The mating (or "rutting") season of the muskoxen begins in late June or early July. During this time, dominant bulls will fight others out of the herds and establish harems of usually six or seven cows and their offspring. Fighting bulls will first rub their preorbital glands against their legs while bellowing loudly, and then display their horns. The bulls then back up 20 meters, lower their heads, and charge into each other, and will keep doing so until one bull gives up. Subordinate and elderly bulls will leave the herds to form bachelor groups or become solitary. However, when danger is present, the outside bulls can return to the herd for protection. Dominant bulls will prevent cows from leaving their harems. During mating, a bull will casually kick an estrous cow with his foreleg to calm her down and make her more receptive to his advances. The herds reassemble when summer ends.