Identity
Unique IDELEMENT_GLOBAL.2.103814
Element CodeAMAFD03080
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNEndangered
Endemicendemic to a single state or province
KingdomAnimalia
PhylumCraniata
ClassMammalia
OrderRodentia
FamilyHeteromyidae
GenusDipodomys
Concept ReferenceWilson, D. E., and D. M. Reeder (editors). 1993. Mammal species of the world: a taxonomic and geographic reference. Second edition. Smithsonian Institution Press, Washington, DC. xviii + 1206 pp. Available online at: http://www.nmnh.si.edu/msw/.
Conservation Status
Review Date2014-09-23
Change Date2014-09-23
Edition Date2011-04-06
Edition AuthorsWilliams, D. F., and G. Hammerson
Threat ImpactMedium
Range Extent5000-20,000 square km (about 2000-8000 square miles)
Number of Occurrences6 - 20
Rank ReasonsConfined to southern California; most populations occupy relatively small areas of suitable habitat; habitat still being lost to various kinds of development; recent protection on the Carrizo Plain has alleviated threats somewhat; lack of appropriate habitat management on conservation lands may be resulting in habitat degradation in some areas.
Range Extent CommentsThe range is confined to a narrow strip along the southwestern border of the San Joaquin Valley and a few nearby valleys to the west, including the Carrizo and Elkhorn plains and upper Cuyama Valley, with scattered colonies in the Ciervo, Kettleman, Panoche, and Turney Hills, and the Panoche Valley (Grinnell 1922, Hall 1981, Williams and Kilburn 1991, Williams et al. 1993). Historical range extended from Merced County south to the base of the Tehachapi Mountains in Kern County, and west to eastern San Luis Obispo County and extreme northern Santa Barbara County (Williams et al. 1993). Elevational range extends to about 868 meters (400-2,850 feet).
The population is currently fragmented into six major geographic units: 1) the Panoche region in western Fresno and eastern San Benito counties; 2) Kettleman Hills in Kings County; 3) San Juan Creek Valley in San Luis Obispo County; 4) western Kern County in the area of the Lokern, Elk Hills, and other uplands around McKittrick, Taft, and Maricopa; 5) Carrizo Plain in eastern San Luis Obispo County; and 6) Cuyama Valley in Santa Barbara and San Luis Obispo counties (see USFWS 1998). These major units are fragmented into more than 100 smaller populations, many of which are isolated by several miles of barriers such as steep terrain with plant communities unsuitable as habitat, or agricultural, industrial, or urban land without habitat for this species (USFWS 1998).
Occurrences CommentsThe extant distribution includes more than 100 more or less distinct populations, but most of these represent fragments of a formerly more continuous distribution. There are six major geographic units, each of which could be regarded as a single occurrence or subpopulation.
Threat Impact CommentsThe decline is largely a result of conversion of habitat to agricultural uses, combined with additional loss of habitat to industrial uses (e.g., petroleum exploration and extraction) and urbanization, and population reductions and extirpations from rodenticide use (aimed at California ground squirrel and historically at kangaroo rats) (Williams 1992, USFWS 1998). Possibly excessive livestock grazing may have contributed to the decline in some areas (livestock may crush near-surface burrows and compete for food with kangaroo rats) (see USFWS 1998). Between 1972 and 1980 most of the remaining habitat was converted from native vegetation to cultivated agricultural crops due in part to an abundance of irrigation water supplied by recently completed water delivery systems.
More recently, conversion of habitat to agricultural uses has slowed substantially, but urban and industrial developments, petroleum and mineral exploration and extraction, new energy and water conveyance facilities, and construction of communication and transportation infrastructures continue to destroy habitat and increase the threats to the species by reducing and further fragmenting populations (USFWS 1998). Habitat degradation due to lack of appropriate habitat management on conservation lands, especially lack of grazing or fire to control density of vegetation (including shrubs) may be a threat (Williams and Germano 1993).