Thanks to Brilliant for supporting this episode of SciShow.

Go to Brilliant.org/SciShow to learn how you can take your STEM skills to the next level! [♪ INTRO]. If you’re a fan of lawn ornaments, maybe you just live in the state of Florida, you might have a plastic flamingo or two.

If you do, there’s a pretty good chance that it’s pink, it’s a little bit tacky, and, of course, it’s standing on one leg. And I’m not saying this as an insult: real flamingos are also pink, a little tacky in an “evolutionarily oopsie” sort of way, and often they are found standing on one leg. And I’m not here to criticize them.

If you asked me to stand on one leg all day long every day, like, my days would need to be shorter. So, what is it that makes flamingos different? Why are they the one-legged champions of nature?

For a long time, people kind of just assumed that flamingos did this to conserve heat. In fact, that’s what we thought when we did our first episode on why flamingos stand on one leg. Which we are now taking down off the internet.

It makes sense to think this; cats do something similar, informally called “loafing,” when they tuck their limbs in to make themselves look like a loaf of bread. And they might do this because it stops them from losing heat in their extremities. But that explanation... it did not make sense to bird researchers.

See, some birds have a network of closely-packed blood vessels in their legs that are really good at recapturing and conserving body heat. So they already conserve heat naturally without having to resort to behaviors like loafing. But here’s the really weird bit: like your plastic lawn ornament, a flamingo doesn’t actually have to be alive to successfully maintain a one-legged standing position.

That somewhat horrible truth is the result of one very weird experiment. Researchers were compelled to ask this macabre question because they knew that flamingos will often sleep while standing on one leg. Which would be exceedingly difficult if it wasn’t something that came really, really easily to them.

I mean, like, have you even ever tried to prop up your own head while sleeping on an airplane? Like, you can’t even do that without...gah. But as it turns out, flamingos don’t have to invest that much muscle power to stay upright.

Scientists confirmed this by taking dead flamingos and propping them back up on one leg. Which makes you wonder what they say when people ask them what they do for a living at a party. If this sounds weird, though, it actually is probably a little bit more kind to use a cadaver than it would be to wrangle a live bird like this.

They discovered that a fresh, floppy flamingo corpse was quite stable on one leg, despite, you know, being dead. The most stable position was with the foot directly beneath the bird at the precise angle that triggers the joint lock that stops the bird from toppling over while sleeping. Basically, it’s a system that’s based on gravity.

The flamingo’s center of mass is in just the right place, in front of its knee, and the knee itself can only move in a limited way. So when the foot is placed at just the right angle, the flamingo’s weight is all that’s needed to lock the joints in its leg, thus making it possible for even a dead flamingo to stand on one leg with minimal assistance. And, when propped up on two legs, the cadavers weren’t stable at all, so that was a nice little bow to wrap on their very weird study.

They did also test their theory on live flamingos, by the way, but more gently. They had their living subjects stand on force plates, devices that measure the forces generated by movement, and then waited for them to fall asleep. The force plate data told the researchers what was happening in the flamingo’s foot when its body was in motion, during both active and quiet moments.

The live flamingos were extremely stable on one leg, with the flamingo's center of gravity held just-so over its leg, kind of like an upside down pendulum. So what’s up with this? Well, the one legged posture saves energy, and is just easier for the birds.

In short, flamingos, whether alive, dead, or plastic, are perfectly adapted to standing on one leg, and that’s just fine by them. You thought this episode was going to be about biology, when it’s mostly about the physics of flamingo joints! But worry not!

If your physics skills could use some help, there is Brilliant. Like their course “Physics of the Everyday,” though whether or not flamingos are everyday depends a bit on where you live. They’ve got 60-plus interactive courses on math, basic science, and computer science too, so you can cover as many of those gaps as you want.

If you’re interested, you can check out Brilliant.org/scishow for a chance to get 20% off an annual Premium subscription. And thank you for your support. [♪ OUTRO].