Squirrels and Relatives: Sciuridae

Most squirrels are active during the day, yet some species, such as all the flying squirrels, are nocturnal, active at night. Squirrels communicate by making shrill sounds. They also communicate by tail gestures, such as "flicking" the tail to indicate that another squirrel should go away. Most squirrels wrap their tail around themselves when resting. Squirrels build nests high in the trees called dreys, which are made of twigs and leaves. They line the inside of dreys with fur, feathers, or other soft material. The nest typically will have two exits. Squirrels also will build a nest called a den in the hollow of a tree.

Flying squirrels do not actually fly, as bats and birds do—they leap and glide. They leap from a high point, flattening their bodies and extending the legs widely, and then land at a lower point. Some species can glide for as much as 1,476 feet (450 meters). The squirrels can even turn at a right angle to avoid a branch.

Ground squirrels make burrows, tunnels or holes, which they use to rest in during the heat of the day and escape predators, animals hunting them for food. Many of the ground squirrels hibernate, become inactive to conserve energy, for varying periods of time. Some squirrels can hibernate for up to nine months.

Tree squirrels are solitary animals, yet some African species travel in pairs or small groups. These squirrels build nests of leaves or needles in hollow trees or limbs. They are active and maneuver (mah-NOO-ver) easily in trees.

For ground squirrels, the breeding season follows shortly after hibernation. Some species will skip a year of breeding; others can reproduce more than once a year. Baby ground squirrels are generally born underground without fur. There are usually four in a liter. Flying squirrels typically give birth to small litters of one to two offspring, which are generally blind and naked at birth. Tree squirrels generally have a polygamous (puh-LIH-guh-mus) mating system, meaning the male and female can have more than one mate. Litter sizes vary, depending upon the habitat and food availability.