Changes

In Sabah, genetic studies indicate that over the past two centuries, human activities have led to the loss of more than 90% of the original orangutan population (Goossens et al. 2006). The state of Sabah has witnessed the highest rate of forest loss in Borneo, with a 39.5% decrease in forest cover from 1973 to 2010, primarily affecting the eastern lowland forests, a favored orangutan habitat (Gaveau et al. 2014).  

In Sabah, genetic studies indicate that over the past two centuries, human activities have led to the loss of more than 90% of the original orangutan population (Goossens et al. 2006). The state of Sabah has witnessed the highest rate of forest loss in Borneo, with a 39.5% decrease in forest cover from 1973 to 2010, primarily affecting the eastern lowland forests, a favored orangutan habitat (Gaveau et al. 2014).  

In Kalimantan, orangutan populations face similar threats, including hunting pressure, forest fires, and conversion of forests to agricultural land. Areas in East Kalimantan inhabited by orangutans exhibit a high risk of conflict, largely driven by rapid conversion of natural land cover to plantations. The subspecies is rapidly decreasing, with climate change and land-use alterations expected to exacerbate habitat loss (Struebig et al. 2015). Fires have also significantly contributed to declines; for instance, Kutai National Park lost 90% of its area to extensive fires in 1983 and 1998, resulting in a drastic reduction of the orangutan population from around 4,000 individuals in the 1970s to a mere 600 (Rijksen and Meijaard 1999, Wich et al. 2009).

In Kalimantan, orangutan populations face similar threats, including hunting pressure, forest fires, and conversion of forests to agricultural land. Areas in East Kalimantan inhabited by orangutans exhibit a high risk of conflict, largely driven by rapid conversion of natural land cover to plantations. The subspecies is rapidly decreasing, with climate change and land-use alterations expected to exacerbate habitat loss (Struebig et al. 2015). Fires have also significantly contributed to declines; for instance, [[Kutai National Park]] lost 90% of its area to extensive fires in 1983 and 1998, resulting in a drastic reduction of the orangutan population from around 4,000 individuals in the 1970s to a mere 600 (Rijksen and Meijaard 1999, Wich et al. 2009).

The illegal killing of Northeast Bornean orangutans is also a main contributor to their population decline. Interview surveys conducted in Kalimantan have unveiled that several thousand individuals are slaughtered annually for purposes such as meat consumption, conflict mitigation, or other motives (Davis et al. 2013). Overall mortality rates for Bornean Orangutans in Kalimantan appear to far surpass the maximum sustainable rates for this species, known for its slow reproductive rate (Marshall et al. 2009, Meijaard et al. 2011).

The illegal killing of Northeast Bornean orangutans is also a main contributor to their population decline. Interview surveys conducted in Kalimantan have unveiled that several thousand individuals are slaughtered annually for purposes such as meat consumption, conflict mitigation, or other motives (Davis et al. 2013). Overall mortality rates for Bornean Orangutans in Kalimantan appear to far surpass the maximum sustainable rates for this species, known for its slow reproductive rate (Marshall et al. 2009, Meijaard et al. 2011).