Original subtitles

The ability to move through the air in any direction you wish,

to cross continents and oceans,

to range over forests and deserts and mountains,

all this birds have been able to do for 150 millions years.

But they won't the first or indeed the last in the skies.

We are setting out to explore one of the most astonishing stories in the natural world.

The way in which animals manages to rise up from the surface of the Earth,

and colonise the air.

From the dazzling aerobatics of the insects...

to the majesty of ancient winged reptiles.

The splendor and agility of birds...

and the sonar guided precision of night flying bats.

Flight has been the key to the success

of some of our Planet most remarkable inhabitants.

To analyze theirs spectacular skills, we will use the latest technology.

And we will travel around the world.

From the jungles of Borneo to the fossils filled rocks of China.

And the Cloud Forest of Ecuador.

We will take you into the air...

and travel with animals as they fly.

~ Conquest Of The Skies ~

THE FIRST TO FLY

Evidence for the very beginning of this astonishing story

can be found close to home in The Fens of Cambridgeshire.

Here live creatures that have ancestry stretching back millions of years.

Nobody know exactly how the first flying animals in the world evolve,

but there are creatures alive today, that can take us back

to those far distance remarkable times,

and they live surprisingly under water.

Looking down through the surface to the riverbed,

is like traveling back in time over 320 million years.

It was then, in an age long before even the dinosaurs evolved,

that creatures like this first appeared in the waters of the Earth.

It's an insect.

A ferocious predator with jaws like a mechanical grab.

It seems unlikely that this animal ancestors

were among the first creatures ever to fly.

But this one is not yet adult, it's a larva,

and it doesn't spend all his life in the water.

It has another life and another body above the surface.

Early one morning it climbs up a reed.

A split appears in its skin, and a very different looking creature begins to emerge.

It has four lumps on its back, that might perhaps ancestry

have become either gills or protective armor plates.

But now they develop into something very different.

Wings.

It has two pairs of them.

Liquid from its body is pump-down along veins to stretch them tight.

As they dry in the sun, they harden.

The watering dragon has become the Dragonfly.

And the four wing depurates that he uses to get into the air,

is the earliest that we know.

Imprints of such wings, have been found in rocks that was lay-down

on the bottom of ancient lakes and streams.

This specimen is about 150 million years old.

And this wing is double age at nearly 300 million years old.

Ancient and modern wings share a structure that is strikingly similar.

So today's Dragonflies are amazingly living fossils that can show us

how the very first flyers overcame the pull of gravity, and took to the skies.

Their wings are marvels of natural engineering.

But to see how they lift the Dragonfly into the air,

we need to slow the action down.

In principle, it looks very simple, each wing beats-down,

pushing on the air below, so lifting the Dragonfly up.

But each beat also creates another air current

that lifts the Dragonfly in a very different way.

And I can demonstrate it, using this strip of paper to represent a wing.

If I blow across the top of it, it will rise. Watch.

That is because the faster air moves, the lower its pressure.

So I created a lower pressure above the wing,

and in consequence it was sucked upwards.

The problem for a flying animal, is to recreate that difference in air speed.

The way the Dragonfly does this is remarkable.

As it moves through the air, we can see that it twists its wings at different angels.

On the powerful down-beat, it holds them at a slight upward angle to the air flow,

and this produces an extraordinary effect above the wing.

It create a swirl behind the leading edge, which spins the air round,

increasing the speed of the air current over the top of the wing.

And with just a tiny increasing speed generates a significant upward force.

Lifting up the wing and the Dragonfly.

The Dragonfly can then change the direction of its wing beats

to propel it forwards as well as upwards.

Remarkably, a Dragonfly can beat each of its four wings independently.

And that enable it to perform an astonishing variety of maneuvers.

It can hover.

It can glide.

It can even fly backwards.

For maximum power, it beats both pairs together,

and can make really sharp turns.

So the very first Dragonflies were able

to extend their territories far and wide.

And as more insects joined them in the skies,

the Dragonflies had the skills to be deadly aerial hunters.

The ability to fly brought great advances to those early insects.

It enable them to find food, to escape from predators,

and particularly important, to travel to new territories in search of a mate.

Damselflies like their close relations Dragonflies,

have remained virtually unchanged for millions of years.

Mating can be quite complicated when both partners can fly,

and these were among the first kind of animals that had to deal with that problem.

The blue color of this one shows that it's a male.

To attract a female, a male must have something to offer her. A territory.

He chooses a stretch of water, that is likely to contain plenty of food for his offspring.

Then he guard this territory against any rivals.

Until a female flies in and joins him.

He must now grab her before she changes her mind, in mid air if necessary.

He uses Claspers at the tip of his abdomen to grip her behind her neck.

Amazingly, the pair are able to coordinate the beats of their eight wings.

They may mate in the air, or choose a secluded patch where they be safe from predators.

They then fly around the territory, laying their fertilized eggs.

Flight enable insects to invade part of the Planet

that until then had been uninhabited. The air.

And they flourished.

So, 320 million years ago the skies flaunt with flying insects.

But those early four wing forms were destined to produce

a all range of spectacular highly specialize flyers.

The need to lay eggs in water, tied the first Dragonflies

to streams and ponds like these.

But then around 20 million years after their arrival,

a new kind of flying insect appeared with no such ties to water.

Proof of their success can be found almost wherever you look

and few places more abundantly then in Borneo.

The very first flyers had two pairs of wings,

now we looking for their successors.

One group of creatures adapted that original

four wing design with such success,

that they diversified into the most numerous

and wide spectrum of animals on the entire Planet,

and you can find some of the most spectacular examples down there in the rainforest.

Not all insects are hunters, some are strict vegetarians like this one.

This it is the land living equivalent to that underwater monster,

the Dragonfly larva.

But this larva instead of catching little fish and water fleas, munches wood pulp.

The trouble is that wood pulp is not very nutritious,

and this creature, has to eat it for at least a year,

before is this size, which is full grown.

But then this larva will turn into an adult, which is equally monstrous.

Emerging from beneath the ground, where it is lived and fed as a larva, is a beetle.

One of the biggest in the world. The Atlas Beetle.

Males like this one are armed with long horns,

powerful weapons with which to compete with rivals for a mate.

It now spend most of his time above the ground,

margined its way through the undergrowth, where it feed on tree-sap and fallen fruit.

This hefty powerful creature may not look as if it could fly.

But it can.

At key moments in its life he takes to the air

to look for new sources of food, and of course, a female.

Alls burrowing and munching around could injure delicate flight wings,

so beetles have harden the front pair

to form this pair of protective covers,

and the delicate flight pair are stored away in safety underneath.

To see how the wings are folded away beneath their covers, we need to wait for take-off.

As it flaps, sprung hinges click-open and the wings are stretch to their full size.

The working wings create lift in just the same way that the Dragonfly wings do,

and the front wings, protecting them as a covers, are held out to the side.

And their shape does give a little extra lift.

So it clear that this is a really are all clumsy flyer.

Landings can be clumsy too.

And now those fragile wings must be carefully packed away beneath of their covers.

They guided by align of tiny hairs of the base of the abdomen.

These grip the wings and help push them into position.

The beetle does it with all the care and precision

that a skydiver uses when packing away his parachute.

Once in a new territory, it will stake out a fresh source of food,

and then defend it until a female arrives.

The beetle way of life proved astonishingly successful.

There are over 370,000 different species of beetle so far discovered.

Unbelievable figure.

So early on, the beetles manage to fly as much as they need to,

with just one pair of wings.

And then around 57 million years ago,

came another key development in the history of flight.

A new type of insect appeared with two pairs of wings

that became in effect huge billboards.

Wings that are perhaps the most dazzlingly beautiful of all.

Butterflies.

To create these extraorinary wings the butterflies evolved complex life cycle.

They hatch some eggs, as little worms with legs. Caterpillars.

But unlike many beetle grubs, caterpillars find their food above ground,

where they are very vulnerable to predators.

So they have evolved several strategies

to accumulate all the bodymass they will need to become flying adults.

First is to eat as much as they can as quicly as they can.

Many are able to reach full size in just a matter of weeks.

Of course, little thin skin fat filled sausage

is attempting morsel for any bird or reptile.

So caterpillas have to have a ways to defending themselves.

This one, which is the caterpillar of lovliest swallowtail butterfly

has disguise itself as a bird dropping.

If that does not deceive of bird and bird goes for it,

it has another form of defense

It's emited rather unpleasant smell aswell.

In the struggle to survive long enough they become winged adults,

other caterpillars have developed other equally ingenious forms of defense.

Consealed with in these fluffy strands are short stinging spikes.

And this one is armed with long spines which have really painful stings

Not only that, it has this warning colours

to tell any potential predator that they will be in trouble if they attack.

This caterpillar my appear to be dangerous, but it is in fact, fraud.

The spines don't sting at all.

It's relying on its disquise to make a potential predator think twice

and leave it alone.

Or, you can simply hide.

These little tents have been made by the caterpillars of a skipper butterfly.

Each caterpillars started by making a circular cut in the edge of the leaf,

but it's left one segment uncut. So them act as a hinge.

Then it pulls over the whole segment

and hides beneath the munch way of the tissues of the leaf.

And if I just pull it up, there are caterpillars.

Caterpillars that survive these hazardious stages,

can now build their wings and turn in to adults.

They undergo truly radical transformation.

Instead of shading of final larvae skin as the dragonfly does,

a caterpillar first surrounding itself with a protective shell.

To act as a sort of changing room.

Within which it dismantles and then completely reconstructs it's body.

After around 10 days it emerges as a butterfly.

Now fluid pumps along veins and wings to stretch them out to the full size.

And then it is ready to fly.

Butterflies live on nectar which they collect from flowers.

Like Dragonflies and Beetles they also fly to find a mate.

But the way they beat their colorful wings is significantly different.

This lovely creature has two pairs of wings,

but he has in effect turn them into one.

It done that quite simply, by overlapping the larger front pair over the smaller hind pair,

so when the front pair beat-down, they automatically press down lower pair.

The lower pair themselves don't have the muscles to beat-down,

but just enough strength to return up.

A Butterfly's overlapping wings compare to the size of their bodies, are enormous,

around 10 times the size of other insect wings.

Because the wing is larger, each beat can generate a huge amount of lift.

So to stay in airborne, a butterfly need to flap less often than other insects.

But that slow wing-beat, also enable it to make rapid and unpredictable changes of direction.

And that allow Butterflies to fly in that zigzag erratic way,

which make them so difficulty to catch, if you are butterfly collector,

or more importantly, a predator.

The combined front and hind wings of butterfly, not only constitute

very effective flying mechanism, they can also carry messages.

In fact, they carry some of the loveliest advertisements in all of the Animal Kingdom.

Like for example, this beautiful Golden Birdwing Butterfly from Borneo.

The butterfly huge wings provide auspicious canvas

on which they display fantastically elaborate designs.

So, how are these flying advertisements created?

The secret lies in the microscopic structure of the wing surface.

These oval lapping scales lined up like tiles on a roof,

have evolved from bristles that were once tiny sensors.

Some contain tiny package of pigment that give the wings color.

Others have a complex structure which split the light,

so that when viewed from a particular angle, it reflects a brilliant iridescence.

There are over 18,000 species of butterfly around the world,

and each has wings with their own distinctive design.

These ravishing colors and delectable patterns, of course,

enable a male butterfly and a female butterfly to know

whether or not they belong to the same species.

And a mature adult ready to mate,

can identify suitable partner from surprising distances.

When a male and female eventually meet, they flutter around each other in a ritual dance.

Each is checking out the flying skills and wingspans of the other.

If both past the test, they mate.

The sheer size of butterfly wings, might seem to condemn their owners to a slow,

almost dawdling flight.

But they can be much more efficient aeronauts then you might suppose.

Butterflies may not be able to fly very fast, but astonishingly,

for such frail looking creatures, they can travel for hundreds of miles in search of food.

New discoveries are revealing that butterflies make immense journeys,

and one of the most exciting of this studies

is taking place 7,000 miles west of Borneo, in Europe.

I am joining a research project in Central Spain,

to look for one of the greaters of all butterfly travelers.

The Painted Lady.

Every spring, Painted Ladies appear in Spain in great numbers.

But Spain is just a stopover.

An international team of scientists are uncovering evidence

of an astonishing journey right across Europe and beyond.

This hugely ambitious project is the brainchild of Dr. Constantise Iovanescu.

Detailed records of when and where Painted Ladies appear

have revealed an extraordinary mass migration.

We were able to collect a huge number of observations

from a more then 60 different countries,

and maybe 35,000 records... - Really?

in many people contributing their observations,

and for the first time it was possible to understand

the general pattern of migration all around.

By combining this wealth of data the team are revealing a route map

that spans incredibly distances.

And it begins in North Africa.

Large numbers of Painted Ladies breed in Morocco over the winter,

before setting out across the Mediterranean to Europe.

They then follow the spring bloom north, as the plants

that they and their young feed on, sprout leafs and flowers.

In summer, they appear in Britain and Scandinavia.

But no individual butterfly lives long enough to achieve this huge journey by itself.

Each step is taking by a new generation.

So, this Painted Lady in Britain is the grandchild

of a butterfly that set out from Morocco.

But then, in autumn, all the Painted Ladies vanish.

Do they simply die out? Or could that be a return leg to their epic migration?

Searching for an answer to this mystery, has given the project

its most astonishing revelation yet.

And it comes from a part of the team based at

Rothamsted Research Institute just outside London.

The key discovery emerge from a surprising source. Radar.

Our radar has a vertical pointing beam, and it illuminates a narrow column of the sky above,

like shining a powerful spotlight up at in the sky,

and we are able to detect individual insects as they fly through that beam.

The signal is so detailed it can even help identify the species.

And during the autumn disappearance,

the radar picked up large numbers of Painted Ladies.

They won't dying out, they were on the move,

and they were flying at astonishing heights.

What we find was, that in fact the Painted Ladies were highly abounded,

at heights of three, four, five hundreds meter above the ground.

At this great height, they were invisible to observers down below.

This explained their disappearance.

But the Butterflies had their own very good reason to travel at such altitudes.

One of the benefits of flying at three or four hundreds meter above the ground,

is that the wind speed-air much faster than the air ground level,

so the insects are able to get a lot of assistance from the wind,

and travel much faster then they would in their own powered flight,

and we see these Painted Ladies traveling at 50 or even 70 km an hour.

As well as measuring the phenomenal speed of their flight,

the radar also revealed its direction.

They were heading south.

So where will they go?

The astonishing answer came from Constantise far-flung network of observers,

and the crucial piece of data was gathered in Africa.

Some expiration in Africa, in October, November,

have shown that there is a huge arrival of Butterflies at that moment. - Really?

So, by the end of the summer, the newborn Butterflies in Europe

are start to migrate a little way back to Africa.

Really? - Ya.

A final generation riding on high altitude winds makes an immense journey

of up to 3,000 miles to West Africa, in just a matter of days.

Observers on the ground, and radar in the air,

had found proof of an amazing migration cycle.

Just in one year the all cycle is made,

and is the succession of these 6 generations moving about

5,000 kilometer in one direction, and 5,000 in another direction.

This migration, is in fact the longest made by

any insect on the Planet so far discovered.

But that raised another question.

How did each generation know which direction in which to fly?

The problem sat scientists once again set out to find an answer.

By tracking the behaviour of Painted Ladies much closer to the ground.

This is our flight simulator experiment.

What we are done is we've.. butterflies to find road.

And put them inside these flight simulators.

There are ridged up to computer and the butterflies are free to turn.

And as they turning, we recording that turning,

and we can acctually draw out the flight path they would've taken if they free flying.

Tha barrel blocks the butterfly's view of surrounding scenery

removing any possible distractions.

The only reference point they have is the sky above.

Remarkably the butterflies consistenly choose a common direction.

These are the flight headings each spot is one individual butterfly

and the overrule direction they went in.

So you can see that on average my butterflies were flying to South.

What we found, when we put a lid on simulator so they could not see the sky,

is as you see they did know in which direction to go.

They would not able to maintain southwest heading.

Rebecca concluded that their ability to choose this heading

must depend one thing they can see in the sky above.

The Sun.

Actually the sun is really good cue, it is very predictable and is movements accross the sky.

And butterflies will be flying in the middle of the day when there is warm

until the Sun is out and this must be a South at that time of the day.

So it is very good sign for butterflies to know which way is South.

These inbuilt compass allows Painted Ladies

at tight altitude to select a wind which heading South.

So it is a free ride at long return jorney all the way to Africa.

Some insects face a very different challenge, not fly long distances,

but flying in the dark.

A Light Trap can attract some of the most remarkable of this nocturnal flyers.

Moths.

Moths probably evolve to fly at night to avoid predators.

Their eyes are adapted to low light, but they also use a second highly develop sense, smell.

This is a male Moon Moth.

Moths overlap their two pairs of wings in just the same way Butterflies do,

and this particular moth is very special. It has an extremely short life.

He will only live for a week. It won't even feed.

Its only object is to find a female.

And it does that with these remarkable feather-like antenna.

The female emits a particular characteristic scent,

and with those antenna, the male can sense it from as much as a mile away.

He then take-off and fly upwind, until eventually it find the source.

Moths with their combined front and rear wings, are also excellent flyers.

Some live longer, and so need to fly to find food.

This Sphinx Moth favorite food is nectar.

It can even hover as it drinks.

So, by overlapping their two pairs of wings,

Butterflies and Moths has become very competent flyers.

But there is one group of flying insects that has change

the back pair of wings into something quite, quite different.

Something that enable them to perform the most extraordinary aerial gymnastics.

For the final chapter in our story of flying insects, I'm returning to London.

The urban jungle and its human inhabitants provide plenty of shelter and food

for a particularly adaptable and numerous kind of insect.

Thank you very much. - Thank you.

An inviting meal like this one, well, I'm quite sure,

very soon attract a flying diner, that is one of the most remarkable

of all insects aeronauts.

It is of course a Fly.

This particular kind, a Blow Fly, occurs all over the world.

And its ancestors have been buzzing around for a least 250 million years.

Flies are so common, we tend to dismiss them as just irritated pests,

but their flying abilities are truly remarkable.

Watch what happen if I try and swat this one on the menu.

Slowing down the action by 40 times, we can see how astonishingly agile Flies are.

It make its escape in the time it take me to blink my eye.

The ability to twist and turn at such high speeds, and so evade enemies,

has made Flies the global success that they are.

They are the jet fighters of the insect world,

and they owe their maneuver ability not to the shape of their wings,

nor the power of their muscles, but to a set of highly advance flight sensors.

A fly has its own version of a fighter pilot instrument-panel.

Providing constant update on speed, altitude and direction of travel.

A fly gather this flight data through its eyes,

and these on among the best in the business.

They can process visual information around 10 times as fast as our own eyes.

But in high speed maneuvers, even a fly eyes

struggle with one crucial piece of flight data.

The angle of its body in the air, and the way it changes.

Information that a human pilot will get from an instrument based on a Gyroscope.

And that is essential if you going to pull-off a stunt like this one.

Fortunately, Flies not only have eyes to guide them.

They also have a second and even more remarkable set of sensors.

One that it derived from that original four wing design.

A fly only has a single pair of wings.

The rear pair have been converted into something else.

A tiny club-like appendage known as a haltere.

This surprisingly sophisticated organ alert the fly for changes

in the position of its body in the air.

As the fly takes-off, each haltere begin to beat up and down,

and so fast, it immediately becomes a blur.

But in slow motion, we can see that it swing back and forth like a pendulum.

To understand how the haltere works,

we need to track its movement in the midair roll.

The weighty tip of the haltere has a kind of moving in arched,

so, that it remain on the same swinging path as the fly banks.

Now, the angle between the body and the haltere changes,

and the base is put under stray.

This triggers sensors which register the roll.

The fly can then adjust its wing beat to correct any imbalance, however extreme.

New studies into a second remarkably use of the haltere signal

are taking place at London Imperial College.

In the department of Bioengineering, experts are studying Blow Flies

to see if their natural flight mechanics can improve the performance

of man-made flyers, like this drone.

Flies are incredibly maneuverable, and if you look at their performance,

one chasing another one, it's really hardly

any other animal that can match this sort of aerodynamic performance.

Holger has devised an experiment to investigate an intriguing connection

between a fly halteres and it other key flight sensor, its eyes.

A tiny motor simulate a series of high speed midair rolls.

The way the fly then reacts, is recorded on a specialist camera

which can replayed the action in slow motion.

As you can see if you look closely, the head of the fly is maintained level,

the body is rotating, and to maintain level gaze

they have to counter-rotate the head.

Keeping the eyes level is vital, if they to gather accurate flight information.

And the halteres has been identified as the crucial sensor that makes this possible.

Visual system alone will just be to slow, that's where actually the halteres come in.

The halteres are extremely fast in terms of their responses,

and they are immediate will signals, that are then sent to the neck motor system,

and to the flight motor system, they are the first really

to compensate for any disturbances, and if that has happened,

the visual system is perfectly well situated to cope with the rest.

So, Flies lost a pair of wings, but gain an extraordinary new flight sensor

that made them the most advance flyers in the insect world.

Flight has enable the insects as a all to become an astonishing global success.

There are twice as many insects species,

then there are of all other animals put together.

Theirs is a remarkable evolutionary story

that spans over 320 million years.

From the first four wing creatures that emerge from the water,

to the armour-plated Beetles which colonise land away from water.

The Butterflies with their huge colorful wings.

And the stunningly skillful aerobatic Flies.

But skill may not be enough, sometimes sheer size counts.

The insects had the skies for themselves for around 100 million years,

but then a new group of animal appeared, animals that could build bigger bodies,

and they were to lift the techniques of flying to even greater heights.

As our journey through time continues, we encounter

the extraordinary pioneers of a new wave of larger flyers.

Monstrous winged reptiles.

Strange feather dinosaurs, who ventures into the air led to the birds.

And a group of mammals that conquered the pitch-black of the night.

The bats.

Written and Presented by David Attenborough

We human beings are very latecomers to the skies,

and although we might think that we now pretty good at this,

the Natural World, with the help of several million years of evolution,

has produce a dazzling range of aeronauts whose talents are far beyond our.

The story of how animals manage to colonise the air is truly astonishing.

First into the skies were Insects,

they initially had two pairs of wings

which in due course were modified in many different ways.

But after having had the skies for themselves for about 100 million years,

a new group of animals took to the air,

Vertebrates. creatures with backbones.

They faced a different challenge, for their bodies were much bigger and heavier.

But eventually they evolve several ways of solving that problem.

We will travel the globe to trace the details

of the extraordinary skills of the backbone flyers.

~ Conquest Of The Skies ~

RIVALS

This is Borneo.

And here there are still great tracks of pristine rainforest.

Forest that is wonderfully rich in animals of all kinds.

I'm being winch up into one of the tallest trees here,

in search of a creature that can give us a hint

of how backbone animals first took to the air.

Hidden among these leafs of this fern, high up here in the canopy,

is a very remarkable little frog.

It's a Harlequin Tree Frog, and it a very-very good climber.

It spend most of its life up here, clumping around in the branches.

Here it's away from the numerous predators there are,

that might attack it down on the forest floor.

But if in fact, a predator were able to get up here, to hunt it,

a snake perhaps, well, the Tree Frog has a remarkable trick for defense.

It glides.

It has membranes between greater elongated toes,

so that each foot becomes a parachute which slow the frog descent,

and so enable it to make a relatively safe landing.

The Vertebrates made their first forage into the air around 260 million years ago,

and it very likely that some of these pioneers use skinny membranes

to control their falls in much the same way as this little frog does.

It has to be said that is not a very good aerial navigator,

it seems that it just jumps and hopes for the best.

But there are animals up here, that glide around from tree to tree,

which are very good navigators indeed,

so good in fact, that they can go from one tree to another

and never go down to the ground in their entire life.

One of them is a little lizard called Draco.

Each male has his own little territory in the branches,

and tries to attract females and warn off rivals by flashing his dewlap.

He also spread colored flaps of skin from his flanks,

that when fully extended do more or less the same thing.

But there are predators among the branches.

Snakes also live up here, and they hunt Lizards.

But Draco side flaps now serve another purpose.

He uses them to glide by hinging forward a specially elongated ribs.

And he so skilled in the air that he can steer land

on the trunk of his choice.

So, if you live up in the branches it's less laborious,

and indeed, safer to travel by air, than to come down to the ground.

But if you want to be a true flyer, you have to be able to fly

not only downwards but upwards, you have to have powered flight.

This is another reptile,

and one with even greater flying abilities than that little gliding lizard.

Today, sadly, it's extinct.

This is Dimorphodon, we can deduce from its fossils

that he had the muscles needed to beat its wings.

And computer imagery can show us what he must was look like.

Dimorphodon was one of the first large animals ever to travel by air,

200 million years ago.

It belong to a group called the Pterosaurs, The Winged Reptiles.

It was probably a forest dweller and it descendant of a tree living glider.

This gliding ancestor might have had wings like those of Draco,

that was made of skin, and perhaps extended from its fingers down to its ankles.

But Pterosaurs have evolved larger wings with a hugely elongated fourth finger.

The wing membrane was strengthen internally by thin rods of a stiffer tissue.

They were muscles fibers too, that enable it to modified its contours as it flew.

Looking at the wings insection revealed a secret of their efficiency.

They have a rounded front edge and a sharp back edge,

a shape known as an aerofoil.

It's works by forcing the air flowing above the wing, to speed up.

This faster air has a lower pressure, and the wing is suck upwards.

The larger the surface area of the wing, the greater lift it can produce.

So, it seem certain that Pterosaurs were very competent flyers.

And judging from their teeth, it's seem likely that many fed on the great variety of Insects

that had preceded them into the air.

Insects have had the skies to themselves for around 100 million years.

Now, bigger creatures had arrived. Reptiles.

The Pterosaurs design for flight proved hugely successful,

they use that new powers to spread beyond the forests

and colonize whole new environments.

A great number of them lived and fed near water.

We know this because fossils of many species

occur in rocks that was once mud at the bottom of lakes and shallow seas.

This one shows the skeleton of little animal that 150 million years ago

fell to the bottom of a shallow lagoon.

This is its head, here is its backbone,

tail, hind legs,

and here stretching from these long extended finger bones are its wings.

And this fossil is particularly remarkable,

because it show an impression of the membrane in extraordinary detail.

You can see every little tiny fold.

You can judge how an animal lived by its skull.

And this one, have these long jaws,

with forward pointing teeth, and we think that this indicates

that it lived by skimming across the surface of the lagoon,

and snatching up fish with impaled on those teeth.

This, very different one, it's just the head.

As you can see has very long jaws

and on the tip of the lower one is this little tuft of very fine filaments.

We know from other specimens that these filaments

originally stretch right along the entire jaw.

This bristely fringe enable the creature to filter feed, taking in a beak full of water,

expelling it through the bristles with the beak half closed

and then swallowing what the bristles retained.

And here's is a skull of a very much bigger species from Brazil.

And it had neither teeth nor bristles in this jaws.

But microscopic examination of the surface of the bone here

reveals very tiny little blood vessels

and that suggests that this jaw was once covered with horny beak.

So maybe this animal used it's beak like the forceps

to pick up small little reptiles or maybe catch dragonflies in the air.

This particular skull reveals something else about the lifestyle of this specimen.

Because of the back of the scull it has this great flange.

And Pterosaur from other species

have been found some with such flanges but others without.

So it's tought that maybe this was the difference between sexes.

Maybe was the male that had this big flanges backwards to display them.

Maybe was covered with the skin. We can only guess.

Many different pterosaurus species evolved these headcrusts

and seems very likely that they were colored.

This spectacular example is known as Tapejara.

And it made it's home beside inland lakes.

But Pterosaurs diversify another ways too. Some evolved much larger bodies.

This species had a wingspan of over 20 feet, 7 meters.

But not all Pterosaurs lived in the forests or near water.

An open arid landscape like this one, was the likely home

of one of the most extraordinary.

Around 70 million years ago a pterosaur appeared

that was of truly colossal proportions.

That was one of the largest creatures that had ever flown,

it was in the size of a small aeroplane, and it was called Quetzalcoatlus.

Its immense wingspan allowed it to ride on the currents of warm air

that rise up from sun heated land.

It could then glide great distances, searching for food.

Small creatures like lizards, or the dead bodies of much larger ones, Dinosaurs.

But the Pterosaurs, with their wings of toughen skin

weren't the only group of reptiles to make it into those ancient skies.

About 150 million years ago, another reptilian group appeared

on the Planet that also flew.

Like most reptiles, including Pterosaurs,

these creatures began their lives inside an egg.

But they had evolved a revolutionary new design for flight.

One that would usher in a remarkable fresh chapter in our story.

And unlike the Pterosaurs, they still with us today.

There are of course the Birds.

Some today can provide clues about how their ancestors

manage to get into the air.

This is the chick of a bird found in farmyards everywhere.

A Bantam Hen.

And at this very early stage in its life, it can show us something very interesting

about the origin of that crucial piece of flying equipment. A feather.

Its feathers are downy, that to say they made up of simple filaments,

and their function is not for flight, but insulation,

to keep this little creature warm.

And back in the Jurassic period, long before the arrival of True Birds,

very similar looking feathers appeared on very different animals.

Reptiles. Dinosaurs if to be precise.

To find evidence for that astonishing statement,

which not so long ago was highly controversial, we heading for China.

Northeast of China's Great Wall, near the borders of Mongolia,

lies the chilly province of Liaoning.

Here, there are great areas of rocks that was lay down as mud

in the bottom of immense fresh water lakes.

The bodies of animals that was swept down into these lakes

was slowly entombed by the fine grains sediment

that preserved them entire and in exquisite detail.

And from these rocks have come specimens

that solve one of the most hotly debated of evolutionary arguments.

The origin of the Birds.

The key specimens are now in Beijing,

where they been delicately prepared under the microscope.

They have been studied here by one of the world greatest Dinosaurs experts,

professor Xing Xu.

First, he showed me one of his oldest specimens, part of a Dinosaur arm.

But thanks to the finest of the mud of those ancient lakes,

there is more here than just bones.

You see here, this species it called a Beipiaosaurus,

So, because this is a very not like us, two or three meters long,

so quite a big animal. And here is an arm, hand, you see here...

dark filamentous structures... - Yes.

along that arms and hand, they are actually primitive feathers.

And those feathers very simple, very simple,

so we believed they represent the very primitive stage for feather evolution.

These simple strands were made of the same material as the feathers of today Birds.

They were relatively thick and must have been quite stiff,

so they would of stuck out beyond the dinosaur arm.

Behind them, were shorter strands that covered its all body.

Like the down on the chick, these might have kept the dinosaur warm.

But those long strands most likely had a different function.

Clues to what that might have been can be found on an even more extraordinary fossil.

These claws and finger bones belong to a creature called Caudipteryx.

The long dark shapes around them are the remains of feathers.

The single strands are here rather more complex.

They had barbs, thin filaments attached to either side of a central rod.

This look more like a bird feather.

Caudipteryx had around 26 of them along each arm.

This may look like a wing, but the feathers were not very long.

And when you compare them to the size of this creature body, and its long legs, it's clear

that they weren't big enough to enable Caudipteryx to fly.

So, what were these feathers for?

Microscopic examination has revealed that they were colored and patent.

So, maybe they were used for display,

perhaps to wave around during courtship to attract a mate.

But then is seems that they also helped the dinosaur in a different way.

We can find a hint of how they might have done this,

by watching the way some young birds use their first feathers today.

These are ten day old Pheasant chicks.

Their feathers are not yet fully developed.

At this stage they similar in structure to the feathers on that dinosaur, Caudipteryx,

and going aline along each arm in much the same way.

But these early feathers are also too short to enable these creatures to fly.

Nevertheless they very helpful.

Pheasant chicks has to nest on the ground,

but they soon need to roost high up, where they are be safe from predators.

Flapping these simple wings gives the chicks a little extra lift

to help them climb into a tree.

And when the time comes to return to the ground,

those first feathers again are a help.

They don't provide a large air-catching surface,

but they enough to slow a chick fall,

and make that landing just a little softer.

Maybe the feathers that had initially kept the Dinosaurs warm,

now also help them to get into the air.

And then, only a few years ago,

the mudstone of Liaoning produce yet another extraordinary fossil.

It been named Microraptor, and it clearly a small dinosaur.

But this specimen it particularly exciting, because of its feathers.

Feathers on the forearm there.

Feathers on its hind limbs.

And even feathers right at the end of its very long tail.

But there is something that makes these feathers

different from any other feathers you seen on Dinosaurs before.

They are narrower on one side of the quill than on the other.

Just like bird feathers.

Microscopic structures within them suggest that they had flashes of iridescence.

So, these feathers were probably use for display.

But their asymmetric shape is characteristic of flight feathers.

The air flowing over the narrow front of the feather can produce lift.

So, could this strange looking dinosaur with feathers all over it actually fly?

Some people think that those feathers on its hind legs

would have made it rather difficult for it to walk around on the ground,

and that it would had been more at home climbing.

And those claws on the fingers and toes

are obviously very helpful in climbing up tree trunks.

But those aerodynamically shape feathers certainly suggest

that its arms were been used as wings.

This four wing dinosaur must had been a really extraordinary animal.

Its front wings were broad enough to enable it to glide,

and its muscles on the chest were sufficiently strong

to enable it to flap every now and then, and help it on its way.

But the wings on the hind legs were probably not held spread out,

but kept beneath the body to help the animal to steer.

Now, clearly, these Dinosaurs were on their way

to joined the Pterosaurs in the sky.

And then, discovered once again in rocks of China,

creatures recognizable as birds.

This is Confuciusornis. There are two of them here.

They no longer have heavy bony jaws sturded with teeth.

Instead, they have a short beaks made of horn,

without teeth, lightweight.

And the tail is no longer supported by whole chain of the bones.

These bones have been reduced to this tiny little stump here.

These are true birds.

But long feathers, attached to the tail one of this specimens

can reveal something intruiging about these early birds.

To find out what they were for, we can look for a bird here in Borneo

that has very similar tail feathers.

This is the racket-tailed Drongo

and it's tail feathers there are astonishingly resembleance

to those of a distant ancestors Confuciusornis.

They don't seem to help it's flight in any way.

So the drongo must be using them for something else.

Display.

And so, while birds continue to improve their flight

they also continued to use the feathers in courtship

as their dinosaur ancestors had probably done.

Birds use not just shape of their feathers for display

but also their colour and this is really lovely examples of that.

Here in Borneo.

These birds are colorful enough, but one is particulary spectacular.

This is the Bornean Peacock-Pheasant.

This is the male. His feathers are emblazing with colorful irridescent patterns.

And that is because they used to attract the attention of a female.

Her feathers are comparatively drab.

First, the male lures the female in to his courtship arena with the promise of food.

The worm.

He becames to shake his magnificent feathers.

He clears the ground of anything that might interfere with his performance.

As the female dives in after the worm he raises all of his feathers in a huge fan.

If she approves of his display she might choose him as a mate,

over other rival males.

Eventually she makes off with the offering a food

it seems she was not as impress as she might have been.

So feathers, so lightweight, and so easily erected

can serve as billboards on which appertize for the mate or warn off rivals.

But to see, how the early birds used their feathers to acheive fully powered flight,

we are returning to Britain.

And here, on the Lochs in Scotland we can watch some of the most majestic flyers around today.

Whooper Swans.

These particular birds were in contact with human beings

from the very first moment of their hatched, so they allow me to get really close to them.

The small feathers on their bodies are still essential for keeping their owners warm.

But this one is a wing feather.

It extremely strong, but very light,

and the filaments on either side of the quill and the barbs,

zip together to form a continues surface which will strong enough to hold the air.

But if the air is to support a wing bird as it flies,

it has to move over the wing very fast.

And in order for that to happen, these Swans will move at speed

across the surface of the water like an aircraft taxiing before take-off.

When you close up to a flying bird like this,

you can see how a wonderful piece of complex engineering their wings are,

able to change their shape and their beat

to respond to every little change in the currents of the air around them,

and so propelled them forward and lift them upwards.

So, how the bird wings actually work?

If we slow them down we can watch in detail the mini subtle changes

they make as they move up and down.

The feathers overlap to form a smooth contoured surface

that extends far beyond the bones within.

With a curved leading edge of the front, and a sharp trailing edge of the back

they have a classic aerodynamic shape that produced lift.

They are aerofoils.

With this downward beat the air pressure above is reduced,

so that the bird is sucked upwards.

Wings like these consisting of jointed bones covered with closely fitting feathers

can make very subtle delicate movements.

The feathers slide over one another, so that when the wing changed its shape

there is no loss of smoothness on the contour.

When the Swan slightly retract its wings in between beats,

the sliding feathers ensure that the aerofoils still produces lift.

As well as lightweight beaks and shortened tails,

some of the bones of it's body became hollow.

The result is an extremely efficient light weight flyer.

We are traveling around 30 miles an hour now,

and yet these birds could easily accelerate and leave us behind if they wanted to.

So feathers, since they're first appeared on the bodies of Dinosaurs,

have acquired several different functions.

Initially they served to keep their owners warm.

Then, some grew large and acquired color and were probably use in courtship displays.

And only then, after millions of years,

where they used to help their owners get into the air.

So around 150 million years ago birds joined Pterosaurs and insects in the skies.

Then, around 66 million years ago, came the global catastrophe

that triggered the disappearance of a vast proportions of the animal life of this Planet.

An asteroid hitting the Earth was the most likely cause of this mass extinction.

In the devastation that followed, the dominants creatures of that age,

the Dinosaurs, disappeared.

The Pterosaurs were completely wipeout.

And only a few of the Birds survived.

The skies for a short period must have been relatively empty.

But then, a new kind of flying animal appeared.

Now is a chance for a group of furry warm blooded little creatures,

that has been scampering around the feet of the Dinosaurs for several millions years.

They were the mammals.

The first of them to take to the air were doubtous gliders.

And one mysterious creature still alive today,

can give us an idea of what there were like.

It lives in the rainforests of Borneo, and it called the Cobego.

It has an enormous blanket of furry skin that stretched

from the sides of its head right down to the very tip of its tail.

But to see how he travel through the air, we must wait until nightfall.

As soon as it lands, it regain the height it inevitably lost by clambering up the trunk.

It by far the most skillful of the forest gliders,

and can travel over a 100 meters in one leap.

It's undoubtedly a very ancient animal, and some believe that it may well

have survived virtually unchanged from that time long ago

when mammals first took to the skies as gliders.

But soon, the mammals deed better than that.

This is a fossil that dates from about 52.5 million years ago.

Here its head, a very well develop teeth, backbone and ribs,

a long tail, hind legs, and most importantly of all,

from our point of view, hands with enormously elongated fingers.

And there was skin between those fingers.

These were wings and they could flap.

This is the earliest fossil yet discovered of a bat.

We have new evidence to show exactly how a bat fingers

first began to lengthen to support their wings.

But we can understand how those early bats flew, by looking on their modern descendants.

These are some of the largest.

They so big, that they often called Flying Foxes.

And they have a wingspan of over a meter.

When you slow a bat flight down like this, you can see that its four fingers

are spread wide under down stroke, keeping the membrane wide and taut,

and then clump together on the up stroke, with just a thumb off the top three.

This folding of the wings reduces the bat air resistance between each beat.

To maximise the size of its wing, the back edge of the wing membrane

is attached to the ankles.

Bats roost by hanging upside down.

And this is how they tend to spend their days.

Is thought that the first mammals were nocturnal,

that doubtless was the best thing to be out of the way of the Dinosaurs

that were rampaging around during the day.

So, the bats continue the nocturnal habit of their ancestors,

and they are also inherited the acute sensors needed to move around at night.

Eyes specially adapted to operating well in low light.

And an acute sense of smell that enable them to find food in the dark.

In any case, Birds already dominate in the daytime skies.

With their wings of skin and nocturnal senses the Bats became a hugh global success.

Today there are over 1,100 species of them, that's over a fifth of all mammals.

So, by 50 million years ago, three groups of large backbone animals

had joined the Insects in the air.

The pioneers were reptiles, Pterosaurs,

with membrane of skin stretch from elongated fingers.

Then, came a group of Dinosaurs that acquired feathers and became Birds.

But when the Pterosaurs and Dinosaurs were swept away in a global extinction event,

the stage was set for the Birds and the newly emerge Bats

between them to take command on the skies.

Each of these two groups had evolved its on techniques for getting into the air,

and each was destined to bring theirs skills to astonishing extremes.

Next time, we see how Birds adapted and diversified

to become the remarkable creatures we see in our skies today.

Lethal hunters...

formation flyers... an aerial acrobats.

We explore how the Bats develop a new super sense

that enable them to hunt in the pitch-blackness of the night.

And we visit one spectacular place were the battle for the skies,

between Insects, Bats and Birds still continues.

Written and Presented by David Attenborough

I'm several hundreds feet up in the air,

up here, I might encounter perhaps a flying insect, although I haven't seen one yet,

or maybe even a baby spider clinging to a gossamer of thready silk,

which is their way of getting around. But by in large, this is the kingdom of the birds.

The first birds flew about 150 million years ago.

They spread around the globe, and evolved into a multitude of different kinds.

Aerial acrobats...

stealthy hunters...

and some of the fastest creatures on the planet.

Their extraordinary skills enable them to surpass Earth original flyers, the insects.

But there is a vast kingdom that the birds do not control, the night skies.

These are ruled by very different creatures, flying mammals.

Bats.

And in one spectacular place these two populations,

of the night and the day, collide.

~ Conquest Of The Skies ~

TRIUMPH

This is Segovia in central Spain.

Some of the inhabitants of this gorge allow us to see very clearly

how birds as a group have become so versatile in the air.

Through the ability to change the shape and the size

of their basic flying mechanism, their wing.

And there is wonderful example of that just over here.

You may think that birds are much the same when it comes to flight,

but in fact different species need to fly in their own particularly way.

This vulture is an airborne scavenger.

It feeds on the bodies of dead animals.

So, it need to spot any fresh carcass very quickly, and get to it before others claim it.

Like most birds, it has superb eyesight.

So, it climb high in the sky, constantly scanning the ground below,

for hours at a time if need be.

To fly in this highly specialize way, it is evolved a very distinctive kind of wing.

To get up close to some of the many vultures that live in this area,

I visiting a place where they regularly fed by conservationists.

These are Griffon Vultures, one of the largest of all birds species,

each one can weight up to 11 kilos.

Lifting a 11 kilo body high into the sky takes a lot of energy,

but the vultures don't supply that energy directly themselves.

A clue of how they do so comes from observing their behavior at the start of the day.

Those vultures roost and nest on ledges up there.

They not early rises. That's because they rely on the sun to get airborne.

As tha day warms up, patches of bare rock reflect the heat of the sun,

forming columns of rising hot air known as thermals.

And the vultures know exactly how to exploit those thermals,

to be carry high in the sky with a minimum of effort.

They have wings that have been shaped over millions of years

to catch as much of that rising air as possible.

They huge, very broad, with a span of over 2 meters.

The riding thermals may not be as easy as it looks.

A thermal is quite a narrow column of rising air,

and to stay within it, a vulture has to make quite sharp turns.

And that could lead to disaster.

In a tight spiral, a vulture inside wing

travel a shorter distance than its outer wing.

And if we were to measure the speed of this inner wing,

we will find that it moves much more slowly through the air.

This mean it generates less lift.

So little in fact, that the vulture could easily stall and drop from the sky.

It avoid that by having special control over the feathers at the ends of its wings.

They can be splayed so that they separate.

As a result, each feather acts as a small extra wing,

and together they increase overall lift.

This enable the vulture to turn in a tight circle,

and so hold its place in a thermal and soar upwards.

Using this technique, a vulture can climbe to a height of a kilometer

above the ground with scarcely of flap of its wings.

And then, if it spot food down below,

it can switch its flight technique and descend at speed.

Once on the ground it has to compete with other vultures for the share of the feast.

Now, those broad wings are useful to help muscle out it's rivals.

And that can put those all important wings at risk.

Bird bones being hollow and lightweight are also usually very fragile.

And if a bird breaks it's wings that usually a death sentence,

because most small birds have to feed every day or so.

But this is the wingbone of the vulture

and vultures are so big and can fill their stomach so much food

that they can go without a meal for two or even three weeks.

And as a concequence when these aggressive quarrelsome vultures have a row

and perhaps injure one another, a broken wing can heal itself,

and this is the wingbone of the vulture, as you can see, it has been broken and it has healed.

It's owner may well have lived to soar again.

This soaring tehnique can exploit not just a thermals

but also winds deflected upwards by ridges and hills.

The same wing shape is used by other large birds to help them soar.

Eagles.

Pelicans.

And the bird that makes immense journey here to Spain every summer.

Two young storks.

Their parents come here every year to this small town in northern Spain

in order to mate and nest and rear their young all the way from Africa.

Some from as far south as the Cape. And they make that immense journey

by finding a thermal of a column of rising air.

Circling in it, allowing it to carry them high in the sky,

and then gliding off on the next stage of the journey

to find another thermal to take them back up again.

It's an extraordinary energy efficient way of travelling.

So broad wings and splade wingtips enabled larger birds to stay airborne.

But other birds faced very different challenges and so evolved different specialities.

To watch a bird that has evolved in to one of the worlds most skilful hunters,

I have comed to Italy and the city of Rome.

There is a bird that fly over these roofs,

that find its prey not on the ground, but in the air.

And it owe its success to its speed.

In fact, it said to be the fastest moving animal on Earth. The Peregrine.

Peregrines hunt other birds.

Many different kinds of birds now live in cities,

attracted by the food and shelter that is so easily found here.

And a tall building like this is an ideal lookout for a hunter.

Flying prey can move in any direction it chooses,

so a hunter has to be both, fast and agile if it to get a meal.

A peregrine wings have a very special shape.

They pointed and swept back.

If wings have a blunt end, air will swirl over that end,

forming trails of turbulents.

These act like brakes slowing a bird down.

But pointed wings had shrink that edge, and so reduce the turbulents.

Pulling the wings back towards the body, makes the bird even more streamlined.

And speed is crucial to a peregrine success.

It also has acute vision that enable it to spot prey over a mile away.

And for the peregrine that hunt in Rome, these birds are prime targets.

Starlings.

They too are fast flyers,

and their smaller size make them even more maneuverable.

So, to catch a starling a peregrine must be even faster,

and in order to gain speed and surprise, it attacks from above.

First, it climbs.

When it sees a group of its potential prey, it turns...

dives... and accelerate by beating its wings.

The starlings are still unaware of the danger hurtling toward them.

Finally the peregrine draws its wings back. This is called the stoop,

a superb streamline shape that slices through the air.

Now, it can reach speed of over 200 miles an hour.

As it neared its target, it open its wings

to slow its descent and makes its final launch.

Starlings in fact, are an abundance source of food for the peregrines.

They come into the city in the winter, attracted no doubt by the warmth in order to roost.

Every evening at dusk, the starlings start to arrive,

and they have a remarkable way of defending themselves against peregrines.

One that relies on their ability to fly together in tight formations as a flock.

And here they come, vast numbers of them, tens of thousands, hundreds of thousands.

It's like a great black hailstorm, a blizzard of birds.

And now, some start to fly closely together and perform far more complex maneuvers.

Look how these great flocks come together, form a cloud, veer away and split,

It's a quite extraordinary piece of aerial navigation.

We still unsure exactly why they perform these elaborate dances,

but they often triggered by the arrival of a predator.

And today is no exception, because over there,

on one of those buildings I have seeing a peregrine.

Coming in a great numbers like this, is in itself a defense,

because if you surrounded by tens of thousands of others,

well, it's a good chance that the peregrine won't get you.

But the aerial ballet is part of a more complex defensive strategy.

When a peregrine does attack with its wings drawing back in its stoop,

the starlings flying in their tight formation coordinate their escape.

Instead of scattering in different directions when a struggler might be picked off,

they stick together, even when they make the sharpest of turns.

Recent studies analyzing the flight birds of these Roman flocks,

have now revealed how they manage to do this.

Just how they achieve this was not understood until very recently.

But now a team of physicists from Sapientia University in Rome

is beginning to find the answers.

We see these huge flocks of birds dancing in front of us

and every time that you look at them you wonder,

how it is possible that so many birds would be as only one entity.

They precisen series of cameras on a rooftop overlooking a favourite starling roostsite

just outside Rome's main railway station.

The cameras record the flocks complex manouvers in three-dimensions.

Advanced computer software then locks on to the flightpods of thousands of individuals,

with extraordinary precision.

Their painstaking work has produced a remarkable insight

into how starlings coordinate their behaviour.

The main result that we found is that each bird interacts with the seven birds around it.

Regardless of the distance between these birds it is the key to have a stable flock.

And individual starling is affectively linked to seven around it by an invisible web,

even if they drift far apart.

This is the hidden glue binding the flock together.

But it may also act as a communication channel.

A bird that turns to evade a predator triggers a ripple effect

that passes rapidly through the overlapping networks,

causing the whole flock to turn as one.

Special thing is that the information can be passed through the flock in milliseconds

and this allows them to escape very quickly from predators.

Most of the time the starlings flock defence keeps them alive.

But now and again the share spreed and surprise of peregrins diving attack prooves too strong.

Out of the millions of starlings in the skies

only a few will fall pray to the peregrins tonight.

As the light finally fades, the flock suddenly descends into the trees

that will be their roost for the night.

The peregrines sharp eyesight doesn't operate nearly so well in the dark.

So now, the starlings are safe... until tomorrow that is.

6,000 miles away in South America,

there are other birds with a very different skill.

And they also find their food on the wind.

In the Cloud Forest of Ecuador there is a plentiful supply of a type of food

produce by plants to attract flying animals.

Nectar.

Around 130 million years ago, plants recruited insects to transport pollen

from one flower to another by bribing them with a sugar rich drink.

Birds when they first evolved were unable to collect it,

because there where seldom something solid nearby, on which they could perch.

Then, around 30 million years ago,

a kind of bird appeared that had no need of such a perch.

Hummingbirds.

They could hover.

They do so by beating their wings extremely swiftly,

so fast in fact, that they make a humming noise.

The largest hummingbird beat its wings around 14 times a second,

but some tiny species are able to do so 80 times a second.

To fly in this extraordinary way, hummingbirds have changed

the structure of their wings and the way they beat them.

Here in Ecuador, scientist Doug Altshuler

is working to analyse exactly how they do so.

Hummingbirds are remarkable animals, they have extreme adaptations in physiology and anatomy,

and they also have a very unique behavior, they can hover,

and the approach that we have taken is to study how those

physiological and anatomical adaptations determine their hovering ability.

Using High-Speed cameras, he record the mechanics of their flight in minute detail.

He can slowdown the action by around 40 times,

and so observe exactly what's taking place.

Most birds flap their wings up and down,

but hummingbirds flap theirs more like insects.

They twist their wings around between strokes,

and so can generate lift when flapping both forwards and backwards.

Doing this at high speed put a huge straying on their wings.

So, to withstand it, the wings have a special structure.

The hummingbird wing is very stiff, and undergo a few changes in shape

as it rapidly beats back and forth.

They owe this stiffness to a modification of the bones.

The arm bones have shrunk, but the bones of the hand

have elongated and support most of the wing surface.

Twisting this wing of the shoulder and at the wrist

produces the hummingbird distinctive wing beat.

Doug is also investigating one of the great mysteries of hummingbird flight.

Their ability to move sideways in mid-hover.

Hummingbirds are able to track flowers that are moving back and forth in the wind,

and this was something I always wanted to know more about.

To replicate the swaying motion of a flower,

Doug places a reservoir of nectar on a mechanical slider.

Befor long, he has a volunteer.

Amazingly, it manages to track sideways to keep-up with the slider, and still feed.

The bird is exploiting an unexpected feature of its wing beat,

not the flapping itself, but the twists at the end of each stroke.

During hovering flight, as the wings come forward,

they rotate symmetrically, so the froces remain in balance,

but if they instead rotate differently, so that one wing rotate before the other,

then the forces are no longer in balance,

and this asymmetry can be sufficient to push them to one side of the other.

So, a combination of modified wing bones, and precise control of wing motion,

gives hummingbirds the aerial agility they need to collect nectar.

And they need plenty of it, hovering burns a huge amount of fuel.

All hummingbirds have to constantly top at their tacks with high energy nectar.

And when supply are low, competition can be fierce.

Now, their flying skills are put to a very different use.

To fight off rivals.

So, different birds adapted their wings to fly in highly specialise ways.

Some began to hunt the Earth first flyers, the insects,

and in that battle, there is now no real contest.

But because most birds rely for so much of their success

on their exceptional eyesight, there is one major habitat that is largely close to them,

not a place, but a time,

the night.

In the British countryside however, there is a bird that can fly in the dark.

The Barn Owl and one of its favorite meals is a Field Mouse.

But first, it has to find it in the dark.

A mouse is extremely alert to the approach of a predator.

But the Barn owl has wings specially adapted for stealth,

and senses that can penetrate darkness.

Its eyes are very sensitive in low light, but even if the mouse is out of sight,

it's still not safe, the owl's hearing is also very acute.

Those two disks on its face channel sound into its two ears,

which are on a slightly different level on the head,

and that difference enables the bird to pinpoint the source of the sound,

whether it's in the air, or down on the ground.

But in order to hear that sound, its wing beats have to be very very quiet,

and the way to achieve that, we can see when it go hunting.

The key reason for it silent flight lies in the nature of its wing feathers.

Along the back edge, their fringe is frayed and tatty.

Most birds wings have a hard edge,

and this can cause quite a loud noise.

The source is turbulents produce when air flowing over the wing rub against its surface.

When this swirling air meet a hard back edge,

the sudden drop-off hugely amplifies the noise.

But the Barn Owl tatty feathers avoid that, by creating a softer edge,

they cushion the turbulent air and so reduce noise.

So, silent flight allow the owl to hear its prey,

and conceal its approach.

But to position itself for the kill it need to fly extremely slowly,

and to achieve that it has particularly broad wings.

This slow silent approach leaves a field mouse little chance of escape.

On nights, when there is thick clouds or no moon,

even an owl sensitive eyes struggle.

But there are creatures that have such highly specialise senses

that they able to navigate in total darkness.

Among insects, there are some moths who their elaborate antenna

are able to pick-up the scent of food or a mate.

And there are those nocturnal animals,

the last group of flying creatures to appear on Earth, the bats.

To see how they battle with the insects for dominate of the night skies,

we heading into the rainforests of Borneo.

Many bats find their food not by sight or smell,

but by using a very different and highly advance guiding system.

One way to find them, is to search for their ideal home,

a place like that deep black cave beneath me.

If you fly at night, there is no better place to spend the day

than in a cave like that.

This is Gomantong.

The cave is a vast network of underground tunnels and cathedrals size cabins.

It was carve out by streams of water over millions of years.

And now, it's home to a remarkable community of cave dwelling specialists.

To find the creatures I'm looking for, I'm been winch high up towards the ceiling,

where the towering walls make ideal roost sites for flying animals.

These little birds fly pass me are Swiftlets

that have made their nests on the walls of the cave.

They are active during the day, and they leave the cave to hunt insects.

The bats, that are I'm interesting in, are further behind me in the semidarkness,

and there are sleep now, during the day.

The bats are scarcely the size of mice,

their wings are constructed with very long fingers,

and they hang by their feet from the rock.

Although there are few of the bats there,

deeper in this cave they exist in huge numbers.

To find their roosts we heading still deeper into Gomantong cave.

High on the rocky cave ceiling above me, hidden in the darkness,

there are vast numbers of bats.

You can get some idea of how many there must be,

because of this huge dune behind me, that form of their droppings,

and if you see little moving glimpse on the surface,

that comes from an army of cockroachs which are chewing their way

through the bats droppings to extract the last particles of nutriment.

Some pepole think there are a million bats up here in this cave.

It's impossible to see them in the gloom,

but special night vision cameras can reveal them,

densely pack crowds hanging form the ceiling.

Their tiny eyes are adapted to low light, but they cannot penetrate the blackness.

Millions of years ago however, these bats evolve

an extraordinary guiding system known as echolocation or sonar.

A bat produces extremely hyper sounds in its throat, and then project them forward.

We have slow the sounds down, but can still only hear them

by converting them to lower frequencies.

They bounce of the walls as echoes and are detected by the bat huge ears.

These are in constant movement and enable the bat

to map its surroundings with remarkable precision.

But these bats not only need to find their way in the dark,

they also need to find their food.

Night flying insects.

And among them are moths.

Locking-on to these moving targets is a supreme test

for the bats echolocation system.

As one homes in, its sonar beam switches into attack mode,

increasing the rate of its pulses.

This enables it to precisely pinpoint the location of its prey.

But in the battle of the nightskies the bats don't have it all in their own way.

A team of scientists in Borneo is studing the way bats interact with their pray.

First, they catch the bat into the trap

that uses thin wires to divert to main in the pouch below.

There it is. - Nice.

Ye this is gorgeous.

Bats and moths have could evolved for almost 60 million years

and so what we doing here with this giant tent and all these cameras

is to trying figure out what's happening in this ancient battle.

Trying to understand how moths survive a bat attack.

Everything set up here? - Yes, everything ready to go. - Awesome.

This tent acts as an controlled flight arena,

in which every movement and sound can be recorded in minute detail.

Filming these interactions with multiple cameras in 3-D and ultrasonic microphones,

we can see how these interaction unfold, and hear how they unfold.

These studies have revealed that moths do not always fall prey to the bat attacks.

We know that many moths have bat detecting ears

they can hear the bats coming, they hear their echolocation cries

and dive out of the sky stop flying.

You got it? - There you go.

But the teams works identified a moth, with very different defence strategy.

Playing recordings of a bat sounds to this moth reveals a remarkable ability.

Here in Borneo, we recently discover that Hawk Moths

respond to these echolocation cries with their own sounds.

Hawk Moth is now direction.

Hawk Moths do with the tip of their abdomen with modified genitals,

they rub the genitals against the inside of the abdomen,

and reply to this bat attack.

The moth is tether to keep it in range of the cameras and microphones,

then a bat is released.

As the bat approaches the moth, its sonar pulse switches to attack mode,

but now the Hawk Moth responds,

sending its own rasping sound back with astonishing effect.

At the last moment, the bat appears to lose track of the moth, and fails to catch it.

We have shown that these moth sounds actually jam the bat sonar,

they interfere with the returning echoes from the insect,

and causes the bat to miss the moth.

The team has discovered that insects are fighting back

in the ongoing battle for the night skies.

But there are, of course, plenty of other flying insects with no such defenses.

and they live in vast numbers in the forest outside Gomantong cave.

So, every evening as dusk arrive,

the bats leave the safety of their secluded home to hunt.

And now, the bats are been in use their echolocation skill

to fly out from their roosts in the depths of the cave,

coming close to the ceiling and then wheezing out through this little entrance here.

They don't collide with the roof, they don't collide with one another,

or even with me, all to that echolocation. There they go!

But this is just a trickle, the main exodus

is taking place up a chimney that's deeper in the cave.

To watch close-up the way the bats achieve their million strong mass departure,

I'm being hold-up 200 feet into the tunnel which serves as one of the cave main exits.

At the top, there is a gaping hole.

And now, the bats are preparing to leave.

They have assemble in a relatively small chamber close to the exit,

and are flying round and round in a great swirling crowd,

waiting dor day light to fade.

And now, off they go.

This refire of dusk is the moment when the two communities,

the day flyers and the night flyers may encounter one another in the air.

Outside danger awaits,

hunters belonging to that other great group of animals

with which their shares the skies... birds.

Hawks, Eagles and Kites.

They are why the bats were reluctant to leave,

and why they now do so in one continuous torrent, there is safety in numbers.

But some will pay the price.

The vast majority, of course, make it out over the forest canopy,

and there they can use that skill of echolocation to find food.

The way that different animals have colonise the skies

is surely one of the most remarkable stories in the natural world.

First to do so, over 320 million years ago, were the insects.

They had no competition for about 100 million years.

But then, much larger flying animals took in the air. Reptiles. The pterosaurs.

Around 70 million years later still, one branch of the dinosaurs acquired feathers,

and that enable their owners to get airborne.

The birds had arrived.

And last in, about 60 million years ago,

the night skies where invaded by mammals, the bats.

And here, in Gomantong cave, the three surviving groups of flyers,

insects, birds and bats, are still lock together in an ongoing evolutionary struggle.

So, the battle for the supremacy of the skies,

that started over 300 million years ago,

still continues every day around the world.

Written and Presented by David Attenborough

Texting: Bobiko, danel32. Timing: danel32.