The Eastern chipmunk (Tamias striatus) is a small stripped rodent found in North America. The name "chipmunk" comes from the Ojibwe word ajidamoo (or possibly ajidamoonh, the same word in the Ottawa dialect of Ojibwe), which translates literally as "one who descends trees headlong." The scientific name of the Eastern chipmunk Tamias striatus can be translated as "striped steward".
The Eastern chipmunk has reddish-brown fur on its upper body and five dark brown stripes contrasting with light brown stripes along its back, ending in a dark tail. It has lighter fur on the lower part of its body. It has a tawny stripe that runs from its whiskers to below its ears, and light stripes over its eyes. It has two fewer teeth than other chipmunks and four toes each on the front legs, but five toes on the hind legs. The chipmunk's appearance "remains consistent throughout life. There is no external difference in appearance between the sexes. Molt occurs once or twice annually, during May or June and sometimes again in October.
Eastern chipmunks are 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 in Newfoundland, off the coast of Canada. The preferred habitat of these rodents is deciduous forest or brushland with rocky ground as well as an abundance of logs and tree stumps. In addition, Eastern chipmunks may share their habitat with humans and often inhabit gardens or suburban areas, surrounding houses, and outbuilding.
Eastern chipmunks are solitary animals. They are active during the day, spending most of their time searching for food. 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 hibernation 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 to each other. They construct their nests out of crushed or chewed leaves in a large chamber. They also line their burrows with leaves, rocks, sticks, and other materials, making the burrows even harder to see. Other chambers serve as food stores. Eastern chipmunks communicate with the chip, the chuck, the trills, the whistle or squeal, and chatter. Their trill has been measured to occur at the rate of 130 vibrations per minute.
Eastern chipmunks are omnivorous rodents. They feed upon bulbs, green plants, fruit, seeds, mushrooms, nuts, insects, earthworms, slugs, and eggs of birds.
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. However, 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 hoarding habit, these rodents prevent seed dispersal of plants, 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. Finally, being common and widespread, the Eastern chipmunks are an important prey species for local predators.
