“Chimpanzees, gorillas, and orangutans have been living for hundreds of thousands of years in their forest, living fantastic lives, never overpopulating, never destroying the forest. I would say that they have been in a way more successful than us as far as being in harmony with the environment.”
-Jane Goodall
International Orangutan Day has been set for August 19th, EVERY YEAR! This event is to help encourage the public to take action to preserve this amazing species.
In Malay, the word orangutan means “man of the forest”. Orangutans live lonely lives in the lowland forests where they are found. They drink water from tree holes and eat wild fruits like figs, mangosteens and lychees. They build their nests in vegetation-covered trees so they can rest during the day and sleep at night. Male adult orangutans have a maximum weight of 200 pounds. Male flanged animals have protruding cheek pads called flanges and a throat sac that is utilized for powerful vocalizations known as long calls. A male without flanges appears like an adult female. An unflanged male can become a flanged male for unknown biological causes, a behaviour peculiar to monks. The conservation status of this animal is Critically Endangered.
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Infraorder: Simiiformes
Family: Hominidae
Subfamily: Ponginae
Genus: Pongoeys
There are two main species that can be seen among orangutans, which are called Pongo abelii (Sumatran orangutan) and Pongo pygmaeus (Bornean orangutan).
Bornean and Sumatran orangutans differ a little in appearance and behaviour. While both have shaggy, reddish fur, Sumatran orangutans have longer facial hair. Sumatran orangutans are reported to have closer social bonds than their Bornean cousins. Bornean orangutans are more likely to descend from the trees to move around on the ground. Both species have experienced sharp population declines. A century ago there were probably more than 230,000 orangutans in total, but the Bornean orangutan is now estimated at about 104,700 based on an updated geographic range (Endangered) and the Sumatran about 7,500 (Critically Endangered). A third species of orangutan was announced in November 2017. With no more than 800 individuals in existence, the Tapanuli orangutan is the most endangered of all great apes.
Orangutans’ arms are well suited to their lifestyle because they spend much of their time (some 90 percent) in the trees of their tropical rainforest home. They even sleep aloft in nests of leafy branches. They use large leaves as umbrellas and shelters to protect themselves from the common rains. These intelligent primates search for food in the sunshine. In addition to young leaves, bark, flowers, honey, insects, vines, and the interior shoots of plants, mature fruit is the main food source for orangutans. The fruit of the durian tree is one of their favourite delicacies; it tastes like a sweet, cheesy, garlicky custard and has an overpowering fragrance. Maybe because of its peculiar taste, potent aroma, and enormous size, durian is renowned as the “king of fruits” when it comes to fruits that are grown. Though they also visit gardens owned by people, orangutans consume wild durians in the forest. Acting as important seed dispersers for this fruit as well as many others, orangutans discard the peel, consume the flesh, and spit out the seeds.
Although they are a semi-solitary species, orangutans nevertheless exhibit some degree of social interaction. Out of all the age/sex divisions of orangutans, flanged adult males are the most lonesome. Typically, their involvement in social organizations is restricted to brief “consortships” of a sexual nature with adult and teenage girls. The dads of wild orangutans are not directly involved in raising their young. Adult females who are not responsive tend to socialize with other adult females, and their own offspring, and generally shun older males. While spending time with other orangutans is limited, the bond between a mother and her small child endures for many years. Male subadults typically socialize with females, especially teenagers, but they don’t normally act aggressively against other men. Adolescent females travel in groups, particularly when there are not many age disparities. This semi-solitary social system may have evolved as a result of a ripe fruit diet, scattered food distribution, and a lack of large arboreal predators.
One of the main drivers of orangutan adaptation is competition for access to sexually receptive females. Adult males with flanges utilize their pendulous laryngeal sacs as a resonating chamber for their “long call,” which has roar-like portions. An extended call’s loudness can occasionally be heard for over a mile. Long calls made by male orangutans appear to be crucial in discouraging potential mates and signalling their availability to females who are open to sexual activity. Male adult orangutans are intolerant of one another, and when two flanged adult males come into contact, the outcome is typically avoidance or aggressiveness. When two cheek-padded males are near a sexually receptive female, conflicts nearly invariably result. These fights could go on for a few minutes, an hour, or more. During these battles, men may sustain serious injuries. This causes almost all male flanges to show signs of injury, including as missing or stiff fingers or toes, healed scars on their cheeks or heads, or even missing eyes. Since orangutan females do not often display the kind of extreme aggression observed in combat, they do not suffer from these kinds of wounds.
In the past, orangutans were located on the island of Java and in southern Sumatra, and they roamed all over Southeast Asia and even into southern China. These days, the only places where orangutans may be found are the islands of Borneo and Sumatra, with the Sumatran variety restricted to the island’s north. There are nine distinct populations of Sumatran orangutans, all of which are found in the Indonesian provinces of Aceh and North Sumatra. Bornean orangutans are located in Kalimantan, Sabah, and Sarawak, and they are far more widely dispersed. There are no documented permanent orangutan populations in Brunei. Mostly found at elevations of less than 1,000 meters (3,281 feet) above sea level, peat swamp forests, tropical heath forests, and mixed dipterocarp woods are home to orangutans on both islands. A positive correlation has been seen between the density of orangutans and the availability of fruit. In other words, orangutans are found to reside at significantly larger densities than in other woods in areas with higher fruit supply and fewer or less severe seasonal fruit shortages. Sumatran orangutan populations are generally denser than Bornean orangutan numbers because Sumatran forests
appear to be more productive than Bornean forests. Compared to other types of wood, orangutans inhabit peat swamp forests at densities higher.
The conservation of orangutans is vital due to their critically endangered status, primarily threatened by habitat loss, poaching, and illegal wildlife trade. Key strategies include protecting and restoring their habitats in Southeast Asia, preventing deforestation, and establishing protected areas. Promoting sustainable practices, strengthening anti-poaching laws, and supporting rehabilitation centres for orphaned orangutans are crucial. Additionally, scientific research and community education are important for fostering stewardship and awareness. Effective conservation requires collaboration among governments, NGOs, and local communities, emphasizing a multifaceted approach to ensure the survival of orangutans for future generations.
Finally, orangutans are remarkable primates known for their intelligence, social complexity, and unique adaptations to life in the trees of Southeast Asia’s rainforests. As critically endangered species, they face significant threats from habitat loss, poaching, and the illegal wildlife trade. Conservation efforts are crucial to protecting these incredible animals and their habitats, ensuring that future generations can appreciate their role in biodiversity and the health of our planet’s ecosystems.
Written by:
Hashani Navodya
2nd Year Undergraduate
Biological Science
Faculty of Science
University of Colombo
References
Chua, L., Harrison, M. E., Fair, H., Milne, S., Palmer, A., Rubis, J., … & Meijaard, E. (2020). Conservation and the social sciences: Beyond critique and co‐optation. A case study from orangutan conservation. People and Nature, 2(1), 42-60.
Knott, C. D. (1999). Orangutan behavior and ecology. The nonhuman primates, 5, 50-57.
Galdikas, B. M. (1988). Orangutan diet, range, and activity at Tanjung Puting, Central Borneo. International Journal of Primatology, 9, 1-35.
Nater, A., Mattle-Greminger, M. P., Nurcahyo, A., Nowak, M. G., De Manuel, M., Desai, T., … & Krützen, M. (2017). Morphometric, behavioral, and genomic evidence for a new orangutan species. Current Biology, 27(22), 3487-3498.
Husson, S. J., Wich, S. A., Marshall, A. J., Dennis, R. D., Ancrenaz, M., Brassey, R., … & Singleton, I. (2009). Orangutan distribution, density, abundance and impacts of disturbance. Orangutans: Geographic variation in behavioral ecology and conservation, 77-96.
Image Courtesy
- 1st content image : https://www.worldwildlife.org/photos/orangutan_279107
- 2nd content image : https://images.app.goo.gl/QzE7LzxN2gctL5vA7
- 3rd content image : https://images.app.goo.gl/oHSFPqFsNMJ9C73T8
- 4th content image : https://orangutan.com/wp-content/uploads/2021/01/Tapanuli-Orangutan1.png
- 5th content image : https://images.app.goo.gl/FBQQCt45yWv9YSo86
- 6th content image : https://orangutan.org/wp-content/uploads/2012/12/orgdist2.gif
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