(dramatic music playing) NARRATOR: The peregrine falcon-- the world's fastest animal.
TOM FRENCH: Falcons in general have evolved to be fast and peregrine falcons have evolved to the extreme.
♪ ♪ NARRATOR: Living on the edge of what is physically possible, they seem to challenge the very forces of nature.
♪ ♪ They can reach speeds three times faster than a cheetah...
Withstand forces of gravity, twice that of fighter pilots... And will fearlessly attack prey double their size.
To understand their supernatural abilities, we're going to see the world through the eyes of this young peregrine.
He's going to be a little pocket rocket I think.
NARRATOR: And his unusual family.
Go, go, go, go!
Hey.
NARRATOR: We'll learn what it takes to become an elite high-speed hunter.
And by following a young family of peregrines in downtown Chicago... (squawks) Some of the world's leading scientists...
He's absolutely locked on.
The pupils wide open.
MAN: Woo-hoo!
NARRATOR: We'll reveal the secrets of the world's fastest animal.
Right now, on "NOVA."
♪ ♪ Major funding for "NOVA" is provided by the following: NARRATOR: At over 100 miles per hour, peregrines can launch a high-speed attack.
(squawks) They are one of the deadliest predators on the planet.
Like their cousins, the hawks and owls, they have sharp talons and keen eyesight.
But what makes them lethal is their ability to do something most other birds of prey cannot.
♪ ♪ They climb to great heights... and dive.
By folding their wings they can reach speeds around 200 miles per hour... to intercept and kill their fast-moving prey in mid-flight.
♪ ♪ It's a skill so remarkable it must be seen to be believed.
Their hunting prowess has made them one of the most widespread predators on Earth.
♪ ♪ They live on every continent, except Antarctica... ♪ ♪ from coastal cliffs... to arctic tundra.
Peregrine falcons are almost unique in being virtually world-wide.
The birds from the farthest north in the Arctic, migrate the farthest south, all the way down to South America.
Birds at our latitude in the central United States often don't migrate at all, they're sedentary.
But they're all recognizable as peregrine falcons.
NARRATOR: Peregrines have adapted to almost every habitat.
So what is the secret of their success?
To find out, we need to go back...
When all the potential of this high-speed flyer is held within one tiny egg.
♪ ♪ In the waiting room of a captive breeding facility, a rather unusual parent is patiently awaiting an arrival.
♪ ♪ It's captive breeding that's rescued peregrine falcons from the brink of extinction.
You're taking a long time, aren't you?
Are you going to come out and say hello?
♪ ♪ NARRATOR: Lloyd Buck grew up with a passion for birds.
(Rose whistles) Good boy, clever boy.
NARRATOR: Now, he and his wife Rose have a very special family of all types of birds-- including Arnie, Lily, and Moses, a four-year-old peregrine falcon.
Lloyd and Rose love and care for all of them.
ROSE: Good boys.
NARRATOR: With their feathered charges, like these two barn owl chicks, they educate children about the importance of protecting birds in the wild.
(Rose whooping) They also train them to star in films.
♪ ♪ But it's the peregrines that Lloyd most loves to train.
♪ ♪ As he puts his four-year-old peregrine Moses to the test-- he'll reveal what makes peregrines such effective, high-speed predators.
LLOYD: They're my ultimate bird, I've loved peregrines since I was a young boy.
As much as you fly them and as much as you get that bond with them there's always that little bit of wildness still there.
NARRATOR: And now, there will be a new addition to their family.
This egg is from a captive pair of peregrines.
The chick inside begins to cut a perfect line, using a tiny bump on its beak, known as an egg tooth.
(squeaking) Finally!
(chuckles) 60 hours of waiting.
No sleep and all of a sudden they've just gone crazy.
(chuckles) It's amazing to see.
Wow, look at that!
(chuckles) He's nearly out.
♪ ♪ And to think that this little chick, in about 45 days' time, will be fully grown and have everything it needs to be the fastest animal on the planet.
NARRATOR: Over the next few months, with Lloyd's expert guidance, the tiny chick will learn to master every skill needed to fly and hunt like a wild peregrine.
(seagulls squawking) In the wild, peregrine parents have just 12 weeks to teach their chicks everything they need to be a high speed predator.
In traditional coastal habitats peregrines raise their young on cliff ledges in nests called eyries.
(squawking) Here there is ample prey to feed the family, and room for juveniles to chase and learn to hunt.
But, these adaptable birds have recently moved into a whole new world... ours.
♪ ♪ One city provides a perfect window into their high-speed lives.
(siren blaring) (falcon squawking) Chicago, home to 2.7 million people... and more than 20 pairs of peregrine falcons.
(train clattering on tracks) This metropolis may not seem like a wildlife haven, but unlike many other animals, peregrines are thriving in cities.
FRENCH: Peregrine falcons only need two things to really prosper.
One is high spots to nest, and so ledges on skyscrapers and bridges provide ample nesting sites and flying birds as a food source.
And cities have a wealth of birds-- feral pigeons and starlings and house sparrows.
So cities are wonderful places for peregrines to be.
NARRATOR: And here in Chicago, as many as six nests can be found in one square mile of downtown real estate.
(falcon squawking) It's now early May.
In the window box of this 28th floor apartment, a female peregrine has three hungry mouths to feed.
(squawking) She makes a sharp call to encourage them to open their beaks wide.
(squawking) Her partner soon joins her on the balcony.
(squawking) This family is called the Perrys.
For the last three years, they've made their home on this balcony, watched by the man who lives here, Dacey Arashiba.
This rare situation provides an incredible opportunity to see what it takes for wild peregrines to grow up in a city.
At just a few days old, the chicks need regular brooding.
FRENCH: When the chicks first hatch, they're completely helpless, they can't even keep themselves warm.
So the female treats them as if they're still eggs.
She sits on them, broods them, she does that for the first two or three days.
NARRATOR: While the female tends the chicks, the male has his work cut out, hunting their next meal.
But city living has some surprising advantages.
As the sun beats down on Chicago's buildings, it generates rising thermals of hot air... ♪ ♪ Helping him to lift off and soar almost effortlessly.
♪ ♪ Chicago's waterfront location also attracts an abundance of migrating birds-- potential prey.
Peregrines normally hunt during the day, but street lighting means 24-hour hunting... ♪ ♪ Much needed help when feeding a growing family.
♪ ♪ (squawking) Now, at seven days old, the chicks have already fully opened their eyes.
(squawking) Peregrines rely on their vision to spot and track their prey at incredibly high speeds.
This sense is critical for their survival.
But just how good is peregrine eyesight?
♪ ♪ To find out, Lloyd's headed to the Lake District in northern England, with Moses-- a peregrine he's raised over the past four years.
He's wearing a falconry hood, to keep him calm.
♪ ♪ Lloyd's enlisted the help of avian sensory expert Graham Martin.
They will test how far Moses can see down the valley.
First, they fit him with a GPS telemetry device which tracks the exact distance he's flying.
Moses is trained to fly towards a bright yellow lure which Lloyd throws and catches.
For the first run Lloyd positions himself one kilometer, or .6 miles, away.
Okay, Graham, hood is off.
Hood is off.
NARRATOR: He throws the lure straight up in the air, trying to catch Moses' eye.
Gone, off, gone, gone, gone.
MARTIN (via walkie-talkie): 200 meters.
MARTIN: Very straight track to you, 400 meters.
NARRATOR: On the GPS, the straight track shows he's locked onto his target.
MARTIN (via walkie-talkie): 500 meters.
MARTIN: Crossing the stream now.
800 meters.
NARRATOR: Which is more than can be said for Lloyd.
Where is he?
MARTIN (via walkie-talkie): Just crossing over the river.
Ha, there he is, here he is!
Hey, hey hey hey.
Hey!
LLOYD (via walkie-talkie): I've got him, I've got him.
I had no idea where you were my boy till that last second.
NARRATOR: Spotting the lure at .6 miles seems easy enough for Moses.
But how will he fare when Lloyd doubles the distance?
Now.
Hood is off.
Hood is off.
NARRATOR: Even at 1.2 miles... Come on, Mo.
Come on.
NARRATOR: Moses heads straight for his target.
MARTIN (via walkie-talkie): 1.6 kilometers.
1.9 kilometers.
Oh, here he is, here he is.
MARTIN (via walkie-talkie): Two kilometers.
Good lad.
MARTIN (via walkie-talkie): Bird must be with you.
Brilliant.
(chuckling): Look at that, it's actually brilliant.
Well what do you think, I think we can just go for broke.
Do you want to try the three?
I think that would be a real push but we ought to try if he's so easily done 2K.
So yeah, let's try 3K.
LLOYD: Three kilometers, 1.8 miles.
So Graham's on that track in the very far distance.
It is amazing though, it's such a small thing really for him to see at that distance.
NARRATOR: Peregrine eyesight is twice as sharp as a hawk's.
But spotting a lure this far away is an incredible challenge-- no one is sure Moses can do it.
Hood's off, hood is off.
MARTIN (via walkie-talkie): Still looking down the valley, still looking for you.
Still looking... and he's off, he's off.
Keeping quite high.
Moving back towards us.
Coming right overhead now.
Just gone overhead.
NARRATOR: Moses appears to be struggling-- he circles to try and pick out the target.
MARTIN (via walkie-talkie): Moving towards you.
Come on my boy, come on.
Moving away from us now.
NARRATOR: And he locks on.
MARTIN: Definitely picked up a straight line now.
1.4... MARTIN (via walkie-talkie): 1.8.
Come on!
Just going directly away from us.
MARTIN (via walkie-talkie): 2.8 kilometers, must be very close to you now.
Come on.
MARTIN (via walkie-talkie): 2.9 kilometers.
What a boy!
You top man!
He's on the lure, he's on the lure, so he's done it.
(laughs) You are a mean machine!
Come on.
LLOYD (via walkie-talkie): Amazing, Graham.
I'm quite impressed with him to be honest.
Brilliant.
Well done.
Excellent.
Whoo!
NARRATOR: Incredibly, the GPS telemetry device shows Moses spotted the lure from almost two miles away.
Good boy.
Well done, young man.
NARRATOR: So exactly how is he able to do it?
Peregrines have large eyes taking up at least 50% of their skull.
For us, it's only 5%.
♪ ♪ The optics of the eye project an image of the world onto the retina-- shown here in red.
The most important part of the retina is called the fovea.
It's responsible for seeing objects in fine detail.
It's where light-sensitive cells called cones are most concentrated.
But the peregrine has two foveas on the retina of each eye allowing it to see more of the world in detail.
The first is for spotting close objects.
Here, the peregrine looks through both eyes, using binocular vision.
The second is for spotting things far away.
Now, the peregrine looks sideways, through one eye at a time.
♪ ♪ So to spot a target almost two miles away... Moses turns his head as if staring through a telescope.
♪ ♪ As he closes in, he switches to binocular vision which gives very accurate information on the location of his fast-moving target.
This superior eyesight gives peregrines a big hunting advantage.
Any of the species that you care to think of that he preys upon, his vision is so much better.
For something like a pigeon, he's four times better in his acuity.
NARRATOR: This means a peregrine can spot its prey, and gather speed for an attack, long before its prey knows it's coming.
So at three kilometers, say, he can see the prey, but the pigeon wouldn't see him until he was only three quarters of a kilometer away.
The vision difference translates into a really important time difference when you're actually hunting prey.
NARRATOR: This is a crucial advantage, especially when it comes to feeding a growing family.
The Perry family certainly is growing-- and fast.
♪ ♪ (squawking) ♪ ♪ The Chicago chicks are now five weeks old and about 30 times heavier than when they hatched.
They've been ringed, sexed, and named by The Chicago Peregrine Program.
This is Tyler, his sister, Commodore, and brother, Fred.
(squawking) Each will be monitored as part of North America's population of peregrines, which was nearly wiped out in the 20th century due to the insecticide DDT.
FRENCH: We didn't realize at the time that it accumulated through the food chain.
And for peregrine falcons, the primary effect it had, was to cause the female to lay thin-shelled eggs.
So they'd break.
It didn't take very long before populations of the most affected birds began to crash.
NARRATOR: In 1972, DDT was banned, and soon after captive peregrines were bred and released into the wild.
FRENCH: Peregrine falcons have responded dramatically to conservation efforts.
Their numbers have rebounded completely.
NARRATOR: So much so that peregrines are now thriving in diverse environments, even in our homes.
(engine running, stops) Today the newest member of Lloyd's family has come home.
It's been 12 weeks since Lloyd watched him hatch.
Good boy.
NARRATOR: He's now fully grown.
Hello.
Hello.
You all right?
Oh, he's lovely.
He is, isn't he?
He is, he's a real sweetie.
Yeah.
NARRATOR: Lloyd's called him Rudi.
There he is, little Rudi.
ROSE: I don't think we've ever had a falcon so calm so quickly.
♪ ♪ NARRATOR: Over the next few months, Lloyd will teach him the skills a young peregrine needs.
But first, it's critical that Lloyd earns his trust.
He must sit quietly and avoid eye contact.
This helps Rudi relax and he tucks in to his first meal.
It's an important step, as now, training can begin.
Using the traditional art of falconry, Lloyd will teach Rudi to hunt a yellow lure.
♪ ♪ He starts with a line attached to Rudi's foot for safety.
First, a small hop.
That was brilliant, he's a good boy.
So he's just building that bond, and now I've got this lure, and it's a good game.
NARRATOR: Then a little further... Rudi!
Rudi!
♪ ♪ You didn't brake Rudi, that's what your tail's for.
Rudi!
Hey!
NARRATOR: And with no string attached.
(chuckling): Good boy.
So that's his first free flight today.
He's shortcut the whole process by about four days, because he's progressed at his own speed, which is what you want.
Rudi!
NARRATOR: Finally, he needs to catch it in the air.
Hey-ah!
Good lad, here.
Here.
♪ ♪ Ooh, nearly.
♪ ♪ Ooh, good boy.
Good lad!
NARRATOR: In less than a week, Rudi has learned the goal of the game.
He responds to the lure as if it is prey and understands he needs to catch it in the air.
Luckily, juvenile peregrines have a secret to help them hone their hunting skills.
Of course this year he's in his juvenile plumage year.
So his tail's a bit longer, his primaries are little, and they're slightly softer feathered in their juvenile year, to allow them room for error it's thought, so they can hone and learn their hunting skills.
Next year, that tail will get a little bit shorter and the feathers will come stiffer and harder.
This sleeker plumage is thought to help adult peregrines to fly faster.
But fewer than half of peregrines make it to adulthood.
Learning to catch food at high speeds isn't easy.
You couldn't get a better example, really, of survival of the fittest than with these guys.
They've got to be at the top of their game all the time.
Once their parents stop feeding them and they're fledged, they're on their own, literally.
NARRATOR: Back in Chicago, it's just seven weeks until the chicks go it alone.
And they need up to 11 meals a day to sate growing appetites.
Luckily, their parents are expert hunters... And the city provides abundant prey.
♪ ♪ A city diet can consist of over a hundred different species, many not even found in less developed environments.
♪ ♪ And their favorite?
(wings flapping) Pigeons.
But they can be a challenge to catch.
♪ ♪ In a straight chase, a pigeon can reach 50 miles per hour and weave and dive among city buildings for cover.
♪ ♪ But even between the buildings, peregrines can execute a perfect strike at lightning speeds.
Just like this.
So how do peregrines catch their prey?
Lloyd and avian expert Graham want to find out more.
But first they need to simulate a hunt.
♪ ♪ Meet the prey drone, designed by gadget guru Chris Watts.
(drone buzzing) It's capable of performing aerial maneuvers that mimic bird flight.
♪ ♪ And with safety guards and an onboard camera, it's the perfect device to film a peregrine in hot pursuit.
♪ ♪ For the battle arena, a secluded valley in the U.K.'s Lake District.
So are you set?
I'm all set, yeah.
Okay.
Okay, going up now?
Yeah, yeah.
You happy?
Yeah.
NARRATOR: It's the prey drone.
MARTIN: Get your position.
NARRATOR: Against Moses, Lloyd's four-year-old peregrine.
Let's go.
LLOYD: Go, go, go, go!
Go, my boy.
MARTIN (on radio): Bird's gone, bird's gone.
WATTS: Wow, look at that, straight after it.
Not yet, stay as you are, stay are you are, stay as you are.
Climb, climb, climb, climb, climb, climb!
♪ ♪ WATTS: Okay.
Shall I come back down?
LLOYD: No, no, hold your height, hold your height.
Hold it there, hold it there.
Dive, dive, dive, dive, dive!
♪ ♪ NARRATOR: No matter what the prey drone tries, the result is the same.
LLOYD: Got it!
WATT: Oh, yeah, I felt that.
NARRATOR: Every time.
LLOYD: That's it, I think he got it then.
Just like that.
See that?
NARRATOR: So how does Moses pull off a perfect strike?
His long, pointed wings offer little drag, allowing him to fly faster, helping him to close in.
But he rarely chases directly after the drone.
Instead he aims his attack ahead of the drone's current position.
♪ ♪ Recent research suggests that in order to intercept his target, as Moses approaches the drone, he reacts to its movements to keep it in his line of sight.
He can then close in to intercept the flight path of his quarry.
But what about the strike?
The drone camera provides a rare and unique view of this moment.
Right, Let's have a look.
Here we go.
Just so you know, this is, this is real time, this is how quickly it actually happens.
LLOYD: Wow.
Whoa!
That's so fast.
Wow, real time is very fast.
We'll need to see that much, much slower to understand what's going on.
We should be able to just go through frame by frame and... LLOYD: There he is, there he is.
MARTIN: Look at that, he's still absolutely stable.
The pupils wide open, absolutely he's absolutely locked on, feet well spread, talons spread.
LLOYD: There then, look.
NARRATOR: The strike took just one fifth of a second.
But the final component of a perfect catch is a set of deadly tools.
Their feet have callous-like pads for extra grip and talons to lock onto their prey.
Like other raptors, their long toes work as a ratchet mechanism.
Once their feet grip their prey, they don't need to clench their muscles to hang on.
But it's the powerful beak that makes the kill.
A horn-like bump called a tomial tooth is used to dislocate the prey's neck.
♪ ♪ These deadly tools and an elite targeting system combine above the Chicago skyline... to produce a perfectly timed strike.
This is an essential skill for all young peregrines to master.
But first, they need to learn to fly.
And in a city, this can be treacherous.
♪ ♪ FRENCH: That very first year after leaving the nest is the most dangerous year for them.
And the greatest cause is hitting stationary objects.
(horn honking) As young birds, they know how to pour on the steam, but they often don't know how to stop or maneuver, and they hit things.
NARRATOR: The nest is down to two.
♪ ♪ Tyler has made his way onto the ledge above.
(squawking) His siblings seem more cautious.
But their parents are trying to entice them away from the nest by carrying their next meal out of their reach.
If the chicks want food, they'll need to take a leap of faith.
♪ ♪ Tyler tries for the roof of an adjacent building, but landing is tricky.
Luckily, a balcony saves the day.
And soon, his courage is rewarded with a meal from his parent.
♪ ♪ A few days later, Tyler greets his sister Commodore.
Finally, Fred joins his siblings.
♪ ♪ The trio are unlikely to return to their birthplace on the balcony again.
Now that they are fully grown, the typical size difference between genders is clear.
Like all female peregrines, Commodore is roughly a third bigger than her brothers.
This difference in size is thought to allow a peregrine pair more variety in the prey that they are able to hunt.
For the fledglings, the first few days are full of challenges.
They have difficulty adapting to Chicago's famous wind... ♪ ♪ Navigating obstacles.... ♪ ♪ And they simply don't know which areas to avoid altogether.
♪ ♪ Thankfully, their parents are still providing food, although not for long.
♪ ♪ Time for a more advanced lesson-- the food pass.
Adults share kills this way.
♪ ♪ No luck this time.
♪ ♪ So the mother arrives to show how it's done.
In the wild, the food pass is instinctual, but they practice it with their parents' encouragement.
(squawking) Lloyd and Rose take the place of parents to train five-month old Rudi how to do it.
Since Lloyd can't fly, he's using a car.
LLOYD (on radio): Rose, there's a bit of rain coming in soon, so let's head back to base.
NARRATOR: It can cruise along at 25 miles an hour, slow enough as to not tire out young Rudi.
And its open top allows Lloyd to safely pass Rudi the lure.
Slower, slower, hold it there, hold it there.
Quicker, quicker, quicker.
(gear grinding) ROSE: Oh, come on.
There he is, here he is.
Ooh.
Woo-hoo!
Hey!
LLOYD: Incoming.
We're nearly at the end.
Yeah.
Ooh.
Have to stop.
Yeah, stop.
Rudi, hey!
NARRATOR: Even after several tries, Rudi doesn't manage to catch the lure.
...stop, Rudi.
He's going down.
Yeah.
Yeah, he's down.
Good lad.
On there.
Rudi.
There's a good boy.
NARRATOR: Time for round two.
Okay, go.
Here he goes.
Go, go, go, go, go, go.
Quicker, quicker, quicker, quicker.
Quicker, quicker.
Faster, faster.
Hey, hey!
Incoming, slower.
Slower.
Now speed up Rose, yeah, go for it, go for it, go for it!
Faster, faster, faster, flat out, flat out, flat out, flat out, hey.
Slower.
Incoming.
Hey, hey, incoming.
And slower, not yet, okay.
That's it, yeah quicker, quicker, quicker, go, go, go, go, go, go!
Go, go, go, go!
Hey, hey, hey, slower, slower.
Ready, ready, ready, he's yours.
Whoo!
(chuckling): Good lad.
NARRATOR: Finally, a perfect strike.
Good boy.
Ah, that was brilliant.
There he goes.
NARRATOR: Rudi has learned to chase down and catch a target-- in a simulated food pass.
In Chicago, the eight-week-old fledglings have become proficient flyers.
They spend hours chasing each other.
What looks like play is also essential to hone their hunting skills.
♪ ♪ But a poorly timed practice can turn perilous in an instant.
When a fledgling tries to grab live prey... it fails and pulls out, leaving its diligent parent to pick up the dropped food.
This is unusual behavior for an urban peregrine.
They rarely venture close to the ground, as the city streets are too dangerous.
(cars honking) The peregrine parent manages to fly away unscathed.
(squawking) But there is still one final skill for the fledglings to master before they reach independence-- perhaps the hardest and most perilous of them of all.
It is the peregrine's greatest hunting strategy and the key to being the fastest animal in the world.
♪ ♪ FRENCH: In flat flight, a feral pigeon is an even match for a peregrine falcon, and it can often get away.
So a peregrine has to have another strategy.
It builds altitude, gets the thermals to help it get up into the air.
♪ ♪ And then when it sees a prey item flying by, it folds its wings, and it starts to plummet.
It is evolved to be the fastest animal on the planet when it is in a steep dive or a stoop.
♪ ♪ NARRATOR: In the stoop, peregrines reach speeds of around 200 miles an hour, to catch even the fastest birds.
The stoop is their most iconic aerial maneuver.
But how do they dive so fast?
♪ ♪ To find out, Lloyd's brought his four-year-old peregrine, Moses, to one of the highest cliffs in Britain.
♪ ♪ Fleetwith Pike stands a staggering 2,126 feet above the valley floor.
♪ ♪ And to entice Moses down?
The drone is back.
At the bottom is aerodynamic scientist Christoph Bruecker, recording Moses' speed using GPS telemetry.
LLOYD: Come on, Mo.
This is it, my boy.
(drone humming) He's looking.
(on radio): He's looking.
Keep moving it around, Chris.
He like... he's gone, he's gone, he's gone, full stoop, full stoop.
(exclaims) LLOYD (on radio): There he goes.
Holy smoly.
No, it's already at 150 kilometers per hour.
(chuckling happily) ♪ ♪ BRUECKER: Wow!
Wow, great.
(exclaiming) LLOYD (on radio): Hi, Christoph.
He looked pretty good from up here, he went off like a little rocket.
What, what kind of speed did we get?
So the maximum speed what we get (on radio): was 170 kilometers per hour.
LLOYD (chuckling on radio): Well done, superb.
♪ ♪ NARRATOR: Moses reached over a hundred miles an hour in just two seconds.
Although this is a relatively leisurely pace for a peregrine.
They will only go as fast as they need to.
But watching peregrines stoop like this has helped Christoph to understand how peregrines reach top speeds.
(lights clicking on) In the laboratory, he and his team have created exact replicas of peregrines and placed them in wind tunnels.
These experiments are revealing how a specific body position, called the cupped wing, might help peregrines reach high speeds.
♪ ♪ In this streamlined shape, drag is reduced and air is directed under the wings through a narrow channel.
When air is squeezed into a gap, it flows faster, helping to increase the peregrine's speed.
This is the Venturi effect.
Formula 1 cars use the same principle to increase grip and go faster.
Research suggests that by using the Venturi effect, the peregrine can reach speeds up to 150 miles an hour.
To increase its speed further, it's thought the bird wraps its wings around its body and effectively goes into free fall-- a rare, high-risk maneuver, as no wings means no control.
Any error could result in a fatal crash.
♪ ♪ Maneuvering at such high speeds exerts huge pressures on the body.
So what protects the bird?
A membrane covers their eyes during the stoop, just like a pair of built-in goggles.
Nasal cones are thought to slow airflow, helping the peregrine to breathe.
And with strong bones and a stiff tail, they can withstand forces up to 18G in a high-speed turn-- twice that of fighter pilots.
This means a stooping peregrine can pull out of a dive and still maintain high speeds.
This is key to catching their prey.
Flying at the very limits of their ability requires extraordinary control, skill, and experience, and it's a lot to learn for any young bird.
Lloyd has brought six-month-old Rudi to a hilltop in Somerset to teach him this final lesson.
Hey.
Hey-ya.
NARRATOR: Strong winds generate updrafts, which should encourage him to gain height and speed.
Will Rudi master the stoop?
Hey, hey.
NARRATOR: He makes a few false starts... but instinct kicks in.
Hey.
NARRATOR: Rudi performs his first-ever stoop.
♪ ♪ For all peregrines, wild or human-raised, the formula for high-speed diving is written in their genes.
♪ ♪ LLOYD: It's perfect conditions today.
Really good updraft up through this gully here behind us and up onto the hill.
He's absolutely, really loving it.
♪ ♪ And he's fit and strong now, he's looking nice and strong and fit on the wing, he can sustain that speed, he can tolerate all that pressure on his muscles and just keep it going.
NARRATOR: Rudi has mastered the major skills a peregrine needs to be a high-speed hunter.
In Chicago, the fledglings have also now learned everything needed for an independent life.
And city living will give them the best chance possible since urban peregrines have a higher chance of making it through their first year than their country cousins.
But it's now up to them to go it alone when the time comes.
And when they do, they'll rely on those special skills that set peregrines apart.
♪ ♪ Oh, come on, come on.
NARRATOR: Peregrines are able to spot distant prey.
MARTIN: Any of the species that he preys upon, his vision is so much better.
NARRATOR: They can calculate and time a perfect catch.
MARTIN: Literally in no time at all those talons suddenly going bang!
♪ ♪ NARRATOR: And drop out of the sky to reach world-record speeds.
FRENCH: Peregrine falcons may be one of the most specialized bird of prey, 'cause they're the fastest of all of them.
They are absolutely spectacular.
NARRATOR: The peregrine falcon is one of the most successful predators and, without a doubt, the world's fastest animal.
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♪ ♪