Heavy rains and landslides in Indonesia threaten Tapanuli orangutans with extinction
Kyiv • UNN
Cyclone Senyar on Sumatra has caused the deaths of 58 Tapanuli orangutans. The loss of 7% of the population threatens the complete extinction of the world's rarest great ape species.
Four days of extreme rainfall and landslides on the Indonesian island of Sumatra have pushed the world's rarest great ape species even closer to extinction, according to a study. This was reported by the BBC, according to UNN.
Details
Researchers estimate that the natural disaster last November killed 58 Tapanuli orangutans—about 7% of the total population, which numbers fewer than 800 individuals and is critically endangered.
These figures are conservative and do not account for damage to the forest canopy caused by the rains or the reduction in food availability, note the authors of the study published on Wednesday.
Cyclone Senyar devastated Sumatra in late November, causing Southeast Asia's deadliest natural disaster of 2025, which claimed more than a thousand lives.
According to the authors, the study's results indicate that extreme rainfall can directly threaten the survival of great ape populations.
However, the scale of the damage caused to the island's wildlife is much more difficult to assess.
Conservation experts previously noticed that sightings of Tapanuli orangutans dropped sharply after the storm, leading to speculation that the animals may have been swept away by floods and landslides.
Professor Erik Meijaard, executive director of Borneo Futures in Brunei and one of the study's authors, told the BBC back in December that Cyclone Senyar likely claimed the lives of about 35 orangutans. At the time, he called it a "serious blow to the population."
His new estimate—58 dead animals—significantly exceeds the previous one.
A few weeks after the cyclone, humanitarian workers told the BBC that in the village of Pulo Pakkat in the Central Tapanuli district, they found the body of an animal they believed to be a Tapanuli orangutan, partially buried in mud and timber.
Cyclone Senyar destroyed vast areas of forests on Sumatra.
The researchers noted that while the cyclone was an anomalous event, human-induced climate change played a significant role in its consequences.
They also emphasized that the frequency and intensity of extreme rainfall in the region are likely to continue increasing, posing a serious threat to the survival of Tapanuli orangutans and their habitat.
Studies show that the species, discovered only in 2017, could completely disappear if it loses more than 1% of its population annually.
The Indonesian government has temporarily suspended major projects in the Batang Toru area—a protected forest on Sumatra. This includes mining, oil palm plantation expansion, and hydropower projects. This has provided researchers with a rare opportunity to assess the environmental risks facing the species in more detail.
The authors of the report emphasize that the destruction caused by Cyclone Senyar demonstrates the extreme vulnerability of Tapanuli orangutans.