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Tree Squirrels

Three species of tree squirrels occur in Winnebago County. All are small mammals characterized by a long, bushy tail, prominent ears, and long hind feet. None of the tree squirrels hibernate, but they do have periods of reduced activity during severe cold weather.

Fox squirrel

(Sciurus niger)

The fox squirrel is the largest tree squirrel in Illinois, weighing one and three-quarters to two pounds with a length of 19 ½ to 22 inches. The fur is a mix of rusty-yellow with black with an overall reddish cast. The fur on the ears, belly, and edge of the tail is lighter.

Eastern gray squirrel

(Sciurus carolinensis)

The gray squirrel typically weighs 1 and a quarter pound with a length of 17 ¼ to 18 ¼ inches. The fur is gray on the back and white to light gray on the belly. Melanistic (black) or albinistic (white) variants occur in Illinois.

Fox and eastern gray squirrels prefer to nest in tree cavities but will build nests out of leaves if necessary. They have two breeding seasons, one in winter and one in late spring or early summer. Females under 2 have one litter a year; older females, two. Litters consist of two, three or four young, which stay near the female until the next litter is born.

Southern flying squirrel

(Glaucomys volans)

The southern flying squirrel is the smallest tree squirrel in Illinois weighing approximately two ounces with a length of eight and five eighths to nine and three quarters inches. The fur is glossy gray to cinnamon on the back and white on the belly. The eyes are large and the tail is flattened. This squirrel appears larger than it is because of the folds of skin on either side of the body that extend from the wrist to the ankle. This feature gives the squirrel its gliding capability. 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.These uncommon squirrels often nest in dead trees.