chipmunk, rodent of the family Sciuridae (squirrel family). The chipmunk of the E United States and SE Canada is of the genus Tamias. The body of the common Eastern chipmunk, Tamias striatus, is about 5 to 6 in. (13–15 cm) long; the upper parts are reddish brown or grayish brown with a median black stripe and two black stripes separated by a whitish band along each side. The tail, 4 to 5 in. (10–13 cm) long, is hairy and flattened. Food is transported in the expansible cheek pouches. Chipmunks make underground burrows, often with concealed entrances beneath stone walls or trees. Although chipmunks are usually found near the ground, they are excellent climbers. In its northern range the chipmunk goes underground about the end of October but sleeps deeply only during the coldest period. Food for the winter is stored in the burrow. Chipmunks eat nuts, seeds, berries, and insects. Although they are numerous, these animals are not serious threats to crops. The typical life span is 5 years. The chipmunks of W North America belong, like those of E Asia, to the genus Eutamias. Chipmunks are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Rodentia, family Sciuridae.