Eastern Chipmunk     Order Rodentia     Family Sciuridae      Tamias striatus Written by Jean Alamed

Chipmunks inhabit most of the eastern United States, from North Carolina and the Gulf of Mexico to Southern Canada. They are also found in Minnesota, Wisconsin, Iowa, Illinois, and Michigan.

The stripes of the back of a chipmunk is the characteristic tht distinguishes it from all othe rodents. Chipmunks are reddish brown or grayish brown in color with a red patch on the rump. Five black stripes run alon the back and sides with the longest stripe running down the midline. Between the paired black stripes is a band of white. The Eastern chipmunk has two pale and two brown stripes on each side of its face. Its sides and underside are buff to white in color and its feet are tan. The coat of Tamias Striatus is short and fine, and the tail has a short, flattened brush. Eastern chipmunks are the biggest of most chipmunks ranging from 5-12 inches in length with a 2.5-4 inch tail. Another distinctive characteristic of all chipmunks are their pouched cheeks. The pouches are located on each side of the mouth and used to store and transport food. When full, they can be as large as the chipmunk's entire head. Eastern chipmunks have 4 toes on their front feet and 5 toes on their back feet. Tamias striatus has only two teeth in the upper jaw.

Food Habits

The Eastern Chipmunk is onmnivorous. Its diet consists of fruits, seeds, nuts, corn, and mushrooms. Occassionally it is supplementedwith insects, salamanders, bird eggs, and earthworms. Chipmunks transport dry food in their cheek pouches. Food catching occurs at any time during the year, but chipmunks are most active in the autumn, storing food for the coming winter.

Reproduction

Mating occurs twice a year for Tamias striatus. First is in early spring, beginning in February and lasting until April. The second is in late summer, starting in June and ending in August. Chipmunks do not form monogomous pairs. Male-male competition occurs before mating takes place. Females are in estrus for 3-10 days. After a gestation period of 31 days a litter a size of 4-7 young are born. The young are born in an underground nest and do not appear above ground for 6 weeks after they are born. A newborn chipmunk weighs 0.1 oz. At 40 days the young are weaned and recieve no help from either parent. Both male and female Eastern chipmunks reach sexual maturity at 1 year of age.

Behavior

Chipmunks are primarily solitary animals, except during the mating seasons. They are busiest during midmorning and midafternoon. They depend mainly on their eyesight. Chipmunks are territorial. The average territory is about 1/4 to 1/2 acre, and the adult chipmunk aggressively defends an area of about 50 feet around the entrance of its burrow. A chipmunk will vocally threaten an intruder befoe engaging in a noisy chace. Chipmunks are also agressive during mating which, many times, leaves the males seriously wounded. Tamias striatus live in burrows in the ground. The burrows are usually well hidden near trees, banks, rocks, gardens, buildings, and wood piles. Burrows usually have 2-3 entrances with numerous chambers. One chamber is used as a nest site with a bed made out of chewed leaves. The other chambers are used to store food. Chipmunks do not hibernate continuously throughout the winter. They lack the large fat stores of a true hibernator, so they must arouse frequently to feed off the stored food. On some warmer, sunny days during the winter chipmunks will forage for food above the ground. Most chipmunks leave their burrows in March and resume foraging and mating.

Habitat

Eastern chipmunks inhabit open deciduous forests with a readily available cover of logs, stumps, and rocks. They don't like dense forests where no sunlight reaches the ground. The ideal habitat for Tamias striatus is a mature beech-maple forest. They will also live in brushy areas and coniferous forests. With an increasing tolerance for humans, chipmunks will burrow under buildings or stone foundations in rural areas.

Economic Impacts

Chipmunks are key in aiding in the dispersal of seeds of trees, plants, and mycorrhizal fungi. They eat insects which could help control the population of some insect species. Chipmunks have also played a small roll in the fur trade.

When numerous around houses, the Eastern chipmunk can be destructive pests. They can cause structural damage by undermining foundations, sidewalks, and retaining walls. Chipmunks are destructive to gardens as well. They dig up and eat seeds and bulbs as well as attacking garden fruits.

Interesting Facts

The common name "chipmunk" comes from the noise "chip, chip, chip" commonly made by these animals. The name Tamias striatus comes from two characteristics of the chipmunk. Tamias means "the treasurer" and striatus means "striped".

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