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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.