Indonesian floods were 'extinction level' for rare orang utans

BANGKOK – Indonesia’s deadly flooding was an “extinction-level disturbance” for the world’s rarest great ape, the tapanuli orang utan, causing catastrophic damage to its habitat and survival prospects, scientists warned on Dec 12.

Only scientifically classified as a species in 2017, tapanulis are incredibly rare, with fewer than 800 left in the wild, confined to a small range in part of Indonesia’s Sumatra.

One dead suspected tapanuli orang utan has already been found in the region, conservationists told AFP.

“The loss of even a single orang utan is a devastating blow to the survival of the species,” said Mr Panut Hadisiswoyo, founder and chairman of the Orangutan Information Centre in Indonesia.

And analysis of satellite imagery combined with knowledge of the tapanuli’s range suggests that

the flooding which killed nearly 1,000 people

in November may also have devastated wildlife in the Batang Toru region.

The scientists focused on the so-called West Block, the most densely populated of three known tapanuli habitats, and home to an estimated 581 tapanulis before the disaster.

There, “we think that between 6 and 11 per cent of orang utans were likely killed”, said Mr Erik Meijaard, a long-time orang utan conservationist.

“Any kind of adult mortality that exceeds 1 per cent, you’re driving the species to extinction, irrespective of how big the population is at the start,” he told AFP.

But tapanulis have such a small population and range to begin with that they are especially vulnerable, he added.

Satellite imagery shows massive gashes in the mountainous landscape, some of which extend for more than 1km and are nearly 100m wide, Mr Meijaard said.

The tide of mud, trees and water toppling down hillsides would have carried away everything in its path, including other wildlife like elephants.

Mr David Gaveau, a remote-sensing expert and founder of conservation start-up The Tree Map, said he was flabbergasted by the before-and-after comparison of the region.

“I have never seen anything like this before during my 20 years of monitoring deforestation in Indonesia with satellites,” he told AFP.

The devastation means the remaining tapanulis will be even more vulnerable, with sources of food and shelter now washed away.

Over 9 per cent of the West Block habitat may have been destroyed, the group of scientists estimated.

In a draft paper shared with AFP and set to be published as a pre-print in coming days, they warned that the flooding represents an “extinction-level disturbance” for tapanulis.

Environmentalists have long campaigned against industrial activity in Batang Toru, particularly a hydroelectric dam and gold mine.

Earlier in December Indonesia’s government said industrial plantations, hydropower and gold mining in the region had “contributed significantly to the pressure on the environment”.

They announced they would suspend operating permits for all projects in the region pending a review.

The government, along with environmentalists, has said deforestation contributed to the scale of the flooding disaster.

A study published on Dec 11 also said climate-change-linked heavier rain and warmer seas that can turbocharge storms played a role.

The orangutan experts are urging an immediate halt to development that will damage remaining tapanuli habitat, and an immediate survey of the region.

They also back the expansion of protected areas and work to restore lowland forests.

Mr Panut said the region had become eerily quiet after the landslides.

“This fragile and sensitive habitat in West Block must be fully protected by halting all habitat-damaging development,” he told AFP. AFP