Scientists warn Sumatra deluge may have wiped out up to 10% of remaining Tapanuli population in days
Catastrophic flooding in Indonesia's North Sumatra province has dealt a severe blow to the world's rarest great ape, with scientists warning that the event may have pushed the critically endangered Tapanuli orangutan closer to extinction.
Researchers estimate that between 33 and 54 Tapanuli orangutans (Pongo tapanuliensis) were killed in floods and landslides triggered by intense rainfall in late November. Fewer than 800 individuals were believed to exist in the wild before the disaster, all confined to a single forest landscape in the Batang Toru region.
Experts told The Guardian that the event has caused an "extinction-level disturbance", citing both the scale of habitat destruction and the species' extremely low reproductive rate.
The Tapanuli orangutan was only identified as a distinct species in 2017 and is already under pressure from mining, palm oil plantations and a large hydropower project. Unlike other orangutan species, its entire population is restricted to a limited mountainous area, leaving it highly vulnerable to sudden environmental shocks.
"It's a total disaster," said biological anthropologist Erik Meijaard, one of the scientists who first described the species. "The path to extinction is now a lot steeper."
Preliminary findings by Meijaard and his colleagues, to be published this week, estimate that the floods and landslides wiped out 6.2 per cent to 10.5 per cent of the total population in just a few days -- a demographic shock with few modern parallels among great apes.
According to satellite analysis conducted after the floods: