Pictures of black and gold howler monkeys (often known as simply the Black Howler, Alouatta caraya). The male is black, the female is gold.
The Black Howler monkey has a loud, low, roaring call that can be heard over long distances, announcing a group's presence and territorial boundaries to neighboring howler groups. Howlers guard their territory against all outsiders: humans lurking below to observe the monkeys may find themselves wearing a handful of food, or worse, if they get too close.
Only adult males are black. Females and all infants are blond. Male babies change color as they grow.
Black Howler monkeys live in South America: Brazil, Paraguay, and Argentina.