Masters of the Sky Life in the Air

The sky is one of the most challenging places to live.

But all across the world, extraordinary animals do

something we can only dream of...

..take to the air.

Some spend their whole lives up here.

Others only visit for a moment.

We'll discover how many incredible animals thrive in the sky...

..and what clever tricks they use to get airborne.

With the help of some specially trained animals,

the latest technology and special effects techniques,

we'll reveal brand-new discoveries

that explain how animals take to the skies.

This is Life In The Air.

It's one thing to take to the air

and let gravity do the rest...

..but to stay airborne,

to master true flight,

you need to push the laws of physics right to the very edge...

..using power, speed,

agility, endurance

and acceleration.

These are the masters of the sky.

Meet the whooper swan,

one of the largest and heaviest of all flying creatures.

Every year, families fly enormous distances,

migrating between vital feeding and breeding areas.

But weighing a whopping 14 kilos,

how are swans able to fly at all...

..let alone so far?

To push the limits of what's possible in the air

they need strength - and lots of it - every day.

To fuel their huge bodies, swans need to eat

over a kilogram of vegetation a day.

They're constantly in search of enough food to survive.

And that means flying.

But when you're this size, just taking off

is nearly impossible and requires some very clever techniques.

So, how does he do it?

To get airborne, he's going to need raw power...

..and apply it in a very precise way.

First, he must break free of the water,

but it clings to his body, holding him back.

His huge webbed feet need to drive him upwards and forwards.

Now his gigantic metre-long wings can move freely.

They push air down and back, delivering yet more power

to accelerate him further.

Wings and feet work together to give him the speed he needs to take off.

Once at this speed,

the air is moving fast enough over his wings to create a huge

upward force called lift.

This fights the downward pull of gravity.

So how is lift created?

The special shape of his wing, known as an aerofoil,

causes air to flow differently above and below his wing,

and this affects its pressure.

With low pressure above and high pressure below,

the wing is pushed upwards.

The faster the swan goes, the more air flows over the wing,

and that creates more lift.

He needs to reach 21 kilometres an hour,

the critical speed where lift cancels out gravity altogether.

Then it's undercarriage up, and we have takeoff.

For such a huge bird to take to the sky,

everything must come together in one explosive moment

that lasts just a few seconds.

Once he's really flying, the same air that helped him

get up here gives him a new challenge.

As he powers forwards, the air pushes him back,

a force known as drag,

slowing him down and reducing the lift in his wings.

By beating his wings, he creates a constant source of power

to maintain air speed.

Without this thrust, he would soon slow to a standstill...

..and literally drop out of the sky.

So swans must keep flapping,

all the way to their new feeding grounds.

All flying animals have to wrestle the powerful conflicting forces

of gravity, lift and drag,

but the faster they go, the thicker the oncoming air feels,

and drag becomes an ever bigger problem.

So what if you're one of the fastest animals on the planet,

and you're moving at more than 320 kilometres an hour?

The peregrine falcon.

Its breakneck speed gives it the edge to surprise

and strike its prey with devastating force.

It's spring here in California,

and a pair of peregrines has a new family,

and with it, a new problem.

At four weeks old, each ravenous chick eats more than an adult,

so both parents need to hunt successfully every day.

Feeding their growing youngsters is a full time job.

So what is it about peregrines that makes them

so much faster than almost any other animal on the planet?

They've got flying at speed perfected,

down to the tiniest detail.

See-through eyelids stop their eyes drying out...

..and specially shaped nostrils

slow down the air to make breathing possible at high speed.

When off on a hunt,

a peregrine uses updrafts from the cliff face to gain height.

Up here, it can spot potential prey.

And when it does, it starts a specialist dive,

known as a stoop.

A few deep wing strokes help it accelerate

to 190 kilometres an hour.

At this speed, oncoming air smashes into every part

of the peregrine's body, slowing it down.

By tucking in its wings, the falcon can slip through the air

that much easier

so now 240 kilometres an hour becomes possible.

But the faster you go, the more of a problem drag becomes.

At top speeds, every bump on a bird's body will disturb the air

flowing over it,

and this turbulence slows the peregrine down.

But that same turbulence makes special feathers pop up over

the peregrine's back,

and this pulls the air back into line

so it flows smoothly over its body again.

With drag minimised, peregrines can top 320 kilometres an hour.

At this speed, they can cover the length of a football pitch

in only a second.

This sheer, unadulterated speed makes them masters of aerial attack.

Top-gun skills allow these falcon parents to keep their chicks fed.

But these same skills also allow them

to protect the chicks from anything they think might attack the nest.

They really don't like intruders.

At the slightest hint of a threat,

the falcons will scramble and intercept in seconds.

The falcon may be smaller and less powerful than many of her targets,

but pure speed gives her the edge to harass

and then escape before they can react.

Pelicans are ten times her size,

and here's a whole squadron of them.

But size is no match for precision, high-speed flying.

Each attack aims to disrupt the pelican's own flight.

Just jerking their head to one side is all it takes to send

the pelican out of control.

Meanwhile, her own high-speed, top-gun skills

keep her out of harm's way.

Speed helps a peregrine mother own the skies around her nest.

But what if you're a high-speed hunter

and you don't have big, wide open airspaces to fly in?

What if you lived in an English country garden?

Flying fast, close to the ground,

and around a veritable assault course of obstacles...

..there's a skilful hunter that does just this.

Meet the master of high-speed aerial agility - the sparrow hawk.

As his name suggests,

this pocket-sized predator hunts small birds,

using surprise as his strategy.

And this is how it works.

The targets are right in the middle of a garden over 50 metres away,

with escape routes in all directions.

He'll need to use as much cover as possible to hide his approach.

And by knowing every tree and shrub in his territory,

he can pick the perfect route -

skimming hedges

and hurtling through the undergrowth to maximise the element of surprise.

But there could be 20 pairs of eyes on the lookout.

And if any of them spot him, they'll sound the alarm.

Nine out of ten sparrow hawk hunts fail because of this,

so he's got to be fast and agile,

and strike in just four seconds.

Few flying creatures can do this.

But then few have the sparrow hawk's supreme flying abilities.

He has explosive acceleration.

Long legs fire him out of the blocks.

Short, rounded wings powerfully scoop up the air, driving

his lightweight body forwards

to hit attack speed in under two seconds.

Now at speed, he keeps a low profile, hugging the ground.

This low position gives him an extra advantage.

The air is squeezed between his wings and the ground,

giving him a high pressure air cushion to ride on.

This keeps him airborne and saves valuable energy.

But hurtling along at 50 kilometres an hour gives him

just hundredths of a second to avoid a collision.

Short wings are pulled in to pass through the tiniest gaps.

A long tail does the steering, constantly making fine adjustments.

And when he needs to turn sharply,

he slams on the brakes by fanning it out.

As he gets closer, precision flying becomes critical.

He needs to stay hidden until the very last moment.

The last thing a garden bird might see...is this.

It's all over in seconds.

The sparrow hawk masters the skies with speed and agility,

but what if you have neither speed nor agility?

There's a creature that's so slow and clumsy

many would doubt it could fly at all.

And yet, it performs the seemingly impossible.

The Japanese rhinoceros beetle is covered in protective armour.

In the world of beetles, he's a colossus,

weighing a hefty 10g.

He's on a mission to find a mate, and she could be miles away.

He doesn't have long, and it's too far to walk.

So he has to fly.

But attempting to fly whilst carrying all that heavy body armour,

he's going to need a combination of power and some extreme moves.

So how does such a huge beetle stay airborne?

He has a special flight technique,

very different to that of most birds.

Slowed down, you can see that he twists his wing at the base.

We need a special flight laboratory to see how this helps.

Now we can see just how the air moves around the beetle's wing.

Those mini tornadoes spinning off the wing show where

the beetle is pushing the air back, thrusting him forwards.

And because it's being pushed down, we know he's also producing lift.

So far, that's much like a bird.

But critically, by twisting his wings at the base,

he can also push air backwards as they move back up.

And there's the proof.

This gives him thrust on both the down stroke and the upstroke,

and that's something that most birds can't do.

But he doesn't leave it there.

Even his armoured wing cases are working in his favour,

forcing air down to create even more lift.

So he effectively has an extra pair of wings.

This magnificent beetle is a flying marvel.

His clever wings give him the extra lift

and thrust that he needs to cruise at nearly 15 kilometres an hour.

He's hardly a boy racer,

nor is a he a long-distance flyer,

but he can cover half a kilometre in a night.

And in a jungle, that's enough to find a female.

This huge beetle's flying mission may have seemed impossible,

but it's worth the effort.

Special wings that rotate at the base

allow the beetle to get more from the air around him,

keeping him airborne, albeit, rather clumsily.

But in Central America, there are other creatures who have

taken this to the next level

using this technique to fly in almost any direction

with ultimate precision.

They're not insects but tiny birds.

Hummingbirds, each the size of your little finger.

To the human eye, their flight is no more than a blur.

It's only when slowed down 50 times you can appreciate

their incredible control.

So, why are hummingbirds so special?

This is one of the world's most spectacular flyers,

a booted racket-tail hummingbird.

On the face of it, he's got it made.

Here in Ecuador, his forest home is full of flowers,

each with sugar-rich nectar hidden inside.

But he has a problem.

These flowers don't provide perches,

neither do they make nectar easy to get at.

Now the hummingbird's extraordinary flight technique starts to

makes sense.

It hovers so it can move its needle-like beak into position

with surgical precision.

Running down the inside of the beak,

a forked tongue laps up the nectar at up to 13 times a second.

But just performing a simple hover breaks all the rules

of traditional flight, so how does he do it?

It's a technique similar to the beetle's,

but impossible for other birds,

and requires a very special pair of wings.

They're short and stiff to cope with the stress of beating

at up to 80 times a second.

But it's how a hummingbird beats its wings that allows it to hover.

On close inspection, the wing tips move in a figure of eight.

A unique wrist joint means the wing can rotate through up

to 140 degrees...

..so he can thrust air down and back

not only on the down stroke but also on the upstroke.

That gets him hovering.

By having constant power, he can also make tiny adjustments

throughout the wing beat, and this gives him more control.

Added precision comes from the way he rolls his body,

instantly changing the angle he's pushing at.

With incredible wings like these, he can fly forwards, left,

right, even backwards.

This gives him the power and control he needs to get at the nectar

and move between the flowers.

But this super powered flying ability comes at a huge cost.

A thermal camera shows just how much heat is given off when hovering.

This heat is just a fraction of the energy that a hummingbird

needs to stay airborne.

Hovering burns far more calories than any other form of flight.

To provide his muscles with enough oxygen,

his heart has to beat at 20 times a second,

and he needs to drink his body weight in sugary nectar every day.

In fact, this tiny little bird has the highest metabolism

of any warm-blooded animal.

So our hummingbird might have the ultimate control in the air,

but he'll always be a slave to his uniquely manic lifestyle.

Trapped in a world where he needs to hover to feed

and needs to feed to hover.

Hummingbirds can afford a high-energy lifestyle

because food is always close by.

But what if your next meal is hundreds of kilometres away

and you have to go searching for it?

You're going to need a completely different flight technique.

Patrolling the ocean around South Island, New Zealand,

this is a royal albatross.

Albatrosses spend the vast majority of their lives out at sea.

The one time they need land is to nest.

This albatross is providing for one of the world's biggest chicks.

At two months old, her chick will eat half a kilo of fish

and squid in a single sitting,

so she'll have to travel far and push the limits of flying.

She's chosen to nest on this wind-blasted cliff

for a very good reason.

To take off, she spreads her three-metre wings,

and the cliff top wind provides the lift.

Ungainly on land, she is now in her element.

Out here, fish and squid can be extremely difficult to come by.

So a mother albatross will scour the ocean

for up to 1,000 kilometres a day.

During her lifetime,

she'll travel nearly two and a half million kilometres.

That's to the moon and back three times.

And remarkably, she can do this with barely a wing beat.

She's one of the world's most efficient fliers,

using the energy of the air just above the ocean

to save her own energy.

She's riding the air like a rollercoaster,

in a super efficient way.

But snaking from side to side like this

seems to make no sense at all

until you understand how air behaves above water.

At the water surface, the air collides with the rough waves,

slowing it down to a virtual standstill.

But ten metres above the waves, the air flows that much faster.

It's this difference in air speed that allows the clever albatross

to fly for free.

By sweeping up and down, she can use both the fast air

ten metres above the waves

and the still air at the water's surface.

And here's where the sheer efficiency of those long,

narrow wings is so important.

As she climbs into the faster wind,

she can create more and more free lift.

Then with height on her side, she turns sharply,

and a combination of gravity and wind now slingshots her downwards

up to 120 kilometres an hour.

Known as dynamic soaring,

the ability to use changes in air speed like this

means that albatrosses rarely need to flap their wings.

This energy-saving technique allows them to travel

huge distances to find food in the open ocean.

And when you're a mother,

scraps from a fishing boat are too good an opportunity to miss.

Now full of food, an albatross's next challenge is to get home again.

But unlike before, when she could wander in any direction,

she must now fly directly back to her chick,

even if that means heading straight into the wind.

Once again, she reads the air in front of her

and uses its movement to her advantage.

Albatrosses use a special organ hidden inside their nostrils

to constantly measure tiny changes in air speed.

This guides her to pockets of still air behind each wave.

Flying is much easier here.

And when she needs extra lift,

she can even seek out upwards moving air that flows over each wave crest.

This way, she can fly all the way home really efficiently,

even against the wind.

The chick gets fed because its mother can read the air

and ride it effortlessly.

In six months, it will be doing the same.

The albatross's ability to fly far in search of food allows it

to exploit the patchy resources of the Southern Ocean.

But they aren't the only creatures

that survive by travelling huge distances.

Others move with the seasons,

flying between winter and summer homes,

in the biggest journey of their lives.

Migration.

Over thousands of kilometres,

across countries, sometimes even entire continents.

Insects, bats and birds all make these journeys to find food,

and breed as the seasons change.

These are some of the toughest physical challenges

any animal undertakes.

Many die en route, and exhaustion is the biggest killer.

So any way that you can save energy might save your life.

There's one animal that that flies with incredible efficiency,

not on its own but as a team.

European cranes migrate nearly 3,000 kilometres every year

between their wintering grounds in Spain

and their summer home in Scandinavia.

These cranes travel together as a family,

with the chicks learning from their parents.

It's how they fly as a group that's going to give them

all a crucial advantage on their long and arduous journey.

Adult pairs mate for life,

and they dance together every year to strengthen family bonds.

THEY WARBLE

This is no frivolity.

How they bond and work together might make the difference

between life and death, particularly for the youngsters.

To understand how teamwork helps them,

we need to see the world from a crane's perspective.

Cranes are relatively large and heavy birds,

yet they'll fly multiple marathons in just one day.

This burns a lot of energy.

Like albatrosses, they're going to have to fly efficiently

if they're going to make the distance.

But unlike albatrosses,

cranes can't rely on saving energy by soaring all the time.

To make this journey,

they will need to flap their wings hard...

..so they make every flap count by working together,

and that means formation flying.

All crane species will fly in the same ingenious way.

Each flock member flies

slightly behind and slightly to the side of the bird in front,

creating a characteristic V shape.

But each bird must be positioned exactly

if the teamwork is going to pay off.

To understand why, we need to see how the air moves

around a crane wing in flight.

Each bird leaves a wake in the air behind it.

A tube of spiralling air trailing behind the wing tip

still contains energy from the bird's last flap.

If the bird behind gets in the right position,

it can use the upward motion of the spiral to keep itself up,

and therefore save its own energy.

So one flap can be used by more than one bird,

they're literally sharing the load.

Formation flying could save each bird in the team

over 10% of its energy.

On a long migration, this could make the difference

between success and failure.

The leader of the V formation has to work the hardest,

with no energy to inherit from the birds in front of it,

so the cranes take it in turn to lead

and share the work around the team.

They also share their knowledge.

Youngsters learn the migration route from their parents,

so eventually they'll be able to lead a family of their own.

Cranes may not be the strongest or the fastest flyers,

but their technique as a team

gets them to their breeding grounds each year.

Formation flying is used by many birds,

it's an energy-saving trick that makes long distances

that little bit easier.

Many flying creatures have one particular flying skill that

gives them an edge.

But perfecting one skill means you might not be so good at others.

When you're built for speed, it's difficult to be an acrobat.

Amazing acceleration burns energy,

but that's no good if you're a long distance flyer.

And if you need to power a large body into the air,

being manoeuvrable becomes more of a challenge.

It can work to be a specialist,

but what if you need to be good at everything?

What if you need to combine many different flying skills

into the ultimate flying machine?

There are some creatures who've done just that.

They aren't birds, they aren't bugs - they're mammals.

Dawn in Texas,

and half a million Brazilian free-tailed bats

are returning home after a night out feeding.

During the next few seconds,

their flight skills will be pushed to the limits.

For these aerial masters, the last part of their journey is

the most dangerous.

Predatory hawks are waiting.

The bats are heading to the safety of a cave.

Their challenge is to completely change the way they fly

more than once.

First fly fast,

topping a 100 kilometres an hour.

Next, hit the brakes as they fly into the pitch dark.

Finally, fly alongside the half a million other bats in the dark cave.

Now it's about being manoeuvrable and trying to avoid collision.

Within a few seconds, the bats have to perform a range of completely

different flight techniques, each of them highly specialised.

This requires incredibly versatile responsive wings.

Bats do something unique in the natural world.

They fly not with their arms but with their hands.

A bat's wing is a miracle of flight engineering,

complete with thumb and four fingers and self tensioning skin in-between.

Its shape can shift in all three dimensions

and far more than any bird or insect.

No other wing gives this level of control.

Innovative wing design allows the bats to cover huge distances

to feed,

fly fast to evade predators

and manoeuvre tightly in their crowded cave.

This expert flying ability allows the bats to use the caves

as giant underground nurseries.

Hundreds of thousands of baby bats huddle together for warmth.

In here, all bats are as safe as they're ever going to be.

But for the adults, that's about to change.

Outside, dusk is fast approaching, so soon the adult bats

must leave the cave again to feed for the night.

But the hawks are waiting.

The hawks can't see in the dark,

so every second the bats stay underground gives them an advantage.

But sooner or later, each bat is going to have to

push its flying skills to the limit once more.

Their strategy is to emerge together giving safety in numbers -

an incredible feat of synchronised flying.

More bats swirl up from deep underground

until the cave entrance is full to bursting point.

With their wings now outstretched, they can build up speed.

Tens of thousands of bats,

all waiting until the last possible moment.

With deep powerful wing beats,

the bats can accelerate through the danger zone.

The hawks are overwhelmed by their sheer numbers,

their manoeuvrability and their speed.

Now safely away from the cave,

they're free to fly as far as they need

to their night-time feeding grounds.

A radical innovation in wing design,

flying with their hands

has made bats perhaps the most versatile of all flying animals.

They're the only mammal to have truly mastered life in the air.

For all flying creatures, staying airborne is a constant challenge.

A life in the air requires special skills and remarkable techniques.

But if you can survive up here,

there are huge opportunities to be had,

so every animal has its own strategy to give it an edge...

..as it masters the sky.

In Life In The Air, the team's mission was to reveal the incredible

abilities of airborne animals in more detail than ever before.

Weeks of patient filming allowed the team to capture real-life events,

like peregrine falcons attacking their animal neighbours.

But to reveal the science behind how these animals master the skies

required additional filming tricks

and some incredible individuals who would allow the team to capture

their unique behaviour...

..impossible to achieve in any other way.

To film the planet's most accomplished flyers,

the team needed to become part of their flock.

Key to their success was a unique relationship between the animals

and the people that work with them.

The more ambitious the shoot,

the more important this relationship becomes,

and none presented a bigger filming challenge

than keeping up with four tame whooper swans in Scotland

and flying alongside a family of European cranes

high above the French countryside.

First meet Olive, Earther, Yellow and White,

and their human mum, Rose Buck.

If their mum's here...

When the swans first hatched nine years ago, the first thing

they saw was Rose, so to them, she's the leader of the flock.

Rose and her husband, Lloyd, have a close bond

with over 20 different bird species...

Oh, yes.

..all film stars in their own right.

And whilst the swans are on centre stage this time,

the whole family comes along for the ride,

including a golden eagle called Tilly.

Basically, when we go away, they all have to go with us

because they're like our extended family,

and that's when they're at their happiest.

You wouldn't leave your children behind if you went away,

so they expect to come with us.

The Buck family are heading to Loch Lomond in Scotland,

where the plan is to film alongside the swans in their natural habitat,

capturing their flight in minute detail.

At the heart of this immense technical challenge is

a state-of-the-art stabilising system,

to smooth out any bumps in the water...

..and a high-speed powerboat that can top 65 kilometres an hour.

After some final words of encouragement from Rose,

it's time to put the plan into action.

Let's go, go, go!

With Rose at the bow,

the swans are totally unfazed by the speeding boat,

which is more than can be said for the director.

It's a really difficult thing to do when

something as amazing as this

to be thinking about your job and the shots,

cos it's utterly awe-inspiring.

Without an image stabiliser, it's virtually impossible to get

a steady shot at speed.

Cameraman Rob Drewett has the advantage of the stabiliser,

but wind gusts are causing him unexpected problems.

-Uh... It's gone.

-What's happened?

As the boat hits 65 kilometres an hour,

the stabiliser really starts to struggle.

As soon as I took it away from my body,

you...you felt the wind take it.

The elements aren't beating the stars,

but they're causing big problems for the technology.

Ah, it just died.

-We've got a bit of a problem.

-Yeah.

When you're pushing the limits of filming technology,

sometimes you really need to think on your feet.

We're now having to go to new extremes to try and get

our equipment working well,

and we...we're going to use a dustbin!

With a rather unorthodox wind guard taking shape,

there's nothing the Buck family can do,

except indulge in some family time.

You wouldn't want to be skinny dipping!

Gor, struth, you wouldn't.

Meanwhile, the camera crew work on into the night.

It's the last day in Scotland, and the crew have their hopes

pinned on a £15 bin shielding a £50,000 camera system.

This is the 11th hour,

it always seems to boil down to the last day, but that's all we've got.

Now everything needs to come together in one perfect run.

Lovely.

So it looks like the shroud is doing the job, which is

brilliant cos it took us two hours last night to turn

a dustbin into something that can make us film swans.

Look at this! Oh, wow!

Filming flying animals at speed has proved difficult enough on water...

..but it's that much harder when you take to the air

with a flock of European cranes half a mile above the Earth.

To get a true bird's-eye view, you need a microlight,

a pilot with a family of friendly cranes

and a cameraman with a head for heights.

Like Rose is mother to her swans,

Frenchman Christian Moullec knows each of his family by name.

-Is this Dennis?

-No, no, no. Dennis, no.

THEY LAUGH

Christian has been working with these particular birds

for two years, so when the microlight engine roars...

..they know it's time to fly.

The cranes follow the microlight in formation,

using the updraft from its wing to save energy.

They're performing perfectly,

just in completely the wrong place for cameraman Richard Cook.

Getting them away from the wing and into the right spot requires

precision teamwork, and this is extremely difficult.

The birds move around so much, so quickly,

and then just trying to guess where they're going to be.

So they drop off the wing here and they come down

and then underneath the aircraft, up the other side.

It's very frustrating, but we will get there.

-Christian.

-Yes?

-Your birds are terrible!

No, you are a terrible cameraman.

RICHARD LAUGHS

With something this complicated, there's no substitute for practise.

But the longer you're in the air,

the more chance something very serious will go wrong.

The engine has cut out, and with no power,

Christian and Richard have to make an emergency landing.

It's at times like this that 25 years of experience comes

sharply into play.

On the final approach, they are fully committed.

Thankfully, it's a perfect touchdown.

And the cranes don't seem to know what all the fuss is about.

We landed safely, just glided in, but there's not a lot we can do.

As you can see, this is absolutely jammed solid.

So we're going to take the engine apart this afternoon

and see what's broken.

In the middle of the French countryside, any rescue,

however unusual, is extremely welcome.

Just looking at the top, the piston crown,

the bit at the top, is all hammered and dented.

Anyway, it's given up.

The engine isn't repairable,

so the team resort to the backup microlight.

And with it comes a new dose of luck.

With some perfect turns from Christian,

Richard finally gets eye-to-eye with a flying flock of cranes.

And after all they've been through, the team are truly delighted.

But even with the latest technology

and some resourceful individuals, we only get the briefest window

into the world of these amazing creatures.

And this only highlights just what an achievement it is

to spend your life in the skies.

Next time, we'll discover that the skies are crowded

full of creatures in a battle for survival.

There's competition for mates,

for food...

..and even for life itself.

Only the best flyers need apply.