The Arctic Fox (Alopex lagopus) lives year-round in the circumpolar North, a landscape characterized by extreme cold and dramatic seasonal shifts in resource availability. This small canid has developed a highly flexible and varied diet to ensure its survival on the treeless tundra. The fox is classified as an opportunistic predator, relying on whatever sustenance is available in its harsh environment. This dietary flexibility allows the species to maintain a foothold in a region where resources can become inaccessible or disappear entirely for long stretches of the year.
The Core Diet: Small Mammals and Birds
The summer months, when the tundra is briefly thawed and teeming with life, represent a period of abundance for the Arctic Fox, allowing it to rely on a core diet of small mammals and ground-nesting birds. The foundational food source for most inland fox populations is the lemming, a small rodent whose population cycles directly influence the reproductive success of the foxes. In years when lemming and vole populations boom, a single fox family may consume dozens of these small prey items daily, leading to larger litter sizes and higher survival rates for the pups.
Beyond these primary rodents, the Arctic Fox capitalizes on the seasonal influx of migratory birds that arrive to nest on the tundra. The fox raids bird colonies, consuming the eggs and chicks of species like snow geese, ptarmigan, and various seabirds. Coastal fox populations, sometimes referred to as ‘blue foxes,’ may also hunt seabirds such as puffins and murres near cliffside rookeries, integrating these protein-rich foods into their summer menu. This seasonal reliance on live prey is crucial for building the fat reserves necessary to endure the long Arctic winter.
Winter Survival Strategies and Scavenging
The arrival of the long, dark Arctic winter forces a dramatic shift in the fox’s feeding habits, as the snowpack covers most small mammals and migratory birds depart. With live prey sources scarce, the fox transitions from an active predator to a resourceful scavenger, a strategy that minimizes energy expenditure in the extreme cold. This often involves traversing vast distances, with foxes sometimes traveling hundreds of miles across the frozen sea ice in search of sustenance.
A primary winter strategy involves following larger predators, like polar bears and wolves, to scavenge the leftovers of their kills (carrion). By trailing these hunters, the fox accesses the remains of large marine mammals, such as seal carcasses, which provide a substantial, calorie-dense meal impossible to secure alone. Coastal foxes may also supplement their winter diet by foraging along the shoreline for marine resources, including seaweed, washed-up fish, or dead invertebrates. This is supplemented by the utilization of food caches, which the fox buried during the summer and autumn, allowing it to retrieve and consume frozen provisions during the leanest months.
Specialized Hunting Techniques
Even when live prey is hidden beneath snow and ice, the Arctic Fox possesses specialized techniques to locate and capture small mammals. The most distinctive of these methods is known as “mousing,” a high-energy pouncing action used primarily to catch lemmings and voles moving through the subnivean layer beneath the snow. The process begins with the fox utilizing its acute sense of hearing, which is sensitive enough to detect the faint rustling or digging of a rodent moving below the surface.
Once the prey’s location is precisely pinpointed, the fox executes a sudden, vertical leap, sometimes several feet into the air. It then plunges headfirst, nose-diving into the snow crust to break through the surface and ambush the prey below. This powerful, targeted strike uses the fox’s body weight and momentum, making it effective at reaching the tunnels and burrows where lemmings shelter.