Photo Credit: Denise Clark, UGSS
| Historically present | |
| Currently present | |
| Currently not detected |
| File name | Lead Author | Year | Type |
|---|---|---|---|
| A Field Study of Small Vertebrate Use of Wildlife Underpasses in San Diego County, 2014 | Brehme, Cheryl; Clark, Denise; Fisher, Robert N.; Rochester, Carlton; Tracey, Jeff | 2014 | report |
| Habitat Management Plan for the Kelly Ranch Habitat Conservation Area | 2002 | report |
Restricted to the central and northern Baja California Peninsula and southwestern California [1]. Range is widespread in the valleys of western Riverside and southwestern San Bernardino counties extending northwest to the vicinity of Claremont in Los Angeles County [2;3; both cited in 4]. Also found throughout western Baja California south to extreme northwestern Baja California Sur [2;5; both cited in 4]. Elevational range is from sea level to 1350 m (4500 ft) (Santa Rosa mountains, Riverside county) and 1800 m (6000 ft) (Cactus Flat, north slope of San Bernardino mountains) [6].
Within the MSPA, occurrences have been found in MU 1 (Sunset Cliffs), MU 3 (Crestridge), MU 4 (Mission Trails Regional Park, Sycamore Canyon and Goodan Ranch, Cleveland national Forest), MU 7 (TorreyPines), MU 6 (Elfin Forest Recreational Reserve, Santa Fe Valley), and MU 11 (Cleveland National Forest).
SSC
Common resident of sandy herbaceous areas, usually in association with rocks or coarse gravel [7;8; both cited in 6] in southwestern California. Occurs mainly in arid coastal and desert borders [6]. Habitats tend to be stony soils above sandy desert fans and rocky areas within shrub communities such as coastal sage scrub, chamise-redshank chaparral, mixed chaparral, sagebrush, desert wash, desert scrub, desert succulent scrub, pinyon-juniper, and annual grassland [9, cited in 1;6].
C. fallax has 6 recognized species [10] with two subspecies found in southern California: C. f. fallax from southern California through the coastal sage zone into the northern part of the Baja California Peninsula and C.f. pallidus in the eastern San Bernardino Mountains in California [1;4;10]. Formerly recognized as a subgenus of Perognathus before elevated to full generic stature 11, cited in 12].
Nocturnal [6;13]. Solitary [13]. Active year-round [6] though avoids high daytime temperatures in its burrows [8, cited in 6].
Breeding occurs chiefly from March to May [14]. Females can produce 1-3 litters per year [15, cited in 13]. An average of 4 young comprise a litter. Gestation is around 24-26 days [14]. Young become sexually mature at 5 to 6 months of age. Typical longevity in nature is only 4-6 months, but it is not unusual for some individuals to survive 1-2 years [15, cited in 13].
Forages on seeds of forbs, grasses, shrubs with a low to moderate preference for forb and shrub seeds, and a high preference for grass seeds [16]. Seeds transported within cheek pouches where it is stored in and around its burrow. May feed on some insects. Water obtained metabolically [6].
Home range varied from 0.19 to 0.45 ha, averaging 0.3 ha [17, cited in 10] No difference between sexes in home range size, and little overlap between sexes in home ranges, possibly the result of territoriality [10]. Territory probably the same size as home range [6].
Threatened by habitat fragmentation and loss due to development [13].
[1] Rios, Evelyn, and Sergio Ticul Ãlvarez-Castañeda. 2010. Phylogeography and Systematics of the San Diego Pocket Mouse (Chaetodipus fallax). Journal of Mammalogy 91(2): 293-301.
[2] Hall, E. R. 1981. The Mammals of North America, 2nd edition. John Wiley & Sons, New York.
[3] Williams, F.N., Stace, C.A., Gornall, R.J., Squirrell, J. and Shi, Y., 1993. Taxonomy. In In: Genoways, HH, Brown, JH (Eds.), Biology of the Heteromyidae. Special Publications, American Society of Mammalogists.
[4] Erickson, R. A. and M. A. Patten. 1999. Identification and Distribution of Spiny Pocket Mice (Chaetodipus) in Cismontane Southern California. Bulletin of the Southern California Academy of Sciences 98(2): 57-65.
[5] Huey, L. M. 1964. The Mammals of Baja California, Mexico. San Diego Society of Natural History.
[6] Brylski, P. ND. San Diego Pocket Mouse. R. Duke, ed. California's Wildlife. Vol. I-III. California Departmet of Fish and Game, Sacramento, California.
[7] Grinnell, Joseph. 1933. Review of the Recent Mammal Fauna of California, Vol. 40. University of California Press.
[8] Miller, A. H. and R. C. Stebbins. 1964. The Lives of Desert Animals in Joshua Tree National Monument. University of California Press.
[9] Patton, J. L.. and S. T. Alvarex-Castaneda. 1999. Family Heteromyidae. In Mamı´feros del noroeste de Mexico (S. T. Alvarez-Castaneda and J. L. Patton, eds.). Centro de Investigaciones Biolo´gicas del Noroeste, La Paz, Baja California Sur, Mexico.
[10] Lackey, J. A. 1996. Chaetodipus fallax. Mammalian Species 517: 1-6.
[11] Hafner, J. C. and M. S. Hafner. 1983. Evolutionary Relationships of the Heteromyid Rodents. Great Basin Naturalist Memoirs 7:3-29.
[12] Hafner, J. C., J. E. Light, D. J. Hafner, M. S. Hafner, E. Reddington, D. S. Rogers, and B. R. Riddle. 2007. Basal Clades and Molecular Systematics of Heteromyid Rodents. Journal of Mammalogy 88(5): 1129-1145.
[13] Ãlvarez-Castañeda, S.T., Castro-Arellano, I. , and Lacher, T. 2016. Chaetodipus fallax. The IUCN Red List of Threatened Species 2016. Available: http://www.iucnredlist.org/details/4330/0. Accessed: November 20, 2017.
[14] Hayden, P., J. J. Gambino, and R. G. Lindberg. 1966. Laboratory Breeding of the Little Pocket Mouse, Perognathus longimembris. Journal of Mammalogy 47:412-423.
[15] Wilson, D.E. and Ruff, S. 1999. The Smithsonian Book of North American Mammals. Smithsonian Institution Press, Washington, DC, USA.
[16] Meserve, P. L. 1976. Food Relationships of a Rodent Fauna in a California Coastal Sage Scrub Community. Journal of Mammalogy 57(2): 300-319.
[17] MacMillen, R. E. 1964. Population Ecology, Water Relations, and Social Behavior of a southern California Semidesert Rodent Fauna.