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Squirrel. A rodent mammal with a bushy, hairy tail. In America the squirrel family is divided into three groups - the marmots, the flying squirrels, and the true squirrels. The marmots include the woodchucks and prairie dogs (q. v.). The flying squirrel is a nocturnal animal with a body about five inches long, and a flat tail of about four inches covered, like the body, with short, fine, silky hair. It has a thin flap of skin attached between the fore and hind legs. This it uses like a parachute, leaping from a tree and sailing downward to another. The true squirrels are divided into the tree squirrels, the rock squirrels, and the ground squirrels, according to their mode of living. The tree squirrels are mostly arboreal, living either in hollow trees or building spherical nests on the branches. The gray squirrel is typical of this group. As the name indicates, it is grayish, or iron-grayish, all the back, and the tail is fringed with white. From tip of nose to tip of tail its length is eighteen inches. The black squirrel is considered a variety of the gray and is similar in size and habits. In some parts of the United States the black variety is more numerous than the gray. The fox squirrels are larger than the grays, having a length of twenty-three to twenty-five inches. The body is iron gray and the tail fringed with brown. In the southern fox squirrel the tail is fringed with black and the nose and ears are white. The red squirrel is reddish-brown on the back and white on the belly. It is smaller than those described and a destroyer of bird eggs and young. The rock squirrels live in rocks, stone piles, and fence corners. The chipmunk is the type of this group. It has cheek pouches, and uses them to gather and store up grain and nuts for the winter. The ground squirrels burrow in the earth and store their food in their burrows. They live mostly on grain, and from this fact are known as spermophiles, or "seed lovers". They are most numerous west of the Mississippi. Nearly all the squirrels are eaten as food, and the skins of some species have some commercial importance as fur.