The Townsend's Chipmunk (Tamias townsendii) is a species of rodent in the Sciuridae family. It is found in Canada and the United States.

A large chipmunk. Dark brown, often with rather wide diffuse or indistinct blackish and pale stripes on head and continuing down body. Paler overall in summer than winter. Backs of ears bicolored: dusky on forepart; gray on hindpart. Brownish stripe below ears. Tail long and bushy; blackish above, with many white-tipped hairs; bright reddish brown below, bordered with black and finely edged with white-tipped hairs.

Long-eared Chipmunk has prominent white patch behind ear. Sonoma Chipmunk has unicolored backs of ears. Other chipmunks in range are smaller, with more distinct stripes.

Mates in spring; 1 litter per year of 2–6 young born May–June.

Found in rank vegetation, usually among dense hardwood or humid coniferous forests. Extreme sw British Columbia south through most of w Oregon.

One of the largest western chipmunks and the darkest in color (as is common among species in moist climates), Townsend’s Chipmunk has a looser, less sleek coat than other species. It is active all day, but rather shy. In northern parts of its range it may put on a layer of fat and remain in a nest burrow all winter, but in milder climates it puts on little or no fat and may be abroad most of the winter. It forages within a home range of 1 1/2 acres ( 1/2 ha), eating many types of berries in summer, switching in late fall to acorns, maple seeds, and seeds of various conifers, and in winter to numerous types of subterranean fungi. It also eats some insects. Townsend’s Chipmunk lives in a burrow about 2 inches (50 mm) across and only 5 feet (1.5 m) long. A very good climber, it often suns itself in trees and may run up a tree to flee a predator. Its major predators are the Long-tailed Weasel and the Mink. One tagged specimen lived in the wild for at least seven years, unusual longevity for a small rodent. Chipmunks previously recognized as belonging to this species have been split into several species: Townsend’s, Allen’s, Yellow-cheeked, and Siskiyou. These divisions were based primarily on differences in the penis bone and the call. The four species do not interbreed where they occur together.