General Distribution
Stephens' kangaroo rat is known from arid grassland habitats in northern San Diego County, western
Riverside County, and along the southwestern edge of San Bernardino County (Bleich 1977). The
known range of the species has expanded since the 1977 species account by Bleich. Known populations
occur at Camp Pendleton Marine Corps Base, the adjacent Fallbrook Naval Weapons Station, around
Lake Henshaw/Warner Springs, in the Guejito, Ramona, San Jacinto, and Santa Maria Valleys, and at
recent discoveries near the general vicinities of Norco and Anza in Riverside County (Goocher pers.
comm.). Stephens' kangaroo rat habitat is now estimated to be approximately 1,951 square miles (5,053
km) (U.S. Fish and Wildlife Service 2002). With the recent discovery of Stephens' kangaroo rat at Santa
Maria Valley near Ramona it is likely that the species occurs in other areas of northern San Diego
County that have not been detected (Goocher pers. comm.).
The only location where Stephens' kangaroo rat may actually occur on National Forest System lands in
southern California is along the northern edge of the Warner Springs/Lake Henshaw area, where suitable
habitat may extend onto the Cleveland National Forest (Stephenson and Calcarone 1999, U.S. Fish and
Wildlife Service 2001). Pamo Valley consists of grasslands subject to grazing which can be beneficial
to this species. Given that Pamo Valley generally occurs between Santa Maria Valley and Guejito (two
areas of known occupied habitat), it may reasonable to find Stephens' kangaroo rat in this area as well.
Consideration should be given to assessing potential/suitable habitat in the Pamo Valley and adjacent
Forest Service lands (Goocher pers. comm.). Surveys conducted near Puerta la Cruz Conservation
Camp during September-October confirmed the presence of Stephens' kangaroo rat on National Forest
System lands (Spencer 2003). Systematics
Stephens' kangaroo rat is in the Heteromyidae family. Twenty-one species are recognized in the genus
Dipodomys (Bleich 1977). No subspecies of Stephens' kangaroo rat are recognized (Hall 1981). Habitat Requirements
Stephens' kangaroo rat inhabits sparse grassland habitats in areas with penetrable soils and flat to
moderately sloping topography. These areas include the base of hillsides, flat areas along ridgetops,
sandy washes, and open fields (O'Farrell and Uptain 1989). In addition, Stephens' kangaroo rat habitat
is characterized by low percentages of vegetative cover with large areas of bare ground during the
summer and fall. Vegetation consists of native and nonnative annual herbaceous plants and grasses.
They may also occur in some coastal scrub or sagebrush (such as encelia (Encelia farinosa), coastal
sagebrush (Artemisia californica), and California buckwheat (Eriogonum fasciculatum) with sparse (less
than 30 percent) canopy cover and in disturbed areas (O'Farrell and Clark 1987, O'Farrell and Uptain
1989, U.S. Fish and Wildlife Service 2001).
Stephens' kangaroo rat generally tends to excavate burrows in firm soil that is neither excessively hard
nor excessively sandy (Lackey 1967). Although hard soils, such as clay, become workable with rains
and may be used if gopher burrows are present (Goocher pers. comm.). Thomas (1975) found that most
individuals occupied abandoned pocket gopher burrows. This species is not found in heavily alkaline
soils, highly rocky soils, shallow soils, areas exceeding 50 percent slope, or above elevations of
approximately 4,000–4,580 feet (1,220–1,400 meters) (O'Farrell and Uptain 1989, U.S. Fish and
Wildlife Service 2001, U.S. Fish and Wildlife Service 2002). Reproduction
The breeding season of this species generally occurs in winter (December–February) and spring (March–
May). Although reproductively active females have been documented in nearly every month, they were
often absent in September, October, and November (McClenaghan and Taylor 1993, O'Farrell 1993,
Price and Kelly 1994), and may coincide with rainfall and increased availability of food. Litter size is
generally two to three, with young emerging from burrows by late spring (U.S. Fish and Wildlife
Service 2001). During years with higher rainfall the length of the breeding season is extended and first
year females can become reproductively active and produce young (O'Farrell 1993). An increase in
rainfall is also positively correlated with the number of litters per female and the number of first year
females that breed (Price and Kelly 1994). Daily/Seasonal Activity
This species is nocturnal and active year-round (Bleich 1977). Stephens' kangaroo rat emerges from the
burrow at night to forage around the burrows, returning to the burrows throughout the night to store
gathered food (U.S. Fish and Wildlife Service 2001). Diet and Foraging
Stephens' kangaroo rat is known to eat filaree, brome grass and other annual grasses and forbs, seeds
and, to a limited extent, insects (Thomas 1975, U.S. Fish and Wildlife Service 2001). Territoriality/Home Range
Densities of Stephens' kangaroo rat range from 3–23.7 individuals per acre (7.4 to 58.6 individuals per
hectare) during summer and from 2 to 6 individuals per acre (4.9 to 14.8 per hectare) during fall and
winter (Price and Endo 1989, Thomas 1975). Thomas (1975) also indicates that home range size varies
from approximately 0.1 acre to nearly 0.4 acre (0.05 hectare to nearly 0.2 hectare). Predator-Prey Relations
Predators of Stephens' kangaroo rat include owls, snakes, and predatory mammals (Zeiner and others
1990). The effect of nonnative predators, such as domestic cats, can have significant impacts on local
fauna in an urbanized environment (Crooks and Soule 1999). Literature Cited
Bleich, V.C. 1977. Dipodomys stephensi. Mammalian Species 73: 1–3.
Bleich, V.C.; Price, M.V. 1995. Aggressive behavior of Dipodomys stephensi, an endangered species,
and Dipodomys agilis, a sympatric congener. Journal of Mammalogy 76 (2): 646–651.
California Department of Fish and Game. 2000. The status of rare, threatened, and endangered animals
and plants of California, Stephens' kangaroo rat. Sacramento, CA.
California Department of Fish and Game (Ed.). 2003. California's threatened and endangered species -
Stephens' kangaroo rat. [Homepage of California Department of Fish and Game], [Online]. Available:
http://www.dfg.ca.gov/te_species/index/classification/mammalslist/stephenskrat.html.
Crooks, K.R.; Soulé, M.E. 1999. Mesopredator release and avifaunal extinctions in a fragmented
system. Nature, 400: 563-566.
Goldingay, R.L.; Price, M.V. 1997. Influence of season and a sympatric congener on habitat use by
Stephens' kangaroo rat. Conservation Biology 11(3): 708–717.
Hall, E.R. 1981. The mammals of North America. 2d ed. New York: John Wiley and Sons.
Lackey, J.A. 1967. Biosystematics of heermanni group kangaroo rats in southern
California. Transactions of the San Diego Society of Natural History 12: 477–480.
McClenaghan, L.R., Jr.; Taylor, E. 1993. Temporal and spatial demographic patterns in Dipodomys
stephensi from Riverside County, California. Journal of Mammalogy 74: 636-645.
O'Farrell, M.J. 1993. Stephens' kangaroo rat translocation studies at the Lake Mathews ecological
reserve. Prepared for the Metropolitan Water District of Southern California.
O'Farrell, M.J.; Clark, W.A. 1987. Habitat utilization by Stephens' kangaroo rat (Dipodomys
stephensi). Report to WESTEC Services, San Diego, California.
O'Farrell, M.J.; Uptain, C.E. 1989. Distribution and status of the Stephens' kangaroo rat. California
Department of Fish and Game.
Price, M.V.; Endo, P.R. 1989. Estimating the distribution and abundance of a cryptic species,
Dipodomys stephensi, and implications for management. Conservation Biology 3(3): 293–301.
Price, M.V.; Kelly, P.A. 1994. An age-structured demographic model for the endangered Stephens'
kangaroo rat. Conservation Biology 8(3).
Price, M.V.; Kelly, P.A.; Goldingay, R.L. 1994. Distances moved by Stephens' kangaroo rat
(Dipodomys stephensi Merriam) and implication for conservation. Journal of Mammalogy 75(4).
Stephenson, J.R.; Calcarone, G.M. 1999. Southern California mountains and foothills
assessment: Habitat and species conservation issues. General Technical Report GTR-PSW-172. Albany,
CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture.
Thomas, J.R. 1975. Distribution, population densities and home range requirements of the Stephens
kangaroo rat (Dipodomys stephensi). Pomona: California State Polytechnic University. M.A. thesis.
U.S. Fish and Wildlife Service. 1988. Final rule – determination of endangered status for the Stephen's
kangaroo rat. Federal Register / Vol. 53, No. 190. September 30, 1988
U.S. Fish and Wildlife Service. 1993. Stephens' kangaroo rat ecological study (Naval Weapons Station,
Fallbrook Annex San Diego County, California). Report to U.S. Navy Southwestern Division, Naval
Facilities Engineering Command - San Diego, California.
U.S. Fish and Wildlife Service. 2001. Biological and conference opinions on the continued
implementation of land and resource management plans for the four southern California national
forests, as modified by new interim management direction and conservation measures (1-6-00-F-773.2).
U.S. Fish and Wildlife Service. 2002. Unpublished GIS data regarding the Stephens' Kangaroo Rat.
Zeiner, D.C.; Laudenslayer, W.F., Jr.; Mayer, K.E.; White, M., eds. 1990. California's wildlife Volume
III: Mammals. Sacramento, CA: California Department of Fish and Game.
Information gathered from California DFG - California Interagency Wildlife Task Group
