About Chipmunks

Chipmunk © Shawn P. Carey (Migration Productions)
© Shawn P. Carey (Migration Productions)

The eastern chipmunk (Tamias striatus), is in the squirrel family and the order Rodentia, or rodent. It is believed that the word “chipmunk” is derived from the word chetamnon, the name given to it by the Chippewa Indians. 

Eastern chipmunks are found in the United States east of the Great Plains, north to Maine, and south to parts of Florida. They are commonly seen in forests and woodlots where they forage for food in leaf litter as well as in suburban yards and city parks.

These industrious creatures are diurnal (active during the day) and they spend their days gathering and storing food in their burrows, which will sustain them during the winter. 

Appearance

Chipmunks have short, dense fur that is reddish rust on top. There are five black stripes on the back, one down the center, and two on each flank outlining a white stripe. There is a white eyeline above and below each eye, separated by a slash of black.

With a body 5 to 6 inches long and a tail 3 to 4 inches long, chipmunks are about a third the size of the gray squirrel. As chipmunks scamper along the ground they hold their flat, hairy tail in the air.

Food

Seeds, berries, nuts, and fruit are the mainstay of the chipmunk's diet, but they also eat insects, insect larvae, slugs, snails, and earthworms. Occasionally they will eat birds such as sparrows, juncos, and starlings, bird's eggs, frogs, and small snakes.

Chipmunks possess cheek pouches in which they store food before depositing it in their burrow. Researchers have reported watching a chipmunk stuff nearly 6 dozen black-oil sunflower seeds in its pouches. 

Life Cycle

Eastern chipmunks in Massachusetts usually mate twice a year, once in the early spring from March to early April and again from early June to mid-July. The female rebuffs the male after mating and he does not share in the rearing of the young.

A litter of 2-5 tiny (2.5 inch), hairless, and blind young are born after a 31 day gestation period. The first litter is generally born in April and May, and the second in July and August.

At 6 weeks, under their mother's watchful eye, they begin to take short trips out of the burrow. At week 7 or 8, the mother becomes more aggressive toward her offspring to prepare them for their independence. Two weeks later, the mother denies them access to the burrow; the young are forced to disperse and find or dig their own.

When the young disperse in the spring and fall, adults occupying nearby burrows give loud "chip-chip-chip" calls outside the burrow entrance presumably, to notify the young of occupied territory.

Hibernation & Burrowing

Chipmunks are not true hibernators. Instead they enter a torpid state, in which their body temperature and heartbeat decrease, but they wake every few days to feed on stockpiled food and to defecate.

In Massachusetts, they enter their burrows in late October and, except briefly during warm spells, they do not emerge until March or April.

A chipmunk's burrow system is quite amazing. They dig an entrance hole 1½ to 2 inches diameter leading to a working tunnel 10 to 30 feet deep. Off the tunnel they excavate chambers for sleeping, storing food, defecating, and giving birth.

Once the chambers have been completed the chipmunk uses dirt to plug the working tunnel and makes a new entrance hole that lacks a mound of dirt. As a result, the new entrance, which is usually located under stonewalls, fallen trees or rocks, goes unseen by predators.

Situations & Solutions

Chipmunks pose no real threat to people, but they can disrupt the garden and occasionally enter the home. Find out your options