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How Orangutans Make (Comfy) Beds

An orangutan peeks out of her nest in the Sumatran forest. (All photos by Adam van Casteren)

You climb high up into the trees, where the view is just stunning, and select the perfect spot for a hammock.

Then, expertly, you pull branches across each other, half-breaking them so they stay attached to the trunk but can be woven together as bed springs. Then you tear off smaller, leafy branches and weave them together for your mattress, and then line the hammock with comfy leaves.

All in all, it’s taken you about 10 minutes, and then you just climb in for a good night’s sleep. (Orangutans sleep for about 14 hours.)And that’s your nightly routine if you’re an orangutan in the forests of Indonesia. Your beds are perfectly engineered. And they don’t even need laundering. After all, since you’ll likely have found a new place to hang out tomorrow night, you can just make a new bed wherever you are.

A team of researchers worked in the forest for a year, following some of the orangutans and studying nests that had been abandoned. They discovered that these great apes construct large, oval nests in the canopy, up to 5 feet long and 3 feet wide, and capable of supporting large males, who can weigh up to 250 pounds, or a mother and child.

A typical orangutan nest being measured by the researchers

The orangs choose strong, rigid branches for the structural parts, and weaker, more pliable branches for the lining. The branches chosen for the framework are cleverly snapped halfway across so they remain firmly attached to the tree. Sometimes they also create a roof made of big leaves to protect them from the rain.

Sometimes, while they’re out on a day hike through the forest and they’ve just had lunch, they’ll build a quick day bed for an afternoon nap.

The scientists involved in the study were especially interested in the fact that the talent for building nests is more than just instinctive. Young orangs learn from their parents, and they go on to develop more inventive nests. Biologist Dr. Roland Ennos, of Manchester University, said orangutans possess clear engineering expertise. He said the same applies to birds, too:

“Through field observations, recent research into the woven nests of African weaver birds has demonstrated that, although there may be evidence for a genetic element of nest building, there is also evidence for improved constructions and construction behavior through nest-building experience.

“This suggests that nest building in birds and primates both require a degree of cognitive ability, but certainly no less than that needed for tool construction and use.

“The importance of nest building should not therefore be overlooked when investigating the evolution of intelligence; its cognitive and technical requirements may be comparable to that of tool use, and continued research into nest building highlights the technical abilities of great apes and other animal architects.”

Ph.D. student Adam van Casteren, who led the research, spent a year in northern Sumatra following and studying orangutans. He and his colleague, Julia Myatt from London’s Royal Veterinary College, filmed the orangutans as they built their daily nests, and brought some of the abandoned beds down to the ground for study. The nests can be hard to spot high up in the canopy, but the two researchers found 14 of them.

“We’d take each nest apart and take pieces back to our camp to test,” he told the BBC.

An orangutan in the forest of Borneo

Prof. Richard Byrne, of the University of St Andrews, who studies animal behavior, said that nest-building has tended to be neglected by researchers, because it hasn’t been recognized as advanced tool use.

“But it may be the cognitive skills of nest building that really underpin the abilities that in humans –  and to a much more limited extent, in chimpanzees – allow sophisticated tool manufacture,” he said.

Altogether, orangutans have an impressive amount of technical knowledge about their construction materials. And while other great apes – chimpanzees, gorillas and humans – create beds, orangutans appear to be the most skilled in creating sturdy and elaborate bedding.

Van Casteren says there are questions yet to be answered, like how and why do orangutans choose the trees they prefer for their nests? They tend to avoid the most common species.

But there’s not much time to answer these questions. The forests that are home to the orangutans are being demolished to make way for palm oil plantations, and the orangs are rapidly going extinct.

As for researching the benefits of sleeping 90 feet up in the canopy, van Casteren admitted he hadn’t tried it himself. “I was worried about falling out mid-dream,” he said.

The study is reported in the journal PNAS, under the title Nest-building orangutans demonstrate engineering know-how to produce safe, comfortable beds.