Orangutan Population Survey

Orangutan populations are calculated by surveying their nests. Initial surveys, such as those we conducted in the Sebangau and Rungan landscapes, can confirm the presence of significant orangutan populations. With long-term monitoring, we can map trends in population and assess the impacts of disturbance such as illegal logging, habitat loss and fire on orangutans.

We have been conducting orangutan population density and distribution surveys in Sebangau since 1995, by far the longest study of its kind. Our preliminary surveys established the presence of an estimated 6,000 orangutans in the Sebangau forest, the biggest population in lowland Borneo; a discovery that led to Sebangau being awarded National Park status in 2004.

Our expertise in orangutan population surveys has led to BNF being invited to join government-level strategic planning discussions to identify and prioritise critical orangutan habitat for protection. Our highly skilled team provides training for other research and conservation organisations, contributes to the designation of High Conservation Value forest and conducts landscape-wide surveys across Borneo.

There are three key objectives in conducting these surveys:

Understand how orangutans survive in logged and regenerating peat-swamp forest, including assessing the impacts of the 2015 and 2019 fires on the Sebangau National Park’s orangutan population;
Monitor the impacts of human activities and conservation actions on orangutan population density and distribution;
Demonstrate the presence of globally important orangutan populations in as yet unprotected areas of forest to push protection of this habitat to the top of the conservation agenda.

Orangutan population surveys are the cornerstone for identifying priority habitat for protection

Data from our long-term monitoring in Sebangau have demonstrated the shifts and changes in orangutan population over a time period that has seen significant disturbance of the habitat. This allows us to assess the impacts of our conservation efforts to support the forest’s recovery from such disturbance and to protect orangutans.

Between 2017 and 2019, we conducted the first ever orangutan population surveys across the Rungan Landscape, identifying a population of 2,220 to 3,275 orangutans – significantly higher than previous estimates, and potentially one of the largest unprotected orangutan populations in the world. As in Sebangau National Park, these data represent a compelling argument for the protection of crucial orangutan habitat across the landscape.

Our orangutan population density and distribution surveys will continue in the Sebangau and Rungan landscapes, and will be an essential component of our research and conservation strategy for Barito Ulu.

Estimated Pongo pygmaeus wurmbii population

0

individuals of P.p wurmbii remaining in West and Central Kalimantan

> 0

orangutans in Sebangau Forest

~ 0

orangutans in the Rungan Landscape

> 0

years of studying orangutans