Largest tree-dwelling mammal

The largest arboreal mammal is the orangutan (Pongo) which lives in the canopy of tropical rainforests in Borneo and Sumatra, Indonesia. Bornean orangutan (P. pygmaeus), Sumatran orangutan (P. abelii) and Tapanuli orangutan (P. tapanuliensis) males typically weigh 83 kg (183 lb) and measure 1.5 m (5 ft) tall. They have opposable toes on their feet and use their arm span of approximately 2 m (6 ft 6 in) to swing between branches and feed off fruit, small leaves and tree-bark. Being lighter (37 kg or 81 lb), the females usually build nests in the trees, whereas the adult males sleep on the ground.

The Malay word "orang-utan" means "man of the forest". There are believed to be around 119,500 orangutans remaining in the wild, more than 85% of which are Bornean. The critically endangered Sumatran orangutan numbers approximately 14,000, while the only recently described Tapanuli species is limited to only around 800.