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I'm several hundreds
feet up in the air.

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Up here, I might encounter
perhaps a flying insect,

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although I haven't seen one yet,

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

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which is their way
of getting around.

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But by and large, this is the kingdom of the birds.

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The first birds flew about 150
million years ago.

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They spread around the globe

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and evolved into a
multitude of different kinds.

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Aerial acrobats...

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stealthy hunters...

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and some of the fastest
creatures on the planet.

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Their extraordinary skills enable them
to surpass Earth's original flyers,

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the insects.

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

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the night skies.

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These are ruled by
very different creatures,

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flying mammals.

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The Bats.

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And in one spectacular place
these two populations,

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of the night
and the day,

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collide.

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This is Segovia in central Spain.

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

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

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Through the ability to change
the shape and the size

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of their basic flying mechanism,
their wing.

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And there is wonderful example
of that just over here.

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

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

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This vulture is an airborne scavenger.

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It feeds on the bodies of dead animals.

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So it needs to spot any fresh
carcass very quickly,

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and get to it before others claim it.

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Like most birds,
it has superb eyesight.

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So it climbs high in the sky,

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constantly scanning
the ground below,

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for hours at a time if need be.

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To fly in this highly specializeв way,

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it has evolved a very distinctive kind of wing.

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

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I am visiting a place where they are regularly fed by conservationists.

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

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each one can weight
up to 11 kilos.

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

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

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A clue of how they do so

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comes from observing their
behavior at the start of the day.

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Those vultures roost and nest
on ledges up there.

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They're not early rises.

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That's because they rely
on the sun to get airborne.

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

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forming columns of rising
hot air known as thermals.

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And the vultures know exactly
how to exploit those thermals,

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

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They have wings that have been
shaped over millions of years

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to catch as mush of that
rising air as possible.

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

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

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A thermal is quite a narrow
column of rising air,

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

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And that could lead to disaster.

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In a tight spiral,
a vulture inside wing

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travel a shorter distance
than its outer wing.

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

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

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This mean it generates less lift.

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So little in fact, that
the vulture could easily

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stall and drop from the sky.

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It avoid that by
having special control

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over the feathers at
the ends of its wings.

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They can be splayed
so that they separate.

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

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and together they
increase overall lift.

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This enable the vulture
to turn in a tight circle,

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

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

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above the ground with
scarcely of flap of its wings.

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And then, if it spot
food down below,

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it can switch its flight technique
and descend at speed.

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A dead animal, once found,
makes an easy meal,

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except for the fact that there
are rather a lot of dinners.

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But other meat eating birds
have even greater problems.

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They pursue living prey,
and one such hunter

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has become one of the fastest
of all living creatures.

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To watch one of the fastest
of all flying animals,

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I have comed to Italy
and the city of Rome.

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There is a bird that
fly over these roofs,

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

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And it owe its success
to its speed.

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

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The Peregrine.

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Peregrines hunt other birds.

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Many different kinds of birds
now live in cities,

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

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

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Flying prey can move in
any direction it chooses,

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

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A peregrine wings have
a very special shape.

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They pointed and swept back.

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

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forming trails of turbulents.

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These act like brakes
slowing a bird down.

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

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

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And speed is crucial
to a peregrine success.

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

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

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Starlings.

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They too are fast flyers,

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and their smaller size make them
even more maneuverable.

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

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

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First, it climbs.

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

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dives...

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and accelerate by
beating its wings.

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

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Finally the peregrine
draws its wings back.

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This is called the stoop,

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a superb streamline shape
that slices through the air.

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

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As it neared its target,
it open its wings

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to slow its descent and
makes its final launch.

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

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They come into the
city in the winter,

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attracted no doubt by the
warmth in order to roost.

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Every evening at dusk,
the starlings start to arrive,

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

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One that relies on their
ability to fly together

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in tight formations as a flock.

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And here they come,
vast numbers of them,

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tens of thousands,
hundreds of thousands.

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

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And now, some start
to fly closely together

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and perform far more
complex maneuvers.

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Look how these great
flocks come together,

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form a cloud,
veer away and split,

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It's a quite extraordinary
piece of aerial navigation.

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We still unsure exactly why they
perform these elaborate dances,

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but they often triggered by
the arrival of a predator.

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And today is no exception,
because over there,

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on one of those buildings
I have seeing a peregrine.

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

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because if you surrounded by
tens of thousands of others,

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

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

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

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the starlings flying in their tight
formation coordinate their escape.

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

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

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Recent studies analyzing the flight
birds of these Roman flocks,

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have now revealed how
they manage to do this.

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Each individual starling is
constantly tracking the movements

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of up to 7 of its
close neighbors,

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even if they drift far apart.

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This is the hidden glue
binding the flock together.

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And it can also help the birds to
communicate among themselves.

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A bird that turns to evade
a predator triggers a ripple

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that passes through the overlapping
networks in milliseconds.

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And that causes the all
flock to turn as one.

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

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that will be their
roost for the night.

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

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So now, the starlings are safe...

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until tomorrow that is.

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6,000 miles away in
South America,

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there are other birds with
a very different skill.

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And they also find their
food on the wind.

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

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produce by plants
to attract flying animals.

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Nectar.

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

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

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Birds when they first evolved
were unable to collect it,

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

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Then, around 30 million years ago,

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

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Hummingbirds.

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They could hover.

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They do so by beating their
wings extremely swiftly,

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

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

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

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To fly in this extraordinary way,
hummingbirds have changed

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

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Here in Ecuador,
scientist Doug Altshuler

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is working to analyse
exactly how they do so.

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Hummingbirds are
remarkable animals,

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they have extreme adaptations
in physiology and anatomy,

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00:18:38,158 --> 00:18:41,913
and they also have a very
unique behavior, they can hover,

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

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physiological and anatomical adaptations
determine their hovering ability.

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00:18:52,994 --> 00:18:59,336
Using High-Speed cameras, he record the
mechanics of their flight in minute detail.

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He can slowdown the
action by around 40 times,

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and so observe exactly
what's taking place.

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00:19:14,963 --> 00:19:17,846
Most birds flap their
wings up and down,

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00:19:17,885 --> 00:19:22,151
but hummingbirds flap theirs
more like insects.

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00:19:23,366 --> 00:19:26,216
They twist their wings
around between strokes,

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00:19:26,242 --> 00:19:31,493
and so can generate lift when flapping
both forwards and backwards.

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00:19:36,944 --> 00:19:41,048
Doing this at high speed put
a huge straying on their wings.

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00:19:44,797 --> 00:19:48,908
So, to withstand it, the wings
have a special structure.

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00:19:50,529 --> 00:19:54,072
The hummingbird wing is very stiff,
and undergo a few changes in shape

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as it rapidly beats
back and forth.

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00:20:05,813 --> 00:20:09,924
They owe this stiffness to a
modification of the bones.

206
00:20:12,186 --> 00:20:15,936
The arm bones have shrunk,
but the bones of the hand

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00:20:15,941 --> 00:20:19,841
have elongated and support
most of the wing surface.

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00:20:22,545 --> 00:20:25,166
Twisting this wing of the
shoulder and at the wrist

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00:20:25,192 --> 00:20:29,166
produces the hummingbird
distinctive wing beat.

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00:20:35,591 --> 00:20:40,696
Doug is also investigating one of the
great mysteries of hummingbird flight.

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00:20:42,072 --> 00:20:46,764
Their ability to move
sideways in mid-hover.

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00:20:47,169 --> 00:20:51,072
Hummingbirds are able to track flowers
that are moving back and forth in the wind,

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00:20:51,115 --> 00:20:54,182
and this was something I
always wanted to know more about.

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00:20:55,680 --> 00:20:58,343
To replicate the swaying
motion of a flower,

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00:20:58,386 --> 00:21:02,823
Doug places a reservoir of
nectar on a mechanical slider.

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00:21:07,011 --> 00:21:10,075
Befor long,
he has a volunteer.

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00:21:17,720 --> 00:21:20,787
Amazingly, it manages
to track sideways

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to keep-up with the slider,
and still feed.

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00:21:25,666 --> 00:21:29,549
The bird is exploiting an
unexpected feature of its wing beat,

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00:21:29,575 --> 00:21:34,774
not the flapping itself, but the
twists at the end of each stroke.

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00:21:35,113 --> 00:21:37,667
During hovering flight,
as the wings come forward,

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00:21:37,705 --> 00:21:40,784
they rotate symmetrically,
so the froces remain in balance,

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00:21:40,810 --> 00:21:46,181
but if they instead rotate differently,
so that one wing rotate before the other,

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then the forces are
no longer in balance,

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00:21:48,663 --> 00:21:52,944
and this asymmetry can be sufficient
to push them to one side of the other.

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00:21:56,858 --> 00:22:01,517
So, a combination of modified wing bones,
and precise control of wing motion,

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00:22:01,559 --> 00:22:06,600
gives hummingbirds the aerial
agility they need to collect nectar.

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00:22:07,197 --> 00:22:12,659
And they need plenty of it,
hovering burns a huge amount of fuel.

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00:22:14,427 --> 00:22:17,644
All hummingbirds have to
constantly top at their tacks

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with high energy nectar.

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00:22:20,716 --> 00:22:24,981
And when supply are low,
competition can be fierce.

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00:22:29,510 --> 00:22:33,206
Now, their flying skills are
put to a very different use.

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To fight off rivals.

234
00:23:09,921 --> 00:23:15,370
So, different birds adapted their
wings to fly in highly specialise ways.

235
00:23:16,418 --> 00:23:20,613
Some began to hunt the Earth
first flyers, the insects,

236
00:23:21,980 --> 00:23:26,749
and in that battle, there
is now no real contest.

237
00:23:37,461 --> 00:23:40,386
But because most birds rely
for so much of their success

238
00:23:40,414 --> 00:23:43,073
on their exceptional eyesight,

239
00:23:43,108 --> 00:23:46,683
there is one major habitat
that is largely close to them,

240
00:23:46,715 --> 00:23:49,842
not a place,
but a time,

241
00:23:51,182 --> 00:23:54,137
the night.

242
00:23:58,432 --> 00:24:00,871
In the British countryside however,

243
00:24:00,906 --> 00:24:04,727
there is a bird that
can fly in the dark.

244
00:24:09,052 --> 00:24:12,143
And it's a very skillful hunter.

245
00:24:23,108 --> 00:24:28,022
The Barn Owl is one of only a very
few birds that can hunt at night,

246
00:24:29,065 --> 00:24:33,833
and one of its favorite
meals is a Field Mouse.

247
00:24:34,903 --> 00:24:38,063
But first, it has to
find it in the dark.

248
00:24:39,693 --> 00:24:44,273
A mouse is extremely alert
to the approach of a predator.

249
00:24:49,642 --> 00:24:53,805
But the Barn owl has wings
specially adapted for stealth,

250
00:24:55,819 --> 00:24:59,568
and senses that can
penetrate darkness.

251
00:25:16,101 --> 00:25:21,245
Its eyes are very sensitive in low light,
but even if the mouse is out of sight,

252
00:25:21,298 --> 00:25:26,490
it's still not safe, the owl's
hearing is also very acute.

253
00:25:26,522 --> 00:25:32,127
Those two disks on its face
channel sound into its two ears,

254
00:25:32,164 --> 00:25:35,907
which are on a slightly
different level on the head,

255
00:25:36,028 --> 00:25:40,354
and that different enable the bird
to pinpoint the source of the sound,

256
00:25:40,390 --> 00:25:43,917
whether it's in the air,
or down on the ground.

257
00:25:44,198 --> 00:25:50,208
But in order to hear that sound, its
wing beats have to be very very quiet,

258
00:25:50,655 --> 00:25:55,885
and the way to achieve that,
we can see when it go hunting.

259
00:26:16,051 --> 00:26:21,359
The key reason for it silent flight
lies in the nature of its wing feathers.

260
00:26:22,641 --> 00:26:27,203
Along the back edge, their
fringe is frayed and tatty.

261
00:26:28,660 --> 00:26:31,037
Most birds wings
have a hard edge,

262
00:26:31,110 --> 00:26:33,923
and this can cause
quite a loud noise.

263
00:26:34,270 --> 00:26:39,981
The source is turbulents produce when air
flowing over the wing rub against its surface.

264
00:26:40,295 --> 00:26:43,490
When this swirling air
meet a hard back edge,

265
00:26:43,554 --> 00:26:47,975
the sudden drop-off hugely
emphasize the noise.

266
00:26:49,359 --> 00:26:54,855
But the Barn Owl tatty feathers
avoid that, by creating a softer edge,

267
00:26:54,870 --> 00:26:59,384
they cushion the turbulent
air and so reduce noise.

268
00:27:07,962 --> 00:27:12,341
So, silent flight allow the
owl to hear its prey,

269
00:27:12,680 --> 00:27:16,098
and conceal its approach.

270
00:27:19,271 --> 00:27:24,443
But to position itself for the kill
it need to fly extremely slowly,

271
00:27:24,507 --> 00:27:29,447
and to achieve that it has
particularly broad wings.

272
00:27:37,462 --> 00:27:42,894
This slow silent approach leaves a
field mouse little chance of escape.

273
00:28:05,587 --> 00:28:08,450
On nights, when there is
thick clouds or no moon,

274
00:28:08,509 --> 00:28:12,363
even an owl sensitive
eyes struggle.

275
00:28:18,304 --> 00:28:21,871
But there are creatures that
have such highly specialise senses

276
00:28:21,914 --> 00:28:26,349
that they able to
navigate in total darkness.

277
00:28:28,039 --> 00:28:31,660
Among insects, there are some
moths who their elaborate antenna

278
00:28:31,682 --> 00:28:35,387
are able to pick-up the
scent of food or a mate.

279
00:28:38,424 --> 00:28:41,090
And there are those
nocturnal animals,

280
00:28:41,117 --> 00:28:44,169
the last group of flying
creatures to appear on Earth,

281
00:28:44,204 --> 00:28:47,166
the bats.

282
00:28:47,655 --> 00:28:52,081
To see how they battle with the
insects for dominate of the night skies,

283
00:28:52,113 --> 00:28:56,287
we heading into the
rainforests of Borneo.

284
00:29:11,859 --> 00:29:15,501
Many bats find their
food not by sight or smell,

285
00:29:15,527 --> 00:29:20,341
but by using a very different
and highly advance guiding system.

286
00:29:21,830 --> 00:29:25,880
One way to find them, is to
search for their ideal home,

287
00:29:25,928 --> 00:29:31,687
a place like that deep
black cave beneath me.

288
00:29:32,150 --> 00:29:36,182
If you fly at night, there is no
better place to spend the day

289
00:29:36,240 --> 00:29:39,266
than in a cave like that.

290
00:29:44,680 --> 00:29:47,662
This is Gomantong.

291
00:29:56,008 --> 00:29:59,405
The cave is a vast network
of underground tunnels

292
00:29:59,426 --> 00:30:02,521
and cathedrals size cabins.

293
00:30:11,001 --> 00:30:15,692
It was carve out by streams of
water over millions of years.

294
00:30:20,324 --> 00:30:25,776
And now, it's home to a remarkable
community of cave dwelling specialists.

295
00:30:37,216 --> 00:30:42,351
To find the creatures I'm looking for,
I'm been winch high up towards the ceiling,

296
00:30:42,403 --> 00:30:47,771
where the towering walls make ideal
roost sites for flying animals.

297
00:30:57,396 --> 00:31:00,875
These little birds try
pass me are Swiftlets

298
00:31:00,907 --> 00:31:05,299
that have made their nests
on the walls of the cave.

299
00:31:06,840 --> 00:31:11,680
They are active during the day, and
they leave the cave to hunt insects.

300
00:31:13,703 --> 00:31:18,040
The bats, that are I'm interesting in,
are further behind me in the semidarkness,

301
00:31:18,146 --> 00:31:21,259
and there are sleep now,
during the day.

302
00:31:21,845 --> 00:31:24,877
The bats are scarcely
the size of mice,

303
00:31:24,915 --> 00:31:28,897
their wings are constructed
with very long fingers,

304
00:31:28,929 --> 00:31:32,270
and they hang by their
feet from the rock.

305
00:31:33,752 --> 00:31:36,190
Although there are
few of the bats there,

306
00:31:36,211 --> 00:31:40,092
deeper in this cave they
exist in huge numbers.

307
00:31:44,750 --> 00:31:50,003
To find their roosts we heading
still deeper into Gomantong cave.

308
00:31:52,082 --> 00:31:56,326
A huge black dune fill the back
of one of the main chambers,

309
00:31:56,348 --> 00:32:00,945
it made up entirely of the
droppings of the vast numbers of bats

310
00:32:00,965 --> 00:32:03,948
hanging above in the darkness.

311
00:32:08,592 --> 00:32:12,386
To see them fly,
we must wait for dusk.

312
00:32:21,962 --> 00:32:25,988
The great tropical island of
Borneo contains many huge caves,

313
00:32:26,036 --> 00:32:29,519
and one of the biggest
is Gomantong.

314
00:32:30,970 --> 00:32:35,393
High on the rocky cave ceiling
above me, hidden in the darkness,

315
00:32:35,436 --> 00:32:39,162
there are vast numbers of bats.

316
00:32:39,387 --> 00:32:41,812
You can get some idea
of how many there must be,

317
00:32:41,820 --> 00:32:45,097
because of this huge
dune behind me,

318
00:32:45,105 --> 00:32:48,580
that form of their droppings,

319
00:32:48,801 --> 00:32:52,433
and if you see little moving
glimpse on the surface,

320
00:32:52,465 --> 00:32:57,895
that comes from an army of
cockroachs which are chewing their way

321
00:32:57,924 --> 00:33:02,737
through the bats droppings to extract
the last particles of nutriment.

322
00:33:07,998 --> 00:33:13,251
Some pepole think there are a
million bats up here in this cave.

323
00:33:16,568 --> 00:33:19,657
It's impossible to
see them in the gloom,

324
00:33:21,385 --> 00:33:24,437
but special night vision
cameras can reveal them,

325
00:33:24,464 --> 00:33:28,629
densely pack crowds
hanging form the ceiling.

326
00:33:33,184 --> 00:33:35,685
Their tiny eyes are
adapted to low light,

327
00:33:35,701 --> 00:33:38,768
but they cannot penetrate
the blackness.

328
00:33:40,066 --> 00:33:42,660
Millions of years ago
however, these bats evolve

329
00:33:42,667 --> 00:33:48,212
an extraordinary guiding system
known as echolocation or sonar.

330
00:33:53,106 --> 00:33:56,777
A bat produces extremely
hyper sounds in its throat,

331
00:33:56,804 --> 00:33:59,725
and then project them forward.

332
00:34:01,712 --> 00:34:05,147
We have slow the sounds down,
but can still only hear them

333
00:34:05,174 --> 00:34:08,653
by converting them
to lower frequencies.

334
00:34:09,515 --> 00:34:12,160
They bounce of the
walls as echoes

335
00:34:12,192 --> 00:34:15,766
and are detected
by the bat huge ears.

336
00:34:18,230 --> 00:34:21,041
These are in constant
mevement and enable the bat

337
00:34:21,082 --> 00:34:24,886
to map its surroundings
with remarkable precision.

338
00:34:36,006 --> 00:34:38,930
But these bats not only need
to find their way in the dark,

339
00:34:38,967 --> 00:34:42,582
they also need to find their food.

340
00:34:43,099 --> 00:34:46,079
Night flying insects.

341
00:34:46,525 --> 00:34:49,514
And among them are moths.

342
00:34:49,997 --> 00:34:53,408
Locking-on to these moving
targets is a supreme test

343
00:34:53,450 --> 00:34:56,461
for the bats echolocation system.

344
00:34:58,154 --> 00:35:02,451
As one home in, its sonar
beam switches into attack mode,

345
00:35:02,472 --> 00:35:05,701
increasing the rate of its pulses.

346
00:35:15,387 --> 00:35:20,466
This enable it to precisely
pinpoint the location of its prey.

347
00:35:22,684 --> 00:35:27,120
But the bats don't have it all
in their own way in the darkness.

348
00:35:29,441 --> 00:35:32,345
A team of scientists
in Borneo has discovered

349
00:35:32,372 --> 00:35:36,931
that there is another creature here
that uses sound as a weapon.

350
00:35:39,842 --> 00:35:42,827
Everything set up here? -ye,
everything ready to go. -awesome.

351
00:35:42,945 --> 00:35:46,613
This tent act as an
enclose flight arena,

352
00:35:46,639 --> 00:35:51,967
in which every movement and sound
can be recorded in minute detail.

353
00:35:52,256 --> 00:35:55,065
With these cameras and
ultrasonic microphones,

354
00:35:55,071 --> 00:35:57,412
we can see how these
interaction unfold,

355
00:35:57,458 --> 00:36:00,535
and hear how they unfold.

356
00:36:01,739 --> 00:36:05,700
The team play recordings
of bats sounds to moths.

357
00:36:06,182 --> 00:36:09,637
This reveals a remarkable ability.

358
00:36:09,783 --> 00:36:13,099
Here in Borneo, we recently
discover that Hawk Moths

359
00:36:13,120 --> 00:36:18,106
respond to these echolocation
cries with their own sounds.

360
00:36:19,177 --> 00:36:21,938
Hawk Moth is now direction.

361
00:36:23,631 --> 00:36:28,107
Hawk Moths do with the tip of
their abdomen with modified genitals,

362
00:36:28,133 --> 00:36:31,793
they rub the genitals against
the inside of the abdomen,

363
00:36:31,814 --> 00:36:35,607
and reply to this bat data.

364
00:36:36,079 --> 00:36:39,669
The moth is tether to keep it in
range of the cameras and microphones,

365
00:36:39,701 --> 00:36:43,642
then a bat is released.

366
00:36:53,482 --> 00:36:58,730
As the bat approaches the moth, its
sonar pulse switches to attack mode,

367
00:37:00,208 --> 00:37:02,501
but now the Hawk Moth responds,

368
00:37:02,512 --> 00:37:08,154
sending its own rasping sound
back with astonishing effect.

369
00:37:08,668 --> 00:37:12,315
At the last moment, the bat
appears to lose track of the moth,

370
00:37:12,341 --> 00:37:15,257
and fails to catch it.

371
00:37:15,357 --> 00:37:19,768
We have shown that these moth
sounds actually jam the bat sonar,

372
00:37:19,805 --> 00:37:23,745
they interfere with the
returning echoes from the insect,

373
00:37:23,780 --> 00:37:27,419
and causes the bat
to miss the moth.

374
00:37:30,078 --> 00:37:33,603
The team has discovered that
insects are fighting back

375
00:37:33,614 --> 00:37:37,432
in the ongoing battle
for the night skies.

376
00:37:39,735 --> 00:37:45,501
But there are, of course, plenty of
other flying insects with no such defenses.

377
00:37:46,142 --> 00:37:48,864
and they live in vast
numbers in the forest

378
00:37:48,902 --> 00:37:52,518
outside Gomantong cave.

379
00:37:53,221 --> 00:37:56,263
So, every evening
as dusk arrive,

380
00:37:56,639 --> 00:38:01,993
the bats leave the safety of
their secluded home to hunt.

381
00:38:07,971 --> 00:38:11,434
And now, the bats are been in
use their echolocation skill

382
00:38:11,466 --> 00:38:15,331
to fly out from their roosts
in the depths of the cave,

383
00:38:15,352 --> 00:38:18,167
coming close to the ceiling
and then wheezing out

384
00:38:18,215 --> 00:38:21,308
through this little entrance here.

385
00:38:27,594 --> 00:38:30,728
They don't collide with the roof,
they don't collide with one another,

386
00:38:30,746 --> 00:38:33,486
or even with me,
all to that echolocation.

387
00:38:33,533 --> 00:38:36,155
There they go!

388
00:38:45,215 --> 00:38:48,725
But this is just a trickle,
the main exodus

389
00:38:48,752 --> 00:38:52,712
is taking place up a chimney
that's deeper in the cave.

390
00:38:56,885 --> 00:39:01,525
To watch close-up the way the bats achieve
their million strong mass departure,

391
00:39:01,541 --> 00:39:04,480
I'm being hold-up 200
feet into the tunnel

392
00:39:04,518 --> 00:39:07,525
which serves as one
of the cave main exits.

393
00:39:11,071 --> 00:39:15,189
At the top,
there is a gaping hole.

394
00:39:16,989 --> 00:39:20,530
And now, the bats are
preparing to leave.

395
00:39:27,704 --> 00:39:31,686
They have assemble in a relatively
small chamber close to the exit,

396
00:39:31,718 --> 00:39:35,891
and are flying round and round
in a great swirling crowd,

397
00:39:35,907 --> 00:39:38,811
waiting dor day light to fade.

398
00:39:41,467 --> 00:39:44,473
And now, off they go.

399
00:40:26,316 --> 00:40:30,555
This refire of dusk is the
moment when the two communities,

400
00:40:30,592 --> 00:40:35,991
the day flyers and the night flyers
may encounter one another in the air.

401
00:40:37,875 --> 00:40:40,821
Outside danger await,

402
00:40:40,853 --> 00:40:44,321
hunters belonging to that
other great group of animals

403
00:40:44,327 --> 00:40:47,019
with which their shares
the skies...

404
00:40:47,046 --> 00:40:49,732
birds.

405
00:40:50,910 --> 00:40:54,658
Hawks, Eagles and Kites.

406
00:41:01,444 --> 00:41:05,030
They are why the bats
were reluctant to leave,

407
00:41:05,071 --> 00:41:08,794
and why they now do so
in one continuous torrent,

408
00:41:08,846 --> 00:41:11,952
there is safety in numbers.

409
00:41:13,972 --> 00:41:17,437
But some will pay the price.

410
00:41:58,124 --> 00:42:02,829
The vast majority, of course,
make it out over the forest canopy,

411
00:42:02,857 --> 00:42:07,822
and there they can use that
skill of echolocation to find food.

412
00:42:24,885 --> 00:42:27,989
The way that different
animals have colonise the skies

413
00:42:27,996 --> 00:42:32,804
is surely one of the most remarkable
stories in the natural world.

414
00:42:38,604 --> 00:42:42,553
First to do so, over
320 million years ago,

415
00:42:42,565 --> 00:42:45,610
were the insects.

416
00:42:46,400 --> 00:42:50,334
They had no competition
for about 100 million years.

417
00:42:51,615 --> 00:42:54,975
But then, much larger flying
animals took in the air.

418
00:42:54,983 --> 00:42:58,188
Reptiles.
The pterosaurs.

419
00:43:00,634 --> 00:43:03,116
Around 70 million years later still,

420
00:43:03,148 --> 00:43:06,403
one branch of the
dinosaurs acquired feathers,

421
00:43:06,447 --> 00:43:10,373
and that enable their
owners to get airborne.

422
00:43:10,381 --> 00:43:13,566
The birds had arrived.

423
00:43:14,975 --> 00:43:18,171
And last in, about 60
million years ago,

424
00:43:18,229 --> 00:43:23,553
the night skies where
invaded by mammals, the bats.

425
00:43:25,174 --> 00:43:29,807
And here, in Gomantong cave, the
three surviving groups of flyers,

426
00:43:29,817 --> 00:43:32,202
insects, birds and bats,

427
00:43:32,234 --> 00:43:37,003
are still lock together in an
ongoing evolutionary struggle.

428
00:43:43,488 --> 00:43:46,251
So, the battle for the
supremacy of the skies,

429
00:43:46,273 --> 00:43:49,117
that started over 300
million years ago,

430
00:43:49,128 --> 00:43:53,866
still continues every
day around the world.

431
00:43:56,135 --> 00:43:59,471
Written and Presented by
David Attenborough

432
00:44:00,557 --> 00:44:05,089
English: Bobiko