The muskox is well adapted to the cold, and is one of the few large mammals capable of living year-round in the severe Arctic environment. The thick coat provides excellent insulation, and the short, stocky legs and large, rounded hooves help the muskox to move through snow (4), although it is not that well adapted to digging through heavy snow for food and so is generally restricted to areas with shallower snow (1) (3) (7). The diet consists mainly of grasses and sedges, as well as browse such as willow and crowberry, and some forbs. Predators include wolves and bears, and the muskox has a characteristic defence behaviour, in which the herd bunch together, often forming an impenetrable line or circle, with the calves inside and the adults’ sharp horns facing outwards (2) (4) (5) (6) (7).
A social species, the muskox typically forms mixed herds of around 10 to 20 animals, or sometimes as many as 100, although males can also be found alone or in separate bachelor herds. During the summer, smaller harem groups form, led by a dominant bull, with rival bulls excluded using threats, displays, or serious fights. Dominance battles are impressive contests, in which two rival males meet head-on after a high speed charge, often accompanied by roaring, and clash the horns together in an impact that can be heard a mile away (2) (5) (6) (7)
. Mating occurs between July and September, and a single calf is born between April and June, after a gestation
period of around eight to nine months (2) (4) (5) (6) (7)
. Highly precocial
, the calf is able to follow the female and join the herd within hours of birth, but may not be fully weaned for more than a year. Females reach sexual maturity at around 3 years and males at around 5 to 6 years, and individuals may live for up to 20 to 24 years (2) (4) (5)
. The muskox has a relatively low reproductive rate, the female giving birth only once every one to three years (2) (4)