Class: Mammalia (Mammals)
Length: males—about 40 inches (102 centimeters) from top of head to rump; females—about 30 inches (76 centimeters)
Weight: males—110 to 198 pounds (50 to 90 kilograms); females—66 to 110 pounds (30 to 50 kilograms)
Life span: up to 59 years in zoos
Gestation: about 8.5 months
Number of young at birth: usually 1, sometimes 2
Size at birth: 3.3 to 4.5 pounds (1.5 to 2 kilograms)
Age of maturity: males—about 15 years; females—about 12 years
Conservation status: Sumatran orangutan is at critical risk; Bornean orangutan is endangered
If you think orangutan arms look long, you’re
right! Their arms stretch out longer than their bodies—over
7 feet (2 meters) from fingertip to fingertip!
When they are about 15 years old, male orangs develop large cheek pads. Female orangs find these pads very attractive!
The male’s pads have another purpose besides impressing females. When males are fighting, they charge at each other and break branches. And if that doesn’t scare one of them away, they grab and bite each other on the cheek pads or ears until one of them gives up and runs away!
For its first few weeks of life, a young orang holds tight to its mom’s belly as she swings through the forest in search of fruit. Then when it is older and better at balancing, it rides "piggyback" so it can see what’s going on.
Listen to an orangutan!
Orangutans are the loners and the daydreamers of the great apes. While chimps, bonobos, and gorillas are usually found in groups called troops—socializing, foraging, or playing—orangutans tend to be more solitary. It’s not that they don’t do all the things the other great apes do, it’s just that they seem to have a more internal approach to everything. While other apes might go from tree to tree searching for fruit, an orangutan will just sit in the forest canopy for hours on end until the location of the hidden fruit seems to mysteriously reveal itself. Then it will swing over for its meal. Orangutans have even been known to watch villagers use boats to cross the local waterways, and then untie a boat and ride it across the river on their own!
Relaxed problem solvers
Scientists like to explain the orangutan’s unique approach to problem solving with this example: If a chimp is given an oddly shaped peg and several different holes to try to put it in, the chimp will immediately try shoving the peg in various holes until it finds the hole that the peg fits in. But an orangutan will approach the challenge quite differently. It will stare off into space, or even scratch itself with the peg. Then, after a while, it will offhandedly stick the peg into the correct hole while looking at something else that has caught its interest!
Orangutans are also known for their clever ability to get into places they’re not supposed to go! One of the San Diego Zoo’s most famous orangutans was Ken Allen, a Bornean orangutan Pongo pygmaeus pygmaeus known for his creative escape techniques. He would unscrew bolts with his fingers, reach around to unlatch things, climb up a steep incline by the back of his enclosure to slip over a wall, and so on.
Every time keepers figured out one of his escape routes, he would discover a new one. He never seemed to mind being led back into his enclosure—he just seemed to enjoy the challenge of finding a new way out! Ken Allen became a San Diego Zoo legend, with his own fan club and T-shirts, bumper stickers, and songs created in his honor. Many people were saddened when this gentle, mischievous ape developed cancer and passed away in December 2000.
Life with mom
In the wild, young orangutans usually stay with their mothers until they’re about eight years old or older. Orangutans have the longest childhood of the great apes because, when they grow up, they don’t have a troop around to give them more lessons. The solitary animals must learn all the lessons of finding fruit, building night nests, and other survival techniques before they set off on their own. Fruit trees are spread out over the rain forests where orangutans live, and they all flower and fruit at different times. So the youngsters learn a mental map of the forest layout and where ripe fruit is likely to be at any given time. They also learn to eat insects and birds’ eggs. At the San Diego Zoo, the orangutans are offered cabbage, romaine lettuce, kale, carrots, yams, broccoli, bananas, apples, oranges, and grapes. Treats might include papaya, corn, turnip, onion, popcorn, raisins, peanut butter, and walnuts. The orangutan's motto is: food should never be boring!
Orangutans spend most of their lives in trees and travel by swinging from branch to branch with their long arms. They usually build a new nest every night, but occasionally reuse one. The apes also use leafy branches to shelter themselves from rain and sun, and sometimes they even drape large leaves over themselves like a poncho! Sometimes several mothers and their young encounter each other by a fruit tree within their overlapping ranges. They peacefully feed together and watch their youngsters play. Males, however, generally don’t care for company—especially from other males. If a male accidentally swings into a more dominant male’s territory, the dominant male gives a booming roar to scare him off. During mating season, the male orangutans’ calls also serve as an invitation to any females within hearing distance.
A precarious future
Unfortunately, these highly intelligent red apes are now extinct in much of Asia. Farming, logging, and the burning of the forest have destroyed 80 percent of the rain forests where orangutans used to make their homes. On top of that, poachers often kill orangutan mothers and sell their young in the illegal pet trade. In those cases, the orangutan orphan is usually doomed to a short and depressing life, unless it is rescued by an orangutan organization that takes care of orphans in special reserves. Many of these organizations have programs to educate loggers and local people about the need to protect their rare red neighbors and to help enforce the laws against poaching.
Great ape awareness
San Diego Zoo Global is involved with some of these worthy organizations, working to raise awareness about the dangers all great apes face. Come out and support the apes!