The dominant male's response to an aerial predator is to hide and not give an alarm bark until other males form a coalition to threaten the predator. The alpha male is very aggressive to other groups whenever 2 groups meet. Adult males associate together and cooperatively defend their group, whereas each female forages separately, avoiding other adults. Feeding ecology influences male mating strategy, aggression, and cooperation. Little male-male aggression is seen during estrus.
Loud vocalizations advertise a troop's location, and other groups avoid the area.
Brazil, Colombia and Venezuela. The shoulders are lighter than the overall body color, which varies from light to dark brown. The facial pattern varies with the subspecies, except for the black sideburns. The hands and feet are always black. The prehensile tail is darkest at the tip.