Original subtitles

David Attenborough: The equator.

It runs across the scorched plains

of east Africa.

This is as far from the Poles as you can get.

But ice and snow are here too -

up in the mountains.

Every continent on earth has such high snowfields.

And each has its own community of animals

that have adapted in their own way

to the crushing conditions that come with the cold.

Dawn in east Africa,

on the high slopes of mount Kenya...

4,000 metres up.

The temperature is just beginning

to creep above freezing.

It's hardly the place where you would expect to find

a cold-blooded reptile.

But there is one that lives up here -

the high-casqued chameleon.

This female has survived

the night's freezing temperatures

by allowing both her metabolism

and her heart rate to drop significantly.

Now, in the morning, she needs to eat.

But it's so cold, she can't move her legs.

Her spring-loaded tongue, however, still works.

As the sun rises higher in the sky,

frozen land begins to thaw...

And the giant iobelias

spread their leaves to soak up the sunshine.

With her body temperature

still only five degrees celsius,

the chameleon becomes more mobile...

And climbs up to bask in the sun.

Her skin darkens...

Enabling her to absorb the sun's heat more quickly.

She is pregnant,

and soon her temperature reaches 20 degrees celsius,

which gives her

the energy she needs to give birth.

Most chameleon species lay eggs,

but here it's too cold

for an egg to develop in the open...

So she produces live young.

It takes just an hour

for her to give birth to six baby chameleons.

One of the advantages of life on the frozen peaks

is that there are fewer predators here...

And less competition for food.

But there's a reason why comparatively few reptiles

live in the high mountains.

As the sun sets,

the temperature falls to below zero

in a matter of minutes.

The babies must act fast.

To escape the nightly freeze,

they need the cover of thick vegetation.

A young chameleon caught out in the cold

will quickly lose its ability to move

and may we” die.

Most, however, react instinctively

and find shelter as quickly as they can.

Peaks on the equator, such as mount Kenya,

are frost bound for only a few hours each night.

But north of the equator,

in the 750-mile-long European alps,

the cold endures for months.

The high mountains are continuously frozen

for half the year.

A testing time

for the alps' greatest aerial predator.

The golden eagle.

In winter,

there is just enough prey up here, dead or alive,

to sustain them.

But when spring arrives, the mountains are transformed.

For a male and his lifelong partner...

The need to find food is urgent.

They have a three-week-old chick.

It needs to be fed several times a day.

To do that, both parents have to hunt.

Yet, even in spring,

few animals live up here in the high mountains,

and finding prey is not easy.

But chamois, a kind of mountain goat,

are here, and they are giving birth.

One of their kids can weigh as much as an eagle.

When eagles hunt as a pair,

they co-ordinate their approach.

One stoops...

Reaching a speed of over 150mph.

Its attack scatters the herd.

And that makes it easier

for the other to select a target.

A successful catch.

It could still be alive...

So the eagle carries it away, high over the gorge...

And then...

Deliberately drops it.

The impact will kill it instantly.

A chick can eat up to a third

of its own body weight in a day.

Parents can't afford to rest for long.

Taking advantage of the long summer days,

eagles hunt ceaselessly.

Day in...

Day out.

After eight weeks, a chick is almost fully grown.

And then,

as summer comes to an end,

the pressure on parents to feed their chicks...

Disappears.

Their young have flown the nest.

And just in time.

The worsening weather signals

that the leaner times of winter are on their way.

Finding prey has now got much harder.

The young chamois have also grown up.

A juvenile now weighs

almost five times as much as an eagle.

Animals of this size are no longer easy prey

for the birds.

They barely flinch under attack.

But it's dangerous for a chamois to stray

close to a cliff edge.

The eagles seize their chance.

Got it.

The eagle drags the chamois towards the edge.

It's an extremely risky move.

If the eagle breaks a wing,

it will be fatal.

A kill this size will feed a pair for days.

This is when they must build up the fat reserves

that they will need to sustain themseres

through the lean months that lie ahead.

Winters in the alps are daunting.

But in other mountain ranges, the challenges are even harder.

In the far east,

warm, wet winds blow in across the sea of Japan.

As they meet the 3,000-metre-high

Japanese alps,

they're forced upwards.

As the moist air rises,

it freezes...

And the water droplets they carry turn into snow.

No two snow crystals are exactly the same.

In the mountains of Japan,

13 metres of snow can fall in just a few months.

It's the snowiest place on earth.

To survive here,

an animal needs all the help it can get.

In winter, Japanese macaques

can live at altitudes of up to 1,500 metres...

Higher than almost any other primate.

But here, the warm volcanic pools

are always ready and waiting.

A nice hot bath lowers stress hormones for them,

just as it does for us.

Admission to this spa, however, is tightly controlled.

The high-ranking females dictate who is allowed in...

And who will be left out in the cold.

This three-year-old male

has recently been expelled from his troop.

He's hungry.

Macaques are largely vegetarian.

In the winter, when food of any kind is scarce,

they will tackle anything remotely edible.

However, a lone young male is unlikely to survive much longer

unless he can find a way of keeping warm.

And to do so, he may have to travel through

up to 50 miles of empty forest.

Bare hands and feet

can become painfully cold.

Rubbing them helps restore the circulation.

Frostbite could be fatal.

Young male macaques are most likely to die

in their first winter than at any other time.

Butjust like him,

here is another young male outcast.

Offering to groom is a standard way of establishing

a friendly relationship among macaques.

And the stranger's warm embrace is very welcome.

By huddling together,

they shield each other from the snow,

and both their temperatures rise... just a little.

This could be enough to save the lives

of both of them.

Snow on lower mountain slopes can be a major challenge

for any of the animals that live there.

On the high peaks, however,

really heavy snowfalls can be lethal.

The rockies in North America.

They rise to heights of over 4,400 metres.

In the winter, the winds blowing across the high summits

can create snowy overhangs - cornices -

up to ten metres thick

and weighing many tonnes.

In the spring, as the temperatures rise,

the cornices may become unstable...

And that can be catastrophic.

Avalanche.

As it tumbles downwards,

it accelerates to speeds of 100mph or more.

Only a racer drone camera can follow its course.

In just two minutes,

up to a million tonnes of snow hurtle down the mountainside.

Avalanches can be hugely destructive,

and climate change is making them

more and more unpredictable.

In the south pacific,

on the islands of New Zealand,

one highly intelligent creature

has learned how to take advantage

of the volatile nature of mountains.

The kea...

A species of parrot.

It's the only one of its family

that can live above the snowline,

and the only one that actively looks for meat.

The carcass of a mountain goat.

This adult male kea has a razor-sharp beak...

Which is well suited for butchery.

Flesh rich in calories

will help him through the winter.

But he doesn't have it for himself for long.

A gang ofjuvenile keas.

These younger keas

shadow the older, more experienced adults...

To learn the tricks of mountain survival...

And where to find food.

But while waiting their turn...

There's time to play.

There's a benefit to this apparently carefree behaviour.

It helps establish long-lasting relationships

between the youngsters...

And even defuses tension...

So that when one kea finds a rare but substantial meal...

It often willingly shares it.

And that is very important behaviour,

particularly in winter,

when food is so scarce.

In larger mountain chains,

the quest for food can become even more demanding.

The andes in South America.

The longest range on earth.

It stretches for over 4,500 miles

down towards the antarctic.

At its southernmost end,

the sun remains so low in the sky

that it brings little warmth,

and temperatures regularly drop below freezing.

In winter, the land is shrouded in darkness

for almost 15 hours a day.

Here, a predator has to hunt

when it's so dark that only a thermal camera

can make its activities visible to our eyes.

The puma.

This one-year-old female faces a daunting prospect.

She has just left her mother and become independent

at the most demanding time of the year...

When prey is at its most scarce.

The only substantial targets are a kind of llama.

Guanaco.

An adult stands one-and-a-half metres tall

and is twice the puma's weight.

This female, however, has one advantage -

excellent night vision.

If the youngster can get within five metres of a guanaco,

she has a chance of success.

But the guanaco do have a very acute sense of smell...

And excellent hearing.

After six hours of patient stalking from downwind...

The puma is finally within striking distance.

A wasted opportunity.

Three failed attempts in one night

have drained her reserves.

Her inexperience is leaving her close to starvation.

Another faint scent.

But it's leading this youngster

into the territory of another puma.

Her neighbour, a female,

is older and more experienced than she is...

And has already made a successful kill.

The younger female must approach with caution.

Adult pumas are solitary by nature...

And don't normally welcome rivals.

She falls back in a gesture of submission.

But if she doesn't eat within the next few days,

she's unlikely to survive.

The larger female is now no longer actively feeding...

So she makes another approach.

At last, the owner ignores her.

Pumas are the only solitary big cat

known to share a meal with a neighbour.

Maybe the young puma, with the help of its neighbour,

will after all survive her first winter.

And maybe the older cat one day

will be in need of a favour returned.

The lower slopes of the andes are harsh.

But climb higher,

and the mountains become othennorldly.

Their altitude prevents rain clouds

from blowing in from the east...

Whilst another, lower range nearer the west coast,

prevents rain coming in from the pacific ocean.

This creates, between them,

one of the driest high-altitude deserts on earth...

The atacama.

There is, nonetheless, a lake here -

a volcanic one that is filled with extremely salty water

from underground.

And this attracts flamingos.

They come here each summer.

And here they nest and raise their young,

taking advantage of the lake's plentiful algae.

But with the arrival of winter,

temperatures at night drop to below freezing...

Conditions that even these Hardy birds

cannot endure for long.

The adults start to leave and head for warmer temperatures

lower down the mountain.

But they leave behind

their four-month-old chicks,

which are old enough to feed themseres

but not yet strong enough to fly.

With each passing night,

temperatures continue to fall.

And then, one morning,

after a particularly cold night,

the chicks find themselves surrounded by ice.

Huddling together

allows some to preserve

precious body heat.

But those on the outside

are left even more exposed.

And some have already succumbed to the freezing conditions.

The salty ice is now so cold

that it congeals on the chicks' feathers.

Weighed down, their chances of flying are even more remote.

Now 40mph winds whip across the lake,

driving down temperatures even further.

Yet this very wind that could kill them

might just be their saviour.

The youngsters turn to face it.

If they can catch it just right,

it could give them the lift they need

to take their very first flight.

For those encumbered with heavy loads of ice...

The struggle is almost too much.

Freedom at last.

Many animals that live amongst the frozen peaks

have, over thousands of years, become adapted

to meet the challenges of a high-altitude existence.

But now their world is changing

because of global warming.

Ice that has remained frozen deep within mountain glaciers

is starting to melt...

Accelerating their movement.

Over the three years that it took to film this series,

the quelccaya icecap,

5,500 metres up in the Peruvian andes,

has receded by a staggering 60 metres.

In Europe, some alpine glaciers

are now shrinking by 100 metres a year.

One of them,

the sankt annafirn glacier in Switzerland

has almost completely disappeared.

Most of the others are expected to have followed it

by the turn of the century.

The warming of the frozen slopes

could threaten the life of perhaps

the most famous mountain resident of all.

Hidden within the bamboo forests of western China...

Is a hot and bothered male giant panda.

He has spent the winter

sheltering lower down the valley.

Now it's early summer,

and his thick coat that protected him

throughout the winter has become very uncomfortable.

He needs to reach the cold of the higher slopes.

But before he can start the ascent,

he needs a good meal to give him the necessary energy.

Giant pandas eat almost nothing except bamboo.

But bamboo is so low in calories

that he needs to spend ten hours a day eating.

With breakfast over...

He begins his climb to higher ground.

But in no time at all...

He's hungry again.

This is going to be a long journey.

And it may be an even longer one in the near future.

As climate change raises the temperature in these mountains,

giant pandas may we” need to climb higher and higher

to find cooler conditions.

But the cold-loving bamboo they most favour

cannot move so easily...

And may disappear from the warmer lower slopes altogether.

So far, these snow-covered peaks

continue to provide this male with enough space

to feed and find a mate...

So he scent-marks his territory...

Panda-style -

with a handstand.

It may well be that in the next few decades

the mountains of the world will warm.

Should that happen,

many species will inevitably disappear.

But we should never forget the versatility and endurance

of the animals that have succeeded in colonising...

These icy islands in the sky.

In the frozen peaks,

the team's greatest challenge

was to film a successful puma hunt at night

for the first time.

The crew travelled to patagonia

in the depths of winter to torres del paine,

home to over 200 pumas,

the highest density on earth.

Still to find them in this remote wilderness,

greater than the size of London,

they joined the local puma expert Diego araya,

who has over 20 years' experience

of tracking these big cats.

This is something completely new for us,

because we've never been actually in pitch black

following cats,

and being able to keep up with them on foot

I think is going to be an incredible task.

This far south, at the tip of South America,

winter only gives them nine hours of daylight

to find the pumas before night descends.

But it's not long until they are treated to

a surprise encounter.

Definitely, we are not part of the menu, huh?

Getting this close to a wild puma

is a rare privilege for camerawoman Helen hobin.

It's very surreal, actually,

being in real life and seeing one.

By day, these well-studied pumas are approachable.

But as dusk descends,

they pick up the pace as they switch to hunting mode.

We're just going into the pitch black pretty soon

and we have to rely on

thermal the rest of the night.

Armed with a state-of-the-art thermal-imaging camera

and spotting scopes,

they attempt to follow the puma in the pitch black.

The cats are moving so fast at the moment,

they can cover miles,

and it's quite hard to keep up, with all of our equipment,

and not really being able to see where you're going.

A few hours later,

and the pumas have given them the runaround.

You can see a heat signal on the hill.

Radio: Do you see them?

Yeah, I think we've got eyes on them.

Where is she?

I'm on the guanaco.

I feel like we had a puma that we all lost somehow.

But I'm pretty sure we've been standing here

staring at a bush with a hare in it.

As weeks pass, the crew experience the full force

of the patagonian winter -

100mph gusts of wind and blizzard conditions.

It's just one thing after another at the moment.

Finally, with a break in the weather,

their persistence pays off.

The situation is that we found a puma

and there's a group of guanacos.

This could be the break the team need

and offer them the opportunity to film another night hunt.

To optimise their chances,

Helen launches her secret weapon.

A thermal camera drone

that will act as their eyes in the sky...

Guiding the ground crew to within 20 metres

of the hunting big cat.

It's pitch black. There's a puma.

It's a little bit unnerving.

She's off. She's moving.

She was so close to that one to start.

She just didn't quite reach it. It was like that close.

Super frustrating, because now we're getting to walk

many more miles.

Over the coming nights,

the team continues to follow the young puma

as she attempts hunt after hunt.

Helen: It's just a roller-coaster all the time.

Something looks like it's gonna happen,

your adrenaline gets pumping, trying to get the shot,

and then just...

Lost count how many failed attempts. Too many.

With only a week left to film a successful night hunt,

the pressure is mounting on the crew.

We're still struggling to get the key behaviour

we're looking for.

But then the young female does something truly remarkable.

She didn't manage to make a kill,

but she came across another cat that has,

and she's been slowly over the course

of the last... I don't know how long,

I think it's been hours,

creeping towards her really submissively,

trying to ask for a bit of food.

It's quite the experience when you're standing

in their proximity and you can't see 'em

but you can just hear the crunching of the bones.

It's just so amazing to see. You can hear it

echoing all around as well when they growl.

Ooh!

Until recently, pumas were considered solitary animals,

but the crew's success with the thermal camera

reveals two unrelated cats

sharing the same kill at night.

You realise how far they are from solitary individuals.

This is like a fellowship of creatures

living in the same territory.

New technology has shed light on

the surprising survival strategy of the andean puma.

Just one of the many mysterious animals

that inhabit our planet's remote frozen peaks.