Chipmunks are part of the squirrel family, although their habits are nothing like their larger, grey cousins. There are 21 varieties of chipmunks in North America, but they all sleep in underground burrows. Chipmunks hibernate during the winter months, although they don't sleep the whole time as most hibernators do.
Home Sweet Home
Chipmunks are very busy during the warmer months. They like to live in forested areas with low-growing plants, which offer protection from predators. During the summer, they build their nests in underground burrows, where they sleep and spend the winter. The chipmunk's elaborate burrow consists of a long, underground tunnel with numerous entrances and rooms. They carry plant matter such as grass and leaves to furnish their sleeping quarters, and construct extra rooms to store food for the winter.
Furnishing the House
A chipmunk burrow is an architectural marvel. It can be as much as 30 feet long and 3 feet deep. It consists of two levels -- the first, a shallow tunnel closer to ground level, and a deeper burrow with additional rooms and storage space. Chipmunks nap during the day between foraging in the shallow tunnel, with easy access to the outside. The deeper burrow is used for storing winter food, overnight sleeping and hibernation. It is well lined with plant matter to keep them warm. Chipmunk burrows are usually located on a slope to provide water drainage. Once completed, a chipmunk removes the fresh dirt from the openings in the ground to keep predators from finding them.
The Long Winter's Nap
Chipmunks start to prepare for the winter in July, eating extra seeds and nuts to pack on additional fat. They spend the next few months carrying seeds and nuts to the winter burrow, where it's stored to see them through the cold weather. They retreat to their deep burrow in late October, occasionally emerging on warm days. Chipmunks are not true hibernators whose bodies remain inactive for the winter months. A chipmunk wakes periodically to eat from his food stash. While asleep though, a chipmunk's body is in hibernation mode. His temperature drops, and his heartbeat and breathing slow. He curls into a small ball and can sleep up to several weeks at a time.
A Solitary Sleeper
Chipmunks sleep alone. Although they mate twice a year, in spring and late summer, females raise litters alone after one month's gestation and the young depart the nest at 4 to 6 weeks of age to live solitary lives. There is no bonding between mates or litters. A female chipmunk has her babies in the deep section of her own burrow, where she builds a nest. She continues to live there when the young leave to build burrows and find their own territory, often close to where they were born.