Original subtitles

(THUNDER CRACKS)

TOM HARDY: Predators across the planet,

unmatched in strength... (ROARING)

...speed,

strategy,

stealth, and teamwork.

But staying on top is never easy. (LION GROWLS)

(LION CUB GROWLS) As the world around them changes,

they must adapt faster than ever before

to maintain their rule. (LION GROWLS)

(SNARLS)

(ANIMALS GROWLING AND GRUNTING)

In sub-Arctic Canada, the largest bears on earth...

(GRUNTS) ...dominate.

(ROARING)

From the smallest cub to the biggest males,

they face one common enemy. Hunger.

Every year, the polar bears of Hudson Bay

travel hundreds of kilometres across the frozen sea to hunt seals.

(CALLS SOFTLY) But time is against them.

As summer approaches, the sea ice melts away...

...forcing them back to land,

where they must master a new world until winter returns,

or face an uncertain future.

The end of autumn on the western shore of Canada's Hudson Bay.

Home to a bustling community of 1,000 polar bears.

Made up of mums and cubs,

boisterous teenagers, and solitary adults.

With its rugged shoreline,

and vast waters,

Hudson Bay is an extreme place to live.

(WIND HOWLING)

Temperatures here on land are beginning to drop.

And the entire bay starts to freeze.

Nanuk, a young hungry bear,

is being forced to live on land...

...where food is scarce.

But five months of famine has weakened him.

He is losing roughly a kilo of body mass a day.

While he's desperate to move out onto the ice,

it's not yet solid enough to hold his weight.

As the bay begins to freeze over,

the atmosphere is tense as more bears begin to gather.

Pukak, a rival bear, begins to size up Nanuk.

(BIRD TRILLING)

(WIND HOWLING)

They are both famished.

(GROWLING) Nanuk must stand his ground.

At almost 400 kilograms, both bears are heavyweights.

Nanuk steps into the ring and strikes a mighty blow.

(ROARING)

(BOTH ROARING)

It may look brutal...

(ROARS)

...but the aim is not to inflict injury.

Nanuk's goal is to pin his opponent to the ground.

Determined, he gains the upper hand,

throwing all his weight upon his rival.

(ROARING)

Pukak is overpowered.

(WHIMPERING)

Nanuk has won.

Play-fights like this cement Nanuk's place amongst the other males

and gain him essential fighting skills.

(GROWLS)

Having asserted his dominance,

he now needs to conserve energy

while he waits for the bay to freeze.

Hudson Bay is undergoing

one of the most dramatic seasonal changes on Earth.

With the sea freezing solid,

forming ice three times the size of the United Kingdom.

But it's not only bears that call this frozen desert home.

They share it with the seals that raise their young here.

The prey of choice for this predator.

Nanuk is not alone hunting on the sea ice.

Polar bears of every generation are on the move.

From seasoned veterans...

...to first-timers.

And after weeks on the ice, this young male bear

is still getting to grips with locating seals.

This could take some time.

His prey number in their thousands,

and they can only be reached through cracks and holes in the sea ice.

Lying in ambush

can be a long and fruitless wait.

(GRUNTS)

It's better to keep on moving,

using his acute sense of smell to track down his next meal.

(GRUNTING)

His compulsion to hunt drives him to search

for any signs of seals above and below the ice.

But swimming is hard work,

sapping his already depleted energy levels.

Finally, a seal within his sights.

But this bulky bear makes for a less than ideal sprinter.

Hunting relies on the element of surprise.

(BIRDS SQUAWKING)

But bad timing.

A flock of birds draws the seal's gaze to him.

(WATER SPLASHES)

While he spends most of his life in the pursuit of this prey,

most hunts are unsuccessful.

(ICE CRACKING)

His quest continues.

Until he finally picks up on the scent he's been craving.

Despite being almost invisible from the surface,

he has located a seal den under the ice.

(THUDDING)

He pounds at the den roof, desperate for what's below.

(ICE CRACKS)

Success.

At last, he can feast.

It's a promising start for the first bears out on the ice.

If they are to pile on enough weight to survive when the bay is ice-free,

they need to work fast and catch many more seals.

But in recent years,

a warming climate has altered their world,

reducing the length of time they can hunt on the ice.

Five hundred kilometres west,

back on land, it's now March.

Whilst most of the Hudson Bay bears have been hunting on the sea ice,

a small group of pregnant females have remained inland.

(WIND HOWLING)

This single mum has carefully dug out a den

for herself and her two cubs.

Her encounter with a male last year resulted in the birth of her twins.

(SCREECHING SOFTLY)

Tala is the smaller cub

and bears the brunt of big brother Sika's playful scuffle.

(WHIMPERS SOFTLY)

He takes a bite, letting Tala know who's boss.

(WIND HOWLING)

Both baby bears are totally reliant on their mother for milk and warmth.

Her cubs must feed on her fat-rich milk

every three to four hours if they are to survive.

She has not eaten since she entered the den eight months ago.

And there is no food for her here.

Soon, she will have to take the cubs and leave.

But judging when to go is a huge decision.

If she leads them on this journey too soon,

they may not be strong enough to survive.

If she leaves it too late, they will starve.

And with a storm building,

the bears will be going nowhere today.

(WIND HOWLING)

(BIRD CALLING)

TOM HARDY: As the skies clear,

the Northern Lights dance above the polar bear family as they sleep.

(WHISTLING)

(WHOOSHING)

Thankfully, the next day is perfectly calm.

Mum seizes the opportunity to start their journey.

While big brother Sika runs ahead,

Tala's small frame is holding him back.

(GRUNTS)

(WHIMPERS)

Mum offers him some gentle encouragement.

After a few days of non-stop walking,

Tala is exhausted.

Driven by hunger, they all push on.

But they still have a gruelling 80 kilometres

before the start of the shoreline.

From there, almost a million square kilometres of ice

lies ahead of them.

If they can make this arduous journey,

they will have the chance to feed on seals.

(CUB CALLS SOFTLY)

After five days, Tala is pushed to his limits.

He and his brother are constantly demanding food,

and it's slowing their progress.

All tired little Tala wants to do is feed and rest.

But after only a few minutes, he is moved on.

Sika bounds ahead whilst Tala tries to keep up.

Incredibly, after eight days,

they reach the coast,

As the whole landscape is covered by a blanket of snow,

it is difficult to see where the frozen land finishes

and the sea ice begins.

(WIND HOWLING)

Around the Hudson Bay,

other polar bear mums and new cubs are emerging,

some with even more mouths to feed.

All are bound for the sea ice.

(SNIFFING)

(WIND HOWLING)

This mother expertly navigates

the ever-shifting landscape of ice as it breaks up,

moves, and refreezes.

But negotiating it with two small cubs

is a different challenge.

Despite her best efforts, they are easily distracted.

And these shallow meltwaters are the perfect playground.

(GROWLING)

Even at this early age,

these cubs are developing their fighting skills.

While the cubs play,

their resourceful mum searches for a snack to tide them over.

Beneath the surface, she finds them mineral-rich sea kelp.

It's enough to distract them from their game.

(SQUAWKING)

After her dip, a roll in the snow

is an opportunity to teach the cubs how to dry off.

(CUB SQUEALS) But she can't afford for them to hang around.

As the weeks pass,

she experiences the thaw sooner than expected.

It's an early spring melt.

This is potentially devastating for her cubs.

The less time she has to catch seals,

the less likely her cubs will survive their first year.

If climate change continues at its current rate...

(ICE CRACKING)

...the situation will only get worse for this family.

Traversing this icy landscape has turned dangerous.

(GRUNTING)

They can no longer trust the ground beneath their feet.

(ICE CRACKING)

Wading through icy water is now a necessity.

It's a life-or-death challenge for the tiny cubs.

(CUB WHIMPERS)

(CUB WHIMPERS)

But what they are about to face is on an entirely different level.

(SQUAWKING)

Within weeks,

the sea ice between the bears and the land breaks up,

creating millions of shrinking islands.

The family are now almost 300 kilometres from land,

in the centre of the bay, on the remaining ice.

They must time this perfectly.

If they depart too soon,

they will not have eaten enough seal blubber to last the year.

If they leave it too late,

the cubs will not survive the long swim back to shore.

It's just as well that Mum has found her stride...

...providing the cubs with food on the move.

From nutritious kelp to nourishing seals.

(ROARS)

As they pile on the kilos,

with each day that passes,

the swim back to shore grows longer.

But despite her best efforts,

Mum has run out of time.

As the seals return to an ice-free ocean,

the Hudson Bay bears have no choice

but to commence their own journey back to land.

One lone polar bear is ahead of the family.

He's had a successful season

and is the heaviest he will be this year.

The ice beneath his feet thins

and is already beginning to give way beneath his weight.

(SQUAWKING)

Arriving at the frozen edge,

he is confronted with nothing but open water.

But he has no idea of the exact distance

between him and the land.

Over the next month,

all the polar bears of Hudson Bay begin their journey.

Some over the remaining ice,

others endure an exhausting swim.

They will either reach the land

or die trying.

TOM HARDY: It's July,

and five months before the ice returns.

Many of the Hudson Bay polar bears have made it safely back to shore.

These are the lucky ones.

Some did not survive the swim.

For those that did, the landscape is transforming.

As the last of the ice melts,

temperatures are rising.

Everything awakes from its winter slumber.

Summer has arrived.

(BIRDS CHIRPING)

Many creatures emerge from hibernation

or migrate thousands of kilometres to feed here.

(SQUAWKING)

Now is a time of plenty for some,

with food in abundance up and down the coast.

But while these animals have everything they need,

this family face a time of hardship.

With the seals far out of reach in the ocean,

the bears' fat reserves are their lifeline.

The mother continues to hunt for her family...

(BEAR ROARS)

...but most animals here on land are too quick for her to catch.

And so are just not worth the energy.

(BIRDS SQUAWKING)

(MOTHER BEAR HUFFING)

It is time for this apex predator

to transform from hunter to gatherer.

Lush grasses offer a welcome snack.

But a plant-based diet can only do so much.

Weight loss is inevitable.

(BEES BUZZING)

It's August now, and four months before the big freeze.

This young male, Arktos,

is one month into his new diet.

He is losing weight, and fast.

(DISTANT HIGH-PITCHED CALLING)

As he scours the landscape for food,

a unique call entices him up the shore.

He hones in on its source as it might provide a lifeline.

(HIGH-PITCHED CALLING)

Unbeknown to him, under the waves,

thousands of beluga whales have travelled here to give birth.

(WHALES CALLING)

This is a fleeting visit of just weeks.

Arktos has to figure out how to catch one.

Groups of whales pass him by, far away from the shore.

His only option is to plunge into their world.

But the tide is strong,

and his prey swims out of reach.

Time to rethink his tactics.

He needs a vantage point if he wants to surprise them from above.

But this prime spot from which to hunt is prized.

And an older, more experienced male, Ursa,

wants the rock for himself.

(ROARING)

Contesting this is no play-fight.

(ROARING)

Out of his depth, he is defeated.

And Arktos has no choice but to head back to shore.

But perhaps he can turn this setback to his advantage,

and Ursa can show him how it's done.

Silent and patient, Ursa waits.

Timing is everything.

Each passing whale presents just one chance.

Belugas drift close to his rock,

unaware of the danger he presents.

Ursa prepares to pounce.

He must be deadly accurate.