Original subtitles

(ethereal music)

- [Narrator] From the northern ice scapes

of the Arctic Circle

to the southern most extremes of Antarctica,

winter prowls the earth from top to bottom,

conjuring up seas of wondrous beauty

and stark severity,

breathtaking in spectacle,

but often harsh environments to call home.

Those that do live here thrive here

through amazing adaptations and animal cunning.

It's survival of the fittest,

the fastest and the fearless.

A cycle of life where being strong,

smart, and shrewd can mean the difference

between life and death.

Because in this extraordinary world of ice and snow,

only the most resilient

and resourceful will endure

the Wild Winter.

(wind blowing)

(dramatic string music)

Late September in the Poland North

and as the earth turns away from the sun,

an autumnal twilight sets in.

By mid-October, the tip of the globe

will be in total darkness

and most of the Arctic Circle

will see only glimpses of light.

(tense music)

In Northern Canada,

the coastal landscape has frozen into a jagged ice scape.

Soon the temperature could plummet

to minus 40 degrees Celsius.

Yet polar bears, like this young mother, are on the move

in a relentless hunt for seals.

She and her adolescent cubs

will trek approximately 30 kilometres today,

in search of food.

Just metres beneath the family's feet

is the prey they depend on for survival.

Arctic seals have adapted to stay underwater

for up to 45 minutes,

because to surface is to become vulnerable.

But eventually they need to come up for air.

Who will see the other first?

This is a game many thousands of years in the making.

The bear waits.

The seal holds onto what could be its final breath.

(tense music)

But the bear and the seal are not alone.

(fox calling)

An arctic fox trails the polar bear,

in the hope of scavenging some of her leftovers.

For the fox tagging along,

it's a gamble worth taking.

(bear grunting)

But unsurprisingly, it's not welcome.

The harsh arctic winter

binds the fates of these three animals together.

But the polar bear is this region's ruler.

Little about the weather or wildlife affects her.

To survive and thrive here,

she has adapted from head to toe.

Her double layered fur coat keeps her warm and dry,

blanketing her head, her body and legs,

even her huge dinner plate sized paws.

These hairy feet of hers have adapted to act like snowshoes,

distributing her weight as she walks

and preventing her from slipping or falling

through the ice as she stalks the frozen ocean.

Each hollow hare on her coat is a clear cylindrical tube

that reflects ambient light.

Capturing and storing warm air close to her skin,

preserving precious heat

and creating the artful white camouflage,

that serves her well when stalking prey.

(dramatic drum music)

Spotting a seal emerging for air,

the bear's approach needs to be stealthy.

Her camouflage, an advantage.

(water splashing)

But the seal is not on the ice for long,

and quickly escapes back into the water.

The bear will continue wandering the ice

on her hunt for food.

But the bigger loser is the little arctic fox.

For all the energy he's spent

keeping pace with the polar bear, there's no reward

and he's left out in the cold.

Winter in the earth's high northern latitudes

has many guises.

2000 kilometres north of Norway

is the spectacular Svalbard Archipelago.

Cold arctic ocean currents mix with the warmer currents

that flow from the Atlantic,

resulting in a partially ice covered ocean during winter.

Battered by the winds of the Arctic Circle,

a mother walrus and her calf huddle together.

Resting on floating sea ice

is usually a colder environment for them

than the ocean waters below,

but it's a safer place to be.

The large walrus only has two predators,

polar bears and killer whales.

And in winter,

killer whales stalk the northern oceans

in large deadly pods.

(tense string music)

But to avoid starvation,

walrus must risk potential encounters with the killer whales

and take to the ocean,

because this is where they will find the shellfish

that will sustain them through winter.

Despite the risks,

walruses spend the majority of their lives hunting in water,

returning to the exposed chill of the ice to rest.

But they are perfectly adapted to these conditions.

Their bodies are swathed in insulating blubber,

that can be up to 15 centimetres thick.

Their ears are just small holes.

Having no external appendage helps conserve heat.

Underwater, their torpedo like shape is a lifesaver.

They swim swiftly, and if threatened,

can escape at speeds of up to 35 kilometres per hour.

(walrus grunting)

Their long and strong tusks allow the walrus

to break breathing holes in the ice,

or haul their massive bodies onto drier land.

(bright orchestral music)

Which, between feeding bouts, is where they'll safely rest.

When the oceans of the Arctic Circle freeze,

the marine animals that remain here

all face the same harsh challenge,

ice.

But they have each developed individual ways

of coping with the struggle of life in these conditions.

Here in the winter waters

between Canada and Western Greenland,

the sea ice is hardening and thickening.

For these narwhals, pack ice can be deadly.

(narwhal surfacing)

Narwhals need to regularly surface for air,

but if they can't find a gap in the frozen block,

they will become trapped underwater, unable to breathe.

That's why these males distinctive spiral tusks

are such a vital adaptation.

Sometimes referred to as the unicorns of the sea,

scientists have discovered the narwhals tusk

is actually a supremely sensitive tooth

with 10 million nerve endings.

But this tooth is not for eating.

Instead, it's believed the three metre long tusk

is used as a sensor to read the saltiness

and temperature of the ocean,

making it possible for these fairytale like creatures

to surface effortlessly.

(narwhal surfacing)

(majestic music)

The narwhals near relative

is the equally intriguing beluga whale.

Neither the narwhal nor the beluga have fins on their backs.

This means their bodies have reduced surface area,

helping prevent heat loss,

and without such an obstacle,

they can travel closely under the ice sheets,

giving easy access to breathing holes.

These beluga whales have camouflage on their side too.

While the male narwhal can be easily spotted on the surface,

beluga whales are camouflaged against the arctic ice.

In the years since they were born,

their skin has turned from grey to gleaming white,

a highly effective adaptation to fool predators.

As they dive and reappear,

beluga whales bodies are easily mistaken

for small ice flow, bobbing up and down.

In some deeper water regions of the Arctic Circle,

the winter ice cover can be up to 10 metres thick.

Beneath it, there is total darkness,

with no warmth from sunlight.

But for this hundred year old Greenland shark,

the water temperature is positively invigorating.

Typically, these bottom dwellers spend much of their time

in depths up to two kilometres beneath the surface.

No other shark can tolerate such freezing arctic waters

all year round.

In fact, Greenland sharks purposely migrate

to the ocean's coldest parts, even during winter.

They thrive here in this quiet, almost lifeless environment

and a slow metabolism conserves their energy.

To stay warm In these frigid currents,

the shark's body contains a special chemical compound

that acts like an antifreeze,

preventing ice crystals forming.

No other vertebrate has a lifespan as long as this species,

with some scientists suggesting they can live for 500 years.

Despite this, Greenland shark populations

are thought to have declined and they are currently listed

as vulnerable.

But with no known predators in the wild,

slow and steady is how this fantastic

and fearsome old fish will see out his days.

Deep down in the ocean,

very little changes visually, regardless of day or night.

(bright music)

However, back on land,

twilight signals the end of another short day.

And complete darkness is where the polar north

shows its true colours.

The Aurora Borealis.

Dancing ribbons of light that shimmer and pulse

across the sky,

caused by the sun's energy

interacting with the earth's magnetic field.

This dazzling display

is one of the seven natural wonders of the world.

Few natural phenomena are as spectacular

as the northern lights.

And as a new day breaks across the freezing tundra

of the Canadian Archipelago,

herds of muskoxen make a meal of the lichen and fungi

growing under the snowy surface.

Amongst them, an arctic fox darts around,

not looking for food scraps,

but for the protection the herd can provide.

To save the trouble of creating its own tracks in the snow,

the fox will stay close

and follow in the oxen footsteps,

conserving energy to hunt for its own meals.

The arctic fox is usually of no interest to the muskoxen,

but early winter is a tense time,

particularly when newborn calves

are still young and vulnerable.

Not even the small arctic fox can be trusted.

(tense music)

Winter sees muskoxen move to higher elevations,

where despite the cold, the snow is not as deep.

Here the young males are keen to show off their strength.

So battles like this are common.

(tense music continues)

These beasts are living examples of evolution at its finest.

After all, they are one of the few species

to have survived the last ice age.

Muskoxen bodies are shielded by their billowing hair,

the outer hairs measuring up to one metre in length,

the longest fur of any wild animal.

And they have a second line of insulating defence,

a warm woollen undercoat, that's 10 centimetres thick.

And as for their unusual box-like shape,

it's a simple evolutionary formula

to battle the blizzards.

And this is what will help them live to fight another day

on the barren flats of the Arctic tundra.

(bright light music)

Polar winters are, by their very geography,

the most extreme winters on earth.

But there are other places where winters are less harsh

and more of a beauty to behold.

Winter in Switzerland,

just over 2000 kilometres south of the Arctic Circle,

often brings clear skies and crisp air,

even during the coldest winter months.

Of the many animals that have developed foraging strategies

and thick coats to see them through this time of year,

the Eurasian Otter has to also endure

being cold and wet simultaneously.

(otter squeaking)

In warmer weather, otters spend time in groups socialising.

In winter though, otters like this hungry male

become solitary and nomadic.

Food shortages force them to forage individually,

and cover a lot of territory in their search.

Running streams that present

reliable food sources in summer,

are harder to find this time of year,

with many waterways frozen over.

On bare ground, otters can be a little slow, awkward,

but in soft snow they travel quickly,

gliding along on their bellies.

Often travelling several kilometres cross country,

in their search of food supplying streams.

(wind blowing)

Otters are homeotherms, which means it's a juggling act

to regulate their body temperature,

to balance the heat they lose in the water,

with the heat produced internally.

So plunging into the freezing cold water beneath the ice

could cause their core temperature to drop dangerously low,

if it weren't for their sophisticated waterproof coat.

(bright upbeat music)

The outer layer is a dense weave of interlinked hairs.

And the thick undercoat traps an insulating layer of air,

so their skin stays dry.

The otter dives to hunt for food,

staying warm and dry for up to five minutes under water,

and when they're not hunting or swimming,

they spend a lot of their time preening,

not to look good, but for protection.

Because if their fur becomes dirty,

their coat won't absorb the air that insulates them.

Putting these otherwise hearty animals,

at risk of hypothermia.

(bright piano music)

With the Swiss Alps towering over the lowlands,

during winter,

cold air from the north and moist air from the west

rises above the iconic range,

generating dense snowfall, cloaking the trees and ground.

And in the dim forest light,

the sight of this lone lynx in the Alps

is cause for celebration for conservationists

the world over.

Just 50 years ago, this species was extinct here,

but the cold climate cats have bounced back,

thanks to a Swiss reintroduction programme

and a nationwide hunting ban.

Today, this adult lynx is more at home than ever.

Despite incessant snowfall

and an air temperature of minus 10 degrees,

the conditions are considered relatively cosy

for such a fully adapted feline.

His coat is long and soft For warmth,

his big cat tail is small, to help conserve heat.

And this may allow him to manoeuvre quickly

through dense forest without getting caught or hindered.

And his wide, furry feet provide traction

and can support twice as much weight on the snow,

meaning he's able to stalk his prey with ease.

(animal grunting)

(bright music)

Hunting, travelling, and living alone,

this forest dweller winter adaptations

have created one of Eurasia's stealthiest predators.

No matter the animal or their habitat,

winter tests all evolutionary abilities.

The capability to conserve energy,

maintain body temperature, and secure food sources.

In Scandinavia, the reindeers in this herd

have grown smart seasonal coats,

to withstand the minus 20 degree temperatures

that are not uncommon.

Their coat has two layers, a warm and woolly undercoat

and a hairy top layer.

And like the polar bear,

the outer layer hairs are in fact hollow,

creating a very effective insulation.

So effective, that a reindeer can lie down

without melting the snow under it.

When seen through thermal imaging,

the purple areas of its coat

are giving off barely any warmth whatsoever,

minimising heat loss from their core body.

The areas of white and orange are the most exposed,

in terms of heat loss.

Reindeer possessed something called

a countercurrent heat exchange.

This allows them to recycle heat,

so the heart doesn't need to work as hard.

Like many animals, reindeer have a layer of tissue

behind the retina that reflects light,

enhancing their night vision.

They also have an adaptation

that's never been observed in any other mammal.

The changing of eye colour in sync with the seasons.

In summer, reindeer's eyes are gold,

but in winter the colour changes to a deep blue.

This colour change reduces the amount of light

reflected out of the eye,

meaning reindeer can quite literally see in the dark.

An advantage when it comes to spotting predators

in the low light of winter.

For all their superb adaptations,

reindeer are highly dependent on the health and heartiness

of the great swathes of conifer forest,

mainly as a food source,

but also for protection from the harsh winds

and the freezing cold winter temperatures.

High up in the trees themselves,

there are a whole new set of winter residents,

also managing to combat the cold.

Very few birds remain in the north during winter,

but those that do are hardy.

Colourful Pine Grosbeaks live year round,

in the woodlands in northern America

and the evergreen forests of Eurasia.

Like many birds that live in the forests in winter,

their constant shivering and movement generates heat

to withstand the freezing temperatures.

Though they will travel long distances for food,

Pine Grosbeaks, are a non migratory bird,

living off seeds, fruit, buds and berries,

scarcer during winter.

A remarkably similar looking bird to the Pine Grosbeak,

though not related, is the robin.

Like Pine Grosbeaks,

many robins also stay put during the winter months.

They fluff up their feathers to trap warm air

close to their little bodies.

And they can digest the often unpalatable

waxy berry coatings,

so they gorge happily on any food they can find

at this time of year.

An extendable oesophagus,

also means they can feast on the berries

for as long as they are available,

storing the fruit there, until they settle in for the night.

(light bright music)

The boreal forests that are home to these songbirds,

are also home to spruce, fir and pine trees,

collectively known as conifers.

And these majestic forests of conifers

are as rich and resilient throughout the winter

as they are in the summer.

Unlike other trees that shed their leaves

when the temperature drops,

conifers are evergreens.

Often the branches are hidden under a heavy blanket of snow,

or sometimes covered with delicate ice crystals,

depending on the extremely unpredictable winter weather.

To combat this weather,

conifers enter a type of hibernation,

they stop growing in the coldest months.

Conserving their moisture,

when there's surprisingly little life-giving rainfall.

Their small and waxy needles have adapted

to prevent water evaporating into the atmosphere,

a variation that helps keep them hydrated

through even the bleakest cold season.

(light ominous music)

Living deep within the freezing forests of Finland,

is the brown bear.

During winter, the brown bears food sources

are significantly depleted,

so to avoid the cold weather

and lack of food,

they hibernate.

This brown bear is pregnant

and in a matter of months,

she'll give birth to two or three cubs.

During autumn, she ate to excess,

to build up her fat stores,

built her maternity den,

and is now resting peacefully in it.

Her fat stores will give her enough energy

to live through the winter and to deliver her cubs.

This shelter will be her hideout

for the next six or seven months,

and it's where her babies will be born.

Settled inside, she enters a light hibernation,

or torpor state where she will doze on and off.

She won't eat, drink, or pass waste.

Her pulse rate, breathing and body temperature

will drop to help her conserve energy.

But she'll be on high alert, ready to defend herself

and her unborn, or her newborn cubs if necessary.

She's of a species of bear that's evolved superbly,

to survive these long harsh northern winters.

Her strategy, doing as little as possible.

With the low lying forests of Finland

now in nightfall.

(bright music)

Far to the east, in the Himalayas,

the sun soon dawns

on an entirely different kind of winter's day

for its high altitude inhabitants.

(bird squawking)

Like the polar bear is to the Arctic Circle,

here, 5,000 metres above sea level,

the snow leopard is the top of the food chain.

But when it comes to its prey,

it faces competition from wolves and Himalayan brown bears.

Known to locals as the ghosts of the mountains,

adult snow leopards live a solitary existence,

prowling the steepest and rockiest ridges

of the Himalayan slopes.

Yet they're never troubled by the thin air

of this ultra high altitude.

Thanks to their broad muscular chest,

they can take breaths deep enough

to absorb plenty of oxygen.

As the air passes into their wide nose,

the nasal cavity warms it before it hits their lungs.

The dense, spotted coat offers excellent camouflage

and insulation against the cold.

And the unusually long, thick tail is insulating too.

(tense music)

The snow leopards adaptations do the trick.

Largely unaffected by the wild weather

of their mountain domain

until the comfort of a meal brightens the end

of another winter's day in the high Himalayan mountains.

(bright orchestral music)

As the days start to get longer in the northern hemisphere,

and winter begins its transition into spring

and eventually summer,

below the earth's equator,

the seasons of the southern hemisphere are changing also.

In the far South Pacific,

the temperate coasts and snow capped peaks of New Zealand

have fallen into their own winter season for another year.

And in the alpine country of the south island,

a kea is making the most of its winter's day.

(bird chirping)

A very social bird,

keas often gather in groups at this time of year,

calling out to each other,

as a way of strengthening social bonds.

Listed as nationally endangered,

the kea is the world's only alpine parrot.

As ground nesting birds,

keas are especially vulnerable to attacks

from human introduced species,

such as possums and feral cats.

(jaunty music)

But this intelligent little bird,

called the clever clown of the Alps,

exhibits the problem solving skills of a four year old child

and are known for their mischievous and destructive habits.

Despite these antics, they are much loved by locals,

and easily spotted by the orange colour of their inner wings.

Their olive coloured outer feathers

keep them warm during the colder New Zealand winters.

(majestic orchestral music)

The far South Pacific is as rugged as it is beautiful,

especially during winter,

but for the animals who inhabit the sub-Antarctic islands,

it's also a time of wild seas and wilder winds.

One animal that's perfectly adapted

to make the most of winter's intense weather

is the albatross.

(birds chirping)

Over the coming few months of bitter cold,

this adult female will need to withstand the blustery winds.

Unable to consistently flap their wings,

they use their three and a half metre wingspan

to catch the currents.

A sheet of tendon around their shoulders

locks their wings into place,

helping them glide gracefully,

without expending excess energy.

If the breeze is up, they'll be absent and airborne

for up to nine days, during which time

they can fly up to 5,000 kilometres with ease.

When the winds don't blow, they take time out

to rest on the ocean surface

and quench their thirst with sea water.

This is the ultimate adaptation.

These brilliant birds have a salt gland

near their nasal passage,

that filters salt from the sea water keeping them hydrated

and ready to continue their wanderings,

as they ride the winds of the great southern ocean.

(calm music)

Winter in the southern hemisphere,

also known as the austral winter,

is at its most severe

in the world's southern most continent, Antarctica,

where the ocean is transformed into a place of ice and snow.

Winter in the polar south is extreme,

but awe inspiring.

And so are the animals that live here.

Standing at over a metre tall,

the giants of the penguin world, the emperor penguin,

eats, sleeps and breeds only on the southern sea ice.

They rarely step onto the solid ground

as their colonies are on sea ice.

Waddling rather than walking,

this one's well-dressed for the world's most extreme cold.

Their tuxedo looking feathers form an effective windbreak.

Two layers of plumage

soft down close to the skin,

and shorter outer feathers,

are especially useful when the wind gusts

at more than 100 kilometres an hour.

And despite being an aquatic bird that gets wet often,

the penguins feathers never freeze.

They preen regularly to spread oil

from a gland near their tail,

creating a simple, but practical waterproof shield.

(jaunty music)

That big belly isn't just a convenient way to get around.

This emperor is carrying a bulk of blubber.

And although the largest penguin species proportionately,

they have smaller beaks and flippers than other penguins,

to help prevent heat loss.

With feathers on their legs to keep their ankles warm,

their happy feet are also a miracle of movement.

Fat stalls in the soles prevent them icing over,

even when the temperature's at a bone chilling

minus 50 degrees.

This wondrous creature benefits from inbuilt thermals

and frostbite free feet.

(bright music)

From the penguins of the polar south,

to the polar bears of the Arctic,

what all these cold weather birds,

mammals, and fish have in common is the wonder of evolution.

With smart and sophisticated safeguards,

or protections that are surprisingly simple,

the animals of these punishing environments endure and excel

despite the cold, the wind, and the darkness.

Their bodies have developed in ways

that often seem inconceivable,

but without their amazing adaptations,

none would ever survive the extremes of the wild winter.

(upbeat orchestral music)