GIBBONS err on the side of caution when swinging between forest branches.
When moving slowly, gibbons always keep one arm on a branch. But as they speed up they let go, taking spectacular leaps between trees. When John Bertram of Florida State University in Tallahassee watched a female gibbon leaping in a lab, he noticed that the ape always overshot her target, then shifted her body at the last instant to compensate.
His analysis has revealed that this takes a little more energy (The Journal of Experimental Biology, vol 206, p 1631). But it pays the animals to overestimate the distance between branches, says Bertram. 鈥淚t鈥檚 catastrophic if they miss,鈥� he says, so a little extra energy is worth it.
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