Most of the day they stay in their nest or lie on a limb or other platform where they sleep and sun themselves. By comparison, fox squirrels come out later and retire earlier and are frequently more active in the middle of the day. Gray squirrels are more wary than fox squirrels and thus are regarded by most sportsmen as harder to hunt. The importance of acorn and nut crops is shown by the drastic fluctuations in squirrel numbers following years of good or bad mast production. These staple, winter foods have an important influence on the physical condition of the females which must produce next year's young.
Squirrels are notorious because of their habit of buying nuts in the ground.
Stored nuts have no particular ownership, and the members of a squirrel community share each other's efforts. The general position of stored food probably is located slightly by a sense of memory, but the actual position of individual nuts is found by a keen sense of smell. Many buried nuts are not recovered, and a large percentage of them sprout and eventually become trees. The mating period for gray squirrels begins in late December or early January while fox squirrels tend to start breeding 10 days to two weeks earlier. Another general mating period occurs from late May to early July.