There are just three orangutan species left in the wild, the Bornean, Sumatran and Tapanuli. This "person of the forest" is the largest arboreal mammal and the only great ape in existence in Asia. With long arms that may reach two metres in length, shaggy reddish-brown fur and grasping hands and feet, the orangutan swings slowly through the tree canopy of Borneo. When night approaches they make nests of vegetation to sleep in and occasionally smaller ones during the day to rest.

Male orangutans are evident by their large size (weighing up to 90 kilos, compared to 50 kilos for females), their cheek pads and throat pouch. Generally antisocial apes, their primary social structure consists of solitary males and subadults of both sexes and adult females with one or two juveniles. They are not territorial animals; however adult males are usually quite hostile towards one another.

Males in Sumatra sport moustaches and beards, as well as prominent throat sacs which they use to bellow and roar. The Sumatran species is also a little thinner, with longer faces and longer, paler hair on their bodies.

The discovery of the Tapanuli orangutan in 2017 marked the first time a new great ape species was introduced to science in almost 90 years. They have thicker, curlier hair than the other two species of orangutan, with males identified by their noticeably flatter cheek pads. Their “long call” – used to communicate with other orangutans when it is time to mate - is also noticeably distinct, as is their diet.