ORANGUTAN FACTS
Did you know, orangutan means ‘person of the forest’ in Malay dialect?
WHERE DO ORANGUTANS LIVE?
Orangutans are now only found on the two islands of Borneo and Sumatra.
Fossil evidence suggests that during the Pleistocene era, from around 1.8 million years to 11,500 years ago, orangutans lived throughout much of Southeast Asia, from Java in the south, up into Laos and southern China.
The preferred habitat of orangutans is low-lying peat swamp forest.
the three species of orangutan
There are three species of orangutan, the Bornean orangutan (Pongo pygmaeus), the Sumatran orangutan (Pongo abelii) and the Tapanuli orangutan (Pongo tapanuliensis).
Bornean orangutans can be distinguished by their larger size, darker red hair, and wider faces. Sumatran and Tapanuli orangutans look more alike, with longer, brighter orange hair and slighter builds.
Orangutan adaptationS
Orangutans the largest arboreal animals in the world. This means they spend almost their entire lives in trees.
They are perfectly adapted to this lifestyle with long, strong arms, flexible hips, and hand-like feet to help them grip branches as they move through the trees.
THE DIET OF ORANGUTANS
Orangutans are predominantly frugivorous (fruit-eating), but are known to consume a wide range of foods from over 400 different species.
Orangutans are known as the ‘gardeners of the forest’ due to their crucial role in maintaining the health of their forest habitat. As they move through the canopy, they create gaps that allow light to reach the forest floor below, while the seeds they disperse help the forest regenerate.
Intelligence and tool-use
Like all great apes, orangutans have large brains and are self-aware beings capable of reasoning. Wild orangutans use tools such as sticks to extract insects to eat.
Every night, orangutans construct a new nest to sleep in, intricately woven out of branches. They are the only ape that use leaves as an umbrella during rainfall.
Captive or semi-wild orangutans have been taught to use sign-language, demonstrating their vast capacity for learning and understanding. Local lore says that orangutans can speak but choose not to for fear of being put to work.
HOW MANY ORANGUTANS ARE THERE?
Being arboreal, orangutan population numbers can be difficult to estimate. Numbers are estimated by counting nests built in the treetops.
According to the most recent Population and Habitat Viability Assessment (PHVA) in 2016, there are an estimated 57,000 Bornean orangutans, 13,000 Sumatran orangutans and 800 Tapanuli orangutans left in the wild. Approximately 80% of these orangutans are living outside of protected areas.
Social behaviour
Unusually among primates, orangutans have evolved to be semi-solitary. This is most likely due to competition for food, as trees don’t bear enough fruit to support groups.
The only time you will see orangutans together in the wild are as a family unit, consisting of a mother and her infant(s), or as a pair of orangutans engaged in courtship.
Courtship lasts 3 to 10 days. The male plays no part in the upbringing of offspring.
Orangutan life stages
Orangutans are the slowest breeding of all primates. On average, they give birth every 7 to 8 years - the longest interbirth interval of any land mammal.
The reason for this long interval is that infant orangutans have so much to learn, from the map of the forest, to where to find food, and which foods are safe to eat. Being solitary, the mother and infant form a very special bond during this time - one of the closest in the animal kingdom.
Wild orangutans will normally have no more than 3 to 4 offspring in their lifetime. Their slow reproduction rate and long childhoods makes orangutan populations highly vulnerable to extinction.
THREATS TO ORANGUTANS
Over 30% of Borneo’s forests have been lost in the past 40 years, making habitat loss the greatest threat to orangutans. All three species of orangutan are now listed as Critically Endangered. If current trends continue, it has been projected that the Bornean orangutan could lose 70-80% of its remaining forest habitat by 2080.
CLIMATE CHANGE
Climate change poses a growing threat to orangutans and their forest habitat. Rising temperatures and changing rainfall patterns can disrupt forest fruiting cycles, affecting the availability of the food orangutans depend on.
Borneo’s forests also store vast amounts of carbon. When these forests are destroyed or degraded, this carbon is released into the atmosphere, further accelerating climate change.
Oil-palm plantations
Indonesia is the world’s largest producer of palm oil, a vegetable oil extracted from the fruit of oil-palm trees. The expansion of oil-palm plantations has contributed to extensive forest loss in Borneo, reducing and fragmenting vital orangutan habitat.
Sustainable palm oil production can help reduce this impact, particularly when plantations are developed on previously degraded land rather than through the clearance of primary forest.
LOGGING
Well-managed logging concessions can sustain significant orangutan populations. However, illegal and unsustainable logging can severely degrade and fragment orangutan habitat.
Mining
In recent years, mining has caused extensive damage to Indonesia’s forests. Illegal open-cast mining for coal, iron ore and nickel causing significant habitat destruction. Mercury, which is used in some mining processes, contaminates river systems, killing fish and other wildlife.
Forest Fires
Fires is traditionally used to clear land for agriculture (slash-and-burn), but during particularly dry conditions, fires can spread out of control and cause widespread forest fires. This risk higher during El Niño events, which can bring prolonged dry conditions to Indonesia.
Peat forests are particularly vulnerable, as once ignited, their highly-flammable organic material can burn for long periods and be extremely difficult to extinguish.
Human-Wildlife Conflict
As human populations expand into forest areas, orangutans and people are increasingly brought into closer contact, increasing the potential for conflict.
Orangutans are protected under Indonesian law, making it illegal to capture, harm, kill or trade them. However, conflict can still occur when orangutans enter farms or plantations in search of food.
Finding ways for people and orangutans to coexist is therefore essential. Many communities surrounding the forest depend on its natural resources for their livelihoods, and so sustainable forest management and human-wildlife conflict mitigation is vital for both people and wildlife.
Learn more about our work with local communities to reduce harmful agricultural practises and human-wildlife conflict.
ORANGUTANS AND CLIMATE CHANGE
Due to their capacity to absorb carbon dioxide, standing forests are one of the natural world’s greatest carbon-capture systems. Peat swamp forests in particular, store vast amounts of carbon in their carbon-rich soils. The protection of these tropical forests, and the orangutans that ensure their regeneration, is critical for stabilising global climate patterns.
TEACHING RESOURCES
These resources contain information and activities answer your questions about orangutans and our work to protect their future. If you have any enquiries about these resources, please contact us.
