Narrator: In Norse myth, there are tales of a mighty sacred tree, Yggdrasil, connecting the realms of gods, giants, and humans.

Great forests are still at the heart of Scandinavia, stretching towards the Arctic and cut through with a maze of waterways... [Splash] ever-changing through the seasons, from the chilling grip of deep winter to the warm riches of Summer.

This enchanted wilderness is home to mysterious creatures who survive through surprising and ancient alliances.

[Birds cawing] Scandinavia is a land steeped in myth... of Thor and Odin... from Norway's frozen wilderness... [Grunts] deep into magical Swedish woodlands... across Finland's waterworld to explosive Icelandic volcanoes.

[Explosion] [Waves crashing] These breathtaking landscapes have shaped its people... [Skate blades scrape on ice] ♪ and its wildlife.

♪ Bound together by a resilient spirit, they each face unique challenges in wild Scandinavia.

[Splash] [Bird calls] In the heartlands, 160 billion trees thrive in this northernmost woodland... ♪ part of the vast boreal forest that fringes the Arctic.

Here, bowed spruce stand like ice giants of Norse legend... enduring a winter of 5 long months.

They wear a coat of tykky, layers of ice crystals grown from the freezing moist air... and they're highly adapted to these extremes.

Flexible branches carry the heavy, insulating snow... while within, natural antifreeze protects their tissues.

These fairytale trees are masters of resilience... but all who live here must find their own way to survive the tough winter.

Clever tricks and partnerships work for some.

[Birds squawking] ♪ Ravens were said to be informants to the Norse God Odin.

They scoured the world for gossip to bring back to their master.

[Ravens squawking] But for these vocal birds, food is the only topic of conversation.

[Ravens continue squawking] And word has spread fast, drawing in a crowd.

With the carcass frozen, they can't break in... [Squawking] but their commotion attracts just who they need... a golden eagle... [Screech] Scandinavia's most powerful raptor.

[Squawking] It knows that where there are ravens, there's food.

♪ 6 times their size, an eagle can easily kill a raven... [Squawking] but there are benefits to inviting your adversary to dinner.

The eagle has the tools to open up the carcass for them, if only they can sneak back to the table.

♪ ♪ [Squawking] But their dinner plans are cut short.

More eagles arrive to claim their share of this feast.

All the ravens can do is watch as these titans battle it out.

♪ ♪ Eventually, a new victor emerges.

[Raven squawks] It's able to eat its fill undisturbed... and finally allows the ravens back to the opened carcass.

[Squawking] This fleeting alliance of brains and brawn benefits them all.

♪ Some relationships here are so deeply entwined, it's hard to imagine one without the other.

♪ Margret Fjellstrom is an indigenous Sami reindeer herder.

Her family have depended on the reindeer for generations.

Fjellstrom: The reindeer provide me food, it provides clothes, but it's also provides me, uh, contact with nature, with my ancestors, and my future.

It's who I am.

[Bell clanging softly] Narrator: Margret must keep her herds alive through harsh winters, where temperatures can plummet close to -40.

It's essential the reindeer get energy-rich food... particularly the pregnant females.

And to find it, they must seek out the heartland's oldest forests.

[Starts engine] Margret and her family use snowmobiles, steering the herds up to 30 miles a day to the best grazing spots.

Fjellstrom: Whoo!

[Calling in native language] [Bells clanging softly] Whoo!

Whoo!

Narrator: The reindeer need help from the Sami, as their traditional migration routes are often blocked by roads, towns, and wind farms.

Fjellstrom: The infrastructure of the land have changed, so we need to guide the reindeers around and find safe places for them.

Whoo!

Whoo!

Narrator: On their journey, the herds pass through new-growth plantations... but these areas have little nutritious food to offer them.

It's the forests with trees over 100 years old that have what they desperately need... lichen.

During the winters, they make up 80% of the reindeer's diet.

♪ They eat a dozen different varieties.

♪ With their excellent sense of smell, reindeer can detect them 3 feet beneath the snow.

♪ Lichens may look like plants, but they're actually an ancient partnership between algae and fungi.

And as many grow just a fraction of an inch a year, it takes decades for lichen-rich forests to develop.

But now, they are becoming more scarce.

Fjellstrom: I see this forest, it was all over, and it was thick layer of lichens.

You know, it was to like to walk on soft, soft cotton.

But lichen is burned by the Sun.

Narrator: More than 70% of Sweden's age-old woodlands have been cleared in the last 60 years, threatening the balance that sustains the Sami way of life.

Fjellstrom: Now we're using the forest faster than the forest can provide and grow up.

That's the problem, because if the lichen forest is disappearing, the reindeer will starve to death.

[Flames crackling] Narrator: Some winters are more challenging than others... but when Margret's reindeer reach the food they need, it makes it all worthwhile.

Fjellstrom: When I see the reindeer is grazing outside and it's good condition, it's like a big love story.

You get all tickly in your body and you're smiling.

It's the best feeling.

You know, when you're in love, really love, that's the feeling.

Narrator: Margret has always had a special relationship with the reindeer, and together, they'll continue to endure the challenges of this ever-changing landscape.

[Fjellstrom shouting in distance] As the days become longer, winter begins to loosen its stranglehold... but within the forest, this boggy clearing is still frozen and carpeted with snow.

Every April, it becomes the focal point of one of Scandinavia's most flamboyant wildlife spectacles.

[Birds calling] As dawn breaks, a distinctive bubbling sound carries through the air... war cries of male black grouse.

♪ They're here to compete for mating rights to the mottled brown females.

On this battleground, known as a lek, there's a distinct hierarchy.

And in the center of it all is the king.

He's the champion fighter flaunting the biggest scarlet eye combs... and finest lyre tail feathers.

Popular with the hens, he wins the most mates... but every male wants his success.

Threats come from all sides.

[Squawking] Novice males are just learning the ropes... [Bubbling call] and are easily intimidated.

But there's one battle-scarred male who's a serious challenger.

[Screeching] This old-timer has sacrificed many of his fine feathers in combat... and isn't satisfied with a place on the edge of the action, watching the hens pass him by.

He challenges the king to a duel.

Both are heavyweights at over 4 pounds and closely matched.

♪ The old-timer rips out a clump of chest feathers.

♪ The king retaliates.

♪ The battle goes on for almost an hour.

♪ Both sustain stabbing injuries to their chests... ♪ until the king deals the final blow.

[Squawking] Injured, the old-timer is defeated.

The king grouse retains his title and is eager to make good on his victory.

His reward?

To mate with over half the females on this lek... as the snow begins to thaw, exposing the peaty bog once more.

Across Scandinavia's heartlands, spring heralds a time of magnificent transformation... [Water flowing] the great melt.

[Splashing] Water is liberated from the mountains... into fast-flowing rivers and streams.

Some of the world's most spectacular waterfalls are found in Scandinavia... cascading through the landscape... and filling hundreds of thousands of lakes carved from rock during the last ice age.

[Birds calling] For Swedes, Varkanslor, or spring fever, begins with returning migrant birds.

[Moose grunting] Moose are also on the move, following long-standing migration routes towards new pastures.

♪ In the forest canopy, warmer days trigger the pinecones of Norway spruce to ease open.

[Crackling] Just one tree can release tens of thousands of seeds every year.

but only a few will survive to join the heartland's giants, standing up to 130 feet tall and living for 600 years.

Over half of Scandinavia is covered with trees, and ideas of the forest have always been entwined in Norse folklore, fabled to harbor many mythical creatures.

There are tales of trolls, murderous giants, and dangerous seductresses.

One forest animal was renowned as the companion of Freyja, goddess of love... the lynx.

It's Europe's biggest and most elusive wildcat... [Barking scream] but his scream isn't as sinister as it sounds.

[Barking scream] It's the mating season, and this roving bachelor is looking for love.

[Barking scream] He searches for special trees that could help with his quest.

He rubs his body all over the scaly trunk of this Scots pine... releasing odor from glands on his cheeks and paws... a love letter to receptive females and a warning to other males.

His signature is etched into the bark and sealed with his scent.

The textured surface will preserve his smell for weeks and even snags a lock of his fur.

♪ He continues his patrol... leaving fragrant messages on distinctive landmarks.

Lynx travel up to 30 miles each day.

Over 3,000 of these rare cats wander the heartlands of Scandinavia.

[Growl] Hopefully, a female will hear or smell him as he roams his vast territory, over 300 square miles... weaving through forests increasingly fragmented by human expansion.

[Chirping] During spring, the weather is still changeable.

A passing storm brings fresh snowfall.

[Paws crunching in snow] ♪ And there's a glimmer of hope.

A beautiful female lynx has taken a keen interest in the male's aroma preserved in the tree's craggy bark.

She's smaller than him with lighter fur and sprays her own calling card as a reply.

It can take a lynx 2 weeks to patrol his territory... but this male returns to some good news.

[Growling] The female's lingering perfume reveals she was here recently and she's in season... much to his delight.

With the help of this distinctive gnarled tree, this lynx has finally had his love letter answered... [Spraying] and hopefully his chance to meet her face-to-face is just 'round the corner.

♪ Every creature here relies on the forest, and by late spring, it is lush... and green.

[Grunting softly] After the long winter, this female brown bear finally emerges from hibernation.

[Grunts softly] With her two young cubs, she's amongst 5,000 bears left in Scandinavia.

[Grunting softly] Their broad diet gives them an important role as forest gardeners spreading seeds.

And this mom will teach her cubs over 70 different edible plants.

But they're easily distracted... and always keen to play.

[Growling softly] Mom knows there's one lesson that can't wait.

These towering pine trees could save their lives, but only if they can climb.

They will be their escape route out of danger.

[Growling softly] Going up looks easy... [Growling] [Grunting] but it's harder coming down.

Mom encourages them from below.

[Grunting] ♪ ♪ Training over, the cubs snuggle in for a nourishing feed.

She has a couple more years to pass on her specialist knowledge of the forest before they become independent.

The summer months bring longer days... a brief season of plenty... [Birds chirping] and relaxation.

But some creatures never rest.

On the forest floor, one of the heartland's most productive inhabitants is busy at work... the wood ant.

They scour the forest floor in long processions, collecting pine needles, twigs, moss, and lichen... building materials to construct their giant mounds, some over 6 feet tall.

Each mound is like a city, home to half a million ants.

Just one ant colony can kill 20,000 insects a year, including many which would attack the trees.

This healthy forest is kept in balance by one of its smallest, most underrated residents.

But there are other creatures who have a more noticeable impact.

[Distant hooting] This woodland looks like a scene of destruction... but it's only during twilight hours that the perpetrator emerges... a Eurasian beaver... Scandinavia's largest rodent... [Splashing] over 3 feet long.

The beaver is an industrious engineer... building dams which flood the forest.

He dramatically transforms the landscape, creating a water world so he can access his food in safety.

[Water flowing] He dines on the vegetarian smorgasbord of bark, branches, leaves, and shoots.

His tools of the trade are his almost inch-long incisors that grow continuously.

He ferries some of this food to his lodge... that's only accessible by a secret underwater entrance.

It has a larder and a dry living space that keeps him safe from predators like lynx and wolves.

In serving his own needs, he is the architect of this maze of secluded rivers and lakes... helping to clean and restore waterways and creating habitats that support a rich diversity of life... [Splash] including the osprey.

[Splash] ♪ This male has flown over 4,000 miles from Africa... returning to this lake in southern Scandinavia.

[Chirping] He's now raising his two chicks solo as osprey moms leave for Africa as soon as their chicks can fly.

[Splash] [Chirping] He's a devoted parent.

Every extra day he stays and provides, his fledglings will get stronger.

But he must also keep the reserves to make his own marathon migration south.

[Chirping] For now, his chicks still use the family nest as their base and are completely reliant on him for meals.

With many years of experience, this dad's a pro at fishing... and the fledglings need to learn from him fast.

With exceptional eyesight, he pinpoints a fish, then dives at speeds over 75 miles an hour.

[Splash] He works relentlessly... [Splash] catching as many as 10 fish a day... for his gluttonous chicks.

♪ By early September... it's time for Dad to leave for Africa.

[Cheeping] One last feed, and his job is done.

♪ His chicks will now have to manage by themselves.

In just a few days, they'll begin their own epic migration to Africa... ♪ leaving these rich lakes quiet until ospreys return again next year.

At the end of summer, temperatures begin to fall and days get shorter, triggering an explosion of brilliant Autumn colors known as the Ruska in Finland.

Deciduous trees like birch, aspen, and rowan show off their magnificent shades of yellow and orange.

While on the damp ground, the forest's most fundamental relationship is revealed.

[Crunching] Fungi.

♪ They erupt from the forest floor as mushrooms to spread their spores before winter returns.

[Speaking Norwegian language] [Dog panting] With almost 10,000 varieties across Scandinavia, many families have secret spots where they collect edible mushrooms every year... [Man speaking Norwegian language] expressing their allemannsretten, or every man's right to roam and forage in nature.

Man: Perfect.

Boy: Yeah.

[Woman speaking Norwegian language] [Insects buzzing] Narrator: Mushrooms are all we can see at the surface of a massive underground fungal network that links into the roots of almost every tree and is vital for keeping the forest alive.

In this shallow, acidic soil, fungi have the key enzymes to provide essential nitrogen to the trees.

But to do this, the fungi need fuel, which they get from the trees as sugars in this age-old association.

Without this foundation of fungi, the landscape could turn to treeless tundra.

But in partnership, the boreal forests have been able to survive in the north.

[Animal howling] Autumn is an important season for the heartland's residents... a short window of opportunity to stock up before the cold arrives once again.

♪ This male brown bear must pack on the pounds before he goes into hibernation.

Over the next few weeks, he must eat 20,000 calories a day... which he can mostly get from nutrient-dense berries.

But he also needs protein.

With a remarkable sense of smell, he can sniff out food from several miles away.

♪ A wolverine is first to the feast.

This opportunist has no problem breaking into a carcass with his powerful bone-crunching jaws... [Ravens squawking] but he's not the only diner.

[Squawking continues] The ravens' noisy calls draw the bear closer.

[Squawking continues] [Splashing] [Squawking loudly] [Grunting] He can eat as much as 80 pounds in one sitting... but he needs to watch his back.

♪ [Squawking] ♪ Wolves were Odin's mythical warriors, and this hungry pack are on the offensive.

The bear is bigger and stronger than any wolf, but he's alone.

The 10-strong pack press closer.

Led by the alpha pair, they work as a team to intimidate the bear.

[Growling] He can't afford to abandon his meal.

[Grunting] One wolf tries to distract him away from the carcass... [Bear grunting; wolf growling] but the bear's determined.

He grabs whatever he can.

♪ ♪ [Growling] The wolf pack have the remains.

[Growling] The alpha pair eat first... but there's enough to feed the entire family... [Growling] [Growling loudly] though some are less keen on sharing.

[Growling] While this family is doing well, wolves are Scandinavia's rarest carnivore.

Hunted under a strict quota, there are fewer than 700 left.

These stealthy predators soon melt back into the shadows and safety of the forest.

[Wolves howling] [Ice cracking] The formation of ice and first dusting of snow heralds the return of winter... completing the seasonal cycle for life in the heartlands.

But there are some who have been eagerly awaiting the return of the ice.

Oskar Karlin is one of thousands of Scandinavians for whom wild or Nordic ice skating is a consuming passion.

Karlin: Winter is something I really look forward to.

You want to be on the ice as soon as possible, because the first ice is the best ice.

Narrator: Oskar's a cartographer making maps for a living... [Speaking native language] but to find the best ice takes detailed planning.

♪ As ice skating can be dangerous, he needs to be absolutely sure the ice is thick enough.

[Ice clinking] [Water bubbling] [Cracking] ♪ [Speaking native language] Karlin: You say 3.2 centimeters is the thinnest you can skate on.

[Tapping] and when it's almost 10 centimeters, you can almost drive a small car on it.

[Blades scrape on ice] ♪ Narrator: Oskar takes the lead, navigating a safe route across the lake.

[Blades scraping ice] Karlin: I would never ever skate alone.

That's so dangerous.

It's important to be quite focused, 'cause you never know if the ice is getting thinner or what's gonna happen.

Parts of your brain has to be scanning the ice and looking for dangers.

Narrator: There are lots of different kinds of ice, but the holy grail is newly formed black ice.

it's smooth, clear, and precariously thin.

Karlin: If the conditions are perfect when it freezes, it comes like purely black.

And that's the most magical ice to skate on.

[Splashing] [High-pitched tones pulsating] The sounds from the ice when it's quite thin sounds very strange, almost like laser beams.

Ptschew!

Ptschew!

It's a sound from another world.

It's almost like watching the northern lights, but with your ears.

[High-pitched tones continue] Sometimes when there's a little bit of water on the ice, it feels like you're skating in the sky or something because the reflections are incredible.

Living in the city, I love it, but it's quite hectic.

So, when I come out, I'm not so stressed.

Just constantly see this beautiful nature, and when you skate you-- you get happy from it.

[Blades scraping ice] So, the more you move, the--the happier you get.

Narrator: Scandinavia's raw wilderness is exhilarating for those who immerse themselves in it... but this perfect balance in nature is a fleeting and fragile one.

Karlin: The seasons every year is different.

If the temperature just changes a few degrees, then we will have almost no ice.

So, it's such a small variation in temperature that changes the whole thing.

The more time I spend in nature, I realize how fragile everything is.

♪ Narrator: The draw to be immersed in nature is so strong, Oskar and his friends will always seek out places where they can skate from dawn till dusk.

[Flames crackling] Karlin: Every time I'm--I'm out, I want to be out with my friends, uh, because then, we have a shared experience.

[Talking and laughing] If I've been out skating all day and I'm very tired, but I'm still so happy afterwards.

Narrator: For many Nordics, this close connection with the environment is the secret to a happy and fulfilled life.

♪ Throughout the seasons, the natural balance here is created from countless intricate relationships.

[Crunching] [Birds chirping] Today, it's becoming more fragile, impacted by human pressures and climate change.

Yet, just as the legendary tree Yggdrasil was the center of the Norse universe... [Grunting softly] forests still play a vital role interconnecting life.

They are the living, beating heart of Scandinavia.

♪ To order Wild Scandinavia on DVD, Visit ShopPBS, or call 1-800-PLAY-PBS This program is also available on Amazon Prime Video ♪