Chipmunk is the common name for any small squirrel-like rodent species of the genus Tamias in the family Sciuridae. Around 25 species fall under this name, mainly in North America, although one species is native to Eurasia.
Though they are commonly depicted with their paws up to the mouth, eating peanuts, or more famously their cheeks bulging out on either side, chipmunks eat a variety of foods. Their omnivorous diet consists of grain, nuts, birds' eggs, small frogs, fungi, worms, and insects. At the beginning of autumn, many species of chipmunk begin to stockpile these goods in their burrows, for winter. Other species make multiple small caches of food. These two kinds of behavior are called larder hoarding and scatter hoarding. Larder hoarders usually live in their nests until spring.
These small squirrels 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.
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 construct expansive burrows which can be more than 3.5 m in length with several well-concealed entrances. The sleeping quarters are kept extremely clean as shells and feces are stored in refuse tunnels.
If unmolested they often become bold enough to take food from the hands of humans. The temptation to pick up or pet any wild animal should be strictly avoided, however. Chipmunk bites can transmit virulent and dangerous bacterial infections. Chipmunks also may attract birds and other predators.