Great Blue Heron at Good Harbor Beach ~ Click to view larger
There are several theories as to why birds, especially large wading birds such as herons and flamingoes, stand on one leg, or “unipedal resting” as scientist like to refer to the trait. The seemingly most convincing and best-proved theory is that birds stand on one leg to conserve body heat. It is shown that birds stand on one leg more often when wading, which again points to the thermoregulation hypothesis because water draws away more body heat.
Great Blue Heron (Ardea herodias)
Standing on one leg is not necessarily a sleeping and resting habit. I have filmed Great Blue Herons and Snowy Egrets meticulously preening while standing on one leg. The characteristic is not limited to large wading birds; species with shorter legs, including ducks and swans, also stand on one leg. Another popular theory suggests that wading birds stand on one leg to look less suspicious to aquatic prey.
Center of gravity and line of gravity
To read more about avian sensory physiology, visit the website of Professor Dr. Reinhold Necker. Additional images courtesy Professor Necker’s website.
Beautiful photos, Kim 😉 All of those are plausible/probably reasons for standing on one leg. Have you done “tree” pose in yoga? It is very restful, and is similiar to the birds’ pose. They may also realize that something in the water could bite that one leg, and keeping the other safe gives a better chance to get away and survive… Happy New Year! WG
Happy New Year to you to WG! Yes, i think of tree pose too when seeing herons and egrets standing on one leg.