The first thing that comes to mind when anyone mentions "flamingos" would most likely be an image of the huge bird in its signature one-legged stance.
As much as the graceful pose impressed people, however, it also intrigued scientists who sought out how and why flamingos naturally choose to balance on one leg even when sleeping.
There have been several theories and possible explanation with regard to the flamingos' one-legged pose, but it isn't until now that researchers found evidence in the bird's own anatomical structure. What researchers found was that flamingos have an automatic locking system in their joints that allow them to become more stable by standing on one leg.
Theories Disproved
As mentioned above, there have been several theories attempting to explain the flamingos' natural behavior of striking its signature pose when sleeping. Some scientists suggest that alternating the use of one leg allows flamingos to rest their fatigued leg, while others believe it's the bird's way to retain body heat since only one leg is submerged in cold water at a time.
A study by Georgia Tech's Young-Hui Chang and Emory University's Lena Ting disproved both theories after closely observing juvenile flamingos and examining cadavers to find some sort of locking mechanism in their joints, which was also disproved.
Discovering The Flamingo's Secret
Chang and Ting used force plates, a sensitive device that measures small bodily movements when standing, to record the movement of eight juvenile flamingos during their waking and sleeping hours. What they found was that the juvenile flamingos' bodies swayed less when they were perched on one leg as they sleep, as opposed to when they are awake.
The force plates also revealed that the flamingos standing on one leg when asleep were more balanced than those that are awake and doing minimal activities like grooming.
"And that's the opposite of what we would expect for you or me — if I was standing on one leg and then closed my eyes, typically I would see a great increase in the amount of body sway and usually that results in people having to put their foot down," Ting said.
The researchers also acquired and dissected flamingo cadavers to find a locking mechanism in the birds' joints, which they theorized was responsible for its stability, but Chang and Ting found that flamingo joints did not lock at all, regardless of its angle and position.
When Chang picked up the cadaver on its ankle and turned it upright, however, the cadaver suddenly went into the same one-legged stance we all know.
According to the researchers, the bird's body folds forward a bit when they take this stance, which moves its center of gravity into a position that gives more stability.
"What we showed is that when they go to sleep their bodies can sort of flap forward due to gravity, and then the whole thing just collapses and becomes very stable," Ting notes.
Watch the video of the researchers testing the flamingo cadaver's stability while in its signature pose below.
 
Of course, we know that animals are smart and have the tendency to do things in simpler ways, even if that means manipulating humans and other animals. Ting also suggests that — more than the automatic mechanism in flamingos — the birds may actually prefer the one-legged stance because it is easier.
The study titled "Mechanical evidence that flamingos can support their body on one leg with little active muscular force" was published in the Royal Society's Biology Letters journal.
