The second litter is usually born in July. The nest is often in a tree cavity or constructed of leaves suspended in the treetops. These leaf nests are also used for temporary protection against inclement weather or predators. They have keen senses of sight, smell, and hearing and are alert, nervous and wary, especially on the ground. When danger is near, they quickly retreat to the safety of the trees.
Gray squirrels are somewhat sociable and can tolerate other squirrels nearby.
The gray squirrel is active year-round but needs tree cavities for shelter during harsh weather. In the fall, gray squirrels gather and bury, at random, a winter food supply. This food supply is usually recovered as needed, by sniffing the ground until a buried nut is found. In a few years, populations of gray squirrels can change dramatically. During successive years of good acorn production, squirrel populations may reach high levels.