There are two common species of tree squirrels in the Illinois area, the fox squirrel and the gray squirrel. The fox squirrels are larger than the gray squirrels and have a red underside. Gray squirrels have a white underside. Squirrels usually nest in the trees. They will use holes in the trees or make a nest out of leaves high up in the branches.
Squirrels have litters of 3-5 young twice a year. Fox squirrels are born between April and May and again between August and September. Gray squirrels are born between February and April and again between August and September. Gestation is 38 days long in fox squirrels and 44 days in gray squirrels. The eyes open in 28-35 days and the squirrels are weaned at 6-8 weeks. They leave the nest between 10 and 12 weeks of age.
Squirrels body temperature is 98-102 degrees.
If you have found a squirrel in need, please refer to our Wildlife Help and Resources page: https://vetmed.illinois.edu/wildlife/wildlife-help-and-resources/squirrels/