Deadly Indonesia floods wiped out at least 7 percent percent of rare orangutan population, report says

Environmental groups blame rapid deforestation for the devastating flood damage

A wild orangutan of Sumatra hangs on a tree at the Soraya Research Station in the Leuser Ecosystem Area, Subulussalam, Aceh province, Indonesia Mar 14, 2021. Syifa Yulinnas/Antara Foto via REUTERS/File Photo

Deadly floods and landslides in Indonesia's Sumatra last year have wiped out at least 7 percent of the total population of the critically endangered Tapanuli orangutan, a new report released on Wednesday showed.

The cyclone-induced floods and landslides killed at least 1,200 people and damaged around 300,000 homes, with environmental groups blaming the extent of the damage on the rapid deforestation of Sumatra island.

At least 58 Tapanuli orangutans, which are endemic to an area around north Sumatra's Batang Toru forest, were killed in the floods, the report said, citing a survey of the western block of the forest that is home to a majority of the total population of 800 primates.

The report, a joint study by Brunei-based Borneo Futures, World Weather Attribution and Liverpool John Moores University, did not survey the other parts of the forest, which means the death toll could have been higher.

The findings were derived from analysing satellite images of the damage to the West Block of Batang Toru and historical records of the orangutan population there.

Human-induced climate change has likely increased the intensity and frequency of extreme rainfall around Malacca Strait, putting Tapanuli orangutan's habitat at greater risk, the study said.

Erik Meijaard from Borneo Futures, who was the lead author of the study, said the heavy rain soaked the soil so much that large parts of hillsides in the primary forests collapsed in fast-moving landslides.

"If you get caught as an orangutan... if anything comes down at great speeds, survival chances are going to be very minimal, so it became a real concern," he said.

"This level of loss is substantial for a species with such a small total population. When combined with ongoing pressures such as habitat degradation and human-wildlife conflict, it further increases the urgency of implementing and adequately resourcing a coordinated species action plan," Meijaard added.

Panut Hadisiswoyo, another researcher, urged the Indonesian government to work together with NGOs and researchers to prevent the further decline of orangutan population.

"We can minimise the poaching or hunting and then the number probably can be stabilised," he said, adding that all parties must pay attention to the poor use of land, which also contributes to the declining population.