Sonoma chipmunks are small ground-dwelling rodents in the squirrel family. These chipmunks have 5 black to brown stripes running along their body with white stripes in between. The rest parts of the body range from tawny to cinnamon to gray. Their belly is grayish white and tail is edged in white. Sonoma chipmunks have summer and winter pelage. The winter pelage is generally slightly darker and duller than the summer pelage.
Sonoma chipmunks are found only in California, north of the San Francisco Bay. Most of their range is within Sonoma and Marin counties. These chipmunks live in areas of forest or chaparral. They can be found in forests of sticky laurel, Ponderosa pine, Douglas fir, spruce, redwood, and black oak. They are generally associated with coniferous forests. The chaparral that Sonoma chipmunks inhabit is characterized by sagebrush plains.
Sonoma chipmunks are solitary creatures. They typically live on the ground and make burrows in the ground, but they can climb and may make nests in trees. These small animals are active during the day and forage on the ground or climb along small branches in the brush. They collect food in their cheek pouches and store it in their burrows. These chipmunks also like to find elevated places to eat collected food and rest so they can watch the surrounding area for predators. They don't hibernate but they undergo torpor in winter and awake periodically to eat from their food cache. Sonoma chipmunks have high-pitched, bird-like alarm calls that differ from other chipmunks and are produced to potential threats. Females are usually the ones to make alarm calls. When an alarm call is heard, the chipmunk will quickly move along a direct path to a covered, protected area and become still.
Little information is known about the mating system in Sonoma chipmunks. They breed anywhere from February to July, but most often in April-May. There is occasionally a second breeding season for females if their first litter is lost. The gestation period lasts for 28-36 days. Females give birth to 3-5 young, but it is usually 4. The babies are weaned after approximately 3 weeks, and the mother stops taking care of them. The juveniles stay together for a few more weeks after their mother leaves. After this, the juveniles disperse. Males disperse in a larger range than females. Sonoma chipmunks reach reproductive maturity within one year of age.
Currently, there no major threats to Sonoma chipmunks.
According to IUCN, the Sonoma chipmunk is locally common and widespread throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.