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Full EpisodeSnowbound: Animals of Winter

The coldest and snowiest places on earth pose a challenge to anyone visiting such locations as the Arctic Circle or Antarctica, but what about the year-round animal population? How do they cope for many months with life in these frozen wonderlands where temperatures can plummet to as low as minus 50 degrees? Gordon Buchanan, a wildlife cameraman used to filming in frigid lands around the globe, explains how creatures like the wolf, Arctic fox, bison, reindeer, lynx, weasel, polar bear, penguin, Weddell seal, and woolly bear caterpillar adapt to their surroundings or employ clever tactics to survive.

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♪♪ BUCHANAN: I'm Gordon Buchanan, a wildlife cameraman.

I've filmed in some of the planet's most extreme and bitterly cold places.

Despite being so harsh, these frozen wonderlands are full of life, with creatures that somehow manage to survive against all the odds.

I'll be meeting some of these fearless animals, from sociable wolves to the enigmatic lynx and cunning Arctic foxes.

That is the most sumptuous animal I've ever seen.

These are creatures that are specially adapted and have evolved to live in the snowiest, coldest places on Earth.

How they're able to survive the big freeze is extraordinary.

♪♪ ♪♪ BUCHANAN: I'm in the Arctic.

It is incredibly beautiful, but it is also incredibly cold.

Winter temperatures here can drop to as low as minus-50 degrees.

Yet for some creatures, like these magnificent wolves, they call this place home.

They live on top of the world in one of the earth's freezers... the Arctic Circle.

I'm in Polar Park in Norway, the most northerly wildlife park in the world.

The wolves here have grown up with humans around, so they're used to people.

But I still need to gain their trust and have to remain quiet and calm.

Despite the cold, I've had to take hat and gloves off or these guys would be too tempted to snatch them off.

Hello.

[ Wolf whines ] This magnificent beast is treating me like another wolf and saying hello.

That's how they greet each other -- with their mouths.

Wolves often nibble on each other's faces.

It might look aggressive, but it's a sign of affection.

The size of the paws.

You are a beaut!

Just stroking this wolf, you can lose hand in its coat.

And when I part the hair, you can see the underneath, these fine, very soft hairs that gives insulation, and these longer, outer hairs repel the snow and water.

His coat is perfect for these conditions.

But like the domestic dog, the foot pads, the toe pads of the wolf are completely naked.

And they spend most of their lives with those naked toe pads and foot pads in contact with the snow and ice certainly in the winter.

So how do the wolves stop that cold temperature coming from the ground up through their naked feet into the rest of their body?

Well, they've got a very, very clever solution to that.

Hot blood never reaches a wolf's paws.

As it flows down the leg, it's cooled down -- almost like entering a fridge.

Only cold blood is kept within the paws so that all the warm blood can remain within the body.

This clever adaptation means that any heat loss is kept to an absolute minimum.

On a thermal camera, which shows body heat, the upper part of the wolf's legs are red, showing them to be warmer than its feet.

The wolf's coat looks blue.

That's because his stunning thick fur is preventing heat loss from his body.

So no matter what physical characteristics you have, a clever hunting strategy is essential.

And in these bitterly cold conditions, it helps to have friends.

A wolf's ability to hunt as a team, as a pack -- that's really what helps guarantee its survival.

Being part of a strongly bonded pack is invaluable in the coldest part of winter.

[ Wolf howling ] In North America, this pack have been waiting until their prey is at their most vulnerable.

[ Elk bugles ] The elk here are weak with hunger and in such deep snow, they struggle to run very fast.

[ Elk bugles ] The wolves follow a well-practiced formula.

They target a straggler of the group.

Three members of the pack work together to bring the elk down.

It's a brutal but impressive hunting strategy.

Impeccable teamwork, along with remarkable adaptations, make wolves stand out as supreme snow animals.

Not all snow animals live in social groups like wolves.

In fact, one of the most successful snow animals is solitary and lives most of his life alone.

They can be found in the very far north of the Arctic -- the polar bear.

This male, like every polar bear, is almost completely covered in fur.

But his secret to staying warm in this frozen land is actually inside his large body.

He has a huge layer of insulating fat -- about four inches thick.

It traps heat, keeping him warm from the inside.

To maintain this fat, he relies on his good hunting skills.

His prey is hidden under the thick ice.

Luckily he has a secret weapon to help him hunt -- an extraordinary sense of smell, a hundred times stronger than ours.

♪♪ He can detect a seal carcass from around 20 miles away, and under three foot of snow.

Success.

He will eat all the fat of a seal first, often leaving the actual meat.

This extreme fatty diet would kill us, but for the polar bear, it's essential.

Indeed, they are one of the fattest mammals on Earth.

Their incredible insulation and intense sense of smell make the polar bear a master in the snow.

They're also built to move around effortlessly in this snowy environment, unlike me.

I am a perfect example of an animal that is not adapted for walking about a snowy environment like this.

I'm 12 stone, 12 and a half stone, and all of my weight is distributed onto my feet -- size 12 -- big feet for a human, but not big enough to stop me from sinking down into the snow.

What I need to do is increase that surface area -- put on some snowshoes.

I suppose the secret to moving around in deep snow is to do it efficiently.

Here we go -- adapted for walking in the snow.

That is so much better.

It's easy. I can walk through the forest.

I'm not sinking down in to my waist.

I can go fast.

I can almost go silently.

Like I belong here.

Polar bears have built-in snowshoes.

Their paws are wide, measuring up to 12 inches across.

This helps them to distribute their weight evenly on thin ice.

Underneath their large paws are small, soft bumps to give them extra grip on the ice.

As well as being superbly adapted to the snow, some bears have another strategy to get through winter -- by sleeping through it.

This is the recently vacated den of a brown bear.

The den would have been dug back in the autumn, 'round about October time.

In the hardest of winters, a brown bear will spend up to seven months in its den, not eating, not drinking, just drifting in and out of sleep, waiting for the thaw.

A bear will make a den which is just slightly bigger than itself -- a snug fit.

Some dens are built in rock crevices or hollow trees.

For others, like this polar bear, it can be simply a case of digging a small hole and then waiting for the snow to fall, providing an excellent, insulating roof.

♪♪ This female polar bear, filmed in captivity, is in hibernation.

During this time, her heart rate drops dramatically and she doesn't eat, drink, or urinate.

Amazingly, she's able to recycle waste into new protein to maintain her muscles.

Although she survives purely on fat reserves, she can, remarkably, give birth in hibernation.

Her body heat keeps her babies warm.

They grow rapidly thanks to her extremely fatty milk, which is nearly 10 times richer than human milk.

♪♪ I've spent much time filming polar bears and been lucky enough to see tiny twin cubs emerge from their winter den -- a truly wonderful sight.

Aww.

Aww, very, very cute.

They were very eager to explore the big, wide world.

After being born in hibernation, the family venture out when the babies are strong enough to survive outside and ready to make the trek to the spring sea ice.

Oh, wow.

Look at that.

It's a sight I will never forget.

Many smaller mammals also hibernate to avoid the bitter winter, but there is one which does so with a unique twist -- the Arctic ground squirrel.

When the harsh weather begins, the ground squirrel escapes to an underground burrow to hibernate.

Amazingly, the squirrel's body temperature drops to below freezing -- the lowest of any mammal.

His major organs shut down, and he looks dead to the world.

Despite this, he's able to stop himself from actually freezing to death.

Every few weeks, the squirrel begins to shake.

This shivering is enough to raise his body temperature back to up normal for a few hours.

After this session of shivering, he can safely cool back down, ready for another cycle of deep sleep.

For animals that don't hibernate, being well-insulated to withstand severe weather is essential.

For human beings in the cold, we have to layer up.

I've got five layers on. I've got gloves on.

We generate heat, and we want to retain that heat in sub-zero temperatures.

And if I remove my glove, it goes without saying my hands start losing heat, my hands start feeling cold, and you can see the comparison very clearly on the thermal camera between my cold hand and my warm hand.

The fingers on my cold hand are blue, showing how much heat they've already lost.

Animals are far more efficient than us at retaining heat.

And there is one animal which tops the lot.

The Arctic fox is superbly kitted out for the winter.

To prepare for it, he undergoes a spectacular transformation.

His thin brown summer coat changes into one which is 200% thicker.

It's white, and it's very, very fluffy.

Hello, you handsome, handsome boy.

My word.

That is the most sumptuous coat I have ever seen on any animal.

In fact, Arctic foxes have the warmest coat of all Arctic mammals.

And it's not just that fabulous fur the fox has got.

They have incredible senses -- particularly the hearing.

And despite having these fairly small ears, this fox will be able to detect his prey with pinpoint accuracy even when it's hidden underneath the snow.

In the depths of the Canadian winter, a young Arctic fox is searching for food.

He's still a hunting novice.

It's not easy when you can't see your prey.

With his acute senses, he can hear a faint sound under the snow.

[ Chirping ] Lemmings.

To catch one, he uses a special pouncing technique known as mousing.

He has to judge its exact distance as well as the depth of the snow.

To help them find the right spot, foxes actually align their pounce to the Earth's magnetic field -- an extraordinary skill.

[ High-pitched chirping ] But mousing isn't always easy, especially for a beginner.

♪♪ Super senses are crucial for animals that live in such white and snowy landscapes.

And I'm about to meet one whose eyesight is legendary.

This exquisite-looking cat is a lynx.

It's a cat that is especially adapted to the snow.

Look at those eyes.

Lynx have incredible vision.

It was once believed that lynx can see through walls.

And actually looking into those eyes, I find that quite easy to believe.

Maybe that's stretching it a bit, but a lynx can spot a mouse from 80 yards away.

And their night vision is truly remarkable, far better than ours.

At this time of year, when the landscape is dominated in snow, you can see how easily the lynx just disappears in it -- matches these birch trees.

It's almost invisible.

That's all the lynx needs is a little bit of something to break up its outline.

In the wild, lynx are incredibly difficult to glimpse.

They roam the remote forests for hundreds of miles in search of prey and may never visit the same patch twice.

With so few prey animals here, life for this silent hunter is particularly hard.

And in this harsh wilderness, they're not the only hunters.

The great gray owl waits and listens.

He's watching for prey.

He has excellent, super-sensitive hearing.

He can even hear the scuttling of voles or mice beneath two foot of snow.

He glides silently, like a king of acoustic stealth.

His wings absorb any noise of flapping so he can take his prey by complete surprise.

[ Mouse squeaks ] To survive in a snowy landscape, it helps to have a secret advantage, a trump card up your sleeve.

My next snow animal has quite a surprising one.

Reindeer traditionally pull sleighs and have a popular reputation for red, glowing noses.

But behind this folklore, there is some surprising truth -- an ingenious adaptation which helps them survive the extremes.

Their noses are full of blood vessels.

These cool warm air down as it leaves the body and warms cold air up as it comes in, keeping the reindeer's brain constantly warm and active.

So, as the thermal camera proves, reindeers' noses are actually red.

It's not just the nose of the reindeer which is extraordinary.

How they view their winter surroundings, through those large, characterful eyes, is truly astonishing.

When it's bright and sunny like this, my eyes struggle to cope with the amount of UV light that's coming from the sun and is bouncing back up off the snow.

If I was to spend too long here, I'd eventually damage my eyes.

I could become snow blind.

But reindeer, they see things differently.

Not only can they see in color like I can, they can also see in ultraviolet.

For us, it's difficult to make out detail when the landscape is so white.

But with UV vision, a reindeer can see things in much greater contrast.

They can see shapes and detail that we can't.

The lichen on the trees which they eat or animal urine in the snow becomes more prominent.

In such a white, snowy world, it certainly helps to have that extra insight.

Reindeer even have specially designed, flexible hooves.

In the winter, their four toes can spread out wide to act like snowshoes.

This means they can walk on bumpy ice without slipping.

However, on smooth ice they can sometimes find their shoes a little ill-suited.

♪♪ When it comes to surviving against all the odds, there is one snow animal which has to endure one of the most extreme places on Earth.

From the top of the world to the very bottom is Antarctica, the coldest, windiest, and driest continent on the planet.

This desolate freezer is also the chosen home of the penguin.

[ Penguins calling ] How do they survive in minus-90 degrees Fahrenheit?

Well, penguins are superbly built to resist the extreme cold.

First of all, their round, shapely figure isn't by accident.

It provides them with enough blubber to keep warm.

But how do penguins manage to keep their extremities like wings and feet warm?

Well, their bodies are cleverly adapted so that the muscles needed to move their feet and wings are kept inside their warm, round body.

Only tendons operate within the actual limbs, and these are far less vulnerable to the cold.

But it doesn't stop there.

These ice specialists have another clever trick to keep warm.

To reduce the amount of body touching the frozen ground, they just lean back on their heels, picking their toes off the ice.

It can decrease their heat loss by 15%. Penguins may not be able to fly, but they do have a lot of feathers.

And it's thought that penguins have more insulating feathers than any other bird.

And I've got some here.

Just look at them.

These are from an emperor penguin, a species that has to endure bitterly cold Antarctic conditions.

And it is a masterpiece.

At the base, it's incredibly downy and fluffy.

The quill part is stiff.

The end is slick.

This is the waterproof part.

And on the bird, these feathers interlock.

The outside is waterproof.

It creates a waterproof seal.

Underneath is an air void full of these downy feathers.

This is an incredibly sophisticated form of insulation.

Penguins are understandably very protective of their precious feathers.

So much so, that when the males come together to form their famous huddle, they take extra-special care not to damage them.

In the deepest part of the Antarctic winter, the male emperor penguins are huddling together to try and keep themselves, and their eggs, warm.

The center of the huddle is the hottest part.

It can even get too hot.

So the penguins constantly move around, changing their position.

But instead of pressing into one another, they are barely touching.

If they were squashed together, the insulation from their incredible feathers would be compromised.

So they leave almost an inch gap between each other to protect their feathers.

This means that if one penguin moves, its neighbor has to react and follow suit.

Just one penguin's step creates a chain reaction, sending a ripple of movement throughout the huddle.

There is only one mammal which is tough enough to live this far south in the Antarctic all year-round, and that's the Weddell seal.

This incredible snow animal spends much of its life under the expanse of the frozen sea ice.

The Antarctic Ocean can drop to 28 degrees.

Weddell seals can only survive about an hour under the freezing water before needing air.

They have to find a natural crack in the ice to create a breathing hole.

To do this, they have a unique adaptation.

A sharp tool designed especially for the job -- large, very strong, protruding teeth.

With these razor-sharp incisors, a seal is able to scrape away fresh ice and keep the hole open.

♪♪ But these breathing holes also serve another function.

The males attract females to them during the mating season.

One male can draw up to 10 females, so the holes are hotly contested.

This Weddell seal male is on the search for one.

It's not easy in the gloom under the ice, but it's thought that seals may use their acute hearing and sense of touch through their whiskers to help them.

His call can be heard by other seals nearly two miles away.

[ Seal calling ] He's found a hole, but another male has beaten him to it.

Let battle commence.

The occupant is just too strong for him.

For now, he'll just have to move on and hope his luck will improve elsewhere.

♪♪ In the far northern coast waters, most birds have migrated for the winter.

But one species of bird braves the icy seas -- eider ducks.

Hundreds of thousands of them.

This patch of water is their last refuge.

These open pools are kept free of ice by strong currents underneath.

From here, the birds can dive down into the water, picking off mussels from the depths of the sea.

Surrounded by ice, the eiders' survival depends on this single, vulnerable oasis, and conditions here can change very fast.

In a smaller pool, other eider ducks are learning a bitter lesson.

An early winter storm has caught them out, and the ice is closing in.

The pool is shrinking, and the ducks are perishing.

The larger pool has a far greater chance of staying open all winter, and the ducks will have avoided an exhausting migration.

It's always a gamble, but for these ducks, one which should pay off.

As the winter progresses, temperatures plummet and snow can sometimes fall for hours at a time.

Snow forms when water vapor in the atmosphere freezes into ice crystals.

The ice crystals become snowflakes as they fall to the ground, each one intricate and unique.

Although snow appears white, it's actually colorless but reflects the light from the sun.

Falling snow looks beautiful to us, but it can be deadly.

As the snow gets deeper and deeper, animals need to be even more specialized to cope.

When it comes to being prepared for the coldest part of the winter, these musk ox certainly look ready.

That long, thick, shaggy coat is so efficient a musk ox only uses a small amount of energy to keep warm.

They can even slow down their metabolism so that in the wintertime, they require less food.

And to get to that food, their front hooves are bigger than their rear hooves to dig down through the deep snow to get to the food.

And if the snow is very, very deep, they can use their big head and massive neck muscles.

They can excavate the snow to get right down there to the vegetation beneath.

Musk ox look like an animal that has been especially designed for the cold.

These hairy, prehistoric-looking creatures have inhabited the Arctic for thousands of years.

They roam on the Arctic tundra in search of roots and mosses that sustain them.

They live in herds and can withstand incredibly harsh Arctic winters.

In the American Rockies, there's another snow animal with a very similar hardy physique -- bison.

Yellowstone is a unique place.

A quirk of geology has created thousands of thermals and geysers.

But it's not for the feeble.

For half the year, Yellowstone is frozen.

Temperatures can reach minus-50, and the winter snow can be more than 20 foot deep.

Just as well these bison are built for the snow.

However, they are struggling in what is the snowiest winter here for a decade.

They're able to swing their massive heads through the snow, but this year it's so deep they can't reach the grass underneath.

A bison's amazing, thick coat keeps it warm down to about minus-22.

But the wind chill is now pushing them to that limit.

They need to move.

That will take more energy.

It's a risk that they will have to take.

The herd need to find somewhere warmer to survive.

They follow an ancient route where hot thermals have kept the river running.

It should lead to a place they can eat and rest.

It's a long, hard trek.

The bison have to keep to moving.

They just can't afford to stop.

In such a tough landscape, not every bison will survive.

The herd have finally reached their destination.

It's an oasis.

Thermals have melted the snow, and grass is abundant.

It's a huge relief.

The bison can fill their empty stomachs at last.

But not all is rosy in paradise.

Due to the volcanic waters and geysers, the grass here is laced with arsenic which could, over time, slowly poison the bison.

The herd know they can't stay too long.

However for the moment, it offers them a lifeline from the unrelenting snow.

♪♪ Food can be incredibly hard to find in a landscape like this.

The rivers and the lakes are completely frozen.

The snow underfoot is incredibly deep.

So animals have to use every trick in the book, every ounce of their intelligence just to stay alive.

A family of otters is making its way to a river kept open thanks to the underwater geysers.

Here, they can happily fish for a much-needed dinner.

♪♪ However, they are not alone in this snowy landscape.

They are being spied on by a clever trickster -- a coyote.

He's been watching and waiting as the otters dive for fish.

This otter doesn't want to risk losing his dinner and plans to hide his catch under the ice.

Although the coyote can't see the otter, he can hear him moving somewhere underneath him.

The otter emerges but without the fish.

He's stashed it somewhere under the ice, but where?

It's turned into a game of hide-and-seek, and the coyote fancies his chances.

♪♪ A huge trout -- what a prize.

In these conditions, being cunning as well as a little bit devious can be the key to survival.

Beneath the blanket of snow is another game of hide-and-seek... ...one which is a matter of life and death.

This little vole is active throughout the winter.

He travels along tiny corridors, moving from pocket to pocket of perfectly refrigerated food.

Snow is a great insulator, so down here the temperature never falls more than a degree or so below freezing -- warm enough for the vole to thrive.

But he's not the only one out here.

A least weasel is also about.

♪♪ He may look cute and friendly, but he has a devious plan.

His body is exactly the same width as the vole's, so there's nowhere the vole can go that the weasel can't follow.

The weasel's long, slender shape is perfect for hunting in the tunnels, but the worst possible shape for staying warm.

So to solve this problem, he has a solution -- though not a good one for the vole.

The weasel plucks the fur from the vole's body tuft by tuft.

Then, putting it all together, he cleverly makes a warm blanket.

A sad end for the vole, but a warm, underground bed for the cold-hearted weasel.

It's everyone for themselves in this climate.

We've seen some amazing strategies for surviving the cold.

But there are other creatures battling to stay alive, things we don't even see.

Underneath the snow, they are thousands of insects having their own battle with winter.

And bizarrely, for some of them, their survival strategy is being frozen alive.

♪♪ One of the most remarkable is a small Arctic caterpillar known as a woolly bear.

He spends his winter curled up under a rock.

As the temperature drops, he goes into a kind of coma, his heart stops beating, and his insides completely freeze.

He remains frozen like this for four months.

Then, when the Arctic spring arrives, he thaws out, as if rising from the dead.

This furry little critter eats as much as he possibly can before the cold closes in once again.

♪♪ And so it goes on.

Year after year, he slows right down and freezes solid to survive winter after winter.

The feeding season in the Arctic is so short, it can take years for the caterpillar to complete its growth.

But eventually that time comes.

The caterpillar frantically starts to weave a beautiful silk cocoon.

Meanwhile, inside, his body starts to change into one that can fly.

Now, the oldest caterpillar in the world is ready to fulfill his life's purpose.

He has just days to find a partner and mate so he can help create the next generation of wonderful woolly bears.

He may be tiny and hidden away, but this little caterpillar has one of the most extraordinary ways to survive the big freeze.

[ Wolves howling ] We've seen how some remarkable animals can adapt to their surroundings.

These are animals that not only live, but thrive, in some of the coldest, most inhospitable places on Earth.

Whether it's their super senses, their extraordinary physical adaptations.

or whether it's just clever tactics, these animals are a thing of great wonder.

And for me, these animals are not only the most impressive creatures on the planet, they're some of the most beautiful.

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