Narrator: It is the most storied place in America-- California.

♪ Still, its most amazing story has yet to be told-- a wealth of wildlife that has adapted to every possible habitat.

[Bird chirps] Narrator: Human ingenuity made a Golden Gate.

[Thunder] Human need transformed wild spaces.

But Nature granted Planet California its true gold... [Seagulls squawking] the most biodiversity in all the Americas... all bound together by vast rivers on land and sea and sky.

[Geese squawking] ♪ Narrator: Rivers do not just run through California.

They are its very lifeblood, and not just the ones you know about.

Other rivers--seldom seen-- also shape the Golden State.

There's the saltwater river in the sea, the California Current... ♪ traveled by wondrous creatures and generating a climate that is the envy of the world.

♪ And most surprising of all, the river in the sky... a flow of water vapor moving in from the coast, carrying more water than the Amazon River.

It is the hidden juggernaut of California's entire system.

♪ Together, these waterways have nurtured a land of abundance, for eons known only to the Native peoples of the continent.

That began to change less than a hundred years ago.

Many rivers on land no longer follow their ancient paths, their water diverted to agriculture and ever-growing cities, as California's population ballooned to 40 million people.

[Indistinct, overlapping chatter] Narrator: Fortunately, one river continued untamed-- the California Current-- a saltwater river in the sea.

It cools the coast and generates vitality where there would be a desert.

In the midst of the Pacific Ocean, it runs the entire length of the 1,800 miles of coastline from Northern California to the tip of Baja California.

♪ We can't see it, but animals can.

They sense it, taste it, sniff it out, and when they find it, they catch it like a train.

♪ It is a river of nutrient-rich, cold water that combines with upwellings from the ocean floor.

The resulting plankton blooms create a smorgasbord on the move.

Following the food, gray whales, hunted to near extinction till just sixty years ago.

♪ From their subarctic summer feeding grounds to their mating grounds in Baja, they cruise the California Current, five thousand miles in all.

♪ The California sea lion also catches the current down from the north, pursuing fellow travelers... salmon.

Some exit the current to chase the fish into the mouth of a freshwater river, the Klamath, a major salmon spawning ground.

[Gulls squawking] ♪ [Sea lions barking] In earlier times, millions of fish made the run.

Now, their dwindling numbers spark confrontation.

These resident sea lions guard their turf.

♪ But as the concentration of predators grows and the salmon decline, the situation grows desperate for both.

To complicate matters more, there's a new band of marauders in town... Steller sea lions, coming from the far north.

Bigger and faster than the natives, they dominate the beach.

♪ ♪ The heavyweight champ, the Steller sea lion, takes the meal.

A little harbor seal can't compete.

♪ With competition so fierce, it's a wonder any fish get through at all... ♪ yet instinct drives the salmon to keep trying.

♪ ♪ The harbor seal can hardly believe his good fortune-- all alone, with a trophy salmon.

It seems too good to be true... 'cause it is.

♪ ♪ ♪ ♪ [Sea birds squawking] Gone are the days when this beach provided fish for all.

When the pickings get too slim, the sea lions head back out to the California Current.

Some lucky salmon slip through.

♪ The legendary Klamath River stretches more than 250 miles from its headwaters in Oregon through the northern part of California.

♪ Traveling upstream, we follow the arduous journey of the salmon.

♪ For thousands of years, they returned to spawn and die, seeking out protected streams and fast-flowing water.

♪ All of the river's creatures are tied to the fate of the salmon.

♪ The Yurok people have always known this.

Amy Cordalis has helped her people regain thousands of acres of tribal lands.

For generations, they've fished the Klamath tributary known as Blue Creek.

Cordalis: When the salmon are coming home and headed up the river to their spawning grounds, Blue Creek is one of the first places that they rest, and they rebuild their strength in order to head up the river to their spawning grounds.

One of my favorite memories is catching one of my first fairly big fish.

Narrator: Without fish, the Yurok nets and traditions are empty.

Cordalis: Salmon are at the heart of Yurok culture.

The salmon have supported the Yurok people since the beginning of time, and because of that, we have this deep, deep connection to those fish.

So one of the things we're working on is bringing back those salmon in ways that can continue to support our fishing way of life.

Narrator: The next hurdle for the Yurok and the salmon-- four hydroelectric dams barring the way to the spawning grounds.

Cordalis: We fight hard for river restoration.

We fight hard for salmon restoration.

Everything we do in some ways revolves around the river.

Narrator: The decrease in flow makes the water too shallow and warm.

What was once an epic journey is now limited to just a few isolated sites downstream of the dams.

Cordalis: When the dams are removed, we will restore salmon access to over 350 miles of spawning habitat in northern California and southern Oregon.

The salmon will finally go home again after almost a hundred years.

Narrator: The salmon's long swim-- sometimes thousands of miles through the ocean and then upstream against the river's current-- uses up every last ounce of energy, draining even the fish's colors away.

Just south of Blue Creek, in the cool shade of old-growth California Redwoods, a few more small streams shelter little fish from heat and predators.

Salmon parr imprint to their home stream through its unique scent.

They will return here only once, to die.

But out of the salmon's death comes life, for it fertilizes the trees that protected its infancy.

[Birds chirping] ♪ Here be giants-- the redwoods, the tallest trees on Earth.

♪ Every year, more than 30 million tourists visit California's redwood forests.

♪ Because of their size, much of the life story of the redwood remains a mystery.

♪ It takes courage as well as curiosity to unlock their secrets.

Only recently did scientists solve a piece of the puzzle of their phenomenal height.

♪ How do they manage to draw water up 38 stories?

Turns out...they don't.

Instead, redwoods harvest moisture from a flow of water vapor, a river in the sky.

Throughout the year, a cold fog blowing east from the California Current is pulled inland by the hot interior, covering the forest in a blanket of moisture.

The trees take as much as 40% of their liquids directly out of the air.

♪ The moist conditions foster yet another ecosystem in the understory.

[Bird squawking] The fruiting body of a mycorrhizae fungus is just the tip of the iceberg.

The little mushroom and gigantic redwood are allies.

To find out about their extraordinary relationship, we must go deeper.

[Bird squawking] ♪ Redwood roots can extend more than fifty feet in any direction.

♪ Locking roots with their neighbors, they help hold each other up.

♪ The fungus participates in this arrangement by forming tips around the tree roots.

♪ They pass along hard-to-reach soil nutrients, as well as shielding the trees from disease.

♪ In exchange, the tree supplies sugars to the fungus.

This cooperative system also acts as a communications network, through which trees send alerts to their neighbors about predators and other dangers.

♪ Less than 5% of the Redwood Forest remains today.

Forests are critical to the existence of another singular creature.

The California newt lives on land much of the year, but she was born in water, and to water she returns to breed.

♪ Early summer brings her back to her natal stream, where others have already left their eggs hidden among the rocks.

Her extended belly shows she's bred and will deposit her own eggs soon.

♪ Three males hold an unmated female in the center of their mating dance.

♪ She passes by a ball of larvae that will soon hatch.

♪ ♪ She needs to place her eggs somewhere safe from predators and rushing water.

♪ The egg masses range from just a few to nearly 50, and she lays up to six masses in a single day.

♪ Survival is a numbers game.

Without a shell, little separates the developing larvae from a hungry world.

♪ [Female background singers vocalizing] ♪ Narrator: If conditions are right, the larvae will hatch in as little as two weeks.

♪ The eye of newt, a notorious ingredient... but it's her skin that belongs in Shakespeare's witch's brew.

It contains a powerful neurotoxin, hundreds of times more dangerous than cyanide.

♪ The giant water bug doesn't abandon his brood.

He wears his eggs on his back and tends them until they hatch.

♪ The predatory water bug keeps an eye on the developing juvenile newts.

♪ His painful poison liquifies the innards of his victim, which he then sucks out, avoiding its poisonous skin.

♪ He poses no problem for the grown newt... ♪ and the garter snake also knows better than to tangle with this femme fatale.

♪ ♪ As summer intensifies and ephemeral streams disappear, back into the old-growth forest she goes.

♪ The California newt thrives in two elements, but there's one that all forest creatures, and increasingly, all Californians, fear-- fire.

[Thunder] Triggered by lightning, it has always been a part of the natural cycle.

♪ But today, fire season lasts longer and burns bigger, with the vast majority of blazes started by human folly or neglect.

♪ In the last two years, the six largest wildfires in California history consumed over three million acres, 7,000 buildings, 24 human lives.

♪ The prime suspect-- climate change, with its intensified storms and prolonged droughts.

♪ ♪ The Santa Ana winds, blowing from the interior, also fan the flames, drying out an already parched landscape.

♪ As urbanites intrude on forests, they move into danger's path.

♪ Another devastating casualty... the sequoia forest, mountain conifers that are cousins to the redwood and even larger in girth.

Ten percent of the mature giants-- many more than 2,000 years old-- perished in a single fire.

♪ Nature's antidote has always been annual winter rains, borne on California's most powerful river in the sky... the Atmospheric River.

♪ With land-based water sources drying up, California increasingly relies on it to put the fire out.

♪ But shifting weather patterns have delayed the rains, amplifying the danger.

♪ 500 miles south of the Redwoods, the river in the sea-- the California Current-- continues to nurture a different sort of forest.

♪ Stands of giant kelp mark the halfway point for one of Earth's longest migrations.

♪ A gray whale making her annual journey has a calf in tow.

Whales sometimes use the kelp to hide their babies from predators.

♪ Sea otters make the forest their home year-round.

Resting on top of the floating canopy, they forage shellfish and sea urchins from the ocean floor.

♪ The kelp is truly a lifeline for otters.

When sleeping, they even wrap themselves in it so they won't float away.

♪ On their strenuous journey to Baja, the whales depend almost entirely on the fat built up during the summer in their Arctic feeding grounds.

♪ These are lean times, contrasting sharply with the land of plenty they now swim by-- Malibu.

How many casual beachgoers even notice the 20,000 whales swimming just offshore?

Sometimes, they're hard to ignore.

Since 2019, a sudden die-off of gray whales has mystified scientists.

♪ Mother and calf push on through all hazards.

They still have another month till they reach their destination.

♪ The whales' passage heralds the arrival of early winter and another long-awaited visitor... the Atmospheric River... the airborne current traveling from across the Pacific, packed with warm, moist air.

Like jet fuel, it injects the fog of the California Current with force and energy.

♪ It pushes past the coastal areas and ever eastward, flowing over the dry interior until it meets the mountains.

There, it is corralled by jagged peaks that reach 14,000 feet into the air.

♪ As the warm, wet air mass meets the frigid mountain air, the moisture is wrung out, like a sponge being squeezed.

♪ It falls as snow, hundreds of centimeters annually in some places.

That snowpack stores the wealth of California, upon which all the other riches depend.

♪ In the heart of the Sierra Nevada Mountains lies a region so breathtaking, it inspired America's National Park system... [Birds chirping] Yosemite.

♪ Four million tourists make a pilgrimage annually to see its wonders... ♪ the granite faces that challenge the world's greatest rock climbers and dozens of waterfalls, the gift of the Atmospheric River.

♪ They feed California's priceless supply of surface water.

Much of this water will eventually end up 300 miles away, in Los Angeles, with its eight million thirsty people.

Yosemite is encompassed by a wilderness so vast and rugged, most of it has been left to the wild things.

♪ This is the kingdom of the tenacious Sierra Nevada bighorn sheep.

♪ Over hundreds of thousands of years, it has adapted to the harshest of conditions, allowing it to go where few animals can follow.

♪ That includes scientists, who must be just as tough.

♪ The sheep can range up to 60 miles, much of it in craggy, inhospitable peaks.

They're a moving target that's hard to find.

To track them, Tom Stephenson and his team use satellite and radio telemetry.

Stephenson: Sierra bighorn live in this steep environment because that's their primary defense against predators.

They have hooves that are unique relative to the other hooved animals in that their hooves are much softer.

They're able to maintain their grip in steep terrain, and so they live up in this rugged environment largely to avoid predators so that if they feel threatened, they can run and escape into that terrain.

Narrator: The snowpack is key to their survival, too, for it fosters the forage and vegetation that make this niche habitat possible.

♪ Once, their sheer numbers made them the symbol of the Sierras, but, devastated by market hunting and diseases from domestic sheep, there are just 600 left.

♪ Their unique adaptations may soon vanish from the world, especially if they fall prey to one other tough, sure-footed animal.

♪ ♪ Mountain lions are relentless in their pursuit.

Surprising their prey from behind, they often take down animals larger than themselves and can decimate a herd of bighorn in a single season.

♪ This lioness goes to great lengths to protect her hard-won prey, dragging it hundreds of yards to hide it from scavengers.

♪ To safeguard the few remaining bighorns, sheep-killing lions have to be collared and monitored for their own good.

One of a handful of people who have the skill to follow lions in this vast terrain, Jeff Davis has been tracking the big cats for decades.

[Distant animal screeches] Davis: Yeah, this is Blondie.

She, uh, she's got a really good mind.

She's good in bad country.

We get along good with mules.

[Dog barks] We look for tracks and our dogs look for tracks, and when they find them, they follow them, and we follow them.

Narrator: It's an exacting and perilous job.

♪ But when he finds a track in soft soil, Davis doesn't shy away.

Davis: I've never had an instance with a mountain lion that I've ever felt threatened.

Normally, they're not as aggressive or bold as a person would think.

Narrator: While the threat to sheep may be real, lions themselves demand our sympathy.

♪ Davis: Anybody that likes wildlife, how can they not love lions?

Good gosh.

They're so tough, they travel so far, and if there's something to eat, they will find it.

As long as we have sufficient habitat and prey, there'll always be mountain lions in California.

Narrator: A mountain lion on the hunt may cover hundreds of miles.

Its most common quarry is the endemic California mule deer.

♪ [Coyotes howling and yapping] Tens of thousands roam the highlands and river valleys of the central and southern part of the state.

♪ [Howling and yapping continue] When a predator is spotted, a mule deer springs into the air to warn the herd.

♪ Not all get the message.

♪ She's brought down a huge buck that could last a solo lion a week... but she is not alone.

With a family to provide for, she hunts every few days.

[Kittens screech, lioness purrs] Just a couple months old, this little one seems eager to help, but it is, in fact, quite helpless.

♪ The kittens take up to a year learning the skills they'll need to make it on their own.

♪ Sibling spats hone fighting chops that will come in handy when they finally separate from Mom.

[Kittens growl] She spends nearly three-quarters of her life either pregnant or raising and protecting her young.

Davis: The threats to the kittens?

Obviously, the highway.

Everything will kill 'em: a coyote'll kill 'em, a bear'll kill 'em.

The closer she is to the kittens, the more secure and the higher the likelihood that they will survive.

Narrator: Hidden in their den by the river, they're safe for now.

The deer mice are safe, too.

The inexperienced kitten isn't quite sure what to do.

♪ Still, it's only a matter of time till they take their place as top predators.

♪ Across the river, in a quintessentially western landscape, love is in the air.

Female sage grouse visit a breeding ground-- known as a lek-- to shop for a mate.

[Grouse clucking] ♪ The girls are notoriously finicky.

[Clucking continues] ♪ At more than four pounds, the male is substantial, and his amorous display makes him even larger.

♪ Swelling the twin air sacs on his chest and swishing his feathers, he's dressed to impress.

♪ The males square off, defending their bit of turf.

♪ ♪ ♪ The flashier fellow runs off the less-experienced bird, hoping to catch the eye of the ladies.

♪ His threatened species depends on it.

♪ But populations can recover.

California's native Tule elk are proof.

[Elk calling] Back from the brink of extinction, today's elk are all descendants of a single breeding pair-- an Adam and Eve-- sheltered on one ranch.

♪ Tom Stephenson and his California Fish and Wildlife team would like to replicate that feat.

The urgency of the Sierra bighorn's decline moves them to act.

Air Bighorn is a heavy and precious load.

For the last several years, they've selected matrilineal family groups from herds large enough to spare a few members.

They're relocated to new areas as seed stock.

[Helicopter blades whirring] Each moment counts, and the crew works quickly to reduce the animals' stress.

The temporary discomfort is a small price for a chance to restore the bighorn to its former range.

Stephenson: If we have them widely distributed, then they're much more resilient to threats, whether it's disease or climate change or predation that can heavily impact one herd.

♪ Narrator: But first, the bighorn are thoroughly checked out.

All the measurements, data, and tracking devices will help the scientists determine the success of this ground-breaking experiment.

A sonogram reveals good news: this ewe is pregnant.

♪ Fifty years ago, bighorn sheep could only be found in two small regions of the Sierra Nevadas.

With the movement of this herd, the number of ranges could expand to thirteen.

♪ But only if the animals choose to adopt their new placement, an hour away by truck.

♪ The new location promises an ample snowpack, supporting the vegetation the herd will need.

♪ What will the sheep make of their brave new world?

♪ ♪ ♪ ♪ Three hundred miles to the north, another water story begins, ironically, with fire.

Mt.

Shasta is part of the Pacific Rim's Ring of Fire, last erupting in 1786.

♪ Its lava tubes filter and refine rainfall, snow, and glacier melt.

♪ It also produces some of the purest water on Earth.

♪ The ever-growing rivulets eventually fill pristine springs while, below the surface, lava tubes flow to distant aquifers.

Combined, they provide the drinking water for about 20% of California's 40 million residents.

[Geese squawking] It offers respite for some beautiful visitors, too.

♪ Every winter, more than a billion birds travel the corridor known as the Pacific Flyway.

♪ After a 3,000-mile journey, enormous flocks of snow geese from the Arctic come to rest in California's Central Valley, their winter home.

Their once-vast marshes have been reduced to small refuges, an attempt to divert the birds from farmers' fields.

Other migratory waterfowl arrive to share the diminishing resources... but the bulk of the water goes to one of the richest agricultural regions in the world.

Today, farming soaks up nearly 40% of California's fresh water.

♪ A conflict looms between competing human stakeholders, while wildlife has no voice.

♪ With climate change spiraling, the crisis deepens.

Since 2010 alone, there have been seven years of severe drought.

♪ Once-productive lowland lakes become saline wastelands.

♪ It's good for the brine flies, which gobble up algae in the shallows and shores.

[Brine flies buzz] [Birds chirping and squawking] ♪ Other California landscapes demonstrate what happens when the trend goes too far.

♪ The apogee of high salinity is Mono Lake.

♪ Long ago, trapped water dissolved the salt in the rocks, creating the magical tufa towers.

♪ They hold vigil over a deadly space.

♪ Little survives here but algae and arsenic-eating bacteria.

♪ Death Valley once held a gigantic inland lake as well.

Its ghost is still limned in rippling sands and vast salt fields.

♪ Hundreds of feet below sea level, the narrow valley circulates heat like a convection oven.

♪ The mercury can climb to 134 degrees Fahrenheit, making Death Valley the hottest place on Earth.

♪ A vision of a desiccated future?

♪ [Birds chirping] But even here, life stubbornly holds on.

The Joshua tree perseveres through decades of drought-like conditions, with adaptations that harvest and store meager rainfall.

Water-loving palm trees are a clue that this place holds a secret.

[Bird calling] Underground rivers convey water from distant mountains.

They feed an aquifer so large, it could fill two and a half million Olympic pools.

This is the miracle that created Palm Springs-- an oasis in the desert.

Each of its famous golf courses soaks up as much water in a day as a family of four uses in a year-- an unsustainable luxury.

[Bird of prey screeches] The arid lands extend hundreds of miles to the south, all the way down the Baja peninsula.

Off its southern tip, the cold California Current slows and dissipates as it mixes with warm currents flowing from the south.

The dynamic combination spawns stunning bays and lagoons, radiating with life on sand, sea, and in the air.

[Sea birds squawking] Vast colonies of brown pelicans come here for the bounty of the California Current.

A breeding pair builds a nest of grass and sticks right on the rocky cliffs.

Unlike most birds that use their breasts to warm their clutches, a pelican uses its ample feet to make them cool.

[Squawking continues] Pelicans dive-bomb their prey, stunning them with their bills.

Air sacs in their breasts cushion their fall as they hit the water.

The pelican's famous pouch acts as a scoop.

Like a fishing net, it draws up water, which drains out when they surface, leaving only fish, to be swallowed whole.

Between the sand and waves, a glorious patch of green-- mangroves.

And where there are mangroves, the frigatebird is sure to follow.

[Frigatebirds screeching] Master fliers, they can soar up to two and a half miles above the earth.

The male displays his red throat to attract a mate.

They hatch but one chick, and it is never left alone, lest the neighbors decide to have it for a snack.

♪ Soaring on wings that stretch seven feet tip to tip, frigatebirds scour the river in the sea for their youngsters' next meal.

♪ Their sharp eyes spot prey from hundreds of feet below them.

[Sea lions barking] They in turn are watched by sunbathing sea lions, who know the birds will cue them when the game is afoot.

♪ [Frigatebirds screeching] ♪ Things heat up with the arrival of the Ferrari of fishes-- the striped marlin.

♪ Lightning-quick, these lovers of the bright blue water range throughout the southern reaches of the California Current.

♪ Together, they herd small schools into an ever-growing, panicked mass.

♪ ♪ When it gets excited, the marlin "lights up" and changes color from silver to electric blue.

Marlin turn black just before they eat.

♪ When it is attacked by sharks, it wields its bill like a spear and attacks the onrushing threat.

♪ ♪ ♪ At last, the great sojourner arrives after a 5,000-mile trip.

♪ The change of scene is radical.

♪ Many gray whales have already given birth in these warm waters.

♪ Now, some begin their courtship.

♪ For one of the very first times, we witness two males engaging a female.

Using their pectoral fins and massive heads, they encourage her to roll over.

Only if she is receptive to their advances will they manage to mate, for the whales' embrace is belly to belly.

♪ These rare images capture a moment of hope.

♪ This magnificent species has beaten the odds, coming back from oblivion's edge.

♪ Even though we caused that disaster, they seem pleased to make our acquaintance.

♪ A gray whale urges her calf forward, as if eager to bridge the gulf between species.

Woman: Oh, that is so beautiful.

Narrator: Wild places and human spaces are bound together, for water knows no boundaries.

♪ Instead, it connects us all... ♪ and connection is the key to coexistence.

♪ ♪ ♪ ♪ ♪ Announcer: To order "Planet California" on DVD, visit ShopPBS or call 1-800-PLAY-PBS.

This program is also available on Amazon Prime Video.

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