Flamingos are one of the most enthralling and surprising animals found in nature. We know why they have pink feathers (because of their food), but there are still a good number of competing theories about another of their most distinctive characteristics – including why they mostly stand on just one leg. Let’s check them out.

With their plumage and long legs and necks, flamingos (Phoenicopterus) can’t be mistaken for any other bird. They’ve long fascinated people. A cave painting of a flamingo was even found in Spain, dating back to 5,000 B.C, and images of flamingos can be found today all over, from plastic lawn ornaments to literature, such as in the case of Lewis Carroll, the author of Alice in Wonderland. 

Understanding flamingos

Flamingos are social birds. They live in groups of different sizes, from just a few pairs to thousands — or even tens of thousands. Such big numbers make the world-famous flamingo displays even more impressive.

The purpose of these large gatherings is to stimulate hormone production and ensure that as many birds as possible will breed. They seem to be doing a good job so far as no flamingo species is currently considered endangered. Still, with many wild species, the threat of habitat loss due to road construction and housing development is causing some populations to be threatened. In 1989, 100 flamingos died in Mexico from lead poisoning after eating lead shot. 

Flamingos live in lagoons or shallow lakes, which frequently are too salty or caustic for other animals. That’s why sometimes their only neighbors are algae, diatoms and small crustaceans — which often end up being their dinner. In-flight, flamingos are quite distinctive, with their long necks stretched out in front and their equally long legs trailing behind.

The Andean flamingo (Phoenicoparrus andinus) is considered the rarest of the flamingo species. It lives high in the mountains of Chile, Peru, Bolivia, and Argentina. Expansion into their habitat with farms, roads, and urban development, has put them under higher pressure. Chile has established a flamingo reserve around the lakes they use for breeding colonies.

Many of the features inherent to the flamingo can be explained by some relatively simple science. They have long legs and necks to help them get food — evolution favored individuals that can feed in both shallow and deep water without getting wet. If food in shallows gets scarce, flamingos can feed by muddying the water and digging with their beaks.

The flamingo’s pink or reddish color comes from the rich sources of carotenoid pigments in the algae and small crustaceans the birds eat. We eat carotenoids too, like those in carrots and beets, but not enough to turn us orange. American flamingos, a subspecies of greater flamingo, are the brightest, with red, pink, or orange on their legs and faces.

They engage in collective displays, where hundreds or even thousands of flamingos can coordinate head-flag, wing-salute, twist-preen, and marching movements. Flamingos also spend a lot of time grooming, where they distribute oil secreted from the base of their tail to their feathers. This helps waterproof the bird’s body. 

Why flamingos stand on one leg

If you see a flamingo anywhere in the world, it’s likely standing on one leg, with the other one tucked tight against is feathered body. Why does it do that?

This is a surprisingly difficult question to answer, with expert zoologists offering several theories over the last few decades. 

A study of flamingo cadavers from 2017 found that they can passively support their body weight on one leg without any muscle activity, but they cannot maintain balance holding a two-legged pose. The researchers also found that live flamingos in a zoo sway less when they stand on one leg. It’s unclear how they might do this, though.

Like all birds, flamingos are warm-blooded, with resting body temperatures hotter than the surrounding environment, even under relatively extreme conditions. They run a bit hotter than the average human (37°C) at 41ºC, so they lose heat faster than humans when standing on land exposed to the outside air. 

But what happens if a flamingo stands in the water on two legs the same way they do on land? In this case, they can lose much more body heat — so if a flamingo learns to stand on one leg instead of two when it’s in the water, it can conserve its body heat much more effectively.

A 2009 study has generally been accepted by biologists and zookeepers, suggesting that flamingos pull one leg up close to their body to conserve heat that might otherwise be lost while standing in cold water. Indeed, body temperature seems to be the main driver (or one of the main drivers) that make flamingoes stand on one leg.

A flamingo with two legs in the water loses between 140-170% more body heat than a flamingo on one leg, studies have shown. This means that flamingos that learn how to stand on one leg can spend more time in the water doing the things they like, such as feeding with crustaceans, grooming, and scouting the waters. 

That’s why a flamingo that stands on one leg probably has more chances for evolutionary success and even survival than one that stands on two legs. As far as scientists can tell, there’s no gene for standing on one leg; rather, it’s a behavior that gets passed down from a mother flamingo to her offspring as she raises them.

Other possible theories

Still, not everyone is convinced, and some researchers have suggested other theories. Standing on one leg might reduce muscle fatigue for flamingos, or enable them to move more quickly if they suddenly have to escape a predator. The researchers argued that this is likely due to the posture engaging a central point of force, which allows for less muscle activity.

“It’s an energy-saving activity, basically,” Paul Rose, zoologist at the University of Exeter, told BBC.  “Believe it or not, flamingos are more stable for long periods of time on one leg than they are on two. This is because the ligaments and tendons in their legs can be locked in position – and that reduces any muscular effort to stay in one place.

Another theory also suggests that flamingos, like whales and dolphins, are essentially able to turn off half their brains when they sleep. Standing on one leg is a natural reflex that helps them maintain their balance and keeps them from falling over. But ornithologists admit that no theory so far has been confirmed with certainty.

Flamingos aren’t the only animals to engage in this behavior. Ducks, geese, and swans also use similar locking mechanisms in their legs to stay perfectly balanced. “So many birds stand on one leg. It just so happens that because flamingos have such long legs, we see it more,” said Rose. We can even see this behavior in humans at some extent, resting more weight on one leg than the other if they are in a queue.

While it seems difficult to decide on a single theory on what they stand on one leg, one thing is certain. Flamingos are amazing animals and we have to keep learning about them.