Desert Heart Wild Down Under

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Two-thirds of Australia is as dry as a bone.

Over 5 million square kilometres of rock, scrub, and sand.

When Europeans came looking for farmland in the centre,

just 150 years ago, they were dismayed by what they found.

They wrote it off as the "dead centre", rejected it as a good-for-nothing wasteland.

That couldn't be further from the truth.

The continent's dry heartland is like nothing else on the planet, and it's full of life.

But could the new Australians ever see this spectacular land and love it for what it really is?

Although the centre is hot, much of it doesn't look like desert at all.

The first European explorers were convinced they'd find pasture here.

They found swathes of tall grass - surely the answer to their prayers.

But spinifex is as tough as old boots.

It's the only grass that can grow in the poorest and driest soils.

The lack of native grazing animals should have tipped them off -

not even kangaroos can chew on this stuff.

But these grasslands were dotted with strange red mounds - a clue to what DID thrive here.

There ARE grazers - billions of them.

But the explorers couldn't see them.

Termites are the only animals that can stomach spinifex.

The grasslands cover a quarter of the continent,

so termites are one of the most powerful forces in Australia.

They've turned a virtually inedible grass into their bread and butter.

They have it all to themselves.

By chewing it up with spit and soil, termites can even turn spinifex into walls that harden like brick.

The result is a multi-storey complex that's both cool and secure, and not just for termites.

At any one time, the mound is crawling with spiders, centipedes, geckos and skinks.

The termites themselves are a living larder.

Most of the grassland's life-and-death struggles

are played out along the mound's humid passageways.

For the knob-tailed gecko, it's murder in the dark.

But the centipede is no walkover.

Each mound is a world within a world.

Termites eat grass, centipedes eat termites, geckos eat centipedes.

In the desert, termites make the world go round.

In the grasslands outside the mounds, there are others waiting to pounce.

Low-energy lizards have really struck it rich in this desert economy.

They are virtually drought-proof - they can survive on far less food and water than mammals or birds.

And so, there are millions of them.

Australia's desert wealth can be measured not in pasture,

but in the phenomenal variety of lizards per acre.

They have this unpredictable country licked.

Most lizards eat anything,

but this one is picky.

The thorny devil only eats little black ants - 1,000 a day - IF he can get into the groove.

It's cleverer than it looks.

Ants know the whiff of a dead comrade, so the devil never lets them smell its breath.

It lifts its head to puff away the tell-tale formic acid fumes.

The ants never catch on.

The first Europeans thought all these animals were useless.

And when they didn't find rich grazing land, they just saw emptiness - the never-never.

So it was a big surprise when they found people making a living here.

Aboriginal people have survived in the centre for over 40,000 years.

They moved across the land, tapping into many different water sources, and living off bush tucker.

They understood how to make the desert work for them.

They also used fire, not just for cooking and warmth, but to manage the land.

They still use fire-stick farming today to burn off the prickly spinifex

and encourage edible plants to grow in its place.

It's a controlled version of the wildfires that would have swept through the outback,

even before these people arrived.

Most of the plants in the bush are dry and naturally packed with oils.

They ignite readily, but they don't always die.

And their seeds often survive a blaze.

The scorched earth is a kick-start for new growth.

Bush tomatoes, yams and bush berries flourish.

Strange as it may seem, many plants have evolved to live with fire, and so has the wildlife.

The mala is a small desert marsupial that cannot breed

without the succulent shoots that germinate after fire.

Bilbies also benefit from fire-stick farming.

They look like down-under Bugs Bunnies, but they are marsupials too.

They eat more or less anything, but after a blaze, the poor desert soil is fertilised by the ash.

So there's a greater variety of plants and insects to sample.

Like the mala, they feed after dark to avoid dehydration.

It's wickedly hot during the day, so some kind of shelter is vital.

They have powerful front legs and claws to help with that.

Two metres down is an air-conditioned retreat for the whole family.

And it is also the safest place to be during a grass fire.

In good years, after a burn, they can have four litters on the trot.

So they can breed like rabbits.

To survive in the outback, you need to understand how it ticks,

something the Aboriginal people had learned from the life around them.

To them, this landscape is steeped in meaning.

Their journeys across the centre follow paths of memory and understanding,

which often meet at sacred places, like Kata Tjuta and Uluru.

To us, it's a photo opportunity.

To them, it's a timeless place that describes the way they see the world.

Patterns of erosion on Uluru's surface tell the story

of how the people are connected to their ancestors and to the land.

They are intimate with it.

But for newcomers, the desert heart couldn't be more alien.

Frustrated Europeans battled to find a route across the continent.

Having travelled thousands of kilometres over the flattest country in the world, they were disheartened

to find a chain of mountains blocking their way.

The McDonnell Ranges were once Himalayan-sized,

but Australia is so old, they have crumbled and rusted into a geriatric spine.

Even so, it was a challenge to find a way through.

Unexpectedly, their search took them from desert to an inner sanctum of natural wonders.

65 million years ago, Australia was covered in luxuriant forests, like these.

This valley of red cabbage palms is the last of its kind.

They were cradled here as the climate dried up,

saved from drying out because the porous rocks around them hold water like a sponge.

Some of the trickle-fed pools never dry out.

That's heaven in a place where it might not rain for years.

Here, in the heart of the desert, explorers were amazed to find freshwater fish.

The billabongs in the ranges are so isolated that some fish are found only in particular pools.

This must have been a sight for sore eyes.

Because of this permanent water, there are more bird species in Australia's deserts

than in all of Britain.

It's a particular life-saver for birds on a dry diet of seeds,

such as budgies and zebra finches, who need frequent drinks.

The finches pump the water up with their tongues.

They need to be quick.

They are forced to to play cat and mouse with local falcons.

But it's the spectator that gets lucky.

Life is a gamble in the desert, and there are only a few deep, shady gorges that never dry out.

That's where black-footed rock wallabies hole up in the crevices and caves.

A sun-soaked ledge takes away the night chill.

Usually, they're not around in the day,

but this is the breeding season, and life is getting a bit frenetic.

The male is trying to winkle himself in behind the female.

But she's determined to keep her back to the wall.

To reach all the females, he needs mountain-goat precision, and wallaby spring-loading.

They'd like to stay glued to the rock face, but most of their food is on the gully floor.

Rock wallabies are not much bigger than a cat.

Packs of dingoes work these gorges, so they need to watch out.

As the day stokes up, they do the sensible thing and find some shade.

In most other deserts of the world, rainfall follows a pattern, however scarce it might be.

In Australia, it is totally and utterly erratic.

The rain is usually too light to make a difference, but the mountains channel whatever does fall.

Rivulets become creeks and then rivers. This is how a little goes a long way.

The Fink River has been cutting its course out of the Central Ranges for nearly 300 million years.

It's thought to be one of the oldest rivers on Earth.

It doesn't go to the sea, but heads further into the desert.

Over a 700km route, it transforms the dry lands beyond the mountains.

Even as a ribbon of sand, it's beaded with precious waterholes.

And long after water has vanished from the surface,

an avenue of trees can tap into water hidden deep into the sand.

Red-tailed black cockatoos are never far from the Fink.

They flock along it, to wherever the food and water happen to be.

The large trees are a real draw.

It's in their shade that the cockatoos spend the hot afternoons socialising.

Red river gums offer multi-storey housing,

with made-to-measure nest holes.

These cockatoos are large parrots, so they need something roomy.

It'll be a tight squeeze once mum is in there too.

These intelligent birds can live for over 50 years, and they spend a whole year raising a single chick.

It has a lot to learn.

The outback is not a predictable place.

In a long run of difficult years, cockatoos must fall back on past experience to find enough to eat.

Aboriginal people also had to be resourceful, and they never stay too long in one place.

The Fink was a natural highway, so not surprisingly, it also opened up the centre to newcomers.

They arrived on imported camels and muscled in around the reliable water holes.

The Aborigines fought the land grab.

There were ugly conflicts.

By the late 1800s, even the poorest range-land had been settled.

But many cattle stations went bust after a few dry years.

It's easy to get caught out.

The centre can look more promising than it is.

Mulga country doesn't even seem like desert.

It's a dense woodland of acacias, bloodwoods and ghost gums, rooted in the outwash of the Central Ranges.

Most woody shrubs are thirsty and demanding, but these tough plants have flourished,

despite the poor, dry soils, and despite unwelcome invaders.

In the 1880s, camel trains were the only way to cross the desert,

but once roads had been built, the camels were abandoned.

With no natural predators, they have made themselves at home.

Australia is now the only country where one-humped camels live naturally in the wild.

In the breeding season, males do their best to pull as many females as they can.

The inflatable sac lining the roof of their mouths could only be a camel turn-on.

But mostly, this display is for the males.

The biggest bull starts to throw his weight around.

Things can get really heavy.

This upstart gets well and truly bounced.

Over half-a-million camels roam the centre now.

They are no longer a curiosity.

They are serious pests.

Despite their overwhelming presence,

it's the little guys who run the place.

Every morning, a huge ground-level operation takes place.

Units of meat ants fan out to find overnight carnage.

They'll butcher this dead grasshopper,

and then carry the body parts back to their bunker.

Meat ants outnumber everything at floor level.

All other invertebrates are dead meat.

Taken below ground, these bodies are an extra dose of fertility in the soil.

Ants give mulga trees the boost they need to grow in the desert.

Deep in shade is a nest of bulldog ants.

There are over 1,000 different species of ants in Australia, and these are the ankle biters.

Each one is 4cm of aggression - a creature of the underworld.

But they aren't out for themselves.

Caring and sharing works best in the desert.

Hunters bring back insects, even reptiles, which feed everyone inside.

They've dug shafts two metres underground.

The queen and her larvae are coddled in the deepest, coolest and best-protected chambers.

Teamwork is the ultimate buffer against extreme heat and drought.

The queen produces a constant supply of larvae.

With squads of carers, fortress builders and food gatherers,

these colonies are virtually immortal.

Beyond the influence of the ranges and the Fink River,

this driest of continents presents the greatest challenge -

the largest area of parallel sand-dunes in the world.

The Simpson Desert would cover most of Britain.

The early explorers miscalculated much of Australia's desert,

but there is no mistaking the Simpson.

The towering ridges were piled up 18,000 years ago by storm-force prevailing winds.

It's still windy today.

Aboriginal people avoided it, and when the first European reached it,

Charles Sturt thought he stood at the gates of hell.

Europeans didn't cross it until just over 60 years ago.

In 1939, a scientific expedition rode into the inferno.

It was part field trip, part adventure -

the white man's stamp on the last area of Australia to be explored.

A final frontier, where it hits 50 degrees centigrade in summer, and where sandstorms can blow for days.

The expedition never saw how animals cope in this fan oven, because most of them stay well-hidden.

The main survival trick is to only come out at night.

There are a surprising number of animals in the desert hardcore.

One of the toughest is the mulgara.

It doesn't even need to drink.

Insects are 80% water, so it gets all the food and liquid it needs from its nocturnal hunts.

Nor can they be fussy about what they eat.

Mulgara will switch between anything -

birds, lizards, insects, spiders, even other mammals.

They store fat in their stubby tails to see them through lean times.

No other country has so many feisty little desert carnivores.

Even when a male makes a romantic advance, it's a ferocious affair that could last eight hours.

Although they mate every year, many litters die.

Sometimes, there's just not enough food.

But mulgara can live for over six years.

A few survive even the longest droughts, so at least some babies are likely to make it through.

The Simpson Desert is hot, but it's not hell, even for little devils.

Under the sand dunes, it's cooler, and the temperature stays stable,

a good place for thorny-devil eggs to incubate.

Although the egg chamber is a bit gritty, it's safe, so they can take their time hatching out.

It's just a halfway house.

Once they've rested and their spikes have hardened up, the babies will dig their way out.

Tunnelling up through half a metre of sand when you're thumb-sized must seem like the Great Escape.

First, they get their bearings.

They could easily overheat, so they look for shade.

Running on instinct seems to work in the end.

And they find their first meal of ants.

The Simpson Desert might seem like a life sentence to humans,

but not to the free, roaming symbol of the outback.

Red kangaroos are Australia's biggest native animal, standing taller than a man.

But they live on sparse grasses and herbs.

Five-metre bounds are an efficient way to cover lots of ground, in the search for scattered food and water.

Many roos die during severe droughts.

But they get numbers back up during good times by becoming permanent breeding machines.

At any one time, a female can have an embryo on hold inside her,

a joey suckling on one type of milk in her pouch,

and a young at foot, drinking a different type of milk from a separate nipple.

With all this going on, the males are in a constant state of sexual tension.

The only lose their drive in the very driest and hottest years when their testes quite literally dry up.

This way, everyone saves energy.

Even though they're big, kangaroos don't need liquid every day.

But where do they find a drink in a sun-baked land with little or no surface water?

On the western edge of the Simpson Desert, there's an oasis.

It's a series of natural springs that have forced up from underground.

Aboriginal people knew where to find them, and which springs flowed, even in the worst droughts.

Australia's such a vast continent, that early explorers were convinced

that they would find an inland body of water.

When they first asked about the existence of these springs, the aboriginal people lied.

This knowledge was gold dust.

Each pool is like a desert spa, complete with exclusive clients.

The hot-water vents stir up a cocktail of algae and other food, where some of the fish feed.

These aren't called Dalhousie hardy-heads for nothing.

They're swimming in water that's halfway to boiling point.

The Dalhousie Springs, as they are now known,

leak out from a much larger and more extraordinary natural wonder -

one of the biggest underground reservoirs anywhere -

the Great Artesian Basin.

Much of this water fell as heavy rain long ago out east.

It has taken 2 million years to slowly seep down and through the porous underlying rock

to the centre.

It would be many decades

before the colonists learned to pump this water up for their sheep and cattle stations.

In the very early days, they pinned their hopes on rumours of an inland sea.

This is what they found.

From a distance, it looks like a snowfield, except that here, an ice cream would melt in seconds.

It's a salt lake.

Lake Eyre covers 9,000 square kilometres, and lies 15 metres below sea level.

It's the very sump of Australia.

A sea all right, but one of mud, covered with a blinding, heat-thickened salt crust.

In 1840, when Edward John Eyre discovered it,

he stared in horror at "one vast, low and dreary waste".

Although the lake was named after him, his hopes of finding water were crushed.

He called it Australia's Dead Heart, and the name stuck.

Eyre, like most of the Europeans who came after him, never got to grips with Australia's desert centre.

They had never experienced a place so random, so unforgiving.

A place where it never rains, but it pours.

You may have to wait over 10 years to see this.

And every 30 years or so, it rains so hard, even Noah would be impressed.

Thousands of square kilometres of desert are awash.

But as these epic floods drain away, something truly remarkable happens.

None of this water will ever reach the sea.

It flows inwards to the country's lowest point - Lake Eyre.

Edward Eyre had been in the right place at the wrong time,

and missed one of Australia's most astonishing spectacles.

It is not known whether birds on the coast - 1,500 kilometres away - can smell the water,

or whether they sense a change in the atmosphere,

but they arrive from all over Australia, and in their thousands.

Pelicans head for the islands, where their nests will be safe from goannas and dingoes.

By the time the last spaces are being filled, some chicks will have hatched already.

But how do they know to breed here?

If this desert sea only forms every three decades, how do they know what it has to offer?

Pelicans are long-lived, and it is now believed that the wise old birds remember where to go.

And they aren't the only ones to keep coming back.

These waters are stuffed beyond imagination with fish, shrimps, mussels and yabbies.

A population explosion, triggered by the floods.

And it is all within easy reach.

Pelicans operate like a fleet of trawlers, scooping their netted beaks through shoals of fish.

Then, when their crops are full, they return to offload the catch back at the nest.

This isn't just a family gathering, it's a pelican pick-up joint.

Birds from different parts of Australia get together,

and in this way, pelicans keep their genes well-mixed.

There are around 50,000 pairs in this colony.

Some chicks are nearly as large as their parents.

In their frenzy to eat, the big ones almost suffocate down their parents' gullets.

They have to be shaken out.

Pelicans will spend the best part of a year here, breeding to the bitter end.

The chicks that hatch last may not have fledged by the time the fish run out.

Lake Eyre will evaporate into mere memory.

Australia's desert heartland is dominated by this breathtaking cycle of drought and flood.

It doesn't follow any rules.

Which is why for over a century, most new settlers turned their backs on it.

Only very recently did the centre become a place to visit.

People have come to love its stark beauty and intriguing detail.

With understanding has come respect, both for its nature and its people.

It's now treasured as the very essence of Australia.

The much-maligned centre has finally been taken to heart.

Next week, Wild Down Under takes to the sea,

from the dazzling tropics to a wild Southern Ocean.

Just like the land, Australia's seas are extraordinary and different.

This is a journey around Australia's dramatic coastline, revealing the most spectacular seas on the planet.