All language subtitles for Attenboroughs Big Birds BBC Natural World 2015 720p HDTV MVGroup EN Sub_Subtitles01.ENG

Birds are masters of the skies.

There are more than 10,000 species

and they behave in a huge
variety of different ways.

But of all the birds
I've filmed over the years,

there's nothing that can really
compare with these comic characters.

That's not just because
of their great size.

But because they can't do
the one thing

that birds are famous for doing.

They can't fly.

The ostrich, the emu and the rhea,
together with two other birds,

the kiwi and the cassowary,

are the court jesters
of the avian world.

They're a family with
a remarkable success story,

despite having never flown
a day in their lives.

But exactly how and why did
these birds abandon flight?

It's one of the natural world's
great mysteries

and it's taxed some of
the finest minds in science

from Darwin's time right through
to the present day.

And now, DNA is promising
to give us the answer.

But what is even more exciting

than the remarkable evolutionary
history of these birds

is their behaviour -

because if you're a bird
that can't fly,

you have to find other ways
of surviving.

BIRDSONG

It's said that a bird
is three things -

feathers,

flight

and song.

BIRDS CHIRP

But what happens
if you are a bird which can't fly,

which doesn't sing...

HISSING

..and whose feathers are closer
to fluff?

Well, then you have to come up with

some pretty unusual ways
of surviving.

This small group of birds
are real oddballs,

with a rag bag of characteristics

that help them
with life on the ground.

Among their number
is the fastest bird on land.

A bird with the biggest eyes
on Earth.

One has dagger-sharp talons.

Another, killer thighs.

OSTRICH HISSES

Their chicks hatch, ready to run.

CHICKS GRUNT SOFTLY

And they all have crazy hair.

And useless wings.

This lot couldn't fly
even if they wanted to

because their feathers
aren't like those of other birds.

They don't have barbs that link
together into air-cutting vanes,

like normal wing feathers.

Nor can they be held neatly
and tightly together.

They are more like
a fluffy feather boa.

Without a role in flight,
these feathers act instead

as warm blankets or insect repellers

or props in an exotic dance.

But if you are a bird
that hasn't flown a day in its life,

then beauty isn't enough to survive.

The first, the fastest
and the biggest of all our birds

is the ostrich.

OSTRICH BOOMS

Indeed,
it's the largest bird in the world.

Standing up to 3 metres tall,
it weighs up to 150 kilos.

On the African plains,
it lives alongside

some of the world's most
dangerous predators...

..hyenas...

..lions...

..and cheetahs.

BIRDS CHIRP

DRAMATIC MUSIC

Pounding across the plains,

it uses its powerful legs
to run for its life.

DRAMATIC MUSIC

Adult birds can run at speeds

of up to 70km -
over 40 miles - an hour,

covering almost 5 metres
in a single stride.

DRAMATIC MUSIC

DRAMATIC MUSIC CLIMAXES

This young ostrich
hadn't quite developed

the power or agility needed

to escape these speediest
of predators.

But it still took the combined skill
and experience

of a team of cheetahs,
working together,

to bring the young ostrich down.

CHEETAH GROWLS

This is, nonetheless,
a remarkable and very rare sight.

CHEETAH PANTS

Most ostriches escape
from such attacks.

Adult ostriches are powerhouses
of strength and agility

and are seldom caught by predators.

BIRDS CHIRP AND WHOOP

The second of our birds
also has size and speed on its side.

But for the biggest bird
in South America,

there is danger of a different kind.

LATIN GUITAR MUSIC

This Argentinian rhea
has grown big -

indeed, bigger than most of
the mammals that live here.

But this male has nonetheless
to remain alert...

..from attacks
from one of his own kind.

It's the beginning
of the breeding season

and males are starting to spar,
sizing up their rivals' strength

before the real battle to breed
begins.

RHEAS GRUNT

MUSIC CONTINUES

To the winner, TWO females.

But although this fight
has been won,

the coming war will doubtless
see him forced to defend his gains.

CRICKETS CHIRP, INSECTS BUZZ

DIDGERIDOO PLAYS

Here in the Australian outback

roams the second-largest
of our big birds,

the emu.

A nomadic character, he uses
his spectacularly elongated legs

and ferocious-looking feet
to go walkabout...

..meaning he can cover
vast distances

in search of food and water.

BANJO PLAYS

Emu truly are wanderers -

always on the move,
following the rains,

they walk hundreds of kilometres.

And when they find water,
they take on board all they can.

BIRDS CHIRP, INSECTS BUZZ

But flightless birds in Australia

aren't restricted
to the parched outback.

In the tropical rainforests
in the north of the country

lives another one.

It stands almost 2 metres tall
and has a dinosaur-like crest

and dagger-sharp claws
that give it a lethal kick.

DRAMATIC MUSIC

Cassowaries are
fiercely territorial.

And one will fight to the death
to defend itself

or its magnificent
emerald-green eggs.

Like the rest of his family

in Africa, South America
and Australia,

it's a bird which has taken
an evolutionary route

very different from that
of its aeronautical relatives.

Cassowaries vary
greatly in colouration.

So, it's debatable
how many species there are.

Probably three.

Another flightless bird
lives in New Zealand,

hidden in the forests
and only active at night.

It could be called
the runt of the litter.

Standing only
a half a metre or so tall,

this is a kiwi.

More like a mammal than a bird,
it has dense, hair-like plumage

and a very long,
very sensitive beak,

which makes up for its tiny
and all but useless eyes.

It walks along like a little hobbit,
with its arms behind its back.

When, in the 19th century,

tales of the kiwi reached
naturalists in England,

they thought them merely figments
of early travellers' imaginations.

One of the largest collections
of this weird walking family

was amassed by a Victorian English
eccentric, Walter Rothschild.

Collectively, these extraordinary
birds are known as the ratites,

flightless birds
that just grew and grew,

from the smallest -
that's the kiwi -

to the largest alive today,
the ostrich.

But their ancient relatives
were even more impressive.

Enormous birds that would have
towered over me,

like the moa from New Zealand

or the elephant bird
from Madagascar.

But exactly why did these birds
abandon flight?

Well,
flying is a very energetic business,

much more so
than walking or running,

and birds don't fly
unless they have to.

WAVES CRASH
Some, like penguins,

gave up flight relatively recently

and took to the water.

But they still have strong wings,

which they use like paddles
for swimming.

The ratites are different.

They are the original
flightless birds.

And they're the only birds
whose skeletons

make them incapable of flight.

Hidden beneath their mass
of feathery fluff

is a flat, raft-like breastbone

that lacks the ridge onto which
flight muscles can be attached.

In fact, it's this which
gives them their name,

from the Latin word,
"ratis", meaning "raft".

So, whilst there are other birds
which don't fly,

our very special family,
the ratites,

stand entirely apart
from all the others.

They are the Flintstones
of the bird world,

a group whose lineage can be traced
back to the time

when dinosaurs walked the Earth.

The dinosaurs
once dominated the land,

just as their relatives,
the pterosaurs, ruled the skies.

But when, 66 million years ago,
both groups were wiped out,

some of the ancient birds
seized their moment

and made a bid to dominate
the land themselves.

Some, the ancestral ratites,
grew big and fat,

with long, strong legs,
until one day,

they were too heavy to fly.

Since then, of course,
the mammals have fought back

and in most places, THEY won.

But the elephant bird
and the moa, now extinct,

survived until a few centuries ago

and five others still flourish
across the southern hemisphere.

The ostrich, the emu,

the cassowary, the rhea

and the kiwi.

BIRDS CHIRP, INSECTS BUZZ

The success of the ratites today
is largely due to

some bizarre breeding
and very complicated relationships.

Males mating with multiple females,

females mating with multiple males,

fathers raising chicks
which aren't theirs.

The tenacity and endurance
of these dedicated dads

has helped raise generations
of walking giants.

So, how do our motley crew ensure
the survival of their offspring

when safe tree-top nests
are out of the question?

Well, it takes a lot of work.

For the emu
in the Australian outback,

the breeding season
starts in the winter.

This is when a male needs
to be at his heaviest.

DIDGERIDOO PLAYS

Large bodies enable ratites
to develop large guts,

so unlike small flying birds,

they can stock up
on plenty of plants and seeds.

Soon, he will mate and he will be
the one who will incubate the eggs.

During his time on the nest,
he won't eat or drink.

So, he's preparing for that
by fattening up.

This time of the year
is all about finding food

and some enterprising males

even go into town to pick up dinner.

CAR HORN BEEPS

BANJO PLAYS

TRUCK HORN BEEPS

A strange sight -
but the locals are used to it.

TRUCK HORN BEEPS

When they are ready to breed,

male ratites start to try
and impress females

and they do so with some pretty
flamboyant dance moves.

Ratites might not be strong
contenders in a beauty contest

but these males certainly know
how to move and groove.

From the ostrich to the cassowary,

the males all work hard
to show off their best features.

Just HOW hard can be seen
on the grasslands of Argentina.

It's spring and the rheas are
preparing for the breeding season.

Male rheas, with their distinctive
black markings, have broken away

from the flocks in which they spend
the rest of the year.

Now is the time for courtship,

when their feathers will be
shown off in all their splendour.

As ratites no longer fly, they have
no gland to produce the oil

needed to preen their feathers into
continuous air-catching services.

But with a little grooming,

their plumage can be
very impressive.

This male has managed to secure
several females for himself.

Herding them
with his outstretched wings,

a male can maintain a harem
of anything from two to ten females,

as long as he can keep them close.

He doesn't let them
out of his sight,

courting each one in turn.

And the grand finale
of his mating ritual...

..this curious head-bobbing dance.

It's hardly a tango.

And the object of his affections
doesn't seem particularly impressed.

But despite the lack
of encouragement,

he will spend most
of the breeding season

herding and head-bobbing
to his females,

until they are ready to mate.

Unless, of course...

..this rival male can rob him
of his hard-won harem.

Rising up as high as he can,

he puts on a show
of size and strength.

This performance
has rarely been filmed.

It's a tango of a different,
aggressive kind

with plenty of
Latin American spirit.

Today, there is someone
better than he.

He retreats, leaving the rival male

to take his place
on the dance floor.

This male is, it seems,
a little more persuasive.

Exactly how ratites mate

was a mystery only solved
by scientists

in the last few years.

Most birds don't have a penis.

Instead, both the male
and female birds

have an opening called a cloaca.

That certainly helps to streamline
the body of a flying bird.

The male ratite, however,
is different.

He does have a penis,

and it was once assumed
that these large birds

would have blood-based
erection systems,

similar to humans.

But in fact the ostrich,
emu and rhea

enlarge their penises
with lymph fluid.

They also have a few additional
muscles to keep everything in place.

While it's known that male
and female rheas will mate

with several different partners over
the course of the breeding season,

there is much less certainty
with another of our ratite family.

On the islands of New Zealand
lives an enigma.

The most secretive
of our flightless birds.

Hidden in these ancient
and mysterious forests,

it only emerges after dusk.

HIGH-PITCHED BIRD CALL

Only in the pitch-black dead
of night does it call.

HIGH-PITCHED CALLING

Ratites might not sing,

but their mating calls
are certainly piercing.

This is a bird which is heard
but seldom seen.

Scientists have to struggle
to catch sight of the kiwi,

let alone to understand
its behaviour,

even when they work
around the clock.

But using infrared light,
which the kiwis can't see,

and radio transmitters
to track them in the darkness,

the researchers here
are slowly piecing together

a picture of this shy bird.

For the last 11 years,

I have been looking at
the breeding behaviour of Kiwi

and everything that is
associated with it.

Dr Isabel Castro
is a Colombian expert on kiwis

who has lived in New Zealand
for the past 25 years.

This environment where they are

is completely different
than our environment.

They are nocturnal
where we are diurnal,

and for many years
before we started this research,

people thought that they had
this relatively boring life

and yet as soon as we started
this project,

we started finding out
these fantastic things

about their intimate life.

There have been all sorts of things

that were completely unexpected,

and that made now these birds
very extraordinary,

because we didn't know
those things before.

Living in complete darkness,

unable to see virtually anything,
the eyes of the kiwi

are all but useless,

but - unusually for a bird -

it's got a great sense of smell,

which it uses to find
its way around.

By setting up remote cameras,

the scientists have been able
to capture behaviour

never filmed before in the wild.

Two males fighting.

KIWIS RASP

A female calling for her mate.

REPETITIVE GUTTURAL CALL

Males and females
have different calls.

The females have this very coarse,
grunty call,

as all females should have, you know!

The males have these whistles,
beautiful and piercing.

REPETITIVE SHRILL CALL

Isabel and her team even managed
to film a kiwi family

with a tiny chick.

Kiwis are the only nocturnal ratites

and by far the smallest.

This big bird isn't big at all.

It only weighs about two kilos.

Kiwis never grew big

because they lived alongside
the now-extinct moas.

With those giant herbivores
already roaming New Zealand,

the kiwi's evolution
took an alternative path.

It remained small,
became nocturnal and omnivorous.

With nostrils at the end
of its beak,

the kiwi sniffs out insects
and worms at night...

..and then stays in the safety
of its burrow for the day.

Unlike the other ratites,
it nests underground.

Until recently, it was thought that
kiwis bred in monogamous pairs,

but now DNA analysis has painted
a much more complicated picture.

They are very naughty, kiwi.

For a long time, we thought
that they were really good birds,

and mated with one another,
one male, one female,

but they are not like that at all.

They do stray a little bit.

They do stray.

It seems that breeding is a little
more flexible than just one-on-one.

Some birds seem to breed
in family groups.

Others may raise young as a pair

even though the chicks
might not belong to Dad.

However, it's the males who shoulder
the burden of incubation.

The eggs in their care
are among the oddest on earth.

This is a kiwi's egg.

It's the biggest in proportion
to body size of any bird's egg.

It weighs about a fifth

as much as the adult bird.

It's so big,
it takes 80 days to incubate.

The Maoris used to say

that tree routes would grow over
a kiwi's nest.

This is the egg of another ratite,
an ostrich,

and curiously, it is the smallest
egg in terms of body weight

for any bird in the world.

These ostrich eggs
are unusual in other ways.

They too are part of an elaborate
game of pick and mix...

..because ostriches
are almost like cuckoos.

Females will lay in the nests
of other ostriches,

but unlike the cuckoo,

the owners of the nest know about it

and they don't seem to mind.

It may help to have
a few spare eggs.

The female seems to be able
to recognise her own eggs,

keeping them at the centre of
the nest while rolling out others

as sacrifices to any predator
brave enough to make an attack.

Up to six female ostriches
may lay in a single nest.

For most members
of the ratite family,

the rhea, the emu
and the cassowary,

incubation is something
of a gentleman's club -

females aren't welcome.

But the ostrich does things
a little differently.

The male and female take turns
at caring for the clutch,

keeping watch by day and night
to make sure

nothing has a chance
to steal the eggs.

This father-to-be is carefully
rolling the eggs to make sure

the embryo inside
gets evenly warmed.

In the cold of the night,

he uses his feathers as a blanket
to cover his charges.

Communicating by clacking
their beaks,

this couple share
the parental burden.

They take turns to sit on the eggs,

which, although small
compared to the ostrich itself,

weigh in fact almost two kilos each,

the largest eggs laid
by any living animal.

Left unattended, such large eggs
soon attract attention.

These ostrich eggs
are giant ready meals

for a variety
of African animals.

You can't make an omelette
without breaking eggs,

and this jackal has worked out just
how to crack one against another

and so release his lunch.

The Egyptian vulture has its own
ingenious version of smash and grab.

It's perhaps not surprising

that up to 90% of ostrich clutches

are totally destroyed.

In South America, rheas nest
in a similar way to the ostrich.

For two weeks, females lay their
eggs in one shallow, communal nest.

Each egg is 12 times
the size of that of a chicken.

But unlike the ostrich,

it's the male who settles down
to do all the hard work.

He alone will incubate these eggs,

and he does so for more than five
weeks, whatever the weather.

THUNDER CRACKS, HEAVY RAIN

It's an arduous task.

65% of males abandon their nests,

many because they don't have the
energy to sustain themselves

without going away to feed.

The females, however, never put
all their eggs in one basket.

Once they've mated
with this one male,

they move on to another,
so increasing the chance

that at least some of
their young will survive.

Nesting on the ground
out in the open

means that, inevitably,
the eggs are vulnerable.

From the enormous
eggs of the ostrich...

..to the green eggs of the emu.

But for one of the relatives, the
battle to keep their clutches safe

was, in the end, lost.

These are the leg bones
of the elephant bird.

It was the largest of the ratites.

Indeed, it was one of the biggest
birds ever known.

It stood over 3m tall and
weighed half a tonne.

It lived on the ancient
island of Madagascar,

which I visited over 50 years ago.

Before Europeans ever
went to the island,

it had a reputation
for being the home

of really strange, fabulous beasts,

and Marco Polo, 700 years ago,

believed that it was the home
of the fabulous bird, the rukh.

The rukh, which carried off Sinbad
the Sailor, and which was reputed

to be able to carry off
elephants in its talons,

as this one is doing.

But Marco Polo had very good
reason for thinking that it
lived in Madagascar,

because he heard stories that in
Madagascar were found gigantic eggs,

over two feet long. What else could
have laid them but the rukh?

Well, I was lucky enough to find

some pieces of the rukh,
or elephant bird's egg.

And even luckier to be given some
pieces that looked like

they might belong to one egg.

Now, would they fit together?

These two certainly did.

At the end of an hour,
I had two halves.

And to my joy,
they fitted together perfectly.

There was a place for even such
a tiny fragment as this.

The egg was well nigh perfect.

As I held it, I had little
difficulty in imagining the country

as it must have been when great
numbers of gigantic birds,

over ten feet tall, strode
majestically through the swamps.

This is the egg that I brought back
from Madagascar all those years ago.

It's the biggest egg ever
laid by anything.

Bigger by far than even
the egg of the biggest dinosaur.

As you might imagine,
it could have made a meal

for quite a lot of people,

and that may well be,
some people think,

the reason why the elephant bird
became extinct.

If it wasn't for human beings,
the elephant bird might still

be walking around on Madagascar.

The same fate met
the moas of New Zealand,

some kinds of which
weighed over 200 kilos.

The elephant bird might have been
the biggest bird ever to exist,

but some think that one species
of moa was the tallest.

Moas, too, were hunted
and had their eggs eaten by humans

until there were none left.

We know this because of the careful
detective work scientists

have done on their bones.

It's not the only puzzle

that fragments of extinct bird like
these, of the moa,

might be able to solve.

If these birds were flightless,
how did they manage to spread

round the world,
from the deserts of Africa

to the rainforests of Australia?

It's a conundrum that has puzzled
minds for centuries.

Not that long ago, scientists
thought they had the answer.

All the places in which
the ratites lived

had once been part of a
supercontinent called Gondwanaland.

Perhaps our birds came from one
common ancestor, which was

also flightless, that roamed
all over that land.

Then, millions of years ago,
when the continents split up,

populations of this bird
were separated.

As their homes drifted
into new positions,

the isolated birds adapted and
evolved in different ways,

producing everything
from the tiny kiwi

to the huge extinct elephant bird.

But ancient bones are telling
a different story.

Scientists have recently been
sequencing DNA

from the bones of extinct ratites

and compared them
with living flightless birds,

and the results have come
as a huge surprise.

The mighty elephant bird,
which should be most closely

related to the ostrich, turns out to
be most similar to the tiny kiwi.

Not what was expected at all.

So how could this possibly be?

Well, an unexpected character
is providing some answers.

A little-known ratite relative,
the tinamou,

that lives in Central
and South America.

DNA has recently revealed that it
isn't a distant relative,

a cousin, say,
but instead a sibling,

smack in the middle of
the ratite family tree.

Which is remarkable,
because tinamous can fly.

Now, if all the ratites and
the tinamous evolved

from one flightless ancestor,

then the tinamous must have
relearned how to fly.

But there are no known examples
of a species of flightless bird

regaining flight,
so this suggests

that the common ancestor of the
ratites and the tinamous

wasn't flightless at all.
He could fly.

Our birds might not have
drifted away from one another

on the lands
in which they live today.

Instead, their ancestors must have
flown across miles of ocean

to reach the far corners
of the world, and only then

did they independently lose
the ability to fly.

It's an amazing thought,

but the ratites lost their ability
to fly independently

and on several different occasions.

Thousands of miles apart from each
other on their separate continents,

each kind of ratite developed
into its own flightless form.

The ostrich and the rhea
kept their wings

and evolved elaborate uses
for their feathers.

The wings of the emu and
cassowary became short and tiny...

..and the kiwi, well,
its wings are now all but invisible.

Although the details are different,

the demands of living on the ground
meant that all the ratites

evolved in their own way
into flightlessness.

And there's one survival strategy
which they all share,

and which begins when they hatch.

In the Australian outback,

this male emu's hard work over the
past 56 days is about to pay off.

He is a father.

His chicks, like all newly hatched
ratites, are able to get up and go

almost from the moment
they break free from their eggs.

This is an invaluable ability
for a chick,

which is, after all,

a very succulent mouthful
for almost any predator.

Emu chicks, with their tawny
markings, are known to Australians

as stripeys.

Their dedicated dad will spend
the next six months caring for them,

by which time they will already have
grown to at least half his height.

That is, if they ever
hurry up and hatch.

The chicks had to work hard to free
themselves from the egg shells.

Now they need a drink.

Their father must face
a tough decision.

One egg still hasn't hatched.

If he stays and waits for it to do
so, the older chicks may die.

It's likely that he can hear
sounds coming from within

the unhatched egg.

Meanwhile, the harsh Australian sun
scorches down on those

of his offspring desperately
waiting for their first drink.

After many agonising hours,
he makes his choice.

Leading the brood to find water,

this father helps a new generation
of big birds take their first steps.

From South Africa to South America,

an extraordinary combination
of mating behaviour

and parental care has produced birds
which are very special indeed.

CHIRPING

These young ostriches will soon grow
into the biggest birds in the world.

Although today, as they take tiny
steps across this vast landscape,

that day seems a long way off.

The next generation of ratites.

A reminder of how one remarkable
group of birds independently

seized a moment when there were no
predators around to hunt them down

and set off down various but similar
evolutionary paths.

The only group of birds to have
become massive and flightless.

It wasn't long before some mammals
also became big and dominant,

and when they did,

the window of opportunity for more
birds to do so closed.

But what an opportunity it was,

and those birds which took advantage
of it are truly remarkable.

Scientists are currently working
to gather still more clues,

from birds both extinct and living,
to add even more detail

to their amazing
evolutionary history.

We can only hope this will help us
to better understand

this family of birds,
which are surely flightless wonders.