Orangutans nests reveal their engineering skills

London, Apr 25 (ANI): Orangutans show remarkably advanced engineering skills when making nests, researchers have found.

The researchers, led by scientists at the University of Manchester, followed and filmed the apes in the forests of Sumatra. The team also took orangutans' nests apart to see how they were constructed.

Their study, published in the journal PNAS, reveals that the apes select thick branches for a scaffold and thinner branches for a springy mattress.

All great apes make nests - gorillas, chimpanzees and bonobos, as well as orangutans.

Unlike birds, apes make a new nest each night. They also often construct day nests - perhaps for a nap following a big feed.

Young orangutans often build "practice nests", apparently honing their technique.

Roland Ennos from the University of Manchester, a senior member of the research team, told BBC Nature that the behaviour revealed the animals' "sophisticated tool use and construction skills".

"They show a lot of engineering know-how in how they build their nests," he said.

As anyone who has ever tried to snap a live twig from a tree will know, living, green branches do not snap cleanly in half.

Dr Ennos explained that the animals "made use" of this, bending and weaving large, flexible branches into a strong nest scaffold.

The animals then filled this scaffold with fine, leafy branches - making a comfortable bed.

PhD 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. The animals could complete this task in as little as five or six minutes.

Once the animals woke up and left their nests in the morning, Van Casteren clambered in - some of them were at heights of over 30m - in order to measure them.

"I'd take each nest apart [and] take pieces of it back to our camp to test it," he told BBC Nature.

Mechanical tests revealed, he said, that orangutans were "choosing branches based on their structural properties".

"Male orangutans can weigh up to 80kg and they nest very high up, so these need to be strong structures," Van Casteren said.

He added that studying our primate cousins revealed insight into the origin of our own "representational view of the world".

"Instead of just [seeing] a branch, the orangutans also see a nest-building material," he said.

Prof Richard Byrne from the University of St Andrews said that the evolutionary significance of nest-building in great apes had been "neglected" by researchers, because it was not considered to be advanced tool use.

"Researchers have defined a 'tool' as a detached object used to solve some problem as an extension of the body, and the nests made by apes are not detached - the branches are broken, but still attached to the tree," he explained to BBC Nature.

"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 added. (ANI)