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

Key facts

  • Species

    Sumatran orangutan (Pongo abelii), Bornean orangutan (Pongo pygmaeus)

  • Location



  • Sumatra (Indonesia), Borneo (Malaysia and Indonesia)
  • Status

    Endangered to Critically Endangered

Species news

  • UN recognizes severity of wildlife crimes

    Members of the United Nations Commission on Crime Prevention and Criminal Justice Friday passed a resolution encouraging UN member states “to make …

    26 Apr 2013

Victims of logging and fire

Orangutans share a preference with humans for fertile alluvial plains and lowland valleys – a habitat once rich in tropical forests but now being replaced with logging and agricultural concessions.   Each of the two orangutan species is found only on the island from which it derives its name: Sumatra or Borneo. With numbers having fallen drastically over the past century and human pressures increasing, orangutans may be lost from the wild forever within a few decades.

Physical description 

The orangutan is the world’s largest tree-climbing mammal. The animals have a characteristic ape-like shape, shaggy reddish fur and grasping hands and feet. Their long armsvery long arms that can reach as much as 2 meters in length. Orangutans’s legs are relatively short and weak, but their hands and arms are powerful.
There are 2 different types of adult male orangutan: “flanged” & “unflanged”. Flanged males have a long coat of dark hair on their back, a facial disk, flanges and a throat sac used for “long calls”. 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. Orangutans are the only primate in which this biological phenomenon occurs.
Size: 1.25-1.5m in length;  females weigh 30-50kg, males weigh 50-90kg
Colour: Reddish brown

The ‘man of the forest’

Orangutans live in primary and secondary forests. Although they can occur up to 1,500 meters above sea level, most are found in lowland areas and prefer forests in river valleys or floodplains.
Orangutans travel about by moving from one tree to another, and usually avoid climbing down to the ground – although there are differences between the two species. When on the ground, they move on “all fours”, with clenched fists placed on the ground.
Orangutans make a nest of vegetation to sleep in at night, and rest in smaller nets during the day to rest. Social structure Adult orangutans are generally solitary, although temporary aggregations  are occasionally formed. The large home ranges of males overlap with the  ranges of several adult females. Adult males are generally hostile to  one another, although they do not display territoriality.  Life cycle Orangutans usually give birth to a single young, or occasionally twins. 
After weaning at about 3.5 years of age, young individuals become  gradually independent of their mother after she gives birth to a second  young. 
Orangutan females first reproduce at around 10-15 years of age, depending on the species/subspecies. Females give birth probably not more than once every 5 years, and the interbirth interval can be as long as 10 years. The long time taken to reach sexual maturity, the long interbirth  periods, and the fact that orangutans normally give birth to just a  single young mean that orangutans have an extremely low reproductive  rate. This makes orangutan populations highly vulnerable to excessive  mortality, and means that populations take a long time to recover from  population declines.  Diet About 60% of the orangutan’s diet includes fruit (e.g. durians,  jackfruit, lychees, mangosteens, mangoes and figs), while the rest  comprises of 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. 

Population & distribution

Previous population & distribution Pleistocene fossil records in southern China, northern Vietnam, Lao PDR, and Java indicate that the genus once had a  wide distribution in Southeast Asia.
Orangutans are now only found on the islands of Borneo and Sumatra, with populations on each island belonging to separate species. A century ago there were probably more than 230,000 orangutans worldwide.
Current population & distribution Both orangutan species have experienced sharp population declines over the past few decades.
Their dense forest homes make it difficult to precisely determine population sizes, however the Bornean orangutan is estimated to number about 41,000 individuals, while the Sumatran orangutan is estimated to number about 7,500 individuals.

Male Bornean Orang-utan (Pongo pygmaeus) / ©: David Lawson / WWF-UK

Flanged male Bornean orangutan (Pongo pygmaeus)
© David Lawson / WWF-UK

Priority places


Major habitat type Tropical and Subtropical Moist Broadleaf Forests
Biogeographic realm Indo-Malayan
Range States Indonesia, Malaysia
Ecological Region Borneo Lowland and Montane Forests, Kinabalu Montane Shrublands,  Sundaland Rivers and Swamps
Tree emerging from tropical rainforest. Gunung Leuser National Park, Sumatra, Indonesia.  / ©: Alain Compost / WWF-Canon

Tree emerging from tropical rainforest. Gunung Leuser National Park, Sumatra, Indonesia.
© Alain Compost / WWF-Canon

What are the main threats?

Habitat loss Habitat destruction and fragmentation is by far the greatest threat to orangutans.
Huge tracts of forest have been cleared throughout the their range, through legal and illegal logging and forest conversion for oil palm plantations and other agriculture. Fires related to these activities also pose a serious threat to both orangutans and their habitat.
Today, more than 50% of orangutans are found outside of protected areas, in forests under management by timber, palm oil and mining companies. Hunting & illegal trade Orangutans are an easy target for hunters, being large and slow targets. 
The animals are killed for food in some areas, or in retaliation when they move into agricultural areas and destroy crops. This occurs more in times of environmental stress when orangutans can’t find the food they need in the forest.
Females in particular are most often hunted. When caught with offspring, the young are often kept as pets.
This pet trade is a major problem. It is thought that for each orangutan reaching Taiwan, as many as 3-5 additional animals die in the process. Recent enforcement of the law in Taiwan has reduced the importation of orangutans, but the trade remains a threat in Indonesia where there is still demand for orangutans as pets.
There is also trade in orangutan skulls in Kalimantan (Indonesian Borneo). 

 / ©: Alain COMPOST / WWF-Canon

Loggers clearing a swamp forest for a palm oil plantation. (Illegal logging) Central Kalimantan, Indonesia.
© Alain COMPOST / WWF-Canon
 / ©: Chris R. Shepherd - TRAFFIC Southeast Asia

A Sumatran orang-utan, confiscated in Aceh, stares through the bars of its cage
© Chris R. Shepherd – TRAFFIC Southeast

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