The Real Reason Why Flamingos Stand on One Leg

A pink flamingo gets some shut-eye while standing on one leg. Patrick Rolands/Shutterstock

There are plenty of good reasons why flamingos are so famous. Their pink plumage is hard to ignore, of course, but so are those stilt-like legs and the birds' propensity for standing on one leg while tucking themselves into a ball to sleep.

Why do they choose to use a single leg when resting? Is it to regulate body temperature or to rest their muscles? This has been a bit of a mystery — until now.

Atlanta-based researchers Young-Hui Chang from the Georgia Institute of Technology and Lena Ting of Emory University experimented with live and dead flamingos to figure out the physical mechanism used by the birds to stand on one leg. It turns out, even dead birds can be made to stand on one leg without any support, meaning there's no energy required to pull off the trick.

"[A] team from the U.S. has shown that flamingos employ no active muscular effort when they're unipedal, meaning they are also expending less energy," reports the BBC. "A passive mechanism is engaged in the one-legged position, allowing flamingos to stand proud while having a doze."

The researchers call it a "passive gravitational stay mechanism." Standing on one leg requires less energy than standing on two. It all boils down to minimizing energy when resting, and flamingos have evolved to become real pros at the single-leg stance.

However, exactly why they evolved this ability to rest so efficiently remains unclear. The researchers want to understand the exact physical mechanisms that allow the birds to perform the trick, and that will help to uncover more of the story behind this unusual sleeping preference.