The Red Apes — Sumatran and Bornean Orang-utans

The orangutans are the two exclusively Asian species of extant great apes — both are Critically Endangered.

Native to Indonesia and Malaysia, orangutans are currently found in only the rainforests of Borneo and Sumatra — as of July 2016 both are now listed as Critically Endangered. Orangutans are the most arboreal of the great apes and spend most of their time in trees. Their hair is typically reddish-brown. Males and females differ in size and appearance. Dominant adult males have distinctive cheek pads and produce long calls that attract females and intimidate rivals. Younger males do not have these characteristics and resemble adult females. Orangutans are the most solitary of the great apes, with social bonds occurring primarily between mothers and their dependent offspring, who stay together for the first two years. Fruit is the most important component of an orangutan’s diet; however, the apes will also eat vegetation, bark, honey, insects and even bird eggs. They can live over 30 years in both the wild and captivity.

Sumatran Orang-utan

The Sumatran orangutan is one of the two species of orangutans. Found only on the island of Sumatra in Indonesia, it is rarer than the Bornean orangutan. The critically endangered Sumatran orang-utan has been the victim of poaching and young into the wildlife trafficking trade. Overall habitat loss through deforestation driven by industrial agriculture — primarily palm oil plantations and paper pulp.

There has been an estimated decline of over 80% over the last 75 years (assuming a generation length of at least 25 years; Wich et al. in press). This decline continues, as forests within its range are under major threat. Most orangutans are outside of protected areas, including within potential logging areas and conversion forests.

Bornean Orang-utan

Bornean orangutans (Pongo pygmaeus) are currently found on the Southeast Asian island of Borneo and generally inhabits swampy and hilly tropical rainforests. Bornean orangutans have a patchy distribution throughout the island and is completely absent from the southeast region. Fossil evidence suggests that Bornean orangutans were once widespread throughout Southeast Asia and evenly distributed across the entire island of Borneo. Due to illegal logging and the destruction and conversion of tropical forest to agricultural land this once expansive range has decreased dramatically.

More About Sumatran Orang-utans and Bornean Orang-utans


Content via Museum of Zoology/ University of Michigan

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