The Arctic Fox (\(Vulpes lagopus\)) is a resilient predator suited to the harsh, treeless tundra environment across the circumpolar North. This small canid, which is about the size of a large house cat, endures temperatures that can drop below -50°C. Its survival relies on a highly flexible, opportunistic diet, making it a generalist feeder rather than a specialist hunter. The Arctic Fox must adapt its foraging habits to the extreme seasonal variation in food availability.
The Foundational Diet: Lemmings, Voles, and Hares
The diet of the Arctic Fox is built upon rodents, primarily lemmings and tundra voles. These mammals are high-calorie prey that form the backbone of the fox’s hunting efforts, especially during the summer months. A single family of Arctic Foxes can consume dozens of lemmings each day when the rodents are abundant. This heavy reliance means that fox population dynamics are closely linked to the cyclical nature of lemming populations, which often peak every three to five years.
Arctic Foxes do consume Arctic Hares. However, hares are significantly larger and faster than lemmings, making them more difficult and energetically costly to catch. Hares are considered a secondary prey item, hunted successfully when other food sources are scarce or where hare populations are dense. For the Arctic Fox, the consistent, easy-to-catch lemming represents a much more reliable energy source than the solitary hare.
Seasonal Adaptations and Opportunistic Scavenging
The Arctic Fox employs a shift in its diet to combat the scarcity of the long winter season. During the brief summer, the diet diversifies, incorporating bird prey such as eggs and young chicks from ground-nesting species like geese and seabirds. An Arctic Fox living near a dense goose colony may cache up to 90% of the eggs it collects during the nesting season for later consumption.
Coastal populations of the Arctic Fox, often referred to as “blue foxes,” incorporate marine-based food into their regimen year-round. This includes scavenging fish, mollusks, and other invertebrates washed ashore, or preying on vulnerable ringed seal pups found in their snow dens during the spring. When animal sources become difficult to find, the foxes are omnivores and will forage for berries, seaweed, and other available plant matter on the tundra.
Scavenging larger kills is an important survival strategy during the winter, when the tundra is covered in deep snow and small prey is harder to locate. The foxes will follow large predators like polar bears or wolves to feed on the remains of seal or caribou carcasses. This behavior minimizes the energy expenditure required for hunting, allowing the fox to survive on carrion from animals it could not kill itself. In severe periods of food shortage, the fox consumes virtually any organic matter, including the feces of other animals.
Specialized Hunting and Food Acquisition Strategies
The Arctic Fox has evolved distinct behaviors and physical adaptations to acquire and secure food in its challenging environment. One of its most characteristic hunting techniques is the vertical pounce, often called “mousing,” used to capture small rodents hidden beneath the snow. The fox uses its acute hearing to pinpoint the exact location of a lemming moving in its subnivean tunnels. It then leaps several feet into the air, plunging headfirst through the snow crust to ambush the prey below.
Another strategy involves deliberately following larger predators like the polar bear out onto the sea ice. This is a calculated strategy that allows the smaller fox to exploit the bear’s successful hunting of seals. By trailing the bear at a safe distance, the fox gains access to the energy-rich blubber and meat scraps left behind, which provides vital calories for long-distance travel and survival.
Food caching is the most important strategy for surviving the lean months, allowing the fox to store resources during the summer abundance for later use. The fox digs a small hole using its forepaws, places the excess food—such as eggs or small animals—into the cavity, and then covers it with substrate using its muzzle. This stored food creates a reserve that the fox can relocate with its sense of smell during the winter.