The Arctic Fox (Vulpes lagopus) thrives across the challenging, circumpolar environment of the tundra. Its diet adapts to the severe seasonal fluctuations of its habitat. This small canine maintains a crucial position in the Arctic food web. The fox’s survival strategy relies on a flexible approach, shifting between active hunting and opportunistic scavenging to utilize available resources.
The Arctic Fox’s Primary Prey Base
The foundation of the Arctic Fox’s diet consists overwhelmingly of small rodents, particularly lemmings and voles. These small mammals are the primary energy source in the tundra ecosystem, and the foxes’ reproductive success is directly tied to their population cycles. Lemming numbers typically fluctuate on a three-to-five-year cycle, causing a corresponding boom-and-bust pattern in the fox population. When lemmings are abundant, a single female fox can give birth to a very large litter, sometimes exceeding 15 pups.
During the warmer months, the diet diversifies significantly, incorporating the eggs and chicks of ground-nesting birds. Foxes denning near coastal cliffs will rely heavily on seabirds like murres and puffins during the nesting season. This influx of protein and fat is important for raising litters and building up necessary fat reserves. The fox is an adept hunter, possessing an acute sense of hearing that allows it to locate and pounce on rodents moving in tunnels beneath the snowpack, even in deep winter.
Clarifying the Role of Squirrels in the Diet
Whether the Arctic Fox eats squirrels depends on the specific species and region. Common tree squirrels found in temperate forests do not inhabit the high Arctic tundra. However, the Arctic Ground Squirrel (Urocitellus parryii) is a native resident across parts of the fox’s range in North America and Siberia.
This ground squirrel is a secondary, yet important, prey item when available, often being a larger meal than a lemming. Arctic Ground Squirrels are targeted by foxes during the brief summer period when they are active above ground and emerging from hibernation. They are not a consistent dietary staple like lemmings, as they spend much of the year hibernating deep underground. When a fox successfully hunts an Arctic Ground Squirrel, it provides a substantial caloric boost, contributing significantly to the accumulation of fat before winter.
Seasonal Scavenging and Opportunistic Feeding
When the small rodent population crashes or winter limits hunting success, the Arctic Fox relies on opportunistic scavenging. Foxes frequently follow larger predators, such as polar bears, onto the sea ice to feed on seal carcasses. This behavior allows the fox to consume high-fat marine mammal carrion it could not obtain independently.
Along the coast, the fox utilizes marine resources, including washed-up fish, invertebrates, and seaweed. To prepare for periods of scarcity, the animals cache surplus catches of eggs or rodents in their dens. This stored food is retrieved later, helping the fox maintain its energy balance during the dark, cold months.