Ernie Janes / Black howler (Alouatta caraya) male and female, captive, occurs in Brazil and Paraguay. With digitally added leaf pattern.

Bernard Castelein / Bolivian red howler (Alouatta sara), Pampas del Yacuma Protected Area, Bolivia

Suzi Eszterhas / Colombian red howler monkey (Alouatta seniculus) mother and baby in tree. Northern Colombia.

Ernie Janes / Black howler (Alouatta caraya) captive, occurs in South America.

Kevin Schafer / Guatemalan Black Howler Monkey (Alouatta pigra) calling, Community Baboon Sanctuary, Belize, Central America. Endangered species.

Kevin Schafer / Guatemalan Black Howler Monkey (Alouatta pigra) climbing, Community Baboon Sanctuary, Belize, Central America. Endangered species.

Juan Carlos Munoz / Black howler monkeys (Alouatta caraya) male and two females calling from tree, captive, Apenheul Park, Netherlands.

Ernie Janes / Howler monkey (Alouatta caraya) resting in tree, Costa Rica.

Oscar Dewhurst / Purus red howler monkey (Alouatta puruensis) sitting in the rainforest canopy. Madre de Dios, Peru. April. Cropped

Ernie Janes / Black howler (Alouatta caraya) male female pair. Captive, occurs in South America, with digitally added leaf pattern.

Bernard Castelein / Bolivian red howler (Alouatta sara), female and juvenile, Pampas del Yacuma Protected Area, Bolivia