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

****:SQUIRRELS

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 and

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.