Black-and-gold Howler

Identification

The black howler is among the largest New World monkeys and one of nine species in the Alouatta genus. This species is strikingly sexually dimorphic: adult males are entirely black, while females and infants of both sexes display golden colouring, creating the distinctive black-and-gold appearance reflected in their name. Males are considerably heavier than females, weighing 6–7.7 kg compared to their lighter-weight counterparts. A notable anatomical feature is the enlarged hyoid bone in males, which functions as a resonating chamber for their famous vocalizations.

Range & Habitat

Black howlers are distributed across South America, occurring in Paraguay, southern Brazil, eastern Bolivia, northern Argentina, and occasionally Uruguay. They are predominantly arboreal, rarely descending to the ground. Well-conserved forests, such as those along the Paraná River in Brazil, support higher densities of these monkeys. They typically inhabit forested canopies where their prehensile tails—featuring bare patches of skin underneath—provide excellent climbing versatility and secure anchoring among branches.

Behaviour & Diet

Black howlers are renowned for their powerful vocalizations, with their distinctive howls audible up to two kilometres away. These calls serve as territorial displays and help regulate spacing between groups. The monkeys vocalize primarily around dawn. They are among the least active primates, spending 60–70% of their day resting or sleeping, though activity levels vary seasonally. Their diet is primarily folivorous, supplemented with fruits, figs, mosses, bark, seeds, and flowers. Howlers possess specialized digestive systems and strong molars enabling them to process mature leaves efficiently. During winter months, when fruit is scarce, they consume more leaves and are correspondingly less active.

Best Time & Places to See It

Listen for black howlers at dawn, when their vocalizations are most frequent and carry considerable distances through the forest. The Upper Paraná River region of southern Brazil offers excellent opportunities for observation, as well-conserved forests there support stable populations. Group sizes typically range from 6–18 individuals in optimal habitat. Patience and early morning expeditions significantly increase your chances of encountering these remarkable primates.

Photography Tips

The striking sexual dimorphism of black howlers offers compelling photographic contrast: capture the jet-black males alongside golden females and infants for dramatic compositional variety. Early light at dawn, when howling occurs, provides optimal conditions for both photography and audio recording. Their largely sedentary nature—spending most hours resting—offers patient photographers extended opportunities for sharp, detailed shots in the canopy. A telephoto lens is essential, as these arboreal monkeys remain elevated in forest layers.