Borneo's Orangutan Survival Foundation runs a sanctuary in Central Kalimantan, rescuing the endangered animals whose habitat is threatened by plantations and logging concessions.
Many of the animals rescued are very young. Local farmers often kill their parents for entering plantations in search of food.
Orphaned animals need several years of training to survive alone in the forest. Each day they are taken to the forest for activities to help them find food and develop their agility.
The centre's staff hide fruit in the branches of trees to help the orangutans learn where to look for it.
Their human trainers form close bonds with the animals they look after.
The workers here are all local people, and work to raise awareness about the need to preserve the forest.
A clinic is on site for sick animals. Hepatitis and diarrhoea are among the diseases being treated.
These newly-rescued babies are being kept in quarantine before joining the others in forest training.
Grown animals, brought in from the wild, are also kept separate. The centre is over-crowded and some animals are kept in quarantine cages until space can be found.
Every animal who arrives is given a name, and files are kept on every aspect of their time here.
Every orangutan is put into a "family" of eight apes and two humans, so the youngest animals can develop as naturally as possible. (Words and pictures: Lucy Williamson)