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we co-authored in Nature Ecology & Evolution (NEE), we reiterated to the Indonesian government to halt the Batang Toru dam development so that an independent and objective assessment can be conducted of the risks for the Tapanuli orangutan associated with hydro dam development in its habitat. In a surprising turn of events, the halting part of our wishes was fulfilled, although for the wrong reasons – COVID 19. The power plant developer recently requested , because its Chinese workers cannot currently travel to Indonesia. Does this postponement provide an opportunity to seriously discuss how we can avoid the extinction of the rarest great ape on Earth with the Indonesian government, and together develop a well-funded conservation strategy for the species?

For those unfamiliar with the Batang Toru context, this is once again a story of biodiversity threats under an expanding human footprint. It is playing out in Indonesia, a megadiverse nation with many threatened species, where the survival of the Tapanuli orangutan is hanging by a thread.

A proposed $1.6 billion hydro-electric power structure would cut across the Tapanuli orangutan’s largest subpopulation and effectively act as a wall blocking connectivity between the already fragmented forest areas.Ìý

The main risk to the species at the moment appears to be the pending development of Indonesia’s largest hydropower project in the middle of its range. The Section on Great Apes of Ïã¸ÛÁùºÏ²Ê¿ª½±½á¹ûÏÖ³¡Ö±²¥â€™s Primate Specialist Group (Ïã¸ÛÁùºÏ²Ê¿ª½±½á¹ûÏÖ³¡Ö±²¥ SGA), of which we are part, has been leading efforts to convince the Indonesian government to review plans for a hydro-electric project that would separate the three subpopulations of the Tapanuli orangutan and further undermine their survival. Importantly, the Ïã¸ÛÁùºÏ²Ê¿ª½±½á¹ûÏÖ³¡Ö±²¥ÌýSGA’s suggestions align with the Indonesian Government’s with Ïã¸ÛÁùºÏ²Ê¿ª½±½á¹ûÏÖ³¡Ö±²¥ of the impact of the project, which states it should be halted. So, what’s the issue?

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The was discovered scientifically as recently as 1997 and occurs in an area of northern Sumatra known as Batang Toru in which it survives in a rainforest area that covers less than 1,200 km2. Its estimated numbers are as low as ca. , divided among three subpopulations.ÌýThe area that it occurs in is a based on the Global Standard for the Identification of Key Biodiversity Areas (Ïã¸ÛÁùºÏ²Ê¿ª½±½á¹ûÏÖ³¡Ö±²¥ 2016) and is mostly protected, but a part of it that is crucial for its connectivity is not, and worryingly,Ìýpart of this is being developed for hydro-electric power.ÌýThe species has much declined in historic times and any further population losses would rapidly drive the Tapanuli orangutan to extinction. If the population loses more than 1% of adult animals per year, it will go extinct in the foreseeable future. Given the recent rescues of or Tapanuli orangutans it is clear that losses are high. Indonesia’s conservation laws are meant to prevent this.

The project is a $1.6 billion hydro-electric power infrastructure scheme which would cut across the Tapanuli orangutan’s largest subpopulation, and effectively act as a wall blocking connectivity between the already fragmented forest areas. The company developing the project is the Jakarta-based North Sumatera Hydro Energy, but much of the actual construction work is conducted by China’s national hydropower agency, Sinohydro,Ìýwhich is the largest dam-builder in the world.Ìý

The most endangered great ape species in the world deserves the highest level of protection.

In the NEE paper we argue that this hydro-electric project would not be developed in most nations due to environmental concerns about its impacts. These concerns have made international funders increasingly cautious about financing the project. The International Finance Corporation (IFC) concluded that the potential environmental impacts of the project were too high. An IFC-funded environmental assessment found that Tapanuli orangutan densities were 26-57% higher in forests in the hydro project’s footprint than elsewhere in its range. The same assessment confirmed that the project’s infrastructure would cut through the only area of intact forest that still links the ape’s three subpopulations. Two other major funding bodies, the Bank of China and the Asian Development Bank have informally declined to fund the project for similar environmental reasons.ÌýWith access to international funding increasingly difficult, the proponents of the Batang Toru project are using misleading arguments to support their case, .

Despite reservations in many quarters, the hydro scheme at Batang Toru is continuing, but a break in construction because of the COVID-19 pandemic provides an opportunity to critically re-examine the project and its rationale. The potential three-year delay recently announced by the project developer provides a chance for the Indonesian government to re-examine the objectives and risks of the project and to see whether there is an opportunity to achieve national sustainability objectives in a different way. The Indonesian Ministry of Environment and Forestry and its conservation department have the obvious authority and legal obligation to ensure that the dam infrastructure will not harm the species. The fact that the Ministry’s own call to halt the dam is not heeded indicates that more powerful forces in the government are overruling the country’s environmental law.

A break in construction because of the COVID-19 pandemic provides an opportunity to critically re-examine the project and its rationale.

As requested by Ïã¸ÛÁùºÏ²Ê¿ª½±½á¹ûÏÖ³¡Ö±²¥, and to assist the Indonesian government authorities in its decision-making, it is important to carry out objective and independent studies regarding the risks for the Tapanuli orangutan. No robust studies have yet assessed the importance of the project site for retaining connectivity among the three subpopulations of the orangutan, nor how habitat loss and the infrastructure from the project would affect orangutans in that area. To resolve scientific uncertainties, we recommend (1) genetic studies to determine the level of past and potential dispersal frequency and related gene flow across the Batang Toru River, and how this would be affected by dam infrastructure; (2) genetic studies to determine recent population trends and whether the Tapanuli orangutan had until recently a much larger range; (3) improving estimates of the number of orangutans in all three subpopulations; and (4) quantifying the various threats to orangutans such as habitat loss and killing.Ìý

Cancelling the hydropower plans and moving the project, or an alternative option to generate energy, to another, lower-risk location, would show the world that Indonesia takes its international sustainability commitments and national environmental legislation seriously.

The current delays might be an opportunity for the Indonesian government to propose alternative plans for the Batang Toru area – a life after the dam. The most threatened great ape species in the world deserves the highest level of protection. Cancelling the hydropower plans and moving the project, or an alternative option to generate energy, to another, lower-risk location, would show the world that Indonesia takes its international sustainability commitments and national environmental legislation seriously. Incorporating the whole non-protected area of which the project area is part into the protected forests of Batang Toru would add further security to the region’s wildlife and vital environmental services. We stand ready to work with the government to find and support implementation of a long-term conservation solution for the Tapanuli orangutan.

We call on all Ïã¸ÛÁùºÏ²Ê¿ª½±½á¹ûÏÖ³¡Ö±²¥ members to push for solid peer-reviewed scientific reviews for projects with potentially large environmental impacts and to utilise the broad global expertise available within Ïã¸ÛÁùºÏ²Ê¿ª½±½á¹ûÏÖ³¡Ö±²¥ to do such research. Where this concerns negative impacts from energy, extractive and associated infrastructure projects on apes, we encourage you to work with the new Ïã¸ÛÁùºÏ²Ê¿ª½±½á¹ûÏÖ³¡Ö±²¥ SSC Primate Specialist Group .