Original subtitles

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(Narrator) The largest land predator on earth

faces a fearsome enemy.

Climate change threatens polar bears throughout the Arctic.

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A world once frozen for much of the year

is increasingly free of snow and ice.

And the sea takes weeks longer to freeze.

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While some residents of the north are forced to adapt...

Others thrive in this changing habitat.

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Young bears gather knowledge from their mothers.

Learning how to stay alive in times of famine.

And how to avoid deadly encounters.

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Today, polar bears are under unprecedented stress...

And need to find new ways to survive in a warming world.

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It's November in Western Hudson Bay.

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And this young male polar bear has a problem.

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The ice, which should be forming by now

is nowhere to be seen.

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Cape Tatnam, on the shore of Hudson Bay,

is the summer home of part of the world's most

southerly polar bear population.

The bay is normally frozen from November to June,

and the bears live out on the ice,

hunting mostly ringed seals -

one of their favorite foods.

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In the summer, some seal species move north seeking ice,

while others disperse to areas along the shore

where they're difficult to hunt.

At Cape Tatnam, the main food source of

polar bears vanishes, until the ice returns.

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The long, ice-free season has been an especially

tough time for this young male.

This is his first year without his mother.

Last winter he would have traveled with her across

the vast, frozen surface of Hudson Bay,

learning how to hunt.

This spring, two years old and able to fend for himself,

she chased him away,

so she could mate again.

Since then, he's had to find food the way

all adult polar bears do - alone.

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He still has a lot to learn...

Like how to navigate thin ice.

He's been born into a dangerous time.

2016 is the warmest year on record.

Climate change is wreaking havoc across the North.

It's now late November,

and the temperature in Western Hudson Bay is

about 18 degrees Fahrenheit warmer than normal.

It needs to be colder for seawater to freeze.

And this year in November, the extent of the sea ice

is the lowest it's ever been since 1978.

More ice-free days mean this young bear's

first solo seal hunt is perilously delayed.

If Hudson Bay doesn't freeze over soon,

he's in danger of starving to death.

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While mostly dependent on their own fat reserves

during the summer and fall, polar bears in this region

have adapted to eating less nutritious food,

like grass, seaweed or bird eggs.

But they're not born with this knowledge,

and must learn this behavior from their mothers.

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The young bear picks up some kelp to sate his hunger,

as he probably watched his mother do.

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He has to be careful...

Because he's not alone.

These willow patches along the shore

are hotspots for adult males.

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Adult males are cannibals.

They're known to prey on juvenile bears.

Bears from hundreds of miles away

have converged on the area.

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During the winter,

about 4,300 polar bears spread out

across the vast ice of Hudson Bay.

But during the summer and fall,

about 1,000 cram into this relatively small area

in Western Hudson Bay...

Averaging almost eight bears per square mile.

It's an extremely tight arrangement that's

especially difficult for juvenile bears.

It's the first time the young male has interacted

with the much larger adults in the willow patch.

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Polar bears have distinct personalities.

One might be more timid...

While another is outgoing.

Some may be moody...

While others are more playful.

And they form complex relationships with each other.

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Play is a vital part of polar bear life...

Especially for the males.

Among this unique group of bears,

who come together here every summer,

it creates bonds that can last a lifetime.

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Bears can play for hours.

But this friendly skirmish is over before midday.

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The bears have wasted enough precious energy and

settle down for a nap.

During these lean months,

they have to conserve their strength.

With no seals to eat, bears can lose up to

two pounds of body weight every day.

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In the summer, the bears in Western Hudson Bay are

unable to hunt seals for about 150 days each year.

If that threshold is pushed by just thirty more ice-free days,

up to fifty percent of young bears could die of starvation.

The Western Hudson Bay population has dropped

nearly a quarter, from 1,200 to 900 bears

in the last three decades.

Mothers and their nursing young are hit the hardest.

Two thirds of litters are twins.

And protecting two cubs at once is a very tough task.

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This mother has done an impressive job

keeping both her cubs alive.

But she's exhausted.

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For the first three or four months,

her cubs nursed up to six times a day.

Now, almost a year old,

she nurses them less regularly.

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It's been over four months

since Mum's eaten a fatty seal.

The nutrition in her milk is depleted.

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The cubs' scruffy appearance is a sign that they are

spending too much time on land

waiting for the ice to come.

The mother would normally keep them clean.

But along these muddy shores,

it's a near-impossible task.

A year ago, the young male

had his mother to protect him.

Alone, he could be in danger.

Even at 550 pounds,

he's still not too big for the adult males to kill him.

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The average life expectancy of these bears is about

18 years, though some live even longer.

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They sleep in the willow brush with the supreme

confidence of an apex predator.

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The young bear warily lays down among them,

keeping an eye out...

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But he's chosen a dangerous neighbor.

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The much bigger male approaches him.

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He hangs his huge head low and hisses and snorts...

Clear signs of aggression to the young bear.

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Polar bears tend to avoid confrontation,

but adult males are notoriously volatile.

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The situation for this juvenile

could suddenly turn deadly.

He retreats...

To where the big male can't follow.

Onto thin ice.

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It's been so warm, even shallow lakes and ponds

are barely frozen over.

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He's already an expert ice walker,

with huge paws, up to 12 inches across.

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His black footpads are covered with small,

soft bumps that grip the ice and keep him from slipping.

Tufts of fur between his toes and long claws

also help him with traction.

Spreading his legs, the young bear attempts to

distribute his weight more evenly.

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He tests the ice,

something he probably learned from his mother.

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The big male decides not to follow.

This late in the year, conserving energy is crucial.

Just walking expends

13 times more energy than resting.

Instead, he dedicates some time to personal grooming.

Polar bears take extremely good care of their coats.

Matted, dirty, and wet fur

is a poor insulator.

The prickly willows are a natural hairbrush and

after some determined scrubbing,

he's good as new.

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This mother and her cub have been walking all day.

As most litters are twins,

she likely had another cub that died -

possibly killed by an adult male bear,

or through starvation, or even by wolves.

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Almost half of the cubs in Western Hudson Bay

don't survive their first summer.

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Now this mother and cub are looking for something to eat

and for a safe place to rest.

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She approaches the willow patch with caution.

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She carefully weighs her options -

a potential resting place versus dangerous males.

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Her cub doesn't understand the seriousness of the situation.

She's busy imitating mum.

Balancing on two legs is still a bit of a challenge.

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Cubs in Hudson Bay spend about two years with their mothers,

who pass on knowledge for survival,

both on and off the ice.

Polar bears have exceptional memories.

They can recall landmarks in places that are

under snow and ice half the year.

Anything the mother teaches will be critical for the cub

once she is on her own.

As the mother's attention is focused on the males...

Danger approaches from behind.

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A lone timber wolf has been tracking the two bears all day.

She's trailed them through the willows...

Perhaps hoping the mother might be too exhausted

to defend her cub.

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She would never be able to overpower the mother.

But she could outsmart her with stealth and cunning,

and kill the cub.

Sneaking by, she seems to weigh her chances.

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But any aspirations are futile...

Both mother and cub are healthy and alert.

Clearly not threatened, the mother gives her

but a passing glance.

Finally, they can settle in for a nap.

The wolf moves on, looking for easier prey.

Wolves are opportunists, hunting alone or together,

to kill any prey they encounter.

Even though they're considered highly intelligent,

they still sometimes go days without success.

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As winter approaches, the wolves are in a race

against time to build up fat reserves.

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Blizzards will soon cover everything here in a

deep blanket of snow, making hunting difficult.

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The lone wolf will have much better odds focusing on the

muskrats living in this marshy pond.

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Muskrats normally live in groups consisting of a male,

a female and their young, up to eight in each litter.

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Their carefully constructed lodges are made of mud and

vegetation, and can be up to 3 feet high.

Their entrances are under water,

so land predators can't get in

when the marsh is fully frozen.

Now, the muskrats take advantage of the

prolonged warmth and partially open water

by doing some home renovations.

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Staying downwind, the wolf sneaks up

to pounce on the unsuspecting rodent.

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A muskrat can stay underwater

for up to 15 minutes...

And with multiple push-ups and holes in the ice

to choose from, the wolf has no way of knowing

where or when it will surface again.

Today has not been her day.

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(Howling)

But tonight, her pack hunts again.

(Barking & Yipping)

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Morning reveals the mauled remains of their kill...

A moose, and there's little left.

Wolves can eat up to 20 pounds of meat in a single meal.

This female moose is small,

and weighed about 330 pounds.

The pack must have been ravenous.

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The mother polar bear wakes from her slumber.

Her sensitive nose has caught a dangerous scent.

This time, she immediately knows it's serious.

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She and her cub need to leave...

Now.

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A big male is interested in the duo.

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Heading out onto the tidal flats,

the mother aims to put some distance

between them and the male.

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She shields her cub behind her body.

To the male, her body language is clear:

"If you want my cub, you'll have to go through me."

The male appears undecided.

He examines the place where the pair was resting more closely.

He sniffs and rolls in the spot,

saturating himself in the scent of the female and her cub.

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The mother watches his every action,

trying to anticipate his next move.

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Suddenly, the male goes into pursuit.

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Mother and cub panic.

And the race is on.

It is a battle of stamina and determination.

His hunger pitted against her resolve

to keep her cub alive.

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The chase continues all day across the muddy tidal flats.

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Survival comes down to one thing:

how long her cub can run.

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The male's in no hurry.

He's bigger, stronger,

and he should be able to outrun them.

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The mother refuses to give up,

and her cub seems to share her tenacity.

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By evening, the male falls back.

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Whatever swayed his decision...

Mother and cub are safe...

For now.

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A "supermoon" looms large.

It's when the full moon orbits closest to the earth.

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It hasn't been this close in almost seventy years,

resulting in higher than normal tides.

The ocean is in upheaval...

And it's still not freezing.

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The following morning, the young male from

the willow thicket seems wary and restless.

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Last year, when the sea didn't freeze,

his mother most likely took him along the coastline...

Further north, where they finally found ice,

and could venture out to hunt seals on Hudson Bay.

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Now, he sets off on his own,

with only his memory to guide him.

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While the bears wait for the ice to arrive,

and the lean times to end...

This red fox has had a banner summer,

gorging on lemmings, eggs, and young birds.

But in the coming brutally cold winter,

most of his prey migrates, hibernates,

or is blanketed in snow.

In preparation, he's stashing supplies everywhere.

Burying food in numerous holes,

2-4 inches deep, to last all winter.

If another animal finds a cache,

at least he won't lose his entire supply.

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There's a lemming colony nearby.

It's hard to catch what he can't see.

But the fox, unlike most mammals,

can hear low-frequency sounds extremely well.

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He listens intently, and picks up on tiny noises,

including lemmings scampering three feet

under earth and snow.

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But today, the lemmings elude their adversary.

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After escaping the male pursuer,

the mother bear relaxes and cleans her fur.

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Her young cub mimics her every move;

it's a critical lesson.

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A clean coat is vital to keeping warm

in the winter months.

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But for the young cub, it's mostly fun.

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A blizzard zeroes in on Western Hudson Bay.

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Winter conditions are finally on the way.

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On his long journey north, the young male seeks shelter.

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He digs a bed in the lee of a ridge.

Any snow piling up on top of him

provides an insulating blanket.

He could stay here for days,

snoozing right through the worst of storms.

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But this blizzard passes quickly...

Too quickly.

The temperature still doesn't fall enough

to begin freezing Hudson Bay.

No ice means no seal hunt.

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Against the ticking clock of starvation,

the young bear continues on his quest.

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While polar bears spend the majority of their life

on the move, ruffed grouse don't venture far from home.

Summer or winter, they spend their lives

within just a few acres.

While the bears go hungry, these birds take

full advantage of the late arrival of winter.

Dense stands of young willow,

alder and poplar are a grouse's favorite.

Their buds are its staple winter food.

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This grouse got lucky:

it's found some leftover cranberries.

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When it comes to winter adaptations,

it's tough to beat the ruffed grouse.

Fleshy projections grow on the sides of their toes

in the fall, like natural snowshoes...

Giving the grouse a firm grip on icy branches.

They can easily withstand the bitter cold.

Puffing up their feathers, they sit almost motionless -

unseen to predators.

When the weather gets too severe,

they burrow in the snow, and can wait out

the entire winter in this cozy huddle.

Early December, as the days become shorter,

the temperature finally starts to drop.

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The ocean water begins to freeze...

Forming small needle-like ice crystals called "frazil."

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These crystals are tiny,

only an eighth to a quarter inch.

But when they accumulate in the thousands at the surface,

they have the power to turn the ocean into ice.

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This morning, the incoming waves are transformed

into what's called grease ice.

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The ocean is roiling as if fighting itself.

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Out in the rougher waters,

grease ice can't fuse into a continuous blanket.

This slush forms circular disks.

The first pancake ice of the season rides the surf.

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In smaller inlets, grease and pancake ice

near the shore begin to consolidate and

bond into larger sheets.

If the temperature continues to drop,

it will be only days now until Western Hudson Bay freezes.

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For the mother with two cubs,

it won't come a moment too soon.

She's grown more gaunt with each passing day.

Even through her thick coat, her hip bones jut out.

The family has taken advantage of

the freshly fallen snow,

and the cubs have cleaned up nicely.

As they grow, they become more independent.

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Each has a mind of its own,

and their distinct personalities are beginning to show.

While one is more cautious, sticking close to mum...

The other walks ahead, undeterred.

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Mom remains on constant watch,

and eventually convinces her adventurous youngster

to rejoin her for protection.

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Five months have passed since the family tasted seal meat.

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Their mother's milk is depleted.

Their need for nutrition is now a matter of life and death.

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She leads them to the rocky shore.

They'd much prefer seal over seaweed,

but they don't have a choice.

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With a longer ice-free period,

the sight of one of the world's fiercest predators

grazing on seaweed is becoming more common.

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If the climate trend continues,

these young polar bears will have to do much more

foraging than their mother ever did.

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Finally, the temperature plummets.

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Overnight, the sea locks into a solid sheet of ice.

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The freeze-up is about three weeks late.

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The young male made the right decision to walk north.

His gamble has paid off.

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Soon, the seals will be returning with the ice.

He's made it through his first summer alone.

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Now, he ventures out on

the start of a new phase of life...

His first winter alone, hunting seals...

On the frozen expanse of Hudson Bay.

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