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Animal Facts for the Howler Monkey

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Howler monkeys (Alouatta caraya) are large New World monkeys native to the savannas and forests of South America. They are named for their distinctive loud call, which can be heard up to three miles away, even through their densely-forested habitat. This low-pitched, guttural howl is the loudest vocalization made by any New World animal.

Range and Habitat

Howler monkeys are native to the central parts of South America, and can be found in Bolivia, Brazil, Argentina and Paraguay. They spend almost all of their time in the trees, and thus require a heavily-forested habitat with wide range of plant life. These monkeys can be found in a number of forested habitats, including tropical rainforests, evergreen forests and seasonal deciduous forests bordered by pockets of open savanna.


Howler monkeys are the largest New World monkeys, reaching heights of 2 to 4 feet and weighing up to 22 pounds. These monkeys have large necks and jaws that allow them to create their loud vocalizations. Males and females are very different in appearance; females' fur color can range from yellow to olive brown, whereas males have fur that is all black. Males also are larger than females. All howler monkeys have long, prehensile tails that aid them in grasping limbs and moving through the canopies.


Howler monkeys spend the majority of their days quietly lounging among branches in social groups, called troops, that can number between 5 and 8 individuals. Howler monkeys typically will howl only during the mornings and evenings, to make neighboring troops aware of their presence. These howling sessions involve the entire howler monkey troop. Though they are territorial animals, howler monkeys do not tend to engage in overt conflict with nearby troops and in some cases may share an overlapping territory.


Howler monkeys primarily eat leaves, which provide for their nutritional and water needs. Occasionally, howler monkeys will feed on fruits, buds, seeds, moss and flowers to supplement their diet. Unlike other species of New World monkeys, howler monkeys' diet comprises mature leaves, though their preference is for young leaves. According to the IUCN Red List of Threatened Species, this flexibility in diet has helped the howler monkey to inhabit a wide range of habitats.


Though howler monkeys are considered by the IUCN Red List of Threatened Species to be a species of “Least Concern,” habitat loss due to clear cutting and logging to make room for agriculture and grazing has led to a decline in some populations of this species, especially those in the Argentinean provinces of Misiones, Salta, Formosa and Corrientes. However, howler monkeys' habitat overlaps with several protected areas and their adaptability to new environments makes them unlikely to see significant population losses.