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

****:FLYING SQUIRRELS

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.