Most active during the day, the American red squirrel feeds mainly on seeds, conifer cones and nuts, but will also take a variety of other items including fruits, buds, bark, flowers, fungi, and even insects, birds’ eggs and small vertebrates, such as nestling birds and mice (2) (3) (5) (6) (8). It has also been recorded biting into maple trees to feed on the sugary sap, and at some times of year will strip bark to feed on the underlying tissues (2) (3) (6). In some areas, the American red squirrel gathers cones into a few large ‘middens’, usually located in hollow stumps or under logs, which serve as central larders during poor conditions. Each midden may contain 2,000 to 4,000, or even up to an incredible 18,000 cones, and may be used by several generations. The American red squirrel is more territorial than most other North American squirrels, vigorously defending an area around the middens. Contrary to the popular misconception, the species does not hibernate, instead becoming inactive for short periods during bad weather, and taking shelter in a nest located in a tree hole, an underground cavity, or in a loosely constructed ball of sticks and vegetation in a tree (2) (3) (5) (6) (8).
The American red squirrel usually breeds from February to April, sometimes with a second litter from June to August (1) (2) (3) (5). The female may mate with several males, the potential suitors actively pursuing oestrus females in a conspicuous ‘mating chase’ that may last several hours (3) (5) (6) (8). The female gives birth to an average of 3 to 5 young, after a gestation period of 31 to 35 days. Born naked and helpless, the young squirrels are weaned by 7 to 8 weeks, and become independent by around 18 weeks, reaching sexual maturity by about a year old (2) (3) (5) (6). The female will sometimes relinquish all or part of the territory to one or more juveniles, and move away to establish a new one, giving the young squirrels a greater chance at becoming territory holders (3) (5). The American red squirrel may live for up to ten years in the wild, although average lifespan rarely exceeds around three to seven years (2) (3) (5) (6).