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Orang-Utans in the Wild
The orang-utan (pongo pygmaeus) is a large red-haired ape with human-like facial features. It is one of the world's largest primates, second in size to the gorilla. The name orang-utan is derived from two Malay words - "orang" meaning "man" and "hutan" meaning forest, hence the term "Man of the Forest."
Orang-utans are almost completely arboreal with bodies that are perfectly suited to life in the trees. They have long arms, a stocky, thick-set body and short legs. Males can attain a height of 150 cm, weigh up to 100 kilograms (220 lbs) and have an arm span of 240 cm when they reach sexual maturity at 13-15 years of age. Mature males also have cheek pads and a throat pouch. Females are smaller, reaching a height of 105 cm and a weight of 40-50 kilograms. They reach sexual maturity at 8 years of age. The average life expectancy of a wild orang-utan is thought to be 35 years whilst in captivity orang utans have been known to live for 50 years.
Orang-utans have a low reproductive rate with females giving birth once every 4-8 years. As they live relatively long lives the orang-utan's breeding pattern is based on producing a small number of well-cared-for young. A perfect case of quality not quantity. The gestation period is 275 days and the female usually produces a single infant, although twins are sometimes born. The young are nursed exclusively by the mother and carried around on her back or at her breast until they are completely weaned at three years old. When the mother gives birth again, the adolescent becomes more independent but may still stay with its mother until it is 7 or 8 years old.
Orang-utans mainly feed on wild fruit such as mango, figs, lychee, durian and jackfruit, and spend most of their day roaming the forest in search of food. They also eat insects such as ants and termites, leaves, eggs, flowers, bark and pith. When moving from tree to tree orang-utans test branches to make sure that they are strong enough to take their weight. As night approaches, they build a sleeping platform of branches and other vegetation. A new 'nest' is usually built every night.
Unlike other apes, orang-utans are largely solitary animals. This social behaviour reflects the fact that each individual requires a large home range to forage for food. Scarcity of fruit in the forest and the limited number of orang-utans a tree can support mean that social groups are not exactly feasible. However, females do sometimes come together in small groups of four or five, especially in the fruit season when food is abundant and therefore not worth fighting over.
The orang-utan is an endangered species and is only found in the rainforests of Malaysian Borneo (Sarawak & Sabah), Indonesian Borneo (West, East & Central Kalimantan) and Northern Sumatra. Although it is difficult to accurately estimate the total population of wild Orang Utan due to the dense forest cover, there are thought to be only 20,000 Orang Utan left in the wild; 6,000-7,000 in Sumatra and the rest in Borneo. Habitat loss due to deforestation and human encroachment, hunting and the illegal pet trade have all contributed to declining numbers. As the number of suitable forest areas is constantly being reduced, orang-utan populations are being forced into relatively small areas which realistically can not support such high population densities.
Although enforcement is sometimes a problem, the orang-utan is totally protected by law in Malaysia and Indonesia. In addition both the Malaysian and Indonesian governments have set up rehabilitation centres and research programmes in order to gain a greater understanding of these intelligent creatures, and also to re-introduce animals into the wild. There are two centres in Malaysia - one at Semengoh in Sarawak and the other at Sepilok in Sabah, which runs the larger and more well known of the Malaysian programmes. Indonesia has centres at Ketambe in Northern Sumatra and Tanjung Puting in Kalimantan. The later is still run by its founder, Dr Birute Galdikas.
Rehabilitation has proved to be controversial and details of success rates are unknown. Animals are usually introduced into areas that are already populated by orang-utans. These areas may will be approaching their carrying capacity. The introduction of strangers into an area where most of the orang-utans know each other is also likely to cause social tensions. Furthermore, although the rehabilitated animals are quarantined there is the question of whether these new animals introduce human disease into the existing wild orang-utan population.
In essence, the only way to ensure the survival of the orang-utan in the wild is to preserve its natural habitat. Thankfully, a number of reserves have been successfully established in Malaysia and Indonesia, most recently the Lanjak-Entimau wildlife sanctuary which spans a large area both sides of the Sarawak-Kalimantan border in Borneo. With the continual loss of habitat in both Sumatra and Borne, the day is fast approaching when the only orang-utans left will be found exclusively in pockets of protected forest areas, zoos and rehabilitation centres. The only hope for survival is if enough national parks and sanctuaries are set-up to safeguard the existence of a number of viable breeding populations. Only then will the continued existence of one of the most fascinating and intelligent creatures on the planet be assured.