An adult eastern chipmunk is five to six inches in head-body length with a three- to four-inch tail. It has five white-and-dark stripe patterns that start at the shoulder and go to the base of the tail. There is a tan stripe above and below each eye and a black line through the eye. The eastern chipmunk has long, soft hair and a bushy tail that is black above and rust-colored below. It has internal cheek pouches for temporary food storage. The ears are short and round.
The eastern chipmunk may be found statewide in Illinois. It lives in deciduous forests that have much underbrush and slopes or ravines and is absent from most bottomland forests and cultivated lands in Illinois. The eastern chipmunk is an omnivore that eats nuts, seeds, fruits, ﬂowers, mushrooms, snails, caterpillars and eggs. Its food is carried in cheek pouches and then stored in burrows. It is mainly active during the day. The eastern chipmunk has a period of inactivity in winter, but it does not hibernate. It uses an underground tunnel system to rest, store food and escape predators. Mating occurs in February and March and in June and July. Young are born after a one month gestation period. Litter size may be two to six young. Young are helpless at birth. They are nursed for about six weeks and attain adult size in about three months.