1.  Introduction

The Bornean orangutan (Pongo pygmaeus) is a flagship species of Southeast Asia's tropical rainforests and one of the world's most endangered primates. Orangutans are close relatives of humans [1]. Beyond their genetic significance, they play a valuable ecological role, recognized as "rainforest gardeners." However, with the intensification of economic globalization and regional development, the tropical rainforests on which orangutans depend are disappearing at an unprecedented rate. In recent years, Indonesia, Malaysia, and the international community have implemented a number of initiatives to protect orangutans, including establishing nature reserves, promoting sustainable palm oil certification, and improving wildlife protection laws [2]. Despite these efforts, conservation outcomes remain constrained. The rate of habitat destruction continues to exceed that of population recovery, while initiatives in ecotourism and community participation remain limited in scope. Confronted with the twin pressures of ecological preservation and economic development, identifying strategies that ensure both the survival of orangutans and the well-being of local communities has become an urgent priority. This article will analyze the current situation, examine the main causes of habitat loss in Bornean orangutans, evaluate existing conservation measures, and further explore viable sustainable development paths for the future.

2.  The current status of Bornean orangutans

The Bornean orangutan is one of only two remaining species of orangutans in the world, primarily found in Kalimantan, Indonesia, and Sabah and Sarawak, Malaysia. According to Voigt et al., between 1999 and 2015, the global demand for natural resources resulted in the loss of more than 100,000 Bornean orangutans (population decreased by approximately 50%), highlighting the profound impact of deforestation, logging, and plantation expansion on orangutan populations [2]. Currently, there are fewer than 104,000 individuals in the wild, a level below that required for long-term survival. Existing habitats are highly fragmented, with many individuals forced to live in isolated patches surrounded by farmland or plantations, limiting genetic exchange and further increasing the risk of extinction. As "rainforest gardeners," orangutans primarily feed on fruit and can spread the seeds of over a hundred tree species. Some large-seeded plants even rely entirely on them for reproduction, thus playing an irreplaceable role in maintaining the diversity and stability of tropical rainforest ecosystems. However, their reproductive rate is extremely low, with females typically taking seven to nine years to give birth, and their offspring remaining dependent on their mothers for six to eight years. Furthermore, due to continued habitat destruction, individuals often enter farmland due to food shortages, leading to conflicts with humans and even hunting. Furthermore, the illegal pet trade, frequent forest fires, and abnormal weather conditions exacerbate the pressures on their survival.

3.  Major threats to the loss of orangutan habitat in Borneo

3.1.  Deforestation

Deforestation is the primary driver of the loss of orangutan habitat in Borneo. Since the 1970s, Indonesia and Malaysia have vigorously developed logging, turning the original tropical rainforest into a timber export base. In Borneo, about 4.5 million hectares of forest have been cut down, of which 350,000 hectares are forests [3]. Large tracts of original forest have been cut down, and the large areas of original forest on which orangutans depend for survival have been cut down, forcing them to retreat to secondary forests and marginal woodlands [4]. Deforestation has reduced food resources, cut off migration routes between populations, increased the risk of genetic isolation and inbreeding, and more seriously, illegal logging continues, which brings great difficulties to forest protection. Deforestation has destroyed the living environment of orangutans and aggravated the ecological degradation of the entire tropical rainforest.

3.2.  Palm oil plantation expansion

The expansion of the palm oil industry is also a major cause of orangutan habitat fragmentation. Indonesia and Malaysia are the world's largest palm oil producers, and together they supply 87% of the world's palm oil [5]. The rapid expansion of the palm oil plantation industry has become the main threat to the loss of habitat for orangutans in Borneo. Since the 1970s, large-scale agro-industrial enterprises in Indonesia and Malaysia have gradually replaced traditional small-scale farming and slash-and-burn agriculture, and large amounts of original tropical rainforest have been cleared and converted into monoculture oil palm plantations [6]. Plantations are called "green deserts". They only have a single tree species and cannot provide a variety of food and nesting conditions. After their habitat disappears, many orangutans have to go to plantations to find food, but they are driven away or hunted. In other words, orangutans in Borneo have lost their habitat or died due to the expansion of palm oil plantations. This shows that the expansion of the palm oil industry remains a key problem for orangutan protection.

3.3.  Infrastructure construction

Economic development has led to large-scale infrastructure construction in Borneo, including roads, dams, and mining projects. While these projects have boosted economic growth, they have also severely damaged orangutan habitats. Road construction directly cuts through forests, fragmenting habitats and restricting orangutan range. Furthermore, roads facilitate poaching, allowing hunters to more easily penetrate remote forests and increasing the risk of orangutan mortality. Mining development has also caused soil erosion and river pollution, undermining the overall stability of forest ecosystems. In addition, large-scale infrastructure projects—particularly dam construction—have inundated extensive tracts of lowland rainforest, forcing orangutans to migrate and often resulting in significant mortality. While infrastructure development is frequently prioritized as a cornerstone of national economic growth strategies, it is seldom accompanied by comprehensive environmental assessments. This omission exacerbates habitat degradation and creates escalating risks for orangutan populations

3.4.  Climate change and forest fires

Climate change is a long-term factor contributing to the loss of orangutan habitats. Global warming has caused more extreme droughts in Borneo, increasing the risk of forest fires. The blazes in 2015 scorched 2.6 million hectares across the archipelago and produced toxic haze that blanketed neighboring countries Singapore and Malaysia [7]. Fires kill orangutans instantly and damage forest ecosystems for a long time, taking decades to recover. The large amounts of carbon dioxide released by the fires also lead to climate change, which creates a vicious cycle. Climate change can cause changes in the fruiting cycle of fruit trees, which in turn affects food supply. All of this will affect the lives of orangutans. In drought years, the production of some important foods, such as durian and figs, will decrease. As a result, orangutans will have to migrate frequently, and their energy consumption will increase.

4.  Conservation measures and current status assessment

4.1.  International protection

The international community plays a significant role in orangutan conservation. First, the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) lists orangutans in Appendix I, prohibiting all forms of international trade in order to prevent pet smuggling and illegal capture. Second, non-governmental organizations (NGOs) such as the World Wildlife Fund (WWF), Orangutan Foundation International (OFI) and the Orangutan Conservation Project (OCP) have long been carrying out conservation work in Borneo, including habitat improvement, individual rescue and rehabilitation training. OFI's rehabilitation center in Kalimantan has released thousands of orangutans. Third, the Roundtable on Sustainable Palm Oil (RSPO) promotes green certification, requiring companies to reduce forest destruction and increase transparency. The RSPO 2020 report shows that approximately 19% of global palm oil production is certified. Although the proportion is not large, it also puts pressure on the international market [8]. In addition, the European Union and the United Nations Development Programme (UNDP) provide financial and technical support to promote the creation of transnational ecological corridors. International protection mechanisms provide a framework and funding for orangutan conservation, but implementation is affected by industry interests and low certification coverage.

4.2.  Efforts at the national and local levels

The governments of Indonesia and Malaysia have also taken relevant measures to protect orangutans. Indonesia has formulated and issued the "Orangutan Action Plan 2019-2029", which aims to stabilize and restore the population by 2029 [2]; Malaysia has strengthened law enforcement through the "Wildlife Conservation Act" and increased criminal penalties for poaching and trading of wild animals and plants [9]. The two countries have also established a number of national parks and protected areas. Indonesia has the Tanum Putang National Park and Malaysia has the Sepilok Orangutan Rehabilitation Center in Sabah. These protected areas accept orphaned young animals and shoulder the mission of scientific research and public education. Local governments have also used land use planning to reduce forest fragmentation. However, there are still gaps in the implementation of these policies. In some areas, law enforcement is not strict and illegal logging is still rampant. In terms of the overall environment, national and local initiatives have made progress in laws and protected area creation, but enforcement and resource allocation are still insufficient.

4.3.  Community engagement

Community engagement is seen as a complementary force in orangutan conservation. In some areas of Borneo, ecotourism has become an alternative economic source. For example, in the Kinabatangan River Basin in Sabah, Malaysia, local communities rely on orangutan-viewing tours to attract tens of thousands of tourists annually, providing a stable income and reducing the incentive to rely on logging and poaching. Furthermore, some projects provide subsidies and training to encourage farmers to shift to sustainable agriculture, cultivating diverse crops instead of a single palm oil crop, which improves livelihoods and reduces pressure on habitats. Non-governmental organizations collaborate with local schools to promote environmental education and raise awareness of orangutan conservation among the younger generation. However, community-based conservation projects also have limitations. Funding sources are unstable and they rely on the short-term tourism market. Without institutional support, these models are difficult to sustain over the long term. Therefore, community engagement must work in tandem with national policies and international funding to achieve sustainable results.

5.  Future sustainable development pathways

5.1.  Improving land use planning

Reasonable land use planning is key to future orangutan conservation. Indonesia and Malaysia have long lacked scientific coordination in forest development, resulting in the continuous encroachment of core habitats. Scholars believe that prioritizing the identification of High Conservation Value Forests (HCVFs) in spatial planning can reduce encroachment on critical habitats. Indonesia issued a "moratorium on reclamation of primary forests and peatlands" in 2011. While limited in coverage, it prevented some core areas from being converted to farmland. Future land planning should utilize satellite remote sensing and GIS to systematically protect orangutan migratory corridors. Furthermore, efforts should be strengthened to restore degraded land, restore ecological corridors, and reduce population isolation.

5.2.  Promoting a sustainable palm oil industry

The palm oil industry is a key pillar of Borneo's economy, contributing significantly to exports and fiscal revenue while also providing livelihoods for numerous smallholder farmers. However, its long-term, unsustainable expansion has led to widespread deforestation and degradation of tropical rainforests, seriously threatening orangutan habitats and the stability of forest ecosystems. To achieve a balance between industrial development and ecological conservation, it is necessary to promote stricter sustainable palm oil production practices. In the future, the international market will establish constraints on enterprises by increasing the demand for green products and traceability systems. For example, the EU's "Zero Deforestation Supply Chain Regulation" will not allow the import of agricultural products that destroy primary forests, which will also provide market incentives for green palm oil. At the same time, emerging technologies such as blockchain can improve supply chain transparency and traceability, ensuring the legal and compliant origin of products. At the local level, technical training and financial support can help smallholder farmers break free from their reliance on traditional, highly destructive production methods, gradually transitioning to sustainable production models and achieving a win-win situation for both economic development and ecological protection.

5.3.  Strengthen cross-border cooperation

Borneo Island spans Indonesia, Malaysia and Brunei. The protection of orangutans is cross-border. The protection actions of a single country are often restricted by administrative boundaries, while the migration and habitat needs of orangutans cross borders. In recent years, the three countries have cooperated under the framework of the Heart of Borneo Initiative, aiming to protect 220,000 square kilometers of rainforest. However, this initiative still lacks funding and law enforcement [10]. In the future, greater efforts are needed to establish cross-border ecological corridors and to institutionalize cooperation in scientific research, law enforcement, and information sharing. Joint databases could be developed to monitor population dynamics, while coordinated cross-border enforcement measures may help address poaching and illegal trade. Additionally, expanding international funding and technical support for transboundary initiatives would help alleviate resource constraints faced by developing countries. Ultimately, the long-term success of orangutan conservation will rely on the depth and breadth of cross-border collaboration.

6.  Conclusion

This study found that the Bornean orangutan, a flagship species of Southeast Asia's tropical rainforests, plays an irreplaceable ecological role as a "rainforest gardener." However, its population is facing severe declines due to deforestation, palm oil plantation expansion, infrastructure development, climate change, and illegal activities. The analysis suggests that while numerous international initiatives and support from non-governmental organizations and institutions provide a critical framework and resources for Bornean orangutan conservation, their effectiveness is constrained by limited coverage, insufficient law enforcement, and conflicts of interest. At the national and local levels, conservation strategies such as the establishment of protected areas, legal reforms, and community-based ecotourism projects have made progress, but these efforts remain hampered by unstable funding, weak institutional support, and ongoing habitat degradation. This means that while some current measures are helping orangutans, they are insufficient to reverse the decline in populations. Successful conservation requires a holistic approach that integrates ecological conservation with sustainable development and local livelihoods.

However, this study also has some limitations, including the reliance on reports and literature. Future research should incorporate more first-hand ethnographic data from local communities to assess the long-term effectiveness of sustainable palm oil initiatives and land use bans.