Once found throughout Southeast Asia, this species of ape now survives only in small populations across the islands of Borneo and Sumatra.
A dominant male ranges over a large territory, mating with several females. Female orangutans give birth to a single offspring, weighing about 4 lbs, every three to six years. The gestation period for the orangutan is 233 - 265 days. A mother spends up to 8 years rearing the infant, and may have only two or three in a lifetime which means they struggle to repopulate as numbers decline.
The male orangutan grows to around 5ft tall and can weigh up to 230 pounds. Females however only reach half that size. Orangutans reach maturity at 7 - 10 years of age and can live up to 40 years in the wild.
The orangutan is almost completely arboreal (tree-dwelling), which is why it is found in the lowland forests of Borneo and Sumatra. They have no tails and cannot jump. They navigate round the canopy by climbing and swinging from tree to tree this is known as 'brachiation'.
They are highly intelligent animals and possess great strength, their strong hands and feet, which can grip like hands, are supremely adapted to life in the trees. Using their long arms, which span between 7 and 8ft across, they gracefully swing through the forest canopy.
These apes make a fresh nest in the crown of a tree every night and rarely come to the ground to drink – instead drinking the water that collects in tree holes.
Orangutans are mainly vegetarian, but occasionally will eat insects. By the age of 10, orangutans have learned to identify more than 200 different food plants. These food plants range from durians, wild figs and mangoes to leaves, twigs and honey.
Orangutans must eat vast quantities of these foods to survive and will spend over half their day searching for sustenance. They know the location of many different fruit trees in the forest, a skill passed onto them by their mothers, and when each tree is due to bear fruit, which in some cases is only every two or three years. Research has linked the El Nino effect to the fruiting cycles of the rainforest trees. The loss of the rainforest also contributes to global warming and changes the weather systems, causing droughts and floods.
So why do they need help?
Just ten years ago the estimated population was around 27,000, today it could be as low as 15,000.
Indonesia and Malaysia were once covered in forest, until 40 years ago when wood became a more valuable commodity. The clearings made perfect farm land and overzealous agriculture fast cleared the orangutans’ natural habitat.
In an attempt to improve the local economy, many global development banks fund palm oil plantations. Unfortunately, these plantations strip the land bare of its lowland forest. For example, a plantation can grow to be well over 300,000 hectares in size.
Almost unique to Borneo is the dipterocarp rainforest. Dipterocarp being the Latin name given to describe the two-winged seeds of the fruit of the trees that make up the forest.
When wind blows a ripe seed off a dipterocarp, the wing acts like the blades of a helicopter, allowing the seed to float at a distance from the parent tree and begin a life of its own. In these forests the trees can reach heights of more than 200 ft.
Man’s activities have forced orangutans into much higher elevation forests, which are not as fertile and cannot support the same biodiversity as the lowland forests.
In addition, orangutans need large areas of forest to survive as they are solitary creatures. Males are very territorial and live alone except when mating and will travel over long distances to find a mate.
As well as sharing 96.4% of human genes, these gentle creatures can also catch most of the diseases that affect humans including tuberculosis, pneumonia and polio.
The United Nations has officially recognised the plight of these great apes and has launched The Great Apes Survival Project. Despite this, the orangutan is considered to be critically endangered.