Orangutans are a species of great ape found only in South East Asia on the islands of Borneo and Sumatra, although evidence of their existence has been found in Java, Vietnam and China. The gentle red ape demonstrates significant intelligence, with an ability to reason and think and is one of our closest relatives, sharing 97% of the same DNA as humans. Indigenous peoples of Indonesia and Malaysia call this ape Orang Hutan literally translating into English as People of the Forest.
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| A female orangutan called Baboon in Orangutan Island |
The name of the genus, Pongo, comes from a 16th century account by Andrew Battell, an English sailor held prisoner by the Portuguese in Angola, which describes two anthropoid “monsters” named Pongo and Engeco. It is now believed that he was describing gorillas, but in the late 18th century it was believed that all great apes were orangutans; hence Lacapade’s use of Pongo for the genus.
In times past people would not kill them because they felt the orangutan was simply a person hiding in the trees, trying to avoid having to go to work or become a slave.
Orangutans are unique in the ape world. There are four kinds of great apes: gorillas, chimpanzees, bonobos and orangutans. Only the orangutan comes from Asia; the others all come from Africa. There are two separate species of orangutan – the Sumatran orangutan (Pongo abelii) and the Bornean orangutan (Pongo pygmaeus). Orangutans are only found on the islands of Sumatra and Borneo.
The orangutan is the only strictly arboreal ape and is actually the largest tree living mammal in the world. The rest of the apes do climb and build sleeping nests in the trees, but are primarily terrestrial (spending their lives on the ground). Every night they fashion nests, in which they sleep, from branches and foliage. They are more solitary than the other apes, with males and females generally coming together only to mate. Even the hair colour of the orangutan, a bright reddish brown, is unique in the ape world.
Behavior of Orangutans
Like the other great apes, orangutans are remarkably intelligent. Although tool use among chimpanzees was documented by Jane Goodall in the 1960s, it was not until the mid-1990s that one population of orangutans was found to use feeding tools regularly. For example, when water is difficult to get, they chew leaves to make a sponge to soak up water in tree cavities. When it rains very hard the orangutan makes an umbrella for himself out of big leaves.
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| Using a stick to get the fruit |
According to recent research by Harvard University psychologist, James Lee, orangutans are the world’s most intelligent animal other than man, with higher learning and problem solving ability than chimpanzees, which were previously considered to have greater abilities. A study of orangutans by Carel van Schaik, a Dutch primatologist at Duke University, found them capable of tasks well beyond chimpanzees abilities such as using leaves to make rain hats and leakproof roofs over their sleeping nests. He also found that, in some food-rich areas, the creatures had developed a complex culture in which adults would teach youngsters how to make tools and find food.
Although orangutans are generally passive, aggression toward other orangutans is very common and can be territorial. Immature males will try to mate with any female, and may succeed in forcibly copulating with her if she is also immature and not strong enough to fend him off. Mature females easily fend off their immature suitors, preferring to mate with a mature male.
The orangutan is graceful and agile while climbing through the trees but walking on the ground is somewhat slow and awkward. That is why the orangutan is at a great disadvantage on the ground, and why the orangutan rarely comes down from the treetops. Their food is there, their home is there and they are safer there.
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| Teaching orangutan to climb |
Biology
An orangutan’s lifespan is about 35-40 years in the wild, and sometimes into the 50’s in captivity. They reach puberty at about 8 years of age, but a female isn’t ready for her own baby until she’s in her teens.
The orangutan has the longest childhood dependence on the mother of any animal in the world, because there is so much for a young orangutan to learn in order to survive. The babies nurse until they are about six years of age. The young males may stay close by their mothers for a few more years but the females may stay until they are into their teens, allowing them to observe mothering skills as they watch their younger sibling being raised by the mother.
Orangutan females only give birth about once every 6-11 years – the longest time between births of any mammal on earth. (This results in only 4 to 5 babies in her lifetime.) This is why orangutan populations are very slow to recover from disturbance.
The male's throat sac is used to make a very notable and recognizable call that echoes through the forest. This is called the Long Call and is used to locate and advertise their presence to females or warn other males away.Males often weigh over 200 pounds, where females are 1/3 to 1/2 their size.
The males generally remain solitary until they encounter a female who is receptive to mating. They will stay with the female for several days to ensure a successful mating but will soon resume their solitary life. Due to their large size, males will more often travel on the ground than females. Food is often scarce in the rain forest and that is why the orangutan is a semi-solitary creature. In times of great abundance of food, orangutans may use the opportunity to socialize and gather in small groups.
Ecology, Habitat and Distribution
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| The nest of the orangutan |
Fruit eater sleeps in new nest every night
Imagine sleeping 2 storeys and above up in the trees every night. The arboreal orang-utan lives up in trees where they bend twigs and small branches together to make a large nest-platform for sleeping. They are the largest tree dwelling mammal in the world. Adult orang-utans are solitary, except during mating. Orang-utans are not territorial, maintaining a loose relationship in a given area although adult males are hostile to one another. Crowding may cause them to fight over the limited supply of fruits.
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| Playing with a piece of wood |
Diet
Omnivorous, orang-utans eat both plants and animals but feed mainly on fruits, young leaves, bark and insects. By about the age of ten, an orang-utan can recognise over 200 different plant foods. The orang-utan’s favourite food is fruit, especially durian.
Communication
The first orangutan language study program, directed by Dr. Francine Neago, was listed by Encyclopædia Britannica in 1988. The Orangutan language project at the Smithsonian National Zoo in Washington, D.C., uses a computer system originally developed at UCLA by Neago in conjunction with IBM. Zoo Atlanta has a touch screen computer where their two Sumatran Orangutans play games. Scientists hope that the data they collect from this will help researchers learn about socializing patterns, such as whether they mimic others or learn behavior from trial and error, and hope the data can point to new conservation strategies.
A 2008 study of two orangutans at the Leipzig Zoo showed that orangutans are the first non-human species documented to use 'calculated reciprocity' which involves weighing the costs and benefits of gift exchanges and keeping track of these over time.
Although orangutans are generally passive, aggression toward other orangutans is very common; they are solitary animals and can be fiercely territorial. Immature males will try to mate with any female, and may succeed in forcibly copulating with her if she is also immature and not strong enough to fend him off. Mature females easily fend off their immature suitors, preferring to mate with a mature male. Orangutans do not swim. At least one population at a conservation refuge on Kaja island in Borneo have been photographed wading in deep water.
Orangutans, along with Chimpanzees, gorillas, and other apes, have even shown laughter-like vocalizations in response to physical contact, such as wrestling, play chasing, or tickling.
In Malaysia
Borneo is unique in that it has three distinct populations or subspecies of orang-utans:
• Pongo pygmaeus pygmaeus (northwest populations)
• Pongo pygmaeus morio (northeast and east populations)
• Pongo pygmaeus wurmbii (southwest populations)
Orang-utans in the Malaysian states of Sabah and Sarawak occur mainly in the lowlands. In Sarawak, there are about 1,300 orang-utans, almost all in the Lanjak-Entimau Wildlife Sanctuary and Batang Ai National Park in the south next to West Kalimantan, Indonesia. In Sabah, there were five main areas of special importance with a total of 20,000 orang-utans in the mid 1980s (by WWF-Malaysia working with the Sabah Forestry Department, 1986). By 2004, the orang-utan population in Sabah had dropped to about 11,000 individuals (by Kinabatangan Orang-utan Conservation Project working with Sabah Wildlife Department, 2003). This decline in their numbers in the last twenty years was caused by planned conversion of forests to plantations in the eastern lowlands.
Population decline of 40% in last two decades
Orang-utans in Sabah and Sarawak live mainly in lowland rainforests but are also found in tropical, swamp and mountain forests. Sarawak has about 1,300 orang-utans, almost all in the Lanjak-Entimau Wildlife Sanctuary and Batang Ai National Park to the south bordering West Kalimantan, Indonesia. In Sabah, there are about 11,000 individuals today, the population having declined by over 40% in the last 20 years due mainly to planned conversion of forests to plantations in the eastern lowlands. Drought and forest fires, especially during the El Nino events of 1982-83 and 1997-98, but also 1987 and 1991, contributed to the decline.
Destruction of natural forests and unreliable food sources
Wild orang-utan populations need a reliable source of a variety of fruits and young leaves to survive. They can survive only in extensive natural forests. The availability of food all year round means not all forests can support long-term breeding populations. We now know that this gentle ape can survive only in lowlands - where fertile soils and constant water availability allow steady food production - or where there are several forest types with different fruiting and leaf-producing seasons. There is little point in putting orang-utans where they have historically not existed, as lack of food supply may eventually cause them to die. There are six areas in Malaysia with quite large populations but this does not mean that any one of these places is unimportant. There is always the risk that one or more populations could be devastated by disease, drought or fires.
Maintaining natural forests with viable wild breeding populations and restoring degraded forests is vital for the continued survival of orang-utans in Malaysia. Hence, the Sabah government’s initiative to retain the largest orang-utan population in the Ulu Segama-Malua Forest Reserves under sustainable forest management (SFM) deserves full support. The Deramakot forest management model, which produces controlled amounts of timber for international auction, certified according to international standards since 1997, shows what can be done. SFM could reduce forest damage and provide enough time for the forest to regenerate. In SFM, reforestation is necessary to ensure the forest rehabilitation or restoration take place in any sustainably managed forest. In the Lower Kinabatangan, various isolated forest patches need to be joined through restoration.
Why are orangutans Endangered?
1. Rainforest wildfires
- climate changes - drought which leads to forest fires
- Every 400 000 hectares, 8000 orangutans are killed
2. Deforestation
- The habitat is wrecked.
- Reduces fruit which forms the bulk of orangutans
- Weak ones are unable to survive
- Eventually they die
3. Forest to fields
- Conversion of rainforest lands to agriculture
- Low elevation forests turned into oil palm
- taken overs prime orangutan habitats
- e.g. Eastern lowlands of Sabah, Sampit, Seruyan river
4. Orangutan Poaching
- Forest edges becomes a conflict area between farmers and apes
- The stranded orangutans raid fruits from the farming area and are considered as pests and are shot
by farmers
5. Illegal pets
- Orphans infants are sold in the black market.
- The rescued ones are taught about the skills for living in the wild.
- Once they are free, some cannot adapt to the wildlife, resulting in death.
6. Conservation Laws ignored
- Laws have too little impact. Illegal logging and poaching is unchecked, further endangering them.
