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Study: Indonesia’s new capital city threatens stable proboscis monkey population

  • A recent study warns that the ongoing construction of Indonesia’s new capital city on the island of Borneo could destabilize the population of endangered proboscis monkeys currently thriving in the area.
  • President Joko Widodo has characterized the development as green and with a minimal environmental impact, but concerns have arisen over the potential threat to the nearby Balikpapan Bay mangrove ecosystem that’s home to proboscis monkeys and other threatened wildlife.
  • Scientists have advocated for sustainable development practices and emphasized the importance of respecting local biodiversity while constructing the new city, Nusantara.
  • Their recommendations include legal protection for affected areas, habitat restoration, and collaboration with local stakeholders to mitigate the environmental impact.

JAKARTA — The construction of Indonesia’s new capital city on the island of Borneo may destabilize the current stable population of endangered proboscis monkeys, a study has warned.

President Joko Widodo in 2019 declared the establishment of an entirely new capital in East Kalimantan province, moving the seat of government away from the overcrowded and rapidly sinking Jakarta in an effort to spur economic growth beyond the island of Java. But scientists from Indonesia and Czechia say in their recently published study that the development likely threatens the key mangrove ecosystem of Balikpapan Bay where a population of the proboscis monkeys (Nasalis larvatus) lives.

“The Indonesian government should abide by its public commitments to sustainable development principles and embrace the global importance of this endangered primate and develop Nusantara city with respect for local biodiversity,” they wrote in the paper published in January in the journal Environmental Monitoring and Assessment.

Balikpapan Bay is home to dense native mangroves where threatened species like proboscis monkeys live. Image by Basten Gokkon/Mongabay.

The group of scientists, led by Tri Atmoko, a senior researcher at Indonesia’s National Research and Innovation Agency (BRIN), conducted a population census in known habitats of the proboscis monkey to determine the total current population at 3,907 individuals — all living within the development range of the new city, Nusantara.

In particular, they estimated 1,449 of the monkeys occur within the core area of Nusantara and would be pushed to the edges of their habitat by the ongoing construction work.

“The current scheme of the Nusantara city construction presents a new threat to the proboscis monkey population, but it also provides new unique opportunities to strengthen ongoing conservation efforts,” they wrote.

While a part of Balikpapan Bay is censused every five years, this study is the first full census conducted of the species. Three previous censuses of the proboscis population within the Balikpapan city administrative area showed a stable population size over a period of 10 years. A 2020 study by some of the same authors even found that the rate of habitat loss had slowed since 2000 and predicted it should stop and reverse in 2036 if nothing changes dramatically, thanks to the decline in large-scale agriculture plantations and also efforts by local conservationists and concerned citizens.

Traditional small fishers in Balikpapan and neighboring North Penajam Paser district rely on the sustainability of Balikpapan Bay and its resourceful ecosystem. Image by Basten Gokkon/Mongabay.

Balikpapan Bay is home to large expanses of mangroves that host a rich diversity of marine and terrestrial life. Coral reefs and seagrass meadows are believed to grow underwater, and traditional fishers have relied on the bay for their livelihoods since the 1970s.

The bay sits less than 100 kilometers (60 miles) from where the Mahakam River, the third-longest in Borneo, empties out into the Makassar Strait. The Mahakam is the core habitat of another threatened species, the critically endangered Irrawaddy dolphin (Orcaella brevirostris), with the mammals often also spotted in Balikpapan Bay. But decades of urban and industrial development along the coast, and disastrous spills polluting the waters have degraded the bay’s ecosystem.

The authors suggested key measures to reduce the impacts of the Nusantara city development on proboscis monkeys and habitats in Balikpapan Bay, including the establishment of legal protection status of the impacted areas, the enforcement of wildlife protection that extends beyond the limits of the new capital, and the prevention of illegal land speculation that often drives deforestation.

They also called for maintaining habitat connectivity, keeping and creating buffer zones of terrestrial forest along the mangrove swamp, developing upstream water reservoirs to provide drinking water for locals, and conducting reforestation and habitat restoration, especially in areas that contain key food resources.

The Indonesian government has promised that the construction of Nusantara, slated for completion in 2045 and estimated to cost $33 billion sprawling across 256,000 hectares (632,600 acres) of land split into core government and urban zones, would be a “green forest city” with a construction strategy that poses minimal environmental damage and a development design that aims at net-zero carbon emissions.

An Irrawaddy dolphin in Balikpapan Bay. Image courtesy of Rare Aquatic Species of Indonesia (RASI) Foundation.

Mongabay shared the study for review with Myrna Asnawati Safitri, the deputy for environment and natural resources at the OIKN, the government agency overseeing Nusantara’s development, and asked her for her comments on the findings and recommendations.

“I have checked and got information that some of the initial findings of this research have been used in the survey report by our team of consultants, which has now become materials included in the biodiversity master plan document by the OIKN,” Myrna told Mongabay in a text message, adding that the master plan is scheduled to be released in March.

She said her office has taken some mitigation measures to protect the Balikpapan Bay ecosystem, including designating the mangrove ecosystem as a protected area, allocating a small island as a wildlife reserve, and conducting mangrove rehabilitation. She added that her team had reached out to local NGOs and civil society groups for their involvement in monitoring and management.

While most of the recommendations in the latest paper have been taken into account, Myrna said, the development of upstream water reservoirs needs to be further explored. Another recommendation not yet considered is the expansion of the protected zone outside the Nusantara city limits, as this would have to be discussed with neighboring jurisdictions.

“We initiated the discussion last year and it must be intensified,” Myrna said. “We hope for the understanding that the OIKN, especially going forward, is still very limited in resources. But, the importance of coordination and discussion across regions is part of our agenda.”

The Point Zero landmark with trees.
The Zero Point landmark sits at the heart of Nusantara, Indonesia’s new capital city. Image by Basten Gokkon/Mongabay.

Basten Gokkon is a senior staff writer for Indonesia at Mongabay. Find him on 𝕏 @bgokkon.

See more from this reporter:

Mangroves and wildlife in Bornean bay at risk from Indonesia’s new capital


Atmoko, T., Toulec, T., Lhota, S., & Darman. (2024). Population status of proboscis monkeys in Balikpapan Bay and their potential survival challenges in Nusantara, the proposed new capital city of Indonesia. Environmental Monitoring and Assessment, 196. doi:10.1007/s10661-023-12252-z

Toulec, T., Lhota, S., Soumarová, H., Putera, A. K., & Kustiawan, W. (2020). Shrimp farms, fire or palm oil? Changing causes of proboscis monkey habitat loss. Global Ecology and Conservation21, e00863. doi:10.1016/j.gecco.2019.e00863

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