Arctic fox (Vulpes lagopus)

Also known as: Polar fox
Synonyms: Alopex lagopus
  
French: Isatis, Renard Polaire, Reynard Polaire
Spanish: Zorro Ártico
KingdomAnimalia
PhylumChordata
ClassMammalia
OrderCarnivora
FamilyCanidae
GenusVulpes (1)
SizeHead-body length: 46 – 68 cm (2)
Shoulder height: 28 cm (2)
Weight1.4 – 9 kg (2)

The Arctic fox is classified as Least Concern (LC) on the IUCN Red List (1).

The Arctic fox (Vulpes lagopus) is superbly adapted for life at sub-zero temperatures (3). While this species is best known for its pristine, white winter coat, during the summer, the coat becomes brown on the upperparts, with light grey or white underparts (3), and is half as thick (4). In addition, to the ‘white’ form of Arctic fox, a ‘blue’ form also occurs, which in some areas is light brown with a bluish sheen in the winter or dark brown to black in other areas, but becoming chocolate brown in the summer (3) (5). The dense, woolly coat of this species has the best insulative properties of all mammals, and helps this species survive at temperatures of -50 degrees Celsius in the wild, and up to -80 degrees Celsius during captive tests (2) (3). Some other adaptations for life in the Arctic include small, heavily furred ears and a short nose to reduce heat loss, as well as fur on the soles of the feet, giving the name in latin “hare foot” (5), and increased blood flow to the feet pads to prevent freezing (2) (3). There is some debate as to the taxonomic status of this species, both in terms of the number of subspecies, and whether it should be classified under the genus Vulpes or Canis (3).

The Arctic fox has a circumpolar distribution throughout the Arctic, extending across Eurasia, North America, the Canadian archipelago, Siberian islands, Greenland, Iceland and Svalbard. This species also extends its range northwards over sea ice, and has been recorded in the vicinity of the North Pole, while its southern range limits extend to subarctic regions, including islands in the Bering Sea and Gulf of Alaska, as well as the southern tip of the Hudson Bay, Canada (1).

The Arctic fox occupies arctic and alpine tundra (1), with the ‘white’ form occurring principally in open, treeless plains, while the ‘blue’ form is more common in coastal and shrubby habitats (4).

Moving easily over ice and snow, and even capable of swimming when necessary, the Arctic fox is known for its far ranging movements, which exceed those of any terrestrial mammal except man. During the seasonal movements that occur in many populations during the autumn and winter, individuals have been recorded travelling over 800 kilometres from shore out over the pack ice (2), with a total of up to 4,500 kilometres over a winter season (5). In order to survive in the harsh Arctic environment, the Arctic fox hunts and scavenges a wide variety of prey according to location, including sea birds and ptarmigan, fish, marine invertebrates, and mammals, such as adult seal carcasses, as well as live ringed seal pups located in chambers beneath the snow (1) (2). The majority of this species’ diet, however, consists of lemmings, and its population can fluctuate greatly in response to annual changes in lemming abundance (1). While the basic social unit for the Arctic fox is the breeding pair, this species usually hunts alone, and may cache food for later use (3). It is also possible that additional adults stay within the den, with several breeding females nursing the offspring together (5). When food is not available, the arctic fox is able to reduce its metabolic rate by half, while remaining active, thereby conserving energy and allowing more time to find food before starvation occurs (2). While starvation is a significant cause of mortality for this species, both adults and young are preyed upon by the wolverine (Gulo gulo), the red fox (Vulpes vulpes) and golden eagle (Aquila chrysaetos) (3).

The Arctic fox breeds between February and May, with births taking place from April to July, following a gestation period of 51 to 54 days (2) (3). Litter size is dependent on food availability, with 5 to 10 young produced on average (1), but as many as 19 young in areas where food is particularly abundant (3). The young are born and nursed inside complex dens, which provide shelter and protection against predators (3). Some den sites are centuries old, used by numerous generations of foxes, and can become very large (2), with up to 150 entrances (3). Both parents contribute to the rearing of the young, with the female providing milk for the first three weeks and rarely leaving the den, while the male brings food. As the cubs begin to take more meat, the female also starts hunting, and in some cases, the pair is assisted by ‘helper’ individuals, which are usually the offspring from the previous year. The young become independent of the den at eight to ten weeks old and reach sexual maturity at ten months (3). During the breeding season Arctic fox pairs are strongly territorial, marking territory boundaries with urine, and employing vocalisations and postures, such as holding the tail erect, during disputes with conspecifics (3).

The Arctic fox has a long history of exploitation for the fur trade, and while hunting pressure has abated in recent years, it remains the most important terrestrial game species in the Arctic (1). Fortunately, this species is capable of maintaining stable populations even when heavily hunted, due to a relatively high reproductive output. Hence the global population of the Arctic fox is currently abundant and is not considered to be threatened (1). This should not, however, obscure the status of some regional populations, such as those in Fennoscandia, the Russian island of Mednyi and the Pribilof Islands, where numbers are declining and may be critically low (1). Regional threats include disease, exposure to toxic pollutants, direct persecution and breeding with escaped, captive-bred ‘blue’ foxes from fur farms, which ‘pollute’ the gene pool of the ‘pure’ wild population (1). In 2009, the International Union for Conservation of Nature and Natural Resources (IUCN) designated the Arctic fox as a flagship species for ongoing climate change by referring to expansion of the boreal forest, red fox (Vulpes vulpes) competition and prey scarcity as potential threats connected to climate change (5).

While the Arctic fox is generally unprotected throughout most of its range, in Sweden, Finland, and Norway, where this species’ population is very low, it has been fully protected for over 60 years. Unfortunately, in other areas where this species is under threat, such as St Paul Island, protection is lacking and persecution is ongoing (3). In Greenland, Svalbard, Canada, Russia and Alaska, trapping for fur is widespread, but controlled by well-enforced laws requiring trapping permits and specifying a limited trapping season (1).

The Arctic fox is also protected to some extent by virtue of its presence within some protected areas, particularly in Sweden and Finland (1). In addition, between 2003 and 2008 a conservation project celled SEFALO+ helped to promote the recovery of the Arctic fox in Sweden, Finland and Norway. It is hoped that the success of the project will lead to continued conservation-focused management of the Arctic fox in these countries, thereby ensuring its survival (6).

Learn more about the conservation of the Arctic fox:

Authenticated (26/01/2011) by Professor Anders Angerbjörn, Department of Zoology, Stockholm University,
http://www.zoologi.su.se/en/about/staff/person.php?suuid=angerbj

  1. IUCN Red List (June, 2009)
    http://www.iucnredlist.org
  2. Nowak, R.M. (1991) Walker's Mammals of the World. The Johns Hopkins University Press, Baltimore and London.
  3. Angerbjörn, A., Hersteinsson, P. and Tannerfeldt, M. (2004) Arctic fox Alopex lagopus (Linnaeus, 1758). In: Sillero-Zubiri, C., Hoffmann, M. and Macdonald, D.W. (Eds) Canids: Foxes, Wolves, Jackals and Dogs - 2004 Status Survey and Conservation Action Plan. IUCN, Gland, Switzerland and Cambridge, UK.
  4. Burnie, D. (2001) Animal. Dorling Kindersley, London.
  5. Angerbjörn, A (January, 2011) Pers. comm.
  6. Angerbjörn, A., Meijer, T., Eide, N.E., Henttonen, H. and Norén, K. (2008) Saving the Endangered Fennoscandian Alopex lagopus: Layman’s report. SEFALO+, Stockholm. Available at:
    http://www.zoologi.su.se/research/alopex/publications/intermimsrapport-short.pdf