A monkey of forests in Mexico, Belize and Guatemala. It feeds mainly on leaves in the trees, and groups use calls to signal their territories.
Near the tail tip is a hairless, thick-skinned area that helps it grip branches. Males have an enlarged hyoid bone and a larger throat pouch than females.
Some black howler monkey groups place a hand in front of the mouth while roaring. Researchers saw the behaviour in six of eight groups at Palenque National Park in Mexico and one of seven groups in nearby fragmented forest. It was absent from captive groups on the distant Yucatan Peninsula.
Only adult and subadult males in the seven groups performed the movement, always with a roar. Hand position changed the sound’s acoustic structure, and the behaviour became more frequent when a neighbouring group was visible. Group members and neighbouring males also responded with more calls.
An extinction-risk assessment has not been added yet.
A study of 34 forest fragments around Palenque National Park recorded 393 black howler monkeys and found that forest cover in the area fell by 23.3% from 2000 to 2017. Fragment area and connectivity were associated with population size and composition. The authors said both forest area and links among fragments should be maintained and increased. The study identifies local landscape priorities for conservation.