- A proposed zoning overhaul in Indonesia’s North Sumatra province could strip legal protections from nearly a third of the Batang Toru ecosystem, threatening the last remaining habitat of the critically endangered Tapanuli orangutan.
- The proposal came just before a powerful cyclone triggered floods and landslides that may have killed or displaced dozens of Tapanuli orangutans and severely damaged thousands of hectares of forest.
- The changes would weaken scrutiny of mining and plantation projects, including a planned expansion of a nearby gold mine, by removing the area’s “provincial strategic” designation.
- Conservationists say rolling back protections now would be a “nail in the coffin” for the species, calling for emergency protections and expanded conservation measures to prevent population collapse.
JAKARTA — Reeling from a cyclone that may have erased a chunk of its population, the Tapanuli orangutan, the world’s rarest great ape population, now faces the prospect of losing more of its already constricted habitat.
Just weeks before a rare tropical storm in the Malacca Strait unleashed torrential rains and mudslides that wiped out part of the Batang Toru forest in Indonesia’s North Sumatra province, local authorities proposed a zoning overhaul that would make it easier to weaken environmental scrutiny for development projects in the region.
At a meeting on Oct. 22 in Medan, the North Sumatra provincial capital, they called for scaling back the area zoned as “strategic” by nearly a third, from 240,985 to 163,402 hectares (595,487 to 403,775 acres).
The “provincial strategic area” designation in the context of natural ecosystems means that zoning in the area must prioritize ecological functions, assess land-use decisions at the landscape scale, and subject applications for activities such as mining and plantations to extra scrutiny.
Removing that designation weakens the legal basis for rejecting projects that pose environmental risks.
Panut Hadisiswoyo, founder of the Orangutan Information Centre (OIC), who attended the Medan meeting, said the plan would devastate the western sector of Batang Toru that’s home to the highest density of Tapanuli orangutans (Pongo tapanuliensis).
“If Batang Toru is excluded, the landscape would lose legal recognition as a critical ecosystem,” he told Mongabay. “The western block — the largest block [of orangutan habitat] — would no longer be part of the ecosystem map. Without that delineation, development there would face no special safeguards.”
Losing a third of orangutan range
An analysis of the proposed zoning changes by U.S.-based campaign group Mighty Earth, at Mongabay’s request, shows they would result in around 39,000 hectares (96,400 acres) of Batang Toru’s western sector losing its “strategic area” zoning designation.
That amounts to nearly a third of the Tapanuli orangutan’s forest range, Mighty Earth pointed out.
Crucially, the changes might benefit the nearby Martabe gold mine, which has been under scrutiny from conservation groups and scientists for the potential impacts of its planned expansion on the orangutans and their habitat.
Under the proposed changes, the area that the mine plans to expand into would no longer be part of the “strategic area,” and thus no longer subject to the heightened environmental safeguards that come with it, according to the analysis.
Mongabay reached out for comment to the mine operator, PT Agincourt Resources, but didn’t receive a response by the time this story was published.
‘Nail in the coffin’ for the species
The proposal is especially alarming given that the western sector bore the brunt of the recent floods and landslides, said Amanda Hurowitz, the forest commodities lead at Mighty Earth.
“If this plan goes ahead, it would be an ecological disaster and likely another nail in the coffin for the Tapanuli orangutan as a species, given that as many as 54 individuals may have been impacted, with a substantial number likely killed by landslides, treefall or flooding in the catastrophic cyclone that hit northern Sumatra,” she told Mongabay.
That figure comes from a new paper, currently in preprint, by a group of 14 scientists and conservationists, including Panut from the Orangutan Information Centre.
By overlaying satellite images of landslide scars with known areas of orangutan occupancy, they concluded that a substantial proportion of the apes in the disaster zone were affected by the disaster, placing them at high risk of death, severe injury or displacement.
They calculated at least 3,964 hectares (9,795 acres) of previously intact forest were severely damaged in the disaster. But because 36% of the area was obscured by cloud cover in the satellite imagery, they extrapolated that the total damage could be nearly double that size, at 6,451 hectares (15,941 acres).
Before the disaster in late November, forest cover within the analyzed area was estimated at 99.2% intact, indicating that the loss was driven not by gradual deforestation but by sudden slope failure and erosion.
The paper stresses that the estimate of up to 54 orangutans impacted is derived from modeling rather than confirmed deaths. If confirmed, however, the authors say the extreme weather event may have pushed the Tapanuli orangutan, with a total population of around 800, closer to population collapse.
The authors called on the Indonesian government to enact emergency protections, halt habitat-damaging development, and expand protected areas to safeguard the species and restore critical forest.
Shrinking ecosystem
Zoning officials confirmed to Mongabay that the Medan meeting discussed shrinking the amount of the Batang Toru ecosystem that falls under the “strategic area” designation.
Edwar Darmansyah Pohan, the provincial government’s head of zoning implementation, said the revised delineation reflects technical recommendations made during a review process at the Ministry of Agrarian and Spatial Planning. The ministry had advised that the delineation “did not need to be too large,” Edwar told Mongabay.
But a top ministry official denied any such discussions. Rahma Julianti, the ministry’s director for zoning for the region that includes North Sumatra province, said there had been no talks on any revisions with the provincial government.
“To date, the North Sumatra provincial government has never conducted a substantive consultation on the spatial plan revision with us, nor has it submitted the revision materials to us,” she told Mongabay. “As a result, we do not yet know whether there is any proposal to change the size of the Batang Toru ecosystem area in question.”
Edwar suggested a key reason for wanting to shrink the size of the “strategic area” was because the provincial government didn’t have the capacity or budget to manage “such a vast area.”
He said the North Sumatra government is also considering asking the central government to take over management and funding for Batang Toru by designating it a national rather than provincial strategic area.
“Given that the disaster has claimed more than 1,000 [human] lives, we support its designation as a national strategic area,” Edwar said. “So we are asking that it be designated as such, so the central government can also give it proper attention and allocate funding from the national budget.”
‘An insane idea’
For now, it remains unclear whether provincial authorities will proceed with the proposed zoning changes following the floods and landslides, which officials have acknowledged were exacerbated by deforestation and poor land management.
The central government recently announced it was moving to suspend industrial operations and review certain logging and plantation permits in Batang Toru in response to the disaster.
That makes this the perfect time for the government to fulfill its promise of protecting and restoring the environment, Mighty Earth’s Hurowitz said.
“Having promised to do more to restore nature in the aftermath of the terrible flooding, this is an opportunity for the government to shelve this proposal and get on with developing a comprehensive plan to protect this ecosystem and the people and animals that live there, to prevent further tragic loss of life,” she said.
“Opening the door to more extractive industries would be an insane idea before the cyclone hit and is even worse one now,” she added.
The authors of the new paper point to what they say is already at stake. Earlier this month, a Tapanuli orangutan was found dead beneath mud and logs in a village in northern Sumatra, suspected to have been swept out of its habitat by the floods and landslides.
“Without immediate intervention,” the authors write, “the Tapanuli orangutan faces the imminent risk of becoming the first great ape species to go extinct in modern history.”
Citation:
Meijaard, E., Wafiy, M., Ni’Mattulah, S., Dennis, R., Hadisiswoyo, P., Sheil, D., … Wich, S. (2025). Extreme rainfall event in Sumatra caused critical habitat loss and lethal impacts to the critically endangered Tapanuli orangutan. Preprints. doi:10.20944/preprints202512.1273.v1
Banner image: A juvenile Tapanuli orangutan was sighted in Lumut Maju peat swamp forest, beyond its known Batang Toru range. Image by Junaidi Hanafiah/Mongabay-Indonesia.
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