Mantled Howler - Physical Description

Physical Description

The mantled howler's appearance is similar to other howler monkeys of the genus Alouatta except for coloration. The mantled howler is primarily black except for a fringe of yellow or golden brown guard hairs on the flanks of the body earning the common name “mantled” howler monkey. When the males reach maturity, the scrotum turns white. Females are between 481 and 632 mm (18.9 and 24.9 in) in body length, excluding tail, and males are between 508 and 675 mm (20.0 and 26.6 in). The prehensile tail is between 545 and 655 mm (21.5 and 25.8 in) long. Adult females generally weigh between 3.1 and 7.6 kg (6.8 and 17 lb), while males typically weigh between 4.5 and 9.8 kg (9.9 and 22 lb). Average body weights can vary significantly between monkey populations in different locations. The brain of an adult mantled howler is about 55.1 g (1.94 oz), which is smaller than that of several smaller monkey species, such as the white-headed capuchin.

The mantled howler shares several adaptations with other species of howler monkey that allow it to pursue a folivorous diet, that is, a diet with a large component of leaves. Its molars have high shearing crests, to help it eat the leaves, and males have an enlarged hyoid bone near the vocal cords. This hyoid bone amplifies the male mantled howler's calls, allowing it to locate other males without expending much energy.