Howler Monkeys and Spider Monkeys: Atelidae

All atelids are arboreal (tree-dwelling) but occasionally descend to the ground. They are diurnal (active during the day). Some species have grooming sessions and play time. Atelids do not defend territories. They generally move through the forest on all fours with brachiation (brake-ee-AY-shun; swinging below branches using the arms), usually assisted by the tail.

Adults have several mating partners. Females have single births, which occur at different intervals depending on species. The mother alone tends to the infant. Except for howler monkeys, young males remain with the group, while females leave to join other males. Male howler monkeys form their own group and invade another group, killing the young.