Where Do Orangutans Live? Borneo and Sumatra Rainforests

The two islands orangutans call home

Borneo, the third-largest island in the world, is shared by three countries: Indonesia (the provinces of Kalimantan), Malaysia (the states of Sabah and Sarawak) and the small nation of Brunei. Orangutans live in Indonesian and Malaysian Borneo; whether any survive in Brunei is uncertain. Sumatra, the sixth-largest island, belongs entirely to Indonesia, and its orangutans are restricted to the northern provinces of Aceh and North Sumatra.

Orangutans once lived much more widely. Fossil teeth show that during the Pleistocene, the ice-age epoch that ended about 11,700 years ago, they ranged across mainland Southeast Asia, southern China and Java. They disappeared from those areas long ago, probably because of changing forests and hunting by people.

Where each orangutan species lives

There are three species of orangutan, and each has its own range.

The Bornean orangutan is split into three subspecies in different parts of the island: one in Sarawak and northern West Kalimantan, one in southern West and Central Kalimantan, and one in East Kalimantan and Sabah. Large rivers and mountains separate them.

The Sumatran orangutan lives north of Lake Toba, with most animals in the Leuser Ecosystem, a vast area of forest that includes Gunung Leuser National Park. The Tapanuli orangutan lives south of Lake Toba in an area of only about 1,000 km² (390 sq mi) of hilly forest, which makes it the rarest great ape in the world. To learn how the three differ, see how many orangutan species are there?

What kind of forest do orangutans need?

Orangutans need large areas of tall, fruit-rich tropical forest. The best habitats are:

• Peat swamp forest, waterlogged forest growing on deep layers of peat. Some of the largest remaining Bornean populations, such as in Sabangau, live in peat swamps.
• Lowland dipterocarp forest, dominated by tall dipterocarp trees, with many fig trees and fruiting vines.
• Freshwater swamp and riverside forest, where fruit tends to be abundant.
• Hill and mountain forest, used less often. Bornean orangutans are found up to about 1,500 m (4,900 ft), and Tapanuli orangutans live mainly between about 300 and 1,300 m (980–4,300 ft).

Densities are highest in lowland and swamp forests below about 500 m (1,600 ft) and fall with altitude, because higher forests produce less fruit. Orangutans can survive in selectively logged forest and sometimes visit plantations and gardens, but they cannot live long-term in oil palm plantations or cleared land.

Life in the canopy

Orangutans are the most tree-dwelling of all great apes. They feed, travel, rest and sleep in the trees, moving by climbing, hanging below branches and swaying slender trunks to cross gaps. Each evening they build a sleeping nest from bent and woven branches, usually 10 m (33 ft) or more above the ground.

How much time they spend on the ground depends on where they live. Bornean orangutans, especially heavy adult males, walk on the ground fairly often. Sumatran and Tapanuli orangutans almost never do, probably because Sumatra has tigers. In over 3,000 hours of observation, researchers did not see Tapanuli orangutans come down to the ground.

How big is an orangutan’s home range?

Orangutans do not defend territories, but each animal uses a familiar home range. Females typically use a range of a few square kilometers, often settling close to where their mothers live. Adult males roam much larger areas that overlap the ranges of several females, and some young males wander far before settling.

Home ranges are larger where fruit is scarce, so orangutans in poorer hill forests need more space than those in rich swamp forests. This is one reason why small, isolated patches of forest cannot support healthy populations. Orangutans also follow the fruiting of trees across the forest, so they need room to move between areas as different trees come into fruit through the year. In many places, young males leave their birth area and travel long distances before settling, which helps keep populations genetically mixed when forests are still connected.

Why orangutan habitat is shrinking

Large parts of lowland Borneo and Sumatra have been cleared for oil palm and pulpwood plantations, logging, mining and farming, and drained peat swamps have burned in severe fire years such as 2015. Roads and plantations also cut the remaining forest into fragments. All three orangutan species are now Critically Endangered on the IUCN Red List. Find out more in why are orangutans endangered?