Like most monkeys, Orangutans spend most of their lives swinging from tree to tree eating fruit. But how does a large primate like that do it? It's not surprising that small animals don't need a ton of energy but the larger ones definitely do.
The answer, is a question of energy balance. But where do they get that from? A fruit based diet like the one orangutans prefer won't provide much energy. Dr Lewis Halsey and his team at the University of Roehampton has enlisted some expert practitioners of parkour to simulate orangutan movements in a controlled environment.
According to the researchers, the orangutans' secret is to use the natural moment of the trees to keep their own energy costs down. Their mass allows them to make their tree sway back and forth until its close enough to the next tree to move on. It's not the quickest way to move about, not to mention the safest either, but its energy efficient, and saves about 90% of energy it would take to climb one tree to the next.
Orangutans in Sumatra share their environment with tigers, which means, anytime spent on the trees is time well spent being alive. And they also rely on the fact that the trees are pretty close by to one another. The orangutans can jump, but they can't do it often because of what Dr. Halsey calls their "energetic knife-edge."
That's troublesome, as Dr. Halsey told BBC News, because human expansion into their ecosystem has meant many trees are being cut down:
"They're very large animals and their food intake is quite poor, so everything they do is geared towards being energy efficient. As their environment is affected by humans cutting down trees, they are coming across more gaps and those gaps are bigger and more expensive."
If patches of forest do become too far apart, the orangutans might become stranded in their own little islands of contiguous trees.