US Fish and Wildlife Service
Muskox are large cloven-hoofed mammals that have a long shaggy overcoat (their hairs can be up to 2 feet long!). They live in the far north of Canada, where winters are long and cold. Muskox are vegetarians: they eat grasses and other plants that are abundant on the tundra in the summer. In the winter, when they have to dig through the snow to find food, they eat woody shrubs, especially the tallest plants that are easiest to dig out of the snow. Muskox tend to live for around 20 years in the wild.
Like most herbivores or grazers, muskox have developed some special adaptations to help them escape predators such as wolves, polar bears, grizzly bears, and humans. Muskox have very good sight and hearing to detect an approaching predator, and despite their size and appearance they can run very fast if they need to. They also have large horns that they can use to jab at or pick up and toss an attacking wolf or other predator. Muskox live together in herds, and if a predator is approaching a herd and there are young or baby muskoxen around, the adults will form a protective circle around the young, facing outward to prevent attack from any direction. Many scientists think this is fascinating and have spent lots of time, energy, and money studying this phenomenon.
Muskox cooperate within their herds: they sometimes sleep next to each other to share warmth, and when the snow is very deep they take turns breaking a trail to make travel easier for the entire herd.
Map of the range of muskox in North America. Red areas are where muskox populations have not been disturbed or eradicated. Blue areas are where muskox have been reintroduced. By Masae (Own work)
Forsyth, Adrian. Mammals of North America: Temperate and Arctic Regions. Firefly Books: Buffalo, New York, 1999.