Howler monkeys are found in the forests of Bolivia, Paraguay, southern Brazil, and northern Argentina. These monkeys are arboreal, spending most of their time in the tree canopy where they engage in social activities, feed, and rest with groups of up to 30 individuals. They rarely descend to the ground.

Howler monkeys have a prehensile tail, which is essential for movement and balance. This tail also serves as an anchor when they rest in trees.
Their diet consists mainly of leaves, and due to the high fibre content of their food, howler monkeys spend up to 70% of the day resting while digesting. This diet of leaves, including both mature and young, fibrous material, is crucial for their survival, providing them with a steady food source.

The black howler monkey is currently classified as Near Threatened on the IUCN Red List. This species is widely distributed in several national parks, and it has demonstrated a capacity to adapt to new and fragmented habitats. However, its population is declining due to habitat destruction and hunting.

True to its name, the howler monkey is incredibly vocal. Their calls, amplified by a specialised voice box, can be heard from up to five kilometres away. These calls are used to mark territorial boundaries, with howling sessions between troops helping to define and defend their territories.

Howler monkeys were introduced to Fota Wildlife Park in 2010. The first howler monkey born at the park, Jamie, arrived in 2011. This species is unique at Fota for its willingness to swim. Howler monkeys at the park are vocal, and the sound of the train passing by often triggers a howling session, particularly from the dominant mating pair.