/ ©: naturepl.com / Anup Shah / WWF

Orang-utans

Orang-utans are the world's largest tree-climbing mammals. But their forest habitat in Indonesia and Malaysia is rapidly disappearing, putting the future of Asia's only great ape in peril.

Subscribe to WWF

 rel=
Sumatran orangutan (Pongo abelii) female swinging through the trees with male baby. Gunung Leuser National Park, Sumatra, Indonesia.
© naturepl.com/Anup Shah / WWF

Why orang-utans matter

Orang-utans are known as gardeners of the forest. They play a vital role in seed dispersal and in maintaining the health of the forest ecosystem, which is important for people and a host of other animals, including tigers, Asian elephants and Sumatran rhinos. So by conserving the orangutan’s habitat, we’re also benefiting local communities and other species.

Physical description 

Orang-utans have a characteristic ape-like shape, shaggy reddish fur and grasping hands and feet. Their powerful arms are stronger and longer than their legs and can reach 2m in length, long enough to touch their ankles when they stand.

There are two different types of adult male orang-utan: flanged and unflanged. Flanged males have prominent cheek pads called flanges and a throat sac used to make loud verbalizations called 'long calls'. They also have a long coat of dark hair on their back.

The unflanged male looks like an adult female. Both reproduce and an unflanged male can change to a flanged male for reasons that are not yet fully understood. Orang-utans are the only primate in which this biological phenomenon occurs.

Male orang-utans can tip the scales at 90 kg, while females weigh between 30-50 kg.

Social structure
Orang-utan means 'person of the forest' in the Malay language. They live in primary and secondary forests. Although they can occur up to 1,500m above sea level, most are found in lowland areas and prefer forests in river valleys or floodplains.

Orang-utans travel by moving from one tree to another, and usually avoid climbing down to the ground. But when they do, they move on 'all fours', placing their clenched fists on the ground.

Orang-utans make a nest of vegetation to sleep in at night, and rest in smaller nets during the day.

Adults are generally solitary, although temporary aggregations are occasionally formed. Males' large home ranges overlap with the ranges of several adult females. Adult males are generally hostile to one another, although they do not display territorially.

Life cycle
Orang-utans can live up to 50 years in the wild. Females first reproduce between 10-15 years of age. They give birth at most once every 5 years, and the interval between babies can be as long as 10 years.

Orang-utans usually give birth to a single young, or occasionally twins. Orang-utans stay with their mothers for the first 7-11 years of their life. An infant rides on its mother's body and sleeps in her nest until it is able to survive on its own.

The long time taken to reach sexual maturity, the long interbirth periods, and the fact that orang-utans normally give birth to just a single young mean that orang-utans have an extremely low reproductive rate.

This makes orang-utan populations highly vulnerable to excessive mortality, and means that populations take a long time to recover from population declines.

About 60% of the orang-utan's diet includes fruit, such as durians, jackfruit, lychees, mangosteens, mangoes and figs. The rest comprises young leaves and shoots, insects, soil, tree bark, woody lianas, and occasionally eggs and small vertebrates. They obtain water not only from fruit, but also from tree holes.
 

Two species

There are two species of orang-utan - the Bornean and Sumatran - which differ a little in appearance and behavior. While both species have shaggy reddish fur, Sumatran orangutans have longer facial hair.

Sumatran orang-utans are also reported to have closer social bonds than their Bornean cousins.

The Sumatran orang-utan is almost exclusively arboreal. Females virtually never travel on the ground and adult males do so only rarely. This is in contrast to Bornean orang-utans, especially adult males, which more often descend to the ground.
Male Bornean Orang-utan (Pongo pygmaeus) / ©: David Lawson / WWF-UK
Flanged male Bornean orangutan (Pongo pygmaeus)
© David Lawson / WWF-UK
Tree emerging from tropical rainforest. Gunung Leuser National Park, Sumatra, Indonesia.  / ©: Alain Compost / WWF
Tree emerging from tropical rainforest. Gunung Leuser National Park, Sumatra, Indonesia.
© Alain Compost / WWF
 / ©: WWF
© WWF
 / ©: WWF
Orangutan
© WWF
 / ©: naturepl.com / Anup Shah / WWF
© naturepl.com / Anup Shah / WWF

Key facts

  • Species

    Sumatran orang-utan (Pongo abelii), Bornean orang-utan (Pongo pygmaeus)

  • Common names

    Orangoutan de Sumatra/Borneo (Fr); Orangután de Sumatra/Borneo (Sp)

  • Location

    Sumatra (Indonesia), Borneo (Malaysia and Indonesia)

  • Status

    Endangered (Bornean - 54,000) and Critically Endangered (Sumatran - 6,600)

  • Meaning of name

    Orang-utan means 'man of the forest' in Malay language

Population & distribution

Orang-utans were once distributed widely across Southeast Asia, roaming as far north as southern China, and as far south as the Indonesian island of Javar. But today Asia's great ape is confined to just two islands, Borneo and Sumatra.

As the orang-utan's range has decreased so have its numbers. A century ago, there were probably 230,000 orangutans - around four times as many as there are today.

Their dense forest home makes it difficult to determine population sizes, but the Bornean orangutan is estimated to number around 54,000 individuals, while there are around 6,600 Sumatran orang-utans.

The Sumatran orang-utan is now restricted to the north of Sumatra. It depends on high-quality primary forests, and is less able to tolerate habitat disturbance than Bornean orang-utans. Sumatran orang-utan densities reportedly fall by up to 60% with even selective logging.

The population is currently fragmented into 13 populations in 21 forest blocks. Only 6 of these populations boast more than 250 animals and are therefore regarded as viable in the long term, but even these groups are under threat due to ongoing habitat loss.

The Bornean orang-utan was once distributed throughout large areas of Kalimantan (Indonesia) and Sarawak and Sabah (Malaysia) on the island of Borneo. But its population has fallen by more than 50% over the past 60 years, while at least 55% of its habitat has disappeared over the last 20 years.

Most Bornean orang-utans are now found in Kalimantan, 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 are in the process of being converted to agriculture.

Three subspecies live in different parts of the island:
  • Northwest Bornean orang-utan is the most threatened subspecies with over 3,000 remaining.
  • Northeast Bornean orang-utans are the smallest in size. Around 16,000 live in Sabah and parts of eastern Kalimantan.
  • Central Bornean orang-utans are the most common subspecies with around 35,000 surviving.
     

What are the main threats?

Habitat loss is by far the greatest threat to orang-utans. Huge tracts of forest have been cleared throughout their range and the land used for agriculture, particularly palm oil - a product that is found in more than half of packaged products in supermarkets around the world.

Road development, illegal timber harvesting and unsustainable logging, mining and human encroachment also contribute to habitat loss, degradation and fragmentation.

Today, more than 50% of orang-utans are found outside of protected areas, in forests under management by timber, palm oil and mining companies.

But even protected areas are not secure since 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, oil palm companies and logging firms have encroached into all the parks.

Along with habitat loss, young orang-utans up to the age of seven are sought after for the illegal pet trade. When infants are targeted, usually the mother is killed so this trade represents a real threat to wild orang-utan populations.

In addition, orangutans are hunted in some areas for food. They are also sometimes killed when they move into agricultural areas and destroy crops.

And fire is also a major threat. In 1997-98, the drainage of peat-swamp forest contributed to uncontrollable fires in Kalimantan, which lasted for 6 months and killed up to 8,000 orang-utans.
Distribution of Sumatran orangutan, Sumatra, Indonesia. Map created by Ian Singleton with Riswan ... / ©: Ian Singleton with Riswan and Rachmadi A. Dadi.
Distribution of Sumatran orangutan, Sumatra, Indonesia. Map created by Ian Singleton with Riswan and Rachmadi A. Dadi. Source: 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.
© Ian Singleton with Riswan and Rachmadi A. Dadi.
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.
 / ©: Alain COMPOST / WWF
Loggers clearing a swamp forest for a palm oil plantation. (Illegal logging) Central Kalimantan, Indonesia.
© Alain COMPOST / WWF
Captive baby Sumatran Orang-utan (Pongo abelii). / ©: TRAFFIC SE Asia/Chris R. Shepherd
Captive baby Sumatran Orang-utan (Pongo abelii).
© TRAFFIC SE Asia/Chris R. Shepherd

What WWF is doing

WWF has been working on orang-utan conservation since the 1970s in partnership with local and international groups, including research institutions, universities, government bodies and local communities.
 
  • Conserving orang-utan habitat: We are working in both Borneo and Sumatra to secure well-managed protected areas and wider forest landscapes connected by corridors.
     
  • Promoting sustainable palm oil production: In 2004, WWF helped set up the Roundtable on Sustainable Palm Oil. This promotes the production and use of sustainable palm oil, which ensures that income is filtered down to local people and forests that are deemed to be of ‘high conservation value’ aren’t cut down to make way for oil palm plantations.
     
  • Engaging with timber companies to mitigate negative impacts on habitats and orang-utan populations. For example, studies show that Bornean orang-utans can fare well in logged forests if the impact is reduced through measures such as selective logging, keeping fruit trees intact, and controlling hunting.
     
  • Halting the illegal pet trade. We work with TRAFFIC (the wildlife trade monitoring network) to help governments enforce restrictions on the trade in live animals and orangutan products through the wildlife crime initiative. We also help to rescue orangutans from traders.
     
  • Reducing human orang-utan 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.
     
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. This vision includes a network of protected and sustainably-managed areas where hunting and illegal logging are prohibited.

How you can help

  • Adopt an orang-utan via WWF-UK  or WWF-US and support our work to protect orangutans
     
  • Buy sustainable wood, paper and palm oil. By purchasing certified sustainable palm oil and FSC-certified forest products, consumers, retailers, traders, and manufacturers help protect orang-utan habitat by limiting illegal logging and forest conversion to oil palm plantations.
     
  • Spread the word! Click on the button to share this information with others via email or your favourite social networking service.

  • Bookmark and Share
 / ©: Honing Heemskerk / WWF-Netherlands
Orang-utan (Pongo pygmaeus) sitting in tree in a rehabilitation centre in Malaysia.
© Honing Heemskerk / WWF-Netherlands

Did you know?

    • Orangutans are “gardeners” of the forest, playing a vital role in seed dispersal.

Please Donate

  • Our work is only possible with your support.

    Donate now
  • CITES logo
    The Convention on International Trade in Endangered Species (CITES) is an international agreement between governments, that aims to ensure that international trade in specimens of wild animals and plants does not threaten their survival and it accords varying degrees of protection to more than 33,000 species of animals and plants.

Subscribe to our mailing list

* indicates required
Donate to WWF

Your support will help us build a future where humans live in harmony with nature.

Enter Yes if you accept the terms and conditions
Enter Yes if you accept the terms and conditions