Family: Sciuridae, Squirrels view all from this family
Description A small chipmunk. Color varies: in drier regions, muted yellowish gray above with dark stripes tan; in moister areas, brownish gray with black side stripes. Pale stripes white; all of equal width. 2 white areas on flanks continue to base of tail. Sides orange brown; belly grayish white. Long tail light brown above, grayish yellow below, with hairs black-tipped. Ears tawny in front. L 6 5/8–8 7/8" (167–225 mm); T 2 3/4–4 1/2" (70–114 mm); HF 1–1 3/8" (26–35 mm); Wt 1–3 oz (30–85 g).
Similar Species Ears of Uinta, Yellow-pine, Lodgepole, and Colorado chipmunks are dark in front, whitish behind. Gray-collared Chipmunk is larger and more grayish. Townsend’s Chipmunk, also larger, lacks white area on flanks; backs of ears are bicolored: dusky and gray. Eastern Chipmunk is larger; its median pale stripes are much paler and darker than outer ones, which are white. Cliff Chipmunk has indistinct or absent side stripes. Alpine Chipmunk’s tail is bright orange-yellow below.
Breeding Mates within 10–20 days of emerging from hibernation in spring. Gestation about 31 days. 1 litter of 2–7 (usually 5 or 6) young born in May in a nest, often grass-lined, in an underground cavity, stump, log, or tree. A second litter sometimes follows.
Habitat Pastures, piney woods, rocky cliffs, and sagebrush deserts; often abundant in open coniferous forests.
Range Most of s Canada from s Yukon through Ontario; w U.S. from se Washington and nw California east to w North Dakota and New Mexico; also n Minnesota, Wisconsin, and Upper Peninsula of Michigan.
Discussion The Least Chipmunk, palest in color of all the western chipmunks, often lives in the most desert-like habitats and generally enters hibernation much later than the Eastern Chipmunk. Acorns, seeds, fruits, berries, and grasses are its main foods, but it also eats fungi, invertebrates, and (rarely) small vertebrates. An excellent climber, it ascends trees to sun itself and may even nest in them. Its distinctive call, a series of high-pitched chipping notes, is similar to that of the Eastern Chipmunk.
