This small rodent is so called due to being endemic to eastern parts of North America. The Eastern chipmunk is a mainly terrestrial animal, distinguished by 5 dark stripes, stretching along its back, from shoulders to rump, and alternating with 4 light colored stripes. The long, soft coat of this animal often becomes paler during the winter months. Individuals of both sexes look alike. The Eastern chipmunks have pouches on their cheeks, made of extendible skin. These cheek pouches enlarge as the animals age and act as stores, where the chipmunks usually carry large amounts of food to later hoard it at their burrows.
This species is distributed over a huge area throughout the eastern United States and south-eastern Canada. In Canada, their range stretches from Nova Scotia to south-eastern Saskatchewan. In the United States, these animals occur from the eastern parts of the country to Oklahoma and as south as the extreme northwest of Florida. In addition, one introduced population of the Eastern chipmunks is found on Newfoundland, off the coast of Canada. The preferred habitat of these rodents is deciduous forest or brushland with rocky ground as well as abundance of logs and tree stumps. In addition, the Eastern chipmunks may share their habitat with humans and often inhabit gardens or suburban areas, surrounding houses and outbuilding.
These rodents are solitary and diurnal animals. Periods of increased activity are mid-morning and mid-afternoon. Eastern chipmunks are highly territorial, particularly defending areas around their burrows. In spite of being accomplished climbers, they are terrestrial foragers. Although they usually hoard food, these animals don't store fat for hibernation period. Instead, they regularly wake up from hibernation, occasionally leaving the burrow if it's warm enough. The duration of torpor depends on populations and individuals. Some chipmunks may be dormant throughout the winter, whereas others display more activity. Eastern chipmunks live in burrows, which they dig themselves. A typical burrow of this animal is composed of numerous entrances as well as tunnels, which are connected between each other. They construct their nests out of crushed or chewed leaves in a large chamber. Other chambers serve as food stores. In addition, there have been known cases of individuals, nesting in hollow trees.
Eastern chipmunks are generally herbivores, they feed upon fruit, seeds and nuts, complementing this diet with occasional insects, earthworms, slugs, eggs of birds and mushrooms.
Eastern chipmunks are polygynous, which means that one male mates with multiple females. During the breeding season, females remain within their territories, while males come to mate, travelling 170 meters on average from their burrows to the mating sites. Eastern chipmunks have two breeding season, one of which occurs from February to April, and the other lasts from June to August. Gestation period lasts for 35 days, yielding a litter of 2 - 5 young, typically in an underground nest. Newborn babies of this species are altricial, weighing only 3 grams. They are blind and lack fur. Weaning occurs at 40 days old, after which females leave their offspring, moving to a new burrow. After a while, young disperse, becoming independent at about 2 months old. Females usually continue living close to the area, where they have been raised, whereas males disperse farther. Young chipmunks generally start breeding during the first spring of their lives.
The Eastern chipmunks are quite common throughout their range and don't appear to be threatened, but populations in forests are known to suffer from fragmentation of their natural range. In addition, these animals in general face habitat modification.
According to IUCN, the Eastern chipmunk is abundant and widespread across its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) and its numbers remain stable.
Due to their hording habit, these rodents prevent seed dispersal of plant, which they store. Nevertheless, sometimes they scatter-hoard, helping disperse seeds of various plants. In addition, they are key dispersers of fungi spores throughout their range. And finally, being common and widespread, the Eastern chipmunks are an important prey species for local predators.