Although muskoxen look like large hairy cattle or bison, they are in fact relatives of goats and sheep. These animals live on the windswept tundra within the Arctic Circle. This habitat forms in places that are too cold and dry for trees to grow. There is only enough water to sustain grasses and other hardy plants.
The musk ox undertakes what is known as reverse migration, heading not to more sheltered lowland areas at the approach of the bitter Arctic winter, but out to the bleak, exposed uplands, where winds blow snow away. This allows them to find grazing.
The musk ox's body is covered in long fur, except the area between lips and nostrils. The fur not only keeps the animal warm, but also protects it against the vast numbers of biting insects that swarm across the tundra during the short summer.
Both sexes of this species have large, hooked horns. Male musk ox are larger than females, because they must fight other males to win and defend a harem of females. They butt each other with their horns in contests of strength. During the mating season, the bulls produce a strong, musky odour. Muskoxen live in herds, usually of 15-20 animals but occasionally up to 100 strong. Their presence here often attracts wolves, hoping to overpower a young calf. When predators threaten, the herd crowds together, often in a circle or semi-circle, with the calves in the middle. This formation provides a highly effective defence, since adversaries are faced with a wall of horns and risk being gored if they attack.
Distribution: Occurs in parts of western and northern Alaska, through northern Canada west of Hudson Bay, up to Greenland, where it is more widespread in western areas.
Weight: 180 - 380 kg (396 - 836 lb).
Length: 210 - 259 cm (83 - 102 in), including tail.
Maturity: Females 3-4 years; males 5 - 6 years.
Gestation Period: About 255 days.
Breeding: Generally 1, occasionally twins; weaning occurs at 10 - 18 months.
Food: Grazes on grass and sedges, and browses on shrubs.
Lifespan: Typically 20-24 years.
Status: Common, although extinct in Alaska.
The horns are low-set on the central area over the top of the head, called the boss.
Individual hairs may measure up to 61 cm (24 in), virtually trailing down to the ground.
The legs are free of longer hair, helping the musk ox to move through snow more easily.
An adult charges out from the circle with its head down, directly at the wolves, while others maintain the defensive shield around the young.