The Arctic fox, Vulpes lagopus, is a small canid adapted to survive the extreme temperatures and scarcity of the circumpolar Arctic tundra. Its ability to thrive is tied to its highly flexible and opportunistic feeding habits. The diet shifts constantly to capitalize on whatever food resources become available, allowing the fox to persist through long winters and brief, resource-rich summers.
The Foundation of the Diet: Small Mammals
Inland populations of the Arctic fox rely overwhelmingly on microtine rodents, which form the energetic backbone of their diet, particularly lemmings and voles. A single family of foxes can consume dozens of these small mammals daily during the summer when raising young. The availability of lemmings is so important that the fox population’s reproductive success is intrinsically linked to the rodent’s boom-and-bust cycle.
Lemming populations undergo fluctuations, typically peaking every three to five years. During a peak year, a female Arctic fox can produce exceptionally large litters, sometimes numbering up to 18 pups, taking advantage of the temporary food surplus. Conversely, when the lemming population crashes, foxes often do not reproduce at all, demonstrating their dependence on this single prey source.
To capture these rodents, which often tunnel beneath the snowpack, the fox employs a technique known as “mousing” or “pouncing.” The fox uses its acute hearing to pinpoint the prey’s location, then leaps high into the air, diving headfirst into the snow at speeds of two to four meters per second to surprise and capture the animal below.
Marine Resources and Scavenging Opportunities
When small rodents are scarce, the Arctic fox turns to larger, unpredictable food sources, often relying on scavenging rather than active hunting. Scavenging is a strategy most often seen in winter, involving following larger carnivores like polar bears onto the sea ice. The fox then feeds on the remains of seal carcasses, such as ringed or bearded seals, left behind after a successful hunt.
Along coastlines, the diet diversifies further to include marine resources and seasonal prey. Foxes patrol the shore for stranded marine life, fish, and invertebrates washed up by the tides. During spring (April to May), they actively prey on vulnerable ringed seal pups confined to their birth lairs within the snow. Summer brings an abundance of avian prey, with foxes consuming adult birds (such as ptarmigan and waterfowl), eggs, and chicks during the nesting season.
Seasonal Shifts in Foraging Strategy
The Arctic fox’s foraging behavior undergoes a complete shift between the short summer and the long winter to match seasonal changes in resource availability. Summer is a period of intense activity and resource accumulation when breeding and raising pups require massive caloric intake from abundant lemmings and nesting birds. During this time, the fox exhibits strong food-caching behavior, burying excess prey in permafrost dens to preserve it for later use.
As winter approaches and the tundra is blanketed in deep snow, the fox shifts from a territorial hunter to a nomadic scavenger. Many individuals migrate significant distances, sometimes traveling thousands of miles, to follow the receding sea ice or track coastal areas where scavenging is more likely. The fox relies heavily on stored body fat, which provides a substantial energy reserve, and its cached food stores to survive the deep cold. This reliance on behavioral and metabolic adaptations allows the Arctic fox to navigate periods of extreme scarcity until summer abundance returns.