All language subtitles for Yellowstone.Wildest.Winter.to.Blazing.Summer.E03.The.Blazing.Summer.720p.10bit.WEBRip.x265-budgetbits_track3_eng

[WHIMPERING, SNARLING]

Previously, we've witnessed how animals
survive Yellowstone's Extremes.

Starting in winter,
it was well below freezing

and some animals really struggled.

Then in spring, temperatures jumped
nearly 30 degrees in a fortnight.

And wildlife had to cope with
the thaw coming three weeks early.

Now, summer is here,
and there are new challenges.

The melt water will dry out fast,
food becomes scarce,

and if there's no rain,

wildfires will threaten
to destroy the habitats animals rely on.

[SQUEAKS]

Welcome to Yellowstone's blazing summer.

So far, in 2016,

every month has been hotter
than average in Greater Yellowstone.

If the trend continues,
summer could reach record temperatures,

and push animals
to the brink of survival.

Yellowstone lies
over 600 miles from the Pacific,

and has a continental climate,

which means
summers can be relentlessly hot.

Now, at the moment, it's all
still looking quiet lash and green,

but in the coming weeks
as the temperatures continue to rise,

the vegetation will start to wither,
valleys will become dust bowls,

and lakes and streams
will start to dry up.

Wildlife must travel further
in search of food,

drinking water,
and shelter from the heat.

ARYEE: Young animals
born back in spring,

are now entering their first summer.

They are lot more mobile,
but still need to avoid danger

whilst exploring
on those unsteady lakes.

HUMBLE: For this latest generation,
the changing climate

will make their lives
even more challenging.

In spring,

the beaver family was affected
by the unusually warm temperatures.

Huge volumes of melt water
flooded into the Snake river

where the beavers had made their home
in the south of Greater Yellowstone.

Snow melting from the all the way
up there in the Teton mountains,

rushed down in a deluge,

and threatened to wash
our beaver dam away.

Beavers dam rivers
to create a series of ponds

where they live and feed,
safe from predators.

After working flat out
on emergency repairs to the dam,

the beavers just managed
to save their home from the flood.

Now in summer, the family
could face the opposite challenge,

too little water in the river.

I've come to meet wildlife
cameraman, Jeff Hogan,

who's been following the beavers.

ARYEE: Hey, Jeff.

HOGAN: Hey.
ARYEE: How's it going?

Hey, there you are. How you doing?

ARYEE: Jeff was filming
great grey owls in spring.

Now, he'll use his specialist skills
to study the beavers,

and has installed an infrared camera
inside their lodge.

[SQUEAKS]

I got something to show you.
There's a bit of a surprise.

ARYEE: This footage looks like the
male and female I saw here in spring.

See, it's a couple of big fat beavers...

Yeah.

ARYEE: But then, something unexpected.

Oh! Oh, my gosh! [LAUGHS]

ARYEE: That's so adorable.
HOGAN: That's a great shot.

-Oh, my goodness. No way.
-That's amazing.

ARYEE: Oh, man, they're so adorable.

ARYEE: Baby beavers are called kits,
and mum has given birth to three.

HOGAN: I would say they're probably
about ten weeks of age maybe.

ARYEE: Kits are precocial,

which means they're mobile
and quite advanced from birth,

emerging with a full coat of thick fur,
sharp, chisel-like teeth,

and the characteristic flat tail.

This they use as a rudder to steer
when swimming,

which they can do
within a day of being born.

But these three
still rely on their family,

to bring them food
from outside the lodge.

HOGAN: I got another clip for you.

ARYEE: Oh, look at all that willow.

This adult beaver just brought in
three or four branches, all bundled up.

And that little young ones
will just jump on this.

They'll gobble out right down.

ARYEE: At ten weeks old,

these kits has stopped drinking
their mother's milk.

They now have an adult diet.

In summer, the ponds that beavers create
become their vegetable gardens.

The slow warm waters
create optimal conditions

for edible plants to grow.

Mum, dad and last year's young
are working overtime

collecting food for the kits,
and keeping the moat to clean

by washing grassy bedding.

In a matter of days,
the kits will leave the lodge

and learn to forage for their own food
whilst avoiding predators.

Around 50% of beaver kits
don't survive their first six months.

It's a critical time for this family.

And Jeff will be following them
every step of the way.

HUMBLE: Across Yellowstone,
our teams have been documenting signs

that an early spring thaw
kick-started an early summer.

As icy melt waters
flowing of the mountains subsided,

streams warmed rapidly in the sun.

And the surface of the water
started to dance.

Rising water temperatures trigger
mayflies to hatch in their millions.

These conditions are the starting pistol
for an important event.

The arrival of cut-throat trout.

Many have spent the winter
in Yellowstone's deep rivers and lakes,

but migrate upstream to feed on mayflies
and spawn in these shallow waters.

Every year,
the arrival of this protein rich fish

creates a feeding bonanza
for river otters,

mink, bears, and birds of prey,
like eagles and osprey,

over 20 different species
of birds and mammals.

This year, the early snow melt
have given these predators

a head start to flatten up.

ARYEE:
While summer temperatures have created

a frenzy of activity on the rivers,

Yellowstone's low altitude grasslands
are eerily quiet.

In spring, herds of elk and bison
were feeding here.

But they've moved on,

as the green vegetation
withers in the heat.

What the locals call
"The brown up has begun."

Over the course of just a few months,
this ground has gone from being covered

in feet of snow to lush grass,
which is now scorched, died away,

and has a very little nutrition.

So grazing animals like bison and elk
need to move further up the mountains,

in search of green shoots.

ARYEE: As the summer continues,
the brown up will creep higher.

Bison and elk must keep moving.

By July, bison have arrived
at summer grazing grounds

on Yellowstone's high plateau.

This is the only time mature males
and females come together,

and herds can reach a thousand strong.

Scientist think this summer, the bison
will look particularly impressive,

after an abundance of grazing
during the warm spring.

So Kate's gone to check out
what kind of condition they are in.

[GRUNTING]

HUMBLE: Oh, my goodness!
What a magnificent beast.

The male bison at this time of year,

are truly...
Just they are in their prime.

Bulls have piled on
up to 150 kilograms of fat and muscle,

and now is their chance
to start throwing that weight around.

July is rutting season,
when males duel for the right to mate,

and this year's favourable
conditions mean it will be fierce.

The largest contenders
could be tipping the scales

at nearly a ton.

You may think,
"Isn't it a little bit early for sex?"

I mean, you know, it's the summer,
they should be chilling out,

but remember,
the bison are the first to give birth.

Think back to the spring,
the first calves we saw,

they were bison calves.

Female bison have
one of the longest pregnancies here,

lasting over nine months.

So, to time the birth of calves,
with the start of next spring,

these males need to get on with it.

This male bison found himself
the perfect dust bath.

And, at various times,
throughout the day,

he will roll in it.
He will cover himself in dust,

he'll pee in the dust and roll in that.

Just to make sure that he smells
as virile and ready for it as possible.

[GRUNTING]

Wallowing in dust baths
is a show of strength.

Each male competes to churn up
the biggest dust cloud,

and intimidate its rivals.

But when two heavyweights
won't back down,

they go head to head.

Heavily muscled necks and thick skulls
covered in a mat of dense hair,

help absorb the colossal forces
of each collision.

Only the winner earns the right to mate.

This ensures the strongest genes
will be passed on.

Whilst I've been following
herds of prey animals on the plateau,

our camera crews are at lower altitudes

on the trail of Yellowstone's
top predator, the wolf.

Over 500 wolves roam across
Greater Yellowstone.

The mild winter and spring
caused many packs to go hungry,

as the prey was well-fed
and could outrun the wolves.

In summer, the stakes are even higher
because there are young pups to feed.

In the south of Greater Yellowstone,

biologists have been studying
one wolf pack

that seems to be defying the odds
and thriving this year.

The Pinnacle Peak Pack.

This photo was taken
during an aerial survey.

It reveals the pack has eleven pups.

Unusually, two females
have given birth this year,

a sign this pack is doing well.

All the adults take it in turns to hunt,

and return to the den sites
with meat for the pups.

But the elk that make up
the majority of wolves prey,

have moved to higher grazing grounds.

The biologists have been observing
how the pack finds enough food

for all 11 pups.

They've directed wildlife cameraman,
Charlie Hamilton James,

to an area where they've seen
remarkable behaviour.

They think the key
to the wolves success here,

could be down to human activity.

[WHISPERING]

-See it?
-[ENGINE STOPS]

Uh... How's she gonna let me get out?

I'm gonna give it a go.

Bear with me on this.

[DOOR OPENS SLOWLY]

How beautiful is that?

She can smell me,
my scent is going straight at her.

She knows I'm here.

She's not bothered at all.

HUMBLE: In all his 20 years of filming,

Charlie has never been
this close to a wild wolf.

This female
is from the Pinnacle Peak Pack.

And something has drawn her here.

The grass is still green,

because it's being watered
over the summer to improve grazing.

[SNARLING]

You see the sprinklers behind her,
'cause they're watering the grass.

This creates amazing habitat
for ground squirrels.

It's just tons of them.

HUMBLE: A huge colony of grass-eating
winter ground squirrels

is exploiting this artificial oasis.

Usually, by mid-July, the grass
would be turning brown and inedible.

The squirrels would have started
entering the burrows to hibernate,

but not here.

This female wolf
has spotted the chance of an easy meal,

and it's closer to the pups
than the large elk herds, 20 miles away.

[SQUIRREL SQUEAKS]

They need these ground squirrels,
'cause they're tied to their territory.

They got pups here,
they can't go anywhere else,

so they have to find food around here.

Just to survive,
and keep those pups alive.

HUMBLE: But catching
these burrowing rodents is tricky.

They spend much of their time
looking for danger.

Balancing on their hind legs
to see over the tall grass.

The squirrels also have a range
of alarm calls for different threats.

[SQUEAKING]

A trill means
it's a ground based predator.

[SQUEAKING]

The entire colony
dive for the safety of their burrows.

She's on it. She's on one. Oh!

HUMBLE: This female
is putting in a lot of work,

but without any reward.

Oh, there's another one there again,
there's one running.

Ah, where is it, where is it?
Long way off.

HUMBLE: Another pack member
may help turn the tables.

Wolves real strength
is when they hunt together.

JAMES: There's another one.
[LAUGHS]

Look, there's another wolf.

I don't know which one to film then.

[SQUEAKING]

HUMBLE: The ground squirrels
can't watch all three wolves at once.

And these new comers are also trying
a different hunting strategy,

to outwit their quarry.

[SQUEAKS]

There's a lot of activity,
and then they'll lie down,

and you'll think, "Well,
why are they suddenly lying down?"

It's part of their hunting strategy.

You just lie down, and essentially
just wait for the ground squirrels

to come up to them.

You know, that's so dozing...
A ground squirrels comes up,

and they just leap out and grab it.
[LAUGHS]

HUMBLE: It's working.

[SQUEAKS]

Even the original female
is having more luck.

JAMES: With animals,
you get these peak moments of activity,

and they last for few days or few weeks,
and then they're gone again.

And it's incredibly lucky
that we've been able to be here

for this particular period
of peak activity.

I've never seen it before.

I don't know if it'll ever happen again
but it's amazing to witness it.

HUMBLE: These wolves
have used all their intelligence

to exploit this situation.

The food will increase
the pups chance of survival.

[SQUEAKS]

And more wolves
means a stronger pack next year.

ARYEE: It's early July,

and no rain has fallen this month
at the Snake river,

but the beavers have their home.

This, combined with the early snow melt,

means that the river
is running 20% below its average.

If the level of the beavers main pond
drops too low,

it could expose the entrance
to their lodge,

which is usually under water.

And this would make them
easy pickings for predators.

Jeff is watching them closely
to see how they react.

HOGAN: Oh, look. Wow! That's mum.

ARYEE: And it looks like mum
has made an executive decision.

She's got one of the kits in her mouth.
She's heading towards the dam.

ARYEE: She's moving one of her kits
out of the pond,

maybe to search for a new home.

HOGAN: This is incredible.

And there they go.

I'm gonna go chase 'em.

ARYEE: Scientists have observed
beaver families relocating,

but Jeff has never witnessed it
in 20 years of studying them.

Out in the open, kits are vulnerable
to predators like bald eagles.

It's a tense moment
for mum and her young.

Here they come.

ARYEE: The beaver family's
territory is large,

with fives dams and pools
along this river.

HOGAN: She's gonna crawl over
this next dam.

[GRUNTS]

ARYEE: After travelling
more than 350 metres,

and crossing three more dams,

Jeff films her mum leading her kit,
up a small channel,

that comes off the main river.

They're gonna climb
right up through this cascading stream,

waddling up through the stones...

You can see that the beavers don't do
quite so well in land,

especially this river rock.

They do so much better in the water.

Unreal, never seen this... Ever.

And there they go.

ARYEE: Later, at night,
Jeff checks his camera in the lodge.

Let's see.

ARYEE: It reveals
mum has moved all the kits,

and the whole family
has abandoned their home.

Jeff is now on a mission
to find out where the beavers have gone,

if the kits survive, and whether
this huge gamble will pay off.

HUMBLE: Whilst the low lying rivers
and grasslands are sweltering

in temperatures of nearly 30 degrees,

2,000 metres up Yellowstone peaks
have a recent dusting of fresh snow.

And the mountain meadows
are a riot of colour.

It is amazing, the contrast up here
to down in the valley.

Down in the valley,
summer has really taken grip.

The temperatures are quite high
and the grass is starting to go brown.

But up here, 800 metres higher,
it's a totally different story.

It's breezy, it's cool, and look
at all these magnificent wild flowers.

Susan Marsh is a naturalist,

and she pays very close attention
to these high-altitude wild flowers.

Where most people see pretty petals,

Susan sees a living record

of how this ecosystem is being affected
by this year's weather

and the changing climate.

We've looked a lot

at how animals can indicate
the state of how a year is progressing

as far as the weather is concerned.

Are the plants
just as valuable as indicators?

Yes, um, I think they are,

and the one advantage that they have,
in my opinion,

is that they don't run off.

-HUMBLE: [LAUGHING] Yes, very true!
-And they don't fly away.

So, I can tell by how tall they are,
first of all.

-Right.
-Uh, this one is fireweed.

-Okay.
-And it typically,

in a really lush year,
will grow head-high.

-Wow.
-Even at this elevation.

And these particular ones, you can see,
are only a couple feet tall.

-Yeah, yeah.
-And, to me, that's an indication

of heat and dryness.

The plant needs to set seed,
and it has a very short growing season,

so it's not gonna waste its energy
making a big, tall stalk

-or making great, big leaves.
-Right.

These leaves are small this year,
smaller than usual.

HUMBLE: Through these plants,

Susan can chart
this year's erratic weather.

But can plants
also indicate larger changes?

Everyone is talking about
the fact that the climate is changing.

Is that something
that is becoming evident in the plants?

MARSH: It's typically
on the mountaintops.

-So that's above the treeline?
-Above the trees,

where there's rocks, and wind, and cold.

HUMBLE: It's the coldest part
of Yellowstone,

above 3,000 metres,

where Susan is seeing
the effects of climate change hit hard.

This is the alpine zone,
a realm of high-altitude specialists.

But as temperatures keep getting warmer,

non-specialist plants are
able to survive higher up the mountains,

and they're invading this fragile zone.

Does it concern you that you are seeing

a march towards
a very different climate,

and therefore,
a very different ecosystem?

I think there'll be
some good and some bad

depending on what species you are,
as climate change continues.

But, yes, I don't want to lose
the wild flower parks that I love.

I don't want to lose the alpine zone.

[BUZZING]

I don't want to see those go,
but I don't think I can stop it.

HUMBLE: Climatologists
studying Greater Yellowstone

have charted temperatures increasing
by nearly a fifth of a degree

every decade.

This seemingly small change
is having far-reaching consequences.

Across Yellowstone,

scientists are seeing how animals
are being forced to adapt.

[GROWLING]

Even the most iconic species
like the grizzly bear,

are being affected.

To find out what's going on,

Patrick has gone
to the Gallatin Mountain range

in the north-west
of Greater Yellowstone.

ARYEE: I've come to meet
our bear expert, Casey Anderson,

to see how one group of grizzly bears
is coping

as the changing climate
threatens an important food source.

If you look up at this knob up here...

Yeah, take a look at the trees
just around the bottom of that.

-Those are white bark pine.
-ARYEE: Let's have a look.

ANDERSON: That entire forest
of white bark pine, ancient trees,

some of them are 300 years old,

they've all died
in the last couple of years.

They're gone.

ARYEE: What's caused it to die off?

Well, there's a pine beetle
that's always existed up there,

but we've had these cold winters

that have usually
just killed most of the beetles.

But now with climate change,
those winters are not as harsh,

we're not having that beetle-kill
that we're used to

in the middle of the winter,

so the beetles are really
starting to infest the forest.

ARYEE: Pine beetles
are no bigger that grains of rice,

but these small creatures
cause big problems.

Not only do their young
eat the trees' living tissue,

but they also introduce
a destructive fungus.

Eventually, this combination
kills the entire tree.

This is bad news for the animals

that rely on the food and shelter
this tree provides.

Towards the end of summer,
as other food sources dry up,

these pine nuts usually
provide vital protein for grizzlies.

One aerial survey

revealed around 80% of mature
whitebark trees in Greater Yellowstone

show signs of moderate
to severe beetle infestation.

To survive, the bears must adapt.

And Casey has witnessed
some intriguing behaviour.

Grizzlies are leaving the wilderness

to congregate
on this cattle ranch to feed.

ANDERSON: What they're eating
is this caraway root

that actually came in
with the livestock.

It's actually an introduced species
not native to the area,

and they're coming down
and taking advantage of it.

And all the bears in the area

are starting to migrate
towards this meadow

because there's not a lot of food
out there in the summer.

But right here,
this is like a bear buffet.

ARYEE: It's a race against time.

The bears must pile on enough fat

to see them through
five months of hibernation.

While the root is at its most abundant
in summer and autumn,

the grizzlies
gorge throughout the night,

eating up to 20,000 calories
in a single sitting.

As the day heats up,

the hot sun forces them
back into the shady forest to rest.

But Casey and our mobile camera team

have seen two bears
that are still out in the midday sun.

MAN: [OVER RADIO]
Hey, Casey, do you copy?

[BEARS GROWLING PLAYFULLY]

They're, like,
totally tumblin' around out there.

[LAUGHS] Well, little playful guys.

[BEARS GROWLING PLAYFULLY]

ARYEE: These two yearlings are orphans.

Unfortunately,
their mum died last autumn.

But against the odds,
they've turned up in this meadow.

I've joined Casey
to see how they're doing.

Well, they're right here.

There's two yearling grizzly cubs
right out here, digging around.

ARYEE: [WHISPERING]
Oh, yeah! Right there!

They're still young and inexperienced.

Cubs usually stay with their mums
for up to three and a half years,

but even with this protection,

almost a third
won't survive in Yellowstone.

It's a miracle that these two made it
through an entire winter on their own.

I mean, do you think
that having one another

is one of the reasons
why they've made it this far?

I think it's gotta be
one of the biggest reasons.

If they didn't have each other,

I don't think there's any chance
that one of them would've survived.

Yeah, they've got each other's back.

ARYEE: Whilst feeding
on this working ranch,

there are lots of unusual
sights and sounds.

[COWS MOOING]

[WHIPPING]

But without a mum to teach them,

it's hard for the cubs to know
what is and isn't dangerous.

ANDERSON: You find yourself
really worrying about them

because they don't have
that notorious mama grizzly

-looking out for 'em.
-Mmm.

Yeah, they're looking
a little bit nervous.

It's like they're looking at something

over in the distance.

ANDERSON: They obviously
sense something in that direction.

I think that these two
have probably been chased

probably once a day by something,

whether it's another grizzly,
a pack of wolves,

or even cattle.

ARYEE: Surprisingly, the dangers may not
come from the ranchers or their cattle.

Most have learnt to live
alongside their grizzly neighbours.

One of the biggest threats
comes in the form of other bears

close by in the shade of the forests.

A big, male grizzly, known as a boar,
could kill and eat the cubs.

But it looks like these two
have found a way to avoid this danger.

The big boars and other bears
are out at night

'cause when it's hot like this,
most bears will not come out and dig

'cause it just wears 'em out.

And as the sun comes up,
they go back to the forest,

while these little guys, they're kind of
on the opposite schedule.

The danger goes away, it's time to eat.

"Let's do it in the heat of the day
when there's nothing else out here.

"We don't have to worry about anything."

And that's what they're doing,
and it's working for 'em.

It's an amazing strategy.

ARYEE: The two cubs
are a fantastic indicator

of just how intelligent bears can be.

Even as climate change
kills off the whitebark pine,

the bears are adapting
to exploit new opportunities.

With over 700 grizzlies
in Greater Yellowstone,

the latest data
suggests their population,

for now at least, has remained stable.

HUMBLE: Yellowstone hasn't reached
its record temperature of 36 degrees,

but climate data
has revealed that July this year

was the seventh month in a row
with above-average temperatures.

The relentless heat and the early thaw

are a dangerous combination.

They may create perfect conditions

for wildfires.

In normal years, the snow melt
would come down off the mountains

and it would hang around
places like this,

soaking into all this dead wood,
but not this year.

What it did, was come rushing off
in a great torrent

into the rivers,
into the streams, into the lakes,

and it didn't have time
to soak into all this dead, dry wood.

So this is basically fuel for fires.

And having so much dead, dry wood around

means that there is a danger, this year,
of bigger and more intense fires.

[THUNDER RUMBLING]

A single spark
could set this landscape alight.

Every summer, an average of 26 wildfires
are started by lightning

across Yellowstone National Park.

Our crew are out following up
on reports of wildfire.

Flames can reach heights of 50 metres,

exceed 1,200 degrees Celsius,

and rip through the landscape
at up to 14 miles per hour.

By mid-August, the tinder-dry conditions
means five major fires have taken hold

and are raging across the region.

ARYEE: In the Beartooth Mountains

is wildlife cameraman Jeff Hogan.

Oh, no, this is nuts!

ARYEE: He's filming a wildfire
that's consuming a huge area of forest,

and it's headed straight towards
the family of great grey owls

he's been following since spring.

This fire is huge and it's raging,

and it's right in the backyard
of our great grey owl family.

This is really a threat.

[SCREECHING]

ARYEE: So far, the chicks
have done much better than expected.

There was only a 20% chance all three
would make it out of the nest.

[WHISPERING] Oh, he's gonna go,
he's gonna go! Jump, jump!

Oh, wow!

ARYEE: Jeff thought
their biggest challenges were over...

[FIRE CRACKLING]

...but now, he'll have to wait
until the fire's died down

to see if these young owls survive.

Oh, my goodness!

The aftermath of a fire
might seem devastating,

but it's actually
part of the forest's natural cycle.

It brings growth and new life.

All this ash is actually really fertile,

and as soon as it rains,

new green shoots
are going to start popping up,

and that's going to encourage grazers
like elk and deer

to come into this area,
and eventually, grizzly bears.

But not only that.

Some plants have actually evolved
to benefit from fires.

These here are lodgepole pine cones,

and they only open up once they reach
a specific temperature

that can only be produced by a fire.

And then these seeds
will eventually fall off

down into the ground
and be fertilised by the ash.

Fires are a natural part of life here.

But by the time they die down,

they will have burnt
nearly 100 square miles of land.

This year's fires

will have been the most destructive
inside Yellowstone National Park

since 1988.

Large scale fires used to sweep
through the park around every 300 years.

But scientists now believe
that the warming climate

could result in them happening
every three to five years

by the end of this century.

This could result
in the destruction of the forest

that's home to the fragile population
of great grey owls.

Jeff is searching the area
at the edge of the burn

for any sign of the owl family.

There's a lot of ground to cover,

so Jeff calls in expert animal tracker
Dan Hartman.

After four days searching,

Dan finally hears an adult great grey.

[OWL SCREECHING]

And close by, one of the young owls.

[SCREECHING]

After another few minutes
watching and listening,

he spots the other two siblings.

[SCREECHING]

[SCREECHING]

All of them have survived.

[OWL SCREECHING]

And they're even making
their first attempts at hunting.

The owl chicks have all
made it through their first summer,

but we still don't know the fate
of the beaver mum and her three kits.

I've joined Jeff
on a tributary of the Snake River

where he's seen signs
that the beavers are making a new home.

He thinks it's a safer location

as the water level
is higher than at their old pond.

[QUACKING]

HOGAN: Oh, look!

There's your beaver.
It's sitting there by the stack.

ARYEE: Oh, my... It's that beaver there!

That's the beaver right there.

ARYEE: This is just gold dust.

This looks like mum,

and in the few weeks since moving,
the family has been busy building.

HOGAN: That is a new lodge
being built right now.

They just make a big pile of sticks,

then they go into it
and start digging it out,

and they'll pile mud and stuff
up on top of it.

This is a lodge at its early stages.

HOGAN: This is rare.

Rarely do you see the very early stages
of a whole new beaver pond

with a lodge like this.

ARYEE: They're concentrating
on their dam,

strengthening it with rocks

and plugging any leaks
with weeds and mud

to create a deep, wide pond.

The water table here is rising

so that they can reach out
and get more of this food,

the trees that grow around here,
cottonwoods, alders, willows.

ARYEE: The beavers can now access
all this untapped food

without having to venture far
onto dry land where they're vulnerable.

HOGAN: [WHISPERING]
There's a beaver right there!

ARYEE: Finally, Jeff spots
what we've both been hoping to see.

-[WHISPERING] Running up there.
-Oh, yes.

There's a new one!

-There's a young one.
-Yes, yes, yes!

ARYEE: Whoa!

We've got our three young beavers
right here, the three kits.

They're getting big.

-They are.
-They're getting big, fast.

ARYEE: Mum's risky gamble
appears to have paid off.

This deep pond, with a new lodge,

and plenty of food,

is everything
the kits will need to thrive.

They're so inquisitive, aren't they?

And they're just...
They're just fabulous to watch.

The kits will stay with their parents
for the next two years.

In that time, they'll learn
the engineering skills needed

to build a dam and a lodge.

The secret to the beavers' success

is adapting the landscape
to suit their needs.

It's engineering on a scale
that has only been surpassed by humans.

HUMBLE: Every year, the challenges
in Yellowstone are getting greater

as climate change
results in more extreme weather.

Yellowstone's residents have developed
clever strategies to survive,

but the last animal I want to see

is quickly running out of options
as temperatures rise.

I've come up to 3,000 metres
and the fragile alpine zone.

Only one specialist mammal
is active up here all year round.

The pika.

[CAMERA SHUTTER CLICKING]

And Kaitlyn Hanley is the
hardy researcher who studies them.

I've got glimpses of pika.

Are they a member of the rabbit family?

They're called the "rock rabbits."

-[PIKA CALLING]
-Oh, there was one.

-That was a call?
-[LAUGHS] Yeah, that was a pika.

Come on, come on, Kaitlyn.
I want you to scout...

There he is. He's right there!

HUMBLE: Oh, my goodness! There he is!

Pikas are thought to evolved
from ancestors in Siberia,

one of the coldest places on Earth.

Their odd appearance
is all about keeping warm.

[PIKA CALLING]

A plump, round shape
minimises surface heat loss

and thick fur
covers their entire bodies,

even their toes!

For pikas,
summer is all about collecting food.

I imagine, that up here,

the season where there's any food at all
is pretty short.

Yes, and they don't hibernate
in the winter,

so they actually collect hay
through the entire summer

and they'll use that
as their food source during the winter.

HUMBLE: So that's what
they're doing now?

HANLEY: Yes, they're haying, yeah.

They'll get these huge hay piles
under their rocks

and they'll that in the winter and eat.

-HUMBLE: Really?
-Yeah, they're the only mammal

that doesn't hibernate up this high.

HUMBLE: And they can survive?
HANLEY: Yes, they survive.

I mean, the snow must come here,
what, in October?

Yes, it would be October
most of the time.

-Through to...
-March-May.

So they've got a matter of months
to collect enough hay

to get them through
the whole of the winter?

HANLEY: Yes.

They're busy little bees,
that's for sure.

HUMBLE: Pikas love a cool climate.

Just a few hours' exposure
to temperatures of 21 degrees

can prove fatal.

So they can only exist in Yellowstone
above 2,000 metres.

[CALLING]

Soon, even here,
they may have nowhere left to go.

Because these animals
are such high-alpine specialists,

they can't survive
at the lower elevations.

Does that make them
particularly vulnerable

to things like climatic changes?

Absolutely.
They are very sensitive to heat,

and so, as climate change
and the habitat changes for them,

they're gonna move up-slope.

They're already up-slope at this point!
You can't go any farther.

And so, for the pika, you know,
they don't have anywhere to move.

They're running into the sky.

HUMBLE: Scientists
have already seen pikas disappear

from one-third
of their former strongholds

in warmer states to the south.

But Yellowstone's high country
still provides sanctuary,

at least for now.

HANLEY: I have hope.

I... I don't think we should lose hope.

-[BOTH GIGGLING]
-'Cause they're too cute to go extinct.

[BOTH LAUGHING]

That's one very good reason
we should all be there to save the pika,

is that it's just too cute
to go extinct!

[CALLING]

ARYEE: The arrival of autumn
marks the end of the great thaw.

We've seen how
the dramatic seasonal changes

affected Yellowstone's wildlife.

The mild winter
meant the wolves struggled to hunt

strong, well-fed prey,

and many went hungry.

[HOWLING]

But in the summer,
they used their cunning to find food

and keep their pups alive.

The beavers survived the spring run-off,

and were able to build
an entirely new home

to raise their three kits.

[SCREECHING]

Our great grey owl runt
beat all the odds

and fledged with its two siblings,

giving this vulnerable population
a much-needed boost.

The grizzly bears' race to fatten up
started early

with the mild winter conditions.

The wet spring and early green-up
revealed a bounty of food.

But by summer, they had to use
all their resourcefulness to survive.

This has been a magical window
into the lives of wildlife

in a truly spectacular landscape.

HUMBLE: We've also seen
a bigger picture unfold

as scientists try to predict

what the future for Yellowstone
will look like as the climate shifts.

I think what we do know
is all of it's gonna change,

and it's changing pretty rapidly,

and we don't really know
how it's gonna change.

There'll be some good and some bad
depending on what species you are,

as climate change continues.

HUMBLE: There are still
many challenges ahead,

but if there is one thing
that all of Yellowstone's animals share,

it's their incredible ability
to adapt to extreme change,

and this will give them
the best possible chance to survive

whatever the future brings.