Orangutans are skilful nestbuilders whose engineering expertise rivals that of birds, say scientistsBy Daily Mail Reporter
The sophisticated nest building skills of Orangutans exhibit a degree of technical knowledge to match those of the most talented birds, say scientists.
The great apes construct large, oval nests in tree canopies where each evening they will curl up and sleep but little is known about their mechanical design.
A year-long study of over a dozen nests on the Indonesian island of Sumatra has now shown the orangutans choose strong, rigid branches for the structural parts that support most of their weight. Females usually weigh about 100lbs but large males can weigh as much as 250lbs.
The study found orangutans use their knowledge of the different ways branches break to erect strong and comfortable nests
And sticks picked for the framework were cleverly snapped halfway across - leaving them attached - whereas those in the lining were completely severed.
The findings published in Proceedings of the National Academy of Sciences suggest orangutans use knowledge of the different ways branches break to erect strong and comfortable nests.
Biologist Dr Roland Ennos, of Manchester University, said - orangutans, like some birds - might possess engineering expertise.
During construction they use the fact branches only break half-way across in 'greenstick' - or incomplete - fractures to weave the main nest structure.
He said: 'They choose thicker branches with greater rigidity and strength to build the main structure in this way.
'They then detach thinner branches by following greenstick fracture with a twisting action to make the lining.
Orangutans construct nests for protection from predators as well as warmth
Nests are built 60 to 90 ft up in the trees and the branches are tested first by swinging on them to ensure they can withstand the weight of them and their offspring for 14 hours of sleep. The orangutan will sometimes use a leaf as a 'roof' to protect itself from the rain.
Dr Ennos said: 'Once weaned, all great apes build nests on an almost daily basis. These structures are constructed, in general, for only one night's use or as a place for rest during the day.'
The word orangutan means 'man of the forest' in the Malay language. As its habitats are being usurped by man, the orangutan's population is decreasing and it is in grave danger of extinction.
Orangutans have a large, bulky body, a thick neck, very long, strong arms, short, bowed legs, and no tail. Orangutans are about 2/3 the size of the gorilla and are mostly covered with long reddish-brown hair.
Previous studies have shown they are very intelligent. As well as using leaves as umbrellas to they also use them as cups to help them drink water.
Dr Ennos said: '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.'
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