Indonesia Floods: 7% of World's Rarest Great Apes Killed in Extreme Rainfall
The Devastating Impact of Extreme Rainfall on Tapanuli Orangutans
Extreme rainfall and landslides fuelled by the climate crisis killed 7% of the remaining population of the world’s rarest great ape, a study has found, prompting fears for the species’ survival.
The Event Details
The research suggests 58 out of the remaining 800 critically endangered Tapanuli orangutans (Pongo tapanuliensis) were killed after more than 1,000mm (39in) of rain fell over four days in Indonesia’s North Sumatra province in November 2025. This equates to 11% of the local population and 7% of the entire species.
The Data Analysis
- 58 Tapanuli orangutans killed in the floods
- 800: remaining population of Tapanuli orangutans
- 7%: proportion of the world's rarest great ape population killed
- 11.7%: proportion of key forest habitat wiped out by landslides
The Impact Analysis
“It is tragic to lose so many apes in this way. In landscapes where populations are small and fragmented, this type of weather or climate event can have population-level consequences. It is extremely worrying for the future of this ape,” said Prof Serge Wich, a primatologist at Liverpool John Moores University and co-author of the study.
The Prediction
Previous research has suggested annual losses of 1% of the Tapanuli orangutan population would be sufficient to lead to eventual extinction. The Indonesian government has temporarily paused all major industrial activity in the Batang Toru area to give scientists the opportunity to investigate how best to secure the long-term survival of the Tapanuli orangutan.