The Guatemalan black howler is a species of howler monkey, a type of New World monkey, from Central America. It is the largest of the howler monkey species and one of the largest of the New World monkeys. Both males and females have long, black hair and a prehensile tail, while infants have brown fur. Males of the species have an enlarged hyoid bone near the vocal cords. This hyoid bone amplifies the male howler's calls, allowing it to locate other males without expending much energy. Howling is heard primarily at dawn and at dusk.
Guatemalan black howlers are found in Belize, Guatemala and Mexico, in and near the Yucatan Peninsula. They live in evergreen, semideciduous and lowland rain forests.
Guatemalan black howlers are diurnal and arboreal animals. They live in groups of generally one or two adult males, a few females, and juveniles. Groups generally have between 2 and 10 members, but groups as large as 16 members can also occur. They are territorial creatures and their home range is between 3 and 25 hectares. As with other howler monkey species, the majority of Guatemalan black howlers' day is spent resting. Eating makes up about a quarter of the day, moving about 10% of the day, and the remainder of the day is spent in socializing and other activities. In order to communicate with each other Guatemalan black howlers use different vocalizations. Adult males in a group often howl when approached by other males who may try to compete for the alpha rank in the troop. Howling is a loud and low call that can last for over an hour. The howls of females are sound different from those of males and they also can be heard in group howling.
Guatemalan black howlers are polygynous. This means that males mate with more than one female during the breeding season. These howler monkeys can breed year-round. Females give birth to a single infant after the gestation period that usually lasts around 180 days. The mother takes care of her baby alone 12 months after birth. She also protects her infant from predators and adult males. Other females in the troop do not help raise the infant. Females in this species reach reproductive maturity at 4 years of age, and males become reproductively mature at 6-8 years of age. Males leave their natal group upon reaching maturity, but females generally remain with their natal group.
Main threats to Guatemalan black howlers include habitat loss through deforestation, hunting for food and capture as pets. Another threat they suffer from is a disease - yellow fever epidemics.
The IUCN Red List and other sources don’t provide the number of the Guatemalan black howler total population size. Currently, this species is classified as Endangered (EN) on the IUCN Red List and its numbers today are decreasing.
Guatemalan black howlers disperse seeds of various plants they consume through their feces, thus highly benefiting the local ecosystem.