♪♪ [ Suspenseful music plays ] NARRATOR: In the uppermost reaches of North America... ...there's a big, wild country -- Canada.

It has the largest intact forest on Earth.

More than two million rivers, lakes, and streams.

[ Tweeting ] Vast swathes of tundra.

[ Grumbling ] And endless rugged shores.

It can be a punishing place to live.

But it's also a land of opportunity... [ Squawk ] ...with riches for the taking.

[ Chirping ] Knowing how and when to act makes the difference between life and death.

Get it right, and Canada can be a place to thrive.

♪♪ ♪♪ NARRATOR: Hudson Bay, on the edge of the Arctic Circle.

[ Buzzing ] Home to Canada's most iconic marine mammal... ...the polar bear.

[ Suspenseful music plays ] ♪♪ It's summer and the days are long; the air, warm.

This is the hardest time of year for these big predators.

[ Grumble ] There's no sea ice to hunt from... ...and the land offers little to eat.

♪♪ [ Bird chirping ] The polar bears are losing more than two pounds of fat every day.

♪♪ They're hungry.

♪♪ But polar bears have good memories.

♪♪ These hunters are heading for a river mouth where they know they can find food.

♪♪ [ Grumble ] And they've got their timing just right.

♪♪ Beluga whales are arriving... [ Squeaking ] ...by the thousands.

♪♪ They're here to raise their young in the warm, shallow waters of the estuary.

♪♪ ♪♪ But it's not without risk.

♪♪ These two males are eager to hunt.

[ Grumble ] [ Grumble ] But they have very different approaches.

One bear bides his time on a carefully chosen rock.

[ Whimsical tune plays ] While the other goes after the belugas.

♪♪ ♪♪ ♪♪ In the open water, the belugas are impossible to catch.

♪♪ His tactic clearly isn't working.

♪♪ There's a trick to this... ...and it's all down to the tides.

[ Suspenseful music plays ] As the waters rise, the belugas come farther in shore.

Better for the polar bears.

♪♪ As long as the swimmer doesn't give the game away.

[ Huffing ] ♪♪ The patient bear's rock is now submerged.

But he still has a chance.

♪♪ ♪♪ Experience has taught this old-timer how to be an efficient hunter.

♪♪ The other bear still has a lot to learn.

♪♪ The belugas won't stay here for long... ...so, the polar bears must feed as much as they can in this narrow time window.

♪♪ And, with bellies full, there's even a bit of time for play.

[ Grumble ] [ Grumbling ] ♪♪ Canada is a vast land mass covering nearly four million square miles of North America... ...and half of it is treeless tundra, rugged and exposed.

To survive here, you need to be smart... ...like the arctic fox.

This male has caught a lemming for his mate.

She needs his help... [ Whimsical tune plays ] ...as she's got young to look after.

♪♪ FOX: [ Squeak ] KITS: [ Squeaking ] NARRATOR: Both parents have a lot on their plate... ...raising six boisterous kits with big appetites.

♪♪ ♪♪ [ Squeaking ] [ Suspenseful music plays ] On top of that, the parents must gather enough food to help them through the winter.

[ Wind whipping ] Luckily, there's a big opportunity heading their way... [ Honking ] ...snow geese.

[ Whimsical tune plays ] Every summer, thousands of them come here to raise their young.

♪♪ ♪♪ Each mother goose lays a clutch of eggs, which she'll sit on for three weeks.

These eggs are what the foxes are after.

[ Honking ] They want to gather as many as they can before they hatch.

[ Honking ] [ Honking ] It's not easy getting past the feisty parents.

[ Honking ] But the foxes are determined, and gather up to 60 eggs a day.

Each one they steal, they bury in the frozen earth.

It's a great way to store food, as it'll keep for the leaner months ahead.

[ Honking ] [ Honking ] Once the hatching starts, there's another opportunity for the foxes... ...just as the kits are ready for solid food.

[ Squeaking ] [ Tranquil tune plays ] But it doesn't last long.

[ Chirping ] Within hours of hatching, the goslings are led to the safety of water.

♪♪ Most of the snow geese will make it through the summer, until it's time to journey south.

♪♪ Though the foxes can't leave, they're well-prepared for the tougher times ahead.

Mom even scavenges the biggest feast of all.

♪♪ The family is fed; and the larder, full.

♪♪ ♪♪ [ Wind whipping ] Opportunities in Canada's wild north can be immense... ...but the windows are often short and require precision timing.

[ Thunder rumbling ] [ Suspenseful music plays ] Nova Scotia, on the East Coast, has the most extreme tides on Earth.

Here, in the Bay of Fundy, 176 billion tons of water moves in and out twice a day.

That's more than the combined flow of all the world's rivers.

Living in these mudflats are creatures that only come to the surface in late summer.

♪♪ [ Squelching ] Mud shrimps.

Out looking for mates.

But up here, the pursuit of the opposite sex leaves them very exposed... ♪♪ ...to an annual onslaught.

Semipalmated sandpipers.

[ Chirping ] Two hundred thousand of them.

These birds are on a huge migration from Canada's arctic to South America.

♪♪ They stop here to feast on the shrimps.

And they can't move on until they've doubled in weight.

Each small bird must harvest up to 20,000 shrimp.

In a single tidal cycle.

But as the incoming tide pushes the sandpipers back up the beach, they have less room for maneuver.

Easy targets for a deadly predator.

♪♪ ♪♪ The peregrine falcon.

The fastest creature on Earth.

♪♪ ♪♪ The flock moves as one, trying to confuse the hunter.

♪♪ ♪♪ They dodge the first strike.

But their nemesis gains height for an even faster attack.

♪♪ ♪♪ A weak one is injured.

[ Chirping rapidly ] And taken.

[ Melancholy tune plays ] The peregrine is a constant menace.

But after 10 days of good feeding, the sandpipers have put on enough weight to continue their epic journey south.

♪♪ Canada has the longest coastline of any country on Earth -- more than 150,000 miles.

And, on its western margins... [ Ethereal tune plays ] ...where the land meets the Pacific Ocean... ...there's a magical world nourished by cool, rich water.

♪♪ ♪♪ Along the coastline of British Columbia are giant forests of kelp.

This algal seaweed can grow up to two feet a day... ...its special air sacs lifting it towards the summer sunshine.

♪♪ ♪♪ Sea otters are well-adapted to this aquatic forest.

They tether themselves to the kelp, as it allows them to snooze without drifting away.

[ Squeaking ] These social animals float together in rafts up to 100 strong.

[ Romantic tune plays ] Summer is peak pupping season.

♪♪ ♪♪ To keep their babies warm, the mothers balance them on their tummies... ...and blow air into their thick fur.

[ Blowing ] ♪♪ Sea otters burn so many calories in these chilly waters, they need to eat three times more food than similar-sized land mammals.

This male is on the hunt for the ultimate meal.

Finding it is one thing.

Extracting it is another.

It's more than three feet under the sand.

And the air in his fur is constantly pulling him upwards.

A geoduck -- one of the world's largest burrowing clams.

[ Creatures quacking ] Sea otters stick together for safety.

And, here in Canada, they need to stay alert... [ Suspenseful music plays ] [ Calling ] ...for on these shores stalks an age-old enemy.

♪♪ The sea wolf -- a specialist coastal hunter.

[ Bird cawing ] ♪♪ ♪♪ But this pack isn't looking for otters today.

[ Bleating ] ♪♪ There's a far bigger opportunity coming their way.

♪♪ Pacific salmon, great shoals of them.

These pink salmon are one of the five species arriving on the West Coast of Canada.

After years of feeding at sea, they're in their prime and ready to migrate inland to spawn.

But they need conditions to be just right before they swim upriver.

[ Cawing ] And, while the salmon wait, they're easy targets for the wolves.

There's more than enough to choose from.

[ Bird cawing ] Each wolf can catch up to 30 salmon an hour.

But there's a problem with these fish.

The salmon's flesh is riddled with parasites, which could be lethal for the wolves.

Yet they keep on hunting.

[ Cawing ] [ Cawing ] These wolves have a strategy.

[ Cawing ] They lay the salmon out... ...letting the scavengers come and feed.

[ Cawing ] Birds, like crows and bald eagles are able to eat the flesh because they're unaffected by the parasites.

The wolves are left with the nutritious skin and head, which they can eat safely.

This partnership is a clever solution.

Everyone benefits from this seasonal bounty.

[ Thunder rumbles ] [ Cawing ] [ Ethereal tune plays ] ♪♪ As autumn sets in across British Columbia, more and more rain falls... ...causing rivers to rise.

The salmon are ready to begin their marathon journey upriver.

♪♪ ♪♪ ♪♪ ♪♪ ♪♪ Traveling hundreds of miles inland is a huge feat of endurance.

But the salmon finally reach their spawning grounds.

♪♪ They pair up and lay thousands of eggs.

♪♪ Only 10% will go on to hatch.

The rest are an important source of food for creatures like the dipper.

[ Chirping ] In Canada's wild north... ...the sea nourishes life far inland.

♪♪ ♪♪ Spawning is the salmon's final act.

♪♪ Black bears take the salmon, dead or alive.

They need to double in weight before hibernation.

♪♪ ♪♪ The bears also carry some salmon into the forest.

[ Birds chirping, insects buzzing ] Often, more than they can manage.

♪♪ [ Bird cawing ] But they're not wasted.

Their rotting bodies help feed the earth... ...allowing the trees along these riverbanks to grow 30% faster.

♪♪ This forest is called the Great Bear Rainforest... ...but it's the salmon that make it great.

[ Chirp ] ♪♪ As the seasons progress and the days shorten... ...the big windows of opportunity are starting to close.

[ Wind howling ] [ Bird cawing ] Canada is bracing itself for what's to come.

And there are few environments tougher than the great boreal forest that stretches right across Canada, from the Yukon in the west to Newfoundland in the east.

Over a million square miles of it.

The largest intact forest on the planet.

♪♪ ♪♪ As winter sets in, opportunities are slim.

[ Bleating ] Yet taking them means the difference between life and death.

[ Birds cawing ] ♪♪ Here, in the Yukon, there are no great migrations arriving... ...no windfall of food.

Just relentless cold and snow.

It'll be like this for months.

Snow changes the whole dynamic of the landscape.

[ Clinking ] Its texture is constantly changing with the air temperature and moisture levels.

[ Wind whipping ] [ Bird cawing ] Today, it's firm.

[ Creaking ] Ideal conditions for a stealthy hunter.

[ Footsteps crunching snow ] A cat whose paws are so perfectly shaped, it can walk in almost total silence.

The Canada lynx.

[ Bird cawing ] And this is what he's after.

A snowshoe hare.

To stand a chance of catching it... ...he must get within 30 feet.

[ Suspenseful music plays ] ♪♪ ♪♪ [ Sniffing ] [ Bird cawing ] The hare is brilliantly camouflaged, with acute hearing, sensitive whiskers... [ Sniffing ] and a wide field of view.

♪♪ [ Bird cawing ] ♪♪ ♪♪ [ Sniffing ] [ Sniffing ] [ Creaking ] [ Sniffing ] ♪♪ ♪♪ ♪♪ [ Branch snaps ] [ Hare squeals ] [ Bird cawing ] The Canada lynx is dependent on snowshoe hares.

When hare numbers are down, lynx struggle.

And when they are up, the lynx really prosper.

[ Bird cawing ] Canada's wild north is a land of boom and bust and this year is a good year.

[ Ethereal tune plays ] This family, with four healthy kittens, is testament to that.

♪♪ ♪♪ The boreal forest may seem sparse and empty... ...but there is plenty of food here, if you know where to look.

[ Creature calling ] Much of it is concealed in a secret world beneath the surface of the snow.

[ Whimsical tune plays ] Meet the red-backed vole.

He uses his network of tunnels to find his food, such as bark, seeds, and berries.

♪♪ But there's one creature that can hear his every move.

[ Suspenseful music plays ] The great grey owl.

She's the largest of her kind in the world.

With a big appetite for voles.

♪♪ The circle of feathers around her eyes directs the faintest sounds to her ears.

♪♪ Under the snow, the vole is as quiet as possible.

[ Sniffing ] [ Sniffing ] [ Bird cawing ] But it's not his lucky day.

A short-tailed weasel has picked up his scent.

He's got to get out.

♪♪ ♪♪ ♪♪ ♪♪ ♪♪ His tiny footsteps are a beacon to this silent killer.

♪♪ ♪♪ [ Squeak ] This time, the owl misses her chance.

[ Sniffing ] The vole gets to live another day.

[ Ethereal tune plays ] ♪♪ At night, Canada's boreal forest becomes a very different world.

♪♪ Temperatures plunge to -40° Fahrenheit.

Surely, not the best time to be out foraging.

But there is an unusual creature who is.

[ Rustling ] A type of squirrel.

Because it's so cold, she can't stay out for long.

[ Munching ] That means she needs to find food, fast.

To achieve this, she's got a special trick.

This is a southern flying squirrel.

Gliding helps her get around quickly and minimizes her exposure to the cold.

[ Suspenseful-whimsical tune plays ] Time is up for tonight.

♪♪ This tree nest provides some shelter... [ Sniffing ] ...but it's still incredibly cold inside.

♪♪ Fortunately, someone else has arrived.

[ Romantic tune plays ] [ Sniffing ] ♪♪ That's a bit warmer.

♪♪ Two is good company, but here, everyone is welcome.

♪♪ ♪♪ Many unrelated individuals share the same nest.

♪♪ Cuddles enough to get them through the night.

♪♪ [ Wind whipping ] Among the great stands of Canada's boreal forest, hidden beneath the snow, are 600,000 icy lakes.

These big, open spaces can make all the difference in the constant battles between two ancient enemies.

Canada wolves are very smart and adaptable hunters.

[ Howling ] They know how to make the most of this environment during winter, and use it to their advantage.

[ Howling ] One of their favorite prey is caribou.

They find strength in numbers and are often on the move, looking for food.

[ Howls ] The wolves constantly shadow them, waiting for any opportunity.

[ Grumbling ] Out on the frozen lakes, where the ground is firm underfoot, the caribou have the advantage, as they can outrun the wolves.

The hunters are beaten.

For now.

[ Howling ] It becomes a waiting game.

[ Suspenseful music plays ] ♪♪ But the wolves know the caribou can't stay here forever.

♪♪ The caribou need to eat... ...and the only place they can find food is in the forest, on the edge of the lake... ...where the snow is a lot deeper.

♪♪ ♪♪ In this difficult terrain, the caribou are far more vulnerable.

♪♪ They must work fast... ...digging for lichens... ...and keep on high alert.

♪♪ [ Bird cawing ] ♪♪ The wolves are coming.

♪♪ ♪♪ Using the forest as cover... ...they edge ever closer.

♪♪ Until they've surrounded the herd.

♪♪ [ Grumbling ] ♪♪ The wolves need to keep the caribou in the deep snow... ...without getting stuck themselves.

♪♪ ♪♪ One trip is all it takes.

[ Grumbling ] By keeping numbers in check and removing the sick and the weak, the wolves actually help the caribou herds stay healthy.

[ Grumbling ] This is a vital meal for them, and a relatively small loss for the caribou.

[ Ethereal tune plays ] ♪♪ By February, the days are getting longer and winter is easing back.

These days, it rarely lasts as long as it used to.

Here in the Gulf of St. Lawrence, the sea ice is already beginning to break.

[ Rumbling ] ♪♪ But it should remain for another six weeks.

This is a vitally important breeding platform for one of Canada's most prolific marine mammals.

The harp seal.

Adults spend most of their lives out at sea... ...but return to the ice sheets each year to give birth.

Almost 200,000 pups are born here every year.

[ Honking ] [ Squeaking ] And they need to become independent before the sea ice disappears.

[ Calling ] [ Squeaking ] [ Honking ] [ Squeaking ] Luckily, baby harp seals are fast growers.

By constantly suckling his mother's fat-rich milk, this pup can put on five pounds a day.

His mother is dedicated.

She won't leave him to feed herself until he's fully weaned.

But she can only keep this up for two weeks.

Fortunately, she's on track.

It's day 10 and he's already tripled in size.

♪♪ [ Squeaking ] ♪♪ His impressive new layer of blubber is about to be put to the ultimate test... [ Calling ] ...his first swimming lesson.

♪♪ ♪♪ It's vital he learns these skills before the sea ice melts.

♪♪ ♪♪ He seems very reluctant.

But Mom encourages him in.

♪♪ ♪♪ Finally, he's made it.

♪♪ ♪♪ He seems very much at home in this big, new world.

♪♪ His mother's work is done.

He'll stay close to the safety of the ice for as long as it stays frozen, before he takes to the water for good.

♪♪ Canada's coastline will be his to explore.

♪♪ Right across this vast country, spring is gathering momentum.

The snow and ice are melting fast... ...giving way to a whole new world.

♪♪ A land of green and blue.

♪♪ Thousands of lakes are revealed.

♪♪ And windows of opportunity are opening up for all kinds of creatures.

♪♪ [ Buzzing ] ♪♪ ♪♪ Canada is a land of extremes.

♪♪ [ Thunder crashes ] For the wild residents who call this home, life and death go hand-in-hand.

[ Squeaking ] [ Growl ] But they all learn to adapt... ...survive, and even prosper... ...by seizing the opportunities that nature provides... ...in Canada's wild north.

♪♪ ♪♪ ♪♪ ♪♪ ♪♪ To learn more about what you've seen on this "Nature" program, visit pbs.org.

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