Narrator: Stradling two countries is the most famous waterfall in the world, where every second, over 3,000 tons of water flow over the edge.

It's an epic sight that keeps tourists coming to experience Niagara Falls.

Man: You feel like a tiny little speck in the water that surrounds you.

Narrator: These falls are central to what is the largest freshwater system on Earth.

Here you'll find tiny water hunters the size of your thumb and ancient trees that grow from bare rock.

Man 2: The habitat that many of the trees call home is just such a magical area of scenery.

Narrator: Meet the guardians of these places... Man 3: As you dive, it feels at times like you're flying.

Narrator: And discover the geological wonder of Niagara Falls.

♪ ♪ [Birds cawing] Narrator: Spring is the beginning of many new tales.

And here, along the jagged shoreline, new stories are being written.

Thousands of ring-billed gulls are packed tightly together at the edge of the river.

And they're here for a single reason.

♪ Families of all ages are just beginning their season.

Some are days old... while others are just minutes old.

These chicks are born into a world of perpetual mist and wind.

[Birds cawing] It's a tough beginning.

And this first-time mom isn't making things any easier.

But feeling safe and secure is the most important thing.

Crucial when your home lies in the shadow of the world's most iconic waterfall.

[Birds cawing] ♪ Niagara Falls is one of nature's greatest displays of might.

♪ A towering wall of water plunging over 180 feet... enough to fill an Olympic-size swimming pool every second.

Niagara isn't one waterfall, but 3, spanning the border between Canada and the United States.

The Niagara River is powered by 4 of the 5 Great Lakes, a vital artery connecting Lake Erie to Lake Ontario.

It is the heartbeat of the largest freshwater ecosystem on Earth... bigger than the state of Texas and more precious than oil.

[Chirping] It is home to ancient forests that grow from stone... tiny hunters no bigger than your thumb... and millions of migratory birds that depend on this wealth of water for their survival.

[Birds cawing] ♪ For these gulls, Niagara Falls is not only their home, but their hunting grounds.

Along the edge of the falls, they levy an aerial assault on small fish.

♪ Making a living here means making bold choices.

♪ The violent power of the current can quickly overwhelm even the most seasoned hunter.

To survive, these young chicks must become masters of the skies.

Or, at the very least, keep their balance.

These awkward steps are their first on the road to independence.

In just a month or so, they'll be on their own.

♪ The cliffs that these gulls call home are part of a much larger geographical feature.

♪ The Niagara Escarpment is a massive cliff face nearly a thousand miles long.

It stretches from Niagara Falls, across into Canada... and down the eastern edge of Wisconsin, encompassing Lake Erie, Lake Huron, and Lake Michigan.

♪ The story of its origins began long ago when the world was mostly water.

Woman: I have a special family and cultural connection to the Great Lakes and the Niagara Escarpment, which is really the backbone of our whole region.

It defines everything from how everything looks to the ecology to how you move on the landscape to how you cross places.

Narrator: Jenna McGuire is a scientific illustrator and explorer of deep time.

Jenna: This is an ecosystem preserved in stone, that mudflat area.

This looks a little bit more like a reef structure.

Jenna, voice-over: It's not just the odd bit of animal or the odd thing that's fallen in the mud somewhere.

Here is a coral and a little brachiopod.

An entire ecosystem is represented in this rock.

Narrator: Carved away by glacial meltwater, the Niagara Escarpment is the exposed edge of a fossilized sea that existed some 430 million years ago.

The very dolostone that forms this massive cliff is made from thousands of living organisms turned into stone.

Here's a great example of a bed of brachiopods built right into the escarpment.

So, all of the organisms that make up the Niagara Escarpment can often be found as fossils.

And here's a good example of what brachiopods look like.

They look like seashells, like a clam or mussel, but they're a different animal altogether.

And then here's a cast of the outside of a squid shell.

Narrator: 430 million years ago, this region was just a few degrees south of the equator.

The clear, warm water would have been ideal for coral reefs and the diversity of life they supported.

Jenna: Where we're sitting today, if we had our snorkel and our swimming gear, we would be on a beautiful tropical reef.

Very, very hot.

The reef that built the Niagara Escarpment is very similar to the Great Barrier Reef in Australia today.

And there would be all kinds of colorful corals... squid squirting through the water... sponges... just like we see today on a coral reef, only a few creatures are missing because they hadn't evolved yet.

♪ Narrator: Jenna has re-created a portion of this ancient reef to help her more accurately render the organisms that inhabited this world.

Jenna: In these ancient Silurian oceans, the top predator wasn't sharks.

They hadn't evolved yet.

It would have been things like large, shelled squid.

Narrator: Giant shelled cephalopods patrolled the shallow seas hunting trilobites and prying brachiopods from their shells.

Over time, these cephalopods would lose their shells and become the squids and octopuses we know today.

But perhaps the greatest predators of the Silurian Sea were the giant sea scorpions.

Jenna: Some grew to be longer than a human is tall, so they were actually some of the biggest arthropods that ever lived.

Narrator: Sea scorpions stalked the very coral reefs that formed the Niagara Escarpment.

With every brushstroke, Jenna brings to life a world that once was.

A thriving community of animals turned into stone.

Only a portion of the Niagara Escarpment can be seen from above, the rest lies far below.

Sam Skelton has grown up on the shores of Lake Erie and has spent most of his life probing the depths of the Great Lakes.

Sam: Over time, being around these bodies of water so much, you start to wonder what it's like underneath the water.

Narrator: This is Sam's first dive along the edge of the Niagara Escarpment at the tip of the Bruce Peninsula.

Sam: As you dive the escarpment, you can imagine what it looks like underneath Niagara Falls.

Between the clarity and the magnitude of these rocks, it feels at times like you're flying.

Narrator: The visible portion of the escarpment above ground is only a fraction of the whole.

In places, the escarpment reaches a depth of over 600 feet, 4 times the size of Niagara Falls.

Sam: You come up to this massive, striking cliff, and then there's just a hole in the wall, and you swim up to it, and you see that there's these tunnels.

Narrator: The escarpment is a labyrinth of caves and narrow passageways carved away by the relentless force of water.

Sam: You go through this tight tunnel, and it gets claustrophobic.

Your tank scraping up on the top.

Your belly is going against the bottom.

And then it opens up into this massive room, half under water, half above water, like you're between two giant buildings.

The scale is really striking.

Narrator: The very same water that erodes away the escarpment here powers the mighty Niagara Falls some 200 miles away.

The Niagara River is not only the engine that drives the falls, but the power behind a vast wetland ecosystem.

Man: The Niagara River corridor is full of places that allow for the transition zone from water onto land where plants and wildlife thrive.

Narrator: For aquatic ecologist Marcus Rosten, these wetlands hold secrets both large and small.

Marcus: The entire eastern end of Lake Erie, going into the Niagara River corridor, was historically a shallow water marsh that was an aquatic heaven for wildlife that lives here.

So, this is an American bullfrog, the largest frog species in New York state, the largest frog species in the Niagara River corridor.

Narrator: Wetlands are among the most productive and diverse ecosystems on Earth.

Every animal plays a role in maintaining the balance of this delicate system.

Marcus: What you see when you really dive into a wetland is that there is a rainforest-like breath of life beneath that surface.

♪ ♪ Narrator: These thriving wetlands attract some unusual predators.

It's a water shrew, a tiny insectivore no bigger than your thumb.

But don't be fooled by its size.

Water shrews are the cheetahs of the wetlands.

Water shrews have the highest metabolism of any diving mammal.

They seldom go more than a few hours without a meal.

And this shrew hasn't eaten all morning.

The edge of the stream provides some rewards, but he'll need more than an insect carcass to satisfy his appetite.

His favorite meals are found just below the water's surface.

As the smallest diving mammal on Earth, hunting for this shrew lasts just a few seconds.

But what happens underwater is remarkable.

Because of his poor eyesight, he must rely on a complex hunting strategy.

He scans the surface to detect the slightest break in the water.

Then he forages along the bottom, trying to shake loose his prey.

♪ When his long whiskers detect movement, he gives chase.

Crayfish can be elusive.

And they're also half his size.

But with reflexes 10 times faster than our own... he eventually outpaces them.

Slower prey, like these dragonfly nymphs waiting in ambush for their own meal, rely on stealth to remain undetected.

To find the camouflaged nymphs, he uses a rare superpower-- the ability to sniff out prey underwater.

By blowing tiny bubbles of air, he can detect scent particles in the water.

But even with his advanced arsenal, hunting often turns into an elaborate game of hide and seek.

♪ But once a shrew locks onto its prey, it rarely escapes.

♪ This elite predator often takes down prey twice his size.

♪ But for now, he will settle for a nymph, at least for the next few minutes.

The water shrew's predatory skills keep many invertebrates in check.

Yet the shrew's world is rapidly shrinking.

[Birds cawing] The Niagara region has lost nearly 90% of its original wetlands to human development.

♪ And this fragmentation threatens all who call these marshlands home... including one of the most ancient.

Snapping turtles have haunted our wetlands virtually unchanged for 90 million years.

They witnessed the extinction of the dinosaurs, the rise of mammals, and the recessions of the massive glaciers that created the Great Lakes.

But today, they are facing the greatest challenge in their long history.

In spring, mature females leave the comfort of their pond in search of a suitable place to lay their eggs.

When this turtle was just a hatchling, this entire area was wetlands.

But today, roads transect her shrinking home.

What should be a routine journey has become a perilous one.

[Horn honking] Females searching for a nest site are drawn to roads.

The mixture of sand and gravel along the embankment makes the perfect nesting material.

It's a dangerous combination.

Tonight, she will lay between 20 and 50 eggs.

♪ A turtle hatchling's fate depends upon its mother's choice of nest sites... and this mother has chosen a precarious location.

For every 1,400 eggs she lays, only about one will survive to adulthood.

It's no small miracle that she has survived this long.

But the road ahead is an uncertain one.

Man: The Niagara Escarpment has always represented a special place to me.

Because of the widespread development across most of southern Ontario, the escarpment has protected a ribbon of wilderness habitat that is just a stone's throw away from where millions of people reside.

Narrator: Ron Gould is a biologist with Ontario Parks and the guardian of a very special place.

This is the Three Kings location, Jenny, between these 3 big bowls here.

Narrator: The oldest living trees in Ontario reside here, along the jagged cliffs of the Niagara Escarpment.

Ron, voice-over: The habitat that many of the trees call home is just such a magical area of scenery.

A big part of the fun with my job in monitoring the ancient Cedar Forest is the journey and the challenges of getting to the trees.

Ron: So, we are back at tree 811, germination date of 701 AD.

So this year it puts it at 1,322 years of age.

Narrator: Life is precarious for these cliff-dwelling elders.

The slightest shift in their foundation or a falling rock from above could mean the end for an ancient cedar.

Most of the living circumference of the tree has already perished long ago, but some of these living sections are now being impacted by the sharp falling rocks.

Narrator: But their greatest challenge is beginning life itself.

♪ Ron, voice-over: The mathematical improbability of having a successfully germinating little seedling land in the right crack or fissure or a little ledge along the cliff face... is pretty mind-boggling, to be honest.

Narrator: Eastern white cedars can generate up to 260,000 seeds.

Scattered by wind, many fall into the lake below.

A rare seed will find a crack or crevice to germinate in.

Ron, voice-over: With the harsh growing conditions, general lack of moisture, precipitation, soil, nutrients, those little, tiny seedlings, if they are lucky enough to land in the right spot, really have an uphill slope to climb.

Narrator: The first few years of life are the most critical for their survival.

♪ Ron, voice-over: The ancient cedar story to me has always been about just ordinary species being able to do extraordinary things.

Narrator: From season to season, the young trees cling to the bare rock which is eroding with each passing year.

Those few cedars along the cliff that survive the harsh living conditions have become the ancient ones.

The very inaccessibility of their home has kept them alive.

As settlers marched across Ontario, logging and building their cities, the cedars remained untouched by human hands.

They survived the axes that felled their topside cousins, the storms that raged across this inland sea, and they have thrived, undisturbed for over a thousand years.

[Birds cawing] It's early August and our gull chicks have grown up fast.

Although mom and dad are still serving dinner, in a week or so that will all change.

Once these chicks fledge, they'll be off the couch and out of the house.

They're gonna need to find their own meal.

But until then, both gulls and people are taking advantage of these warm summer days.

♪ Marcus, voice-over: As you travel upriver, the modern world seems to fall away.

It feels like a trip back in time.

Narrator: And for Marcus, these summer days are an opportunity to experience the power and majesty of Niagara Falls.

You feel like a tiny little speck in the water that surrounds you.

Marcus, voice-over: Overwhelms pretty much all of your senses.

You can't do anything but feel like you're right there in the moment.

Narrator: And this is true of the millions of visitors that come here every year.

♪ ♪ For some, the end of summer marks the beginning of a whole new chapter.

One that begins with a tiny rumble just beneath the earth.

For the past two and a half months, these baby snapping turtles have been incubating underground.

[Birds chirping] It's their first day above ground, and they are vulnerable.

Their tiny shells are still soft, making them an easy meal.

Now, guided by instinct, just as their ancestors have done for millions of years, they will journey half a mile or more to reach a pond or lake.

The late summer sun bears down on the defenseless hatchling.

He must find refuge, and soon.

[Passing vehicles] But there's a problem.

♪ Instincts are powerful, and he presses forward.

♪ ♪ This hatchling has survived his first big test.

With the odds stacked against them, only a handful of hatchlings make it to water.

This small pond will become his new home.

But even ponds are a dangerous refuge.

Until the hatchling reaches adulthood, he's on everyone's menu.

With so many threats facing the species, the future of snapping turtles is a precarious one.

♪ Summer is coming to a close.

Plants are beginning to conserve their energy for the brutal winter ahead.

♪ Jenna: Autumn is a reminder of our place in this endless journey around the sun.

Narrator: For Jenna, autumn brings a new pallet of colors.

Jenna: The Niagara Escarpment is capped with this beautiful verdant green forest, but in autumn, that forest alights into yellows and oranges and reds.

Likewise, down on the forest floor, all kinds of mushrooms of every color erupt through those colored leaves.

♪ And it's just a complete wardrobe change.

♪ ♪ Narrator: Along with golden hues come autumn rains.

[Thunder] [Thunder] All along the escarpment, countless rivers and streams swell with rainwater.

Dormant waterfalls reawaken.

♪ Water is the force that defines the region.

It's this relentless flow of water that gave birth to Niagara Falls.

The river slowly eroded away the escarpment to form the great gorge.

And 4 miles downriver from the fall's current location is a swirling eddy known as the Niagara Whirlpool.

Less than 5,000 years ago, Niagara Falls stood here.

As water erodes away the escarpment, the falls continue to move, one foot per year.

By the time leaves start dropping from the trees... winter is already knocking at autumn's door.

♪ ♪ Rocks and trees around the falls are enveloped in frozen mist.

♪ Winter has arrived to Niagara.

♪ Across the Niagara region, snow and ice are beginning to take hold.

♪ ♪ With his home quickly freezing over, this beaver has little time to waste.

♪ His busy work has attracted the attention of some curious onlookers... a family of river otters.

And they are starved for entertainment.

But this beaver has no time for their childish games.

He's planning ahead for the worst of winter.

Beavers don't hibernate, so he must pack away enough food to last him through the bitter months ahead.

♪ The beaver's pantry is at the bottom of the pond.

Once the pond has frozen solid, he can slip down to the basement for a quick snack.

♪ Soon the beaver will be safely tucked away in his lodge.

But this rowdy bunch is just beginning their season.

Otters are at home in these frigid waters.

And ice fishing is in their blood.

This family alone will consume enough fish to clean out a small seafood market.

And that doesn't leave much for the neighbors.

♪ Man on radio: Cloudy skies with flurries today.

Total accumulations of 3 inches.

Tonight's low near 15.

It's currently 28 degrees.

Narrator: The sudden drop in temperature is exactly what Marcus has been waiting for... a signal that peak birding season has arrived.

Marcus: I'm lucky to live right near the Niagara River, so I am a stone's throw away from one of the best birding locations in North America.

A lot of birds take advantage of hanging out between these two islands, where you still have enough current the water is not usually going to ice over.

Narrator: Water birds that have spent their summers in the Arctic return to the banks of the Niagara River.

♪ [Trunk closes] In a landscape mostly covered in snow and ice, these open waters are a magnet.

Marcus: When you get closer to the falls around here, there's habitat for fish.

And when there's habitat for fish, there's habitat for birds that eat fish.

So, this turns into a great place to hang out.

Narrator: This time of year Niagara is famous for one of the largest and most diverse concentrations of gulls in the world.

♪ All along the Niagara River, gulls are beginning to gather in large numbers.

At least 18 different species of gulls can be found here.

For some, the river marks the end of a very long journey.

Bonaparte's gulls breed as far north as the Arctic National Wildlife Refuge and overwinter in the Niagara region.

Nearly 30% of the entire global population can be found along the Niagara River.

They are here for a feast.

Emerald shiners are a tiny fish that are abundant in the Niagara River, and they're the primary source of food for these gulls.

[Birds cawing] The slightest movement in the water spurs them into action.

♪ And while these gulls are fighting over a single fish, upriver, the story is different.

A large school of emerald shiners has drawn the attention of these common terns.

♪ And it doesn't take long for the Bonapartes to catch wind of the hunt.

♪ And a feeding frenzy has begun.

[Birds squawking] ♪ ♪ They must take advantage of these bountiful days while they last.

A powerful polar vortex has gripped the region... locking Lake Huron in ice.

♪ Bone-chilling, subzero temperatures transform Niagara Falls into a winter wonderland.

It looks as if Elsa has cast her icy spell.

♪ It is a breathtaking world of ice sculpted by water.

♪ ♪ [Wind howling] Ice pushes farther across the Niagara region, drawing one of winter's most masterful hunters.

[Screeching] Snowy owls spend most of the year in the Arctic, subsisting almost exclusively on lemmings.

But here on the ice floes of Lake Huron, there are new opportunities.

[Chirping] The broken ice along the lake makes for the perfect cover.

The snowy owl's survival strategy is revealed in her eyes.

The striking yellow color indicates a hunter by day.

Her wings are designed to dampen the sound in flight.

She is a silent hunter.

[Quacking] [Owl screeches] [Screeching] Like so many that come to the Niagara region, snowy owls are mere visitors.

But for what remains of winter, she will be the master of this icy realm.

♪ Winter brings gale-force winds... [Thunder] generating ocean-sized waves... ♪ some reaching 25 feet or more.

♪ The Great Lakes are among the most dangerous waters in the world.

Proof of their treacherous nature lies below the surface.

♪ Over 6,000 ships litter the bottom of this inland sea.

♪ Mariners have nicknamed this zone of death and destruction Graveyard of the Great Lakes.

♪ Yet despite the danger, some see these storms as opportunities.

Sam: When surf season starts up, we're looking for the absolute worst weather possible.

Narrator: With high winds in the forecast, Sam and his brother head into the storm.

♪ Sam: More than 50% of the people we meet think we're absolutely insane.

Narrator: You have to have thick skin to be at home in these waters... and an adventurous spirit to embrace it.

♪ ♪ Niagara Falls is truly a natural wonder... a unique and diverse ecosystem unlike any other.

♪ Niagara is also a place made special by those who come here every year to admire its beauty.

[Indistinct chatter] Once a year, a spectacle unfolds entirely of our own making.

The Winter Festival of Lights.

Niagara Falls transforms itself into a picture-perfect kaleidoscope of colors.

♪ Tonight is New Year's Eve.

Crowd: 8, 7, 6, 5, 4, 3, 2, 1!

[All cheering] ♪ Narrator: It is the celebration of a new year.

And the celebration of a remarkable natural wonder.

[All cheering] Narrator: Winter finally pulls back her icy coat... and welcomes the dawn of a new season.

[Birds chirping] The forest welcomes the awakening of new life.

♪ Born of a vast inland sea... this is a world in perpetual motion... made each day anew.

♪ And for all who call this region home, Niagara remains a place of infinite splendor and endless fascination.

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

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