A battle may include 20 clashes. Bull muskoxen have heavily armored skulls to protect them from the shock of impact. Four inches of horn and three inches of bone lie directly over the brain in the area of contact. The group defense formation adopted by muskoxen in response to predators is well known. When danger approaches, muskoxen run together.
Every animal tries to face the source of the threat.
If only one predator is nearby, the defense formation takes the form of a line. If several predators surround the group, as with a wolf pack, the formation becomes a compact circle with all muskoxen facing outward. Occasionally, one or more animals will charge the predator. The muskox s defense strategy is extremely effective against its principal enemy, the wolf. Unless the herd stampedes, it is nearly invulnerable to wolf attack.