ORANGUTAN

( (Malaysian: man of the forest), ) also spelled Orangoutan, also called Orang (species Pongo pygmaeus), large manlike ape (family Pongidae) that is now restricted to lowland swamp forests in Borneo and a small part of Sumatra. Orangutans formerly lived in the jungles of mainland Southeast Asia as well, and the principal cause of the extreme shrinkage of their range in the last few thousand years seems to have been hunting by humans. Like the related gorilla and chimpanzee, the orangutan has a short, thickset body, long arms, and short legs. It differs in having a shaggy, reddish coat, an even greater disproportion between arm and leg lengths, and a differently shaped skull. The male orangutan may be about 137 cm (4.5 feet) tall and weigh about 85 kg (185 pounds) when mature, while females usually attain a weight of only about 40 kg (90 pounds). The male orangutan is strikingly different from the female not only in being considerably larger but also in having cheek flaps of subcutaneous fatty tissue and an air sac that forms a baglike swelling hanging from the throat. A young orangutan in the tropical-evergreen forest of northern Borneo, Sabah, East Malaysia. The orangutan is mostly arboreal and is active in the daytime. It uses all four of its limbs when walking or climbing along branches in the forest canopy, and it may swing from one branch to another, though it is much less active in this regard than its cousin, the gibbon. Adult male orangutans must sometimes descend to the ground to travel long distances, since the smaller tree branches cannot support their weight. When walking, orangs place the clenched fist (rather than the knuckles) on the ground to aid locomotion. The orangutan feeds mainly on wild figs and other fruits that it picks from trees, though it also eats smaller quantities of leaves, bark, and even insects. Each night it constructs a sleeping platform in the trees out of interwoven branches. Unlike virtually all other apes and monkeys, adult orangutans are solitary animals that come together only for a brief courtship before mating. Their population densities in the forest are low, with only two or three per square mile. A single young is born after a gestation period of about 275 days and is nursed by the mother, who carries it at her breast or on her back. The young is usually completely weaned at the end of 3 years, by which time the mother has mated again. Baby and adolescent orangs are noticeably more social than adults. Sexual maturity is attained at 8 years in the female, 10 years in the male. Life span, at least in captivity, may exceed 30 years. The orangutan is remarkably silent; among its few vocalizations are grunts, lip-smacking, and the long call of the adult male; the latter is a loud sequence of roars that presumably specify his location to other orangs. By nature, the orangutan is a placid, deliberate animal. It is highly intelligent, and in captivity it has shown considerable ingenuity and persistence, with a particular ability to manipulate mechanical objects. The Red Data Book lists the orangutan as an endangered animal. Factors contributing to the decline in its population include hunting and the destruction of its habitat by humans. It is protected by law in Indonesia and Malaysia.