Orangutan translates to “person of the forest” in the Malay language; an apt description for a mammal that shares approximately 97% of our DNA. And just like humans, orangutans have distinct “vocal personalities” that are shaped through their socialization with others.
In a 2022 study published by Nature Ecology and Evolution, scientists recorded thousands of hours of “kiss-squeak” calls from 70 wild orangutans across six different social groups living in Borneo and Sumatra over a period of five years. The data revealed that dense orangutan populations have greater diversity and experimentation in their vocabulary, while smaller, low-density communities use a slang repertoire that they constantly revisit.
“Many more clues await us in the lives of our closest living relatives, as long as we manage to guarantee their protection and their preservation in the wild,” says Adriano Lameira, first author of the paper. “Each disappearing population will take with it unretrievable glimpses of the evolutionary history of our species.”
Disappearing Populations
Unfortunately, the disappearance of orangutans is a very real threat. The Bornean orangutan (Pongo pygmaeus) population is now estimated at roughly 104,700; the Sumatran (Pongo abelii) at about 14,613; and a third species was announced in 2017. With no more than 800 individuals in existence, the Tapanuli orangutan (Pongo tapanuliensi) is the most endangered.
In addition to losing one of Earth’s great apes, Asia’s island ecosystems would lose much of their health and biodiversity. If orangutans disappear, so will several tree species, especially those with larger seeds. Orangutans are frugivores, and their diet comprises a variety of 500 plant species. They delight in lychees, mangosteens and figs and slurp water from holes in trees. As tropical “gardeners,” they play a vital role in the dispersal of seeds throughout lowland forests, river valleys and floodplains. This lush mosaic landscape also provides local communities with water for drinking, cooking, bathing, irrigation and hydroelectricity.
Land converted to agriculture and deforestation for the timber trade threaten critical orangutan habitat. An estimated 300 million trees have been cut down since 1994 in Borneo alone. Orangutans are the largest arboreal mammal and spend the majority of their lives in trees. With their long, powerful arms and grasping hands and feet, they swiftly swing through a maze of branches and seek refuge under the canopies. Using a combination of vegetation and brush, they construct nests to sleep at night and rest during the day.
Orangutans exhibit a fission-fusion social system and tend to organize in loose female communities with floating males. With the exception of mother-infant pairings, there are no permanent social groups. These great apes are particularly susceptible to extinction because of their reproductive fitness. Rates are low due to slow sexual maturity, single offspring and long intervals between births. An infant is born once every 3-5 years, so the species can take a long time to recover from population declines.
Tapanuli Orangutan
On November 20, 2013, an injured orangutan was found in the mountainous region of Tapanuli. The Sumatran Orangutan Conservation Program (SOCP) treated his wounds and even extracted air rifle pellets from his body. The veterinary team and accompanying researchers named him Raya and hoped he would recover soon. Despite their best efforts, Raya succumbed to his injuries a mere eight days later. Cause of death? Torment and harassment at the hands of humans.
Though Raya met a tragic end, he went on to become the representative member of a new species: Pongo tapanuliensis—also known as the rarest great ape on the planet. When researchers examined his skull, they observed noticeably different characteristics in comparison to orangutans from other regions.
This discovery prompted the largest genomic study of wild orangutans at the time. Nater et al. analyzed 37 orangutan genomes and concluded that based on morphological, behavioral and environmental data, the isolated population of the Sumatran orangutan south of Lake Toba, Batang Toru, was highly distinct from the northern Sumatran and Bornean populations. The findings were published in November 2017 in the journal Current Biology and quickly garnered the attention of scientist Sean Sloan, who fiercely advocated for the protection of P. tapanuliensis.
The Batang Toru forest is one of the most biodiverse locations in Indonesia, home to critically endangered species like Sumatran rhinoceroses and the Sunda pangolin. However, anthropogenic encroachment is fragmenting and degrading the Tapanuli orangutan’s range. World Wildlife Fund Asian Species Expert Dr. Barney Long declares: “Hunted, sold, pushed out of their forest homes—the plight of one of man’s closest living relatives is of our making and yet we can help them recover.”
Deforestation & Habitat Loss
Orangutan population and distribution have declined rapidly since the middle of the 20th century, due to road construction, agricultural conversion, mining, logging, hunting and energy infrastructure development. Habitat in north Sumatra is primarily destroyed by the conversion of forests to oil palm plantations and widespread forest fires. The fires destroy vast areas of orangutan habitat, and thousands of these apes have perished in the flames.
In Borneo, nearly 80% of the remaining orangutan population survives outside of protected conservation areas. Numbers here have declined by more than 50% over the past 60 years, and the species’ habitat has been reduced by at least 55% over the past 20 years. “The fate of Sumatran orangutans is inextricably linked to the islands’ fast-disappearing forests. If we want to save the Sumatran orangutan, we have to save their forest home,” Dr. Long pleas.
Hunting & Illegal Wildlife Trade
Rampant poaching, facilitated by the growing number of roads and logging trails, poses a grave threat to Borneo’s orangutans, tigers and rhinos. The Sumatran orangutan is among the 283 species currently recognized under the IUCN SSC Asian Species Action Partnership, but despite legal protection in Indonesia, orangutans are still captured from the wild and imprisoned in households as exotic pets and status symbols. Studies have indicated that 200-500 orangutans from Borneo alone enter the pet trade each year.
In some areas, orangutans are hunted for food and the bushmeat trade. A single orangutan is worth several hundred dollars in city markets. There is also demand for orangutan parts in Kalimantan, Indonesia, with their skulls fetching up to $70. Experts estimate that even as little as 1% of females lost each year through hunting or other unnatural causes could put a population on an irreversible trajectory to extinction.
WWF works closely with TRAFFIC, the wildlife trade monitoring network, to help governments enforce the laws that prohibit orangutan capture and trade. This work includes strengthening the capacity of rangers, prosecutors and customs officers to identify, investigate and prosecute wildlife crimes. They assist in rescuing orangutans from traders and from people who keep them illegally as pets. Many rescued orangutans are taken to refuges where they can recover and be rehabilitated and then are eventually released back into the wild in places such as Bukit Tigapuluh National Park.
Human-Orangutan Conflict
When orangutans can’t find food, they will sometimes venture into oil palm plantations, resulting in death by retaliation. Palm oil coming from Borneo and Sumatra accounts for more than half of all palm oil produced in the world. WWF co-founded the Roundtable on Sustainable Palm Oil in 2003, a collaborative group working to bring sustainable palm oil to the marketplace and reform land use practices.
WWF partners with governments, plantation owners and local communities like Borneo’s Dayak people to ensure that agricultural areas are developed as far away from orangutan habitat as possible. In 2010, WWF developed a creative program known as, Panda CLICK! (Communication Learning toward Innovative Change and Knowledge). The initiative encouraged community members to capture photos and videos of their surroundings—images they felt were significant to their culture—and through this visual documentation, transfer knowledge to younger generations.
WWF also encourages ecotourism, which generates financial support for orangutan conservation, brings economic benefits to those living nearby and increases the commitment of residents to protect the animals.
Discover Borneo’s Wild Side with Nat Hab & WWF
Join Natural Habitat Adventures in Borneo, the world’s third-largest island, and observe wild orangutans share vines with leaf monkeys, wild gibbons, flying lemurs and rare proboscis monkeys in the tallest and most ancient rain forests on Earth. Learn about crucial efforts to conserve them at two rehabilitation centers!
The Semenggoh Orangutan Center was founded in 1975 and has cared for more than 1,000 animals. Its rehabilitation mission has been so successful that the surrounding reserve has now reached its carrying capacity. Semenggoh now focuses on the study of orangutan biology and behavior while providing a natural haven for dozens of apes that are graduates of the program. The center is also home to numerous babies, born in the wild to rehabilitated mothers—a further testament to the program’s success.
In the Kabili-Sepilok Forest Reserve, we make two visits to the Sepilok Orangutan Rehabilitation Center. Staff teach the babies basic survival skills like finding food, building nests and climbing trees. The center also aids adults that have sustained injuries or require medical care before being returned to their natural habitat. Since the center was established in 1964, more than 100 orangutans have been successfully released. During our visit, we’ll see orangutans up close, learn about the rehabilitation process and hike on boardwalks through the rainforest as we watch youngsters play and receive their daily fruit and milk.
