Arctic Fox (Vulpes lagopus): Facts, Winter Coat and Habitat

What does an Arctic fox look like?

The Arctic fox is round and compact rather than slim. Its muzzle is short, its ears are small and rounded, and its legs are short, all features that reduce the amount of skin exposed to the cold. The tail is long and very bushy, and even the soles of the feet are covered in dense fur in winter. That furry foot gives the species its scientific name: lagopus comes from the Greek for “hare foot”.

Two genetically distinct color forms, or morphs, occur in the wild:

• White morph: brown or gray-brown on the back with a paler belly in summer, and almost pure white in winter. About 90% of the world’s Arctic foxes are this type, and it dominates on the mainland tundra.
• Blue morph: dark brown, charcoal or bluish-gray in summer, becoming only a little lighter in winter. It is most common on coasts and islands, especially in Iceland, where it makes up the majority of foxes.

Both morphs can occur in the same litter. Arctic foxes molt twice a year, and the winter coat is about twice as long as the summer coat. Read more in why Arctic foxes change color.

How big is an Arctic fox?

The Arctic fox is smaller than the familiar red fox and about the size of a large house cat, though it looks bigger in its fluffy winter coat. Males are larger than females, and body size varies between populations.

Weight also changes through the year. In autumn an Arctic fox can put on more than 50% of its body weight as fat, which it then slowly burns during the winter.

Habitat and range

The Arctic fox has a circumpolar range, which means it lives all the way around the North Pole. It is found on the tundra of northern Alaska and Canada, in Greenland, Iceland, Svalbard, the mountains of Norway, Sweden and Finland, and across northern Russia, including many Arctic islands. In Canada it reaches south to Hudson Bay and in places into the northern edge of the boreal forest.

Its main habitat is treeless Arctic and alpine tundra, often near the coast. It is also at home on rocky shores and on the frozen sea, and it has been seen on sea ice close to the North Pole. The Arctic fox is the only land mammal native to Iceland, which it reached at the end of the last ice age by walking across the frozen sea. During the ice age itself it lived much farther south, and its fossils are found across much of northern Europe.

Long journeys across the sea ice

Most Arctic foxes stay in a home range for much of their lives, but some make extraordinary journeys, especially when lemmings are scarce. The best-documented record comes from a young female fitted with a satellite collar by the Norwegian Polar Institute on Svalbard in 2018. She crossed the sea ice to Greenland, a distance of about 1,512 km (940 mi), in 21 days, then kept going to Ellesmere Island in Canada.

In total she covered about 3,506 km (2,179 mi) in 76 days, averaging around 46 km (29 mi) a day and up to 155 km (96 mi) in a single day. Journeys like this explain how Arctic foxes reached remote islands and why populations around the Arctic are genetically well mixed. They also depend on sea ice, which is shrinking as the Arctic warms.

How does the Arctic fox survive the cold?

The Arctic fox’s winter fur is among the best insulation of any mammal. About 70% of it is fine, dense underfur that traps a thick layer of still air next to the skin. Its rounded body, short ears and short muzzle give it a small surface area for its size, so less heat escapes.

Its feet have a special trick. Blood vessels in the legs work as a countercurrent heat exchanger: warm blood flowing down to the feet passes close to cold blood returning to the body and warms it, so little heat is wasted. The footpads are kept just above the temperature at which tissue would freeze, about −1 °C (30 °F), even when the fox stands on snow far colder than that.

In bad weather an Arctic fox curls up tightly with its nose and legs tucked under its thick tail, shelters in a den or digs into a snowbank. It also lowers its energy needs in winter by moving less and slowing its metabolism. Find out more in how Arctic foxes survive the cold.

What do Arctic foxes eat?

The Arctic fox is mainly a meat-eater and a scavenger that will eat almost any small animal it can catch or find. Inland, its staple foods are lemmings and voles. It can hear a lemming moving under the snow, then leaps high and punches down through the snow with its front feet to pin it. A family of foxes can eat dozens of lemmings a day when lemmings are plentiful.

On coasts and islands it eats seabirds and their eggs, fish, shellfish and other marine invertebrates, and in spring it digs ringed seal pups out of their snow lairs on the sea ice. In winter many Arctic foxes follow polar bears across the ice to scavenge the remains of their seal kills, and they also feed on reindeer and other carcasses. Berries and seaweed add a little plant food.

In summer, when food is abundant, the fox stores the surplus. It buries eggs, lemmings and young birds in caches, which it can still eat months later. Read the full story in what Arctic foxes eat.

Behavior and family life

Arctic foxes are active day and night, and they do not hibernate. Outside the breeding season they are mostly solitary, but pairs usually defend a shared territory around their den. They communicate with barks, screams and yelps, and they mark their territory with scent.

Arctic fox dens are impressive. They are dug into sandy ridges, mounds and slopes where the ground does not stay frozen, and the largest can cover hundreds of square meters, with dozens of entrances. Good dens are reused by generation after generation of foxes for decades and, by some estimates, for centuries. The foxes’ droppings and food scraps fertilize the soil, so old dens often stand out as unusually green patches on the tundra.

Reproduction and life cycle

Arctic foxes are mostly monogamous, and both parents help raise the young. Mating takes place in spring, mainly in April and May, and the pups are born after a pregnancy of about 52 days, usually in May or June. The pups weigh only 60–90 g (2–3 oz) at birth and are blind and deaf for the first two weeks.

Litter size depends on food. Inland foxes that rely on lemmings have small litters or skip breeding in years when lemming numbers crash, but when lemmings are at a peak a litter can contain 10 to 18 pups or more. Litters of more than 20 have been reported, the largest of any member of the order Carnivora. Coastal foxes, which have a steadier food supply, usually raise about five or six pups each year.

The pups first leave the den at three to four weeks old and are weaned at about seven weeks. They become independent in late summer or autumn, and they can breed when they are about ten months old. Sometimes a young female from the previous year stays with her parents and helps raise the next litter.

Lifespan, predators and threats

Life is short for most wild Arctic foxes. Many die in their first year, and those that reach adulthood typically live three to four years, with a few reaching about 11. In captivity they can live up to about 16 years.

Predators include golden eagles and other large birds of prey, snowy owls (which take pups), wolves, wolverines, brown bears and polar bears. The polar bear is both a danger and a source of food. The larger red fox is an important competitor: where its range spreads north, it takes over the best dens and kills Arctic foxes and their pups. Starvation in years when prey is scarce, disease such as rabies and mange, and climate change are other threats.

Conservation status

The Arctic fox is listed as Least Concern on the IUCN Red List (last assessed in 2014), with a stable overall population that is thought to number several hundred thousand animals. Numbers rise and fall with the lemming cycle, which peaks roughly every three to five years.

Some local populations are in serious trouble. In mainland Norway, Sweden and Finland, heavy hunting for fur in the early 20th century left only a few dozen to a couple of hundred adults, and the species is still nationally threatened there despite legal protection since the 1920s to 1940s. Captive breeding, releases and supplementary feeding have helped it recover to several hundred animals. On Mednyi Island in Russia’s Commander Islands, an ear mite infection introduced with dogs cut the local population by about 85–90% in the 1970s. See are Arctic foxes endangered? for the details.

Arctic foxes and people

For centuries Arctic foxes were trapped for their fur, and the dark “blue fox” pelts were especially valuable. Fur farmers released foxes onto dozens of islands in Alaska’s Aleutian chain in the late 19th and early 20th centuries, where they devastated nesting seabirds. Wildlife managers have since removed them from many of those islands, and seabird numbers have recovered.

Today Arctic foxes are a favorite of wildlife watchers in Iceland, Svalbard and the Canadian Arctic. Around towns and research stations some become quite bold. They should still be watched from a distance and never fed, both for the foxes’ sake and because Arctic foxes can carry rabies in parts of their range.