Scientists warn Cyclone Senyar may have pushed Tapanuli orangutan closer to extinction

Scientists fear that Cyclone Senyar, which made landfall on November 25, may have swept away a significant number of Tapanuli orangutans, after a carcass of the critically endangered great ape was found following severe flooding.

The Tapanuli orangutan was formally recognised as a distinct species in 2017 and is confined to a small region of Sumatra in Indonesia. Conservationists estimate that fewer than 800 individuals remain in the wild, making it the rarest great ape species on Earth.

According to a report by news website BBC, these orangutans have not been sighted in parts of the affected area since the cyclone. Indonesia’s deadly floods have been described by scientists as an “extinction-level disturbance” for the species, due to the scale of habitat destruction and the already fragile status of its population.

Scientists on December 12, 2025 warned that the loss of even a single orangutan could be devastating for the species’ survival prospects, the AFP news agency reported.

Satellite imagery analysed by researchers, combined with reports from local residents, indicates that the floods, which claimed nearly 1,000 human lives, may also have had catastrophic consequences for wildlife in the Batang Toru region of northern Sumatra.

Scientists focused on the so-called West Block, the most densely populated of the three known Tapanuli orangutan habitats. Before the disaster, the area was home to an estimated 581 individuals, AFP reported.

Erik Meijaard, a long-time orangutan conservationist, told AFP that between 6 per cent and 11 per cent of the orangutans in the area were likely killed by the floods. He warned that adult mortality above 1 per cent a year could push the species towards extinction, regardless of the size of the remaining population.

The Tapanuli orangutan’s unusually small population and limited habitat range make it especially vulnerable to extreme weather events, scientists say.

Satellite images revealed deep scars across the mountains, with landslides stretching for more than a kilometre and reaching nearly 100 metres in width. Researchers said torrents of mud, trees and water would have swept away everything in their path.

The scale of the destruction has also been underscored by the discovery of the carcass of a Sumatran elephant — another critically endangered species — which was washed away by floods in Aceh, northern Sumatra. Images of the elephant circulated widely on social media.

Sumatra is also home to Sumatran tigers, elephants and rhinos, all of which are critically endangered. However, scientists say orangutans and other primates, including gibbons, are particularly at risk because much of the mountainous forest in Tapanuli district suffered massive landslides during the extreme rainfall triggered by Cyclone Senyar.

David Gaveau, a remote-sensing expert and founder of conservation start-up The Tree Map, told AFP he had never seen destruction on such a scale in more than 20 years of monitoring deforestation in Indonesia using satellite data.

“The devastation means remaining Tapanuli orangutans will be even more vulnerable, with sources of food and shelter now washed away,” he said, adding that more than 9 per cent of the West Block habitat was likely to have been lost.

Panut, a conservation scientist cited in the report, said the affected region was not originally preferred habitat for Tapanuli orangutans but that the animals had been pushed into the area due to development in other parts of their range. Following the landslides, he said, the forests have fallen silent.