The mantled howler monkey is a truly arboreal species, quadrupedally walking and climbing through the canopy or suspending themselves below branches, hanging by the arms and anchoring themselves with their long tail whilst feeding (3). They often cross open areas between forest patches on the ground and are able to swim (3). They are active during the day and sleep on horizontal tree branches at night (3). This species spends much of its time foraging on leaves, fruit and flowers (5). Like all members of the genus Alouatta, the mantled howler monkey has very large salivary glands, which help it to break down the tannins in the leaves before they reach the gut (6).
The mantled howler monkey lives in groups usually numbering between 10 to 20 individuals, in which a distinct social hierarchy exists. There is an alpha male who has priority access to receptive females within the group (3) (5). Females form the stable core within a group, very rarely leaving once established (5).
Breeding occurs throughout the year but births are more common in late December and January (3) (5). A single young is produced after a gestation period of around six months (5) (6). The newborn infant is licked and carried by the mother (3). As it ages, the infant begins to ride around on its mother’s back, grasping the base of her tail with its own (5). For the first four months of life the young monkey will not venture further than two meters away from its mother (3). Sexual maturity is reached at 36 months in females and 42 months in males (5).