One prior explanation for why flamingos stood on one leg was that they conserve energy by putting one leg in the cool water where they feed. Another explanation was that such a stance reduced muscle fatigue. Until now, researchers had not directly explored how much muscle activity the birds needed to balance on one leg.
But, in a recent study, researchers used eight young flamingos after they had eaten and were getting sleepy to measure their posture and postural sway by capturing the force applied to the ground. In measurements taken by scientists, flamingos had very little postural sway as they were falling asleep. But “when they were awake, and grooming or jousting with their buddies, while standing on one leg, their speed of the postural sway increased up to seven times.” (Ting, 2017). This indicates that “Flamingos can stand on one leg for a really long time . . . and may not even need to use their muscles for the task.” (Klein, 2017). While standing on one leg, the flamingos appeared to use some kind of “passive strategies that relied less on muscles and nerves and more on simple mechanics of how their bodies fit together.” (Ting, 2017).
Joanna Klein, May 2017, The Science Behind the Flamingo’s One-Legged Stance. The New York Times.
Lena Ting, May 2017, Neuromechanics of Flamingos’ Amazing Feats of Balance, Scientfic American.