Classification and Range
The class of foxes belongs to the order Carnivora and in the family Canidae. There are 20 species of foxes in six genera: Alopex (arctic foxes), Cerdocyon (crab-eating foxes), Otocyon (bat-eared foxes), Pseudalopex (South American foxes), Urocyon (gray foxes) and Vulpes (all other foxes).* Debate continues on whether the arctic fox should be classified into Vulpes or into its own genus of Alopex. The arctic fox is also known as the polar fox or the white fox.
Linneaus, the 18th century botanist, bestowed the scientific name lagopus (rabbit or hare-footed) on the arctic fox for its distinctive furred paws. As its name implies, the arctic fox’s range includes the circumpolar northern Arctic regions of North America, Scandinavia, Siberia, Greenland and Iceland.
Arctic foxes inhabit treeless arctic and alpine tundra. They live in both coastal and inland areas of the mainland and on islands. Arctic foxes travel extensively and possess large range sizes from 2,100–15,000 acres (850–6,070 ha). Other than humans, the arctic fox travels more extensively than any terrestrial animal.
Arctic foxes are medium-size foxes that weigh from 6–10 pounds (2.7–4.5 kg) and average 43 inches (109 cm) in length from head to tail. The tail length averages 15 inches (38 cm). Females (vixens) are slightly smaller than males. Compared to the slender bodies and long legs of other foxes, arctic foxes have a stocky body with short legs and torso. Arctic foxes also have a short muzzle and short, rounded ears. The arctic fox has dense fur with an especially thick and fine undercoat that comprises 70% of its coat. Arctic foxes have extremely long and bushy tails that muffle the sounds made by their bodies crossing terrain.
Arctic foxes shed their coat twice a year. In springtime, they lose their long winter coats, and in autumn they start acquiring a new winter pelt. A camouflaging change in coloration accompanies these molts. Arctic foxes come in two distinct color “morphs” (also called “forms” or “phases”): the white or polar and the blue morphs. The familiar pure white winter pelt is the white morph commonly associated with arctic foxes. After the spring molt, the white morph has a short summer pelt that appears gray to brown on the face, legs and upper body, while the under body fur is lighter colored. In contrast, the blue morph spends summer with a dark brown, black, light gray or steel blue coat that lightens during the winter. However, the blue morph never turns truly white in color. In the far north, 99% of all arctic foxes are white morphs, while blue morphs make up 90% of those species living on the Aleutian and Pribilof islands. Even though the white morph is genetically recessive, the amount of snow cover in the northern regions probably accounts for its predominance there.
In the wild: Average for those reaching adulthood is 3 years, although a few live as long as 10 years
At the zoo: 6-10 years
In the wild:
Arctic foxes are opportunistic and omnivorous feeders. Small mammals make up their preferred summer diet. However, they also eat plants, bird eggs, insects and fish. Winter diets include small marine mammals, birds, small seals, invertebrates and carrion.
At the zoo:
Thawed frozen quail and mice, along with eggs, fruits and vegetables.
Reproduction and Life Cycle
Arctic foxes sexually mature at 9–10 months of age and usually form lifetime monogamous bonds. A typical family unit consists of a single adult male, an adult breeding female, one or more other adult females and the current year’s offspring. The non-breeding females may be from the previous year’s litter and serve as helpers for the new litter. When digging den sites, arctic foxes select dry, well-drained sandy soil or rocky areas usually with a southern exposure. Dens have a central chamber and multiple entrances for use in emergencies. Some dens have been in use by generations of foxes over the past few centuries.
Mating occurs in mid-spring, and the young (also called kits, pups, whelps or cubs) emerge in late spring or early summer after an average gestation of 52 days. Litters range from three to 12, with an average of seven. Short, dark, brown fur covers all newborn pups, and a single litter may contain both color morphs. By two months of age, the blue morph pups acquire their dark coloration, while the white morph pups develop the contrasting pattern of darker backs, heads and legs with lighter underbodies. Many pups do not reach adulthood, as there are high mortality rates among the young. The male guards the den and may lead intruders away from the den site. He also brings back food for both the mother and her pups. The pups begin eating meat at 1 month old and the mother weans them around one and half months after birth. By 3 months old, the pups begin to travel away from the den and participate in hunts. In autumn, the family unit gradually dissolves and these foxes spend the winters in solitary hunts for food.
Life in the Arctic - Brrrrr
Life in the Arctic is difficult, and the arctic fox is wonderfully adapted to live in very cold climates. While many mammals hibernate during the winter, the arctic fox does not. Its physical characteristics of superb insulation with fur and fat, combined with its stocky body shape enable the arctic fox to conserve body heat. Therefore, it can continue to remain active throughout the frigid months. During winters, their densely furred paws prevent heat loss through their feet. They also have the ability to restrict blood flow to the legs, which helps maintain core body heat. Lastly, the arctic fox has a tremendous tolerance for cold. Its metabolic rate only starts to increase at -58° Fahrenheit (-50° Celsius) and it only starts to shiver when temperatures reach -94° Fahrenheit ( -70° Celsius).
In addition to its physical attributes, the arctic fox has many behaviors that enable it to survive in the far north. They will eat virtually anything edible. Besides their preferred summer diet of lemmings and voles, coastal arctic foxes dine on nesting birds and their eggs. They also eat berries and seaweed. These foxes eat continually and thereby gain insulating fat during summer’s plenty. For later consumption, they stash eggs and other surplus food in their dens or under rocks. When snow arrives, their sharp sense of hearing enables them to locate lemmings in burrows deep under the snow. Their excellent sense of smell helps detect white ptarmigans (a species of bird) against a background of snow and also leads them to carrion left behind by other predators. At times, arctic foxes remain near hoofstock (such as musk ox or caribou) waiting for one to die. They may even trail a polar bear in hopes of leftovers. They have been observed scavenging the remains of seals out on sea ice. When all else fails, they may consume feces of both humans and animals.
- Arctic foxes are noted for high fertility rates. Their litters may produce up to 25 pups, and arctic foxes have the largest litter sizes of all carnivores!
- These carnivores are found farther north than any other land mammal and have been observed less than 38 miles (61 km) from the North Pole!
- The four-year population cycles of lemmings affect arctic fox populations in a repeating cycle. Abundant years for lemmings result in large fox litters. In turn, large fox litters result in smaller lemming populations. This leads to smaller fox litters in the next year!
- Arctic foxes often hide their food in rocky areas later covered with deep snow. To find their cache sites, they spray them with a powerful, skunk-like odor!
- Arctic foxes also affect the populations of some migrating birds!
The arctic fox lives in the zoo’s award-winning Northern Trail. The zoo also has another species of fox, which is the fennec fox in the Adaptations exhibit. Other animals that can be seen at the Northern Trail are bald eagle, gray wolf, magpie, mountain goat, porcupine, river otter, Roosevelt elk and snowy owl.
Arctic foxes are not listed as an endangered species, and although arctic fox populations are abundant, at least three other species of foxes are listed as endangered.** However, arctic fox numbers have declined significantly in some of their native ranges. For centuries, indigenous peoples in Arctic regions sought the warm pelts of arctic foxes for their own use and for the fur trade more recently. In the past two centuries, fur trade considerably reduced numbers of arctic foxes in most of Scandinavia. The world fur trade in arctic fox pelts reached peaks in Siberia, Russia, with over 100,000 pelts taken in a single year. Currently in Alaska, this is reduced to around 4,000 pelts annually. The most prized and expensive pelts come from the rare black or steel blue color morphs. While the fur trade has declined, trapping still continues, and humans also farm captive foxes for their fur.
Other human activities affect arctic fox populations. In Iceland, farmers considered arctic foxes as pests that threatened their sheep and ducks. Thus, they have waged eradication campaigns since the 13th century. On Mednyi Island in the Commander Islands of Russia, domestic dogs introduced mange, which has drastically reduced arctic fox numbers. These foxes are also susceptible to rabies in some areas. Arctic foxes may acclimate themselves close to human settlements, creating further potential conflicts.
Arctic foxes face dangers from other sources; these animals (and especially their young) are prey to other predators. As the red fox’s range expands into that of the arctic fox, these two species compete for food. The larger red fox also preys on the smaller arctic fox. Polar bears and wolves also threaten the arctic fox in two ways. When larger predators decline in numbers, they leave behind less carrion for the scavenging arctic fox. Bears and wolves also prey upon the arctic fox as a source of food. Despite all these hazards, arctic foxes are remarkably successful in most areas of their range.
Sources and Suggested Reading
Macdonald, David. 1999. “Foxes.” The Encyclopedia of Mammals. Barnes & Noble Books, New York. pp. 68–75.
Middlebrook, C. 1999. “Alopex lagopus” (On-line), Animal Diversity Web. Accessed June 23, 2004 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Alopex_lagopus.html
Stephenson, Bob. "Alaska Arctic Fox" (On-line), Alaska Department of Fish and Game. Accessed June 23, 2004 at http://www.ak.blm.gov/animals/arcfox1.html
Tannerfeldt, Magnus. “The Arctic Fox Alopex lagopus” (On-line), Accessed June 23, 2004 at http://www.zoologi.su.se/research/alopex/the_arctic_fox.htm
Ling, Mary. 1991. Amazing Wolves Dogs and Foxes. Alfred A Knopf, NY, New York.
Matthews, Downs. 1995. Arctic Foxes. Simon & Schuster Books for Young Readers, NY, New York.
Lioncrusher’s Den: http://www.lioncrusher.com/animal.asp?animal=3
IUCN/SSC Canid Specialist Group: Arctic Fox: http://www.canids.org/SPPACCTS/arcticfx.htm
2003 IUCN Red List off Threatened Species: http://www.redlist.org/search/details.php?species=899
Natural Worlds: http://www.naturalworlds.org/wolf/canids/Alopex_lagopus.htm
* Taxonomic classification varies between references. Classification information used in this fact sheet was taken from Mammal Species of the World: A Taxonomic And Geographic Reference, edited by Don E. Wilson and Dee Ann M. Reeder, Second Edition, 1993.
**There are several international and federal agencies that determine the endangered status of species. WPZ designates a species as endangered if it is listed as endangered on the IUCN (International Union for the Conservation of Nature) Red List, the US Fish & Wildlife Service's Endangered Species List, or on Appendix I of CITES (Convention on the International Trade of Endangered Species of Flora and Fauna).