The arrival of winter often prompts a common question about backyard wildlife: where do squirrels go when temperatures drop and snow covers the ground? These small mammals, a familiar sight throughout much of the year, seem to vanish from the landscape during colder months. This apparent disappearance leads many to wonder about their strategies for enduring the season.
Winter Retreats
Squirrels utilize different shelters during winter, depending on whether they are tree squirrels or ground squirrels. Tree squirrels, such as grey squirrels, red squirrels, and fox squirrels, primarily seek refuge in nests known as dreys or within natural tree cavities. Dreys are spherical structures built in tree forks, composed of woven branches and insulated with leaves, moss, and other plant materials. The interior of a drey can be significantly warmer than the outside air. Tree squirrels also use existing tree hollows or abandoned woodpecker holes, which offer protection from predators and harsh weather.
Ground squirrels, including chipmunks and groundhogs, adopt a different approach, relying on underground burrows for winter survival. These burrows provide stable temperatures below the frost line, offering protection from extreme cold. Ground squirrel burrows can be extensive, up to 30 feet long and 4 feet deep. Chipmunk burrows, while smaller, also feature elaborate tunnel systems with multiple chambers for nesting and food storage. These homes are lined with insulating materials like leaves and grasses, creating a warm environment.
Winter Activity and Survival
Squirrels employ various strategies to survive the colder months, which differ by species. Most tree squirrels do not truly hibernate; instead, they enter periods of torpor, a state of reduced metabolic activity where heart rate, breathing, and body temperature decrease, conserving energy. They can easily awaken and emerge on warmer winter days to forage. In contrast, many ground squirrel species undergo true hibernation, a prolonged dormancy where their body temperature and metabolic rate drop drastically. Some ground squirrels may hibernate for months, occasionally waking to forage.
A primary survival mechanism for both types of squirrels is their reliance on cached food, typically nuts and seeds, buried during warmer months. They scatter-hoard these food items in numerous locations, often selecting spots near landmarks. Squirrels locate these hidden caches even under snow using keen spatial memory and an acute sense of smell. They can detect the scent of buried nuts through layers of snow. Opportunistic foraging also occurs, with squirrels consuming available bark, tree buds, or insects when other food is scarce.
Squirrels exhibit both physiological and behavioral adaptations to cope with cold. Physiologically, they grow a thicker, denser winter coat, which provides insulation by trapping heat. They also accumulate body fat during fall by consuming high-calorie foods, serving as an energy reserve and additional insulation. Behaviorally, tree squirrels reduce activity, spending more time in their nests during severe cold, and may huddle together in dreys with other squirrels for warmth. Shivering is another tactic squirrels use to generate heat.