About Chipmunks

Eastern Chipmunk with bug on nose © Aranya Karighattam
Eastern Chipmunk © Aranya Karighattam

The Eastern Chipmunk (Tamias striatus) is a member of the squirrel family in the order Rodentia. It's believed that the English word "chipmunk" was derived from "chetamnon," the name given to the animal by peoples of the Chippewa nation.

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). Most of their waking hours are spent gathering and storing food in their burrows.

Appearance

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

With a body 5-6 inches long and a tail that's 3-4 inches long, chipmunks are about 1/3 the size of an Eastern Gray Squirrel. As chipmunks scamper along the ground they hold their flat, hairy tail in the air.

Chipmunk © Colleen Bruso
© Colleen Bruso

Food

Seeds, berries, nuts, and fruit are the mainstays of a chipmunk's diet, but they also eat insects, insect larvae, slugs, snails, and earthworms. Occasionally they will even eat the eggs of small birds—such as sparrows and juncos—in addition to frogs and small snakes.

Chipmunks possess cheek pouches in which they store food before depositing it in their burrow, which will sustain them during the winter. Researchers have reported seeing a chipmunk stuff nearly 72 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, hairless, and blind young—each no more than 2.5 inches long—are born after a 31 day gestation period. The first litter is generally born in April or May, and the second in July or August.

After 6 weeks, and 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, and 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 newly-independent youngsters of occupied territory.

Chipmunk with full cheeks © Justin Miel
Chipmunk © Justin Miel

Hibernation

Chipmunks are not true hibernators. Instead they enter a torpid state during 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 again until March or April.

Burrows

A chipmunk's burrow system is quite amazing! They dig an entrance hole 2 inches in diameter down to around 2 feet, then continue digging parallel to the surface for up to 10 feet before terminating the tunnel in a sleeping chamber. They'll then excavate chambers off the tunnel for storing food, defecating, and giving birth.

Once the chambers have been completed, the chipmunk uses dirt to plug up 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 stone walls, fallen trees, or rocks—goes unseen by predators.

Situations & Solutions

Chipmunks pose no real threat to people. However, they can be quite disruptive in the garden and, occasionally, gain access to your home. What to do if you encounter a chipmunk >