Original subtitles

Big Bend National Park.

Male desert bighorn sheep prepare for battle.

Big Bend's monsoon season is the perfect time to breed.

The strongest males will pass on their genes

to the next generation.

The arrival of a female ratchets up the tension.

Before the fight, males test their opponent's resolve.

As heat and humidity

build across one of America's last great wildernesses,

the pressure increases.

Only to release in a single strike.

Months before the monsoon,

Big Bend National Park is peaceful.

A wild sanctuary deep in the heart of Texas.

Established in 1944,

it's 800,000 acres

of mountains, deserts,

and rivers.

A challenging place to call home,

but the park's spectacular range of habitats

provides opportunities for plants and animals,

creating a surprising web of life,

with more species of birds, bugs and cacti,

than any other national park in the United States;

making Big Bend the perfect home

for one of the park's most hardworking parents.

The roadrunner, a true survivalist.

She's fully prepped for life in this remote corner of Texas,

hunkering down in a prickly pear cactus.

With two chicks on the nest and four more on the way,

it pays to be tough.

Right now, there's calm.

But for a roadrunner mom,

the peace and quiet doesn't last long.

Her chicks are hungry.

Fortunately, she's raising kids in a place

where there's plenty to eat.

But it's still a grueling routine.

Leave.

Catch prey.

Return.

Feed chicks.

That should do it.

Leave.

Catch prey.

Return.

Feed chicks.

It helps that roadrunners eat almost everything

from spiders to scorpions.

Mom is also a super-quick hunter

with a top speed of 20 miles an hour.

With hundreds of roadrunners living here,

it's a good thing Big Bend

has an amazing biodiversity of bugs.

Not that the chicks seem to appreciate it.

As they grow, their appetites cannot be stopped.

Time for dad to go big.

This lizard may be fast, but the roadrunner is faster.

A supersized meal almost as big as the chick?

No problem!

Surely this will fill them up.

Thanks to the bounty of food available in the park

and the tireless efforts of doting parents,

peace and quiet return.

Or, maybe not.

Nearly 6,000 feet up in the mountains,

another mom has a huge challenge.

A female black bear has spent the winter

in a high mountain cave.

She needs to teach her cubs to survive in the park.

With little to no food or water for months,

the stakes are high.

But they're living in a special place.

Big Bend is the only national park

with an entire mountain range inside its borders,

the Chisos.

Named for their previous inhabitants

and once home to the Mescalero Apache

and the Comanche tribes,

the mountains are a sky island oasis.

40 square miles of peaks, up to 8,000 feet,

loom over the hot desert below.

At the height of summer, monsoon storms

can dump nearly a year's rainfall in a few months.

Right now, the monsoon is a long way off,

but the Chisos do something incredible.

They catch the rains and store them for year-round use.

Water slowly releases from deep in the mountains

into precious spring-fed pools.

Attracting critters of all types.

And all colors.

The key to survival in a desert is a reliable source of water.

And mom knows exactly where to find it,

thanks to her mom,

who taught her about the hidden oases in the Chisos.

It's the cubs' first visit to this magical place.

Every day is a school day.

Today's lesson is all about water.

They've never tasted or seen so much of it.

Mom relaxes in the spring,

but for the cubs, it's playtime.

The fun has to come to an end eventually,

but mom has another lesson for her eager students.

How to scratch that itch.

Mom shows how it's done,

rubbing off her winter coat

and leaving a scent behind,

signaling her presence to other bears in the park.

Mom made it look easy,

but the cubs will need a lot more practice.

For the bear family,

the Chisos Mountains provide water and a cool refuge,

but down below on the desert floor,

life in the park has more extreme challenges.

Big Bend protects a vast and pristine area

of the Chihuahuan Desert,

the largest in North America.

Early Spanish settlers called it, "El Despoblado,"

a desolate and empty land.

If your home is tough,

sometimes you've got to be tougher.

And one animal is the ultimate desert survivor.

The Texas horned lizard.

He's everything you would expect from a desert veteran.

Perfectly camouflaged.

And searing hot is just how he likes it.

Once widespread across Texas,

the horned lizard is in decline.

Agriculture and urban development

have robbed this reptile of space.

Protected areas like Big Bend National Park

are vital for his survival.

He's on the hunt.

And ants are on today's menu.

Just like the last meal, and the next.

In fact, ants are pretty much all he eats.

These small snacks are all he needs to survive.

But the ants won't surrender without a fight.

These are harvester ants, packing super-strong jaws

and one of the most toxic insect venoms ever discovered.

A defensive stinger in the back

contains a neurotoxin so strong,

that with enough stings, these ants could kill a human.

But this lizard's hunting technique

combats the ants' deadly defense.

All he has to do is hold his nerve.

His timing has to be perfect.

Not now.

Not now.

Not even now.

If the ants mob him, he'll have to retreat and go hungry.

One false move, and it's game over.

For the horned lizard, getting a meal requires

military precision and patience.

He picks a target and takes aim.

It's now or never.

His tongue shoots forward at the speed of a bullet.

It's all over in a fraction of a second.

A precision weapon,

avoiding the ant's bite and deadly stinger.

The sticky tongue flicks it into his stomach in one move.

The ant drowns instantly in thick mucus on the way down.

Any slower, he'd get a toxic sting to the mouth.

As the desert heats up in Big Bend,

the challenges keep coming,

and the Texas horned lizard will deal with them head on.

Spring moves into summer, and the Texan sun

bakes Big Bend National Park to a crisp.

It can reach well over 100 degrees,

and the monsoon rains are more than a month away.

Across the park, everything is dry.

The reserves from last year's rains run low.

And the bear family desperately digs

for the last drops of water.

On the desert floor, conditions get more brutal by the day.

Without rain, wind whips up dust storms.

Big Bend transforms into a hostile place.

With such extreme heat, the park's main river system

becomes a vital and rich ribbon of life.

The Rio Grande forms the park's southern boundary with Mexico,

connecting millions of acres of protected land

on both sides of the border.

Overuse from agriculture upstream

and a changing climate

have reduced the once mighty river's flow.

Across the park, rivers run dry.

Each remaining water source holds the key to survival.

Last summer, this place had barely a trickle.

But now, something truly surprising has appeared.

An oasis of life.

But it's no miracle.

It's an impressive feat of engineering.

Meticulously constructed by one determined critter.

A beaver.

For the past few months,

she's been building a dam

on a small tributary of the Rio Grande.

It's taken months of hard work, but night after night,

she's transformed a tiny spring into a desert paradise.

Around 200 beavers live in Big Bend National Park.

But it takes a pioneering spirit and perseverance

to overcome its harsh conditions.

There is another reason

this beaver has been working so hard.

She's building a future for her family.

Her home also provides water for other animals in the park,

attracting life from miles around.

But the beavers' Big Bend paradise

is about to be put to the test.

The first sign of the coming monsoon

lights up the Big Bend sky.

Warm, moist air from the Gulf of Mexico

pushes further west into the park.

It collides with the Chisos Mountains.

Immense storm clouds form,

ready to break.

The monsoon is close.

Although the storm passes 100 miles to the north,

in Big Bend, it's enough to create

one of nature's most destructive forces...

A flash flood.

In just hours, the river's flow can increase more than 1,000 times.

The beaver's dam is destroyed.

Months of tireless construction

are no match for the power of floodwaters.

The beaver's desert dream has become a nightmare.

It was a brave move to build a dam here.

But this is Texas.

It will take more than a flash flood

to crush the beaver's spirit.

The dam just needs to be bigger.

While the coming monsoon proves problematic for some,

for others, it provides a world of opportunity.

When the rains arrive, plants unfurl and burst into life.

Temporary lifesaving pools spring up across the park.

And on the steep cliffs above the desert,

the monsoon triggers the most dramatic time of the year

for a mighty beast...

The desert bighorn sheep.

Their presence alone is cause for celebration.

60 years ago, the bighorns were gone;

killed off from overhunting and disease.

But since the 1980s, international efforts

have restored them to their rightful place.

With feet made to climb,

they are perfectly adapted to the rocky terrain.

Able to scale near-vertical cliffs with ease.

The monsoon approaches.

Males zero in on the scent of females ready to mate.

There is a strict hierarchy in place.

Rams younger than seven rarely take part.

Competition is so fierce

that one-on-one combat can last over 25 hours.

But before they put their horns to the test,

contenders taunt their rivals.

Withstanding pain is a test of endurance.

But it's a waiting game.

Who will break first?

The monsoon rains are edging closer,

and the atmosphere is electric.

Tensions are high until fights break out.

All the fighting has a purpose.

If the winning males breed now,

their newborn calves will have the most nutritious green shoots to eat,

brought on by the rains.

A finely tuned survival strategy

for the toughest of Big Bend survivors.

The monsoon has finally arrived.

It's the moment the park has been waiting for.

The desert soaks up the life-giving rains.

For plant life in Big Bend,

it's welcome relief,

and for the animals, too.

Big Bend's veteran has another awesome desert adaptation.

He flattens his body out to catch as much rain as he can.

A useful skill in a place

where rains are patchy and unpredictable.

The monsoon weather system

is the defining feature of the park.

All life in Big Bend depends on it.

Storms can be intense, but there are places here

that will see a whole year pass without receiving any rain.

So the Texas horned lizard

needs to catch every precious drop.

As fast as they arrived, the rains pass,

and Big Bend dries out under the harsh Texan sun.

But the horned lizard can find and make use

of any water source, no matter how small,

simply by standing in it.

His waterproof skin has a network of capillary channels

between the scales, directing water straight into his mouth.

Tiny jaw movements pull water in for drinking.

It's another amazing adaptation for Big Bend's toughest lizard.

After the rains, plants race to flower

and reproduce while moisture remains in the soil.

It's time to celebrate

as Big Bend puts on a show in full color.

Prickly pear fruit ripens...

Providing an energy-rich treat for insect life.

A leaf-footed bug doesn't travel far.

The prickly pear cactus is both his home and food supply.

Most of the year his meals are a little tough,

but for a few weeks after the rains,

it's easy picking.

Juicy, soft, delicious fruit.

Other animals have a liking for cactus fruit, too.

The bear cubs are growing fast

and learning about all the good things

Big Bend National Park has to offer.

Even the slower residents rush to get a taste.

For the box turtle, it's a fruity feast worth waiting for.

In the harsh Chihuahuan Desert,

there are still times when Big Bend provides.

One plant here is a beacon of life in the park.

An intimidating beast with a rich history.

The agave.

Once a building material and food source

for the indigenous people of Big Bend.

Now it's the main ingredient in tequila and mezcal.

And Big Bend would not be the same without it.

The agave doesn't seem to do much.

It takes its sweet time to build up reserves.

Sometimes waiting up to 50 years.

Taking energy from the sun and water from the monsoon rains.

All the while getting bigger, stronger,

and sharper.

Then one day, something magical happens.

After decades, the waiting is over for the agave.

All that stored energy erupts,

sending a stalk 30 feet into the sky.

The plant's final act,

using its last reserves for one purpose, to reproduce.

Flowers bloom, but they need to be pollinated,

and they're going to need help.

Hidden inside the agave's flowers is sweet, sweet nectar.

The astonishing variety of flying critters in Big Bend

means it doesn't take long for word to get around.

The first wave of pollinators arrive.

Some come for nectar;

others for nectar feeders.

But all will take a little pollen with them from plant to plant,

helping the agave reproduce

and maintain its presence in the park.

In Big Bend the secret to success

is making the most of every opportunity.

And the agave has become a star attraction.

After sunset, the agave ramps up nectar production.

Its flowers now fully open, this is the time

for the agave to spread its pollen far and wide,

as the second wave of pollinators descend.

The five-spotted hawk moth's

long proboscis is the right tool for the job,

ideal for sucking up nectar from deep inside.

And just like the day,

at night, predators are on the prowl.

The nocturnal elf owl is a skilled hunter.

Taking prey while they feed

and making a home in the agave's stalk.

But of all the creatures that visit the agave,

there is one that spreads more pollen to more agave plants

than any other pollinator.

The Mexican long-nosed bat.

Flying almost 800 miles from central Mexico,

they spend the summer feeding on the agave

in Big Bend National Park.

Until now, this ancient exchange

has only been witnessed by a handful of scientists.

The bat's long nose and tongue fit the flowers like a glove.

The agave and bat have evolved together

for thousands of years.

They depend on each other for survival,

and Big Bend National Park for protection.

Nights in the park attract another creature from far away.

People travel from all over the world

to experience something you can only get

in a handful of places like Big Bend National Park,

true darkness.

Here you can see across the galaxy and beyond.

Humans aren't the only ones to make the most of the dark.

But with a sturdy pair of boots and a flashlight,

visitors are welcome to explore the park at night,

which is the best time to see a particular breed of visitor...

The astrophotographer.

Big Bend National Park is at the top of their bucket list.

Surrounded by millions of acres

of protected land and wilderness,

the lack of light pollution

makes it one of the best places on the planet to film the stars.

As the world gets more crowded and developed,

dark places like Big Bend National Park

become even more precious.

And if it's your home, it's a place worth fighting for.

When the floodwaters recede,

the beaver gets back to work...

Day...

And night.

Rebuilding the dam to create a year-round waterfront home

for her family.

Beavers are found all over America,

but this beaver mom is a Big Bend veteran.

A highly skilled engineer, adapting to changing times,

determined to make a life here

no matter what the park throws at her.

As the season shifts into fall,

an early cold snap is a sure sign

that winter is just around the corner.

For the bear family, it's time to prepare.

After everything that Big Bend has thrown at them,

the best is yet to come.

Soon mom and cubs will head back to the cave

to ride out the winter,

but first, they need to put on enough pounds

to make it through.

As a final fall gift, the park lays out a feast of acorns.

Oak trees thrive in the cool valleys of the Chisos...

Creating a park paradise

vital for the survival of all bears.

Without the Chisos,

Big Bend would not support the rich web of life here.

It's what makes the park unique,

something the bears certainly appreciate

as winter approaches.

They enter a phase called hyperphagia,

eating as much as they can, as fast as they can.

And oak trees provide an all-you-can-eat acorn buffet.

The cubs have never seen a full winter.

Now, they'll learn another important survival lesson from mom,

how to make the most of every opportunity.

Some acorns are a long way up.

You could just wait underneath

and let others do all the work.

But sometimes, you got to go straight to the source.

All the tree climbing practice pays off.

Now mom can sit back and wait for the acorns to fall,

letting her cubs do all the work for a change.

A quick power nap,

and the youngsters are back at it again.

Young bears are still light enough

to climb out to the smallest branches.

Their reward is acorns adults simply can't reach.

With the energy from a final feast,

the bear family heads back to the mountains

to wait out the winter.

Their survival means more to Big Bend National Park

than they can ever know.

When Big Bend was established in 1944,

there were almost no bears left in the park.

They had all been trapped or shot.

It wasn't until the 1980s,

when a bold mother bear crossed the Rio Grande

to raise her cubs in the Chisos,

that a significant bear population

could begin to rebuild.

The park offered protection.

Their return is a reminder that this is a very special place.

A sanctuary not just for bears,

but for the entire web of life that makes a home in the park.

Big Bend is a treasured gift from Texas to the nation.

And like all of America's National Parks,

it's a gift worth holding on to.

Captioned by Cotter Media Group.