FLYING SQUIRREL

New World flying squirrel (Glaucomys) any member of two distinct groups of rodents that are able to make gliding leaps by means of the parachute-like membranes connected on each side to their forelegs and hind legs. The North American and Eurasian flying squirrels form one group, the subfamily Petauristinae of the squirrel family, Sciuridae (order Rodentia). The scaly-tailed flying squirrels are African rodents of an entirely different family, Anomaluridae. There are about 12 genera and 35 species of flying squirrels in the family Sciuridae. Slender, long-limbed forest dwellers, these squirrels have soft fur and large eyes and are 8 to 60 cm (3 to 24 inches) in length, exclusive of the long, often flattened, tail. They live in trees, usually nest in tree holes, and feed on nuts, fruit, other plant material, and insects. They seldom descend to the ground. Unlike other squirrels, they are nocturnal. The gliding membranes of these squirrels are furry flaps of skin and muscle. Rods of cartilage at the wrists serve to spread the membranes. In flying, the squirrels leap spread-eagled and use their outstretched gliding membranes for gliding and their bushy tails for guidance. Glides of 60 m (almost 200 feet) or more from one tree to another have been recorded. There are two species of gliding sciurids in North America and one that reaches eastern Europe; all others are Asian. The two North American species, known as New World flying squirrels (Glaucomys), are reddish or grayish brown and are 21 to 37 cm long, including the 8- to 18-centimetre tail. They are gregarious animals that nest at times in birdhouses or buildings. Pteromys volans, a species of Old World flying squirrel, is long-haired, silvery or grayish, and 10 to 20 cm long excluding the 10- to 15-centimetre tail; it occurs throughout the coniferous forests of Eurasia. Exclusively Asian flying squirrels include the large, brown or black, giant flying squirrels (Petaurista); the long-haired, gray-brown woolly flying squirrel (Eupetaurus, or Hylopetes, cinereus); and the grayish to reddish brown or black Indo-Malaysian flying squirrels (Hylopetes). Africa's scaly-tailed flying squirrels, or scaletails, are placed in 4 genera and about 12 species, all but one of which, the flightless scaletail (Zenkerella insignis), possess gliding membranes. The membranes differ from those of the sciurids in being attached to a cartilage rod at the elbow instead of the wrist. Rows of scales on the underside of their tufted tails aid these squirrels in climbing and in clinging to trees after a glide. Scaletails are similar to sciurids in appearance and are about 10 to 40 cm long without the tail. They live in tree hollows and feed on both plant material and insects. With the possible exception of the nongliding, flightless scaletail, they are nocturnal.