Why Does a Flamingo Stand on One Leg?

One of nature’s most strange animals, flamingos have a habit of standing on one leg for hours on end, often sleeping in the same position. The flamingo’s strange stance has puzzled scientists for years.

Some theories have suggested that the birds stand on one leg to help reduce muscle fatigue and conserve body heat – which would be useful if they were in cold weather or water where heat loss is a problem. However, that theory is now contested by researchers.

Scientists have also argued that flamingos raise their legs to help dry the other foot, which can get very wet when they’re wading through water habitats. But this theory doesn’t explain why they do it or why they stand on one leg in the first place.

A new study suggests that flamingos actually stand on one leg for the opposite reason: to rest. Instead of using muscles to keep themselves upright, the birds use a mechanism called “stay apparatus.”

The stay mechanism is found in the knee and hip joints of flamingos and helps them stay balanced without any muscle activity. When the researchers tested this mechanism, they used a cadaver skeleton that had been put into the classic flamingo stance and then left there to see how well it remained stable.

They discovered that if a flamingo was in the stance and then leaned back, its center of pressure (CoP) moved significantly less. It was able to shift only about 3.2 millimeters. This was a tiny amount, but it’s a lot more than it would need to do if the bird were tucked up in a fetal position and asleep.

In the same way, when a flamingo was active and preening or jousting with its neighbors, it’s CoP made bigger adjustments. The scientists think the bird’s half-awake brain shuts off some of its neurons, allowing it to keep a steady, even stance on one leg while still keeping its body warm.

It might be this ability to maintain a steady stance on one leg that gives them the freedom to stand in the water for long periods of time without having to use any muscles, explains Rose. This could allow the flamingos to control their body temperature better and help them avoid hypothermia.

Another possible benefit of this stance is that it reduces strain on the heart. Because the heart doesn’t have to pump blood all the way down both legs, it can work more efficiently.

The flamingo’s ability to stand on one leg is probably an evolutionary benefit, too. Because it’s not likely that they’d be able to do this if they had only two legs, it could have helped the flamingos survive a longer period of time in the wild.

A flamingo’s legs are much shorter than their feet, so if they had only two legs, it would be very hard to balance on them for long periods of time. That could lead to muscle fatigue or injury, which isn’t good for a bird in the wild.