Chaetodipus californicus is native to California in the Western United States and northern Baja California state in northwest Mexico. It is found in habitats, such as California chaparral and woodlands, in Southern California throughout the Southern Sierra Nevada, Southern California Coast Ranges, and the Transverse Ranges; and in Southern California and northern Baja California in the Peninsular Ranges.
The dental formula of Chaetodipus californicus is 220.127.116.11.0.1.3 × 2 = 20 teeth in total.
Its fur is brown on top and tan underneath with distinct white hairs, or spines, near the rump. The tail is dark on top, light underneath and tufted at the end. Females and males are about the same size, showing no sexual dimorphism. C. californicus is often mistaken for C. fallax (San Diego pocket mouse) which shares some of the same habitat but has smaller and rounder ears. Its total tail length is 190–235 mm, tail length is 102–143 mm, and weight is 18-29 g.
The California pocket mouse is mainly a granivore, feeding mainly on seeds. However, it also eats insects and leaves. Like all members of the Family Heteromyidae, C. californicus has external cheek pouches which it uses to store seeds.
The distribution of California pocket mice (Chaetodipus californicus) is restricted to the state of California, ranging from San Francisco Bay south to the border of Baja California, and eastward to the edge of the Central Valley. C. californicus is also encountered on the west side of the Central Valley, along the foothills of the Sierra Nevada. This species is found from the town of Auburn south, and west across the Tehachapi Mountains to the coast.
Biogeographic Regions: nearctic (Native )
C. californicus is large for a pocket mouse. Its overall body length is 190-224 mm, with a tail length of 103-143 mm. The tail features a distinctive tuft measuring 9-14 mm. The ears and hind feet, import characters when distinguishing C. californicus from other members of its genus, measure 9-144 mm and 24-29 mm respectively. Overall body coloration is brownish-gray on top, and yellowish-white underneath, with a distinctive brownish line on the side. Conspicuous white, grooved hairs, or spines, are found on the rump. Like the body, the tail is brownish above and light below, with a prominent tuft of hairs at its base. Ears are large for a pocket mouse, with long black or buffy hairs at their base nearly as long as the ear. Hind feet are also large, and their color is yellowish-white. The average weight for this species is 23 g.
The San Diego Pocket Mouse (C. fallax) is easily confused with C. californicus. Although the two species are largely allopatric, with C. californicus to the north and C. fallax to the south, some overlap between species ranges can occur in cismontane southern California. As mentioned above, length of the ears and hind feet are the most reliable characters for distinguishing between the two species. The ears of C. fallax are shorter and rounder, with a length of 7-9 mm and its hind feet, at 21-26 mm, are slightly smaller than those of C. californicus.
Average mass: 23 g.
Range length: 190 to 224 mm.
Sexual Dimorphism: sexes alike
Other Physical Features: endothermic ; bilateral symmetry
C. californicus occupies a wide variety of habitats year-round within its range in the Upper Sonoran and Transition life zones. These include montane hardwood, valley foothill hardwood-conifer, valley foothill hardwood, annual grassland, sagebrush, chamise-redshank and montane chaparral, and coastal scrub. C. californicus occurs in greatest abundance in habitats where grassland and chaparral are in close proximity. In central California, this species is found at low to moderate elevations, whereas in southern California it is found primarily at moderate elevations. The species is restricted to high elevations at the southernmost portion of its range in the Sierra San Pedro Martir, with an overall range in elevation from sea level to 2400 m.
Range elevation: 0 to 2,400 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: chaparral ; forest
C. californicus is primarily a grainivore, consuming the seeds from annual grasses and forbs. Insects and leafy vegetation supplement this diet seasonally. C. californicus rarely, if ever, drinks water, obtaining its water through moisture stored in seeds and leafy vegetation. The forefeet of C. californicus are equipped with long claws, which are used to sift for seeds buried in soil. The mice then place the seeds in external cheek pouches.
Animal Foods: insects
Plant Foods: leaves; seeds, grains, and nuts
Foraging Behavior: stores or caches food
Primary Diet: herbivore (Granivore )
As small prey items, these animals probably affect populations of their predators. As seed cachers, they likely play some role in distributing seeds. As fossorial animals, they help to aerate the soil.
Ecosystem Impact: disperses seeds; soil aeration
C. californicus is preyed upon by a variety of terrestrial and avian predators common in California.
These mice have a variety of means of communication. Scent marking of the territory occurs when these animals take dust baths near the periphery of their territories, depositing some of their odorous secretions (produced by glands at the base of the tail) in the dirt. C. californicus is also known to make an aggressive, tooth-chattering noise, and will growl when threatened. These animals make a higher-pitched squeal when they are injured or attacked.
Communication Channels: acoustic ; chemical
Perception Channels: visual ; tactile ; acoustic ; chemical
The longevity of this species has not been reported. However, a congener, C. fallax, was reported to have lived an amazing 8 years and 4 months in captivity--an impressive lifespan for such a small rodent.
The mating system of these animals has not been reported.
C. californicus typically produce one litter a year (occasionally two) between April and July. Litter size ranges from 2-7, with and average of 4 young. Gestation takes about 25 days, and young are typically weaned in about three weeks. Females reach reproductive maturity around the age of 3 months, which is when they reach their adult size. Little other information is available on the reproductive biology of this species.
Breeding interval: These mice are reported to produce one litter annually.
Breeding season: These mice breed between March and June, producing litters between April and July.
Range number of offspring: 2 to 7.
Average number of offspring: 4.
Average gestation period: 3-4 weeks.
Average weaning age: 3 weeks.
Average age at sexual or reproductive maturity (female): 3 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous
Not much is known about the parental behavior of these animals. Adult females give birth to their young in burrows dug in soft soil. The young are nursed for approximately 3 weeks. They probably disperse sometime shortly after weaning. No male parental care has been reported for these animals.
Parental Investment: no parental involvement; pre-fertilization (Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
C. californicus is threatened by habitat loss where human development occurs in its range. Grazing activity of domestic livestock reduces cover necessary for predator avoidance.
IUCN: A subspecies, C. californicus femoralis (Dalzura pocket mouse), is listed as DD (Data deficient).
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
No negative impact on humans has been reported for this species.
These animals are not known to positively affect humans.
Studies indicate that hypothermic C. californicus show significantly higher hepatic ATP levels than non-hypothermic control groups. This suggests a metabolic heat arousal mechanism similar to that used by 13-lined ground squirrels Citellus tridecemlineatus.
Eight subspecies have been described in southern California: C. californicus bensoni, C. californicus bernardinus, C. californicus califonicus, C. californicus dispar, C. californicus femoralis, C. californicus mariniensis, C. californicus mesopolius,and C. californicus ochrus.