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The Orangutans of Indonesia Primates in Sumatra and Kalimantan

The orangutans are two species of great apes known for their intelligence, long arms and reddish-brown hair. Native to Indonesia and Malaysia, they are currently found only in rainforests on the islands of Borneo and Sumatra, though fossils have been found in Java, Vietnam and China. They are the only surviving species in the genus Pongo and the subfamily Ponginae (which also includes the extinct genera Gigantopithecus and Sivapithecus). Their name derives from the Malay and Indonesian phrase orang hutan, meaning “man of the forest”. The orangutan is an official state animal of Sabah in Malaysia.

SUMATRA ORANGUTANS
The Sumatran Orangutan (Pongo abelii) is the rarer of the two species of orangutans. Living and endemic to Sumatra island of Indonesia, they are smaller than the Bornean Orangutan. The Sumatran Orangutan grows to about 4.6 feet tall and 200 pounds in males. Females are smaller, averaging 3 feet and 100 pounds.

Compared to the Bornean Orangutan, the Sumatran Orangutans possess a lighter and longer pelage, a longer face, a smaller stature, and flanges that are covered in small white hairs.

Compared to the Bornean Orangutan, the Sumatran Orangutan tends to be more frugivorous and especially insectivorous.Preferred fruits include figs and jackfruits. It also will eat bird eggs and small vertebrates. The Sumatran Orangutans spend far less time feeding on the inner bark of trees.

Wild Sumatran Orangutans in the Suaq Balimbing swamp have been observed using tools. An orangutan will break off a tree branch that’s about a foot long, snap off the twigs and fray one end. It then will use the stick to dig in tree holes for termites. They’ll also use the stick to poke a bees nest wall, move it around and catch the honey. In addition, orangutans use tools to eat fruit. When the fruit of the Neesia tree ripens, its hard, ridged husk softens until it falls open. Inside are seeds that the orangutans love, but they are surrounded by fiberglass-like hairs that are painful if eaten. A Neesia-eating orangutan will select a five-inch stick, strip off its bark, and then carefully collect the hairs with it. Once the fruit is safe, the ape will eat the seeds using the stick or its fingers. Although similar swamps can be found in Borneo, wild Bornean Orangutans have not been seen using these types of tools.

NHNZ filmed the Sumatran Orangutan for its show Wild Asia: In the Realm of the Red Ape; it showed one of them using a simple tool, a twig, to pry food from difficult places. There is also a sequence of an animal using a large leaf as an umbrella in a tropical rainstorm.

The Sumatran Orangutan is also more arboreal than its Bornean cousin; this could be because of the presence of large predators like the Sumatran Tiger. It moves through the trees by brachiation.

The Sumatran Orangutan is more social than its Bornean counterpart. Groups of these orangutans gather to feed on the mass amount of fruiting on the fig trees. However adult males generally avoid contact with other adult males. Rape is common among orangutans. Sub-adult males will try to mate with any female, though they probably mostly fail to impregnate them since mature females are easily capable of fending them off. Mature females prefer to mate with mature males.

Interval birth rates for Sumatran Orangutan were longer than the Bornean ones and are the longest reported interval birth rates among the great apes. Sumatran orangutans give birth when they are about 15 years old. Infant orangutans will stay close to their mother for up to three years. Even after that, the young will still associate with their mother.

Both orangutan species are likely to live several decades; the longevity estimate can span for more than 50 years, with the oldest captive orangutan, Ah Meng, being born in 1960.[6] Nonja, thought to be the world’s oldest in captivity or the wild at the time of its death, died at the Miami MetroZoo at the age of 55.

The average of the first reproduction of P. abelii is around 12.3 years old with no indication of menopause.

In 2002, the World Conservation Union put the species on the IUCN Red List with critically endangered status. A survey in the Lake Toba forests, found only two habited areas, Bukit Lawang (defined as the animal sanctuary) and Gunung Leuser National Park.The survey estimated only 3,500 orangutans still live on Sumatra in 2002. Baby orangutans are often captured and sold as highly prized pets. In order to catch the babies poachers normally have to kill the mother first to prevent her from protecting her baby.

BORNEO ORANGUTANS
The Bornean Orangutan, Pongo pygmaeus, is a species of orangutan native to the island of Borneo. Together with the slightly smaller Sumatran Orangutan, it belongs to the only genus of great apes native to Asia.

The Bornean Orangutan has a life span of about 35 to 40 years in the wild; in captivity it can live to be 60. A survey of wild orangutans found that males are typically 75 kg (165 lb) and 1.2-1.4 m (4-4.7 ft) long; females averaging 38.5 kg (82 lb) and 1-1.2 m (3.3-4 ft) long

There is evidence that there was gene flow between the geographically isolated Bornean Orangutan populations until recently. The Bornean and Sumatran Orangutan species diverged 1.5 – 1.7 million years ago. This occurred well before the two islands (Borneo and Sumatra) separated. The two species of orangutan are more distantly related than the Common Chimpanzee and the Bonobo. Despite the difference, the two orangutan species were only considered subspecies until as recently as 1996, following sequencing of mtDNA.

The Bornean Orangutan has three subspecies:
* Northwest Bornean Orangutan P. p. pygmaeus – Sarawak (Malaysia) & northern West Kalimantan (Indonesia)
* Central Bornean Orangutan P. p. wurmbii – Southern West Kalimantan & Central Kalimantan (Indonesia)
* Northeast Bornean Orangutan P. p. morio – East Kalimantan (Indonesia) & Sabah (Malaysia)

The population currently listed as P. p. wurmbii may be closer to the Sumatran Orangutan (P. abelii) than the Bornean Orangutan. If confirmed, abelii would be a subspecies of P. wurmbii (Tiedeman, 1808). Regardless, the type locality of pygmaeus has not been established beyond doubts, and may be from the population currently listed as wurmbii (in which case wurmbii would be a junior synonym of pygmaeus, while one of the names currently considered a junior synonym of pygmaeus would take precedence for the taxon in Sarawak and northern West Kalimantan). To further confuse, the name morio, as well as various junior synonyms that have been suggested,[1] have been considered likely to all be junior synonyms of the population listed as pygmaeus in the above, thus leaving the taxon found in East Kalimantan and Sabah unnamed.

The Bornean Orangutan lives in tropical and subtropical moist broadleaf forests in the Bornean lowlands as well as mountainous areas 1500 m in elevation. It lives at different heights in the trees and moves large distances to find trees bearing fruit. Its diet consists of fruit as well as shoots, bark, mineral rich soil and bird eggs. It also eats insects but to a lesser extent than the Sumatran Orangutan.

The Bornean Orangutan travels on the ground more than its Sumatran counterpart. It is theorized this may be in part because there is no need to avoid the large predators which only exist in Sumatra such as the Sumatran Tiger.

The Bornean Orangutan is more solitary than the Sumatran Orangutan. Two or three orangutans that have overlapping territories may interact for small periods of time. Males and females generally come together only to mate. Rape is common among orangutans. Sub-adult males will try to mate with any female, though they probably mostly fail to impregnate them since mature females are easily capable of fending them off. Mature females prefer to mate with mature males.

Newborn orangutans nurse every 3 to 4 hours, and begin to take soft food from their mothers’ lips by 4 months. the first year of its life the baby clings to its mother’s abdomen by entwining its fingers in and gripping her fur. Babies stay with their mothers until they are about 8 or 9 years old and have a long childhood compared to other apes.

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