- Villagers in the Batang Toru forest in northern Sumatra say orangutan sightings in their farms and settlements have increased recently.
- They attribute this to the animals being driven out of their forest habitat by ongoing construction of a hydropower plant and dam.
- The construction activity puts added pressure on the already critically endangered Tapanuli orangutan, which numbers fewer than 800 individuals scattered in populations that could be cut off from each other by the project.
- Villagers say it’s important to preserve the animals, as they’re a key seed disperser for the fruit trees that farmers here depend on.
BATANG TORU, Indonesia — With fewer than 800 individuals remaining in the wild today, the critically endangered Tapanuli orangutan isn’t just the most threatened great ape species in the world — it’s also one of the most elusive.
They’re so rare that even the people living in the Batang Toru forest, in the Tapanuli region of northern Sumatra, have rarely seen one. Scientists say it can take weeks in the field to spot just a single Tapanuli orangutan (Pongo tapanuliensis) here, the apes’ only known habitat. The fact that they dwell high in the trees, seldom descending to the ground, makes it even more difficult to catch sight of the orangutans.
But that’s not the case for 66-year old Bullah Hutasuhut, a farmer in Batang Toru.
He said Tapanuli orangutans have been coming into the villagers’ farms nearly every week now.
“In the past, the orangutans sometimes came [to the farms], but not as frequently as now,” Bullah told Mongabay when we visited his home village of Sitandiang last September.
In Luat Lombang, another village in the Batang Toru forest, it’s the same story: more orangutan sightings than ever before. Muara Siregar, the Luat Lombang village chief, said sightings are especially common when the durian fruit is in season.
Residents of the villages of Dolok Nauli and Hutaimbaru, also in Batang Toru, had never before seen orangutans, but now the animals are appearing increasingly often, according to Julius Siregar, an orangutan conservationist with North Sumatra-based environmental NGO Foundation for Sustainable Ecosystem (YEL).
“They said they only heard about orangutans from their grandparents, but now they’ve been seeing [orangutans] more often near their villages,” he told Mongabay.
Both Bullah and Muara said the growing presence of orangutans became particularly noticeable since the start of construction of a hydropower dam in the Batang Toru forest. The $1.6 billion project, part of the Chinese-backed Road and Belt Initiative, was meant to go into operation in 2022, but has been delayed to 2026 because of pandemic-related delays.
Construction of the power plant is underway, with Indonesian state-owned explosives company PT Dahana blasting out a 12.5-kilometer (7.8-mile) main tunnel and 2.7 km (1.7 mi) of secondary tunnels that will channel water from the Batang Toru River to the turbines. A series of tunnel collapses at the project site has killed 17 workers in the space of less than two years.
“Before the project [started], there were no [orangutan sightings],” Muara said. “We had to travel deep into the forests to see them, and we could only see their nests. [Now] they come to the settlement. How could they [stay in the forest] when there’s heavy equipment there?”
Julius agreed that the frequent sightings of Tapanuli orangutans are likely driven by forest clearance, which pushes the apes out of their habitat and into human settlements and farms.
But he said the hydropower project isn’t the only cause of deforestation in the area; the forest is also being cleared for homes and for pulpwood plantations.
Rudianto Saragih Napitu, the North Sumatra provincial wildlife conservation head, said deforestation by companies has largely stopped in the Batang Toru area, with these same companies now focused on rehabilitating the forests in their concessions. He cited the Batang Toru dam as an example.
According to Rudianto, dam developer PT North Sumatera Hydro Energy (NSHE) has finished its land-clearing activities and is now building infrastructure on the cleared land. At the same time, it’s rehabilitating areas that it no longer needs for the operation of the 510-megawatt power plant, he said.
Conservations have warned that the power plant could devastate the most critical areas of the Batang Toru ecosystem, thus jeopardizing the connectivity between the orangutan populations in the west, east and southeast of the area. This fragmentation would dramatically cut the diversity of the ape’s gene pool, leading to inbreeding, disease, and the eventual extinction of each subpopulation.
The risk of this happening has prompted major lenders, including the World Bank’s International Financial Corporation and the Asian Development Bank, to steer clear of the hydropower project.
Despite calls from conservationists for China to withdraw its support for the project, the State Development & Investment Corporation (SDIC), China’s largest state-owned investment holding company, purchased the dam in 2021.
NSHE, the dam developer, didn’t respond to Mongabay’s requests for comment.
Even though anecdotal evidence suggests a growing presence of Tapanuli orangutans in villages, Rudianto said the number of official reports has actually declined.
Since last September, the provincial wildlife conservation agency has received just a single report of orangutan sighting, he said. But this doesn’t mean there are no more cases of orangutan entering locals’ farms, Rudianto added. In fact, it may be the opposite: orangutan sightings in farms may have become so common that people have gotten used to them and no longer see the apes as a pest, Rudianto said.
This might also indicate growing public awareness of the importance of protecting orangutans, he added.
In the case of the single official report, the conservation agency deployed a team to capture the sighted orangutan and relocate to a part of the forest where it could find food. Relocation is only done when orangutans have been spotted in a human area for more than two weeks running, Rudianto said. He described it as a win-win solution, as leaving the orangutans to frequent the farms could lead to an escalation of conflict between the apes and the villagers.
Farmers like Julius say they’re aware of what they stand to lose if the orangutans are driven out of the area.
“The durian harvest nowadays isn’t as good [as before] because the forest is being cleared,” he said. “Often the locals don’t know that orangutans spread seeds. In the past, durian seeds were spread all over the place, but now it’s difficult [to find durian trees]. If the locals don’t deliberately plant durian trees, they won’t grow [on their own].”
Protecting the orangutans thus means protecting the forest and the villagers’ food security, Julius said.
Bullah, the farmer from Sitandiang, also said he’s aware of the role that the orangutans play in the forest ecosystem.
“After they eat [fruits], orangutans usually leave the seeds on the forest [floor], and these seeds will grow,” he said. “That’s why we can find durian trees deep in the forest there.”
Julius said it’s important for locals to remember their ancestral wisdom in relation to the environment and the orangutans.
“There’s an unwritten local wisdom from our ancestors that teaches people to live in harmony with our surroundings and the environment,” he said. “The awareness of this wisdom should be raised among the young generation so that it doesn’t disappear.”
Bullah said that in the past, people here lived in harmony with the orangutans, viewing the apes as sacred animals that shouldn’t be hunted or killed.
“There’s a belief that whoever hurt the orangutans could get misfortune,” he said.
But now, he said, he’s worried that as the orangutans increasingly seek out food like durian from villagers’ farms, people will become agitated. This could lead to them hunting down the apes, putting even greater pressure on a species already edging toward the brink of extinction.
Correction (03/03/2023): an earlier version of the article cited the wrong name for the head of the North Sumatra provincial wildlife conservation. It has been corrected.
Banner image: A Tapanuli orangutan in the Batang Toru forest, North Sumatra, Indonesia. Image by Matt Senior.
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