All language subtitles for C426B8538FFA6CE472ACD275C4A1F63E_eng

Where the coastal
mountains meet the Pacific

lies the Alexander Archipelago,

a remote island chain,

running for almost 500 kilometres
along the Alaskan panhandle.

Defended by ramparts
of rock and ice to the east

with 5,000 kilometres
of ocean to the west

this frozen frontier is one of the last
great wildernesses of North America.

This is part of the largest
temperate rainforest on Earth,

and a stronghold for the country's
highest diversity of megafauna.

Feasting on the abundance
of fleeting summers

to make it through
relentless winters,

both big and small

live here in perfect balance,

their worlds
connected in surprising

and intricate ways that
allow each of them to thrive.

There are still places on
Earth that remain pristine,

where wildlife flourishes.

These are the last regions
that could be called Eden.

For six months of the year,

North America's icy mountain
realm is gripped by winter.

With the arrival of
spring, life stirs once more,

as the world's largest
population of grizzly bears

emerge from hibernation.

A mother with hungry
cubs must hurry

to make the most of
brief times of plenty

in this unspoiled, untamed land.

In spring, the best
feeding opportunities

can be found where it's milder,

along the coast.

Tell-tale footprints
signal the arrival

of newly emerged
grizzly bear families.

After six months of hibernation,

this female and her cubs
are in need of a protein hit.

Twice a day, low tide exposes
a seafood smorgasbord.

A fresh fish looks tasty

but defensive spines mean
it's probably best avoided.

Betrayed by their squirts,
the real prize is the butter clam.

Surprisingly delicate paw work
prevents the clam digging deeper.

Now, add brute force,

et voila, a clam canape.

But when you smell a clam,

and can't find it,

it can be frustrating.

But if you copy mum's technique,

it should work.

Or you could just
use your teeth,

but there may be
some shell in that.

But bears patrol the coast in
search of something other than food.

His cowboy swagger
denotes a dominant male.

All 300 kilograms of him.

And he's keen to kick
off the breeding season.

But a mother with yearling
cubs is in no mood to mate.

A grizzly can hit a top speed of
more than 50 kilometres per hour.

Males may kill cubs to
bring a female into season.

But all that muscle mass

makes it hard to
keep up the pace.

With this overeager
male safely out of reach

the young family
can make the most

of this Eden's other
spring feeding ground,

sedge grass meadows.

While the succulent
shoots provide few calories,

they'll tide a hungry bear over.

Even the cubs are
happy to eat their greens.

But they still
prefer mum's milk.

She'll nurse them
for nearly two years.

All the while teaching them
the dangers and rewards

that come with
this bountiful Eden.

Triggered by spring sunshine,

the first boom and productivity

takes place offshore

as a vast injection of protein
turns the waters a milky white

with herring spawn.

Hundreds of millions of fish
gather in the shallows to breed,

each hen fish
releasing 20,000 eggs.

For resident Steller sea lions,

it's the first great feeding
opportunity of the year.

Flying nearly 1,500 kilometres,
one of the longest bird migrations,

tens of thousands of red
knots arrive from South America,

to take advantage of a feast.

That's also the cue
for marine megafauna.

It's one of the greatest
gatherings of whales on the planet.

14 metre-long grey whales.

Mothers with new-born
calves have navigated

the 10,000 kilometres
from Baja, Mexico,

the longest seasonal
journey of any mammal.

But it's worth it.

In vast mouthfuls
of fatty roe and krill,

each consumes
more than a ton a day.

And so the smallest
creatures here

sustain the biggest,

enabling grey whale calves to put
on a third of their adult body weight

before their autumn
return to the south.

In spring, life also stirs
in this pristine forest

that crowds the shoreline.

Covering over 68,000
square kilometres,

roughly twice the
size of Belgium,

it's part of the largest tract of
temperate rainforest on Earth.

Bathed in nearly 300
centimetres of rain a year,

each 700-year-old spruce
may carry over 200 kilograms

of moisture-loving lichens,
mosses and ferns on its branches.

It's one of the last
places in North America

where prey and predators
exist in equilibrium.

Early migrants like Rufous
hummingbirds arrive.

The climate here is perfect
for sap-rich trees to grow,

so it's worth a 6,000
kilometre journey.

They refuel on the sugary
resin before pairing up to breed

in this most northerly of
all hummingbird habitats.

Yet life here is built on
superficial foundations.

In some places, ice fields only
retreated in the last 200 years,

so the soil is still
shallow and nutrient poor.

But this Eden has an answer.

It's intricate connections
between species

as revealed under the magical
display of the Aurora Borealis.

Flying squirrels emerge from their
tree hollows in search of a mate.

With spring in the air, this
young male sniffs the breeze.

From a neighbouring tree drifts the
heady aroma of a receptive female.

He eagerly sets off
to track her down.

For a flying squirrel,

gliding is the perfect way to get
around this 30-metre high canopy.

In a matter of seconds, the
scent source has been located.

She's just come into season.

But she's playing hard to get.

He'll have to prove
he's a worthy partner.

If he can't keep up,
he's not worth the effort.

But just when it looks like
a match made in heaven,

she decides that he's
failed to make the grade.

Yet, the intoxicating scent
of female is still in the air.

He must find this femme fatale.

The lower he gets, the
more enticing it becomes.

Desperately digging,
this confused Lothario

thinks he's found the
mother of all mates.

But his consolation prize is...

A white truffle?

The furtive fungus omits an odour
that mimics female pheromones.

The truffle tricks
him into solving

the biggest problem for
this mineral starved forest.

When a squirrel carries a
prize truffle to the treetops,

it's spores are
dispersed far and wide.

As they germinate, they help
form a vast underground web

of fungal filaments.

Effectively extending
the range of tree roots,

enabling them to
extract enough nutrients

to allow these great
forests to flourish.

By early summer,

long hours of daylight
promote a flush of growth

across the archipelago's
coastal meadows.

But for grizzly bear families,

high calorie food is scarce.

And aggressive
males must be avoided.

So some head inland

to secluded rivers in
the heart of the forest.

This young mother
has just the one cub.

His siblings may have
been taken by a male.

But she has led him to a
place where he will be safe

and females gather
to feed in peace.

Most are related and
all have young to feed.

But for now, they must wait.

Downstream, along Alaska's
11,000 kilometre seaboard,

half a billion Pacific salmon.

Among the largest
concentrations in the world.

After four years of
fattening up at sea,

some may swim 3,000
kilometres upstream

before spawning in the very
upriver pool in which they were born.

A rich reward for
the eager bears.

Unfortunately for this
young mother and cub,

all the prime fishing
spots are taken

by the older, more
experienced females.

So she leads her cub upstream,
away from the competition.

But there's a reason they
have this place to themselves.

Rapids.

For the cub it's
a brutal baptism.

But the inexperienced mother
coaxes him straight back in.

Her desperation to feed overrides
her urge to protect her cub.

But fortune favours the brave.

Finally, the ravenous cub
gets a first taste of salmon.

Over the next five months,
that the salmon will run,

grizzly bears will eat up to
45 kilograms of food a day.

That's over 50,000 calories.

And this cub will have
the rest of the summer

to master the art of fishing.

Got it.

It's not just the bears that
benefit from this mass migration.

To avoid a catch from being
stolen, the woods offer private dining.

With the fatty head
preferred to everything else,

leftovers litter
the forest floor,

but they won't go to waste.

From nearly a kilometre away,

fishy fumes are picked up

by the sensitive antennae

of a two centimetre-long
indispensable insect.

The burying beetle.

This male has
two things in mind.

Fresh meat and a mate.

But he arrives to find
he's too late to the party.

The good news is that
he's spotted a female.

The bad news is he'll have
to fight other males to win her.

Battles are brief but brutal.

He hurries to claim his beetle bride,
they have an urgent task to accomplish.

Living up to their
name, the new couple

proceed to dig the
salmon a grave.

In the safety of
their cosy crypt,

the pair secrete an antibacterial
saliva to preserve the flesh.

The fresh corpse
provides a feast

for a newly-hatched
brood of larvae.

And there will be plenty of surplus
fish to fertilise the surrounding soil.

In a football field-sized area,

there can be as much as
three tons rotting underground.

Known as fish trees,

spruces grow three times
faster along these rivers.

It's possibly the largest
transfer of nutrients

between water and
land anywhere on Earth.

Because of the sun,
the entire forest prospers.

It's autumn.

The long days and
short months of summer

brought with them great riches.

But now animals that can depart
will soon be journeying south.

Yet for some, this is the
time to secure your bloodline.

Crowned by antlers
spanning two metres or more

and weighing around 18 kilograms

a 700 kilogram moose
proclaims dominion over his realm.

This antler free female

and the five or so
others in his harem

will stick around as long
as he's the best bull on offer.

Younger males go head-to-head,
honing their combat skills.

Though without the impressive
headgear and imposing physique,

they only have a
10% chance of mating.

But one male is
willing to try his luck.

At five years old, he's
almost fully grown,

but he'll never be
a mighty moose.

To win over a female,

he needs a different game plan.

From a discreet distance,

he closely observes what
it takes to be main moose.

The females are in season
for less than two days.

But the dominant male
has a mood-enhancing move

that guarantees romance.

He scrapes a shallow pit

and urinates into It.

It contains potent pheromones
that bring females into season.

They find the aroma
so intoxicating,

they can't resist a roll.

"Ah, so that's how it's done."

Anointing himself
in the musky pee,

this young pretender
seizes his chance.

With the help of
the alpha's aroma,

he gets the come on
he's been dreaming of.

Under the nose of
the moose monarch,

she leads the cheeky
youngster off to mate.

Proving that the smartest moose

isn't always the one
with the biggest antlers.

As autumn gives way to winter,

temperatures plummet to
minus 20 degrees Celsius.

For its remaining
megafauna, like the moose,

it's the beginning of a
long, hard six months

of meagre resources.

Those who don't make it

provide a lifeline for others.

While most rivers
are now locked in ice,

the Chilkat continues to
flow throughout November.

Heated to seven degrees
by thermal springs.

It supports one of
Alaska's last salmon runs,

offering one final
feeding bonan: za,

for America's national bird,

the bald eagle.

Over 4,000 stop off here, in
the largest gathering on Earth,

to fuel up on salmon ahead
of their migration south.

For a young eagle,

this is the first
true test of survival.

Every catch is ferociously contested
by adults much bigger than him.

But to make the journey
ahead, he needs to bulk up.

To avoid serious injury,

disputes are settled
by locking needle sharp,

five centimetre-long talons.

He moves in on the
unguarded carcass,

only for it to be snatched away.

At dusk, eagles retreat to
the safety of the treetops.

They may have
one of the most acute

daytime eyesight's
in the animal kingdom,

but in the dark,
they're virtually blind.

On the ground,

they could easily be ambushed
by nocturnal predators,

like a coyote.

But night may also offer
an opportunity to feed.

Under the safety of
darkness, a mother grizzly

leads her two cubs
to the river's edge.

Brown bears have a membrane
in the back of their eyes

that reflects light
within the lens,

giving them
excellent night vision.

While the cubs amuse themselves,

mum gets on with the
serious business of fishing.

With the coast clear,

the daring youngster
makes his move.

Profiting on the leftovers.

While almost three quarters of
fledglings die in their first year...

this wily eagle has found a
way to gain the strength he needs

to escape the Alaskan winter.

These late salmon runs are vital

to grizzly bears right
across Northern America.

As temperatures drop to
minus 28 degrees Celsius,

icicles adorn their fur.

So they're known here by
the First Nations as Ice Bears.

They've endured the
freezing conditions

for a month or more, waiting
for the salmon to arrive

and many are pregnant.

But if their fat reserves are
too low, they won't give birth.

Every salmon
increases the chance

of surviving the long
winter hibernation.

But across southeast Alaska,
the predictability of the salmon run

has been thrown into doubt.

The damming of rivers,

logging, pollution
and climate change

could mean this
entire habitat is at risk.

On this fragile planet,

home to nearly
eight billion people,

the threat to remaining
wilderness grows ever greater.

But if we take steps
to keep our world safe,

enriched by natural wonders,

it's exquisite symmetry,

kept in balance by
intricate relationships,

these last frontiers...

will remain...

forever Eden.