The gray squirrel is smaller and appears sleeker than the fox squirrel. Litters contain as few as one or as many as five kits, but females normally produce two or three young. Another breeding season may occur in early summer. Squirrels Depend on Dens Gray squirrels and fox squirrels occupy a range where winter storms may be severe, and both species bear their first annual litter of young in early spring. Therefore, suitable dens are important as nesting sites.
Natural dens are generally cavities that form when mature trees shed dead limbs.
In time, the exposed wood at the location of the wound begins to rot. Eventually a hollow forms in the main branch or trunk. These cavities, which may take many years to form, protect squirrels from severe weather and predators and furnish sheltered nest sites for the female and her young. There are many localities that are potential squirrel habitats if only den trees were available. A close look at your area may reveal one or more of the following situations where squirrel populations are limited by the scarcity of trees with suitable natural nesting cavities.