The Bornean Orangutan, Pongo pygmaeus, is one of the world’s great ape species and the only great ape native to Asia. These primates are found exclusively on the island of Borneo, inhabiting its dense, tropical rainforests. The species is recognized for its solitary nature and strictly arboreal lifestyle, spending nearly all its life high in the forest canopy. Their survival is dependent on the health and extent of the forests within this Southeast Asian island.
The Geographic Scope of Borneo
The island of Borneo is politically divided among three sovereign nations, which defines the overall range of the Bornean Orangutan. The largest portion of the island, known as Kalimantan, belongs to Indonesia and holds the majority of the remaining orangutan population. Malaysia administers the northern parts of the island, which include the states of Sarawak and Sabah, where significant populations also reside. The Sultanate of Brunei shares the north coast, but permanent, established orangutan populations are rare or unconfirmed within its borders. The species’ distribution across these political boundaries complicates conservation efforts, as regional governments must coordinate to protect fragmented habitats.
Preferred Ecosystems and Elevation
The Bornean Orangutan demonstrates a strong preference for specific types of tropical lowland forests, which offer the most consistent food resources. Their primary habitat includes mixed dipterocarp forests, named for the dominant tree family that features prominently in the canopy structure. They also thrive in both peat swamp forests and tropical heath forests, particularly where fruit availability is high throughout the year. The density of orangutans is often highest in these lowland mosaic habitats, where they can forage on a wide variety of foods, including the wild figs and durians that constitute a large part of their diet.
These great apes are predominantly found at lower elevations, rarely venturing above 500 meters above sea level. The concentration in the lowlands is directly related to the greater abundance of fruit-bearing trees in these areas. While they have occasionally been recorded at higher altitudes, sometimes reaching up to 1,500 meters, this is generally considered the limit of their vertical range. The canopy of the lowland forests provides both the food supply and the necessary structure for their nesting and movement.
Regional Subpopulations and Range
The Bornean Orangutan is currently recognized as having three distinct subspecies, each inhabiting a specific region of the island. Geographic barriers, such as major rivers and mountainous terrain, historically separated these groups, contributing to their genetic differentiation. The current distribution is highly fragmented, with human development creating isolated pockets of habitat. This fragmentation, driven by land conversion for agriculture and logging, has severely reduced the connectivity between these regional populations.
Northwest Bornean Orangutan
The Northwest Bornean Orangutan (Pongo pygmaeus pygmaeus) is found in the Malaysian state of Sarawak and the Indonesian province of West Kalimantan.
Southwest Bornean Orangutan
The Southwest Bornean Orangutan (Pongo pygmaeus wurmbii) is located centrally on the island, spanning West and Central Kalimantan in Indonesia.
Northeast Bornean Orangutan
The Northeast Bornean Orangutan (Pongo pygmaeus morio) occupies the eastern provinces of North and East Kalimantan in Indonesia, as well as the state of Sabah in Malaysia.