status: Endangered, IUCN Endangered, ESA
range: Brunei, Indonesia, Malaysia
Description and biology
The only great ape found in Asia, the orangutan is the largest living arboreal (tree-dwelling) ape. In the Malay language, its name means "forest person" or "man of the woods." With its long, powerful arms and hands and feet that can grasp branches, the animal moves easily from tree to tree. The orangutan's reddish brown coat is long and soft. It has small ears, a bulging snout, and a high forehead. An average orangutan has a head and body length of 30 to 40 inches (76 to 102 centimeters) and a shoulder height of 45 to 60 inches (114 to 152 centimeters). It weighs between 85 and 220 pounds (39 and 100 kilograms). Males are much larger and heavier than females.
Orangutans spend 95 percent of their lives in trees. During the day, the animals feed primarily on fruit. They also eat leaves, insects, bark, and young birds and squirrels. Each night, they build a nest in a tree 35 to 80 feet (11 to 24 meters) above
the ground. Their home range varies from 1 to 4 square miles (2.5 to 10 square kilometers).
The orangutan is a solitary animal. The only bond formed is between a mother and her infant. Mating, which can occur at any time during the year, is the only time males and females interact. They stay together for a few days to a few months until the female is pregnant, then they split up. After a gestation (pregnancy) period of 233 to 270 days, a female gives birth to one young. She raises the infant alone, keeping it constantly with her for the first year. She nurses the infant for up to three years. During a normal life span of 40 years, a female will bear only 4 or 5 offspring.
Habitat and current distribution
The orangutan inhabits a variety of forest habitats, including swampy coastal forests, mangrove forests, and mountain forests. It is found only on the Southeast Asian islands of Sumatra (part of the country of Indonesia) and Borneo (divided among Malaysia, Indonesia, and Brunei). In the mid-1990s, biologists (people who study living organisms) estimated that 12,000 to 20,000 orangutans existed on Borneo, while another 9,000 lived on Sumatra.
History and conservation measures
For thousands of years, the orangutan has been a victim of human abuse. Early humans considered it a food source and hunted it to the point of extinction in many areas. Orangutans once ranged throughout Southeast Asia. They now live on only 2 percent of that original range.
The greatest threat to orangutans is habitat destruction. The relentless clearing of rain forests to create plantations on the islands has reduced their habitat by 90 percent in the last 50 years. The animals are driven into forest areas that are too small to support them. Seeking food, the orangutans often wander onto nearby plantations. They are then killed or injured by workers protecting the crops.
In late 1997, orangutans and other wildlife in Southeast Asia suffered terribly from devastating wildfires and smoke that swept across the region. The fires resulted from man-made and natural causes. Farmers in the region rely on slash-and-burn agriculture, a process whereby a forest is cut down and all trees and vegetation are burned to create cleared land. When the El Niño weather pattern delayed the seasonal monsoon rains, hot and dry conditions fanned the fires. Many orangutans died in the fires or from smoke inhalation. Others were killed by frightened villagers as they escaped the burning forests. In 2000, the Indonesian news agency announced that the population of orangutan in Indonesia had dropped by one-third in the three years after the fires, noting that the animals had still not recovered. Individual orangutans were still found wandering outside their former habitat.
Another major threat to orangutans is capture. Thousands of females have been slaughtered so their offspring could be captured and sold as pets. Some childless couples even raise the animals as children, dressing them in human clothes. In the late 1980s and early 1990s, the demand for orangutan pets was especially strong in Taiwan, where a children's television show featured a pet orangutan. Of those infants that are captured in the wild, up to 50 percent die during transport.
Several protected reserves have been established in the orangutan's range, including the Gunung Lueser National Park in northern Sumatra and the Tanjung Puting National Park in Borneo. Conservationists and wildlife researchers have also established camps to help train orangutans that were once pets to return to their natural habitat. However, most of these orangutans have spent too much time among humans and cannot exist in the wild. In 2002, there was some good news. An expedition into the remote wilds of Borneo discovered a large and previously unknown population of the species, comprising perhaps the largest remaining orangutan population. But as clearing of the forests continues at a rapid rate, this population, too, is in jeopardy.
The orangutan (Pongo pygmaeus ), one of the Old World great apes, has its population restricted to the rain forests of the Indonesian islands of Sumatra and Borneo. The orangutan is the largest living arboreal mammal, and it spends most of the daylight hours moving slowly and deliberately through the forest canopy in search of food. Sixty percent of their diet consists of fruit, and the remainder is composed of young leaves and shoots, tree bark, mineralrich soil , and insects. Orangutans are long-lived, with many individuals reaching between 50 and 60 years of age in the wild. These large, chestnut-colored, long-haired apes are facing possible extinction from two different causes: habitat destruction and the wild animal trade.
The rain forest ecosystem on the islands of Sumatra and Borneo is rapidly disappearing. Sumatra loses 370 mi2 (960 km2) of forest a year, or about 1.6%, faster than any other Indonesian island. The rest of central Indonesia, of which Borneo comprises a major part, loses about 2,700 square miles (7,000 km2) per year. Some experts believe this estimate is too low, and they argue it could be closer to 4,600 mi2 (12,000 km2) per year. Another devastating blow was dealt Borneo's rain forests just over a decade ago, when more than 15,400 mi2 (40,000 km2) of the island's tropical forest was destroyed by drought and fire between 1982 and 1983. The fire was set by farmers who claimed to be unaware of the risks involved in burning off vegetation in a drought stricken area. Even though Indonesia still has over 400,000 mi2 (1,000,000 km2) of rain forest habitat remaining, the rate of loss threatens the continued existence of the wild orangutan population, which is now estimated at about 25,000 individuals.
Both the Indonesian government and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) have banned international trade of orangutans, yet their population continues to be threatened by the black market. In order to meet the demand for these apes as pets around the world, poachers kill the mother orangutan to secure the young ones, and the mortality rate of these orphans is extremely high, with less than 20% of those smuggled ever arriving alive at their final destination. This high mortality rate is directly due to stress, both emotional and physiological, on the young orangutans. The transportation scheme involved in smuggling these animals out of Indonesia to major trade centers throughout the world is intricate and time-consuming, and the way in which they are concealed for shipping is inhumane. These are two more reasons why only one out of five or six orangutan babies will survive the ordeal.
Some hope for the species rests in a global effort to manage a captive propagation program in zoos. A potentially self-sustaining captive population of more than 850 orangutans has been established. An elaborate system of networking and recording of all legally held individuals may also aid in the recognition and recapture of smuggled animals. Researchers have also developed methods of determining whether smuggled orangutans are of Bornean or Sumatran origin, thus providing a means of maintaining genetic integrity for those that can be bred in captivity or relocated.
[Eugene C. Beckham ]
Galdikas, M. F. Biruté, and Nancy Brigs. Orangutan Odyssey. New York: Harry N. Abrams, 1999.
Russon, Anne. Orangutans: Wizards of the Rain Forest. Buffalo: Firefly Books, 2000.
Orangutan Sanctuary. [cited May 2002]. <http://www.yorku.ca/arusson>.
Orang-outang. [cited May 2002]. <http://www.orang-outang.com>.
orangutan (ōrăng´ŏŏtăn), an ape, Pongo pygmaeus, found in swampy coastal forests of Borneo and Sumatra. Highly specialized for arboreal life, it usually travels by grasping branches with hands and feet and moving from tree to tree. Adult males are about 41/2 ft (1.4 m) tall and weigh up to 180 lbs (82 kg). Their arms are very long, the total span sometimes exceeding 7 ft (2.1 m). Their legs are short and bowed, making ground travel awkward; they walk with a side-to-side shuffle on all fours. The body is rotund and covered with long hair in various shades of red. The face of a young orangutan looks quite human; the name means
in Malay. Old males usually develop large cheek pads and facial hair that resembles a man's moustache and beard. Enormous throat pouches also develop with sexual maturation, which starts at about age 14.
Adult orangutans are basically solitary, except for mother-offspring pairs; however, weaned juveniles sometimes congregate in small groups. Males are aggressive toward each other and fight over females. Individual nests are usually constructed in trees each night. Fruit is a diet mainstay, and orangutans are important seed distributors.
The numbers of orangutans have recently dropped precipitously owing to loss of habitat to deforestation (logging, forest fires, and clearing of land for plantations) and the killing of females for their young, to be sold as pets or zoo animals. Fewer than 30,000 individuals are believed to remain in the wild, and the species is listed as endangered. Orangutans are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Primates, family Pongidae.
See B. Galdikas, Orangutan Adaptation at Tanjung Puting Reserve, Central Borneo (1978); J. H. Schwartz, The Red Ape (1987).
o·rang·u·tan / əˈrang(g)əˌtan/ (also orangutang, orang-outang / ōˈrang(g)əˌtang/ , orang-utan) • n. a large mainly solitary arboreal ape (Pongo pygmaeus, family Pongidae) with long reddish hair, long arms, and hooked hands and feet, native to Borneo and Sumatra. The mature male develops fleshy cheek pads and a throat pouch.