Almost all birds stand on one leg. Some can even sleep while standing on one leg. Why do they do it and why don’t they fall over?

Long-legged birds, such as storks and flamingos, often stand on one leg, but so do short-legged birds, such as ducks.

Birds generally don’t have feathers on their legs. Standing on one leg reduces heat loss. Birds tuck one leg under their feathered body to keep it warm, leaving only one leg exposed.

Studies at the Dormund Zoo in Germany show that flamingos stand on one leg more often in cooler temperatures of below 20 Celsius (68F). This reduces heat loss by half. Some scientists theorize that it may prevent muscle fatigue, but there is no evidence of this.

When humans stand on one leg, they must concentrate to maintain balance – and they can’t sleep while standing on one leg. But it’s not a balancing act for birds, because they have an in-built stabilizer.

Birds have in-built stabilizers in two ways: (1) stabilizing joints, and (2) an equilibrium sense organ.

Birds have special hip joints and inter-tarsal joints (foot joints) to stabilize their body. There also seems to be an equilibrium sense organ in the lumbosacral vertebral canal – the lower part of the backbone (spine) – that helps to keep balance.

Birds also have a different centre of gravity than humans. Birds have a centre of gravity (COG) in their lower body near their legs, whereas humans have their COG in the mid-pelvic region. When birds are standing on two legs, they bend their knees slightly to maintain balance. On one leg, the standing leg is directly below the centre of gravity.

Photographer: Martina Nicolls

Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM