Original subtitles

On Australia's highest peaks, the snowy mountains,

winter temperatures reach well below zero.

This true alpine wilderness can spend half the year beneath a blanket of snow.

Very few creatures can withstand the winter on Australia's peaks, where food is scarce.

But some tough it out.

This echidna has hibernated on and off during the coldest

months, emerging at the tail end of winter very hungry.

An insect eater, it's slim pickings while the snow encases his food source.

But as one of those energy-efficient mammals on the planet, with a body

temperature that can drop below five degrees Celsius,

this echidna can survive long periods in the bitter cold.

His shovel-like claws work like snowshoes.

It's a lonely march on an empty stomach.

As the days get longer and warmer, high country

rivers carry the now liquid winter down the mountain.

Spring's arrival also means, at last, the echidna

can feast after months of winter's famine.

But one obstacle still stands in the way of a full belly.

A fast flowing one.

Using his long beak as a snorkel and large feet as

paddles, he's perfectly capable of a river crossing.

He may not look like an all-terrain vehicle, but the echidna inhabits more

Australian landscapes than any other native animal.

He will now spend 18 hours a day foraging for

insects, turning over soil and gardening the forests.

The echidna is named after the Greek goddess

Echidna, who was half woman and half reptile.

Its closest relative, the world's only other

monotreme, also has a curious blend of characteristics.

With splayed limbs, on land, the platypus shuffles like a lizard.

But in the water, she glides like an otter.

Egg-laying and beaked like a duck, she's the ultimate man-eater.

But the

combination works.

The platypus has remained unchanged in Australia for 25 million years.

These elegant underwater hunters are the

oldest lineage of mammals alive on Earth today.

Living only here, on the rivers of eastern Australia.

Later on the evolution of the world, the platypus will be the only one to survive.

But in the same surrounding grasslands and

forests of modern Australia are the marsupials.

And the most familiar of them all is the eastern grey kangaroo.

The weight of an adult human, but head and shoulders

taller, this male is demonstrating his potency to the mob.

A thick, sticky secretion from glands on his chest, in a cocktail of fresh urine,

says, this is my patch.

Just in case anyone doubts his authority.

He has a harem of nine breeding females.

All with at least one, Joey.

Despite the male's posturing, he's not the powerhouse

of this extraordinarily successful species.

It's the female with her magic pouch.

So while this ten-month-old Joey is starting to explore the outside world,

another tiny baby is already developing in the pouch.

It's only the size of a jelly bean.

The older Joey is now being forced to spend more hours outside the pouch.

To give his mum and new sibling a break.

Like all young ones, he knows to keep pestering until she gives in.

He's a little bit of a snob.

With only two Joey's on the go, she's now ready to fall pregnant again.

A fact not lost on the dominant male.

He will pursue her for days.

But rival males are a constant threat.

Maintaining his status as top roo is so taxing, that he may only keep the dominant

male crown for a year before he is toppled.

Being a kangaroo is much more complicated than it appears.

But the energy expended on reproduction is working for them.

Exploiting the farmlands which have spread across the continent, there are millions

of eastern grey kangaroos in Australia today.

Large kangaroos are amongst the very few native animals to benefit from land

clearing and the decline of Australia's apex predators.

So many species are gone now.

The continent's top carnivore, the Tasmanian

tiger, was hunted into extinction by the 1930s.

And the grand hunter from the skies, Australia's

own eagle, has come perilously close to being lost.

This country's wedge-tailed eagle is one of the world's largest.

For years it was mercilessly shot, mistakenly

portrayed as a prolific killer of lambs.

In the mid-1900s, there was a bounty on its head, with up to 30,000 eagles.

The eagles killed in a single year, their great bodies strung up on fences.

Eagles are now protected, and most farmers accept

that they are no threat to their livestock.

Now affectionately known as wedgies, their calls again echo across the farmland.

Australia's biggest bird of prey has a chance of a comeback,

thanks in part to another mistake of European settlers.

Fluffy eagle fodder, brought here over 200 years ago, now in plague proportions.

The wedge-tail is a stunning avian predator.

But such a large bird, her movements are deft and light.

With a 2.5 metre wingspan, her precision at speed is breathtaking.

She can soar up to 2,000 metres high, and carry

half her own body weight in her huge talons.

But as she surveys the landscape, those eagle eyes

pick up something curious, and worth investigating.

An eastern long-necked tortoise.

Although the tortoise has almost impenetrable

shell, he's not taking his chances.

Time to retreat.

She's sure that rock was moving.

But it's not.

Baffling, really.

It's an old trick, but a good one.

The eagle resumes her search for an easier target.

This time, it's more familiar.

In some parts of the country, rabbits make up 90% of the eagle's diet.

The tortoise... zero.

Yet again, the tortoise bids their.

And eagles now are the farmer's friend, helping to keep the rabbit population down.

Before rabbits were introduced to Australia, and so much native bushland was

removed, it was the small native animals which had the run of the land.

In the southwest of the country, lie the dryandra woodlands.

This stand of wandu eucalyptus is one of the last strongholds for a native mammal,

which once roamed the entire continent.

As the sun hits the carpet of wildflowers, and insects begin massing on the forest

floor, a small marsupial, a male marsupial, is making its first move.

The numbat.

Closest living relative to the extinct thylacine, or Tasmanian tiger,

is on a termite hunt.

It will take 20,000 termites to fill her belly.

Back in her den, are four rapidly growing numbat

pups, which she has fed through the night.

The young are eight months old, and only just

getting curious about life beyond the burrow.

One of them, the smallest and boldest, is the leader.

She's begun to explore the tree stump fortress, protecting the burrow exit.

Her siblings follow, trembling as the air hits their fur.

Each day, our leader has inched closer to the fortress walls.

From here, she gets her first glimpse of the world beyond.

But with every sound of warning, the pups retreat, more than advance.

They'll do well to be cautious.

Hundreds of thousands of numbats once ranged across Australia.

Today, there are less of them than the more famously endangered snow leopard,

or giant panda.

Just like the panda, numbats are specialist feeders,

needing something that's now in very short supply.

Undisturbed woodland, with logs for termites.

This female can smell a termite's gallery, and

even feels their tiny vibrations beneath her feet.

Using her worm-like tongue, she extracts them from tricky crevices.

Each day, she swallows 10% of her own body weight.

Her young are getting braver and reveling in the sun.

The rounded snouts, which have suited milk

feeding, are getting more elongated by the day.

Within a month, they too will be reliant on termites.

So the job of working out what is food and what is not, is the lesson of the day.

Except for one of them.

Our little explorer is determined to experience what lies beyond the wall.

While her siblings stay cautiously close to the burrow.

She takes off.

She will keep wandering further from the burrow, until one

day, she leaves her mother's territory and finds her own.

Crossing paths with other young numbats, also emerging from hollows in this forest.

Each one of them will need to venture and breed in order to keep this species viable.

Over the past two centuries, almost all of the numbat's habitat has been destroyed.

Apart from these last stands, a whole new forest.

And less than one thousand tiny numbats are left surviving in the wild.

Where Australia's ecosystems are left intact, animals thrive.

It's as simple as that.

In far northern Queensland, the rainforests of the wet

tropics appear as a thin ribbon of green along the coast.

These rainforests have been around longer than any other on the planet.

An estimated 180 million years.

Far outdating the Amazon.

Australia's most secretive and unique creatures have made the forests their home.

And everyone here is competing for spoils.

Even on the forest floor.

Thousands of species of fungi battle to dominate the leaf litter.

Despite their myriad forms, the fungi are all engaged in similar biological magic.

They break down wood and leaf litter and return their nutrients to the soil.

While slime molds hunt down the fungi and turn them into nutrients too.

Things live fast and die young on this forest floor.

The

pioneers of recycling, you might say.

Assuming every imaginable shape.

They feed the hungry forest, turning it into

one of the Earth's evolutionary hotspots.

For it was here, in the cradle of the Gondwana

rainforests, that Australia's mammals first emerged.

As the land became more arid, many moved out to the grasslands.

But there is one kangaroo which has never left its rainforest home.

A shy creature, rarely seen on the forest floor.

That's because its home is in the trees.

This young male tree kangaroo has evolved for a life in the canopy, with large

strong arms, big curved claws and a pendulous tail.

But even 20 meters up, he's still clearly a kangaroo.

The

monkey of the kangaroo world, just a little less sure-footed.

At almost two years old, he's only recently left his mum to find his own territory.

Unlike his relatives at ground level, he will live a solitary

life, only seeking out a female when it's time to mate.

But he's having trouble cutting the umbilical cord.

He can hear his mum in one of her favorite trees,

and he crosses the canopy roof to reach her.

But it's not a tender welcome.

His mother doesn't want him near her.

They move to opposite ends of the tree.

Her tough love suddenly makes sense.

At eight months, the newest joey has begun leaving

the pouch and exploring her high-wire world.

Oh, she's wobbly enough.

A teenage sibling might topple her altogether.

For her brother, being solitary requires its own process of evolution.

At least up in this rainforest, he's never really lonely.

Above and below him, over half of Australia's bird

species are in a springtime nest-building frenzy.

The sunbird uses bark and seeds to build its hanging nest.

And the form-breasted bowerbird makes final

artistic touches to its elaborate construction.

Most cockatoos and parrots rely on hollows.

It would seem an easier option than DIY.

But relying on hollows has left the parrot world out on a limb.

This female eclectus parrot has guarded her hollow well before she was ready to lay.

Her green mate delivers food to her so she can stay on sentry duty.

Hollows form slowly in old trees, so there's never enough to go round.

Unlike so many in this forest, this one is too

high to flood and it's safe from predators.

It should be a textbook in keeping with the nature.

But

the neighbours nobody wants are looking to move into this leafy suburb.

It's the sulphur-crested cockatoo.

Famously loud, assertive and ready to lay, this pair want the hollow for themselves.

They begin a game of intimidation.

Unlike the cockatoos, who can breed three times a year, the

eclectus parrot is doing well to raise one chick annually.

But as the day heats up, temperatures

inside the nest hit over 30 degrees Celsius.

Her ovaries, her own body heat, is raising temperatures even further.

Her eggs will cook in this oven.

With the coast clear of sulphur-crested

cockatoos, she leaves to let the nest cool down.

But they see an opportunity too.

If the cockatoos get inside, they will smash the eggs.

The cockatoos get more confident with every passing moment.

The female will fight to the death to protect her eggs.

Her siren colour is enough to ward off these intruders.

But colour is only one of the many ways birds in this forest communicate.

It's only recently been discovered that 24 million

years ago, birdsong evolved in this forest.

It is the home of nature's great vocalists.

It's also where one cockatoo has developed a sound

so unique, it wasn't thought possible for a bird.

The continent's largest cockatoo.

The palm cockatoo, or palmy.

It's the most intelligent of Australians and possibly the world's bird species.

Its brain is comparable in brain-to-body ratio to that of a dolphin or great ape.

But it's also a parrot.

And like its relatives, the palmy nests in tree hollows.

This proud pair have secured a beautiful bough.

And for their entire lifespans, around 60 years, they will share the parenting.

They pass the baton with a kiss.

Before taking turns to forage.

These birds in this forest have evolved together.

With one of the world's largest beaks, they're amongst the few creatures able to

break into the hard fruits of the native nonderplum.

As the female returns to the nest, she offers a distinct knock.

To say, it's me.

But it is her mate who works harder still to message his partner.

Communicating in a way no bird, indeed, no other animal on earth has accomplished.

This male palmy has a talent long thought exclusively a human skill.

He fashions a drumstick and very carefully and very deliberately makes music.

Each male produces regular beats to his own particular rhythm.

Why he does this is still unclear.

Is it a show of strength to ward off competitors?

Or a message to his partner that she needs to look no further.

He and his nest are best.

A feature of Australia's tropical rainforests is their stability.

But the monsoon region to the west is volatile and unpredictable.

Here the land seesaws between two extremes.

The floods of the summer's wet season.

And the raging fires which can take hold burning

for months through the region's parched winters.

But it's these extremes which have helped sculpt

some of the world's most dramatic landscapes.

One of the largest savannas on Earth

sweeping across one quarter of the continent.

Intersected by permanent tidal rivers.

The hunting ground of the saltwater croc.

This male known to the river guides as Casanova

has been top croc on this river for decades.

With over 60 pointed teeth.

And while now in his late 50s he might be

considered an old croc he has learned a new trick.

Casanova has adapted to the presence of humans in an unexpected way.

He associates the rumble of a boat crammed with tourists with dinner.

Life jackets.

Yep, they're situated just up there.

I'm not even going to show you how to put one on.

Does anyone know why?

Yeah, crocodiles are attracted to bright colours, OK?

And splashing.

So, um... And there's about 5,000 crocodiles in this river.

If you end up in the water you won't have time to drown anyway.

Yeah?

So, number one, avoid going in the water.

But, um, if we do, life jackets are useless.

When not chasing the female crocs Casanova puts

his natural abilities to good use and thrills them.

And she kills the tourists.

A wave-like thrust created by hundreds of muscles working in tandem propels

two-thirds of his body clear from the surface.

Finishing the leap with a bite.

The strongest downforce of any animal.

Although it looks unnatural crocs will leap for animals on overhanging trees.

She's ready to go now.

Look at this.

No mucking around.

Here we go.

Here we go.

All right.

There we go.

Only here in Australia have Casanova and his salty river

mates learnt to jump for rewards offered up by humans.

To avoid a crocodile attack's very easy.

You stay back six metres from the water's edge and you never enter the water.

Those two simple things never get attacked by a crocodile.

Although that is a very complex thing to comprehend for some people.

On this river, human and reptile have found a way to coexist.

Not that life is now easy for the continent's apex predator.

He is relentlessly hunted by the March Fly.

Not just here to hitchhike.

The fly seeks out divots in the crocs' armour plating.

Weakness found.

It bores its drill-like proboscis into the soft area of skin below.

A modified form of saliva prevents the croc's blood from clotting.

And then the fly mops up the blood with its fleshy mouthparts.

Filling to bursting point on its victim's rich cold blood.

The delicate three-layered eyelid is particularly susceptible to attack.

Nostrils are targeted too.

And from this perspective, the menacing croc is

reduced to no more than an involuntary blood donor.

Although he does have one pest control strategy.

Australia's all-natural fly repellent.

Not only a barrier to flies, but also a salve to soothe irritated bites.

At least for a moment.

It's not fatal, but it feels like torture.

And despite its ancient evolutionary line, the croc still has a distinct design fault.

Legs so short that there's an itch that can't be scratched.

While the croc is at war with its flies, the rest of the creatures who call

Australia's northern monsoon region home battle

the extreme viability of variations in climate.

Birds migrate to cope with the dramatic pulses of the wet and the dry.

Other creatures do not have this luxury.

Unable to move with the seasons, they must stay and face the elements.

On these flood plains in the far north of Arnhem Land, a creature has evolved a

unique coping mechanism to survive this seasonal change.

The children of Manangrida, whose playground spans these northern flood

plains, have discovered an extraordinary web of life beneath their feet.

In this one small area, they've helped scientists identify

an astonishing new species of tarantula, or didgeridoo.

This is the galloper.

Like most spiders, they have eight eyes and eight legs.

But what sets these tarantulas apart is their dashing red coat.

And fangs long enough to dig deep into flesh.

The flood plain is pockmarked by thousands of

spider burrows, a mega cluster of ambush hunters.

The female will spend hours waiting motionless for the perfect dinner guest.

She has laid silk out around her burrow entrance.

It's a carpet of tripwires.

Once in the tarantula's vices, like grip, there's no hope of escape.

She deals a final blow, injecting it with toxic venom.

The grasshopper is paralyzed.

Her last catch for the dry season, rumbles outside,

suggests her world is about to be inundated.

The monsoon has arrived.

Thunder heads reach over 12,000 meters high.

Electric charges begin to spark fire.

A thunderstorm producing the equivalent energy of an atomic bomb.

A flood makes its way towards the plain.

For a creature that lives underground, this can only spell danger.

But she is no ordinary tarantula.

She won't flee her burrow as the water table rises.

She has her own silvery life support system.

Her hairy coat traps air bubbles.

Keeping movement to a minimum, she can survive on these tiny air pockets.

Like an astronaut in space, she's created her own atmosphere.

Known only as the diving tarantula, their discovery is so

recent, they are yet to be officially named by science.

By the peak of the wet season, this area will be under half a meter of water.

And with nowhere to go, it's assumed she'll remain submerged for the next four months.

Scientists estimate there are 25,000 diving tarantulas on this flood plain.

The highest concentration of tarantulas anywhere in the world.

Most certainly, this is no place for an arachnophobe, or even a family holiday.

As the wet season departs the top end, it leaves behind a vivid savanna,

plumped by the rain.

Now it will be the dry season's turn to repaint the landscape.

But before the greens turn brown, they will be dressed in black.

And the

storm will be 200 kilometers south of Maningrida, the indigenous ranges of

central Arnhem Land are setting the ground alight.

They burn now It is time now to prevent

uncontrollable wildfires later in the season.

The crisp grass ignites quickly.

The flames move on, leaving the trees intact.

And as the smoke builds, the rangers know to look skyward.

They will almost always see a black kite overhead.

As the grass burns, a mass exodus of creatures is forced to flee the heat.

So the black kite, precision instrument that he is, can swoop on par-baked bugs.

But the kite doesn't feast alone for long.

As the smoke builds, so do the kites, arriving from kilometers around,

hundreds of them.

All are competing now for the spoils.

Squabbles break out, talons clash.

The traditional owners know what this bird might do next.

For thousands of years, dreaming stories have

been told of a bird that makes its own fires.

The clever firebird, or garaki.

The only creature, other than humans, known to harness fire for personal gain.

I don't like kites, but I do.

When I was a boy, I dreamed I wanted one.

I wanted to go for a big one.

I

was always laughing, but now I don't.

I don't know how to protect myself, I don't know what I am doing right now.

I'm just a little boy.

We've all witnessed building new fires to flush out

more insects, creating new hunting opportunities.

And despite being the world's most common raptor,

it is only Australia's kites which do this.

The rangers are left to deal with extra fires, while those guilty of fuelling the

flames fly free and are very likely to re-offend.

For tens of thousands of years, indigenous people have been telling the

stories of this ancient land and its creatures.

And yet there is so much about Australia's

wildlife that remains unknown to the world beyond.

About the indigenous people.

The intelligence.

The resilience.

And the perseverance of these unique and irreplaceable creatures.

Some are thriving.

While others are on the edge.

Australia may be an ancient land whose creatures have

grown over millennia from her rock and soil and flora.

But human change is shifting everything.

What this means for the future of Australia's animals is...