Subtitles section Play video Print subtitles We describe anyone with exceptional sight as eagle-eyed. But just how good is eagle vision? To put it to the test, Lloyd Buck and his Golden eagle Tilly are entering a remote part of Scotland. They're joined by Professor Graham Martin, an expert in avian vision. I'm intrigued to learn more about just how good her eye sight is. Ok. Well, I think we can set something up, sort of game of hide and seek, perhaps. Tilly must find Lloyd somewhere in this landscape. Her cage has been covered so she can't cheat. Lloyd has found a position 2.5 kilometers away on the other side of the Glen, and weather conditions are not ideal. Even with a powerful telephoto lens, it's hard to pick out Graham and Tilly. It's a long way. I cannot see you without a pair of binoculars and even with the binoculars, there's that much moisture in the air. So let's see what she does, now. This is the big test. Ok, then. Well, I'll release her now. Ok? Ok. Good luck. Come on, Tilly. Come on, Tills. She's off. She's looking very hard. I'm sure she's trying to find you. Tilly has never faced a challenge like this, but she appears to spot Lloyd almost immediately and makes her way to the other side of the Glen. Come on, Tilly. Come on. Interestingly, she takes an indirect route, riding a series of strong air currents to reach Lloyd more efficiently and more quickly. She's coming in. She's coming in fast. She's done it. Graham. Absolutely. Hammering across the valley. Oh, what a bird she is. You clever bird. What an eagle you are. Hey, hello. Graham, she's on my arm. That is absolutely incredible. I'm so pleased with that. I've never asked her to find me like that. That is actually very, very impressive because it took really very little time at all. Tilly spotted Lloyd in this vast landscape from 2.5 kilometers away. A feat so impressive, it seems almost superpowered. So how does she achieve this? Images are projected onto the retina at the back of the eagle's eye. This area is covered with light sensitive cells known as cones. The more cones, the sharper the eyesight. A human eye may have 200,000 cones per square millimeter, but eagles have over twice as many giving them the sharpest eyesight of any vertebrate animal. The eagles' supreme visual acuity gives them a significant advantage. It means they can quickly pick out prey in a vast landscape. But there's an unexpected downside to having such sharp vision. The problem is you don't want to get the sun in your eyes. It would destroy all the very high acuity it's got. So they have these big eyebrows. It's like wearing a baseball cap. That's all designed to keep the sun out of their eyes, so they don't actually ever image the sun. This brow ridge is what gives eagles their fearsome stare. But it has a serious drawback. Because if you've got to keep in the sun in your eyes, you can't actually see what's up there. What an eagle wants to do is patrol and look down at the big terrain below it and it's bending its head forward, it's tipping its head down to have a look. And that means that this blind area which is designed to keep the sun out of their eyes is stopping them actually looking where they're going. This blind spot isn't usually a problem. In their natural habitat, they soar high above the trees. But in a modern landscape, it can be a fatal flaw. Across the world, eagles are colliding with manmade structures. Wind turbines often built in wild landscapes can be a particular issue. So at this wind farm in Wyoming, they've placed observation towers around the site, and if an eagle is spotted, they switch the turbines off. But in bright light, eagles can be hard to spot. So now they're using artificial intelligence to improve the odds. This technology harnesses ten cameras to spot and track flying objects. They can work out if the object is an eagle in just one second and temporarily shut down any turbines in its path.