The Arctic fox (Alopex lagopus) occurs in two color morphs: white and blue. White foxes have a pure white winter coat, which turns brownish-gray on the back and white on the belly in summer. The blue morph is usually brownish-blue in winter and uniform blue-black in summer. Arctic foxes have long been prized for their winter fur for clothing by Greenlandic and Canadian Inuit, Saami, and Russian indigenous peoples, and early traders encouraged native peoples to trap foxes for the luxury European market. They are still of economic importance to the human inhabitants of the Arctic. Arctic foxes are called Teriangniaq qaqortaq (white color) and Teriangiaq qernertaq (blue color) in Greenlandic, Polarr^v in Danish (also Hvidr&v for the white form; Blar&v for the blue form), Refir in Icelandic, Fjellrev or Polarrev in Norwegian, Fjallrav in Swedish, Napakettu in Finnish (also Naali for the white form; Sinikettu for the blue), and pesets in Russian.

The Arctic fox belongs to the dog family, Canidae, and is the only species in the genus Alopex. They are among the smallest canids, normally weighing between 2.5 and 4.0 kg. Arctic foxes seldom survive for more than three to four years under natural conditions. However, the oldest ever reported was 13 years old.

The Arctic fox is circumpolar in distribution, living above the treeline in alpine areas in Fennoscandia, on the tundra mainland of Arctic Eurasia and North America, and on islands in the Arctic, North Atlantic, and North Pacific oceans. It also ranges widely over pack ice. The Arctic fox lives in two main habitat types, inland and coast, which offer differences in both diet and reproductive patterns. In inland tundra regions, Arctic foxes are food specialists or semispe-cialists relying on cyclic small rodent populations that fluctuate with a periodicity of three to five years. Such unpredictable environments, in terms of prey

availability, provide wide variation between years in litter sizes. Foxes living on islands or near the sea close to bird cliffs are generalists, preying on food both from the marine and the terrestrial food web. This provides a more predictable and stable food supply and the foxes produce relatively few cubs every year.

Arctic foxes are territorial in the breeding season, with home range sizes from 3 km2 (coast) to 60 km2 (inland), but can switch to a more nomadic behavior during winter, presumably in search for food. They are known to move great distances during such seasonal migrations, more than 1000 km in one season. Migrating Arctic foxes can penetrate deep into the taiga and cross vast tracts of pack ice. Information based on ear-tag return shows that Arctic foxes are able to travel from Western Alaska to Eastern Canada, from Siberia to Alaska, and from Svalbard to Novaya Zemlya. It has also been reported that mass migrations can take place between northeast Canada and Greenland, and within the Russian Arctic. Mass migrations usually take place after peak production years in Arctic foxes and their small rodent prey.

Arctic foxes, considered to be generally or sequentially monogamous, can start breeding in their first year of life, but they are then not as successful as older foxes. The females enter estrus once a year and mating occurs in March or early April. Litters are born after a gestation period of 52 days (i.e., in late May or early June). The Arctic fox litter size is among the largest in the order Carnivora; the greatest number of cubs ever reported is 22. Inland Arctic fox populations have a mean litter size of seven with maximum 13, while coastal foxes have a mean litter size of five and maximum seven.

The population biology of the Arctic fox in most inland tundra regions is dominated by large fluctuations in numbers, caused by and synchronized with the three- to five-year cyclical fluctuations in small rodents that are their main prey. The world population of Arctic foxes is thought to be in the order of several hundred thousand animals. The total trapping harvest for North America has been about 40,000 animals annually, with up to 85,000 during peak years from 1919 to 1987. The number of live animals in the Russian Arctic was estimated before 1985 to be around 50,000 during a low and more than 400,000 in peak years. Arctic foxes in Iceland were a threat to sheep and lamb farming and were subject to intense persecution from the late 13th century. In the year 2000, the calculated minimum population size was just over 6000, having recovered more than fourfold in 20 years (Pall Hersteinsson, personal communication). However, in Fennoscandia, intensive hunting at the end of the 19th and in the early 20th centuries resulted in near extinction of the Arctic fox populations. Despite total protection in all Fennoscandian countries since 1940, the population has not recovered and is now endangered.

Arctic foxes are opportunistic generalist predators, but can also function as a specialist on fluctuating small rodent populations in most inland areas. Along the coast and near bird cliffs, food is available, in excess, during the breeding season, but is restricted during winter. Thus the coastal habitats provide a stable and predictable environment. In spring and summer, coastal foxes are ringed seal pup predators; they also prey on birds and feed on eggs, marine mammal carcasses, marine and freshwater fishes, marine and terrestrial invertebrates, and carcasses of reindeer or other large mammals. Winter diet is mainly ptarmigan and the carcasses of large mammals. Some Arctic foxes feed on remnants of seals killed by polar bears on the sea ice. In inland habitats, the main prey species in summer are lemmings (mainly Lemmus and Dicrostonyx spp.) and voles (mainly Microtus), and also carcasses of reindeer and other large mammals, while in winter, the most important food resources are large mammal carcasses and ptarmigans. Arctic foxes also store excess food gathered by caching during spring and summer, for use in late autumn and winter.

The most important predators for the Arctic fox, especially the cubs, and competitors for food are red fox (Vulpes vulpes), wolf (Canis lupus), wolverine (Guio gulo L.), snowy owl (Nyctea artica), golden eagle (Aquila chrysaetos L.), and white-tailed eagle (Haliaeatus albicilla L.).

Due to their long-range migrations, Arctic foxes are likely to be transmitters and important carriers of diseases and parasites affecting humans. Rabies is widespread throughout the Arctic region and is enzootic with the Arctic fox both as a reservoir species and the main vector of the disease in the Arctic. The tapeworm, Echinococcus multilocularis, uses the Arctic fox as a definitive host (i.e., the host harbors all developing stages as well as the egg-laying adults). This parasite causes the disease alveolar echinococcosis in humans that is often fatal, with mortality rates as high as 80% or 90% in untreated cases.

In Scandinavian countries, foxes were believed to cause the northern lights (aurora borealis). The Eskimos have a legend about the parentless mistreated boy, Kagssagssuk, who obtain superhuman strength from the "Master of Strength," who appears like a big fox with a long tail. The folklore of many cultures, such as the Inuit, Siberian people, and native North Americans, tells stories about the fox's ability to shape-shift into a human being, usually an attractive young woman.

Eva Fuglei

See also Fur Trade; Trapping Further Reading

Eberhardt, Lester E. & Wayne C. Hanson, "Long-distance movements of Arctic foxes tagged in northern Alaska." Canadian Field Naturalist, 92 (1978): 386-389 Garrot, Robert A. & Lester E. Eberhardt, "Arctic Fox." In Wild Furbearer Management and Conservation in North America, edited by Milan Novak, James A. Baker, Martyn E. Obbard & Bruce Malloch, Ontario: Ontario Trappers Association, Ministry of Natural Resources, 1987, pp. 394-406

Grambo, Rebecca L., The World of the Fox, San Francisco: Sierra Club Books, 1995

Hersteinsson, Pall & David W. Macdonald, "Interspecific competition and the geographical distribution of red and Arctic foxes Vulpes vulpes and Alopex lagopus'.' Oikos, 64 (1992): 505-515

Hersteinsson, Pall, Karl Frafjord & Asko Kaikusalo, "The Arctic fox in Fennoscandia and Iceland: management problems." Biological Conservation, 49 (1989): 67-81

Macpherson, A.H., "The dynamics of Canadian Arctic fox populations." Canadian Wildlife Service Report Series, 8 (1969): 1-49

Wiklund, Christer G., Anders Angerbjorn, Erik Isakson, Nils Kjellen & Magnus Tannerfeldt, "Lemming predators on the Siberian tundra." Ambio, 28 (1999): 281-286

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