BBC Wild Down Under

Modern Australia... lt seems a familiar sort of place...

...but step outside these cities and you could almost be on another planet.

Because Australia is the strangest continent on earth.

lts wildlife is so weird

that at first some people thought the animals were a hoax...

...or the work of the devil.

lt's a paradox, a place of extremes -

its centre a burning desert,

but also with rugged mountains, covered in deep winter snow.

lt has endless horizons of magical, time worn landscapes...

...and in them an amazing variety of wildlife...

...more species of animals than Europe and North America combined...

...almost all of them unique - they live nowhere else on earth.

lt's a place that likes to do things differently.

And somehow, this remarkable mix of wildlife

manages to survive on the harshest, driest inhabited continent on earth.

So how did Australia come to be so special?

To answer that, you need to travel back in time to

when this was a very different kind of place, covered in trees.

1 00 million years ago,

massive forces shattered the super-continent of Gondwana

and eventually a giant fragment floated off northwards,

with a unique cargo of wildlife.

Australia was born.

This was an extraordinary world,

lush, green and dripping with life.

Today, there are still a few places in Australia

where you can get a feel for that past.

These are the rainforests of Tasmania.

They're ancient, mysterious places

and some of Australia's oddest animals live here, like the Tasmanian devil.

They're scavengers,

sort of antipodean hyaenas,

and they use their powerful jaws to crush up every bit of a carcass.

You may get a dozen or so around a dead Wallaby...

...and they find it hard to share, let alone be sociable.

With such lethal teeth, manners like these can be very dangerous.

Screaming at each other is safer,

but better still is bum barging your neighbour

with a few powerful blows from behind.

This competitive spirit starts early in life.

Devils are marsupials -

their babies develop inside a pouch -

and while this mother is jostling for a meal

the young are tucked away inside doing much the same thing.

Mothers produce about 20 embryos

and they have to fight for just six teats,

Competition is fierce and even the ones

that survive still have to fight for a drink.

Only three or four usually make it out of the pouch.

By then the competitive spirit is well established -

and will stay with them for the rest of their lives.

Dense forests are not just confined to Tasmania -

they spread right up the eastern coast of the continent because,

soon after Australia became an island,

its eastern side was buckled into mountains.

These trap rain, blowing in from the ocean.

So their lower slopes are covered in thick forest.

Higher up, there are rugged peaks.

And in the south, in winter, the rain falls as snow.

These are the Australian Alps, covered in snow for months of the year.

ln places it drifts up to 30 metres deep.

lt's not something you'd expect to see in a land,

which is mostly dusty and hot,

but this weather can be ferocious and unpredictable...

Sometimes there are blizzards.

But even here, there are marsupials determined to make a living.

This is a wombat, doubling up as a snowplough in an attempt to find food.

Wombats are world-class diggers,

and they use their strong front legs and snout to bulldoze through the snow,

in search of grass beneath.

They're normally nocturnal,

but now it's far too cold to come out at night,

so they forage during the day, even in the worst of the weather.

lt's a tough place

but there are other marsupials up here as well - dainty little wallabies.

Surprisingly, both the wallaby

and the wombat have young families in these conditions,

in the depths of winter.

But there's a good reason for this -

these joeys will emerge in spring,

just in time to feed on the new green shoots.

Meantime, a centrally heated pouch is the warmest place to be.

Even the world's weirdest mammal, the platypus,

makes a living in the icy waters of these mountains.

Uniquely Australian, it has a duck's bill,

an otter's tail and webbed feet with claws.

Males have poisonous spurs and females lay eggs, like birds -

so it's hardly surprising that early reports of them were treated as hoaxes.

lt's actually a monotreme, a typically Australian group of mammals.

That weird looking bill is highly specialised,

with tiny sensors

to detect the minute electrical signals from the muscles of its prey.

So sophisticated, the platypus can swim with its eyes and ears closed.

By swinging its head from side to side,

it builds up a radar-like map of the stream,

pinpointing the shrimp and worms it likes to eat.

lt's a very adaptable animal, making its home in forest streams like these...

all the way up the east coast of Australia...

...from the snowy mountains of the south,

right up to these tropical rainforests in the north.

Like the Tasmanian forests,

these are also ancient and have been here since before Australia was born.

The land they cover today is relatively small,

just one thousandth of the continent,

but they have just about the richest mixture of wildlife

of any of Australia's environments.

lt's here, of all places,

you can see what a truly strange place Australia is -

here more than anywhere, you see how its original cargo of wildlife

has evolved into such a variety of unique species.

lmprobable giants, like this flightless Cassowary.

And marsupials, in every shape and form, including the possums.

One of the most striking is the striped possum,

which scampers over tree trunks looking for grubs and nectar.

There is no better source of nectar than the bumpy satin ash -

covered in thousands of tiny blossoms growing straight from the trunk.

The possum gets a sticky meal

and it also picks up pollen on its fur, transferring it from tree to tree.

There are 26 species of possum in Australia

and almost half of them live in these rainforests.

Some have found ingenious ways to move around.

This is a sugar glider...

Flying through the air - or perhaps just falling with style -

they use their own built in sky diving suits,

to glide from tree to tree for up to fifty metres.

They can steer, even change direction by ninety degrees,

by adjusting their flaps of skin, and using their tails as a rudder.

When it's time to land,

they just lower their flaps and put out their landing gear.

Although touchdown could be better!

But why did some possums evolve to glide?

Soon after Australia became an island, its climate started to dry out.

The thick, tangled forest that had covered most of Australia

for so long began to thin out into open woodland.

lt was a change that stamped the character of the Australian bush we know today.

The lush rainforest was replaced by Eucalpts, or gum trees.

With trees now further apart,

some possums evolved to glide across the gaps.

And there was now space for other types of travel too.

Kangaroos evolved in woodlands just like these.

You need room to bounce around like this,

a uniquely Australian solution to budget travel.

At certain speeds,

a hopping kangaroo is more efficient than any horse or antelope.

They live in family groups called mobs,

and females can be impressive breeding machines -

there are over fifty million kangaroos in Australia,

more than twice the human population.

Having such a successful design is all very well,

but you need to know how to use it.

Just three days out of the pouch,

this Joey has more than just a spring in his step.

Learning to get about on two supercharged pogo sticks is no mean feat.

That was exhausting - time for a nap.

But as you grow older, fitting those legs inside isn't easy

and within two months he'll be out of the pouch for good.

Up in the gum trees,

there's another marsupial with a less energetic approach to life...

lt has the laid back Aussie love for leisure.

This koala is putting his back into taking it easy.

Koalas eat gum leaves, which are full of toxins and hard to digest.

To survive on a diet like this they've turned napping into a national sport.

Of course, it looks like dozing,

but these guys are working really hard to digest their meal.

But at one time of the year this all changes...

lt's spring and the males want to mate.

To kick-start the season, they begin by calling.

But if your date is almost comatose, that may not be enough.

For some of the older males, this is already too much like hard work.

They can't keep the mood going for long.

For those who can gather enough energy, the chase is on.

But this female, with a baby on her back, is not ready to mate...

For a koala, this is really getting a move on.

But males can be very determined.

Gentlemanly courtship is not his style.

Nor is the female willing to give in.

ln fact his only skill seems to be the ability to turn a drama into a crisis...

The baby is now in serious danger

and in the scramble gets separated from its mother.

But it gets even worse.

ln the confusion the youngster ends up dangling from the bottom of the male.

This farce could easily turn into tragedy.

The male has bungled the whole episode.

lt's time to exit,

but as he slams into reverse, he takes the baby with him.

Escape at last, but the baby isn't out of danger yet.

Young koalas depend on their mothers until a year old...

and this one is too small to survive on his own.

Encouraged by her calls, though, he manages to sprint the last few metres -

back into her arms.

Now he's safe.

Raising babies, with or without rampaging males in the neighbourhood,

is not easy in these Eucalypt woodlands.

They're tough places, dusty and dry, without a lot of food.

...especially with mouths like these to feed.

This is a kookaburra

and these chicks are demanding customers.

They want round the clock room service.

lt's a problem for parents to provide this on their own