Body temperature, which is normally 98.6 F, is maintained through a thick layer of fur, a tough hide, and an insulating layer of blubber. Polar bears are completely furred except for the nose and footpads, which are black. A polar bear's skin is black. Its coat is about 1.2 inches thick. A dense, woolly, insulating layer of underhair is covered by a relatively thin layer of stiff, shiny, clear guard hairs. The fur is oily and water repellent and can be white, creamy yellow or brown.
Polar bears' paws are huge compared to body size, reaching 12 inches in diameter. We're talking built-in snowshoes here. Each toe has a thick, curved, nonretractable claw that can be used for grasping prey and for traction when running or climbing on ice.
Polar bears are capable of traveling 19 miles or more per day for several days. The average walking speed is 3.4 mph, but when being chased or charging prey, their maximum speed is 25 mph for short distances. They are also strong swimmers, and can swim for several hours at a time over long distances; some have been tracked swimming continuously for 62 miles. Swimming speed can reach 6.2 miles per hour. Polar bears usually swim under water at depths of only about 10 to 15 feet. They can remain submerged for as long as two minutes.
On warm days polar bears sprawl out on the ground or ice, sometimes on their backs with their feet in the air. They may also make temporary snow or earthen pits to lie in. On cold days they curl up and often cover their muzzle area. During the winter, some polar bears excavate temporary dens or find natural shelters to stay warm. They may use these shelters for several months at a time. Polar bears are basically solitary. Usually, only two social units exist: adult females with cubs and breeding pairs, and the breeding pairs only remain together for about a week, mating several times.
Female polar bears reach sexual maturity at about four years; males at about six years. Most male polar bears don't successfully mate until eight to 10 years and older. There are about three adult males to every breeding female. Before mating, a female polar bear may be accompanied by several males. The males fight fiercely among themselves until the strongest or largest male succeeds in chasing the others away. Fights are rarely fatal, but do result in broken canines and scars on the head, neck, and shoulders.
Grizzly bears are omnivorous. In spring they graze first on roots and then switch to new grasses and sedges as they emerge. Bears in mountainous areas move up and down slopes in response to available vegetation. On the barrens they move to areas of early snow melt in the spring to feed on new growth. During late summer and fall they feed primarily on berries. They also eat a great many lemmings and ground squirrels, which they excavate from burrows. With respect to large animals, bears are opportunistic predators and will kill caribou, moose, muskoxen and sheep if the occasion arises.
Muskoxen are more closely related to sheep and goats than to oxen. Muskoxen stand 4 to 5 ft high at the shoulder, with females measuring 4.4 to 6.6 ft in length. The small tail, often concealed under a layer of fur, measures only 3.9 inches long. Adults, on average, weigh 600 lb and range from 400 to 900 lb. Their life expectancy is 12–20 years. The thick coat and large head often suggests a larger animal than the muskox truly is and, the bison, to which the muskox is regularly compared, can weigh up to twice as much. Their coat, a mix of black, gray, and brown, includes long guard hairs that almost reach the ground. Muskoxen are occasionally domesticated for wool, meat and milk. The wool, qiviut, is highly prized for its softness, length, and insulation value.
Muskoxen are native to the Arctic areas of Canada, Greenland, and the United States. The world population is estimated at between 80,000 and 125,000, with an estimated 68,788 living on Banks Island.
Muskoxen will eat grasses, arctic willows, woody plants, lichens and mosses. When food is abundant, they prefer succulent and nutritious grasses in an area. Willows are the most commonly eaten plants in the winter. Muskoxen have a high threshold of fat reserves before conceiving which reflects their conservative breeding strategies. Winter ranges typically have shallow snow to reduce the energetic costs of digging through snow to reach forage. The primarily predators of muskoxen are Arctic wolves, which may account for up to half of all mortality for the species. Other predators, likely primarily of calves or infirm adults, can include grizzly bears and polar bears. Credit for this text and more informationcan be found on Wikipedia.
Tundra wolves are associated with migratory caribou and have a less developed territory than wolves that depend on non-migratory prey. This is because caribou migrate over long distances and there would be no advantage to protecting an area that may not have any caribou during part of the year. In central Nunavut, the wolf winter range may be defined by the distribution of caribou. In early spring, when caribou group together to begin their northward migration, the wolf density in those areas' may be as high as one wolf per 10km squared.
The arctic fox is the only canid which changes the colour of its coat in the summer. The back, tail, legs and head are brown, and the sides and belly are blond. This two-tone brown pelage lasts only for July and August and enables the fox to blend into the summer tundra. This coat is much shorter than the winter coat.
Arctic foxes live primarily on lemmings and voles. In winter, the lemmings must first be located in their tunnels under the snow. Most hunting is done in darkness, so the fox relies heavily on its acute sense of smell and hearing to detect its prey. Winter in the Far North is harsh and limited food resources can have a profound effect on arctic fox numbers. Brown and collared lemmings undergo population peaks every three to five years followed by crashes caused by overcrowding and other factors, such as insufficient snow insulation in winter. In addition to lemmings, the winter food of arctic foxes consists of arctic hares, ptannigan and carrion. They will trail wolves to obtain scraps from abandoned carcasses, and follow polar bears across frozen seas to scavenge from leftover seals. They may also kill ringed seal pups in their birth dens. In areas of human development, arctic foxes may scrounge food handouts or garbage.
In late winter, arctic foxes seek dens in which to raise their young. The dens are usually dug in gently sloping, sandy soil near rivers or lakes or on elevated areas free of permafrost. They have complex underground tunnels with numerous entrances and several metres of interconnecting tunnels. Good den sites are not common so they are occupied in successive years, becoming more complex with use. Wolves may move into old fox dens to raise their own young, and grizzly bears can cause extensive damage by digging in search of arctic ground squirrels.
Arctic foxes are sexually mature by 10 months of age. They breed in March or April. If the preceding winter was severe and the foxes are malnourished, they may breed later than usual or not at all. One litter is produced each season after a gestation period of about 51 days. On average, six pups are born between mid-May and mid-June. Litter sizes vary widely, but are generally between 3 and 9 pups, fluctuating with food availability and geographic location. Foxes inhabiting coastal areas have smaller litters than foxes which occupy inland tundra.
The colour of a caribou's coat varies seasonally. The adult males are the first to begin moulting in late June. Cows that are nursing have the greatest nutritional needs and complete their moult last. The old fur that has faded to very light beige over the long winter falls out in large patches revealing a new chocolate brown coat. When the moult is complete, caribou are uniformly dark brown with a white belly and white mane. Adult males also sport a white flank stripe and white socks above their hooves. In the fall, as white-tipped guard hairs grow out through the summer hair for extra winter insulation, caribou become a more uniform light brown. The exceptional warmth of the winter coat is the result of individual hairs which are hollow. The air cells in the hair act as an insulating layer to con-serve body heat.
Barren-ground caribou have the largest antlers in relation to their body size of any deer species and are the only species in which females grow antlers. Antlers are shed and regrown each year.
Caribou have several gaits. When migrating, they walk at about 7 km/hr, covering between 20 and 65 km a day. When startled, a caribou runs in a loose, even trot. The head is held high with the nose up and the tail erect. When galloping at top speed most caribou can outrun wolves, their major predator, but wolves close in quickly on any animal that stumbles or takes a wrong turn. Caribou are excellent swimmers. Their hollow hairs enable them to float high in the water and their broad hooves propel them along at speeds of about 3 km/hr.
Arctic hares look like rabbits but have longer ears and can stand up taller, they can live/maintain themselves in cold places unlike rabbits. They can travel together with many other hares, sometimes huddling with dozens or more, but are usually found alone, taking in some cases more than one partner. The arctic hare can run up to 40 miles per hour. Its top predator is the arctic wolf.