The overall aim of our rehabilitation programme is to release as many suitable orangutans as possible into areas where they have become extinct, or where the carrying capacity of the area is so low that the resident orangutans are at risk of extinction or inbreeding.
All IAR’s rehabilitation efforts are conducted in accordance with the IUCN Guidelines for the Reintroduction of Great Apes (2007). These guidelines stipulate that any great apes must only be reintroduced into areas where they will be protected and not at risk from any external threats.
The reintroduction process differs greatly depending on the age and background of the individual animal. Wild orangutans rescued from conflict situations or degraded habitats deemed healthy after a health check in the field, or at our centre, are released back into the wild as soon as possible, a process called ‘translocation.’ In this instance, the orangutans aren’t monitored post-translocation as they are still substantially wild and their period in care so short that there are not considered to be any impediments to their survival.
The second process is for animals that have been rescued from conflict situations, degraded habitat or the pet trade and have had to undergo a significant period of rehabilitation, and are released only after extensive pre-release monitoring and behavioural data collection and analysis has shown that they exhibit behaviour that mirrors wild orangutan behaviour. In these instances, orangutans are released and monitored for a period of two years, to ensure they are surviving in the wild, adapting to life in the wild, and determine how they are socialising with wild orangutans. Data is also collected on the phenology of the forest they are released in to determine if there is enough food for them to eat, and establish whether their presence is having any impact on the forest.
In both cases, it is imperative that forest is found in which to release them, and the forest has a population of wild orangutans small enough to cope with additional individuals and enough fruiting trees to sustain them. It must also, crucially, be protected, free of any external threats and our programme must have the support of the people living in the vicinity of the release site. While the political and social context of Indonesia means there are always threats to natural forests, IAR has conducted extensive surveys in the last few years and we now release our translocated orangutans into two areas; Gunung Tarak Nature Reserve and Bukit Baka Bukit Raya National Park.
Bukit Baka Bukit Raya National Park is a 181,000 hectare national park that has a very small and potentially non-viable resident wild orangutan population, which is in need of reinforcement. Most of the forest in this park is high elevation but there is sufficient low elevation forest to support an orangutan population. This lowland forest is contiguous with a larger area of forest, particularly across the provincial border in Central Kalimantan, and provides opportunity for future population growth and emigration. The high mountains of this area also provide a natural border to keep the founder population near the release site. It is also far enough from human dwellings, farms and roadways to minimise the chance of Human-Orangutan Conflict (HOC) occurring. Finally, and of great importance, this forest is already protected as a National Park and we have full support from the park authorities and the local people.
Gunung Tarak Nature Reserve stretches from the South East corner of Gunung Palung National Park down to the North East corner of the Sungai Putri forest. While its official area is 23,644.03 hectares, approximately 5000 hectares of this is being used for agriculture, or is open land. The remaining land is mostly secondary dry dipterocarp forest, and secondary swamp forest. Its location means it is an important buffer zone for the much larger Gunung Palung.