Foxes are adaptable animals that remain active throughout the winter, a time when many other creatures hibernate or migrate. Their ability to thrive in cold environments showcases specialized behaviors and physical characteristics, allowing them to navigate challenging conditions.
Adapting to the Cold
Foxes possess physical adaptations to withstand low temperatures. Before winter, they develop a thicker coat, often twice as dense as their summer fur, providing insulation. This winter coat consists of two layers: coarse guard hairs protect from elements like snow and rain, and a dense underfur traps air close to the body, minimizing heat loss. Some foxes, like the Arctic fox, also grow fur on their footpads for insulation and traction on snow and ice.
Foxes do not hibernate; instead, they adjust daily routines to conserve energy. When resting, a fox curls into a tight ball, wrapping its bushy tail around its body and nose to reduce heat loss. This posture, combined with their dense fur, helps maintain a stable body temperature even in freezing conditions. Some species, like the Arctic fox, have a more compact body shape, with shorter muzzles and ears, to minimize surface area and reduce heat dissipation.
Physiological mechanisms also contribute to their winter survival. Foxes build up a layer of fat during autumn, serving as both insulation and an energy reserve when food is scarce. Some foxes have a countercurrent heat exchange system in their legs. This system allows warm arterial blood from the heart to transfer heat to cooler venous blood returning from the paws, minimizing heat loss from extremities in contact with cold surfaces.
Finding Food in Winter
Locating food becomes more challenging for foxes during winter due to snow cover and reduced prey activity. Their diet includes small mammals like mice, voles, rabbits, and squirrels, as well as birds and carrion. Foxes are opportunistic foragers and scavenge for food, sometimes venturing closer to human settlements where sources might be more accessible.
To find prey hidden under snow, foxes rely on acute senses of hearing and smell. They can detect subtle movements of rodents beneath several feet of snow. Once a fox pinpoints its prey, it employs a distinctive hunting technique known as the “mouse pounce.”
During a mouse pounce, the fox listens intently, then leaps high into the air, plunging headfirst into the snow to capture unseen prey. This acrobatic maneuver is a common and effective strategy for catching small animals like lemmings and voles. The technique requires precision and practice, and foxes may attempt it multiple times before a successful catch.
Winter Denning and Mating
Foxes utilize dens throughout the winter, primarily for shelter from harsh weather and for raising their young. While they often curl up in the open, severe storms or the need for a protected space drive them to seek refuge in burrows, hollow logs, or abandoned badger setts. A vixen may dig a new den or occupy an existing one.
Winter is the mating season for foxes. For many species, mating occurs from late December through February. During this period, both male and female foxes become more vocal.
Vocalizations, such as the vixen’s distinctive scream, are common during courtship and serve to attract mates and warn off rivals. Male foxes also use barks and scent marking to announce their presence and territorial claims. After successful mating, the gestation period for red foxes is around 52 days. The female prepares for the arrival of her kits, born in early spring, by lining the den with grass and fur.