DAVID ATTENBOROUGH: At the southern
tip of the Australian continent
lies a remote island.
An immense wilderness...
..divided by mountains.
It's a world of ancient forests...
..of pristine rivers...
..and a coastline...
..that's both wild and beautiful.
Its animal inhabitants are
as extraordinary
as they are bizarre.
This is a land of black devils...
..and white wallabies...
..where lights dance
in the southern sky
and trees tower to 100 metres.
This is Tasmania,
the weird and wonderful isle
at the bottom of the world.
Tasmania is full of surprises.
Australia, yes, but with a twist.
It was once connected to
the dry Australian mainland.
Today, along with
its plants and animals,
it's physically cut off.
Though it lies just to the south,
Tasmania is a world apart.
Its isolation and cooler climate
has created a sanctuary
unlike any other part of Australia.
And a strong seasonal cycle makes
life here very different indeed.
Winter means a struggle for survival.
In Tasmania's mountains
there are meagre pickings on offer.
This is the last landfall
heading south before Antarctica.
Cold air from further south brings
snowfall and freezing temperatures
throughout these winter months.
Many animals, like this female
wombat, are Australian species.
But their habits and lifestyles
are most definitely Tasmanian.
Mainland wombats
are largely nocturnal
but here she feeds
at any time of the day,
kept warm by her thicker coat of fur.
She must take every opportunity
to find food.
Winter is felt right across
this island wilderness.
Even lower down
in Tasmania's forests,
temperatures can fall
below freezing.
The first Europeans
to explore these forests
claimed they heard devils
screaming in the night.
(SINISTER SCREAMS)
And so Tasmania's
most famous animal got its name.
The Tasmanian Devil.
Primarily scavengers,
they can smell a carcass
from a kilometre away.
And relative to body-size,
they have the most powerful bite
in the natural world.
They can easily crunch through bone.
Devils once lived
throughout Australia,
but vanished as the continent
dried out and humans arrived.
Today, this is their last stronghold.
Like most Australian mammals,
they're marsupials.
While they may appear dog-like,
devils are more closely related
to kangaroos than canines
and, being marsupial, they rear
their young in a pouch.
A few weeks ago this female
gave birth to 40 young...
..each the size of a grain of rice.
Inside her pouch
she has just four teats,
so only four young will survive.
A devil's race for survival
begins early.
It's a tough start,
but this mum will dedicate
most of her year
to looking after
the four babies who survive.
She overcame extraordinary odds
to reach adulthood.
Now it's her turn
to raise the next generation.
Marsupials like the devils live here
because Tasmania was once connected
to mainland Australia.
The island and its inhabitants
became isolated some 12,000 years ago
when sea levels rose
following the last ice age.
But Tasmania is a window
on a far more ancient past.
Some of these forests
have barely changed
since dinosaurs walked the earth,
when the southern continents
were a single landmass
called Gondwana.
There is still a creature here
whose ancestors roamed
that ancient supercontinent.
It lives in Tasmania's rivers,
and is one of the island's
longest-lived survivors.
The Tasmanian giant lobster.
Weighing up to five kilos
and a metre long
they're the biggest
freshwater invertebrates
on our planet,
taking some 40 years
to reach full size.
Tasmania's isolation, together
with the lack of sizeable predators,
may be one reason
why they grow so massive.
But they're not entirely free
from threat.
Tasmanian platypuses are enormous.
As much as three times heavier
than their mainland counterparts.
It's an adaptation
to the cooler southern climate.
This male is after tiny invertebrates
found on the riverbed,
including young lobsters.
And to stay warm in winter,
he must find a lot.
He needs to keep moving.
With no large predators
to worry them,
platypuses here get about
in an unusual way.
Only in Tasmania
does the Platypus walk
between rivers in broad daylight.
Out of water it's easy to see why
the platypus was once dismissed
as a fraud, the work of a hoaxer.
But down here he is in his element.
His strange assemblage of body parts
soon begins to make sense.
Webbed feet help him move...
..while his otter-like fur
keeps him warm.
His beaver-like tail stores fat.
But the platypus is best known
for its duck-like bill...
..which it uses to find food.
Underwater, he's completely blind.
Not ideal for avoiding rocks.
But some 40,000 receptors in the bill
detect electrical signals
given off by the muscles
of prey animals.
With the need to eat a lot
just to keep warm,
a platypus can stay on the hunt
for some 12 hours a day.
Though also found on the mainland,
Tasmania's platypuses are by far
the biggest and boldest.
They, like others, are adapted
to the island's isolation
and cooler climate.
Lying 240km south of Australia...
..Tasmania is surrounded
by a vast expanse of open ocean.
To the west, the next landfall
is South America...
..thousands of kilometres away.
To the south lies
the great Antarctic continent.
And as winter comes to an end,
new arrivals come ashore to breed.
Penguins.
Hidden among the rocks,
this female has two
newly-hatched chicks...
..but nothing to feed them.
Her partner left some 14 hours ago
and is yet to return.
He's out fishing.
But, quite unlike any other penguin,
he must wait for nightfall
to leave the water.
Gulls and birds of prey
patrol the coast by day.
It's only safe to return
after sunset.
That is because
these are little penguins.
At only 30 centimetres tall,
they're the smallest penguins
in the world.
And with nests
several hundred metres inland...
..the only safe way to get there
is to make a dash in the darkness.
There's safety in numbers.
(PENGUINS CALL)
With hundreds of nests
in the colony,
the night soon fills
with the calls of returning adults...
..the sound of early spring
on Tasmania's coast.
(PENGUINS CALL)
This will be a welcome meal
for the newly-hatched chicks.
The little penguins' presence
is a reminder of
Antarctica's proximity.
But, while early spring
brings them ashore to breed,
it also brings
wild and unpredictable weather.
Prevailing winds carry most
of the bad weather from the West...
(THUNDER RUMBLES)
..and Tasmania's mountains
cause much of the rain
to fall on the western half
of the island.
(THUNDER CRASHES)
The result divides Tasmania in two,
with a wet western side
and a dry eastern side.
Some western areas are among
the wettest in all of Australia.
It rains here nearly every day.
And all the water supports
a surprising spectacle.
Caught in a bizarre trap,
these insects are doomed.
How they got stuck only
becomes apparent as night falls.
These strange lights belong
to the larvae of a type of gnat.
The light is formed
by a chemical reaction
in the larva's abdomen,
and can be turned on and off at will.
The sticky threads hang from
its silk and mucus-laden nest.
Insects drawn to the light
are ensnared, then devoured.
Each glow worm's thread is made up
almost entirely of water,
so the high rainfall
in Tasmania's wet west
provides ideal conditions.
And the rain that supports
these tiny glow-worms
also sustains one of the largest
organisms on the planet...
..mountain ash.
They are a type of eucalyptus...
..fast-growing trees that evolved
on the dry Australian mainland.
In Tasmania they become giants.
Strangely, for trees
living in a wet forest,
they need fire to reproduce.
The mountain ash
stores its seeds in small pods...
..which are released
as the pods burn.
Beneath the ash, the seeds live on,
quickly germinating without
competition from other plants.
This makes sense in a dry habitat
with regular fire...
..but not in Tasmania's wet forests.
Young mountain ash can grow
at a rate of several metres a year.
All that holds them back is
the next fire or a lack of water...
..and that is the secret
behind their staggering height.
In Tasmania's damp west,
fire is so infrequent
these trees keep growing
for centuries.
Those standing in this valley
all germinated
following the same devastating fire
400 years ago.
Today they reach almost
100 metres into the sky.
They may have evolved
on the dry Australian mainland,
but it's Tasmania's wet forests
that have turned mountain ash trees
into the tallest flowering plants
on Earth.
The moisture-laden air
that blows in from Tasmania's west
brings several metres
of rainfall each year.
Although it can rain most days,
winter and spring
are the wettest times
and seasonal waterfalls
burst into life.
All who live here must adapt
to the regular downpours
and cooler temperatures.
And like so many of
Tasmania's species,
their adaptations set them apart.
It may not look like it,
but this is the closest
living relative of the platypus.
The echidna, Australia's most
widespread native mammal.
But while mainland echidna
are all spines,
this Tasmanian one
is mostly covered in hair
to help keep him warm.
The milder spring months mean
an abundance of his favourite food -
ants.
But when you're this hairy,
your food gets stuck everywhere,
which is a pain
when it can bite back.
Time to move on.
As spring turns to summer,
Tasmania's inhabitants
get some relief
from the wild and cool weather.
It's now that the young devils
are ready to leave the den.
They've been out
of their mother's pouch for a while
but have remained safely hidden away.
Fully weaned, this is the start
of their independence.
This young female will have to learn
to survive and find food
all by herself.
What's more, she and her sibling
are much smaller than an adult.
They could easily be killed.
This will be her way out of danger.
Heavier adults can't climb,
so there are some benefits
to being small.
Over the next few months,
she'll also find
much of the food she needs
up here in the treetops.
But grubs and birds' eggs alone
won't be enough
to sustain her as she grows.
(GROWLS AND SHRIEKS)
If she's to make it to adulthood,
she needs to find
more substantial meals.
And that brings her
into direct competition
with dangerous
and more powerful adult devils.
The scent and sound
of crunching bones draw her in.
But she needs to be careful.
Less than half
of all newly-weaned youngsters
make it to adulthood.
(SCREECHES)
If she is to survive,
she needs to earn her place.
There's no telling
how this adult might react.
Confronting a stranger at a carcass
is a gamble...
..but one she needs to take.
(SCREECHES AND GROWLS)
Spurred on by hunger,
she seems to have the upper hand.
It looks as though
her gamble has paid off.
But her competitor
won't let the carcass go that easily.
The adult could kill her
with a single bite.
But that's not
how devil society works.
Despite living
most of their lives alone,
devils can and do share.
They defend only
the amount of meat they can eat
rather than the whole carcass.
The pecking order has less to do
with size and strength
and more to do
with whoever wants it most.
As this youngster is learning,
it's all about
who can shout the loudest.
Devils may have a fearsome reputation
but the reality is quite different.
Summer brings warmer temperatures
across Tasmania.
While in the west
it still rains frequently...
..summer is most apparent in
the dry eastern half of the island.
The driest areas of Tasmania
receive 80% less rainfall
than the wettest.
Here the landscape is
more reminiscent
of parts of the Australian mainland.
For marsupials
that graze the open grasslands,
there's a bounty of fresh shoots
in these warm summer months.
And although life here may appear
more typically Australian,
the effect of Tasmania's isolation
is felt just as strongly
in this dry half of the island.
It's given this group of wallabies
something of a Tasmanian twist.
They've turned white.
About 100 of them live
within this population.
They're so poorly camouflaged
that anywhere else
they'd be easily killed.
On Tasmania however,
there aren't any predators
big enough to kill a wallaby,
so many live full adult lives.
And without the normal controls,
their numbers are growing.
But although this may appear
a predator-free paradise,
there are killers here.
One of Tasmania's deadliest animals
lives in these dry forests.
It's a species of ant
known as the jack jumper.
Jack jumpers evolved on
the ancient Gondwanan supercontinent.
Workers hunt alone...
..a very primitive behaviour
among ants,
which are mainly social.
And instead of using scent to hunt,
they rely on acute vision.
They sting their victims to death
with a venom that can kill humans...
..making these
one of the deadliest animals
in all of Australia.
Jack jumper ants are
particularly abundant
in this dry half of Tasmania.
Their nests are small mounds
within which their larvae are raised.
Workers cover the nest
with dark materials
to help absorb warmth
in the cooler southern climate.
In midsummer however,
temperatures soar...
..and the nest risks overheating.
But jack jumpers have
a surprising way
of coping with the intense sunlight.
On hotter days,
they switch building materials.
Now the workers cover the nest
in white stones.
These reflect the sun's energy,
keeping the young cool inside.
It's an inventive solution
to Tasmania's changing seasons.
The dry eastern forests can be
a challenging place
in the heat of midsummer.
But one of Tasmania's
few marsupial predators
avoids the worst of this heat
by hunting at night.
It's the eastern quoll,
a close relative
of the Tasmanian devil.
They're very rare, but summer sees
an increase in numbers
as juveniles leave the den.
Quolls are solitary hunters...
..and in summer are drawn
to these dry pasture lands.
There's a rich bounty of moths
and grubs at this time of year.
(GROWLS)
But, with lots of youngsters around,
competition can be intense.
(GROWLS)
It's every quoll for itself.
Like Tasmanian devils,
eastern quolls were once found
on the Australian mainland.
Today, this dry
eastern half of the island
is their last refuge.
And, with an abundance
of summer insects,
they have every chance of thriving.
Summer is almost over...
..and as autumn arrives,
the stage is set
for a bizarre ritual.
Familiar screams fill the forest.
(SHRIEKS AND GROWLS)
It may not look like it
but these devils
are becoming amorous.
An eligible male clings on
as a female guides him
back to the den.
Female devils are
receptive three times
over a short period
during the breeding season.
To ensure the fittest offspring,
she'll try to mate
with as many big males as she can.
And to increase
his chances of fatherhood,
he must keep her in here
for as long as possible.
Inside the den, he moves her around
in an effort to mate.
To protect her from his biting grip,
the skin around her neck has
thickened over the last few weeks.
Though it may appear aggressive,
this is part of a bizarre
and complicated breeding system.
They'll remain in here,
mating regularly, for several days.
In spite of that fearsome scream,
there is a sensitive side
to these much-maligned creatures.
Far from devilish, they are simply
very determined survivors.
The devil mating season
marks autumn's arrival.
Each evening,
flocks of Cape Barren geese
return to their roost.
Their silhouettes in the sunset,
a sign that the year is ending.
Back on the coast,
the longer nights bring with them
a stunning spectacle...
..the southern lights,
a reminder that the next stop
from here is Antarctica.
For Tasmania's little penguins,
the breeding season has finished.
Only adults remain at the colony.
They've spent the last few weeks
fattening up at sea,
almost doubling their weight.
The efforts of raising chicks
have left them in need
of a new set of feathers.
Little penguins go through what's
known as 'catastrophic moult'...
..shedding some 10,000 feathers
all at once.
Because their feathers keep
them warm and waterproof,
they can't return to sea
until they've grown new ones.
For three long weeks
they're stuck on dry land,
unable to feed.
It's a long wait
for a little penguin.
The year is almost over.
And, high in the mountains,
there's time for one last surprise.
These are southern beech trees...
..unique to Tasmania.
Their changing colour makes
for an autumn
unlike anywhere else in Australia.
These are the only trees
on the continent
to drop their leaves
during the cooler months.
The southern beech trees'
closest living relatives
are found
thousands of kilometres away
in South America.
This rare splash of autumnal colour
lasts just a few weeks
as, across the whole of Tasmania,
temperatures begin to drop.
June marks the start
of the winter season
and, for the devils,
the beginning of new life.
With young already inside her pouch,
she will provide milk for them
through the harshest months.
Her life and theirs,
tied to Tasmania's seasonal cycle.
Just 12,000 years ago,
Tasmania separated
from its mainland parent.
The island is young, yet rich in life
and with a long and ancient past.
Now Tasmania,
and the animals it supports,
are on a different course
to the rest of Australia.
It is, as a result, home to a cast
as weird as they are wonderful.
Indeed, there's nowhere on earth
quite like Tasmania.