<p>These orphaned Bornean orangutans, <i>Pongo pygmaeus</i>, cuddle at the Sepilok Reserve in Sabah, Borneo, which is part of Malaysia. The <a href="http://www.orangutan-appeal.org.uk/about-us/sepilok-rehabilitation-centre">Sepilok Orangutan Rehabilitation Centre</a> was founded in 1964 to help such orphans.</p>

Cuddle Time

These orphaned Bornean orangutans, Pongo pygmaeus, cuddle at the Sepilok Reserve in Sabah, Borneo, which is part of Malaysia. The Sepilok Orangutan Rehabilitation Centre was founded in 1964 to help such orphans.

Photograph by Frans Lanting, Nat Geo Image Collection

10 of Our Favorite Orangutan Pictures

On International Orangutan Day, we take a look at these lovable tree-dwelling apes, whose numbers are plummeting fast due to deforestation.

Solitary and intelligent, the orangutan is the only great ape native to Asia—but it's possible the continent may soon have none.

That's because orangutan numbers are dwindling as the animals are driven from their habitats by deforestation for palm oil plantations. The island of Borneo (map) may house only 54,000 of the endangered animal, and on Sumatra (map), just 6,600 remain, according to WWF. That's a drop from possibly 230,000 of the primates a century ago.

But there's one bright spot for this fiery-furred ape: Many companies have committed to only using palm oil from areas that weren't destroyed by logging.

Two species of orangutan—whose name comes from the Malay word for "person of the forest"—swing from the trees in Sumatra and Borneo: The Sumatran orangutan, Pongo abelii, and the Bornean orangutan, Pongo pygmaeus. (Also see "Pictures: Saving Sumatra's Orangutans.")

In honor of International Orangutan Day on August 19, we took a closer look at these lovable tree dwellers.

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