Sumatran orangutan - Threats

The Sumatran orangutan may decline by 97% over the next 50 years

Models based on rates of logging and its effect on orangutans reveal that habitat loss and other factors will push Sumatran orangutan populations toward extinction. The consensus is that Sumatran orangutan populations may decline by 50% in about a decade, by 97% in 50 years, and will eventually go extinct if habitat loss is not stopped.

If logging and hunting are stopped, only populations of 250 or more orangutans will have prospects of long-term viability. However, analysis of satellite imagery shows that between 1985 and 2001, approximately 560,893 ha of primary forest were lost. This represents about 37,400 hectares per year, and there are no signs that the trend is abating.

Habitat loss and degradation
Orangutan habitat in Sumatra is being lost at an extremely high rate. In North Sumatra, it is estimated that forest cover has reduced from around 82,000km² at the beginning of the last century to 26,000km² at the end of 1997. Much of this remaining forest may not be suitable for orangutans or is degraded to some extent.

An ill-conceived plan to build a major road through the Leuser Ecosystem, northern Sumatra, now threatens to fragment and open access to orangutan habitat. The road cuts through the Leuser Ecosystem in at least nine places and through additional orangutan habitat units further north. Because Environmental Impact Assessments (EIAs) were not carried out, the sections of the road that cross through protected areas are therefore illegal.

It is predicted that in places where the road intersects forested areas, illegal logging will happen at a massive scale, followed by settlements within some of the largest expanses of Sumatran orangutan habitat. The project is progressing despite proof that the conservation of the Leuser Ecosystem creates the conditions for the long-term sustainable development of the surrounding region of Aceh.
Find out more about habitat loss and degradation

Hunting
In Batang Toru and east Sipirok areas, it has been reported that orangutans are eaten.