Arctic fox found in two different colours
There are two colour variants of the Arctic fox, blue and white. The winter coat of a blue fox varies from light blue-grey to dark brown, while the summer coat is chocolate-brown. The white coloured fox is only truly white in winter, and in summer its back and legs are dark brown and its belly and flanks yellowish-white in colour. The blue form is most often found along the coast and on smaller islands.
Endangered on the mainland, stable population in Svalbard
Even though the Arctic fox has been totally protected in Norway since 1930, the situation for the mainland population is now critical. The species is classed as endangered in Norway's Red List. Arctic foxes are totally protected on Jan Mayen and Bjørnøya, but may still be trapped in the rest of Svalbard, except in protected areas. The population density in Svalbard is relatively high when compared to the alpine regions of Scandinavia. The Arctic fox was eradicated on Jan Mayen in the 1930s as a result of trapping.
Steady food supplies give a stable population
There are no small rodents in Svalbard, except in a limited area west of Longyearbyen. Food supplies for Arctic foxes appear to be more stable in the archipelago than in other areas where they are more dependent on small rodents. The population is therefore relatively stable.
Arctic foxes will eat whatever is available, from carrion and refuse to prey they catch themselves. Food is far more available in the summer, when foxes eat mainly seabirds, geese and eggs, reindeer carcasses and ptarmigan. In winter, food is in much shorter supply, and the foxes survive on seal and reindeer carcasses, ptarmigan, food they have caught and refuse from the settlements.
Arctic foxes are monogamous
Arctic foxes are monogamous, and each pair establishes a territory, or home range, which they use for several years. In Svalbard, the size of a territory has been calculated to 35-50 km2. Foxes denning by the coast tend to have smaller territories than those denning in the valleys. However, most Arctic foxes in Svalbard are non-breeding animals. These are regularly observed on the drift ice several hundred kilometres from land, which suggests that they roam over large areas, probably between Greenland and western Siberia.
Well-adapted to Arctic conditions
Arctic foxes have a lower metabolic rate and lower body temperature in winter, which allows them to conserve energy. They also show a number of other adaptations that allow them to survive the harsh Arctic winter. The winter coat provides superb insulation, and they develop a thick layer of fat as a food reserve. The short snout and small rounded ears also help to conserve heat.
In addition, Arctic foxes can lower their metabolic rate even further when food is in short supply, so that they use their energy reserves more slowly. This means that they can survive starvation for longer, and are more likely to have a chance of finding food again.
Arctic foxes can harbour disease
Arctic foxes can spread diseases such as rabies and parasites to both people and other animals. The species is the main carrier of the rabies virus in the Arctic, and also the main host of a dangerous parasite, the tapeworm Echinococcus multilocularis .
It is difficult to say how long rabies has been present in Svalbard, but the first documented outbreak in Arctic foxes was registered in spring 1980, when 12 animals were diagnosed with rabies. In the period 1981-1992, the virus was found in a total of six Arctic foxes.
Trichinella sp., the nematode parasite that causes trichinosis when it penetrates the muscles of the host animal, was first found in foxes in Svalbard in 1983. The parasite does not appear to cause symptoms of trichinosis in Arctic foxes in Svalbard.
The tapeworm Echinococcus multilocularis was first found in the eastern short-tailed vole in Svalbard in 1999. The Arctic fox is the main host for this parasite, and the vole is the intermediate host. Dogs can also function as the main host, and if people are infected, they can replace the vole in the parasite's life cycle, but this can cause serious disease. The parasite has been found in dog droppings in Longyearbyen and in fox droppings in areas where the voles occur.
Trapping of foxes permitted
The Arctic fox has been an important quarry for trappers and hunters in Svalbard for many years. Although the species is no longer of much economic importance, recreational hunting is still a popular activity among permanent residents. In addition, foxes provide a valuable economic supplement for the few people who still live by hunting and trapping.
According to the regulations relating to hunting and fishing in Svalbard, Arctic foxes may be taken outside the protected areas from 1 November to 15 March. Since 1997, anyone who traps foxes has been required to purchase a hunting licence from the Governor's office, and their catches are registered. The carcasses are collected for scientific studies by the Governor's office and the Norwegian Polar Institute.
We need to learn more about Arctic foxes
To manage Arctic foxes properly, we need to know more about the size of the population, the distribution of the species and migration. In addition, more research is needed into the effects of trapping, concentrations and effects of organic pollutants in foxes and the vulnerability of the species to various forms of environmental disturbance.
We also need to learn more about its biology - its ecology, adaptations to its habitat and energy needs. The Norwegian Polar Institute is running projects in a number of these fields. More information is also needed on diseases and parasites, especially rabies and the tapeworm Echinococcus multilocularis.