Tamias obscurus
California chipmunk

California chipmunks, Tamias obscurus, can be found throughout the San Bernardino and San Jacinto mountains of southern California in a series of disjunct populations. Their range also extends southward, across desert ranges into Baja California, reaching as far south as the Sierra de San Francisco. (Best and Granai, 1994)

They are typically found at elevations between 760 and 600 m (Callahan, 1977). These chipmunks occupy lower Sonoran, upper Sonoran, transition, and Canadian life zones (Best and Granai, 1994). Their habitat can also be described by the botanical wildlife in the areas; usually these are pinyon-juniper or pine-oak forests, often with manzanita or sage, and nearby rocky outcroppings (Best and Granai, 1994). North of San Gorgonio Pass, T. obscurus is replaced by Tamias merriami at elevations above pinyon-juniper habitat. However, the opposite occurs in communities south of San Gorgonio Pass. Tamias obscurus occurs alone in the Santa Rosa Mountains (Callahan, 1977). (Best and Granai, 1994; Callahan, 1977)

Through much of their range, California chipmunks are indistinctly colored. During the warmer summer months, the head is pale gray shaded with cinnamon, bordered on the sides with snuff brown, extending down to the snout as clay-redbrown. The facial stripes are dark brown, with blackish stripes around the eyes, offset by paler-gray stripes. On the dorsal side of the trunk, pelage has dark russet-brown stripes offset by a median pair of the pale gray stripes. The ventral pelage is creamy white. During the winter the pelage is very similar, but the dorsal stripes are more pronounced and the sides of the chipmunk become a pale brown (Best and Granai, 1994).

Average total length of these animals is 208 to 240 mm, of which the tail comprizes 91 to 99 mm. The hindfoot varies between 33 and 35 mm, and the weight varies betweeen 56 and 90 g (Callahan, 1977). Females are typically larger than males in cranium length, rostral length, zygomatic breadth, and several characters, but males have wider nasals than females (Best and Granai, 1994).

Tamias merriami, which has an overlapping range with California chipmunks, is superficially similar to T. obscurus. However, T. obscurus may be readily distinguished by the shape of the ossa genitalia, a longer hind foot, and a more rounded cranium. In the summer, T. obscurus also has paler adult pelage with less yellow with more reddish dorsal stripes than T. merriami (Callahan, 1977).

Unlike many other chipmunks, T. obscurus does not hibernate. If it does not become torpid, it is probably homoiothermic. All mammals are endothermic. (Best and Granai, 1994; Blankenship, 1999; Callahan, 1977)

There is little information published regarding longevity in this species, but one T. obscurus is known to have lived in captivity for 10 years (Best and Granai, 1994).

This diurnal chipmunk is active throughout the year. The greatest amount of foraging and activity takes place in early morning and late afternoon. (Callahan, 1977). Tamias obscurus often creates burrows in logs or steep hillsides that are protected by the use of large boulders (Best and Granai, 1994). (Blankenship and Brand, 1987; Callahan, 1977)

Home Range

Data are not available on the home range size of these animals. However, if they are like other members of the genus Tamias, males have slightly larger ranges than females. (Blankenship, 1999)

Tamias obscurus uses vocalizations such as the chuck, trill, chatter, and chip (Blankenship and Brand, 1987). Calls are thought to be somewhat species specific, and may be a way for T. obscurus to recognize potential mates. Species specific vocalizations might play a role in reproductive isolation of sympatric species. (Blankenship adn Brand, 1987).

Although not specifically reported for this species, it is likely that California chipmunks use visual cues such as body positioning, tail position, and tail flicking in their communication, as these behaviors are common in most species in the genus. It can also be assumed that tactile communication occurs, especially during mating and between mothers and their offspring. (Blankenship and Brand, 1987)

Similar to other chipmunks, T. obscurus likely subsists on a variety of seeds and fruits of grasses, forbs, and shrubs. Some of these items may include pinyon nuts, acorns, along with manzanita and juniper berries. They forage mostly along the ground and in shrubs, and often they will set up "feeding stations" perched on top of logs or rocks. Their food is probably also their main water source. (Callahan, 1977) These chipmunks are also known to cache food in their dens or burrows. (Blankenship, 1999; Callahan, 1977)

Reports of predation on these small mammals are not available. However, California chipmunks can use nearby rocks, logs, brush, and trees for cover and to hide from predators. Predation is likely to come from carnivorous animals such as hawks, foxes, and coyotes (Best and Granai, 1994).

These chipmunks probably play some role in seed dispersal, as they transport seeds from the places they are found to feeding stations and food caches. They are likey to be important in local food webs, also, although the extent to which various predatory animals may depend upon them is not known. (Blankenship, 1999)

These chipmunks have no known negative impact on humans.

These chipmunks have no known impact on humans.

These animals have a very limited distribution. As such, it is especially important to protect their habitat to ensure that the species will survive into the future.