New Species of orangutan threatened from moment of its discovery

The trifecta

While the genetics research suggested the Tapanuli orangutans were distinct, it wasn’t until a skeleton became available (from a male orangutan named Raya who was shot by residents in 2013 and died in the care of the SOCP eight days later) and showed significant morphological differences that the scientists considered proposing it as a new species.

“That was the smoking gun we were waiting for,” Krützen says. “Describing a new species is like going to court, with no predetermined list of what’s needed.” But taking the genetic, morphological and vocal evidence together, “this was the gold standard.”

On Nov. 2, 2017, the entire team announced their discovery in an article, titled “Morphometric, Behavioral and Genomic Evidence for a New Orangutan Species.” The 37 co-authors outlined the genetic, morphological and vocal evidence that justified their finding.

“It was a massive collaborative effort,” Krützen says.

Threats to this already critically endangered ape

From the moment news broke about the Tapanuli orangutan, it was under threat.

Of most immediate concern is a planned 510-megawatt hydroelectric dam by the Indonesian firm PT North Sumatra Hydro Energy (NSHE). This $1.6 billion project, financed by the Bank of China and built by the Chinese state-owned company Sinohydro, will occupy about 650 hectares (2.5 square miles) of land along the Batang Toru River in South Tapanuli district. The project involves a reservoir, spillway, quarry, camp, road access and other facilities, such as tunnels, power station and transmission lines.

Conservationists say infrastructure like roads and tunnels will cut through rugged primary forest that contains the highest population densities of Tapanuli orangutans.

“This is one of the last remaining bits of lower elevation landscape left,” says Nowak. “There is a reason why orangutan densities are high in this area.

“Usually as you go up in elevation, preferred orangutan food resources start to dwindle and populations can’t be maintained at high densities. As such, orangutans prefer low elevations,” he says. “Most of the Batang Toru ecosystem is at more than 800 meters [2,625 feet] above sea level (i.e. submontane forest). While the species is able to exist in these areas, having the ability to move between upland and lowland areas is critical for a healthy orangutan population.”

NSHE spokesman Firman Taufick disputes concerns about the impact of the project on the orangutans. “The project area is not the primary habitat of orangutan,” he says, citing studies carried out in 2017 and 2018 by the Aek Nauli environmental research center and the North Sumatra provincial administration’s conservation agency.

Taufick also says the tunnel carrying water from the turbine back to the river is designed to be 50 to 200 meters (165 to 655 feet) underground. “Therefore,” he says, “there is no land clearing above the tunnel to avoid the habitat fragmentation.” He also says the inspection road is built parallel to the Batang Toru River, which is already a natural divide between the western and eastern habitats. “This design is made to avoid new fragmentation,” he says. “Therefore, there is neither tunnel nor inspection road that cleaves the primary forest.” He also says the road provides only “limited access directly to the project site” and that the company has adopted “a zero-tolerance policy” toward illegal logging and the ownership and hunting of animals.

Taufick says NSHE has adopted the International Finance Corporation’s (IFC) standards for biodiversity.

However, the IFC standards leave considerable room for flexibility. They state that impacts on biodiversity and ecosystem services should be avoided, but that when that is not possible, mitigation measures should be put in place. The standards also make allowances for mitigation that doesn’t work, suggesting that measures should change in response to changing conditions and monitoring.

Many scientists and conservationists suggest these measures are inadequate to address the significant negative and permanent impact of this project on the orangutan’s habitat.

In June 2018, a team from James Cook University and the University of Indonesia published a study in Current Biology that estimated that the impact of the hydropower project would stretch far beyond its reservoir and alter about 8 percent of the Tapanuli orangutan’s remaining range.

Ian Singleton, director of the Sumatran Orangutan Conservation Programme, says that while the developers claim the dam is small, “the infrastructure is massive and it will have an irreversible impact on these orangutans.”

He says the construction will further open the forest and increase opportunities for people to settle in the area, clear more land, and hunt. That, in turn, will increase the likelihood of conflicts between people and orangutans — a situation, he says, that rarely ends well for the orangutans, like Raya.

Fredriksson, the SOCP’s Tapanuli coordinator, agrees that the consequences are serious. There are so few Tapanuli orangutans that “this species can’t afford even an offtake of a few individuals.”

Orangutans breed very slowly. Sumatran orangutans have the longest interval between births of any mammal. Females give birth for the first time when they’re about 15 years old and then reproduce again only every eight to nine years. Given their 50- to 60-year life span, that means they will have just four to five infants in their lifetime.

Even more problematic, conservationists say, is that the hydropower development threatens to further fragment the already dissected forests where the Tapanuli orangutans live. The species is split into three subpopulations: one of less than 600, another of about 150, and a third of several dozen. In chopping up their already limited habitat, it will impede the orangutans’ ability to move between various forest blocks and also permanently sever their ability to interact. Conservationists fear that will doom the smaller two groups, as they would not be able to maintain safe levels of genetic diversity. To be sustainable over the long term, scientists suggest 500 or more individuals are needed in a population.

“If we can’t connect the two smaller groups to the larger one, they will disappear,” Singleton says. “They’re just not big enough.”