<P> Eastern gray squirrels build a type of nest, known as a drey, in the forks of trees, consisting mainly of dry leaves and twigs . The dreys are roughly spherical, about 30 ~ 60 cm in diameter and are usually insulated with moss, thistledown, dried grass, and feathers to reduce heat loss . Males and females may share the same nest for short times during the breeding season, and during cold winter spells . Squirrels may share a drey to stay warm . They may also nest in the attic or exterior walls of a house, where they may be regarded as pests, as well as fire hazards due to their habit of gnawing on electrical cables . In addition, squirrels may inhabit a permanent tree den hollowed out in the trunk or a large branch of a tree . </P> <P> Eastern gray squirrels are crepuscular, or more active during the early and late hours of the day, and tend to avoid the heat in the middle of a summer day . They do not hibernate . </P> <P> Predators include humans, hawks, weasels, raccoons, foxes, domestic and feral cats, snakes, owls, and dogs . In its introduced range in South Africa, it has been preyed on by African harrier - hawks . </P> <P> Eastern gray squirrels can breed twice a year, but younger and less experienced mothers normally have a single litter per year in the spring . Depending on forage availability, older and more experienced females may breed again in summer . In a year of abundant food, 36% of females bear two litters, but none will do so in a year of poor food . Their breeding seasons are December to February and May to June, though this is slightly delayed in more northern latitudes . The first litter is born in February or March, the second in June or July, though, again, bearing may be advanced or delayed by a few weeks depending on climate, temperature, and forage availability . In any given breeding season, an average of 61--66% of females bear young . If a female fails to conceive or loses her young to unusually cold weather or predation, she re-enters estrus and has a later litter . 5 days before a female enters estrus, she may attract up to 34 males from up to 500 meters away . Eastern gray squirrels exhibit a form of polygyny, in which the competing males will form a hierarchy of dominance, and the female will mate with multiple males depending on the hierarchy established . </P>

Where did the eastern gray squirrel come from