Animals

Orangutans

by Marcia Malory

An orangutan is a great ape that is a member of the genus Pongo.

There are two living species of orangutan: the Sumatran orangutan (Pongo abelii), which is found only on the island of Sumatra, and the Bornean orangutan (Pongo pygmaeus), which is confined to the island of Borneo.

Orangutans live in forests, mangroves and swamps.

They have long, shaggy, reddish brown hair.

An orangutan can have a pink, red or black face. It has a high, sloped forehead and a prominent snout.

Male orangutans are much larger than females.  Males can reach up to 6 feet (1.5  meters) tall and can weigh between  110 and 200 pounds (50 and 90 kilograms.) Females are usually 3 to 4 feet (1 to 1.3 meters) tall and weigh between 65 and 110 pounds (30 and 50 kilograms).

OrangutanMales have longer hair than females.

A male orangutan has large cheek pads that are made of fat and connective tissue.

One of the orangutan's most recognizable features is its long arms. The arm span of an orangutan can be longer than the height of its body. These long arms help the orangutan Save brachiate (swing from tree to tree).

An orangutan's wrist contains a ball and socket joint; this allows it to rotate its wrist very easily when it is holding on to a branch.

Most orangutans spend almost all of their time in trees.  The orangutan is the largest arboreal animal in the world.

An orangutan will sleep in a tree nest made out of branches, sticks and leaves.

Most of an orangutan's diet consists of tree fruit. However, orangutans also eat nuts, leaves, flowers, tree bark, insects, egg and honey.

Older males may be so heavy that arboreal life is no longer convenient for them. They spend most of the time on the ground, walking on their feet and fists, and making nests for themselves on the ground. Heavier males still venture into the trees in order to find food, however.

When older orangutans move through the trees, they tend to walk on all their fists and feet, rather than brachiate.

Orangutans are solitary animals.  They usually travel alone.  A female may be accompanied by one or two young. Very small groups, consisting of only two females and their young, sometimes accompanied by an adult male, may form. Males are strongly territorial. They have throat pouches that they can inflate to produce long, loud calls to warn each other away.

Females also have throat pouches that amplify sounds; however, these pouches are not as well developed as the males' throat pouches.

If two males meet, they may fight to the death.

Females are more social than males.

Sometimes females will congregate at feeding sites for short periods.

A male's home range will usually contain the home range of several females.

Both male and female orangutans can have multiple sexual partners.

When a female is ready to breed, she will seek out the local dominant adult male. Sometimes, subadult males will rape females.

Male orangutans use their throat pouches to make calls to attract females.

A female orangutan will have her first child when she is about 15 years old.

Orangutans usually give birth to one child at a time.  A female may have twins.

A young orangutan will nurse for four years. During that time, the mother will not give birth to any more children.  The span between births can range from four to eight years.

Male orangutans are not involved in childcare.

A child will stay with its mother until it is between seven and ten years old. Females mature faster than males.

An orangutan will usually live for 40 to 50 years, although some can live to be close to 60.

Orangutans play an important role in rainforest ecology. As they move about in the trees, they open up spaces in the canopy of forest.  This allows sunlight to reach the rainforest floor.

Additionally, as fruit-eaters, they act as seed dispersers.

Both species of orangutan are endangered because of hunting, habitat loss and the sale of babies as pets.

Orangutan Intelligence

 

Orangutans are tool users. They use sticks to extract honey from bees' nests and termites and ants from tree holes. They use leaves and sticks to help themselves handle prickly fruit.

An orangutan will make an umbrella out of big leaves to keep away the sun or the rain.

Before an orangutan crosses a stream, it will use a stick to test the depth of the water.

When water is scarce, an orangutan will chew holes in a leaf and then use the chewed-up leaf to soak up water in holes in trees.

Orangutans use objects to produce sounds. They making kissing noises to call to one another, placing leaves against their mouths for amplification.

When males make territorial warning calls, they slam small trees and tree limbs to the ground, creating loud crashing noises.

In captivity, orangutans have been taught to use keys, hammers, screwdrivers and saws.

Orangutans pass knowledge on from generation. Orangutans have culture; with different groups or orangutans using tools in ways that are specific to that group (culture).

Like all great apes, orangutans are self aware. They recognize themselves in mirrors.

Orangutans possess theory of mind - they understand that others perceive things in ways that differ from how they perceive them.

For example, if a human hides food in front of an orangutan, then later, another human comes into the orangutan's enclosure, the orangutan will direct the second human to the food. The orangutan knows that even though it knows where the food is, the human does not know the location of the food.

Orangutan Language

Between 1978 and 1986, Lyn Miles, a doctor of anthropology at the University of Tennessee at Chattanooga, taught American Sign Language to an orangutan named Chantek.

By the end of that time, Chantek had mastered about 150 signs.

Dr. Robert Shumaker has taught orangutans at the Smithsonian National Zoo and the Great Ape Trust to communicate using a symbol-based language.  The symbols used in this language are abstract and do not resemble the objects they represent.