Howler Monkey

Howler Monkey facts at a glance

How big is a howler monkey?

An adult howler monkey measures 90 cm long — about 52% of the height of an average adult person (1.73 m) — and weighs around 8.0 kg, about 11% of an average adult’s body weight (70 kg).

What is a group of howler monkeys called?

Explore more animal collective nouns and baby animal names .

The famous howl

Howler monkeys are named for the deep, roaring calls that make them one of the loudest land animals in the Americas. Males produce these booming howls using an enlarged hyoid bone in the throat that acts as a resonating chamber. The calls carry for several kilometres through dense forest and are used to space out rival troops without the need to fight. Choruses are most striking at dawn and dusk, when neighbouring groups answer one another across the canopy.

Range and habitat

Howler monkeys, of the genus Alouatta, live throughout the tropical forests of Central and South America, from southern Mexico to northern Argentina. They inhabit a range of woodland, including rainforest, dry forest, and mangrove, wherever there are enough tall trees. Almost their entire life is spent in the canopy, where they find food, sleep, and travel. They are among the most widespread of the New World monkeys.

Diet and slow metabolism

Howlers are folivores, feeding mainly on leaves along with fruit, flowers, and buds. Leaves are low in energy and slow to digest, so the monkeys have an enlarged gut where bacteria ferment the tough plant material. To cope with this low-energy diet they rest for much of the day, sometimes for 15 hours or more. When fruit and young leaves are plentiful they take advantage of the richer food.

Movement through the canopy

Howler monkeys move slowly and deliberately through the trees, rarely leaping and instead climbing carefully from branch to branch. Their strong, fully prehensile tail acts as a fifth limb, gripping branches and even supporting the animal's full weight while it reaches for food. Top speeds of around 16 km/h are reached only in short bursts, as their leaf-based diet leaves little energy to spare. They almost never come down to the ground, staying safe among the high branches.

Social structure

Howlers live in troops of around 6 to 15 individuals, usually including several adults of both sexes along with juveniles and infants. Rather than fighting over territory, neighbouring groups rely on their loud calls to keep their distance. Within the troop, grooming and vocal exchanges help maintain social bonds. Males are larger than females and take the lead in the roaring contests that define howler society.

Reproduction and lifespan

Females give birth to a single infant after a gestation of around six months, and the newborn clings to its mother as she moves through the trees. Young howlers are weaned gradually and learn which leaves and fruit are safe to eat by watching the adults. In the wild, howler monkeys live around 15 to 20 years. Their slow, energy-conserving lifestyle is reflected in their unhurried pace of breeding and growth.

Did you know? Howler Monkey facts

• Howler monkeys produce deep roars audible up to 5 km away thanks to an enlarged hyoid bone.
• Territory announcements between rival troops without physical fights.
• They usually flee; males may throw branches if approached closely.
• Conservation: Least Concern.

Diet & feeding

Howler Monkey feeds primarily as a leaves, fruit, flowers.

Adaptations

• The hyoid bone acts like a resonating chamber for territorial calls at dawn.
• Slow digestion limits activity — howlers rest up to 80% of daylight hours.

Behaviour & ecology

• The hyoid bone acts like a resonating chamber for territorial calls at dawn.
• Slow digestion limits activity — howlers rest up to 80% of daylight hours.

Communication

• Howler Monkey uses scent, posture, and vocal signals to mark territory and coordinate social behaviour.
• Communication intensity often peaks during breeding seasons and territorial disputes.

Habitat & range

Central and South American forests

Ecological role

Howler Monkey plays a recognised ecological role in central and south american forests.

Conservation status of the Howler Monkey

Sources & references

This guide is compiled and reviewed against established zoological and conservation references. Key sources for the Howler Monkey:

• IUCN Red List of Threatened Species

  Conservation status (Least Concern) reflects the IUCN Red List category for Alouatta spp..

• iNaturalist — observations & photos

  Search citizen-science observations and community IDs for Alouatta spp.. Useful for range checks and recent sightings — not a substitute for formal Red List status.

• GBIF — occurrence data

  Global Biodiversity Information Facility species search for Alouatta spp.. Explore published occurrence records used in range research.

• IUCN Red List — Alouatta spp..

  Conservation status (Least Concern) and population trends.

• Animal Diversity Web — Alouatta spp.. University of Michigan Museum of Zoology.

  Life history, morphology, and range.

• Global Animal Guide editorial standards

  How we research, source, review, and update every guide for accuracy.