Re-introduction of Bornean orang-utans to Meratus protected forest, East Kalimantan, Indonesia

First paragraph: The orangutan is the only great ape living in Asia and 90% of the population lives in the forests of Indonesia. There are two species of orangutan, the Bornean orangutan (Pongo pygmaeus, divided into 3 subspecies: P. pygmaeus morio, P. pygmaeus wurmbii and P.pygmaeus pygmaeus), and the Sumatran orangutan (Pongo abelii). Pongo pygmaeus is classified as endangered and Pongo abelii as critically endangered (IUCN Red Data List, 2008), and listed on CITES App. I. Habitat destruction and fragmentation are the greatest threats to wild orangutans and are responsible for the drastic reduction in their numbers. Over the past 20 years, 4 million ha (of a total 13 million) of orangutan habitat have been converted for agriculture and palm-oil plantations (UNEP, 2007). Wanariset Orangutan Reintroduction Project (WORP) was established in 1991 by the Balikpapan Orangutan Survival Foundation (BOSF). The project rescues and rehabilitates orphaned orangutans and releases them back to their natural habitat (Smits et al., 1995). Between 1991- 2008, WORP released more than 400 orangutans to two release sites; Sungai Wain and Meratus forest, East Kalimantan, Indonesia. At the end of 2009, 220 orangutans reside at the Wanariset Centre in Samboja (prerelease rehabilitation centre) in various stages of rehabilitation, destined for release (Siregar, 2009)