When healthy and able to survive in the forest on their own, the orangutans are released at the edge of Bukit Tigapuluh National Park. Monitoring their behaviour closely ensures a successful reintroduction.

When an orangutan is ready, it is tranquilized and taken to a predetermined release site at the edge of Bukit Tigapuluh National Park. The exact site is chosen according to the characteristics of the orangutan in question. If highly sociable for instance it might be taken to an area where we know there are a number of other orangutans at the time. If dangerous and aggressive, it might be taken further away from the center and deeper into the forest. As many as 10 people might take it in turns to carry the orangutan through the dense and undulating forest to the release site, in a small transport crate. The crate will then be placed near to a decent sized fruiting tree and the door opened. After their release, we follow the orangutans from dawn to dusk, recording their behaviour, range and tree use, diet and food intake, general activity and social interactions. These data can then be compared to wild orangutans and other rehabilitants to assess an individuals progress. Research and monitoring of this kind is essential to evaluate each orangutan's progress and hence the overall success of the reintroduction process. Using the information we obtain we are able to adapt and change procedures according to needs.

The site for the reintroduction center was chosen very carefully. Extensive field surveys and feasibility studies were undertaken in a number of potential locations by Dr Peter Pratje, and Bukit Tigapuluh National Park came out easily as the most suitable. The park itself covers approximately 130,000ha of lowland rainforest making it the largest protected area of lowland rainforest left in Sumatra! Even the highest peak is still below 700m above sea level meaning that 100% of it is useable orangutan habitat. Studies of the food resources available were also extremely favourable. The type and density of orangutan food trees was found to be comparable to, if not better than it is in the well known research station at Ketambe, in the north of the island, where orangutan densities reach around 5 per square kilometer.  Furthermore, at the time of Dr Pratje's surveys orangutans had not been reported in the area at all in recent memory. In fact there had been no recent records since orangutans were reported to be present in Jambi Province by some Dutch authors in the 1830's. Thus the Bukit Tigapuluh forests were concluded to be ideal for a lowland animal such as the orangutan and an ideal location to reintroduce them to.