Guatemalan Black Howler, Alouatta pigra

The Guatemalan black howler (Alouatta pigra), also known as the Yucatan black howler, is a species of howler monkey that is native to Central America. Its range includes Mexico, Belize, Guatemala, and areas near the Yucatan Peninsula. It prefers to live in semi deciduous, evergreen, and lowland rainforests.

The Guatemalan black howler is one of the largest of all New World monkeys, and the largest of all howler monkeys. Males are typically larger than females, weighing up to 25 pounds, while females weigh an average of 14 pounds. Adults can reach a body length between 1.7 and 2.1 feet, with a prehensile tail length of up to 2.5 feet. Both males and females have long, black fur, while young black howlers are typically dark brown in color. Males bear an enlarged hyoid bone, located near the vocal chords, which allow their calls to reach farther distances while using less energy. This is vital because leaves, which comprise most of the monkey’s diet, are not high in nutrition, and howling occurs twice a day in the evening and morning.

Guatemalan black howler monkeys will form groups that can contain between one or two males and at least one female per male. These groups can grow to have 16 individuals, although ten is the average number. They are nocturnal and reside in trees, making them arboreal. Most of their day is spent resting, although they will spend up to a quarter of their time eating. The rest of the day is either spent moving about or partaking in social activities. Males will leave their birth once they reach four years of age, while females tend to remain in their birth groups.

As is typical to howler monkeys, the Guatemalan black howler has adapted to eating a main diet of leaves. It will also consume fruit and occasionally flowers. During many seasons, these monkeys will consume materials from the breadnut tree, comprising up to 86 percent of its diet. This monkey can live as long as twenty years.

The Guatemalan black howler resides with the mantled howler on the edges of its Mexico and Guatemala range. It is thought that this occurs because of a gap in migration of the species in the late Miocene or Pliocene. After the ancestor of the Guatemalan black howler migrated from South America to Central America, the Isthmus of Panama closed because of rising sea levels. Later, the ancestor of the mantled howler migrated into Central America and outcompeted the Guatemalan black howler ancestor. It is thought that this is the reason behind the black howler’s limited range.

It is thought that the populations of the Guatemalan black howler may decline up to sixty present over the next thirty years, and so it is listed as “Endangered” on the IUCN Red List. The major threats to this species include habitat destruction, capture as pets, and hunting.

Image Caption: Guatemalan Black Howler, Alouatta pigra. Credit: Ruestz/Wikipedia(CC BY-SA 3.0)