
consistent survey information is needed to determine useful accurate
and defensible estimates of populations and demographic trends for the
Stephens' kangaroo rat rangewide (Diffendorfer and Deutschman 2003, p.
6).
For this 12-month status review and finding, we identified all
areas occupied by Stephens' kangaroo rat at any point in time since the
species was listed in 1988. Characterizations of these areas form the
basis of our understanding of the known distribution of extant
occurrences of Stephens' kangaroo rat throughout its range. We refer to
these areas collectively as the ``baseline Stephens' kangaroo rat
occupied habitat'' throughout this finding. The total baseline
Stephens' kangaroo rat occupied habitat mapped for Riverside and San
Diego Counties is 22,221 ha (54,909 ac). We consider this to be the
most current and best available scientific information regarding the
known distribution of occurrences and habitat of Stephens' kangaroo rat
throughout the species' range. In the past, when conducting habitat and
mapping exercises we have used a 100-meter grid to delineate habitat.
Because of improved mapping techniques, for this baseline occupied
habitat exercise, we mapped the areas as accurately as possible by more
directly approximating the delineation of habitat areas rather than
using a 100-meter grid to map habitat areas. We also digitized current
data and information available to us from survey monitoring reports not
previously available. We acknowledge that, due to varied mapping
precision and accuracy, as well as data and resource constraints, there
may be discrepancies between this and previous habitat acreage
assessments.
Biology
Stephens' kangaroo rat constructs burrows to serve as sleeping
quarters and nesting sites (Bleich 1973, p. 73). Burrows of Stephens'
kangaroo rat are frequently found clustered in burrow complexes (Brock
and Kelt 2004, p. 52). Burrow depths range between 23 and 46
centimeters (cm) (9 and 18 inches (in)), and multiple burrow openings
may be adjoined. Burrow complexes consist of a network of tunnels
connecting multiple entrances (Thomas 1975, p. 38; O'Farrell 1990, p.
78), with tunnel pathways corresponding to surface runways (O'Farrell
and Uptain, 1987, p. 34). Individuals typically emerge from their
burrows after sunset; they may be active at any time of night. However,
O'Farrell (pers. comm. 1986) has observed that Stephens' kangaroo rats
spend very little time (less than 1 hour) above ground each day and,
when they are above ground, they move quickly between points.
Kangaroo rats, including Stephens' kangaroo rat, are primarily
granivores (seed-eaters) and when above ground, spend most of their
time moving about the surface, alternating between periods of
locomotion with stops to extract seeds. Seeds are extracted from the
soil by digging with their forefeet and balancing on their hind legs
(Reichman and Price 1993, p. 541), by direct clipping of seed stalks
and extracting seeds from the felled seed heads of fruit (Reichman and
Price 1993, p. 542), or by harvesting seeds directly from fruit that
lie within 15 to 20 cm (5.9 to 7.9 in) of the ground (Reichman and
Price 1993, p. 543). Stephens' kangaroo rats often store large
quantities of seeds, which they initially collect in their external
cheek pouches and then transfer and
[[Page 51207]]
bury in burrows or surface caches for later consumption (Reichman and
Price 1993, p. 543; Goldingay et al. 1997, p. 49). Seed caching may
enable species of Dipodomys to survive during temporary shortages of
food (Reichman and Price 1993, p. 543) or extreme seasonal fluctuations
in food availability (Morgan and Price 1992, p. 2260). Although seeds
are their primary food source, green vegetation and insects appear to
be important seasonal food and water sources (Reichman and Price 1993,
p. 540). Surface activity for Stephens' kangaroo rat changes through
the year, reflecting seasonal rainfall and subsequent vegetative
productivity (O'Farrell and Clark, 1987, p. 10). Previous studies on
Stephens' kangaroo rat indicate that late spring to early summer
breeding results in peak population recruitment in August (Lackey
1967b, p. 625; Bleich 1977, p. 1; O'Farrell and Clark 1987, p. 11).
The average litter size for the Stephens' kangaroo rat ranges from
2.7 to 2.8 individuals (Lackey 1967b, p. 625; Price and Kelly 1994, p.
815). The timing of breeding for Stephens' kangaroo rat is highly
variable, with reproduction likely triggered by the growth of
vegetation subsequent to winter rain (McClenaghan and Taylor 1993, pp.
642-643; Price and Kelly 1994, p. 813). Studies on Stephens' kangaroo
rat indicate a late spring to early summer breeding season (Bleich
1977, p. 1; McClenaghan and Taylor, p. 636), although females on
occasion may remain reproductive until late fall as long as food
resources are adequate (McClenaghan and Taylor 1993, pp. 642-643; Price
and Kelly 1994, p. 813). Observations suggest the possibility for
multiple litters during favorable conditions (O'Farrell and Clark 1987,
p. 11).
Studies have estimated average Stephens' kangaroo rat survivorship
in the wild to be between 4.5 to 6.6 months, with some individuals
living for as long as 19 months (McClenaghan and Taylor 1991, p. 12;
Price and Kelly 1994, p. 815). However, these estimates are probably
low due to the limited timeframe of the studies and the inability to
distinguish between actual mortality and emigration. Adults appear to
have higher survival rates than subadults.
Home ranges for Stephens' kangaroo rat vary according to physical
habitat features, season, food availability, population density, and
gender. Efforts to characterize the home range size or movements of
Stephens' kangaroo rat have primarily relied on live trapping (Thomas
1975, p. 7), or a combination of live trapping and radio telemetry, to
characterize movement patterns (Kelly and Price 1992, p. 4; Price et
al. 1994b, p. 931). Estimates for mean home ranges within a population
vary between 0.02 and 0.13 ha (0.05 and 0.32 ac) (Thomas 1975, p. 49;
Kelly and Price 1992, pp. 19-20). Home ranges generated from live-
trapping data are likely to be underestimates for this species (Kelly
and Price 1992, p. 12), because the presence of live traps likely
changes how the Stephens' kangaroo rat moves within its home range.
Stephens' kangaroo rat is generally considered highly sedentary
(Price et al. 1994b, p. 935), but in one instance, Price et al. (1994b,
pp. 933-935) recorded an individual moving over 1.0 km (0.6 mi) between
trapping grids. The median maximum distance moved by Stephens' kangaroo
rat individuals between capture sites was within 29 m (96 ft) of the
initial point of capture, with 18 m (58 ft) as the median distance
moved between the first and last monthly home-range center (for
individuals captured in 2 or more months). Juveniles and adults were
found to maintain a home-range center of 30 m (98 ft) (Price et al.
1994b, p. 935). Males are more mobile than females, and lactating
females are especially sedentary; dispersal distances are similar for
adults and juveniles. O'Farrell (1993, p. 12) found that 40 percent of
the population was mobile at any one time and, in contrast to Price et
al. (1994b, pp. 933-935), observed some movements in excess of 396 m
(1,300 ft) (O'Farrell 1993, p. 66). Dispersal distances are usually
less than 500 m (1,641 ft) (Price et al. 1994, p. 936).
Habitat and Ecosystem
General habitat conditions for Stephens' kangaroo rat are described
in the literature (Bleich 1977, p. 8; Lackey 1967, p. 331; Price et al.
1991, p. 180; Goldingay and Price 1997, p. 715; Service 1997, pp. 9-
11). Studies have variously characterized habitat occupied by this
species as ``sparse vegetation, level or rolling topography, and soil
that is neither extremely dense nor largely sand'' (Lackey 1967, p.
318) or as consisting of annual grasslands with sparse cover of
perennial shrubs (Price and Endo 1989, p. 294). The term ``grassland''
is a generalization of this species' preferred vegetation community;
the Stephens' kangaroo rat appears to have a higher affinity for
vegetation communities dominated by herbaceous plants (forbs) with a
low density of grasses than for a vegetation community dominated by
grasses (O'Farrell and Clark 1987, p. 10; O'Farrell and Uptain 1987, p.
9). Stephens' kangaroo rat prefers grassland communities dominated by
forbs rather than by annual grasses, as annual forbs provide critical
greens in the spring, furnish temporary cover, produce large seeds, and
rapidly disintegrate after drying, resulting in substantial patches of
bare ground (O'Farrell and Uptain 1989, p. 7; O'Farrell and Clark 1987,
p. 10) that provide suitable conditions for the species' specialized
mode of locomotion (Bartholomew and Caswell 1951).
Stephens' kangaroo rat reaches its highest densities in grassland
communities dominated by forbs and characterized by moderate to high
amounts of bare ground, moderate slopes, and well-drained soils
(O'Farrell and Uptain 1987, pp. 35, 36; O'Farrell 1990, p. 80; Anderson
and O'Farrell 2000, p. 12). Stephens' kangaroo rat has been found on 36
types of well-drained soils, and more than 125 soil types (Service
1996, p. 6) that are capable of supporting annual grasses mixed with
forbs and shrub species.
Genetics
Genetic variability within and between populations of Stephens'
kangaroo rat has been investigated based on allozyme (protein)
variation (McClenaghan and Truesdale 1991 pp. 5-6, McClenaghan 1994, p.
12) and through DNA analysis (Metcalf et al. 2001, p. 1239). Analysis
of allozyme variation indicates populations on Marine Corps Base Camp
Pendleton (MCBCP) in San Diego County are genetically similar to
populations in western Riverside County (McClenaghan 1994, p. 25). In
contrast, mitochondrial DNA analysis (mtDNA) of 16 populations across
the range of Stephens' kangaroo rat found a higher degree of genetic
differentiation (derived characteristics) between occupied locations
(Metcalf et al. 2001, p. 1239) than found by the above-referenced
allozyme studies. Metcalf et al.'s (2001, p. 1238) results infer that
gene flow might be restricted between three hypothesized regions of
potential differentiation: North (corresponds to northwestern and
northeastern Riverside County), central (corresponds to central western
Riverside County), and south (corresponds to north and central San
Diego County), and particularly between the south region and the north
and central regions. However, based on inconclusive sample sizes from
each population (2 to 5 individuals per population), geographic
restriction in gene flow advanced by Metcalf et al. (2001, p. 1241)
should be considered preliminary.
[[Page 51208]]
Recovery Planning and Implementation
Section 4(f) of the Act directs us to develop and implement
recovery plans for listed species. We published a draft recovery plan
for Stephens' kangaroo rat on June 23, 1997 (62 FR 33799) and requested
public comment on that draft plan for 60 days, ending August 22, 1997.
We have not yet prepared a final recovery plan.
Section 4(f) of the Act requires the Service to develop and
implement recovery plans for the conservation and survival of
endangered and threatened species, unless we find that such a plan will
not promote the conservation of the species. The Act directs that, to
the maximum extent practicable, we incorporate into each plan: (1)
Site-specific management actions that may be necessary to achieve the
plan's goals for conservation and survival of the species; (2)
objective, measurable criteria that, when met, would result in a
determination, in accordance with the provisions of section 4 of the
Act, that the species be removed from the list; and (3) estimates of
the time required and the cost to carry out the plan. However,
revisions to the List of Endangered and Threatened Wildlife (adding,
removing, or reclassifying a species) must reflect determinations made
in accordance with section 4(a)(1) and 4(b) of the Act. Section 4(a)(1)
of the Act requires that the Secretary determine whether a species is
endangered or threatened (or neither) because of one or more of five
threat factors. Therefore, recovery criteria must indicate when a
species is no longer endangered or threatened by the five factors. In
other words, objective, measurable criteria, or recovery criteria,
contained in recovery plans must indicate when an analysis of the five
threat factors under section 4(a)(1) of the Act would result in a
determination that a species is no longer endangered or threatened.
Section 4(b) requires the determination made under section 4(a)(1) as
to whether a species is endangered or threatened because of one or more
of the five factors be based on the best available scientific and
commercial data.
Thus, while recovery plans are intended to provide guidance to the
Service, States, and other partners on methods of minimizing threats to
listed species and on criteria that may be used to determine when
recovery is achieved, they are not regulatory documents and cannot
substitute for the determinations and promulgation of regulations
required under section 4(a)(1) of the Act. Determinations to remove a
species from the List of Endangered and Threatened Wildlife made under
section 4(a)(1) of the Act must be based on the best scientific and
commercial data available at the time of the determination, regardless
of whether that information differs from the recovery plan.
In the course of implementing conservation actions for a species,
new information is often gained that requires recovery efforts to be
modified accordingly. There are many paths to accomplishing recovery of
a species, and recovery may be achieved without all criteria being
fully met. For example, one or more criteria may have been exceeded
while other criteria may not have been accomplished. The Service may
judge, however, that, overall, the threats have been minimized
sufficiently, and the species is robust enough to reclassify the
species from endangered to threatened or perhaps delist the species. In
other cases, recovery opportunities may have been recognized that were
not known at the time the recovery plan was finalized. These
opportunities may be used instead of methods identified in the recovery
plan.
Information on the species may be learned that was not known at the
time the recovery plan was finalized. The new information may change
the extent that criteria need to be met for recognizing recovery of the
species. Overall, recovery of species is a dynamic process requiring
adaptive management, planning, implementing, and evaluating the degree
of recovery of a species that may, or may not, fully follow the
guidance provided in a recovery plan.
Thus, while the recovery plan provides important guidance on the
direction and strategy for recovery, and indicates when a rulemaking
process may be initiated, the determination to remove a species from
the List of Endangered and Threatened Wildlife is ultimately based on
an analysis of whether a species is no longer endangered or threatened.
The following discussion provides a brief review of recovery planning
for Stephens' kangaroo rat, as well as an analysis of the recovery
criteria and goals as they relate to evaluating the status of the
species.
The draft recovery plan identified a proposed recovery strategy
based on the conservation of two types of reserves for the Stephens'
kangaroo rat:
(1) Ecosystem-based reserves that are not isolated from large
expanses of natural habitat and are anticipated to retain their
biological diversity, thus needing only low levels of management; and
(2) Non-ecosystem-based reserves that are biologically isolated for
the most part from large expanses of natural habitat and are
anticipated to lose biological diversity, thus needing high to
intensive levels of management.
The proposed recovery strategy recognized the importance of
conserving both types of reserves (i.e., sufficient habitat) to
maintain genetic and phenotypic diversity, to conserve representative
populations of the species, and to provide redundancy in conserved
populations to protect against catastrophic events that could extirpate
the species from a significant portion of its range (Service 1997, pp.
48-49; see Factor A, D, and E discussions below). While this strategy
for the conservation and recovery of Stephens' kangaroo rat is, in
concept, still applicable and reflective of the approach the Service
has used to guide conservation of Stephens' kangaroo rat, the recovery
criteria and objectives as outlined in the 1997 draft recovery plan
have not been revised to reflect information provided during public
comment or to incorporate new and updated information generated since
then. In addition, the goals and recovery criteria are ecosystem-based,
and, while this approach generally addresses threats to the species, it
does not provide explicit detail or guidance on determining whether
threats have been ameliorated. Because ecosystem-based recovery actions
are likely insufficiently detailed to address current and emerging
threats (see Factor A and E discussions below), especially given new
scientific information, this suggests the need to reevaluate the
recovery strategy and criteria for Stephens' kangaroo rat. In addition
to current conservation efforts, additional management approaches may
be needed to maintain sufficient habitat requirements for the species'
long-term survival. Further, the draft recovery plan's criteria do not
identify population or demographic goals that would indicate that
actions to ameliorate specific threats have been effective in ensuring
the persistence of Stephens' kangaroo rat throughout its range in the
foreseeable future. Despite the limitations discussed above, we
consider the draft recovery plan to serve as an important document that
sets out conservation goals for Stephens' kangaroo rat.
As discussed earlier, the 1997 draft recovery plan recommended the
following objectives and criteria for delisting the Stephens' kangaroo
rat (Service 1997, p. 53):
(1) Establishment of a minimum of five reserves, of which one is
ecosystem-based, in western Riverside County that
[[Page 51209]]
encompass at least 6,675 ha (16,500 ac) of occupied habitat that are
permanently protected, funded, and managed (refer to Western Riverside
County--Stephens' Kangaroo Rat Habitat Conservation Plan (HCP) under
Factor A below); and
(2) Establishment of two ecosystem-based reserves in San Diego
County, one in the Western Conservation Planning Area and one reserve
in the Central Conservation Planning Area, that are permanently
protected, funded, and managed (refer to San Diego County sections
under Factor A below).
The goal of Criterion 1, conserving at least 6,675 ha (16,500 ac),
is linked to addressing the primary threat of habitat loss through
urbanization. Criterion 2 is linked to threat of habitat loss and
fragmentation and deleterious effects of small population size for the
Stephens' kangaroo rat through conserving the geographic distribution,
and phenotypic and genetic diversity, of the species across its known
range.
Criterion 1
The primary objective identified in the draft recovery plan is to
protect and maintain sufficient populations and habitat of the
Stephens' kangaroo rat to allow the removal (delisting) of this species
from the Federal List of Threatened and Endangered Wildlife under the
Act (Service 1997, p. 52). At the time of listing, the primary threat
to the Stephens' kangaroo rat was direct habitat loss due to urban and
agricultural development. The goal of Criterion 1, conserving at least
6,675 ha (16,500 ac), is linked to addressing the primary threat of
habitat loss through urbanization. However, because smaller, more
isolated, non-ecosystem-based reserves were expected to be inherently
unstable due to their configurations and current or future isolation
from surrounding natural habitat due to the then existing or
anticipated development, they were expected to require intensive
management (Service 1997, p. 54). Additionally, establishing a minimum
of three ecosystem-based conservation units (Service 1997, p. 54), one
ecosystem-based conservation unit in western Riverside County
(Criterion 1) and two in San Diego County (Criterion 2, see below) was
thought appropriate to address the deleterious effects of diminishing
biological diversity associated with small, biologically isolated
reserves. Because western Riverside County was the area where Stephens'
kangaroo rat was most threatened by existing and future urbanization,
the maintenance of habitat quality and suitability there was considered
essential for the conservation of this species (Service 1997, p. 49).
Since drafting Criterion 1 in 1997, we have worked with private
landowners and local, State, and Federal partners to develop and
implement actions to reduce threats and provide for the long-term
conservation of the Stephens' kangaroo rat. The primary mechanism for
implementing recovery actions for the Stephens' kangaroo rat has been
through a regional habitat conservation plan in western Riverside
County called the Riverside County Habitat Conservation Agency's
Habitat Conservation Plan for the Stephens' Kangaroo Rat in Western
Riverside County (the HCP) (see Western Riverside County--Stephens'
Kangaroo Rat Habitat Conservation Plan (HCP) below). Through this
regional HCP (and other cooperative management agreements and
conservation plans), a Stephens' kangaroo rat core reserve system, plus
additional lands for the benefit of Stephens' kangaroo rat, is now
dedicated to the conservation of the Stephens' kangaroo rat in western
Riverside County.
Based on our analysis of baseline Stephens' kangaroo rat occupied
habitat within the western Riverside County HCP area (Service 2010; see
Table 2 below), the Stephens' kangaroo rat core reserves (not including
the Potrero Valley or March Air Force Base portion of the Sycamore
Canyon/March Air Force Base Reserve) encompass 4,971 ha (12,568 ac) of
baseline occupied habitat. Including Potrero Valley lands, 5,911 ha
(14,606 ac) is currently in conservation within western Riverside
County. Although management is required, Potrero Valley lands could
serve to meet the ecosystem-based reserve portion of this criterion.
These protected areas of baseline occupied habitat capture the
geographic distribution of Stephens' kangaroo rat within western
Riverside County. While the acquisition of lands in Stephens' kangaroo
rat core reserves has largely ameliorated the threats of habitat loss
due to urban development identified at the time of listing, Criterion 1
also specifies that these reserves be permanently protected, funded,
and managed to maintain habitat suitability and ensure the long-term
survival of Stephens' kangaroo rat. These components of Criterion 1
have yet to be fully implemented (see following discussion and Western
Riverside County--Stephens' Kangaroo Rat Habitat Conservation Plan
(HCP) section below).
Endowments for management of four of the core reserves (Lake
Mathews/Estelle Mountain, Lake Skinner/Domenigoni Valley, Motte
Rimrock, and Potrero Valley) and for Sycamore Canyon Wilderness Park
are provided either through the Metropolitan Water District of Southern
California, the HCP, or the Western Riverside County Multiple Species
Habitat Conservation Plan (MSHCP). The 1997 draft recovery plan
indicated intensive management of non-ecosystem-based reserves in
western Riverside County would be required, but the draft plan did not
identify specific goals or objectives to assess the effectiveness of
management and to evaluate the response of populations of Stephens'
kangaroo rat to management actions. As discussed under the Factor A
analysis below, recent surveys (dates range from 1991 to 2006) indicate
that the amount of occupied habitat on some of the Stephens' kangaroo
rat core reserves has decreased over time, and monitoring efforts are
not yet sufficient to determine Stephens' kangaroo rat population
trends within the 5,911 ha (14,606 ac) of conserved baseline occupied
habitat. This indicates that current management may not be effective
and that further monitoring is needed to evaluate the effectiveness of
ongoing conservation efforts. Therefore, we conclude that the primary
goal of Criterion 1 for delisting as described in the 1997 draft
recovery plan has not yet been fully met.
Criterion 2
Criterion 2 for delisting recommends the establishment of two
ecosystem-based reserves, one in western and one in central San Diego
County that are permanently protected, funded, and managed. The draft
recovery plan defines an ecosystem-based reserve as ``not isolated from
large expanses of natural habitat'' and needing ``only minimal
management due to the integrity of the natural system.''
Criterion 2, similar to Criterion 1, was meant to address the
threat of habitat loss to the Stephens' kangaroo rat and to conserve
the geographic distribution, and phenotypic and genetic diversity, of
the species. Criterion 2 is linked to the threat of habitat loss and
fragmentation and to the deleterious effects of small population size
for the Stephens' kangaroo rat through conserving the geographic
distribution, and phenotypic and genetic diversity, of the species
across its known range. Since the draft recovery plan was written,
additional populations have been discovered in Ramona Grasslands and
Rancho Guejito (see Geographic Range and Status section above).
Additionally, Criterion 2 was developed to guard against the
deleterious effects of diminishing biological diversity associated with
[[Page 51210]]
small, biologically isolated reserves (see Small Geographic Range and
Population Size under Factor E below) by establishing larger ecosystem-
based reserves.
The 1997 draft recovery plan did not, however, identify an acreage
requirement in its definition of an ecosystem-based reserve. Rather,
the draft plan indicated that ecosystem-based reserves should be
surrounded by large expanses of natural habitat, which would allow them
to retain their biological diversity and require only minimal
management to promote the relatively rapid recovery of Stephens'
kangaroo rat in the wild (Service 1997, p. 49). Based on our analysis
of baseline Stephens' kangaroo rat occupied habitat in San Diego County
(Service 2010), only populations of Stephens' kangaroo rat at Lake
Henshaw, at Rancho Guejito, or on Camp Pendleton and Detachment
Fallbrook are likely large enough or are surrounded by sufficient
natural habitat to meet this criterion, and currently none of these
areas are permanently protected and managed (see discussion under
Factor A below).
The Stephens' kangaroo rat occupied habitat and surrounding natural
lands on Camp Pendleton and Detachment Fallbrook may meet the intent of
the draft recovery plan for an ecosystem-based reserve in western San
Diego County. However, as discussed below under our Factor A analysis
below, most areas of known Stephens' kangaroo rat occupied habitat are
threatened by habitat degradation from encroachment of nonnative
grasses and succession to more shrub-dominated communities, and even
the largest Stephens' kangaroo rat populations may not be sustained
over the long term without high to intensive management. Thus, we
conclude that the criterion to establish ecosystem-based reserves that
are protected, funded, and managed within western or central San Diego
County has not been met.
Our review of the recovery criteria from the draft recovery plan
for Stephens' kangaroo rat indicates that while both types of reserves
have been established that help to ameliorate the threat of urban
development, the criteria have not been fully met because management
necessary to maintain habitat suitability is not yet in place. We also
conclude that while the criteria appropriately indicate the need for
habitat protection and intensive management of reserves, they are
outdated and no longer adequately address the current threats to the
species discussed below.
Summary of Information Pertaining to the Five Factors
Section 4 of the Act (16 U.S.C. 1533), and its implementing
regulations (50 CFR 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.
We must consider these same five factors in delisting a species. We
may delist a species according to 50 CFR 424.11(d) if the best
available scientific and commercial data indicate that the species is
neither endangered nor threatened for the following reasons:
(1) The species is extinct;
(2) The species has recovered and is no longer endangered or
threatened; or
(3) The original scientific data used at the time the species was
classified were in error.
In making this finding, information pertaining to the Stephens'
kangaroo rat 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 the petition we considered and evaluated the best available
scientific and commercial information.
The petition did not contain substantial information regarding the
biological status of Stephens' kangaroo rat or provide significant new
information as to current or future threats to the species.
Additionally, the petition did not provide a comprehensive review of
the status of the species or provide evidence suggesting that the
original listing was in error.
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
The 1988 listing rule identified widespread habitat loss and a
fragmented distribution of the species due to historical agriculture
practices and urban development as primary threats to the Stephens'
kangaroo rat (53 FR 38465, September 30, 1998). We considered urban and
agricultural development, grazing, and off-highway vehicles (OHVs) to
be significant and potentially rangewide threats to the long-term
persistence of Stephens' kangaroo rat at that time. These threats
continue for Stephens' kangaroo rat predominantly through habitat
modification and curtailment impacts, compared to direct habitat loss.
The 2002 petition did not present any significant new information
regarding the present or threatened destruction, modification, or
curtailment of habitat and range of the species.
Habitat Destruction and Modification by Urbanization and Land Use
Conversion
The habitat and range of Stephens' kangaroo rat has been reduced
over time. The species likely once occurred throughout annual grassland
or sparse coastal sage scrub communities of the Perris and San Jacinto
Valleys and up adjoining washes in southern California. As flat lands
were developed or converted into agriculture, the species likely became
isolated to low rolling hills and level ridge tops. With the arrival of
Spanish ranchers and agrarian practices (i.e., before 1938), native
perennial bunchgrass vegetation was replaced by annual grasslands and
ever since (i.e., in the later portion of the 20th century) has been
increasingly replaced by degraded annual grasslands (see Factor E
discussion below). Price and Endo's (1989, p. 299) study revealed that
the species suffered severe habitat loss and fragmentation throughout a
core area of its range over the past century, due primarily to
agricultural and urban development. In addition, O'Farrell and Uptain's
(1989, p. 5) assessment of the population and habitat status of the
Stephens' kangaroo rat throughout most of its range, which was
available just after the 1988 listing, corroborated the threats from
habitat loss and fragmentation to the species. They found that about 58
percent of previously known populations were extirpated due to human
development and that many of the extant populations remained only in
small and isolated areas. The petition asserted that we grossly over
exaggerated the amount of habitat lost. However, the petitioner did not
provide, and we do not possess, any new scientific or commercial data
indicating that our original estimates of habitat loss were
overestimations or were made in error.
In the 1988 final listing rule, we estimated the amount of suitable
habitat (but not necessarily occupied habitat) for the Stephens'
kangaroo rat prior to 20th-century agriculture was 124,775 ha (308,195
ac) in western Riverside County (53 FR 38467; Price and Endo
[[Page 51211]]
1989, p. 296). By 1984, the quantity of suitable habitat was reduced by
approximately 60 percent to 50,518 ha (124,779 ac) (Price and Endo
1989, p. 296; 53 FR 38467). No similar estimates of reduction of
suitable habitat for Stephens' kangaroo rat were available for San
Diego County at that time, but we surmise a roughly equivalent
magnitude of loss occurred concomitantly in San Diego County, given
land use conversion to agriculture in the early 20th century throughout
the grasslands of southern California.
Habitat modification and fragmentation involves both reduction in
size and increased isolation of habitats. Most extant populations of
Stephens' kangaroo rat were considered isolated from one another at the
time of the species' 1988 listing and that pattern of fragmentation has
been reinforced due to ongoing urbanization and land use conversions.
Occupied Stephens' kangaroo rat sites, especially in the western
portions of the range, have become increasingly isolated by surrounding
urban and agricultural development. In some cases, occupied sites may
be too fragmented to sustain viable populations of Stephens' kangaroo
rat (Burke et al. 1991, pp. 28-29), suggesting that conservation of
these smaller isolated populations may require enlarging patches of
suitable habitat or connecting patches via conservation corridors.
Similar to habitat loss, habitat fragmentation affects the persistence
of populations or a species within habitat fragments (Wilcove et al.
1986, pp. 237-238, 246-252; Morrison et al. 1992, pp. 43-47; Noss et
al. 1997, pp. 99-103; see Factor E discussion below).
Further, direct conversion of habitat by discing, burning, plowing,
and grading, and wildfire suppression fuel reduction activities
associated with human use and agricultural practices across the range
of the species, can result in habitat degradation of suitable and
occupied sites for Stephens' kangaroo rat. Deep discing may destroy the
burrows of Stephens' kangaroo rat and degrade remaining vegetation.
Although in some instances the open nature of plowed fields and farm
access roads has been shown to encourage occupancy by the Stephens'
kangaroo rat where fields are located near or adjacent to occupied
habitat, we have little additional information to evaluate the
potential frequency of reoccupation of abandoned agricultural lands or
persistence of populations on abandoned agricultural lands. Moore-Craig
(1984, p. 5) found that Stephens' kangaroo rats may recolonize a field
within 8 months after cessation of cultivation. Although the threat of
habitat loss and modification from agriculture land conversion was
considered less severe than the threat of habitat loss from
urbanization at the time of listing (because Stephens' kangaroo rats
were found to reinvade plowed fields if the agricultural usage was
abandoned (Thomas 1975, p. 46; 53 FR 38467)), the regularity and
persistence of these recolonization events by Stephens' kangaroo rat on
converted fields remains unknown. Information on the frequency of
reoccupation of abandoned agricultural lands, long-term persistence of
these populations on abandoned agricultural lands following a
recolonization event, or the persistence of these lands as occupied
habitat will require longer term and directed investigations.
Regardless, agricultural practices may still provide a persistent
source of nonnative vegetation and therefore remain an ongoing threat
to suitability of habitat for Stephens' kangaroo rat that warrants
future studies rangewide.
We estimated the baseline, from which to gauge recent impacts,
Stephens' kangaroo rat occupied habitat for Riverside and San Diego
Counties to be 22,221 ha (54,909 ac). Of that baseline, a total of 68
percent (15,059 ha/37,211 ac) is within Riverside County and 32 percent
(7,162 ha/17,698 ac) is in San Diego County. As of 2006, a total of
1,433 ha (3,537 ac) of baseline Stephens' kangaroo rat occupied habitat
was lost directly to development (see Table 2 below) in western
Riverside and San Diego Counties. Though 1,414 ha (3,492 ac) were
developed in Riverside County from 1984 to 2006 (Service 2010), impacts
from direct habitat loss to urban development have mostly been
ameliorated due to existing conservation efforts (see Recovery Planning
and Implementation above, and Factor A and D discussions). In San Diego
County, little baseline Stephens' kangaroo rat occupied habitat has
been developed (19 ha/46 ac), although the potential for impact due to
direct urban development remains high, especially if conservation
efforts are not guaranteed (see Factor A and D discussions). Relative
to previous discussions, it is important to note that not all baseline
Stephens' kangaroo rat occupied habitat (22,221 ha/54,909 ac) is still
currently occupied, and this represents only a small subset of the
estimated amount of suitable habitat (50,518 ha/124,779 ac) for
Stephens' kangaroo rat indicated in the 1988 listing rule.
Table 2--Amount of Stephens' Kangaroo Rat Habitat Occupied, Developed, and Conserved in Riverside and San Diego Counties
--------------------------------------------------------------------------------------------------------------------------------------------------------
BOH lost to
Location Total area ha (ac) BOH \1\ ha (ac) development ha BOH conserved ha
(ac) (ac)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Riverside County................................................. 1,890,263 (4,670,942) 15,059 (37,211) 1,414 (3,492) 6,275 (15,507)
Within the HCP \2\........................................... 223,470 (552,206) 12,568 (31,057) 1,071 (2,649) 4,971 (12,283)
Within MSHCP \3\............................................. 509,050 (1,257,889) 15,059 (37,211) 1,413 (3,492) \4\ 213 (526)
Potrero Valley............................................... 3,694 (9,128) 940 (2,323) 0 940 (2,323)
Johnson Ranch................................................ 272 (671) 1.9 (4.8) 0 1.9 (4.8)
Anza/Cahuilla............................................... 778 (1,922) 202 (500) 0 150 (370)
San Diego County................................................. 1,096,758 (2,710,148) 7,162 (17,698) 19 (46) 1,510 (3,932)
Lake Henshaw................................................ NA 4,331 (10,702) 2.5 (6.3) 0
Ramona...................................................... NA 67 (166) 0 67 (166)
Rancho Guejito.............................................. NA 1,224 (3,024) 0 0
Camp Pendleton.............................................. 50,692 (125,262) 422 (1,043) 0.1 (0.2) 422 (1,043)
Detachment Fallbrook........................................ 3,606 (8,910) 1,118 (2,762) 16 (39) 1,102 (2,722)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Baseline Stephen's kangaroo rat occupied habitat (BOH).
\2\ Western Riverside County Habitat Conservation Plan for the Stephens' Kangaroo Rat (HCP).
\3\ Western Riverside County Multiple Species Habitat Conservation Plan (MSHCP).
\4\ All lands under MSHCP, not just Additional Reserve Lands (ARL) lands.
[[Page 51212]]
Conservation Efforts
Several habitat conservation plans and other planning documents
have been developed and implemented in western Riverside and San Diego
Counties since 1988. These plans include: The Western Riverside County
Habitat Conservation Plan for the Stephens' Kangaroo Rat (the HCP) and
the Western Riverside County Multiple Species Habitat Conservation Plan
(MSHCP) in Riverside County, as well as the proposed San Diego North
County Multiple Species Conservation Plan (North County MSCP), Marine
Corps Base Camp Pendleton's (MCBCP) Integrated Natural Resources
Management Plan, and the Naval Weapons Station Seal Beach (NWSSB)
`Detachment Fallbrook' Integrated Natural Resources Management Plan,
all in San Diego County. Additional local conservation plans and
partnerships or active management agreements in both Counties are
ongoing within and outside the regional habitat conservation plans.
In western Riverside and San Diego Counties, existing conservation
planning efforts have slowed the rate of unregulated loss of habitat to
urban development and agricultural development. Currently, 36 percent,
or 7,882 ha (19,477 ac) of the total baseline Stephens' kangaroo rat
occupied habitat rangewide is conserved through regional habitat
conservation plans and conservation easements. Although the intensity
and magnitude of the threat from direct habitat loss for Stephens'
kangaroo rat has been greatly diminished through ongoing implementation
of habitat conservation plans and conservation processes in western
Riverside County, and to a lesser extent in San Diego County, both
habitat modification and curtailment are currently impacting the
species. In considering the limitations and inadequacies (see Factor D
discussion below) of ongoing efforts to implement or maintain adaptive
management practices (not specifically mandated by a habitat
conservation plan's terms and conditions), the duration and extent of
habitat degradation and decreasing habitat quality remains a rangewide
threat to the Stephens' kangaroo rat. Following is a discussion of the
regional plans in effect and what they provide and do not provide
regarding ongoing threats of habitat destruction and modification by
urbanization and land use conversion.
Western Riverside County--Stephens' Kangaroo Rat Habitat Conservation
Plan (HCP)
Since the 1988 listing of the Stephens' kangaroo rat, publicly
reviewed, regional habitat conservation planning under section
10(a)(1)(B) of the Act has guided recovery for the Stephens' kangaroo
rat, especially in western Riverside County. The HCP in western
Riverside County provides for protection of ``core reserves'' and
adaptive management of Stephens' kangaroo rat habitat in order to
ameliorate impacts to the species from habitat fragmentation and
degradation associated with development. The seven core reserves for
the Stephens' kangaroo rat were assembled from a combination of State
and federally owned lands, lands already in conservation (e.g., in open
space preserves or through conservation easements), lands acquired by
the Riverside County Habitat Conservation Agency (RCHCA), and other
cooperative partnerships (Table 3); Potrero Valley was added as a core
reserve on December 29, 2003, and March Air Force Base was removed
through an authorized land exchange (see Factor D discussion below).
Table 3--Area Conserved by Core Reserves Under the Stephens' Kangaroo Rat Habitat Conservation Plan (HCP) in
1996. Note: Potrero Valley Was Added to Core Reserve Desigh Later and Is Not Included in Total at Designation in
1996; 270 ha (667 ac) of Sycamore Canyon Remains in Conservation But Is Considered Nonviable
----------------------------------------------------------------------------------------------------------------
HCP Core Reserve In hectares In acres
----------------------------------------------------------------------------------------------------------------
Lake Skinner/Domenigoni Valley......... 5,325.............................. 13,158.
Lake Mathews/Estelle Mountain.......... 4,550.............................. 11,243.
San Jacinto/Lake Perris................ 4,424.............................. 10,932.
Sycamore Canyon/March Air Force Base... 1,013.............................. 2,502.
Steele Peak............................ 709................................ 1,753.
Potrero Area of Critical Environmental 403................................ 995.
Concern (ACEC).
Motte Rimrock Reserve.................. 258................................ 638.
[Potrero Valley Reserve]............... [approx 3,694]..................... [approx 9,128].
------------------------------------------------------------------------
Total at designation in 1996....... 16,682............................. 41,221.
----------------------------------------------------------------------------------------------------------------
Initiated with the ``Short-Term'' HCP in 1990, and continued with
the approval in 1996 of the ``Long-Term'' HCP (which is the document we
refer to as the HCP in this finding), the HCP was primarily envisioned
to address the need to minimize loss of known occupied Stephens'
kangaroo habitat in key localities (identified as ``Study Areas'' in
the Short-Term HCP) and implemented as the seven core reserves in 1996.
On May 2, 1996, we completed an intra-agency biological opinion and
issued an Incidental Take Permit for a 30-year term for the HCP under
section 10(a)(1)(B) of the Act. The HCP required the conservation of
6,070 hectares (15,000 ac) of Stephens' kangaroo rat occupied habitat
in seven core reserves within the 216,083-ha (533,954-ac) plan area and
authorized, under section 10(a)(1)(B) of the Act, the loss of all of
the remaining occupied Stephens' kangaroo rat habitat for development
(6,070 hectares (15,000 acres)) (RCHCA 1996, p. S-6). The Western
Riverside County Habitat Conservation Agency (RCHCA), along with eight
member jurisdictions (Cities of Corona, Hemet, Lake Elsinore, Moreno
Valley, Murrieta, Perris, Riverside, and Temecula), and unincorporated
areas within the plan, are permittees.
Near the time of permit issuance, the HCP core reserve boundaries
(i.e., within the conserved 16,682 ha/41,221 ac) included 5,042 ha
(12,460 ac) of Stephens' kangaroo rat occupied habitat, as reported by
RCHCA (1996, p. S-9). In a biological opinion dated May 2, 1996, it was
estimated that 11,307 acres of occupied Stephens' kangaroo rat occupied
habitat fell within the seven core reserve boundaries. There is no
dataset currently available to reliably quantify occupied habitat for
Stephens' kangaroo rat within the core reserves; RCHCA, after years of
incomplete monitoring efforts, developed a reserve-wide monitoring
protocol in July 2006,
[[Page 51213]]
but it was suspended in 2007 (RCHCA 2007, p. 12). A newly revised
monitoring protocol has been developed and is currently being
implemented in four of the reserves in 2010 (Lake Skinner/Domenigoni
Valley, Potrero Valley, Potrero ACEC, and San Jacinto/Lake Perris);
adoption of the monitoring protocol is anticipated on the other core
reserves in 2011 (Lake Mathews, Steele Peak, Motte Rimrock, and at
Sycamore Canyon Wilderness Park) (Gail Barton pers. comm., May 2010).
The largest four core reserves (L
