FMIPA UI Doctoral Research Maps Conservation Priorities for Sumatran Tigers and Orangutans in Gunung Leuser National Park

Depok, September 23, 2026 — Adhi Nurul Hadi, a doctoral candidate in the Biology Study Program at the Faculty of Mathematics and Natural Sciences, Universitas Indonesia (FMIPA UI), has developed a data-driven model to help identify areas that should be prioritized for the protection of Sumatran Tigers and Sumatran Orangutans in Gunung Leuser National Park (TNGL), Aceh and North Sumatra.

The model combines data on levels of threats to wildlife with habitat conditions. The resulting maps can be used to identify locations requiring more intensive patrols, habitat restoration, protection of wildlife movement corridors, and prevention of human-wildlife conflicts.

The research forms part of Adhi's dissertation, titled Developing Landscape Management Models for Sumatran Tiger and Sumatran Orangutan in Gunung Leuser National Park, which he defended during his doctoral promotion examination at the Prof. G.A. Siwabessy Hall, FMIPA UI, Depok, on Wednesday (September 23, 2026).

Adhi analyzed TNGL monitoring data from 29,192 points across 1 x 1-kilometer areas between 2013 and 2020. The data were used to assess two aspects: the level of pressure faced by wildlife and the extent to which an area remains capable of supporting their survival.

The pressures assessed included forest loss, proximity to roads, poaching, human-wildlife conflict, and other human activities. Meanwhile, habitat conditions were assessed based on habitat quality, food availability, wildlife populations, and patrol activities.

The resulting maps categorize areas within TNGL according to levels of threat and habitat conditions. This approach allows conservation management to be tailored to the specific challenges of each area rather than applying the same approach across the entire landscape.

Reduced Threats Do Not Necessarily Mean Habitat Recovery

One of the key findings of Adhi's research is that declining threats to wildlife do not necessarily mean that their habitat has recovered.

Between 2013 and 2020, conservation conditions in TNGL went through three phases. Conditions were relatively stable in 2013–2015, deteriorated in 2016–2017, and began to improve in 2018–2020.

During the most critical period, in 2016–2017, approximately 40.6 percent of areas serving as Sumatran Tiger habitat and 46.1 percent of Sumatran Orangutan habitat fell into the category requiring critical intervention.

This situation followed the 2015–2016 El Niño event, which contributed to fires, forest loss, and changes in the availability of prey species.

Following this period, the level of threat to tigers declined. The average threat index for Sumatran Tigers decreased by 17.2 percent over the study period, partly in line with increased patrol activities.

However, habitat conditions did not immediately improve. The capacity of areas to support Sumatran Tigers reached its lowest point in 2019.

“Conservation efforts cannot focus solely on whether threats to wildlife have decreased. We also need to assess whether their habitats remain capable of supporting wildlife populations in the long term,” said Adhi.

The finding indicates that conservation success cannot be measured solely by reductions in poaching or other threats. Habitat conditions and the capacity of ecosystems to support wildlife populations must also be taken into account.

An Estimated 2,204 Orangutans Are Outside Protected Areas

Adhi's research also identified another challenge in protecting Sumatran Orangutans.

Based on surveys conducted along 208 orangutan nest-observation transects between 2021 and 2023, the Sumatran Orangutan population was estimated at 11,694 individuals. This represents a decline of approximately 19.5 percent compared with the 2016 estimate, or an average decline of around 1.8 percent per year.

The research indicates that forest cover loss is one of the major factors associated with changes in orangutan population conditions.

Of particular concern, approximately 2,204 individuals, or 18 percent of the Sumatran Orangutan population, are estimated to live in non-forest landscapes without formal protection status.

This finding indicates that orangutan protection cannot rely solely on national parks. Habitats outside protected areas also need to be considered in spatial planning and biodiversity conservation efforts.

Adhi recommends several options, including protecting essential ecosystem areas, incorporating orangutan habitats into social forestry and conservation area management, and expanding conservation partnerships with local communities.

Maps Identify Areas Requiring Priority Action

The model developed by Adhi also identifies areas that should receive priority attention. The highest levels of pressure on Sumatran Tigers and Sumatran Orangutans were found in transition zones between forests and agricultural land, particularly in the eastern and southeastern parts of TNGL.

Therefore, the research recommends increasing patrols in areas that continuously face high levels of threat. Degraded habitats, particularly in lowland areas that serve as wildlife movement corridors, should also be restored.

To reduce human-wildlife conflict, Adhi recommends early warning and rapid response systems in forest-edge areas. By identifying high-risk locations, preventive measures can be implemented before conflicts occur.

“By identifying the areas facing the greatest threats and assessing their habitat conditions, conservation efforts can be directed toward locations that most need intervention,” said Adhi.

The model can help protected-area managers and government authorities determine which locations should be prioritized for patrols, habitat restoration, wildlife movement corridor protection, and conflict prevention.

Conservation Extends Beyond National Park Boundaries

Adhi's research shows that Sumatran Tigers and Sumatran Orangutans experienced relatively similar patterns of change. Both faced their most critical conditions during the same period and began showing signs of recovery afterward.

These findings underscore the importance of landscape-scale conservation management. Wildlife does not recognize administrative boundaries of national parks. They require connected habitats, including areas located outside national parks.

Therefore, wildlife protection requires collaboration among protected-area managers, local governments, communities, and other stakeholders operating around forest areas.

The model developed by Adhi can also serve as a tool for evaluating conservation outcomes. Evaluation should not only examine whether threats to wildlife have declined, but also whether habitats have actually improved and remain capable of supporting wildlife populations over the long term.

This approach can be adapted for other protected areas by adjusting it to the data available in each respective region.

Adhi's dissertation was conducted under the supervision of Promoter Prof. Jatna Supriatna, M.Sc., Ph.D., from the Department of Biology, FMIPA UI, as well as Co-Promoters Prof. Chris R. Margules, Ph.D., from James Cook University, Australia, and Dr. Noviar Andayani, M.Sc., from the Department of Biology, FMIPA UI.

The doctoral promotion examination was chaired by Dean of FMIPA UI Prof. Dr. Tito Latif Indra, M.Si. The research demonstrates how wildlife and habitat monitoring data can be transformed into priority maps to help guide more targeted and effective conservation measures.