Bornean orangutan

The three Bornean orangutan subspecies have experienced dramatic declines in both habitat and numbers. Past events on Borneo demonstrate that even large or seemingly well protected populations cannot be considered safe or without need of strong protection efforts.
 / ©: naturepl.com / Anup Shah / WWF-Canon
© naturepl.com / Anup Shah / WWF-Canon
Close up face portrait of male orang utan (Pongo pygmaeus) rel=
Close up face portrait of male orang utan (Pongo pygmaeus)
© naturepl.com / Edwin Giesbers / WWF

Key facts

  • Common names

    Bornean orangutan; Orangoutan de Borneo(Fr); Orangután de Borneo(Sp)

  • Scientific name

    Pongo pygmaeus

  • Location

    Borneo (Malaysia and Indonesia)

  • Population

    45,000 - 69,000 wild individuals

  • Status

    Endangered

    More

Bornean orang-utan, Sarawak (Borneo), Malaysia. / ©: Michel TERRETTAZ / WWF-Canon
Bornean orang-utan, Sarawak (Borneo), Malaysia.
© Michel TERRETTAZ / WWF-Canon

High-quality habitat is critical

While Bornean orangutans appear tolerate habitat disturbance better than Sumatran orangutans, the species breeds much faster in high-quality habitat.

Social structure
Adult orangutans are generally solitary, although temporary aggregations are occasionally formed. 

Although arboreal, Bornean orangutans (especially adult males) more often descend to the ground than Sumatran orangutans.
 
Life cycle
The age of first reproduction for females is around 10-15 years of age, but there may be differences between the subspecies. The inter-birth interval can be as low as 5 years in high-quality habitats.
 
Diet
About 60% of the orangutan's diet comes from fruit, with the rest comprising young leaves and shoots, insects, soil, tree bark, woody lianas, and occasionally eggs and small vertebrates.

Habitat

Major habitat type
Tropical and Subtropical Moist Broadleaf Forests

Biogeographic realm
Indo-Malayan

Range States
Indonesia, Malaysia

Geographical Location
Borneo

Ecological Region
Borneo Lowland and Montane Forests 

Population & distribution

Previous population & distribution
The Bornean orangutan was once distributed throughout large areas of Kalimantan (Indonesia) and Sarawak and Sabah (Malaysia) on the island of Borneo, but typically at a relatively low abundance.

Three subspecies are recognized, localized to different parts of the island (see map to the right):
  • P. p. pygmaeus
  • P. p. morio
  • P. p. wurmbii (the most common subspecies).

Current population & distribution
Both numbers and distribution have declined rapidly since the middle of the 20th century, due to human activities. These include hunting, unsustainable and often illegal logging, mining, and conversion of forests to agriculture. One particularly catastrophic event was the 1997/ 98 forest fires in Kalimantan, which killed up to 8,000 individuals.

Overall, numbers of Bornean orangutans have declined by more than 50% over the past 60 years, while the species' habitat has been reduced by at least 55% over the the past 20 years.

Most Bornean orangutans are now found in Kalimantan, where extensive areas of forest still exist, especially along the east coast. The majority of  wild populations are located outside of protected areas, in forests that are exploited for timber production or in the process of being converted to agriculture. 

Densities and population sizes are in decline across the species' range, and forest continues to be lost at a rapid rate.
  • The most numerous subspecies, P. p. wurmbii, is primarily found in the large swamp and lowland dipterocarp forest areas of Central Kalimantan, where at least 35,000 individuals survive. Major strongholds include Tanjung Puting, Sebangau and Arut-Belantikan, while an important population is found in Mawas, and a population further west in Gunung Palung. However, while still extensive, this habitat is becoming increasingly fragmented. Elsewhere, other once sizeable populations are disappearing fast.
     
  • P. p. pygmaeus is the most endangered subspecies. Core populations are found in four protected areas in western Borneo: Lanjak Entimau, Batang Ai, Danau Sentarum and Betung Kerihun. Its stronghold, Danau Sentarum, has been seriously affected by logging and hunting, and a mere 1,500 individuals or so remain. Many swamps in the area are small, fragmented and targeted by hunters. 
     
  • The main stronghold of P. p. morio is the Berau/Gunung Gajah population, although remnants in what was once Kutai National Park may be worth protecting. New evidence suggests that P.p. morio has a strong presence in Sabah.
Orangutan distribution on Borneo (Indonesia, Malaysia). The distribution of Orangutan on Borneo is ... / ©: Hugo Ahlenius, UNEP/GRID-Arendal
Orangutan distribution on Borneo over time.
© Hugo Ahlenius, UNEP/GRID-Arendal
Data from: Ancrenaz, M. and Lackman-Ancrenaz, I. 2004. Orangutan status in Sabah: distribution and ... / ©: In: Singleton, I., S. Wich, S. Husson, S. Stephens, S. Utami Atmoko, M. Leighton, N. Rosen, K. Traylor-Holzer, R. Lacy and O. Byers (eds.). 2004. Orangutan Population and Habitat Viability Assessment: Final Report. IUCN/SSC Conservation Breeding Specialist Group.
Data from: Ancrenaz, M. and Lackman-Ancrenaz, I. 2004. Orangutan status in Sabah: distribution and population size; Meijaard, E. and Dennis, R. 2003. Assessment of the extent of remaining habitat for Bornean Orangutan, based on 2002 forest cover data.
© In: Singleton, I., S. Wich, S. Husson, S. Stephens, S. Utami Atmoko, M. Leighton, N. Rosen, K. Traylor-Holzer, R. Lacy and O. Byers (eds.). 2004. Orangutan Population and Habitat Viability Assessment: Final Report. IUCN/SSC Conservation Breeding Specialist Group.

What are the main threats?

Habitat loss and degradation
While Bornean orangutans appear to survive in logged habitat at lower densities – and while some such populations remain surprisingly substantial – habitat loss nevertheless continues to threaten the species.

Massive land conversion projects such as the disastrous Mega-Rice Project in Kalimantan demonstrate how rapidly areas of orangutan habitat can be destroyed. One million hectares of peat-swamp forest was partly cleared and drained during 1995-97 for conversion to rice fields, despite the inadequacy of the land for agriculture.
Habitat disappearing even in protected areas
The boundaries of protected areas in Borneo are often not clearly delineated, which makes them difficult to patrol. Furthermore, many parks are understaffed and underfunded. Consequently, shifting cultivators, oil palm companies and logging concessions have encroached into all the parks. 

Illegal logging has been controlled to some extent in Tanjung Puting and Gunung Palung National Parks. However, illegal logging and other damaging human activities occur in the four protected areas housing P.p. pygmaeus, the most endangered subspecies. 

Collateral damage
Collateral problems associated with habitat loss include the spread of fire, hunting and human-animal conflict.

For example, the drainage of peat-swamp forest mentioned above contributed to uncontrollable fires in Kalimantan in 1997/98, which lasted for 6 months. Due to clearing of vast tracts of the surrounding forests, almost no forest remained for orangutans to seek refuge in, and land changes prevented them from escaping. It is thought that up to 8,000 individuals could have perished in the fires.

Hunting
Orangutans are hunted for food in some areas. Hunting intensity seems to vary from one region to another, a phenomenon probably explained by cultural and religious differences. However, even the slightest hunting pressures can cause a steep decline in numbers, even in good quality habitat. 

Hunting is the likely cause of the very low estimated densities of orangutans in low-hill forests, particularly in the upper reaches of the Katingan and Barito rivers in Central Kalimantan and Pawan river in West Kalimantan. 

Conflict with humans
The animals are also sometimes shot in retaliation when they move into agricultural areas, such as oil palm plantations, and destroy crops. This occurs particularly in times of hardship when orangutans can’t find the food they need in the forest.

Pet trade
Young orangutans are in demand for a flourishing pet trade, with each animal fetching several hundred dollars in city markets in nearby islands such as Java.

Studies have indicated that 200-500 orangutans from Indonesian Borneo alone enter the pet trade each year. In order to obtain live young orangutans, poachers must at least kill the mother, so this trade represents a real threat to wild orangutan populations.

There is also trade in dead orangutan parts in Kalimantan, with orangutan skulls fetching up to US$70 in towns.
 / ©: WWF-Canon / Alain Compost
As many as 8,000 Bornean orangutans perished during forest fires in 1997-98.
© WWF-Canon / Alain Compost
A poacher proudly shows an orang-utan baby (Pongo pygmaeus) that he has caught. Central ... / ©: Alain Compost / WWF-Canon
A poacher proudly shows an orangutan baby (Pongo pygmaeus) that he has caught, Central Kalimantan, Indonesia. A baby orangutan can fetch up to $30,000 USD when sold as a pet on the illegal wildlife trade market.
© Alain Compost / WWF-Canon

What is WWF doing?

Commitment to conserve the Heart of Borneo
In 2007, WWF helped secure a historic declaration that commits the governments of the three countries sharing Borneo – Brunei, Indonesia and Malaysia – to a common vision for the conservation and sustainable development of the 22 million hectares of the forest in an area known as the Heart of Borneo

About one-third of the orangutan habitat on Borneo falls within this central forested area. 

Work to save orangutans
Our strategy to save Borneo’s orangutans forms part of our overall work in the Heart of Borneo, and builds on more than 40 years of WWF’s work on the island. WWF-Indonesia is a also prominent contributor to Indonesia’s National Orangutan Conservation Plan.

We are working in collaboration with central and local government, international research experts, local communities and companies to:
  • Carry out research on orangutan ecology and behaviour. We established an orangutan research station in Sebangu National Park, Kalimantan, which is also looking at the impacts of climate change on the species. Several other stations are under construction or planned, including in a logging concession.
     
  • Create a network of conneted protected areas.  We have orangutan projects in several Indonesian national parks, including Sebangau, Danau Sentarum and Betung Kerihun National Parks, as well as the forest corridor connecting the latter two. We also support a collaborative programme with OPF (Orangutan Protection Foundation) Foundation on reintroduction of orangutan in the northern parts of Central Kalimantanan.
     
  • Ensuring sustainably managed forest and plantation land. WWF has developed scientifically rigorous assessment tools and plans to manage identified orangutan landscapes. We engage with timber and palm oil companies to use these to develop specific protection and management plans for their concessions, in order to mitigate negative impacts on habitats and orangutan populations. For example, studies show that Bornean orangutans can fare well in logged forests if the impact of logging is reduced through measures such as selective logging, keeping fruit trees intact, and controlling hunting.
     
  • Addressing the illegal killing and trade of orangutans. We work with TRAFFIC (the wildlife trade monitoring network) to help governments enforce restrictions on the trade in live animals and orangutan products. We also help to rescue orangutans from traders. Many are taken to refuges where they can recover and be rehabilitated, and are eventually released back into the wild.
     
  • Reducing human-orangutan conflicts. We work with governments, communities and plantation owners on practical methods to keep orangutans out of plantations as well as regional land use planning to ensure that agricultural areas are developed as far away from orangutan habitat as possible.
     
» More on WWF's work in Borneo

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Did you know?

    • An estimated 300 million trees have been cut in Borneo since 1994
       
    • Orangutans have an extremely low reproductive rate, due to the long time taken to reach sexual maturity, the long interbirth periods, and single young. This makes orangutan populations highly vulnerable to excessive mortality, and means they take a long time to recover from population declines.

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