Mammals
Black Howler Monkey
Alouatta caraya · also called black-and-gold howler monkey
A booming howl rolls across the forest canopy as a jet-black male leads his golden-blonde troop mates through the trees, the extreme colour difference between the sexes making the black howler monkey one of the most visually striking primates in South America.
Overview
The black howler monkey, Alouatta caraya, is a leaf-eating primate native to rainforest and forest habitat across parts of Argentina, Paraguay, Bolivia, and Brazil. Its dramatic difference in coat colour between males and females, extremely loud amplified calls, and vulnerability to periodic yellow fever outbreaks make it one of the more visually and ecologically distinctive howler monkey species found anywhere in South America.
Two colours, one species
Few primates show as stark a visual split between the sexes as the black howler monkey, where a troop moving through the canopy can look at first glance like two entirely different species travelling together rather than a single social group.
Status
Least Concern, though periodic yellow fever outbreaks have caused significant regional population declines across parts of its range.
Black Howler Monkey: common questions
Why do male and female black howler monkeys look so different?
This species shows extreme sexual dichromatism, with males carrying a solid black coat while females and juveniles have a strikingly different golden-blonde coat, a colour difference dramatic enough that the two sexes can appear to be entirely different species at first glance.
How loud is the black howler monkey?
This species produces extremely loud howling calls, amplified through an enlarged hyoid bone in the throat, ranking among the loudest calls of any land animal in the Americas and used to advertise territory across considerable distances of forest.
Why do black howler monkey populations sometimes crash suddenly?
This species is highly susceptible to yellow fever, and periodic outbreaks of the disease have caused significant regional die-offs, since howler monkeys generally lack strong natural resistance compared with some other primate species exposed to the same virus.
How far south does the black howler monkey's range extend?
This species has the southernmost natural range of any howler monkey species, extending further into temperate parts of South America, including Argentina, than the more tropical ranges typical of its howler monkey relatives.