Original subtitles

Living in the snow tests animals to the limit.

Our spy creatures are on a mission...

..to understand how animals survive in nature's freezer...

..how they find love...

..care for young...

..use their intelligence.

..and even have fun.

Our spy cams go where few have dared,

to discover how animals

breed and thrive

in some of the snowiest places on Earth.

What seems to us like a magical winter wonderland is very different

for those who live inside it.

And the snows of Alaska can bring extreme challenges.

But one animal seems to relish the cold.

The sea otter.

To discover how they cope with the ice and snow,

they have a new companion -

Spy Otter.

Its subjects are notoriously shy.

Fortunately, there's always one prepared to break the ice.

A male in his prime always checks out new arrivals.

He keeps an eye on all the females.

Spy Otter seems to be going down well.

First introductions over, Spy Otter searches for what he really came

to film...

..a mother with a newborn baby.

Despite the bitter cold, sea otters can give birth midwinter.

Her baby is cocooned in a downy duvet - the densest fur on Earth.

She constantly grooms and blows in air to keep him warm and snug.

Spy Otter will follow the sea otters' story

until the ice melts

and the babies face independence.

For now, she must leave him floating like a ball of fluff

whenever she needs to feed.

She's found a clam - a local delicacy...

..and uses a stone as an anvil to break it open.

It's a technique her baby must ultimately master.

To stay warm, otters haul out to dry their fur at every opportunity.

But with some weighing 45kg, there's only so much

the ice can take.

In Alaska, the weather changes rapidly -

a dangerous time for a mother and baby.

While she tries to cope,

those with fewer responsibilities take it easy.

Otters can eat a quarter of their weight in food each day,

but even that's not enough for a nursing mother.

She must find a meal, whatever the weather.

And with the sea freezing, she can't leave him in the water.

With her baby safe on a raft of ice, she heads

to her favourite fishing spot.

Despite the cold, there's plenty of seafood to be found.

Her pup should be safe where she left him.

But what baby can ever stay still?

..and as the temperatures drop,

the sea starts to freeze.

His mother must find him fast.

But he isn't where she left him.

As the slush turns to ice, the pup is struggling.

All he can do is call for help.

PUP SQUEAKS

But his cries are lost in the blizzard.

Just in time.

Now for some tender loving care.

And for his fur, a thorough blow-dry.

They may have the best fur coats in the world...

..but even they struggle in Alaska's deep midwinter.

The Antarctic presents even greater tests for new parents.

After two months at sea,

these emperor penguins are returning to feed their young.

A penguin-cam joins them as they near the colony.

For a bird more used to swimming,

every step is a struggle.

PENGUIN SQUAWKS

SQUAWKING

When the going gets tough, tobogganing can be a better option.

But here, nothing is easy.

SQUAWKING

Somehow they crossed 50 miles of sea ice to get here.

No other bird endures such hardship to bring back food for their young.

While the mothers were fishing, the fathers cared for their chicks.

A preservative in her stomach keeps fish as fresh as the day

it was caught.

To brave so much to feed these chicks

needs an unbreakable bond between them.

This urge to care is driven by a parenting hormone

found in emperors at higher concentrations than any other bird.

Spy Emperor is proving popular with penguins

who haven't managed to breed.

With no chicks to care for, they're looking for something to do.

They make the same journeys as the other penguins...

..and have a similar urge to nurture.

They'll take whatever is on offer.

Anything new tweaks their interest.

Snowball Cam.

This technical marvel rolls with no visible moving parts.

It even boasts a self-righting lens.

For birds without chicks to rear,

it's an entertaining diversion.

However, Spy Emperor has something even better.

Egg Cam - just what they're looking for.

Their caring nature means it's soon in demand.

SQUAWKING

But there is something even more desirable...

PENGUINS CHATTER

..a living, breathing chick.

It's a time when mothers

are teaching their chicks to walk.

PENGUIN SQUAWKS And how not to.

It's easy for one to get separated.

Penguins can also lose their chicks to bad weather.

These bereaved parents are desperate to find a replacement...

..and they don't care who it belongs to.

Their parenting hormone is as strong as ever.

CHIRPING AND CHATTERING

He's in danger of being loved to death.

The real mother has to fight off a rabble of kidnappers.

Luck's on her side -

propelled from the scrum,

she safely tucks him in her pouch.

In the Arctic winter, bringing up babies can be just as challenging.

To investigate, Snow Cam goes undercover.

Polar bears wear a double-layered fur coat.

Beneath the thick outer shagpile is a thermal lining of denser fur.

But temperatures can reach 40 degrees below,

so bears give birth in dens beneath the snow.

To film the moment they emerge, Snow Cam has a companion.

Blizzard Cam can reach 40mph...

..but this mission requires waiting.

The dens are dug into these snowy slopes.

The only clue to their presence is a snowy mound.

The remote cameras will be triggered by the bears the moment they emerge.

But after two weeks of waiting,

the weather puts paid to that idea.

Or does it?

The mother bear found the spy camera as soon as she left the den.

Her cub is three months old.

They're all alone.

The camerawork is completely down to them.

A bit of reframing perhaps.

That's better.

But a tracking shot - that's really ambitious!

The mother was in the den for six months

and didn't eat the entire time.

Now she must find a meal for her and her cub.

She heads to the sea ice where seals can be found.

Blizzard Cam has beaten her to it.

A young male has just caught a ringed seal.

He eats the blubber first.

It's a nutritious delicacy.

To capture a different angle, Blizzard Cam deploys

the Snowball Cam.

Seals live around the sea ice and make up 95% of a polar bear's diet.

But before the family can taste fresh meat,

they must leave the nursery slopes.

She can smell the carcass from 20 miles away,

but she must take care.

Male bears sometimes kill cubs.

This male has had his fill,

so he tries to conceal the remains from other bears.

But the mother is still on the scent trail.

Despite the dangers,

it's easier for her to steal a meal than hunt one down.

She reached the food just in time.

WIND HOWLS

A blizzard is setting in.

No matter how well protected...

..Arctic weather can test even a polar bear.

But for animals less suited to the cold,

high altitude and snowy weather is just as challenging.

The mountains of Tasmania -

home to a colony

of Bennett's wallabies,

an animal usually found in warmer climes.

Up here, snow is an occupational hazard,

blanketing everything they eat.

They're joined by a new alpine explorer.

Spy Wallaby soon attracts interest from a young male.

Being accepted is vital for any spy.

Wallabies are browsers, and can find food even under a covering of snow.

But when snow comes thick and fast, it's a different matter.

His food is vanishing before his eyes.

Time to head for lower ground.

But some are made of tougher stuff.

A bare-nosed wombat,

another marsupial.

His strong claws soon unearth hidden grass and roots.

Even in the snow, he still patrols his territory.

Although he'll fight off males, a female is always welcome.

He tries the subtle approach...

..but the signs aren't good.

WOMBAT HISSES

The wombat's favourite technique is to bite her backside...

..a move rarely appreciated.

Unsurprisingly, courtship is often a long-winded affair.

As the weather clears, Spy Wallaby's new friend is back.

He's at the age when he's starting to be interested

in the opposite sex.

Nuzzling is part of adult courtship.

It seems like love in a cold climate.

To investigate the courtship of the Alaskan sea otters,

a new spy creature is needed.

Spy Bald Eagle deploys the latest drone technology.

It's disguised to blend in with the locals...

..and provide aerial coverage of otter behaviour.

Groups of female otters

are watched over

by a dominant male, looking

for a chance to mate.

Those with young babies

are usually off-limits.

But the male inspects them all, hoping for an opportunity.

He rarely takes no for an answer.

Spy Otter captures something remarkable -

the male tries to kidnap her baby!

By keeping the baby hostage, he might gain a chance to mate.

The female is having none of it, but rejection leads to frustration.

As things heat up, Spy Eagle swoops in for an aerial view.

The male circles a mother with a newborn.

She pushes him away.

But she's lost hold of her baby.

She tries to rescue him, but the male is back.

He wants to kidnap her baby.

The mother fights him off.

She's finally got her baby back.

This time there was no harm done.

In the Arctic, males with a more fearsome reputation

can show a surprisingly tender side.

These courting polar bears have been together

for two passionate weeks.

Blizzard Cam is finding out how they've been getting on.

The spycam causes hardly a stir.

They have more important things on their mind.

For courtship to be successful, they must mate many times.

The bear equivalent of kissing shows their affection...

..and the female is in a flirtatious mood.

But after two weeks of nonstop passion,

the male is losing his enthusiasm.

She tries again.

A glimmer of interest...

..or perhaps not.

He's completely exhausted.

Time for her to turn on the charm.

It seems the magic is back.

BEARS GRUNT

Perhaps some things are better left unfilmed.

In the Southern Alps of New Zealand,

they do courting differently.

This is home to the world's cleverest bird...

..the kea - the only alpine parrot.

They are very similar to their tropical cousins,

so to survive in the snow,

they have to rely on their intelligence and curiosity.

To discover how they build relationships,

they're joined by a new spy.

KEA SCREECHES

Keas love company but are choosy

on who can join their gang.

Keas have some of the most complex calls of any parrot.

To fit in, Spy Kea tries to speak their language.

SPY KEA SCREECHES

He could have been a little more impressed!

Keas are born in early spring.

By the time the winter snows arrive,

they're the human equivalent of teenagers.

In these gatherings, aptly known as a circus,

keas court each other and learn social skills.

A clever mind also likes to be entertained.

And what better way than making snowballs?

Today they have a new, improved version...

..one with a hidden camera.

Snowball Cam soon puts their intelligence to the test.

KEA CALLS

Passing playthings is a way of making friends...

..and a sign of advanced social skills.

SCREECHING

They love fighting.

But it's all just for fun.

WARBLING AND SCREECHING

Both sexes join in, and no-one gets hurt.

Despite appearances, it's a way to make friends.

Through fun and games, they'll find their perfect partner...

..one that will remain faithful for life.

In Alaska, the otter pup is preparing for the next stage

in his development.

He's learning to swim.

Buoyant as a cork,

he bobs around aimlessly.

Then his confidence grows.

Mother is here to guide him.

She keeps just a few metres ahead...

..then shows what an otter can really do.

As she dives, the air bubbles she blew into her fur for insulation

are squeezed away.

She can hold her breath for five minutes

and dive 100 metres down.

It's not so easy for her baby.

He's losing his buoyant downy fur,

but staying under is still a struggle.

He won't reach the seabed for several weeks...

..and danger lurks below.

Killer whales.

Their young use otter pups for hunting practice.

But an otter can also face danger from above.

Eagles are always on the lookout for vulnerable prey.

EAGLE SCREECHES

A bobbing pup makes an easy target.

The eagle just has to pick his moment...

..one when the pup is alone.

He dives at 100mph.

Saved by his mother.

He's not ready to leave just yet.

For polar bears, independence means the start of a solitary life.

The vastness of the Arctic means they may travel hundreds of miles

without meeting another bear.

But Iceberg Cam has found a young male homing in on the scent

of other bears.

Polar bears are incredible swimmers.

They have been known to swim nonstop for over 200 miles.

He can smell a seal that's been killed by another bear.

There is little left to eat,

but it's a rare chance to socialise.

BEARS GRUNT

And for bears, this means play fighting.

Blizzard Cam soon attracts a bear's attention.

It's something new to play with.

BEAR GRUNTS

But polar bears play rough!

And retreat is the better part of valour.

Fortunately, Blizzard Cam has a decoy.

Its spherical shape makes Snowball Cam far tougher to crack...

..although just as intriguing.

As the bears return to fighting,

Snowball Cam can roll at will.

This is Bear Fight Club - a chance to test their strength

and practise moves that one day they'll use in earnest.

Snowball Cam is right in the thick of it.

Soon they'll be fighting over females,

then things will really get serious.

Now they even have time for a game of football.

They should enjoy it while they can.

Soon they will be rivals.

It's the price of growing up.

The hardest part of becoming independent is leaving home.

The emperor penguin chicks are about to take the biggest step

in their young lives.

Left alone by their once doting parents,

they must leave their icy birthplace

and make their way to the sea.

Every test they face hones skills they'll need later in life.

But one challenge stops them in their tracks...

..a giant petrel.

They try to flee, but running isn't an emperor's strong point.

A slip is all the petrel needs.

CHIRPING

The chick is grabbed by his neck feathers...

..but the down just falls away.

They form a defensive circle and prepare to stand their ground.

Despite their chick-like appearance, they are close to a metre tall.

Quite a size, even for a giant petrel.

The chick towers to full height, protecting those behind.

His defiance buys time.

It's a standoff.

Then, as if from nowhere,

an Adelie - the feistiest penguin in the world.

He fearlessly puts himself between the chicks and the petrel.

Even petrels don't mess with Adelies.

Their plucky rescuer accompanies the chicks to the sea.

Emperor Cam is there to see them on their way.

But entering the water is a daunting prospect.

Having an adult around must be reassuring,

even if it is a spy.

Another Penguin Cam is also ready to see them go.

Instead, other penguins start to arrive.

More Adelies. Their rescuer was just the frontrunner.

It's the Adelies' turn to breed,

and they don't want the emperors around.

So they offer some gentle encouragement.

SQUAWKING

It will be four years before the chicks return to breed.

The new arrivals don't waste any more time.

They head to their summer breeding grounds, and the cycle begins again.

Spring is arriving in New Zealand, and the keas are growing up.

For them, adolescent life is one of continual learning.

Like teenagers, they do everything together.

And spring brings new opportunities.

Meltwater creates a drinking pool.

If you can find it, it's a facility open to all.

It helps to have friends in the know.

Spy Kea is now one of the gang.

Though they still don't seem quite sure what to make of him.

It's more than a source of fresh mineral water.

It's a natural spa.

Even brainiacs like to relax sometimes.

But it's not long before they're exploring again.

Anything new is irresistible for a fertile mind.

How hard can it be?

So, this controls the head...

..what about this one?

SPY KEA CALLS

If you're growing up in the snow,

it certainly helps to be smart.

It's also spring in Alaska, and the snow is starting to melt.

Pups born in a harsh winter

now face independence.

For the last five months,

this pup has depended solely

on his mother for survival.

Together, they've dined off a seafood platter of crabs and clams.

But he's so used to the good life, he's reluctant to fend for himself.

Far easier to steal from Mum.

But some shells are just too tough to crack.

In her final act of dedication,

she must teach him to find and break open his own food.

She dredges the seabed for a suitable stone...

..and places it on her chest to use as an anvil.

Only a few mammals use tools,

and it's something her pup has to master.

It's his turn to give it a go.

But he seems to have chosen

the biggest rock in the bay!

It's a struggle just to lift it,

let alone use it as a tool.

His mother watches over him

as he tries to break the clam...

..then shows how it's done.

He mimics her actions.

Then, finally, he cracks it.

With his mother's help,

he's learned all the skills

a young otter needs to survive.

He's ready to face the world.

Growing up and surviving in the snow requires resilience...

..intelligence...

..curiosity... PENGUINS SQUAWK

..and sometimes a playful nature.

But to film their lives tested our spy cameras to the limit.