WATCH: Orangutans bred in captivity released back into the wild

Training schools for orangutans form part of a project by the Frankfurt Zoological Society on the Indonesian island of Sumatra.

Orangutans bred in captivity are prepared for life in the wild and then released into the Bukit Tigapuluh National Park.

Around 170 of the animals have already been released as part of the project, with the aim of getting to double that number in order to create a self-sustaining population in the long term.