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The Arctic Fox (Alopex lagopus), also known as the White Fox, is a fox of the order Carnivora. It is a small fox native to cold Arctic regions of the Northern Hemisphere. It is common in all three tundra biomes. Although some authorities have suggested placing it in the genus Vulpes, it has long been considered the sole member of the genus Alopex.
The Arctic fox has evolved to live in the most frigid extremes on the planet. Among its adaptations for cold survival are its deep, thick fur, a system of countercurrent heat exchange in the circulation of paws to retain core temperature, and a good supply of body fat. The fox has a low surface-area-to-volume ratio, as evidenced by its generally rounded body shape, short muzzle and legs, and short, thick ears. Since less of its surface area is exposed to the cold, less heat escapes the body. Its furry paws allow it to walk on ice floors in search of food. It is also able to walk on top of snow and listen for the movements of prey underneath. Its thick fur is the warmest of any mammal.
Arctic foxes tend to be active in early September to early May. The gestation period is 52 days. Litters tend to average 6-7 pups but may be as many as 11. Both the mother and the father help to raise their young. The female leave the family and form their own groups and the males stay with the family.
Foxes tend to form monogamous pairs in the breeding season. Litters of between 4 and 11 kits are born in the early summer. The parents raise the young in a large den. Dens can be complex underground networks, housing many generations of foxes. Young from a previous year's litter may stay with the parents to help rear younger siblings.The cubs are brownish and as they get older they are white.
The Arctic fox will generally eat any meat it can find, including lemmings, Arctic Hare, reptiles and amphibians, eggs, and carrion. Lemmings are the most common prey. A family of foxes can eat dozens of lemmings each day. During April and May the Arctic fox also preys on ringed seal kits when the young animals are confined to a snow den and are relatively helpless. Fish beneath the ice are also part of their diet. When its normal prey is scarce, the Arctic fox scavenges the leftovers of larger predators, such as polar bears, even though the bears' prey includes the Arctic fox itself.
The length of the head and body is 55 cm (21.7 in) in the male and 53 cm (21 in) in the female. The tail is 31 cm (12.2 in) long in the male and 30 cm (11.8 in) long in the female. It is 25-30 cm (9.9-11.8 in) high at the shoulder, and males weigh 3.8 kg (8.2 lb) while females can weigh 6 to 12 pounds.
Population and Distribution
The Arctic fox has a circumpolar range, meaning that it is found throughout the entire Arctic, including the outer edges of Greenland, Russia, Canada, Alaska, and Svalbard, as well a cvs in sub-Arctic and alpine areas, such as Iceland and mainland alpine Scandinavia. The conservation status of the species is good, except for the Scandinavian mainland population. It is acutely endangered there, despite decades of legal protection from hunting and persecution. The total population estimate in all of Norway, Sweden and Finland is a mere 120 adult individuals.
The arctic fox is the only native land mammal to Iceland. It came to the isolated North Atlantic island at the end of the last ice age, walking over the frozen sea.
The abundance of the Arctic fox species tends to fluctuate in a cycle along with the population of lemmings. Because the fox reproduces very quickly and often dies young, population levels are not seriously impacted by trapping. The Arctic fox has, nonetheless, been eradicated from many areas where humans are settled.
The Arctic fox is losing ground to the larger red fox. Historically, the gray wolf has kept red fox numbers down, but as the wolf has been hunted to near extinction in much of its former range, the red fox population has grown larger, and it has taken over the niche of top predator. In areas of northern Europe there are programs in place that allow hunting of the red fox in the Arctic fox's previous range.
As with many other game species, the best sources of historical and large scale population data are hunting bag records and questionnaires. There are several potential sources of error in such data collections. In addition, numbers vary widely between years due to the large population fluctuations. However, the total population of Arctic foxes must be in the order of several hundred thousand animals.
The world population is thus not endangered, but two Arctic fox subpopulations are. One is the subspecies Alopex lagopus semenovi on Mednyi Island (Commander Islands, Russia), which was reduced by some 85-90%, to around 90 animals, as a result of mange caused by an ear tick introduced by dogs in the 1970’s. The population is currently under treatment with antiparasitic drugs, but the result is still uncertain.
The other threatened population is the one in Fennoscandia (Norway, Sweden, Finland and Kola Peninsula). This population decreased drastically around the turn of the century as a result of extreme fur prices which caused severe hunting also during population lows. The population has remained at a low density for more than 90 years, with additional reductions during the last decade. The total population estimate for 1997 is around 60 adults in Sweden, 11 adults in Finland and 50 in Norway. From Kola, there are indications of a similar situation, suggesting a population of around 20 adults. The Fennoscandian population thus numbers a total of 140 breeding adults. Even after local lemming peaks, the Arctic fox population tends to collapse back to levels dangerously close to non-viability.
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