The orang utan (pongo pygmaeus) is found in the rainforests of Malaysian Borneo (Sarawak and Sabah), Indonesian Borneo (Kalimantan) and North Sumatra. It is one of the world’s largest primates, and is almost completely arboreal (tree living). The word “orang” is Malay for “person” whilst “utan” is derived from “hutan” meaning forest. Thus, orang utan literally translates as “person of the forest”.
A mature male has large check pads and a pendulous throat sac. Adult males can reach a height of 150 cm (5 ft), weigh up to 100 kg (220lbs) and have an arm span of 240 cm (8 ft). Females are about three quarters of the height and half the weight of the males. Both sexes are covered with long reddish hair. Orang utan have a low reproductive rate, females usually giving birth to a single infant once every 7-8 years. Females reach sexual maturity at 12 years of age but generally don’t have their first offspring until two or three years later. Males reach sexual maturity at 15 but their cheek pads may not fully develop until a few years later. The life expectancy of orang utan in the wild is unknown but is thought to be less than in captivity, where some have lived to over 50 years of age.
Orang utan are primarily fruit eaters and spend most of the day roaming the forest foraging for food. They are particularly fond of wild figs and the pungent smelling durian. Although fruit is their most important source of food, they also feed on young leaves, insects, bark, flowers, eggs and small lizards. Each individual builds a new nest each night, a safe resting place 12-18 metres (40-60 ft) up in the roof of the forest.
Wild orang utan are generally solitary. However, adolescents often gather in pairs and females occasionally form temporary groups of four or five. This rather lonely existence stems both from the relative scarcity of food in the rainforest and from a lack of predators. A mature adult roams a vast area of forest every day in order to find enough food to satisfy its healthy appetite. Its huge size also eliminates the need for ‘group defence’.
The orang utan is an endangered species and is totally protected by law in Malaysia, Indonesia and internationally. Today, there are an estimated 20-27,000 orang utan left in the wild (perhaps 20,000 or so in Borneo and the rest in Sumatra). Deforestation, human encroachment on their habitat, indiscriminate hunting and the live animal trade: all are factors that have contributed to a decline in their numbers. To gain a better understanding of the orang utan and re-introduce rescued animals into the wild, both the Indonesian and Malaysian authorities have set up rehabilitation programmes. Sarawak’s centre at Semenggoh is open to the public so visitors can find out more about these highly intelligent creatures of the rainforest.
