Suzi Eszterhas / Bornean Orangutan (Pongo pygmaeus) next to signs which say 'Silence please. Respect the orangutans' and 'No Smoking' Tanjung Puting National Park, Borneo, Indonesia.

Gerry Ellis / Orangutan (Pongo pygmaeus) sub-adult male in trees in haze caused by forest clearing, West Kalimantan, Borneo, Indonesia. October, 2015

Sean Crane / Orangutan (Pongo pygmaeus) juvenile investigating camera, Tanjung Puting National Park, Borneo, Indonesia

Roland Seitre / Orangutan (Pongo pygmaeus) female, native to Borneo

Thomas Marent / Orangutan (Pongo pygmaeus) female with baby on back, Camp Leaky, Tanjung Puting National Park, Indonesia

Konrad Wothe / Orangutan (Pongo pygmaeus) orphans embracing, Borneo, Malaysia

Gerry Ellis / Orangutan (Pongo pygmaeus) hanging on tree, Sepilok Forest Reserve, Sabah, Borneo

Gerry Ellis / Orangutan (Pongo pygmaeus) mother and baby, Borneo

Konrad Wothe / Orangutan (Pongo pygmaeus) infant hanging from branch, Borneo

Konrad Wothe / Orangutan (Pongo pygmaeus) bathing in river while hanging upside-down from vine, Gunung Leuser National Park, Sumatra, Indonesia

Gerry Ellis / Orangutan (Pongo pygmaeus) pair playing in trees, Borneo

Konrad Wothe / Orangutan (Pongo pygmaeus) drinking from river while hanging upside-down from vine, Gunung Leuser National Park, Sumatra, Indonesia