The Bukit Tigapuluh (BTP) ecosystem, located in the provinces of Jambi and Riau in Sumatra, is one of only two Sumatran orangutan reintroduction sites in the world. Sumatran orangutan populations are now considered Critically Endangered, and currently number less than 7% of what existed in 1900. With approximately only 6,300 left in the wild and hundreds being killed every year, it is imperative that viable released populations are built up outside of the troubled Aceh province.
The BTP ecosystem encompasses the largest remaining lowland forest block in Sumatra. The core area of the Bukit Tigapuluh forest block (144,000 ha) was declared as a national park in 1995. A survey in 2000 found that BTP was highly suitable habitat for the Sumatran orangutan. A conservative estimate for the Bukit Tigapuluh area, only taking the remaining primary forest into account, extrapolates a carrying capacity of approximately 750 orangutans. This amazing ecosystem is home to thousands of species including the reintroduced population of Sumatran orangutans as well as the Sumatran tiger and elephant- all critically endangered species.
Since 2002, more than 150 Sumatran orangutans have been transferred to and released into the BTP ecosystem. Orangutans entering the release programme have usually been orphaned and kept as pets, often in horrendous conditions. They must undergo extensive training including forest school so they can learn how to survive in their new jungle home before they are released. They must be able to recognise and eat a range of fruits, leaves and other important food sources such as termites and bark, make sleeping nests in the canopy at night and not come to the ground before they are considered suitable for release.
Extensive monitoring of orangutans occurs during and after the release process. Orangutans now have a small transponder inserted between their shoulder blades so they can be tracked using telemetry equipment well after their release to check on their progress. This has been a huge development in allowing longer term monitoring and assessment of released orangutans.
The recent estimated survival rate of released orangutans in BTP is approximately 70% which is excellent. Five orangutan infants have been born wild at the BTP release site after their mothers have been released, an exciting outcome. The release area is monitored by Wildlife Protection Units and many local people are employed by this programme.
Project Leader: Dr Peter Pratje