Orangutan
(Pongo pygmaeus)
Habitat
Lower and middle canopy levels of mature lowland tropical rain forests. Lower densities in mountainous areas.
Height
Males up to 5 feet (1.6 m)
Females up to 3.5 feet (1 m)
Weight
Males 155-200 pounds (70-90 kg)
Females 65-110 pounds (30-50 kg)
Life Span
30-40 years in the wild; up to 60 years in captivity
Diet
In the wild: predominantly fruit, leaves, flowers, bark, occasional bird eggs, insects and mineral-rich soil.
At the zoo: Lettuce, celery, broccoli, high-fiber biscuits, apples, oranges, bananas and other tropical fruits, eggs and fresh browse when available.
Reproduction
Females become sexually mature at around ages 7 or 8 and reproduce until age 25 or older. Although males reach sexual maturity shortly after females, they often do not breed until ages 15-20 when they become large enough to compete successfully for females with other large male orangutans.
Gestation period is about eight to nine months. Females usually bear single young; twins are rare. Average birth weight is 3.5 pounds (1.6 kg). Females reproduce approximately every seven or eight years.
Life Cycle
Young orangutans are dependent on their mothers for survival during the first five years of their lives. Since young orangutans have few instinctive behaviors, they must learn from watching their mothers. Between 3 and 7 years, orangutans become increasingly independent, and leave their mothers by ages 5 to 8.
Orangutan - People of the Forest
In the Malay language, orang means "people" and utan "forest," thus orangutan literally means "people of the forest." Highly intelligent, orangutans have long, coarse hair ranging in color from bright orange to maroon or dark chocolate. Older Bornean males develop massive cheek pads and large throat pouches while Sumatran males have smaller pads and pouches. Males inflate their pouches to make loud vocalizations referred to as "long calls."
Rarely descending from trees, orangutans have nearly identical hook-shaped hands and feet that are well adapted for grasping and hanging from tree limbs. Young orangutans easily swing from limb to limb. Older, heavier adults must move through the forest slowly, using their hands and feet to test each branch to see if it will hold their weight. When required, however, an adult orangutan can move very fast.
Social Organization - The Solitary Life
Unlike gorillas and chimpanzees who live in large male/female social groups, male orangutans are mostly solitary animals. Females may live in small groups composed of dependent young, other adult females and adolescents. The load-bearing limits of rain forest tree tops, combined with the scarcity of fruit, keep orangutans from living in large social groups.
During courtship and mating, however, adult male and female orangutans travel and forage together. The long call of a dominant male, audible for up to a mile (1.6 km), announces his presence to females who are ready to mate. The call also scares away other, less dominant males. Females seek out the male to breed, but after a few days they separate and return to their solitary life.
Location at the Zoo
Woodland Park Zoo's orangutan forest, located at the Trail of Vines exhibit in Tropical Asia, brings visitors eye-to-eye with orangutans in their treetop habitat. Visitors have an unobstructed view to observe orangutans as they may behave in the wild. The exhibit also has an indoor area complete with a "feeding station" similar to those at rehabilitation sites in the jungles of Sumatra and Borneo. These rehabilitation programs work with orangutans that have been confiscated from smugglers and private owners.
Conservation Connection
Orangutans are an endangered species. Overpopulation, logging, agriculture and other human activities are rapidly destroying forest environments required by orangutans for survival. While population densities are hard to determine, estimates for the Bornean subspecies are 12,000-13,000 while the Sumatran subspecies has dwindled to a mere 6,500-7,500 animals. Recently, due to the 1997 drought caused by El Niño, nearly 2 million acres (800,000 h) of forest were destroyed by forest fires on the island of Borneo. This incredible ecological disaster means even less habitat for orangutans. Additionally, the economic stability of both Malaysia and Indonesia is suffering greatly due to the crash of their stock markets and value of their currencies. Both of these events mean orangutans need more support from conservationists than ever before.
Woodland Park Zoo is involved in orangutan research and conservation in the wild. Zoo staff traveled throughout Indonesia doing tissue sampling of wild and captive orangutans. This study confirmed that the two orangutan subspecies are very different genetically, and should be managed separately and not allowed to interbreed. While the zoo's resident orangutans are hybrids (crossbred between Bornean and Sumatran subspecies), and therefore are not allowed to reproduce, these animals play a critical role in educating zoo professionals and the public about the amazing orangutan. As an example, the first orangutan in vitro fertilization was accomplished at Woodland Park Zoo. Although no offspring resulted, it was an important step in the continuing development of embryo transfer techniques.
How You Can Help!
You can help preserve and protect wildlife and their habitat. Join and become active in Woodland Park Zoo and other conservation organizations of your choice. Please do not buy products made from wild animal parts.
Contact Woodland Park Zoo at webkeeper@zoo.org to find out about ways you can support conservation programs at the zoo. Discover more about endangered orangutans by visting the Balikpapan Orangutan Society web site. Learn other ways you can help conserve wildlife and the habitats they require for survival by visiting our How You Can Help page.
Sources and Suggested Reading
Galdikas, Birut, M.F. 1995. Reflections of Eden: My Years with the Orangutans of Borneo. Little, Brown and Company, Boston, MA. 408 p.
Kaplan, Gisela & Rodgers, Lesley. 1994. Orang-utans in Borneo. University of New England Press, Armidale, NSW, Australia. 196 p.
For Kids!
Zoo Books. 1996. Orangutans. Wildlife Education Ltd., San Diego, CA. 21 p.
Listed on Appendix 1 of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).