Seven Worlds, One Planet

Australia -

an island continent

cast adrift during the time of the dinosaurs.

Isolated from the rest of life on land for millions of years,

the animals cast away here are today like none elsewhere.

This is a land of survivors.

The jungles of northern Australia - the oldest on our planet.

Unchanged for 180 million years.

The animals and plants here are armed...

...built to live alongside dinosaurs.

Now there is just one giant left.

With claws longer than a velociraptor and nearly two metres tall...

...the cassowary rules this forest.

BOOMING CALL

But the key to its success is not its stature...

...it's the male's abilities as a parent.

This one's chicks are six weeks old,

and he will raise them by himself.

Every morsel of food is valuable

if his chicks are to grow up tall and strong.

But in this forest,

most of the fruit is too big for the chicks.

It must be cut up for them.

There is food to be gathered throughout their territory...

...but it's not easy to find.

He shows them how to cross water.

But when your legs are only ten centimetres long,

a stream like this is very deep.

One takes the plunge...

...but for the other, this is too daunting.

He turns and goes back the way he came.

Out of sight and without his father's protection,

he's vulnerable.

Only half of cassowary chicks make it to adulthood...

...and for very good reason.

Australia's prehistoric forests are still full of predators.

CHEEPS

Many manage to survive here

by eating almost anything that's smaller than they are.

- He needs to find his father... - CHEEPS

...and quickly.

CHEEPS

The male hears his cries and answers...

...using a special call that carries well through the thick forest.

DEEP BOOMING CALL

And then, a glimpse of some reassuring, bright colours.

Their bonds are stronger than their fears.

The male will guide and protect his chicks for another eight months

before he mates again.

Australia was once part of the vast supercontinent of Gondwanaland...

- THUNDER RUMBLES - ...covered in forest and full of life.

Dinosaurs dominated.

Mammals had onlyjust appeared.

Then, Australia began to break away.

Cast adrift on this new island were reptiles, birds and early mammals

that then evolved in isolation from the rest of the world.

None could now leave this giant island,

and very few could get here...

...unless they could fly.

A little red flying fox.

Their ancestors flew here,

travelling along the chain of volcanic islands

that links Asia to Australia.

But their huge wings, which stretch from their fingers to their toes,

make it difficult for them to walk or take off from the ground,

so, when they want to rest, they hang upside down in trees.

But the bats have to drink every day.

And they do so on the wing.

They swoop just low enough to wet their bellies

and then, back in their roosts, they will suck out the water.

Each evening, 10,000 of them come here.

Not all of them return.

- Every two metres of river, there is... - BATS SCREECH

...a crocodile.

They were here long before the bats...

...survivors from Australia's prehistoric past.

These dramas have been taking place for millions of years...

...aerial agility...

...versus patience...

...and deadly speed.

Australia's forests are hostile places in which to make your home.

As you move inland, the forest thins, the air cools

and the land, as it gets higher, changes dramatically.

WIND BLOWS

The Great Dividing Range, 2,000 metres above the jungle.

To survive here, you must be able to tolerate really harsh conditions.

Kangaroos, like nearly all of the continent's native mammals,

are marsupials...

...mammals that rear their young usually in a pouch on the mother's belly.

And the young up here certainly need such shelter.

No kangaroos can survive for long, higher than this.

But there is an even tougher marsupial up here.

A wombat.

She usually shelters underground in a burrow,

but now that is under a metre of snow,

together with all the grass on which she lives.

She weighs as much a big dog

and has the legs of a small one -

not ideal for deep snow.

Fragments of bark hardly count even as a snack...

...and she's hungry.

She needs grass.

But it's over a mile away, across a frozen river.

Wombats might not be fast,

but then they don't need to be up here.

They can survive on next to nothing.

A few mouthfuls will be enough food for over a week.

And there's not much competition for it in this small corner of the continent.

Snowy peaks are hardly typical of Australia,

but the Great Dividing Range is a remnant

of what were once some of the longest mountain chains on Earth.

They connected Australia and Antarctica.

But then these sister continents broke apart.

Antarctica, drifting southwards, became locked in ice.

Australia drifted northwards towards the equator

and became hotter and drier.

Woodlands developed,

and in places where rainfall was low -

open grasslands.

On these grassy plains,

animals had the space to thrive.

These are also eastern grey kangaroos,

and this is their true home.

Here, they are well fed and powerful.

Adults can stand over two metres tall and travel as fast as a racehorse.

BIRD SCREECH ES

SCREECHES

And on these open plains, you need speed...

...because where there are large herds, there will be predators.

DINGO HOWLS

Dingoes - descendants of wolves that were brought here

over 4,000 years ago by human visitors from Asia.

This pack is led by a white female...

...and they are hunting.

Creating panic tests the herd.

Mothers with young in their pouches might be slower...

...but they can still outrun a dingo.

Maybe an ambush will work.

But even young, newly independent kangaroos seem uncatchable.

Across these open, flat plains,

the dingoes are just not fast enough.

But what makes the white female their leader is her stamina

and, particularly, her intelligence.

She has run 18 miles today, but she still doesn't give up.

A different group of kangaroos, this time on uneven ground.

It's what she's been looking for.

Driving them uphill, she's struggling to keep up with them.

And as they hurtle down the other side, the kangaroos pick up speed.

They will easily outpace her, if they stay in control.

The white dingo has more than one reason to be so relentless.

PUPS WHINE

She's a mother.

This is a rare sight.

Dingo pups are hardly ever seen.

With so much effort forjust one meal,

the open plains are tough places on which to raise young.

These are gumtrees.

They have leaves that are poisonous to most animals.

But not the koala.

They eat almost nothing else.

There are echidnas in these forests, too -

mammals that don't even have pouches but lay eggs like reptiles.

And there is an assassin here that has only recently been discovered.

AJotusjumping spider.

She's only five millimetres long,

but nonetheless she's a stealthy and ferocious hunter.

She searches for prey among the grass stems.

She's single-minded and focused on hunting.

But today might be different.

This is something new,

something fast...

...and a little trickier.

But what is it?

Is it food?

It's a maleJotus, looking for a mate.

He needs to catch her attention,

but femalejotus only mate once.

If she's mated before, she might kill him.

He will need to seduce her with care.

Waving his arms makes his intentions clear.

He's a friend, not food.

No sign of an attack...yet.

But she doesn't seem particularly impressed.

Time to try his best move...

...the double paddle.

That surely will do the trick.

One final wave...

...and he's tamed her.

She stays still forjust long enough.

And then he retreats quickly, before she has second thoughts.

If you travel still further towards the centre of Australia,

the landscape changes yet again.

Trees and grass disappear.

The continent, throughout prehistory, continued to drift north