The Arctic fox preys on many small creatures such as lemmings, voles, ringed seal pups, fish, waterfowl, and seabirds.

Arctic foxes form monogamous pairs during the breeding season and they stay together to raise their young in complex underground dens.

[16] To prevent heat loss, the Arctic fox curls up tightly tucking its legs and head under its body and behind its furry tail.

These are complex systems of tunnels covering as much as 1,000 m2 (11,000 sq ft) and are often in eskers, long ridges of sedimentary material deposited in formerly glaciated regions.

[19] Arctic foxes tend to select dens that are easily accessible with many entrances, and that are clear from snow and ice making it easier to burrow in.

The white fox's reproduction rates reflect the lemming population density, which cyclically fluctuates every 3–5 years.

When predators and prey are abundant, Arctic foxes are more likely to be promiscuous (exhibited in both males and females) and display more complex social structures.

Larger packs of foxes consisting of breeding or non-breeding males or females can guard a single territory more proficiently to increase pup survival.

On the coasts of Svalbard, the frequency of complex social structures is larger than inland foxes that remain monogamous due to food availability.

The older offspring (1-year-olds) often remain within their parent's territory even though predators are absent and there are fewer resources, which may indicate kin selection in the fox.

[15] Arctic foxes generally eat any small animal they can find, including lemmings, voles, other rodents, hares, birds, eggs, fish, and carrion.

They scavenge on carcasses left by larger predators such as wolves and polar bears, and in times of scarcity also eat their feces.

In some locations in northern Canada, a high seasonal abundance of migrating birds that breed in the area may provide an important food source.

During April and May, the Arctic fox also preys on ringed seal pups when the young animals are confined to a snow den and are relatively helpless.

[21] This fox is a significant bird-egg predator, consuming eggs of all except the largest tundra bird species.

Transcriptome sequencing has identified two genes that are under positive selection: Glycolipid transfer protein domain containing 1 (GLTPD1) and V-akt murine thymoma viral oncogene homolog 2 (AKT2).

The Arctic fox decreases its BMR via metabolic depression in the winter to conserve fat storage and minimize energy requirements.

One way that Arctic foxes regulate their body temperature is by utilizing a countercurrent heat exchange in the blood of their legs.

[16] Arctic foxes can constantly keep their feet above the tissue freezing point (−1 °C (30 °F)) when standing on cold substrates without losing mobility or feeling pain.

They do this by increasing vasodilation and blood flow to a capillary rete in the pad surface, which is in direct contact with the snow rather than the entire foot.

They selectively vasoconstrict blood vessels in the center of the foot pad, which conserves energy and minimizes heat loss.

By using stable carbon and oxygen isotope analysis of fossils, researchers claim that the Tibetan Plateau experienced tundra-like conditions during the Pliocene and harbored cold-adapted mammals that later spread to North America and Eurasia during the Pleistocene Epoch (2.6 million-11,700 years ago).

[45] Its range during the last ice age was much more extensive than it is now, and fossil remains of the Arctic fox have been found over much of northern Europe and Siberia.

[46] In July 2019, the Norwegian Polar Institute reported the story of a yearling female which was fitted with a GPS tracking device and then released by their researchers on the east coast of Spitsbergen in the Svalbard group of islands.

[47] The young fox crossed the polar ice from the islands to Greenland in 21 days, a distance of 1,512 km (940 mi).

She then moved on to Ellesmere Island in northern Canada, covering a total recorded distance of 3,506 km (2,179 mi) in 76 days, before her GPS tracker stopped working.

[1] However, the Scandinavian mainland population is acutely endangered, despite being legally protected from hunting and persecution for several decades.

The program was successful in terms of increasing the population of blue foxes, but their predation of Aleutian Canada geese conflicted with the goal of preserving that species.

As with many other game species, the best sources of historical and large-scale population data are hunting bag records and questionnaires.

Even after local lemming peaks, the Arctic fox population tends to collapse back to levels dangerously close to nonviability.