In 2017, I spotted my first-of-year eastern chipmunk out and about in a maple/basswood forest on Feb. 21. In 2016, the first active one was observed Feb. 25. These animals are hibernators, yet unlike the thirteen-lined ground squirrels and woodchucks, chipmunks do not put on much pre-hibernation fat. They awaken each week or so during the winter to feed on acorns and other seeds stored in underground pantries. They sometimes even emerge during winter warm spells. But we can always expect to see some out by mid-March, the beginning of their mating season. The first litters arrive in May and the second in August.
Each male and female makes and maintains their own burrows, usually in or near woodlands where there are rocky places, stone walls, or a wood pile. Burrows are about two inches wide and have several entrances. Some are as large 10-by-5 feet, with chambers for sleeping, storing food, and waste.
Eastern chipmunks are active only during the day. Although they do climb trees, they spend most time on the ground. Adults maintain a territory around their burrows, using specific signals to indicate boundaries and avoid contact. Their most common signal is a low bark — the "munk" sound — a single note sometimes repeated over and over for as much as an hour.
Chipmunks make up for their small size with big sounds. When faced with danger, they call "chip, chip, chip," with up to 130 "chips" per minute. In the spring the sounds also serves a social function.
Jim Gilbert taught and worked as a naturalist for 50 years.