The howler monkey belongs to the Genus Alouatta and there are 15 known species. They are among the largest of the New World monkeys. Depending on the species, they have either a black or brown coarse coat. They have a prehensile (capable of grasping) tail, which they use as an anchor when sleeping, as well as to aid in traversing through the forest. Their enlarged throats allow them to emit their loud distinctive calls, that can travel up to 5 km.
These monkeys are native to a variety of forests in Central and South America. Home ranges can vary greatly depending on habitat type. Group ranges will often overlap, but they use their “long calls” to keep their distance. This call is the loudest sound made by a land animal and serves to avoid aggressive encounters with other troops. Avoiding these encounters helps conserve energy, which is important for a howler monkey, as its diet mostly consists of leaves (a poor energy source). A howler monkey will spend 80% of the day at rest.
Groups of howler monkeys comprise of one alpha male, few other males and then several females and rarely exceeds 15 members. At 3-5 years old females often leave their birth troop to form their own. Whereas males often fight their way into other groups at a slightly later age. Mantled howler monkeys are an exception where groups can be as large as 40, and both male and female members are likely to join other troops.
Ancient Mayan civilizations saw these monkeys as divine creatures and worshipped howler monkey gods. Nowadays, these monkeys are frequently traded illegally as pets in South and Central America. Due to their relatively fast reproduction rate the howler monkey is less threatened by hunting and capture for the pet industry compared to other primate species. However, habitat destruction for agriculture and cattle grazing threatens their existence. Zoonotic diseases, such as yellow fever, are also depleting population sizes.
In 2015, five howler monkeys, who were rescued from animal traffickers, were re-introduced in Tijuca Forest, Brazil. They had disappeared from the forest, in the city of Rio de Janeiro, more than 100 years ago. The Tijuca Forest, known for Christ the Redeemer, is one of the world’s largest urban woodlands, but due to environmental degradation, has lost its fauna. The re-introduced monkeys will play a vital role in seed dispersal. Other conservation initiatives stem from Conservation Leadership Programme who are supporting projects to conserve the endangered Caatinga howler monkey, by preserving habitat in its original geographical range to promote population recovery.
Written by Emily Elmer – Wildlife Conservation Today Contributor