Forest Preserve District of Cook County, Illinois
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Flying Squirrels
Nature Bulletin No. 176-A   January 23, 1965
Forest Preserve District of Cook County
Seymour Simon, President
Roland F. Eisenbeis, Supt. of Conservation

Few people ever see a Flying Squirrel, although they are widely distributed throughout the wooded areas of the northern hemisphere and numerous in many localities. Unlike other squirrels, they sleep all day in their dens, coming out at dusk to feed and play during the night -- less in winter than in summer. They spend more time in the trees and less on the ground than any other squirrel. Most distinctive, of course, is their ability to glide thru the air.

Flying squirrels do not fly. On each side of the body is a loose elastic membrane or fold of skin, covered with fur and extending from the wrist of the foreleg to the ankle of the hind leg, with a delicate rod of cartilage, attached only to the wrist, at the edge. Another membrane fills the triangular space between the foreleg and the neck and sides of the head. When the animal leaps outward from a tree, it spreads its legs so that, in the flaring membranes stretched between them, it appears almost square and flat -- shape and sails diagonally downward in a long swooping glide. Its long bushy tail, broad' and flat, is used as a rudder and as a brake to make the short graceful swoop upward when it lands on another tree.

There are several kinds of flying squirrels including one that ranges across the Arctic Circle. Those common in the eastern half of the United States are smaller than elsewhere -- about the size of a small rat -- the tail making up almost half the total length of 9 inches or less. The flying squirrel in our central states may vary from tawny gray to pinkish cinnamon above, with white underparts. Its thick silky fur is as soft as velvet. Like other squirrels it has a blunt-faced head and small rounded ears, but the unusual feature is a pair of great black eyes which enable it to see exceptionally well at night and probably make daylight distasteful. Like all tree dwellers, it has hand-like feet with long flexible toes and sharp strong claws. Apparently, the only sound it utters is a faint squeak.

Flying squirrels usually live in hollow trees or abandoned woodpecker holes, but they will build summer nests of leaves, and they occasionally take over an empty bird house near a residence, or find their way into an attic where they become a nuisance because, after dark, a flying squirrel becomes a frolicsome bundle of energy. In winter, 20 or 30 may band together in a single den. Returning to his cabin in spring, one forest ranger found the chimney plugged with leaves and shredded bark, another nest in the stove, and four nests in his mattress.

They feed mostly on seeds, tree buds, nuts, fruits and insects. One pair, that came every night to capture moths and beetles at a lighted window, were finally tamed and had their young indoors, although they came and went as they pleased. These two would eat meat, just as in the wild they may eat the eggs or young of birds. Owls are their chief enemies, although foxes and weasels sometimes catch them on the ground. They have from 2 to 6 young in a litter but observers differ as to whether they may have two or only one litter per year.

Virginia Moe, in ANIMAL INN, her fascinating book about the many and various animals at Trailside Museum in the Forest Preserve District, says that the young -- born naked and blind -- open their eyes and are well furred all over when they are about 3 weeks old. They grow swiftly after that. Miss Moe says they seem to sleep harder than most animals and when roused in the daytime their drooping eyelids give them the sleepiest look ever seen on an animal's face. They also play harder than other animals but never tussle or quarrel with each other, even when feeding. As pets they are unrivaled: soft and sleek; sociable and sweet-tempered; mischievous and tirelessly playful at night.

The flying squirrel is the cherub of the animal kingdom.

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