The Suaq Orangutans

The orangutans at Suaq belong to the species of the Sumatran orangutans (Pongo abelii), which are somewhat lighter furred and more gracile than their Bornean relatives (Pongo pygmaeus spp.). Orangutans are, aside from the African great apes, human’s closest relatives: our lineages split only about 9 – 13 million years ago. We humans share around 97% of our DNA with the orangutans, which explains the striking similarities between the two species. Sumatran orangutans are on the IUCN red list of endangered species and classified as critically endangered, which means that they are at the brink of extinction. According to most recent estimations, only around 14’700 Sumatran orangutans remain on this planet.

The Suaq orangutans are special…

Suaq is an exceptional site for orangutan research. The forest of Suaq has the highest orangutan density on earth. On top of that, in terms of their behavior, social structure and in many other ways, the orangutans at Suaq are a truly unique population of Sumatran orangutans:

Picture taken by Caroline Schuppli 2011.
Walter is using a tool to get termites out of a nest, not bothered by the fact that Friska and Fredy are watching him closely. Photo credit: C. Schuppli, January 2011.

… more gregarious than orangutans elsewhere.

Whereas most orangutans live rather solitarily, at Suaq they spend most of their time in small groups. The all year around abundance of fruits reduces feeding competition and allows the Suaq orangutans to be more tolerant towards each other than orangutans at other populations.  At Suaq associations happen voluntarily and even unrelated individuals tolerate each other close by.

Cissy, preparing a tool by peeling and brushing the end of a broken off twig. Photo credit: C. Schuppli February 2017.

… uniquely complex and diverse behavioral repertoires.

Orangutans at Suaq habitually and flexibly use of tools in the foraging context and show many other complex feeding- and nest building techniques. Many of these techniques are only found at Suaq. This pattern of behavioral variation across sites cannot be explained to ecological or genetic difference and thus classifies as cultural variation.