One compelling reason for travelling to Malaysia is to see orangutans in their natural habitat. These iconic primates have intriguing characteristics and a fascinating lifestyle, as Rebecca Gibson reveals in her facts about orangutans.
Orangutans are the largest arboreal (tree-dwelling) mammal on the planet. They are split into three species: Bornean, Sumatran and Tapanuli. The latter lives on the island of Sumatra and was only classed as separate from the Sumatran species as late as 2017. The differences are not highly obvious. Tapanuli Orangutans have smaller skulls than the other species and make calls that last around 20 seconds longer than those of Bornean Orangutans. In scientific terms, these characteristics of orangutans are sufficient information to set one species apart from another, even if the ordinary observer would be hard-pressed to identify them.
Photo Credit: Orangutan’s limbs are adapted to live in the trees, Shutterstock
Physical Features of Orangutans
The orangutan name is Malay for ‘person of the forest’. That is an apt description as they are highly adapted for life in the trees. In fact, orangutans spend about 95% of their time off the ground. Their bodies have distinct features that set them apart from other great apes. Fossils and DNA studies suggest they split from the hominids family (gorillas, chimps, bonobos and humans) 14 million years ago. They have long limbs, with an arm span of over 2m in males. Their feet are shaped like hands so they can grip branches with them. Flexible hips also help them to move easily through the forest canopy.
Orangutan’s shaggy orange fur varies from auburn to ginger in shade. Why they are that colour is the subject of debate. Some say light reflecting from muddy pools gives everything in the forest a dappled reddish glow to match the animals. Others that amongst the mix of living and dead leaves in the canopy the apes’ coloration blends in.
Male orangutans are much larger than females, the latter being about 25cm (10in) shorter and half the weight on average. When all species of orangutans are fully mature, at about 35 years, some but not all adult males develop flanges. These make the orangutan’s face look flat and take the form of flaps of fatty tissue from their foreheads to their chins. They may not look like the sexiest facial features you’ve ever seen, but you’re not an orangutan.
It’s thought that female orangs take the quality of the males’ flanges into account when choosing a mate. Unflanged males are smaller than flanged ones but they are still sexually mature. They can father offspring but they are not usually the ones chosen by the females. There is a hypothesis that a flanged male somehow stunts the development of potential rivals. This process is called bimaturism and may have something to do with the smell of particular hormones the dominant male exudes. However, this aspect of the apes’ development is not yet well understood.
Male orangutans with facial flanges have another distinctive upper body feature. Large throat sacs under their chins that come when they develop the flanges. They use these as echo chambers to make what is referred to as Long Calls. This loud vocalisation is used to warn off other males and to locate females.
Photo credit: Borneo Nature Tours. Male orangutans develop cheek flanges as they mature.
Orangutan Habitat and Diet Information
Orangutans are typically found in low-lying peat swamp forests below 500m in altitude. Where they roam in those forests depends on the availability of the 300 kinds of fruit they eat. Their diet is varied, although one of their preferred fruits is the Durian. This large knobbly fruit has a smell similar to sewage or rotting flesh but that doesn’t put off a hungry primate! Despite its smell, this member of the mallow family is highly nutritious.
Orangutans seem to hold a mental map of the fruit trees in their home forest and their fruiting times. This means they don’t waste precious energy hunting for ripe fruit randomly. Fruit seeds pass through an orangutan’s gut without being broken down. This makes the animals very effective seed dispersers and therefore important members of the rainforest ecosystem. When fruit is not available, orangutans have to eat less nutritious leaves, flowers or bark. They also consume insects. Their foraging habits help more light reach the forest floor as they snap off branches and create gaps in the tree canopy.
Photo credit: Borneo Eco Tours, Robert Christian. Young orangutans learn the facts they need to survive from their mothers. Males take no part in their upbringing.
Facts About an Orangutan’s Interesting Behaviour
Similar to other great apes, orangutans are intelligent animals and often use tools when feeding. Sticks help them pick termites and ants out of holes and they occasionally construct a ‘glove’ out of leaves for handling prickly food. Orangutans make nests in the trees to sleep, and they construct a new one every night. They have also been seen creating makeshift umbrellas by using large leaves to cover their heads. And they build a roof of foliage over their nest on a wet night.
When hasn’t been much rainfall and water is in short supply they will chew up leaves to make them absorbent. This leafy mush is then poked into pools in tree holes and the water sucked out of it.
Competition for food has led to orangutans evolving to live mostly solitary lives, unlike many other primates. They cannot be said to be friendly but they have gentle natures and don’t generally pose a threat to anyone. Males take no part in raising their offspring, which are only born every eight years. This is the longest gap between births of any land-based mammal (except humans). It means a female orangutan will rarely give birth more than three times in her life.
Photo credit: An artist’s impression of ideal orangutan rainforest, Tabin Wildlife Resort
Threats to Orangutan’s Survival
An assessment was made by the International Union for Conservation of Nature (IUCN) in 2016. Its facts about orangutans revealed there may only be around 100,000 Bornean, 14,000 Sumatran and just 800 Tapanuli left in the wild. They were once widely distributed across Asia but now cover just 5% of their original range.
Huge areas of the orangutan’s rainforest habitat are being cut down to create palm oil plantations. But it’s believed that the biggest threat to these animals is from illegal killing. An orangutan nest count study published in the journal Current Biology in 2018 recorded an estimated decline of 148,500 orangutans from 1999 to 2015. This was mostly as a result of poaching on top of deforestation. Only slightly more than half of the populations in the study area contained at least 100 individuals. This number is sadly the lowest possible for viable breeding to take place.
Tapanuli orangutans live in the Batang Toru Ecosystem, North Sumatra. At around 1,000 square kilometres, this is an area smaller than London or Los Angeles. Plans there to build a hydroelectric dam – affecting approximately 8% of the region – would fragment orangutan habitat even further. It would also increase the risk of inbreeding caused by a lack of access to unrelated animals in other areas.
Photo Credit: Borneo Nature Tours, rainforest scene with canopy walkway.
Efforts in Orangutan Conservation
The vast majority of orangutans (80%) are situated outside of protected areas, which is unfortunate for the survival of their species. The Sepilok Orangutan Rehabilitation Centre in Sabah has around 60 to 80 rescued orangs living within the boundaries of the Centre, which is on the edge of the Kabili Sepilok Forest Reserve. They take in orphaned young orangutans as well as ones confiscated from the illegal wildlife trade. Younger apes that lost their mothers early are paired with older ones. In this way they learn the skills they need to survive away from the Centre in the wider forest area.
A UK-based charity, Orangutan Appeal UK, dedicated to supporting orangutans, raising awareness and funding projects across Malaysia and Indonesian Borneo, offers a young orangutan adoption programme for adults and children. It also gives information on its website of the latest releases into the wild of rehabilitated orangutans at the Sepilok Rehabilitation Centre.
The Orangutan Information Centre (OIC) was set up in 2001 in Sumatra’s Leuser Ecosystem to try to raise awareness of the primates. The OIC takes in 20-30 orangutans each year – on many occasions these individuals have come into conflict with local farmers. Although the rescued animals are released back into the wild, it’s thought that their mortality rate can be as high as 80%. To combat conflict with humans, the people who live alongside orangutans need to be provided with alternative livelihoods. This includes paying them not to fell trees. The Sumatran Orangutan Society monitors the forest and if it’s intact, they pay the local villagers.
There are also other conservation projects in Borneo. The Borneo Orangutan Survival (BOS) Foundation – based in Central and East Kalimantan – is currently caring for over 600 orangutans. A nursery has been set up for orphans under two years old and BOS Foundation workers take on the role of surrogate mothers. They take care of their needs and encourage the babies to learn to climb and explore. At the next stage, named Forest School, care givers teach the young orangutans to make nests and forage for food. After Forest School, the orangutans are moved to pre-release islands. There they’re monitored for up to two years to determine when they’re ready to face life in the wild. Following a final medical examination, the release candidates are taken to their new homes.
Photo Credit: Shutterstock, Orangutan resting, safe in a sanctuary.
Facts About Releasing Orangutans Back Into the Wild
The facts are that finding a place to release orangutans can be a challenge with so much suitable habitat threatened. Luckily, the BOS Foundation has secured the rights to release in three different areas throughout Kalimantan. Local people are hired to help monitor the progress of rewilded orangutans and communities are involved in their protection. In February 2021, the BOS Foundation made headlines when it released 10 orangutans back into the wild. These were five males, two females and a mother with two babies.
The BOS Foundation is responsible for an area that supports one of the largest remaining wild populations of orangutans in the world. The Mawas Conservation Forest is around the size of Yosemite National Park in the US. It spans 309,000 hectares of peat swamp forest and is an essential carbon reservoir. The area doesn’t just support orangutans and other rainforest wildlife but the entire planet. Without these peat forests trapping and storing carbon, climate change would be an even greater threat.
Would You Like to See Orangutans in Their Native Habitat?
Tour operators on Blue Sky Wildlife are local experts who can arrange a trip to Malaysia to see orangutans, learn more facts about them and information on conservation efforts to stem their declines.
Rebecca Gibson is a wildlife writer based in the UK. She is currently studying for an MA in Travel and Nature Writing at Bath Spa University and uses her blog to share her writing and photography and raise awareness of British wildlife.
Original Date of Publish : 10 April 2021