Sunday, April 17, 2011
A study shows the secrets to how heavy orangutans (up to 180 lbs) travel through the trees to get fruit without breaking branches.
Orangutans sometimes move upright, sometimes horizontally with their limbs fully extended. They avoid repetitive motions, which could make their perches sway more. And they usually grab on to 1+ branch at a time — 1/3rd of time they’re holding more than four at once. Also, climbing higher requires energy and, if the tree is shaking, orangutans must wait for the vibrations. By swaying instead of leaping from branch to branch, orangutans use less energy, and less energy and time if they climbed down and back up trees. Also, adult females swing conservatively while males and youngsters are risk takers.
Chimpanzees, by comparison, pull their bodies close to the tree branch while moving because they are relatively small and don't worry about the vibrations their body weight would create.