The red squirrel, Tamiasciurus hudsonicus, is a widespread and active arboreal rodent across much of North America. These squirrels inhabit diverse forest environments, including coniferous, deciduous, and mixed woodlands. They are readily recognized by their rusty-olive fur, often with a white underside and a distinctive dark stripe along their sides during summer. Their lively habits and persistent chatter frequently make them conspicuous residents of the forest canopy.
Litter Size and Breeding Season
Red squirrels typically have one or two litters each year, influenced by their geographic location and resource availability. Breeding activity often commences in late winter or early spring, around February or March, with a potential second breeding period in the summer, usually in August. Litter size typically ranges from one to eight young, with three to five being most common. Following successful mating, the gestation period for a female red squirrel averages between 35 and 40 days. Females are receptive to mating for only a single day during each breeding cycle, during which multiple males may compete. The male red squirrel plays no part in raising the young after mating.
Growth and Care of Kits
Red squirrel kits are born in a highly dependent state, blind, hairless, and weighing approximately 10 to 18 grams. They remain entirely reliant on their mother for warmth, nourishment, and protection within the nest, known as a drey. These dreys are often constructed in tree cavities or as large, spherical masses of twigs, leaves, and moss, providing a secure haven. The mother cares for her young, nursing them and, if disturbed, may move them to an alternative drey.
Kits undergo rapid development within the nest; skin pigment appears and the first hairs emerge around 14 days, with full fur growth by about three weeks. Their eyes and ears typically open between three and four weeks of age. They begin venturing outside the drey around seven weeks old, starting to explore their surroundings and experiment with solid foods. Weaning occurs between seven and ten weeks, and by approximately 18 weeks of age, the young squirrels become independent and disperse from their natal territory.
Factors Affecting Reproductive Success
The reproductive success of red squirrels is influenced by a combination of environmental and biological factors. Food availability, particularly the abundance of conifer cones, plays a substantial role. In years with plentiful cone crops, known as mast years, females are more likely to produce two litters and may have larger litter sizes. Climate conditions also affect breeding; harsh winters can reduce the overall health of squirrels, impacting their ability to breed successfully. Spring temperatures can have lasting positive effects on a female’s reproductive success.
Population density can also influence outcomes, with higher densities sometimes leading to lower survival rates among squirrels. Healthier mothers generally produce heavier kits, which have better survival prospects.