The Bat Signal How do Bats Drink Without Falling In

My favorite science story this week is about bats. The big question is, how do bats drink water? In sense, we already know because they just go down to the water and stick their face in it and drink and then fly away. But in another sense, we don't know because when bat flies, it stays in the air by flapping its wings. And when it flaps its wings, the wing tips come down so low that bat won't be able to drink. So, what do they do when they get close to the water when they're drinking? Until now, nobody's known. But thankfully somebody at Cornell did study. This study was done in China with two different species of bats. small one about the size of chickity, maybe little bit smaller than that called rhinolofus ferumacinum. And then the other species was bigger one that's almost as big as robin but not quite. And that one is called hippocerus pratty. Anyway, they took these bats, they didn't give them water for little while, and then they put them in room with water or they brought water into the room. I'm not sure which. In any case, the bats drank. And as they drank, the researchers made high-speed videos of them. And here's what they found. Bats that are drinking change their wing motions in two very important ways. The first one is that they flap their wings with smaller amplitude. In other words, the up and down motion of the wings is decreased by about 50%. And that is pretty obvious what the function of that is. It just prevents those wing tips from getting too low, so they stay out of the water. That's cool. but it decreases the amount of lift that bat can get from its wings. So they do that second change and the second change is increase the wingbeat frequency. So when you look at how fast they're flapping their wings close to the water, it's about 50% higher than the normal flapping frequency for those species when they're in the air away from the water. So that's great. You get quick answer as to how bats are able to take drink of water. But there's one more piece of the puzzle which is really interesting, which is that as bats get close to the water, they get an extra little bit of lift from something called ground effect. Ground effect is this aerodynamic phenomenon that gives extra lift if you're flying close to the ground or close to the water. Any solid surface that's going to prevent the air from moving down any further is going to give you an extra aerodynamic boost. And you can kind of think of it as, you know, if you're flying way up high in the sky and you push the air down, it just keeps going down. But if you're really close to the water and you push down on the air, it's going to hit something and that's going to create resistance and it's going to eventually push back on your wing and lift you up little bit better. So the bats that are taking drink seem to get an extra boost from ground effect. And that's part of the story as well. It's nice little story and it's bats drinking water. And honestly, bats drinking water is one of my favorite things about them because the photos that you get are just so unbelievable. Especially this one taken by Brock and Cherry Fenton, which use as the banner for the bat signal, which is my weekly email about science stories. If you're not getting this banner in your inbox every Tuesday, you should sign up. Just go to followthebats signal.com.