Are Howler Monkeys Really as Loud as Their Name Suggests?

Howler monkeys have enlarged hyoid bones in their necks that help them produce loud vocalizations. Groups of males generally belt out loud guttural growls, or howls, at dawn and dusk, possibly as a way to protect their boundaries and guard their mates. Howler monkeys are considered to be the world's loudest land animals, and their chorus can be heard clearly through the dense rainforest from as far away as three miles (4.8 km), according to Guinness World Records.

Can you hear me now?

• Male howler monkeys have large throats and specialized, shell-like vocal chambers that help them crank up the volume. The message to other monkeys is clear: Back off.
• Howler monkeys are among the largest of the New World monkeys and one of only a few species of nest-building monkeys.
• These monkeys are native to South and Central American forests. They face threats from humans such as habitat destruction and being captured for relocation to zoos.

Frequently Asked Questions

How loud can howler monkeys actually get?

Howler monkeys are renowned for their powerful vocalizations, which can reach up to 90 decibels, about as loud as a lawnmower. According to the Guinness World Records, their calls can be heard clearly for 3 miles (4.8 km) in dense rainforest. This volume is achieved through a specialized, enlarged hyoid bone in their throat, which amplifies the sound.

Why do howler monkeys make such loud noises?

Howler monkeys use their loud calls primarily for territorial purposes and communication. The calls serve to warn other troops of their presence, thus avoiding physical confrontations. Additionally, the howls can help group members stay in contact in the dense forest canopy and may also play a role in attracting mates.

Are all howler monkey species equally loud?

While all howler monkey species are known for their volume, there is variation among species. The black howler monkey (Alouatta caraya) is often cited as the loudest. However, the loudness can also depend on factors like the individual's size, the structure of the forest, and the context of the call.

What time of day are howler monkeys most vocal?

Howler monkeys are most vocal at dawn and dusk. These peak calling times coincide with the times when the troop is waking up or settling down for the night. The dusk calls may also serve to establish the sleeping location of the troop and ensure that all members are accounted for.

Can the howl of a howler monkey be harmful to humans?

The volume of a howler monkey's call is not typically harmful to humans, as it is not loud enough to cause hearing damage unless one is exposed at a very close range for a prolonged period. However, their howls can certainly be startling and may disrupt the sleep of people living nearby.

Do howler monkeys use their loud calls for anything other than communication?

Beyond communication and territorial displays, the loud calls of howler monkeys have been suggested to play a role in deterring predators. The impressive volume of their howls can make them seem larger and more formidable, potentially discouraging attacks from animals like jaguars and birds of prey.