One Leg Up

Well, it certainly is one of the most frequent questions we get from guests at the Zoo: “Excuse me, but why do flamingos sometimes stand on just one leg?” This is very reasonable question and, for our entire careers, Zoo staff have always had to admit that we just do not know—regardless of all the unfounded speculations out there. Our colleagues at Emory University and Georgia Tech have finally put forward a very strong case to answer that question. Equally exciting is the fact that the Chilean flamingos at Zoo Atlanta were crucial participants in the study!

The answer is deceptively simple, and quite satisfying. By positioning the single leg centrally under the body, they can balance absolutely still for extended periods of time (sleeping, for example) and exert essentially zero energy. They made this point very clear by demonstrating that a dead flamingo can be balanced on one of its legs and remain upright for hours. [Note: the dead flamingos were not from Zoo Atlanta.]

While a dead flamingo cannot be balanced upright on both of its legs. This approach was rather brilliant, I think, because clearly a dead flamingo cannot exert any energy in its muscles, so the only conclusion that can be reached is that single-leg standing requires no energy and double-leg standing requires at least some energy. The team observed and filmed the living flamingos at Zoo Atlanta and demonstrated that flamingos using two legs sway a bit, with swaying being an indication of instability caused by alternately using and resting the leg muscles. Flamingos on single legs were essentially motionless, indicated complete stability as a result of no muscle action.

Taken altogether, the authors have shown that flamingos stand on one leg because they can do so without exerting, or wasting, any of their precious metabolic energy. Amazing stuff, really. Now, I beg the question: “Are there right-legged and left-legged flamingos?”

Publication: Chang, Y.H., and L. H. Ting. 2017. Mechanical evidence that flamingos can support their body on one leg with little active muscle force.
Biology Letters 2017 DOI: 10.1098/rsbl.2016.094

Joe Mendelson, PhD
Director of Research