[Federal Register: August 19, 2010 (Volume 75, Number 160)]
[Proposed Rules]
[Page 51204-51223]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr19au10-19]
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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 http://
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.
いいいいいいいいいいいいいいいいいいいいいいいいいいいいいいいいいいいい
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.
いいいいいいいいいいいいいいいいいいいいいいいいいいいいいいいいいいいい
[[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 (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 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 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 long-term 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, multi-jurisdictional 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
[[Page 51214]]
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
(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 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 large-scale 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
[[Page 51215]]
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 species-specific 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 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 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, off-highway 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
[[Page 51216]]
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.
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
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 re-initiated 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 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
[[Page 51217]]
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-grass-dominated grasslands, less suited to Stephens' kangaroo
rat, have occurred throughout the species' range. Current and future
active management may be required to maintain suitable forb-dominated
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.
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 ground-dwelling 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 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
[[Page 51218]]
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.
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.
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 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.
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 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
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 (http://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
[[Page 51219]]
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 (http://
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.
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 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 Service-
approved habitat conservation plan that, among other requirements,
details measures to minimize and mitigate the impact of such taking to
listed species. 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
[[Page 51220]]
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 long-term 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 species-specific
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 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, 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'
[[Page 51221]]
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.
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.
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' 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.
[[Page 51222]]
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 continental-scale 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
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 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-
[[Page 51223]]
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 shrub-dominated 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 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 http://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