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Sumatran orangutan (Pongo abelii), Bornean orangutan (Pongo pygmaeus)
Sumatra (Indonesia), Borneo (Malaysia and Indonesia)
Endangered to Critically Endangered
Victims of logging and fire
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.
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
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.
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.
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.
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.
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.
Tropical and Subtropical Moist Broadleaf Forests
Borneo Lowland and Montane Forests, Kinabalu Montane Shrublands, Sundaland Rivers and Swamps
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 (China) 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).
- Conserving orangutan habitat: We are working in both Borneo and Sumatra to secure well-managed protected areas and wider forest landscapes connected by corridors.
- Promoting sustainable forestry and agriculture: Our work on sustainable production of commodities – including forest products and palm oil – also contributes towards the protection and conservation of major orangutan habitats on the islands, as well as to mitigating human-orangutan conflict.
- Halting the 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. 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.
» More on our orangutan work in Borneo
» More on our orangutan work in Sumatra
- Adopt an orangutan through WWF-UK or WWF-US and support our work to protect orangutans (international adoptions possible)
- 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 orangutan habitat by limiting illegal logging and forest conversion to oil palm plantations.
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