Why flamingos do have one leg to stand on
The long-standing question of why, and how, flamingos balance on just one leg seems to be about minimising muscular effort, according to a new study from the US.
Young-Hui Chang, from Georgia Institute of Technology, and Lena Ting, from Emory University, used two dead animals donated by a local zoo, to study the mechanics of the bird's posture.
Surprisingly, even in death, the one-legged pose can readily be maintained and is in fact more stable than trying to stand the birds up on two legs, the duo explain in a paper detailing their studies in the journal Biology Letters.
The pair also stood 8 living juvenile flamingos on pressure plates and compared their movements when they were awake and while they were asleep. The birds swayed seven times less while they slept.
The findings suggest that the one-legged pose can be maintained passively, with very little energy input from the bird, although Ting and Chang don't yet know precisely how the bird's anatomy enables it to do this.
The knee and hip appears to incorporate some sort of "stay apparatus" which enables the forces trying to move the joints to be balanced and locked so that the leg remains in position, with the foot beneath the centre of the body, but without burning energy to maintain the position.
The research could, the pair say, explain why many birds - other than just flamingos - similarly adopt a one-legged pose.
More practically, understanding the mechanics of the system could lead to improved prosthetic designs for human amputees and also more energy-efficient robotics.