The California chipmunk (Neotamias obscurus) is a species of rodent in the squirrel family Sciuridae. They are an important part of the ecology of the San Bernardino Mountains.
Small and striped rodents, chipmunks are generally classified either as a single genus, Tamias (Greek: ταμίας), or as three genera: Tamias, which includes the eastern chipmunk; Eutamias, which includes the Siberian chipmunk; and Neotamias, which includes the 23 remaining, mostly western, species. These classifications are arbitrary, and most taxonomies over the twentieth century have placed the chipmunks in a single genus. However, studies of mitochondrial DNA show that the divergence between each of the three chipmunk groups is comparable to the genetic dissimilarity between Marmota, which are large squirrels, and and Spermophilus ,which are generally smaller.
The genus name Tamias is Greek for “treasurer”, “steward”, or “housekeeper”, which is a reference to the animals’ role in plant dispersal through their habit of collecting and storing food for winter use.
The common name originally may have been spelled “chitmunk,” from the native Odawa (Ottawa) word jidmoonh, meaning “red squirrel.” The earliest form cited in the Oxford English Dictionary (from 1842) is “chipmonk,” however, “chipmunk” appears in several books from the 1820s and 1830s. Other early forms include “chipmuck” and “chipminck,” and in the 1830s they were also referred to as “chip squirrels;” probably in reference to the sound they make. In the mid-1800s, John James Audubon and his sons included a lithograph of the chipmunk in their Viviparous Quadrupeds of North America, calling it the “chipping squirrel [or] hackee.” Chipmunks have also been referred to as “striped squirrels,” “chippers,” “munks,” “timber tigers,” and “ground squirrels,” although the name “ground squirrel” usually refers to other squirrels, such as those of the genus Spermophilus.
Chipmunks have an omnivorous diet primarily consisting of seeds, nuts and other fruits, and buds, including pinyon nuts, acorns, manzanita and juniper fruits. They also commonly eat grass, shoots, and many other forms of plant matter, as well as fungi, insects and other arthropods, small frogs, worms, and bird eggs. Around humans, chipmunks can eat cultivated grains and vegetables, and other plants from farms and gardens, so they are sometimes considered pests. Chipmunks mostly forage on the ground, but they climb trees to obtain nuts such as hazelnuts and acorns. At the beginning of autumn, many species of chipmunk begin to stockpile nonperishable foods for winter. They mostly cache their foods in a larder in their burrows and remain in their nests until spring, unlike some other species which make many small caches of food. Cheek pouches allow chipmunks to carry food items to their burrows for either storage or consumption.
Water sources other than food are not necessary for survival, but are used if available.
Western chipmunks breed only once a year, from January to June. Most females lactate in May. A litter size averages about four. The young emerge from the burrow after about six weeks and strike out on their own within the next two weeks.
These small mammals fulfill several important functions in forest ecosystems. Their activities harvesting and hoarding tree seeds play a crucial role in seedling establishment. They consume many different kinds of fungi, including those involved in symbiotic mycorrhizal associations with trees, and are an important vector for dispersal of the spores of subterranean sporocarps (truffles) which have co-evolved with these and other mycophagous mammals and thus lost the ability to disperse their spores through the air.
California chipmunks are abundant in pinyon-juniper, chamise-redshank and mixed chaparral, and ponderosa pine habitats within range. They flourish at elevations from 2,500 to8,500 feet.
Chipmunks construct expansive burrows which can be more than 11 feet in length with several well-concealed entrances. The sleeping quarters are kept clean as shells and feces are stored in refuse tunnels.
The eastern chipmunk hibernates in the winter, while western chipmunks do not, relying on the stores in their burrows.
In the summer, chipmunks use rocks, logs, brush, and trees for cover. They retreats to shade when the weather grows hot.
Chipmunks play an important role as prey for various predatory mammals and birds but are also opportunistic predators themselves, particularly with regard to bird eggs and nestlings. In Oregon, mountain bluebirds (Siala currucoides) have been observed energetically mobbing chipmunks that they see near their nest trees.]
Chipmunks typically live about three years although some have been observed living to nine years in captivity.
Chipmunks in captivity are said to sleep for an average of about 15 hours a day.