Orangutan

Order: Primates
Family: Pongidae
Genus and Species: Pongo pygmaeus (Bornean) and Pongo abelii (Sumatran)

The world's largest tree-dwelling animal, the orangutan relies upon its intelligence and well-adapted body to survive in the tropical rainforest.

Physical Description

These orangish-red-haired great apes have long arms and curved hands and feet, which they put to good use when traversing the treetops. Older orangutans usually move through the trees on all fours, while young ones often brachiate, or swing hand over hand. Males have longer hair than females and disc-like cheek pads.

Both sexes have throat pouches that make their calls resonate through the forest. The males' pouches are more developed. Orangutans crush tough foliage and hard-shelled nuts with their strong teeth and jaws. Two species exist: P. pygmaeus of Borneo, and the Sumatran species, P. abelii. Outside of their native ranges, they can be differentiated only through chromosomal or DNA analysis.

Size

Orangutans are Asia's largest primates, and males are larger than females. Males stand about four and a half feet tall and weigh 130 to 200 pounds. Females stand about four feet tall and weigh 90 to 110 pounds. Zoo animals are often heavier.

Geographic Distribution

Once more widely distributed, orangutans now live only in forests on the Southeast Asian islands of Sumatra and Borneo.

Status

The Sumatran species is listed as critically endangered and the Bornean species is listed as endangered on the World Conservation Union's Red List of Threatened Animals.

Habitat

Orangutans live in tropical rainforests, including hill forests and swamp forests.

Natural Diet

Orangutans feed primarily on forest fruits, including durians, jackfruits, lychees, mangos, and figs. Leaves and shoots make up the remainder of their diet, supplemented occasionally by small animals, tree bark, and soils rich in minerals. Researchers have documented more than 400 different foods eaten by wild orangutans.

Reproduction

Male orangutans establish home ranges that embrace those of several females. Females reach maturity at around ten years of age and can remain fertile for more than 30 years. Recent research suggests that, on average, wild females give birth only every eight years. Young orangutans may nurse until age six, and stay close to their mothers until the next offspring comes along.

Life Span

Orangutans may live about 35 years in the wild, and up to 60 in zoos.

Behavior

Active during the day, orangutans spend much of their lives high in the trees. Solitary, they rarely encounter others of their kind unless sharing a fruiting tree or mating. Each night, orangutans bend branches into nest platforms that support the apes while they sleep in the trees.

Orangutans move slowly through the forest, seeking fruiting trees, which they may find by following the movements of hornbills and other fruit-eaters. When heavily fruiting trees are found, orangutans will spend many hours feeding.

Past/Present/Future

Once widespread in Asian tropical forests, orangutans now live only on Sumatra and Borneo, where forest loss is the greatest threat to their existence. Naturally occurring forest fires, and those set by farmers and large companies to clear the way for plantations of oil palm, fast-growing pulpwood, and other crops, devastate forests. The destruction spreads even further during dry years. In 1997, an area the size of New Jersey burned in Indonesia, and many of the fires occurred in orangutan habitat. Large reserves and strictly enforced wildlife protection laws are needed to keep orangutans safe from extinction.

A Few Orangutan Neighbors:

proboscis monkey (Nasalis larvatus): A large vegetarian that lives in forests near water only on Borneo. Males are twice the size of females and have bulbous noses.

Asian small-clawed otter (Amblonyx cinerea): This small, social otter frequents streams and swamp forests, where it eats crabs and other small animals.

white-crowned hornbill (Aceros comatus): One of five species of large, long-billed fruit-eating birds that share forests with orangutans on Sumatra and Borneo.

By saving orangutan habitat, we protect these and many other animals.

Fun Facts:

In Malay, "orang utan" means "person of the forest."

An adult orangutan's arms can be well over seven feet from fingertip to fingertip.