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Activity

Gray squirrels are crepuscular (active at dawn and dusk) in spring, summer, and autumn, but are active only in midday in winter. These squirrels may be especially active in fall, when nuts are available and squirrels cache food items. However, squirrel sightings may also relate to changes in population size. Young squirrels disperse from spring through fall, usually traveling no more than two miles from their birthplace. Gray squirrels are not territorial, but may defend the immediate area around a nest site.

Red squirrels are active during the daytime, but may rest up during intense midday heat. In severe winter weather, they may remain inactive in their nests. Juveniles establish home ranges on or adjacent to that of their mother. They are territorial and defend their areas against other red squirrels.

Breeding & Offspring

Gray squirrels use both leaf nests and natural cavities for shelter and for rearing of the young. Leaf nests are most commonly constructed in hardwoods; cavities in live trees are preferred over those in snags. Gray squirrels usually breed at about 10-14 months of age. Usually, yearlings have only one litter per year. Adults may breed twice annually, depending on food availability. Winter breeding occurs in January-February, and summer breeding from May to July. The 2-3 feeble young are born after a 44-45 day gestation period and are weaned at 8-10 weeks. 

Red squirrels tend to prefer tree leaf nests over cavities, but sometimes use rock dens and burrows. Age at first breeding is 10-12 months. Red squirrels typically have a single litter (2 are rare), with 1-7 young born during March-May after a 31-35 day gestation period. The young are weaned at 7-8 weeks.

Habitat

Gray squirrels are typically found in extensive mature hardwood forests—especially oak-hickory — often with dense understory vegetation. They are found less often in coniferous forests. Gray squirrels are tolerant of human presence and often live in urban or suburban areas with large mature shade trees. Red squirrels are found primarily in coniferous forests—pine, spruce, or fir—with mature trees preferred over low-growth ones. In suburban areas, they are often found in small pine plantations or woodlots, interspersed with some hardwoods.

Foods

Gray squirrels have diverse diets and feed on those items which are seasonally available. However, nut crops, such as oak acorns, hickory nuts, beechnuts, and walnuts, may comprise ¾ of their annual diet. Berries, fruits, seeds, buds, and flowers, as well as cultivated grains, are also eaten. Animal foods are infrequently consumed. Red squirrels are opportunistic, but most commonly feed on conifer seeds. In the northeastern states, piles of cone fragments are often found directly under feeding perches, rather than heaped in "middens" as occurs in the west. Red squirrels also eat fungi, buds, and the inner bark of trees. They also occasionally eat nuts and seeds, fruits and grains, and insect larvae and bird nestlings.