The chipmunk is a member of the squirrel family and they range in color from reddish brown to gray with black and white striping. There are 24 species in North America. They live below ground in burrows or in logs. The small animals live solitary lives, except during mating season, which occurs in the spring months for most species. The eastern chipmunk enters estrus in the spring and again in the late summer.
Chipmunk live only two to three years. When kept in captivity, chipmunks can live up to eight years. The chipmunks will breed in the spring following their birth. They begin to break hibernation and leave their burrows around the beginning of March. A female will be in estrus for three to 10 days. Competition is fierce between males and fighting will erupt. Males often suffer extensive injuries in the battles. To attract females, the male will usually issue a high, chirping sound.
Mating and Gestation
Chipmunks are exceptionally territorial. Typically there will be one chipmunk every one-fourth to one-half acre. They will battle each other to protect their territory. The chipmunk becomes especially ferocious within 50 feet of its burrow's entrance if another chipmunk enters the region. After mating with a female, the male leaves the area. The female will bear and raise the young alone. Her gestation period averages 31 days. A female will bear two to eight fur-less babies. Infant chipmunks cannot see or hear. They also have no teeth.
Development of the Young
The young stay with their mother for two months. At about 10 days they begin to grow fur and their teeth start to grow in. At 28 days the chipmunk's ears open up and they can hear. At 30 days, their eyes open. At approximately 6 weeks old the mother chipmunk will take the babies above ground to begin teaching them how to forage for food. By 40 days old the chipmunks are fully weaned and will head out on their own, with no help from their mother.
Summer Estrus, Burrows and Mortality
After the spring litter, eastern chipmunks will again enter estrus and mate to produce one final litter before winter. Other chipmunk species will finish the summer foraging for food to store for the winter's hibernation. Chipmunks that burrow below ground create an extensive tunnel system that contain a couple of areas for food storage and a nesting chamber. Chipmunks also will have several escape routes leading out of the burrow. The mortality rate for young chipmunks averages 30 percent, according to the Penn State University. Death is usually a result of predators.