Why orangutans spend most of their lives in trees
Researchers used human street athletes as models for orangutans to
measure the energy required to navigate a forest using different
strategies and found it pays to stay up in the trees.
The findings help us to understand why orangutans spend most of their
lives in trees despite being much larger than other tree-dwelling
animals. It also helps to explain how these primates get by on their
diet of mainly fruit, which does not provide a lot of energy.
"Energy expenditure could be a key constraint for orangutans - moving
through trees could be energetically expensive," said Dr Lewis Halsey of
the University of Roehampton, who led the study.
The team found that the most efficient way to cross from one tree to
another is usually to sway back and forth on your tree until you can
reach the next one. When trees are stiff, it is more efficient to jump.
For heavy primates the tree must be quite stiff before jumping becomes
the easier option.According to Halsey: "Heavier orangutans don't jump,
and we may have an explanation why."
To compare the energy required to sway trees, climb trees, or jump
from branch to branch, Halsey's team created obstacle courses simulating
these activities. But instead of orangutans, the participants were
parkour athletes, specially trained street gymnasts with good
flexibility and spatial awareness.
The athletes wore devices that recorded their oxygen consumption as
they proceeded through the activities.
"Because primates are not easy to work with, estimates of energy
expenditure have been very indirect. We have gone a step closer to
understanding these costs by measuring energy expenditure in a model
primate - the parkour athlete," Halsey added.Their work was presented at
the Society for Experimental Biology's meeting in Salzburg, Austria on 2
July 2012. - ANI
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