Males without females form bachelor groups of 2-32. Females generally remain in their natal group but sometimes, younger males may form their own group by breaking off with some females. Older males may live by themselves. All members of a group join in a booming whoop in the morning, helping to space the groups apart in the dense canopy. They also whoop when they're happy.
Males compete aggressively to be the only dominant male in the group.
Thus males in such groups rarely hold on to their position for more than 2 years. Sometimes, bachelor groups can attack the male in the single-male group, together driving him out. The highest-ranking male in the bachelor group then becomes the dominant and chases out the others. With a change in leadership, all male young which are weaned are chased out and infants of both genders may be killed. Normally, females bear young once every 1-2 years.