It's called the Big Empty,
an immense,
high desert that stretches across
eleven western states.
It's a sagebrush wilderness,
so vast, it resembles an ocean.
It's a land of travelers
who find refuge in winter
and a rich green nursery in spring.
But one creature relies on the sage for everything --
for food, for shelter, and a grand setting
for the performance of a lifetime --
the greater sage-grouse.
Grouse seek clearings where they compete for attention.
And they get it.
And suddenly, from underground burrows
and rocky outcrops,
along the highways of the constant wind,
the sage is a sea of possibility,
an open range...
And wild and anything but empty.
On an icy plateau,
a lone performer takes the stage.
In a deep freeze with 40 mile an hour winds,
he begins his ancient display.
His plumage is designed to dazzle.
Key to his success is to stand out in this vast expanse.
His home is often called the Big Empty,
but that couldn't be farther from the truth.
Those who look closely
will discover a landscape full of life.
On this stage, the struggle for survival
has played out for millions of years,
but change is on the horizon,
splintering what remains of the wilderness,
forcing those who call this home
to face an uncertain future.
In this rugged landscape, life has found a way to thrive.
Winter is over,
but a final blizzard forces itself onto
the first days of spring.
The locals here are accustomed to extremes.
They've adapted to survive where others cannot.
One in particular,
the greater sage-grouse, is found no place else.
Despite the late snow,
the lone performer begins his spring ritual.
Instinct tells him it's time.
His story actually began three years ago
with his father on a nearby stage.
He's not alone.
Males from across the range are arriving
to spar for female attention.
Their elaborate display
has only one purpose --
to pass on their genes to the next generation --
but self-promotion on an open stage is risky.
This is the heart of the West,
an ecosystem that once stretched
500,000 square miles across North America.
Today, only half of that remains.
At altitudes above 3,000 feet, it's considered high desert,
a place of scarce water.
60% of it comes from snow,
and most of that is carried to outlying rivers.
As the days lengthen, temperatures rise,
and a transformation takes place.
The melt reveals a sea of sage.
Sage is the anchor of the high desert.
Without it, the land would be a dust bowl.
These twisted shrubs can live 140 years.
Extending for hundreds of miles in every direction,
they're the foundation of this wilderness.
The wildlife here
has evolved with the sage for over two million years.
With a new chick to feed,
the golden eagles constantly look out for prey.
In open country,
these powerful raptors can hunt almost anything,
allowing them to raise families
across much of the northern hemisphere.
Since the first European settlers moved westward,
this land has been traversed
and cursed by travellers.
It's the place in between, the Big Empty,
through which one must pass to arrive somewhere else.
Only those who linger will witness
the intricate balance of this land.
The sagebrush steppe is a geological masterpiece.
These basins were shaped and lifted
by the same forces that built the surrounding mountains.
Today, ridges protrude like islands.
The rocks, carved by eons of erosion,
provide a perfect nesting perch.
It will be months before the chick can fly.
For now, she watches the world from up high.
On the flats below lies the home of the grouse.
They've spent the last eight months hiding.
But in early spring, their genetic imperative
draws them to these open stages.
Years of thaw and evaporation
have left patches of salty sediment.
The grouse use these clearings as leks,
gathering sites for their mating ritual.
Puffing their yellow air sacs,
they make a series of popping sounds
to intimidate the other males.
They used to display in the hundreds.
Today, they gather in the dozens.
Our male has been practicing his display since February.
He's put on weight over the winter.
Testosterone has enlarged his neck pouch
for the breeding season.
He fills a balloon inside with more than a gallon of air,
fans his tail, and squeezes the air sac.
As other males approach, the contest begins.
They only have a few weeks before the females arrive
to establish their dominance and a territory.
Pairs square off,
facing just past each other,
and then...
Fights are ferocious and frequent.
Males battle dozens of times a day.
Serious injuries are rare.
Mostly it's a battle to exhaustion.
The chance to mate only comes once a year,
and for grouse, years are limited.
Most males won't live more than four years.
They might well only get two chances to breed,
if they survive.
They'll be back at daybreak.
Survival is pointless without offspring.
Sage has sustained pronghorn
and mule deer through the winter.
With the melt,
the deer head off to their summer ranges in the mountains.
Pronghorn migrate within the sage.
These antelope are the fastest sprinters on the continent,
adapted to outrun the American cheetah.
The cat is long extinct, but the pronghorn still run.
They've been here for millions of years,
unlike some newcomers.
We're actually late-comers in terms of evolution,
and many of us have failed to last
in this exposed environment.
The native wildlife evolved with this landscape,
but their ancient migratory paths
are now splintered.
Mule deer, adapted for life
in the mountains, can jump smaller fences.
Pronghorn evolved on the open range
with few obstacles.
If there's no way under, they must leap.
Eagles have few boundaries.
The parents are now hunting for three.
Their eaglet will rely on them for the next six months.
Roads turn the mule deer migration
into a windfall for eagles.
When temperatures warm, the high desert comes to life,
revealing the diversity hidden through winter.
Hibernators surface from below.
Prairie dog families excavate new tunnels,
preparing for their pups.
A badger digs her underground den
where she'll soon give birth.
Short-horned lizards emerge with the ants.
The timing is critical,
since ants are their sole source of food.
And jackrabbits have shed their winter white,
confirming that spring has arrived.
The sage sea is filling with new life,
and everyone is hungry.
Wind is a constant in the high desert.
Facing steady speeds of 20 miles an hour or more,
the sage hugs the ground.
Only the rocks have stood up to the desert gales,
but over the eons,
even these have been scoured and sculpted.
Each year, migratory birds fly hundreds,
even thousands of miles to raise their young here.
They synchronize their arrival with the emergence of insects.
Some return to the exact same spot year after year,
finding their small crevice once again in this vast expanse.
For cavity-nesting birds,
rocks are the trees of the desert.
Bluebirds use holes like these in place of hollowed trunks.
Despite their brilliant blues,
females pick their mates mostly for the quality of his shelter.
The tiny American kestrel is the only falcon
in North America that uses cavities.
With their ultraviolet vision,
they track rodents by following their urine trails.
Rock wrens nest between stones on the ground.
They're highly adapted to life in the desert.
Like many other desert-dwellers,
they get all their water from the insects they eat.
Once the sun falls in the desert,
temperatures can drop by 40 degrees,
and creatures of the day
give way to those of the night.
At daybreak, our male is already at the lek.
He's been here every day for the past three weeks.
Weaker males have dropped out,
leaving only those with staying power.
He takes his place on a small rise,
a spot he's fought hard to secure.
A female steps onto the lek and begins her inspection.
The males inflate, tails spread,
but beyond displaying, they're powerless.
It's the female who holds the cards.
To a spectator, males might all look alike,
but the females can clearly distinguish.
Just what they're searching for is not altogether clear.
Is choice based on looks or sound,
stamina and strength?
Despite decades of study, the jury's still out.
We do know that successful males
display precisely and repeatedly,
taking their cues from the females.
They know not to be too aggressive
and to mount only when invited.
Surprisingly, most males never get a chance to mate.
Nearly all the females select
only one or two males on the lek each year.
In fact, 3/4 of females often choose the very same male.
Clearly they see something
they want to pass on to their offspring.
A female stands beside our male, sizing him up.
She approves and gives her solicitation display.
The best males can mate,
fight off competition,
then mate again all in under a minute.
Scientists recently counted a single male mating 37 times
with 37 females in 37 minutes.
Once they've bred,
the hens have no further need for the male.
They'll raise their offspring alone.
Fanning out across the landscape,
the females head away from the lek.
Too many predators are drawn to these open stages.
To find a safe spot for her eggs,
a hen might travel as far as ten miles.
It's easy to assume there's plenty of open space for grouse,
but here in the desert,
resources are scarce and far apart.
Grouse need to track down food, water, and shelter,
which could be 30 miles in any direction.
This first-time mother has much to consider as she searches.
She needs to build her nest
away from rocks or fences where raptors can perch,
and she needs cover, a place well-hidden by sage
and grass.
Grass also acts like a sponge, holding water for
the smaller plants and insects that her chicks will eat.
Here on the range, grass is in high demand.
For millions of years, bison fed on these grasses.
Today, livestock graze.
While bison roamed freely, livestock is managed,
moved from parcel to parcel.
If allowed to overgraze,
the grasses take years to recover.
Settled on her nest,
the hen is nearly impossible to spot.
She's built her nest in a shallow depression
beneath the sage, lining it with grass and leaves
and dozens of her own feathers.
Now she and her eggs must wait.
Unlike grouse, ravens are adaptable,
nesting in a variety of places.
They typically build on rock ledges and in trees,
but they also take advantage of manmade perches
like windmills and storage tanks.
They can eat almost anything, including human garbage.
Their ability to conform
gives them an edge in this changing landscape.
Cliff swallows also build nests in manmade structures,
but here they nest in sandstone cliffs.
They've just arrived from South America,
returning to the same spot as last year.
They're hard at work on their hanging village.
Males and females work together,
mating during the process.
They swoop down to the river
and fill their mouths with mud,
then return to their nest.
With a quivering, they add another brick.
A new home requires over 1,400 trips to the mud.
Great-horned owls share these cliffs.
Like golden eagles, they breed in winter
because it takes months to raise such large offspring.
Chicks need to learn how to fly and hunt before the first snow.
They're the most widespread owl in North America
since they nest almost anywhere.
They also adjust their diet to their surroundings.
Here they hunt the sage for rabbits, prairie dogs,
and birds.
Ravens also feed their young a wide variety of prey.
After discovering another bird's nest,
the male delivers a meal of eggs.
Down in the sage,
the scene reveals the source of the feast.
Our hen has lost her clutch.
40% of grouse eggs are ravaged before they even hatch.
There's nothing a hen can do but move on.
She can wait for next year or try for a second clutch.
On the lek, males are still displaying.
They return every day,
hoping for females who've lost their nests.
Our hen has returned,
but there's little time.
Her second clutch will need to hatch
while there's still plenty of food for her chicks.
She sifts through the males, searching,
for the very same male she chose before...
And finds him.
In a world where passing on his genes means everything,
this male has succeeded.
The success of a male grouse is not measured by his years,
but by his offspring.
Our hen is on the search again,
but this time, there's even more urgency.
For second clutches,
nature makes up for lost time by shortening the gestation.
She'll start laying in just a few days.
She scans the landscape.
To the untrained eye, it's an ocean of gray-green,
but to her, there's nuance in the sage,
subtle distinctions in the grasses between the brush.
The next generation depends on her judgment.
She's found an area with thicker cover.
She chooses a spot and settles in for the wait.
If she's chosen well,
she'll hide here for up to a month.
Unlike ravens and bluebirds,
grouse are tied to unbroken expanses of sage.
Without it, the species would cease to exist.
The sagebrush sparrow would also disappear.
Each year they return here to lay their eggs.
They breed nowhere else.
The sage thrasher
and brewer's sparrow do the same.
Though their songs are beautiful,
their feathers are drab, to blend into this landscape.
Without the sage
and the nursery it provides, these species would be lost.
Sagebrush is a nursery for plants as well.
While it's toxic for most animals to eat,
it's actually called a nurse plant,
because its shade and roots help other plants grow.
Sage survives in this arid environment
through deep roots that reach to the water below.
Like water, most resources in the desert
are locked well beneath its dry crust.
Coal, uranium, gas, oil.
We've drilled down like deep roots
to tap these resources.
With our ever-increasing demand for energy,
extraction has intensified in the high desert.
As wells, pipelines, and holding tanks proliferate,
the sage sea is becoming more and more fragmented.
This one gas field was once
a migratory corridor for pronghorn
and prime habitat for sage grouse.
Many of the changes we've made here
will remain long after the resources are tapped out.
This is not an ecosystem that regenerates quickly.
The hen has laid eight eggs, a full clutch.
For the next month, she'll rarely leave the nest.
Every few hours,
she carefully rolls her eggs to even out the temperature.
It also prevents the chicks from sticking to their shells.
[Thunder]
Throughout the summer,
electrical storms roll across the desert,
often shedding only drops of water.
The storms bring more bluster and spark than rain.
Native plants have adapted to these electrical storms.
But while sage is fire-resistant,
highly flammable "cheatgrass" has invaded the desert,
bringing a new threat.
Wildfires, driven by fierce winds,
burn thousands of square miles of sage each year.
After the storm,
neighboring thatching ants repair their roof.
It's a happy fluke when meals deliver themselves.
A burrowing owl stands sentry.
She and her mate guard their nest,
a repurposed badger hole.
Here in the desert,
life takes advantage of every opportunity.
Weighing only five ounces,
they're tiny for owls.
Great horned owls are 15 times their size.
This couple has nine chicks to raise.
They're excellent hunters,
specializing in small rodents insects.
With this many mouths to feed,
the parents hunt both day and night.
When fall sets in, they'll fly as far as Mexico.
It's been 24 days.
At last, there's a sign of life from below.
The first chick peers out and snatches his first meal.
Less than an hour old, he's already able to feed.
When the hen hears a badger nearby,
she moves off to distract it,
revealing another five newly hatched chicks.
They're at their most vulnerable now,
still wet from the eggs.
It's been only two hours,
and all eight chicks have hatched.
The moment they can walk, they have to feed.
They can't digest sage yet, so for the next few months,
they'll eat other plants and insects.
For their safety, as soon as they're dry,
the hen leads them away from the nest
for good.
Ferruginous hawks stay in their nest for six weeks.
Their parents harvest
a steady stream of prairie dogs and ground squirrels
from the abundance around them.
Rodents are plentiful and just the right size.
Now six weeks old,
the eaglet needs much larger meals.
Cottontail and jackrabbits are staples.
So are grouse.
[Calling]
Sensing danger above, the hen gives a warning call.
Instinctively, the chicks take cover.
She moves off, away from the brood.
They'll stay put until they hear from her again.
[Calling]
When the danger's past,
a contact call brings the family back together.
For the next month, they'll forage constantly.
In a couple of weeks,
their adult plumage starts to come in.
Soon they'll blend in with the grownups.
As long as they can find food, they'll stay in the sage.
As the summer heat dries the sage,
water is at its scarcest.
Seasonal plants, with their deep roots,
have retreated back underground,
the insects are gone, and the grouse are on the move.
They have to follow the green in search of food and water.
Natural wetlands are scattered across the high desert.
Like ribbons,
small streams trickle from springs,
creating marshes.
Wetlands are a green magnet for wildlife.
These oases host an entirely different cast of characters
than the sagebrush.
These sandhill cranes hatched at the very same time
as the grouse chicks.
While grouse couple for only seconds,
these parents mate for life.
They might spend as many as 20 years together,
migrating to and from Mexico.
This northern harrier has three mates on three different nests
somewhere down in the reeds, and each has chicks to feed.
He's been scanning the sage for prey,
but now he has his eye on the blackbirds.
Red-winged and yellow-headed blackbirds
defend their territories with a vengeance.
Their eggs lie hidden in the grass below.
The steppe, now parched,
is a hostile place for young grouse.
Over the last six weeks,
the hen has lost three of her chicks.
They've traveled miles from their nest.
What's left of the family has joined up with other grouse
on their migration to water.
But it's not a pristine marsh they're headed to.
Humans settled most of the fertile areas long ago.
For more than a century, we've battled sagebrush,
removing it so we could harness the land.
Farms and ranches have transformed
most of the wild wetlands.
But native wildlife still need the moisture,
and many manage to coexist.
Grouse are safest hidden in the sage.
On ranches and farms, short grass means less cover.
But the grouse adjust,
when the human footprint isn't too extreme.
These wetlands once supported thousands of grouse.
Despite the alteration, some still support hundreds.
Housing developments are a different story.
They leave little for wildlife.
Parts of the high desert have become some of
the fastest-growing areas in the United States.
Wide-open habitat is quickly being portioned off,
transforming the Big Empty.
Fall is fleeting in the high desert.
The days shorten, temperatures drop,
and creatures take their cue to migrate.
The rock cavities, recently full of life,
are now empty.
The songbirds have headed south for the winter.
The eaglet has finally left the nest.
She's still testing her wings.
The marshes have browned
and the grouse are headed back to the safety of the sage.
The chicks are old enough now to eat its leaves.
This will be their only food for months to come.
As autumn settles on the range,
winter has already arrived in the mountains.
The mule deer have been here since spring.
It's here that they gave birth, but food is scarce now.
They begin their descent, leading their young.
Born in the mountains, this is their first migration.
The adults will teach them to navigate rivers
and fences.
They return just as the first snow falls.
As harsh as winter is on the plains,
it's milder here than in the mountains.
Both mule deer and pronghorn
will feed on sage through the winter.
This will be their refuge for the next five months.
Half of the grouse born this year
didn't make it through the fall.
Three of our hen's chicks survived.
While winter looks brutal,
it's a time of plenty for the grouse.
They'll shelter in the sage
and grow stronger on their diet of leaves and snow.
In this way, the seasons pass,
just as they have for hundreds of thousands of generations.
It's been two years,
and one of the chicks has taken his father's place.
He's a strong male,
already defending a territory for his spring display.
In the short time since his father dominated his lek,
the horizon has changed.
A drill rig has sprouted in the distance.
Only two years ago, it wasn't here.
The howl of the wind
now mingles with the hum of machinery.
200 years ago,
there were as many as 16 million sage grouse.
Today, there may be fewer than 200,000.
This land, which might at first appear empty,
is far from just a place in between.
It's 140-year-old sage brush
and a constant wind that carries its scent.
It's the clatter of antlers
and the beating of wings as migratory birds come and go.
It's a soaring raptor
and a rare performer that takes a chance each year
on the open range,
an ancient stage where evolution has slowly shaped
the lives of those who live here.
It's a once-vast wilderness, no longer untouched,
with a future as uncertain
as the survival of an uncommon bird.
To learn more about what you've seen on this "Nature" program,
visit pbs.org.