Orang utan ‘extinction level’ event

Ravaged land: A view of the Batang Toru area of South Tapanuli in Sumatra, where a population of the critically-endangered Tapanuli orang utan are known to live, on Oct 28 (top) and on Dec 3 in the aftermath of massive flooding and landslides.— Planet Labs PBC/AFP

The nation’s deadly flooding was an “extinction-level disturbance” for the world’s rarest great ape, the tapanuli orang utan that cau­sed catastrophic damage to its habitat and survival prospects, scientists warned.

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 said.

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

An analysis of satellite imagery combined with knowledge of the tapanuli’s range suggests that floo­ding last month, which killed nearly 1,000 people, may have also 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 six and 11% of orang utans were likely killed,” said Erik Meijaard, a longtime orang utan conservatio­nist.

“Any kind of adult mortality that exceeds 1%, you’re driving the species to extinction, irrespective of how big the population is at the start,” he said on Friday.

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 a kilometre and are nearly 100m wide, 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.

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 said.

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

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

In a draft paper set to be publi­shed as a pre-print in coming days, they warned 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.

The highland homes currently inhabited by tapanulis are not their preferred habitat, but it is where remaining orang utans have been pushed by development elsewhere.

Earlier this month, 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. — AFP