Jakarta, ThedailyID — Indonesia’s Sumatran orangutan population has fallen nearly 20% over the past 12 years, raising concerns over the species’ future.
A recent survey estimated that only 11,694 Sumatran orangutans remained between 2021 and 2023. The figure fell from an estimated 13,846 individuals in 2011.
Researchers from IPB University said the decline amounts to about 19.5% over 12 years. That equals an average annual decline of around 1.8%.
Dede Aulia Rahman, a researcher at IPB University’s Department of Forest Resources Conservation and Ecotourism, described the situation as a conservation emergency.
The largest remaining population lives in the Leuser Ecosystem, which supports around 84% of all Sumatran orangutans.
The situation is even more critical for the Tapanuli orangutan (Pongo tapanuliensis). Researchers estimate that only around 716 individuals remain across three metapopulations in the Batang Toru Ecosystem.
“Those numbers are very serious because orangutans cannot recover their populations quickly,” Dede said, according to IPB University.
Nearly 94,400 Hectares of Forest Lost
Habitat loss remains one of the biggest threats to orangutan populations. Research found that forest loss explains around 76% of population changes between different metapopulations.
From 2011 to 2023, about 94,399 hectares of forest disappeared across orangutan habitats.
Several factors contributed to the loss, including plantation expansion, infrastructure development, mining and illegal encroachment.
However, habitat loss is not the only threat. Human-orangutan conflict, hunting, illegal wildlife trade and habitat fragmentation also continue to put pressure on the species.
Forest fragmentation can push orangutans into plantations and human settlements. This increases the risk of conflict, capture and killing.
Orangutans also reproduce slowly, making population recovery difficult. Females generally give birth to one infant every seven to nine years.
Dede warned that local extinction risks will increase if habitat loss and human-caused deaths continue.
Conservation efforts therefore need to combine habitat protection, ecological corridor restoration and measures to reduce orangutan deaths.
Dede also stressed the importance of cooperation between the government, businesses, academics, local communities and conservation organizations to protect the remaining populations.
