Howler Monkey (Alouatta palliata)

MammalPrimateAmericas

Overview

Howler monkeys (genus Alouatta) are large New World monkeys of Central and South American forests, and they are among the loudest land animals on Earth. The mantled howler (Alouatta palliata), shown here, is a typical species — a stocky, mostly black monkey with a long, strongly prehensile tail that acts as a fifth limb. Their fame comes from their voices: at dawn and dusk, males produce deep, resonant roars that can carry for several kilometres through the forest.

That astonishing call is made possible by a specially enlarged throat bone (the hyoid), which works like a resonating chamber.

Note: there are several howler species; details here use the mantled howler as a reference. Treat general statements as approximate and verify against authoritative sources.

Habitat & Range

Howler monkeys range from southern Mexico through Central America and across much of tropical South America, in rainforest, dry forest, mangroves, and gallery forest. They are highly arboreal, spending almost all their time in the trees, and different species occupy a wide variety of forest types across this large range.

Diet

Howlers are folivores — among the most leaf-dependent of New World monkeys — supplementing leaves with fruit, flowers, and buds. Leaves are low in energy, so howlers conserve energy by resting a great deal, spending much of the day quietly digesting their fibrous diet. They help disperse seeds of the fruits they do eat.

Behavior

Howler monkeys live in groups and are best known for their dawn chorus: males (and sometimes females) roar to advertise their group's presence and spacing, allowing neighbouring groups to avoid costly direct confrontation. The enlarged hyoid bone amplifies these calls into some of the loudest sounds any land animal makes. Otherwise howlers are relatively slow, deliberate movers, using their prehensile tail to hang and feed, and they spend much of their time resting.

Human Interaction & Conservation

Howler monkeys are iconic voices of the Neotropical forest and a highlight for ecotourists. Many remain reasonably widespread, but they depend on forest cover and are affected by deforestation, fragmentation, hunting, and disease (such as yellow fever outbreaks); some species and populations are of conservation concern. Consult the IUCN Red List for species-specific status.

More photos of the howler monkey