Sumatra’s Tapanuli Orangutan Population Falls to 716 Individuals. Is Everything OK?

By Junaidi Hanafiah for Mongabay Indonesia, August 5, 2026

The current estimated number of Tapanuli orangutans (Pongo tapanuliensis) in the wild on Indonesia’s Sumatra Island is around 716 individuals. The estimate is the result of a survey conducted throughout 2021–2023 across the Batang Toru region of North Sumatra.

The findings were published in the June 20, 2026, issue of the journal Global Ecology and Conservation titled “Population Status of Sumatran and Tapanuli Orangutans: A Comprehensive Assessment 2021–2023.”

The survey, led by Adhi N. Hadi and Julius P. Siregar, along with dozens of researchers from Indonesia, the UK, and Germany, used 208 nest transects, spanning 198 kilometers, in the habitat of Sumatran and Tapanuli orangutans.

In Batang Toru, researchers followed 57 kilometers of transects and recorded 330 nests, which were analyzed using distance sampling and spatial modeling to estimate the population.

“The results show the Tapanuli orangutan population is estimated at 716 individuals, all living within the 102,185-hectare Batang Toru region. A total of 514 individuals (72 percent) are in West Batang Toru, 159 individuals in East Batang Toru, and 43 individuals in Sitandiang–Sibualbuali, with an average density of 0.70 individuals per square kilometer,” wrote Adhi and colleagues.

Compared to the 2011 estimate of around 767 individuals, this number represents a decrease.

“However, comparisons must be made with caution because the methods and scope of previous surveys were different.”

This study also confirms that Tapanuli orangutans have a very small demographic buffer, so even the smallest mortality can threaten population continuity.

“Orangutan density is highly dependent on intact forests, while human pressures such as encroachment, conflict, hunting, and habitat loss remain the main threats.”

The research explains that approximately 78.6 percent of the population lives in protected forest areas, with only 9.5 percent in conservation areas. The remainder are in production forests and other land use areas (APL) which are vulnerable to land conversion.

“Conservation strategies must focus on zero additional mortality or preventing every orangutan death.” …Read the whole report at https://mongabay.co.id/2026/08/05/populasi-orangutan-tapanuli-sekitar-716-individu-apakah-baik-baik-saja/.