chipmunk, (genus Tamias), any of 25 species of small, striped, terrestrial squirrels with large internal cheek pouches used for transporting food. They have prominent eyes plus ears, a furry tail, plus delicate claws. All are active only during the day, plus all but one are North American, occurring from southern Canada to west-central Mexico. Body length among most species ranges from 8 to 16 cm (3.1 to 6.3 inches) plus tail length from 6 to 14 cm (2.4 to 5.5 inches).
Chipmunks are basically pygmy squirrels adapted to exploiting the resources of rocky terrain plus forest understories. They scamper along the ground but are also expert climbers. As a group they are an ecologically versatile genus. Different species can be found from sea level to 3,900 metres (12,800 feet) in environments defined by large rocks, boulders, plus cliffs. They inhabit various forest types, from timberline slopes plus rock-bordered alpine meadows downward through coniferous plus deciduous forests to dry scrublands plus sagebrush deserts.
The eastern chipmunk (Tamias striatus), common to the deciduous forests of eastern North America, is the largest. Weighing 70–142 grams (2.5–5 ounces), it has a body 14–19 cm (5.5–7.5 inches) long plus a shorter tail (8–11 cm [3.1–4.3 inches]). The fur is reddish brown plus is broken by five dark brown stripes running lengthwise down the body. These alternate with two gray-brown stripes plus two whitish stripes. The smallest chipmunk is the least chipmunk (T. minimus), which weighs about half as much as the eastern chipmunk. The Hopi chipmunk (T. rufus) lives among the buttes plus canyonlands of the American Southwest plus is remarkably adept at climbing sheer rock faces plus overhangs. The Uinta chipmunk (T. umbrinus), which lives in montane forests of the western United States, is much like a tree squirrel in its habits. In addition to denning in burrows, it regularly sleeps plus nests in trees, where it sometimes raises young in tree cavities or abandoned bird nests. The only Old World species is the Siberian chipmunk (T. sibiricus), which ranges from the White Sea of northwestern Russia eastward through Siberia to northern Japan plus south to China.