The diet of the least chipmunk consists mainly of seeds, nuts and fruits, although it will also take other plant material, such as leaves and flowers, as well as fungi, insects and occasionally birds’ eggs (2) (3) (5) (6) (7). The least chipmunk may also sometimes feed on carrion (3) (6).
While foraging, the least chipmunk will often fill its cheek pouches with seeds and nuts, which it then hoards in various locations or carries to its burrow to store for the winter (2) (4) (7). This behaviour, typical of chipmunks, is reflected in the scientific name of the genus Tamias, which comes from the Greek for ‘storer’ or ‘distributor’ (2).
The least chipmunk is active throughout the day, sheltering in its burrow at night (2) (5) (6) (7). Although mainly terrestrial, this species will sometimes climb trees and bushes (2) (3) (4) (5) (7) and has also been known to nest above ground (1) (2) (5).
Generally, the least chipmunk builds a winter nest inside a burrow up to one metre below the ground (1) (4) (7). Soil is removed through a “work hole”, which is later plugged and a new entrance opened so that the pile of excavated soil does not give away the burrow’s location (2) (7). A chamber inside the burrow is filled with dry grass, shredded bark, fur, feathers and other soft materials, and also contains a cache of stored food (2) (7). In the summer, the least chipmunk may abandon the burrow and instead build a nest in a hollow log, stump, rock pile or tree cavity (1) (2) (4) (7). This species is territorial, defending its nest site against intruders (7),
The least chipmunk hibernates in its underground burrow from about September to April, with the exact timing depending on the location and the amount of snow cover (1) (2) (3) (4) (7). Unlike many hibernators, the least chipmunk does not accumulate large fat reserves in autumn. It must therefore wake occasionally during the winter to eat its stored food (2) (3) (4) (6) (7).
Breeding in the least chipmunk takes place in early spring, soon after individuals emerge from hibernation (1) (3). Most mating takes place in April and May (2) (3) (4), with the young typically being born in late May and early June (3) (5) (7). The female least chipmunk usually gives birth to a single litter of between 2 and 8 young each year (1) (2) (3) (4), after a gestation period of about 28 to 30 days (2) (5). The young are hairless and blind at birth (2) (7), and are suckled for up to 60 days (4) (7). Although the female least chipmunk usually gives birth in the underground burrow, it has been suggested that the young may be moved to a tree nest several weeks later (4) (7).
Young least chipmunks reach sexual maturity within their first year, breeding for the first time in the spring following their birth (1) (4) (7). This species has been recorded living for up to six years (2) (3), although it is vulnerable to a number of predators, including snakes, hawks, weasels, foxes, and domestic dogs and cats (7).