How peregrine falcons survive a 200-mph dive

HostMost of us feel the wind pushing hard against us if we just run down a hill. If you stick your hand out of a car window on the highway, you can feel that heavy shove of the air trying to knock your arm back.

HostBut then there's the peregrine falcon. It can drop out of the sky at over two hundred miles an hour, which is faster than a race car. How does a living thing made of flesh and feathers not just fall apart at those speeds?

GuestIt's a massive challenge for any living body. When you move that fast, the air stops feeling like thin gas and starts feeling more like a thick liquid. It wants to crush you and pull you apart at the same time. The first thing a falcon has to deal with is just being able to breathe. If you or I tried to open our mouths at two hundred miles an hour, the force of the air would be so strong it would basically blow our lungs up like a balloon until they popped. The air would be moving too fast for us to actually pull any of it in.

HostSo does the bird just hold its breath the whole way down?

GuestNo, they actually need that oxygen to keep their muscles working during the dive. They have a very clever trick in their nose. If you look closely at a falcon's nostril, there's a tiny little bone in the middle shaped like a cone. We call it a tubercle. It acts like a speed bump for the wind. When the air hits that little cone, it breaks up the flow and makes it swirl around. This slows the air down just enough so it can enter the lungs at a safe speed. It's a piece of natural engineering that's so good that jet engine designers actually looked at it when they were trying to figure out how to keep air flowing into engines at high speeds.

HostThat sounds like a lot of extra gear to carry around. I would think having little cones in your nose and heavy-duty lungs would make the bird too bulky to fly well the rest of the time.

GuestWell, everything about them is a trade-off. Their bones are hollow to keep them light, but they're reinforced with internal struts like a bridge. And their feathers are different too. If you touch a regular backyard bird, the feathers are soft. A falcon's feathers are stiff and oily. They tuck them in so tight that their body becomes a hard, smooth teardrop shape. This keeps the wind from getting under a single feather and ripping it off. But the real danger is actually the eyes.

HostI was going to ask about that. If a tiny bug hits your eye when you're riding a bike, it hurts. At two hundred miles an hour, a grain of sand would be like a bullet.

GuestExactly. To solve that, they have a third eyelid that's completely clear. They can slide it across like a pair of goggles. It protects the eye from dust and the drying wind, but they can still see through it perfectly. And they have to see because they're steering. Their eyes are actually locked into their skull much tighter than ours. They have these two different focus points in each eye. One lets them look straight ahead like a telescope, and the other lets them look out to the side. They can track a target from a mile away while they're screaming toward the ground.

HostWait, if they're that stiff and moving that fast, how do they steer? If I try to turn a car even a little bit at high speed, I might spin out or flip over. It seems like the bird would just tumble.

GuestThey're making tiny moves the whole time. If they want to turn, they just barely stick out one wing tip or shift their tail an inch. At that speed, even a tiny change creates a huge amount of force. They have these special feathers on their back that pop up if the air starts to flow the wrong way. It's like the flaps on the wing of a plane. They feel the air starting to get messy, and those feathers pop up to smooth it back out. It keeps them from spinning out of control.

HostBut eventually they have to hit something. They're hunting, right? Slamming into another bird at two hundred miles an hour sounds like a good way to break every bone in your own body.

GuestIt's a huge impact. They don't usually grab the other bird with their claws right away. Instead, they ball up their feet into a fist and punch the prey. The force of that punch is usually enough to end the hunt instantly. To survive that shock, the falcon has a very thick chest bone and a very strong neck. They also have to time it perfectly. Just before they hit, they spread their wings to act like a giant brake. They go from two hundred miles an hour to almost nothing in a split second.

HostIt seems like a huge risk to take just for a meal. One wrong move or a sudden gust of wind and the bird hits the ground instead of the prey. Why did they end up with such a dangerous way of life?

GuestIt's all about the competition. They hunt other birds that are also very fast and very smart. If the falcon was just a little bit faster than a pigeon, the pigeon might see it coming and duck away. By going this fast, the falcon becomes a ghost. The prey never even knows it's there until the hit happens. It's the ultimate high-speed game.

HostThe real mystery is how their brain can even think fast enough to make those choices, because at those speeds, the ground is coming up much faster than any animal should be able to handle.

GuestThat little bird sitting on the edge of a skyscraper suddenly looks less like a city neighbor and more like a fighter jet waiting for a green light.