Forest Preserve District of Cook County, Illinois
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Nature Bulletin, No. 5  March 10, 1945
Forest Preserve District of Cook County
Clayton F. Smith, President
Roberts Mann, Superintendent of Conservation

Take a good look at the next squirrel you see. Watch him come, head- first, down a tree; and notice that his hind legs have a sort of swivel joint at the ankle so that his sharp-clawed feet can be turned completely around. Notice the tiny button "thumbs" between which he holds the bit of food he eats. Notice that his eyes, like those of rabbits and other vegetable-eaters, are placed at the sides of his head so that he can watch for his enemies: the cats and hawks. Compare them with the forward-looking eyes of the meat-eaters such as the cat, the dog, the hawk and man himself.

The squirrel's tail is his most noticeable and perhaps his most useful possession. Few animals have a tail with so many practical uses. The squirrel is the gossip of the woods and with flicks of his tail he punctuates all that he has to say. His tail serves as a parachute in his daring leaps and to break the rare, accidental falls; also as a balancer when he runs along a narrow branch. It is both his blanket and his sunshade.

The squirrel's teeth are also highly specialized and designed for the kind of food he eats. He belongs to the very numerous "chisel-tooth" tribe known as the RODENTS, which includes the rats, beaver, porcupine and others, whose front teeth consist of two incisors in the upper jaw and two in the lower. (Incisor is from a Latin word meaning "to cut"). These teeth have a fine, sharp, chisel edge suited for gnawing through nutshells, grains, seeds and other hard vegetable material. They never stop growing. Only constant use keeps them short and sharp. A lack of hard nuts or other material upon which to gnaw, prevents this wearing down and the teeth become so long that they cannot eat. The teeth of pet squirrels can be clipped; otherwise they may actually die of starvation.

Nuts, seeds, wild fruit and berries are a large part of the diet of squirrels. In winter, much of their diet is made up of hibernating insects and their larvae found under the bark of trees; also the juicy buds of trees. But squirrels bury food in the ground, in preparation for winter; one nut or acorn or seed in each hole. During the winter they seem to locate these stores by smell, and dig them up.

Squirrels prefer a winter den in a hollow tree but occasionally find an opening and make their home just beneath the roof of a house or barn. Occasionally, where no suitable den can be found, a pair of squirrels will build a "dray" or nest of twigs and leaves, lined for winter with leaves or shredded bark. In the early spring four to six young are born, naked and blind. For ten weeks they are dependent upon their mother's milk. Not until they are weaned do their tails fluff out, and only then are they ready to venture into the world. The whole family usually moves to summer home or "dray" built of green leaves, in order to escape from the soiled and flea ridden den. By summer or early fall, the young are ready to shift for themselves and the mother may raise a second family.

There are two kinds of squirrels in the forest preserves: the fox squirrel and the gray squirrel. The little red squirrel, or chickaree, is no longer found in Cook County but can be found in the Indiana Dunes State Park. The fox squirrel is the more common of the two, being found all over the country wherever there are trees. They have yellowish faces and yellowish underparts; their backs are covered with reddish-brown fur tipped with gray. The gray squirrels are smaller, have whitish or light gray faces and underparts darker gray backs, and are found more in the north and northwestern parts of the county. The two kinds are quite different in temperament and each has its own kind of calls an.

Chatter. Squirrels have a very small home range and may spend their entire lives within an area no larger than five acres -- often much smaller. Some squirrels attain an age of from 6 to 10 years.

The bite of a squirrel is NOT poisonous but, like any small, deep wound that is difficult to clean and sterilize, it may become infected. In some parts of the country, rabies has been found in squirrels as it has been found in coyotes and other wild animals., but it has never been found in squirrels in this part of Illinois.

Bob Becker, outdoor sports-writer, has reported this winter that numerous gray squirrels in the north shore suburbs show signs of a bad mange epidemic. The Illinois Natural History Survey has observed the same condition on fox squirrels in other parts of the state. The Survey naturalists say this is not mange and not a disease, but an infection called "scabies". It is due to a skin parasite known as mites and is most common among old, weakened animals. It is more common in cities where dens and proper food are more scarce than in the country, and where there are so few natural enemies that the squirrel population tends to grow too large. It also is apt to be more common after severe winters such as this one, probably because the squirrels are weakened by prolonged scarcity of food and by having to stay inactive in their dens.

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