The brilliant pink flamingo is often seen while standing on one leg. Although being heavily hypothesized, it has remained unclear, why they do this. Recent research by scientists from Saint Joseph’s University in Philadelphia may explain why.
Matthew Anderson and his team observed a captive flock of flamingos at the Philadephia Zoo. For all animals they noted if they were standing on the land or in the water, if they were standing on one of two legs and on what leg they were standing. They found that although the birds could flee faster when standing on two legs, they stand on one leg more often when in water compared to when being on land. Furthermore they revealed that compared to when it was warmer, in cooler wheather more birds favored standing on one leg.
Although it may seem logical that these tropical birds may not need to worry about losing body heat, they spend most of their time in the water which causes them to lose body heat more rapidly. The researchers therefore concluded that thermoregulation is a key reason behind the flamingo stance.
I would argue another possibility flamingos stand on one leg more often in the water than on land is because on land there is a higher chance of predation. To test this it might be interesting to see if in the large flocks of flamingos especially the birds on the outside stand more on two legs compared to the birds in the center of the group, since the outer most birds may have a higher change of being caught.
Furthermore, thermoregulation may indeed be an important reason behind the characteristic pose since water is a much better heat conductor compared to air. However, it may be be not as important as the authors suggest since the waters in which the flamingos stand are typically shallow and heat quickly. This could be easily tested with water from different temperatures. Since the behaviour of standing on one leg can be seen in many species of birds, among which many are non aquatic, it appears to be part of a more general energy conservation strategy.
It thus seems that thermoregulation might indeed play an important role in the one-legged pose of the flamingo, but the question why they do it remains only partly explained.
What do you think? Leave your suggestion in the comments!
Anderson, M. J. and Williams, S. A. (2010), Why do flamingos stand on one leg?. Zoo Biology, 29: 365–374. doi: 10.1002/zoo.20266