Great Orange Apes
Orangutans are a special type of primate called a great ape. Orangutans, sometimes just called orangs, are the largest arborealmammals and are quite intelligent. They have orange-brown fur, large heads, and sturdy bodies. They have long arms, short bowed legs, and no tails. Their hands are similar to human hands with four long fingers and a thumb. Orangutans walk on legs and arms but are able to stand and walk short distances on two legs. Orangutans live in the tropical rainforests of Asia. One species of orangutan lives on the island of Borneo. The other species lives on Sumatra. Both orangutan species are endangered.
Orangutans live in the tropical rainforests of Borneo and Sumatra. They spend most of their time in the trees. They even sleep in them.©G.Ellis/GLOBIO.org
Hanging Out in the Forests
The name orang utan means “old man [or person] of the forest.”Endangered orangutans live in a few isolated tropical rainforests with a lush growth of dipterocarp and other tropical trees. Hot temperatures, daily rains, and humid conditions characterize these tropical rainforests throughout much of the year. There are between 12,000-15,000 Bornean orangutans and fewer than 3,500 of the much rarer Sumatran orangutans.
A Body Built for the Treetops
Orangutans have a very specialized anatomy. Special adaptationslink them to the rainforest and a life in the treetops.
Click on the orangutan below to discover more.
An Orangutan is Born
Female orangutans give birth between 230 and 260 days after mating. Although females may give birth to two young, twins are extremely rare. When a baby orangutan is born, it cannot do anything for itself. It cannot walk and needs the care and protection of its mother to survive. Orangutan babies may stay with their mothers for up to eight years before striking out on their own. In her lifetime, a female orangutan may successfully raise only two or three babies.
Baby orangutans learn many important lessons from their mothers. Mother orangutans teach their babies where to find food, how to climb, and how to build a nest for sleeping.©G.Ellis/GLOBIO.org
Bonding with Mom
In the rainforest, orangutan young rarely see each other. Most young orangutans grow up with only the company of their mother. The mother teaches the baby everything it needs to know about surviving in the tropical rainforest. A mother helps her baby learn which trees have the best leaves or fruit to eat. She also teaches it which areas of the forest to avoid.
A Nest in Which to Rest
One important lesson a mother teaches is nest building. Once in the afternoon and once at night, an orangutan will build a nest in the fork of tree branches high above the ground. The nest is a layer of broken branches that is lined with fresh leaves. It is just big enough for one orangutan.
All Grown Up
Male orangutans are large apes. They are generally more than twice the size of females. Males may weigh around 90 kg. Females rarely reach 40 kg.©G.Ellis/GLOBIO.org
Around the age of eight, a young orangutan begins to move away from its mother and create its own life. It will be another six or seven years before it is fully grown. Adult males are twice the size of females. They weigh up to 90 kg. Females rarely reach 40 kg. A full-grown orangutan may stand as tall as 1.5 m at the shoulder (when on two legs). Female orangutans reach breeding age when they are around 15-years-old. They may continue to reproduce until about age 40. Orangutans live up to 60 years.
Snacking All Day Long
An orang’s digestive system is more similar to that of a carnivorethan an herbivore. For this reason, much of what an orangutan eats is passed as poop. To make up for its inefficient digestion, an orangutan needs to consume a large amount of food - up to 12 kg of fruit, leaves, and bark each day - to get all its nutrients. To obtain this much food, an orang must spend 6-8 hours a day foraging and eating.
Fruit is the First Choice
Fruit is the orangutans’ favorite food. But they eat different parts of a plant depending on the time of year. In the dry season, they eat a diet of bark and tropical fruits like jackfruit, durian, and figs. They will also eat birds’ eggs, insects, and small lizards.
Leaves and Bamboo Will Also Do
During the rainy season, orangutans munch mostly on the leaves and new shoots of bamboo. In captivity, orangutans are fed mostly fruits and leafy plants like lettuce.
Hooting and Hollering
Adult orangutans are generally solitary, but they communicate using hoots and hollers. Males communicate with a special vocalizationcalled a “long call” (click the audio button to hear them). The long call can last up to two minutes and starts with a series of roars. Each roar gets louder until the last begins fading away like bubbling water. The long call is probably used to warn other males and to signal females during mating season.
Orangutans and People
In Borneo, people and orangutans have been living together for thousands of years. The relationship between orangutans and people has changed dramatically over the past 100 years. The tropical rainforests are under increasing pressure from loggers, farmers, and large agriculture companies. As people use more and more land, less is left as wild tropical rainforest, which orangutans must have to survive. Poaching of orangutans for the illegal pet trade is another serious problem.
Do Not Pet
The illegal pet trade in orangutans and many other types of wildlife is, unfortunately, very common in Indonesia and throughout Southeast Asia. Every year, hundreds of adult female orangutans are killed. Their babies are sold into the illegal pet trade. Many baby orangs die before they become pets. Stress and disease kills as many as four out of five young orangs in the first few months after being caught.
A Return to the Wild
Orangutans that are confiscated from the illegal pet trade are sent to rehabilitation centers. Staff members at the centers feed and care for them. The goal is to eventually release them back into their forest homes.©G.Ellis/GLOBIO.org
Indonesian and Malaysian laws exist to protect endangered wildlife species. Often the enforcement of these laws is very difficult. In order for law enforcement officials to be able to confiscate illegally held orangutans, they must first find them. Then they must have a place to bring them where they will be protected.
These protective places are calledrehabilitation centers. Sepilok Orangutan Rehabilitation Center and Wanariset Orangutan Rehabilitation Center are two rehabilitation centers in Borneo. They are critical to the survival of orangutans and the returning of confiscated orangs back to the wild.
Disappearing Tropical Rainforests: A Disaster for Orangutans
Orangutans are losing more of their tropical rainforest home each year. Habitat loss due to deforestation is one of the greatest threats. Tropical rainforests are cut for wood and to create farms such as palm oil tree plantations. On Sumatra the forests and orangutans are disappearing faster than those in Borneo, but both species are in great danger of extinction.
Stranded on Lonely “Islands”
The most damaging development has been dividing the orangutans’ habitat into little patches of forest, like little islands. Today, many orangs are isolated in these small islands of forest. They cannot connect with one another to mate and have babies. Their naturally slow breeding rate adds to the problem. It makes it harder for them to recover from poaching, habitat loss, and other human-related causes of death.
Saving the Orangutan...and the Tropical Rainforests
Orangutans spend their time in the lush, tropical dipterocarp forests. The forest has everything an orangutan needs including food, water, and lots of space to climb.©G.Ellis/GLOBIO.org
People are working to protect the orangutans and the tropical rainforests. The nations of Indonesia and Malaysia have set up five officially designated areas for protecting and rehabilitating orangutans. All areas are in the lowland tropical rainforests of Sumatra and Borneo. Another way to help save the forests and the orangutans is with ecotourism. Instead of cutting the forests, people take visitors on hikes in the forests.
The rainforests of Borneo and Sumatra are some of the oldest in the world. They are more than 80 million years old. They are home not only to the orangutan but to other rare mammals, exotic birds, insects, and plants. The orangutan is an umbrella species.Protecting the orangutans protects the habitat for many other wildlife and plant species that are critical to the biodiversity of the tropical rainforest.