The arctic fox (Alopax lagopus) is a member of the canid family and is related to other foxes (such as the red fox species of the Denali area,) and wolves and dogs. Found throughout the arctic circumpolar lands, in Alaska its range extends from along the arctic and Bering seacoasts as far south as the Aleutian Islands.
The white phase of fox predominates in the north and on St. Lawrence and Nunivak islands but on the Pribilof and Aleutian islands, where arctic foxes have been introduced, the blue colored type favored by fox farmers predominates. Both color phases may occur in the same litter.
The arctic fox is about the size of a large cat, between 30 to 45 inches in length, weighing 6 to 10 pounds and standing about 9 to 12 inches at the shoulder. The tail of the fox, making up 35 percent of the animals length, looks large in comparison to the body.
Over the winter the arctic fox has a heavy white coat, but when early summer temperatures begin to melt the snow cover, the coat is shed for a thinner, two-tone brown pelage. White fur not only provides camouflage in winter but adds warmth. A pigment called melanin, absent in white fur, gives the fox its brown summer coat. The hair shafts of white fur are hollow, trapping warm air from the animals body heat and acting as insulation much the same way as a down coat does for a human wearer. Snowshoe hares, polar bears, ermine and ptarmigan all similarly benefit from their winter white coats. The small proportion of this fax species which is the blue color phase in winter sheds its coat in spring to a thinner and darker bluish-gray in summer.
The wide distribution of this fox in such a severe arctic environment is testament to its superb adaptation to cold and to the wide variety of food it will eat. The compact body form, short snout and short, rounded, well-furred ears minimize heat loss from body extremities. The deep, thick pelage of very fine hair, and the hair on the soles of their feet provide excellent insulation. Even in winter, arctic foxes seldom seek shelter during their incessant search for food, except during severe storms when they may dig a hole in a snow bank or search out a breeding den.
The diet of the arctic fox is extremely varied throughout its range, related as it is to regional geographic characteristics and seasonal fluctuations in food supply. Microtine rodents, such as lemmings, ground squirrels and voles are an important component of the diet. A characteristic of the lemming cycle, the crash, a decrease in population, has a major impact on arctic fox numbers and may force them to abandon customary hunting areas to travel hundreds of miles in a nomadic search for food. Foxes inhabiting marine regions also hunt for small marine animals, fish and carrion along shorelines. During summer, nesting and other adult birds, eggs and flightless young also make up a large part of the foxs diet. In winter, coastal arctic foxes venture onto the sea ice where they frequently trail polar bears to feed on the remains of seal kills.
About two months before the end of winter, arctic foxes begin to pair up and mate. The pairs remain together at their den site throughout the 51 to 57 days of gestation. Dens are usually made in sandy ridges of well-drained, river-bank soil and may be used year after year. Litters of arctic foxes are born between late May and early June and average 7 to 10 kits. Both parents help raise the young and may hunt up to 19 hours a day to feed their large litters. By fall the youngsters can fend for themselves and the family unit breaks up.