The Arctic fox (Vulpes lagopus) is a highly adaptable predator that thrives in the extreme conditions of the circumpolar Arctic region. Known for its thick fur and compact body, which minimize heat loss, this species is well-suited to frigid temperatures that can drop to -50°C (-58°F). Its survival in such a challenging environment relies significantly on a flexible and opportunistic diet, allowing it to exploit various food sources throughout the year.
Primary Prey
The diet of the Arctic fox primarily consists of small mammals, particularly lemmings and voles, which form the bulk of their food intake during summer months. Lemmings are so fundamental to the Arctic fox’s survival that fox populations often fluctuate in direct response to cyclical changes in lemming numbers. These rodent populations typically experience boom-and-bust cycles every three to five years, directly impacting the foxes’ reproductive success. During years of high lemming abundance, a female Arctic fox can produce large litters, sometimes up to 15 pups, to capitalize on the plentiful food supply.
When lemming populations are low, the Arctic fox must diversify its diet to include other small rodents and hares. The availability of these primary prey animals is a major determinant of the fox’s success in inland tundra ecosystems. In coastal areas, where lemmings might be less prevalent or fluctuate less dramatically, foxes may rely more on seabirds and their eggs as a consistent food source.
Seasonal Adaptations in Diet
The Arctic fox’s diet changes with the seasons, reflecting the availability of different food sources. During the summer, when primary prey like lemmings and voles are abundant, the foxes also consume birds, their eggs, and chicks. Coastal populations frequently prey on nesting seabirds, including auklets, puffins, and murres, and may also consume fish and marine invertebrates. Berries and seaweed can also supplement their diet when other animal prey is less available.
As winter approaches and primary prey becomes scarcer, the Arctic fox demonstrates remarkable opportunism and a shift towards scavenging. They often follow larger predators, such as polar bears, onto the sea ice to feed on the remains of seal carcasses or other kills. This scavenging behavior provides a significant source of protein during the lean winter months. In some low lemming years, marine resources can constitute a large proportion of their winter diet.
Foraging Behaviors and Survival
Arctic foxes employ various clever techniques to acquire food and ensure their survival in the challenging Arctic landscape. Their acute senses of smell and hearing are particularly valuable, enabling them to detect small mammals moving beneath layers of snow. Once prey is pinpointed, the fox uses a unique pouncing technique, often called “mousing,” where it leaps high into the air and dives headfirst into the snow to capture its hidden meal. The fox’s elongated snout is adapted to penetrate snow with minimal resistance, reducing the risk of injury during these forceful dives.
Beyond active hunting, Arctic foxes are adept scavengers, resourceful enough to follow polar bears for miles in anticipation of leftover carcasses. A significant survival strategy is food caching; when food is plentiful, especially during the summer, they bury surplus prey like eggs or small mammals in shallow holes or rock crevices. These caches are then remembered and utilized during periods of scarcity, demonstrating an important foresight in managing food resources for long-term survival.