A SPRING in the step is the secret to making light work of parenting, at
least if you鈥檙e an Australian wallaby. A female can carry a 鈥渏oey鈥� weighing up
to 15 per cent of its own weight without any additional exertion, according to a
new study.
Russ Baudinette of the University of Adelaide and Andrew Biewener of Harvard
University鈥檚 Concord Field Station measured the forces on tendons in the
animals鈥� leg muscles as they hopped. They found the joey-laden mothers only need
an extra bit of energy on the first hop. That energy is stored in their elastic
tendons, giving them a boost on every subsequent jump (Nature, vol 395,
p 653).
Animals with this energy-saving gait probably had a selective advantage, says
Biewener. 鈥淎nd it looks like a fun way to move,鈥� he adds.
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