Once found throughout the Arctic, musk oxen were wiped out from northern Alaska after firearms appeared in the region during the mid-1800s.

Reintroduced into the area 25 years ago, musk oxen in the refuge currently number a few hundred animals.

Musk oxen are uniquely adapted to their frigid environment, where temperatures regularly drop to minus 30 or colder. Their thick wool provides insulation, and their large, squat bodies retain heat. In summer, musk oxen feed on a wide variety of plants along the coastal plain's major rivers; in winter they move to areas with low snow cover, where they feed on sedges and shrubs. As year-long denizens of the coastal plain, they also provide a crucial source of food for predators and other animals even at times when other food sources are scarce. When threatened, musk oxen form a circle around their young; wolves dart in and nip at the adults until the oxen begin to run and the wolves can gain access to the calves.

The preferred habitat of musk oxen largely coincides with the area the oil industry wants access to, and oil development in the refuge would displace them from favorite winter haunts. In the bitter cold of an Arctic winter, energy wasted in roaming farther for food and shelter and to avoid disturbances could decrease reproduction and threaten the species.