A male howler monkey uses a howl to announce his group’s presence.
Howler monkeys produce some of the loudest calls made by land mammals. Their deep howls can carry for several kilometres through tropical forest, helping groups space themselves apart and avoid unnecessary confrontations. The calls are often made around dawn, although howling can occur at other times as well.
The sound is amplified by an enlarged hyoid bone in the throat, which acts as a resonating chamber. Males generally have a larger hyoid apparatus than females, contributing to their especially powerful voices. A group may join in a chorus, with several individuals contributing to the display.
Howling is therefore more than a simple warning. It can communicate a troop’s location, advertise group occupancy, and help regulate access to feeding areas. The word “howl” is the standard name for this famous vocalization.