Claus Meyer / Humboldt's Woolly Monkey (Lagothrix lagotricha), Amazon, Brazil

Claus Meyer / Humboldt's Woolly Monkey (Lagothrix lagotricha), Amazon forest, Brazil

Pete Oxford / Humboldt's Woolly Monkey (Lagothrix lagotricha) hanging in a rainforest tree using its prehensile tail, Amazon, South America

Pete Oxford / Humboldt's Woolly Monkey (Lagothrix lagotricha) portrait, Amazon, South America

Norbert Wu / Humboldt's Woolly Monkey (Lagothrix lagotricha), Amazon rainforest, Brazil

Flip de Nooyer / Humboldt's Woolly Monkey (Lagothrix lagotricha) hanging by his tail, Brazil

Nick Gordon / Common woolly monkey (Lagothrix lagoticha) in canopy. Brazil, Amazonia, South America

Murray Cooper / Humboldt's Woolly Monkey (Lagothrix lagotricha), Ecuador

Murray Cooper / Humboldt's Woolly Monkey (Lagothrix lagotricha), Ecuador

Kevin Schafer / Humboldt's Woolly Monkey (Lagothrix lagotricha), Manu National Park, Peru

Kevin Schafer / Humboldt's Woolly Monkey (Lagothrix lagotricha), Manu National Park, Peru

Pete Oxford / Humboldt's Woolly Monkey (Lagothrix lagotricha) mother and baby climbing tree, Yasuni National Park, Amazon, Ecuador

Pete Oxford / Humboldt's Woolly Monkey (Lagothrix lagotricha) mother and baby climbing tree, Yasuni National Park, Amazon, Ecuador

Thomas Marent / Humboldt's Woolly Monkey (Lagothrix lagotricha) resting, Amacayacu National Park, Colombia

Claus Meyer / Humboldt's Woolly Monkey (Lagothrix lagotricha) sitting in tree, Amazon ecosystem, Brazil

Tim Laman / Poeppig's woolly monkey (Lagothrix poeppigii) leaping from tree in rainforest, Tiputini Biodiversity Station, Orellana Province, Ecuador. Endangered.

Tim Laman / Woolly monkey (Lagothrix poeppigii) female, leaping from tree, Tiputini Biodiversity Station, Orellana Province, Ecuador.

Tim Laman / Woolly monkey (Lagothrix poeppigii) juvenile, swinging from branch, Tiputini Biodiversity Station, Orellana Province, Ecuador.

Tim Laman / Woolly monkey (Lagothrix poeppigii) male, resting on branch, Tiputini Biodiversity Station, Orellana Province, Ecuador.

Joel Sartore / Photo Ark / Silvery woolly monkey (Lagothrix poeppigii) portrait, Amazon Shelter, a wildlife rescue, rehabilitation and release center, Tambopata, Peru. Captive. Endangered.

Joel Sartore / Photo Ark / Silvery woolly monkey (Lagothrix poeppigii) portrait, Amazon Shelter, a wildlife rescue, rehabilitation and release center, Tambopata, Peru. Captive. Endangered.

Joel Sartore / Photo Ark / Silvery woolly monkey (Lagothrix poeppigii) sitting holdings its tail, portrait, Amazon Shelter, a wildlife rescue, rehabilitation and release center, Tambopata, Peru. Captive. Endangered.

Joel Sartore / Photo Ark / Gray woolly monkey (Lagothrix cana) male juvenile, sitting and vocalising, portrait, Mantenedor da Fauna Silvestre Cariua, Manaus, Brazil. Captive.

Joel Sartore / Photo Ark / Gray woolly monkey (Lagothrix cana) male juvenile, head portrait, Mantenedor da Fauna Silvestre Cariua, Manaus, Brazil. Captive.

Joel Sartore / Photo Ark / Gray woolly monkey (Lagothrix cana) male juvenile, sitting holding its tail, portrait, Mantenedor da Fauna Silvestre Cariua, Manaus, Brazil. Captive.

Joel Sartore / Photo Ark / Gray woolly monkey (Lagothrix cana) male juvenile, sitting holding its tail, portrait, Mantenedor da Fauna Silvestre Cariua, Manaus, Brazil. Captive.

Joel Sartore / Photo Ark / Gray woolly monkey (Lagothrix cana) male juvenile, sitting holding its tail, portrait, Mantenedor da Fauna Silvestre Cariua, Manaus, Brazil. Captive.

Joel Sartore / Photo Ark / Peruvian woolly monkey (Lagothrix cana) female juvenile, portrait, showing severe growth deformities due to poor nutrition after being reared as a pet, Cetas-IBAMA wildlife rehabilitation centre, Mana...

Joel Sartore / Photo Ark / Peruvian woolly monkey (Lagothrix cana) female juvenile, feeding, showing severe growth deformities due to poor nutrition after being reared as a pet, Cetas-IBAMA wildlife rehabilitation centre, Manau...

Joel Sartore / Photo Ark / Peruvian woolly monkey (Lagothrix cana) female juvenile, portrait, showing severe growth deformities due to poor nutrition after being reared as a pet, Cetas-IBAMA wildlife rehabilitation centre, Mana...

Lucas Bustamante / Common woolly monkey / Brown woolly monkey (Lagothrix lagothricha) climbing in tree with infant on back, tail entwined with adult's, Yasuni National Park, Orellana, Ecuador.

Mark Bowler / Common woolly monkey (Lagothrix lagothricha) baby, Maijuna Indigenous Community, Rainforest, Sucusari, Rio Napo, Loreto, Peru. January 2013.

Mark Bowler / Woman holding Common woolly monkey (Lagothrix lagothricha) on the left Poepigg's woolly monkey (Lagothrix poepiggii) on the right. Both species from Maijuna Indigenous Community, different species on...

Pete Oxford / Huaorani Indian, Tage Kaiga, hunting in Amazon rainforest, dead Woolly monkey (Lagothrix sp) slung over shoulder, shot using blowgun. Members of this Indian tribe were uncontacted until 1956. Yasuni N...

Oscar Dewhurst / Grey woolly monkey (Lagothrix cana) sitting in the Peruvian cloud forest. Cusco, Peru. September.

Konrad Wothe / Grey woolly monkey (Lagothrix cana) hanging upside down with baby, rainforest, Amazon, Brazil.

Konrad Wothe / Grey woolly monkey (Lagothrix cana) with baby, rainforest, Amazon, Brazil.