Sakis are essentially diurnal and arboreal, descending only occasionally to lower branches or shrubs in their search for food. They seldom descend to the ground or climb to the treetops because their major predators (small cats, large snakes and avian raptors) inhabit these niches. They descend vertical supports tail-first. While usually moving on all fours, they are capable of making long leaps through trees, and have been observed running in an erect posture along horizontal branches. When moving bipedally they hold up their arms with fingers extended for balance. When alarmed they can move quite rapidly. When eating mammals and birds, they tear apart their prey with their hands. They have been observed going into tree hollows to collect bats, which are torn apart and skinned before being consumed. Pale-headed sakis sleep curled on a branch like a cat, and sometimes hang by their hind feet when feeding. They travel either in family groups or alone. While usually quiet in captivity, they emit loud, penetrating calls in the wild.