The orangutan is a large, highly intelligent great ape that lives exclusively in Southeast Asia. It is the only great ape found outside of Africa, and its name means “person of the forest” in Malay and Indonesian. Orangutans are distinguished by their long, reddish-brown hair and arboreal lifestyle, spending nearly all their time in the forest canopy. They are confined solely to two islands.
The Exclusive Geographical Range
Orangutans are found only on the islands of Borneo and Sumatra, which are part of the Indo-Malay archipelago. This makes them one of the most geographically restricted great apes, with a range significantly smaller than their historical distribution which once extended into mainland Asia. Borneo is politically divided among three nations. The majority of the island, known as Kalimantan, is governed by Indonesia, while the northern part is divided into the Malaysian states of Sabah and Sarawak. Brunei also shares the island but does not contain permanent, wild orangutan populations.
Sumatra, in contrast, is entirely contained within Indonesia. On Sumatra, populations are concentrated in the northern provinces of Aceh and North Sumatra. The presence of these apes only within Indonesia and Malaysia makes their conservation a shared, binational responsibility.
Distinct Species Across Their Range
The limited geographical distribution is home to three distinct species of orangutan. The Bornean Orangutan (Pongo pygmaeus) is the most numerous and robust. Bornean orangutans are found throughout Borneo and are generally more terrestrial than their Sumatran cousins, occasionally descending to the forest floor.
Sumatra hosts two species: the Sumatran Orangutan (Pongo abelii) and the Tapanuli Orangutan (Pongo tapanuliensis). Sumatran orangutans, found north of the Lake Toba region, are more slender, have longer facial hair, and are more strictly arboreal. The Tapanuli Orangutan, identified in 2017, has an extremely restricted range in the Batang Toru ecosystem, south of Lake Toba. This species is physically distinguishable by its frizzier hair, flatter face, and smaller skull.
Critical Habitat and Conservation Status
The survival of all three species is linked to the health of their preferred habitat: lowland tropical rainforests. Orangutans rely heavily on these forests, often favoring areas like peat swamp forests and mixed dipterocarp forests that provide a high density of fruit trees. They are the largest mammals that spend nearly their entire lives in the trees, making the integrity of the forest canopy necessary.
Their limited range and specific habitat requirements make orangutans highly vulnerable to human activity. Deforestation, primarily driven by the expansion of palm oil and agricultural plantations, has severely fragmented and reduced their forest homes. As a result of this habitat loss, all three species—Bornean, Sumatran, and Tapanuli—are classified as Critically Endangered by the International Union for Conservation of Nature (IUCN). The Tapanuli Orangutan, with a population estimated at fewer than 800 individuals, is particularly imperiled by its tiny, isolated location.