The eastern chipmunk, Tamias striatus, is one of 25 species of chipmunks, all but one are found in North America and the eastern chipmunk, the largest, is the only one found in Connecticut. The Siberian chipmunk, Eutamias sibiricus, is found in Asia.
When you think of chipmunks how can you not remember “Alvin and the Chipmunks”. “The Chipmunks” – Alvin, Simon, and Theodore, along with their human adoptive father David Seville, became famous first in records in 1958 and then in animated cartoons and eventually movies and videos. Real chipmunks don’t sing like Alvin and his brothers, but they are extremely vocal. Eastern chipmunks give three calls – chipping, chucking and trilling. The chipping and chucking are repeated calls that seem to be calls back and forth to each other. Trilling is done to “sound the alarm” when a predator gets too close.
Eastern chipmunks are reddish-brown in color and they have five black stripes on their back. One black stripe runs down the middle of the back. Two black stripes run down either side of their backs with a white stripe between them. There are also light stripes above and below the eyes.
Chipmunks live primarily in deciduous forests, generally maple-beech forests, but they will occupy bushy areas or coniferous forests. They are omnivores and the food they eat varies seasonally. In warmer months they will feed on insects, mushrooms, berries, frogs, small mammals like young mice and even birds and their eggs. They will cache, or store, a variety of seeds, nuts and acorns underground so they have plenty of food for the winter. By hoarding these tree seeds they help to establish tree seedlings. Their genus, Tamias, means “treasurer”, “steward” or “housekeeper” in reference to this role in plant dispersal. Chipmunks are in the Squirrel Family along with woodchucks, prairie dogs, ground squirrels and tree squirrels.
Chipmunks are wonderfully adapted to carrying large amounts of food down into their elaborate dens. As gnawing mammals in the Order Rodentia (rodents) they have two incisors in the upper jaw and two in the lower. Then there is a distinct space, no canine teeth, between the incisors and the grinding teeth (premolars and molars). They have 20 teeth, quite a bit fewer than the opossum that has 50 teeth! In addition to the space between the teeth they have flexible, rubbery pouches that can stretch three times the size of their head. One video showed them able to stuff 6 acorns in their mouths at one time.
Their complex dens may be up to 30 feet long with several rooms and 4-5 entrances. They remove the soil from around the entrances so not to alert predators to the den. Each room has a special use – one for nesting, one for sleeping quarters that is clear of shells, another for food storage and an area for feces. The nests are made of crushed leaves.
The eastern chipmunk will mate twice a year – February to April and again June to August. The male (buck) defends their territory during mating season. The gestation is one month and the female (doe) gives birth to a litter of 2-6 babies (kits, kittens or pups). The babies are blind, hairless and helpless and weigh about 3 grams, the size of a bumblebee. The female cares for the young and they remain underground about six-weeks, becoming independent and dispersing from the nest at about two months of age. Their home range is only about 100 yards. An adult eastern chipmunk weighs 2-5 ounces and measure 8-10 inches with the tail included. Like most rodents they have four toes on their front feet and five toes on the hind feet.
Chipmunks do not have fat reserves for hibernation so instead they store food and wake-up to eat throughout the winter. Once asleep their heart rate and breathing slow down and their temperature falls. Their heartbeat drops from 350 beats per minute, when they are active, to 4 beats per minute while sleeping. Their temperature goes from 95-105.8o F to 41-44o F.
Chipmunks are active during the day, diurnal, and a common sign of a chipmunk are “middens”. When chipmunks eat they sit on a fallen log, stump or rock and they leave the remains of what they have eaten – acorn shells or hemlock cones.
Some people think of chipmunks as a nuisance since they feed on plants and flower bulbs, raid birdfeeders, burrow in the ground or enter into garages or basements. They in turn are a food source of hawks, foxes, coyotes, weasels and snakes and are preyed upon by domestic cats. So I guess it is a balance – chipmunks help to establish forests and disperse the spores of mushrooms, so if they eat a few flowers and a handful of sunflowers, or perhaps take up residence in your backyard, or just provide some outdoor entertainment as they scurry across the stonewall – not so bad, I think we make out better in the long run! And besides…they are so darn cute!
Wildlife Fact Sheet – Chipmunk
Nature on PBS – Chipmunk Showdown YouTube Video 2:31
Tracking & the Art of Seeing – How to Read Animal Track & Signs by Paul Rezendes
Britannica – Chipmunk