Eastern Chipmunk Overview
Chipmunks are small ground dwelling rodents. They are common from Quebec south to Florida and west to Louisiana and North Dakota. Chipmunks have characteristic markings that make them easy to distinguish from other members of the squirrel family. Two white stripes, one above and one below the eye, adorn the short, round head. Five black lines stripe the back: two on each side, separated by a white or buff band which contains the fifth black stripe down the middle of the back. The ears are short, rounded and held erect. The flattened tail is well-haired, blackish above, rust below, and fringed in white or gray. Both sexes are alike in color and size, being 8 1/2 to 9 1/2 inches long and weighing 2 1/2 to 4 ounces. Their front feet are adapted for holding and eating food while sitting upright. The front teeth are chisel-shaped, a characteristic of all rodents.
Chipmunks inhabit deciduous (hardwood) forests where there is a thick vegetative understory and old logs or stone ledges. In open stands with little or no cover, chipmunks are most often found on rocky hillsides and living in crevices of stone walls. They are frequently seen in parks and around gardens and lawns.
Chipmunks seem more common than other members of the rodent order because they are diurnal (active during the day). Most activity, however, takes place during the cooler hours of the morning and afternoon. Excessive heat and inclement weather will hamper normal activities. These rodents are highly aggressive toward intruders, and readily defend the immediate area around their den entrance. Their defense is more vocal than violent. You have probably heard the chipmunk’s loud “chuck, chuck, chuck” call.
Chipmunks are omnivorous, feeding on plant and animal material. Acorns, beechnuts, seeds of woody plants, berries of American Yew, ragweed, wintergreen, Canada mayflower, clover and wild buckwheat are among the major plant foods consumed. Sometimes mushrooms, sunflower seeds, watermelon, apples and squash are also eaten. Animal food consists of insects, worms, salamanders and occasionally star-nosed moles, young mice, small songbirds and frogs. Chipmunks have specially adapted internal cheek pouches which allow them to carry large amounts of food at one time. These pouches are used when caching (to conceal or hide for future use) food for winter consumption and are emptied by squeezing them with their front feet. On occasion, they eat food on the spot, often at a favorite stump or rock which becomes littered with broken nut shells and fruit seeds. Much time is spent in late summer and fall gathering and storing nuts and other seeds for the winter.
When not occupied with food-gathering or territorial defense, chipmunks sleep in their underground burrows. Burrow entrances are neat round holes, usually two inches or less in diameter. They are often located under a rotten log, stump or rock. From the entrance, the burrow plunges straight down for a few inches and then descends more gradually until it levels out at a depth of about three feet. During burrow excavation, soil is carried away from the entrance in cheek pouches used to carry food. Because of this, there is little or no evidence of excavated material from the subterranean burrow system. Within four or five years, an average chipmunk’s burrow may be extended to a length of thirty feet, have several openings, and may contain up to six chambers. In late October or November, chipmunks retire to their dens, plugging up the entrance hole. Although they are not true hibernators, some may sleep for long periods of time during the cold winter months. They store food rather than fat and must wake up often to eat. Mild weather during mid-winter may entice them out of their dens for short periods of time.
Chipmunks emerge to breed in late February and early March. There are two breeding seasons annually: spring and summer. During the spring season, the older females, yearlings and females born the previous summer season will breed. During the summer season, late July to August, yearlings who did not mate in spring and a few of the three-month-old females may also breed. Older females may produce two litters per year. Most young are sexually mature at one year old. After a 31-day gestation period, four or five (from one to eight) young are born. Young chipmunks are blind and naked at birth. They spend a month in the burrow system before leaving the den.
Chipmunks rarely climb trees except to escape from predators, or to gather food. They spend almost all of their entire lives in an area usually less than a half-acre, and often no more than 12, 000 square feet. Travel of 75 yards or greater from the den would be considered exceptional. The outer fringes of individual home ranges often overlap with other chipmunks. Except during the breeding season, chipmunks are solitary, living in separate dens. Predators of chipmunks include man, hawks, mink, raccoons, weasels, martens, foxes, bobcats, coyotes, red squirrels, cats and large snakes.
In their natural habitat, chipmunks compete with and complement the natural community of plants and animals. They compete with gray, red and flying squirrels, grouse, deer, turkeys, mice and other mast (acorn, beechnut and other forest nuts) eating animals for food. When excessive amounts of food are stored and left in the ground there is perhaps less for other wildlife, but forest tree species are regenerated when these stored seeds sprout. Chipmunks on occasion prey on bird’s eggs or nestlings.
Chipmunks are enjoyable to watch, but when they move into urban settings they may conflict with man’s interest. They dig up garden seeds and have been accused of snitching flower bulbs. Chipmunks get into camps and homes on occasion and can cause limited structural damage. Burrow entrances in lawns, rock gardens, stone walls and near foundations may also be objectionable. In many instances, however, any disturbance is offset by the pleasing antics of these alert animals.