Original subtitles

At the southern tip of South America,

the Andes mountains rise almost vertically.

Their very height affects life throughout the continent.

The barren slopes look inhospitable.

But like all parts of South America, they're actually rich with wildlife.

A family of puma.

They live further south than any other kind of cat on Earth.

These cubs are only six months old -

entirely dependent on their mother for food.

She knows how to exploit this rugged landscape to her advantage.

And she has to do so,

if she is to catch the continent's most challenging prey.

Guanaco - a relative of the camel.

Two metres tall and over three times the weight of a puma.

The mother's only hope is to go for the throat and try to suffocate her prey.

Her cubs try to help...

...but they themselves don't yet have the skills or the weight

to bring down such large prey.

And the mother is now badly injured.

Her wounds are severe and will take weeks to heal properly.

But without food, her cubs won't survive for long.

The weather in the Andes is harsh and unpredictable.

Snow makes the camouflage on which she relies much less effective.

But she must have food.

The guanaco have left her normal hunting ground...

...and are now in the territory of a much larger male puma.

He's just made a kill, but he isn't about to share it with her.

To hunt here, she'll need to leave her cubs behind

in the safety of their home territory.

Almost invisible in the shadows, she's nearly within pouncing distance.

Another failure.

She's got her speed back.

Now she must hold on.

But she is in the male's territory, so her prize isn't safe...

...and her hungry cubs are over kilometre away.

In her weakened state, she will need all her reserves of energy

to drag it back onto her territory.

Only her determination to feed her young keeps her going.

Nearly there.

This one meal will barely last the whole family for more than a few days.

Then their mother - somehow - will have to summon the strength to hunt again.

Life for a hunter in this land is as hard as it gets.

The Andes themselves were built by forces deep in the Earth's crust.

In this part of the Pacific,

the ocean floor has been moving eastwards for millions of years.

Where the sediments meet the edge of the continent,

they're pushed together and forced upwards.

This pressure creates fractures up which molten rock rises

and is then spewed out as ash and lava from great volcanoes.

Nearly 200 of them stretch in a line along the length of the continent.

Some erupt with the force of an atomic bomb every ten seconds.

As the collision continues, the sea floor is dragged downwards,

creating a deep trench just offshore.

Rich, cold waters rise up from it.

And this upwelling creates an abundance of life.

Here, on the coast of Peru,

there are so many seabirds fishing in the offshore waters

that the cliffs are covered in droppings over a metre thick.

Humboldt penguins regard the soft guano

as a good material in which to dig their nest holes.

But it's a messy business.

It's the breeding season, and more hopeful nesters arrive,

spotless from swimming in the sea.

Time for the residents to get cleaned up and catch some fish

for themselves and their chicks.

To get to the sea, they cross the remains of an old nesting ground.

Only 100 metres to go.

But the beach is already crowded with sea lions.

They too have come ashore to raise their young.

And they don't like being disturbed.

To get through such a minefield needs a bold and courageous leader.

A brave start.

A dead end.

Now he's in trouble.

This is going to need a bit of crowd surfing.

But now all the sea lions are roused.

Getting through them will be tricky.

A cleansing bathe in the ocean...

...well worth the effort.

The animals living along the Pacific coast

are cut off from the rest of South America by the Andes.

They form a gigantic barrier, stretching over 6,000km

from Patagonia in the south to Venezuela in the north.

This is the world's longest mountain range.

Some peaks are almost 7km high.

They are so tall they catch clouds...

...and so create an environment unlike any other on the continent.

The cloud forest.

Every high valley here has its own unique plants and animals.

One of them is the aptly named Pinocchio lizard.

It was first recorded here 50 years ago and then lost.

It's only recently been rediscovered.

Up here lives a creature so rare that it's seldom seen,

even by those scientists who have come here to study it.

The Andean bear.

Only a few thousand remain.

They eat mostly leaves and fruit,

often clambering up to the very top of the canopy to do so.

He's looking for a type of miniature avocado...

...30 metres up.

The only fruit remaining here is out on the thinnest branches -

too thin to support the weight of a bear.

A more experienced bear has turned up and wants a go.

Time for young ones to watch and learn how to do it.

The trick is to bite the branch just enough...

...to make it swing down and bring the fruit within reach.

Whoops!

Now there's a race to be first on the ground to claim it.

The moisture needed to create a cloud forest

only occurs above a certain altitude...

...so each peak may now have its own species.

In Venezuela, there are similar small worlds,

created not by rain, but by rock.

A great layer of sandstone once covered this entire area,

but rivers cut through it.

As the valleys widened, the tablelands became first huge plateaus,

then isolated flat-topped mountains...

...and, eventually, towers and spires.

On the tops of the bigger ones, animals and plants have now become so different

that they can be counted as new species.

There is no higher waterfall in the world...

...than this one.

Angel Falls - almost a kilometre from top to bottom.

The vertical cliffs surrounding many of these mountains

have kept them largely free from human exploitation.

No such barriers have protected the lowlands...

...but a few patches of forest still remain.

One in Colombia is the home of one of the world's rarest monkeys.

Cotton-topped tamarins.

They're critically endangered.

Only a few hundred families remain.

They live largely on fruit

and are particularly fond of tree sap.

This is packed with sugars, so it also attracts insects.

But tamarins like them too -

a little bit of protein to add to their diet.

There used to be over 50,000 species of insect to choose from...

...but as the forest has shrunk around them,

it's becoming more difficult to find the right ones.

South America is changing.

Over 95% of Colombia's lowland forest has now been cleared.

Farming has taken the biggest share.

This patch of forest is now isolated.

The few tamarin families here

are now cut off from the rest of their species...

...and beyond their boundary lies an alien world.

Today, more than 2,000 species of animal in South America are under threat.

All across the continent,

forest is being steadily cut down and replaced by farms.

Images from space reveal the scale of the destruction.

Throughout South America as a whole,

an area of forest the size of a football pitch is being lost every five seconds.

Of all the forests at risk,

perhaps the most precious lies in the very heart of the continent.

The Amazon rainforest -

the largest on Earth.

Over two million species of plants and animals now live here -

more than is found on any other of the Earth's seven continents.

Food is so abundant that some male birds, instead of helping with nest duties,

try to mate with as many females as possible.

This is a male manakin showing off to a female.

He does so by dancing...

...and he has a team of subordinate males to help him.

By supporting him now, they may themselves eventually become leaders

and get a chance to mate.

The team is assembled and the performance begins.

She takes a closer look.

The top male signals the end with a final flourish.

What's the verdict?

Not good enough.

Unbelievable!

So it's back to practising.

Each animal species in this crowded environment has to have its own way

of creating a niche for itself.

This is a poison dart frog.

Males raise their young in a very special way.

A father will place each one of his tadpoles in its own tiny pool of water.

This is one.

Nice and safe.

He might have up to five other tadpoles.

But he needs to remember where he put each one of them.

This one isn't doing so well.

His tiny puddle has all but dried out.

The tadpole will die unless its father can find a better place for it.

If dads are good for one thing, it's piggyback rides.

Fathers are no bigger than a human thumbnail,

but this enables them to get to places that others can't.

This could be perfect.

The only problem is that there's no food here.

Fathers need help.

Somewhere in this forest...

...is...

...mum.

A female could do something a male cannot.

But first, dad must lead his partner to their hungry tadpole...

...and mother deals with the problem.

She lays a single unfertilised egg.

And her tadpole gets a much-needed meal.

For the next six weeks, parents continue their rounds -

an extraordinary test of teamwork and memory.

Warmed by the tropical sun, the Amazon's trees release so much moisture

from the surface of their leaves that they create their own clouds.

And these, over the course of a year, release up to six metres of rain.

The water flows through the saturated forest along a thousand streams.

They eventually unite to form the largest river of them all.

The Amazon carries more water

than the world's next seven biggest rivers combined.

Some sections of its banks are particularly sought-after.

Scarlet macaws travel over 100 kilometres to visit them.

Macaw couples bond for life and may stick together for over 40 years.

Pairs return to favourite trees, ones they've known for decades.

Parents provide their chicks with fruits and seeds,

but they're far from the ocean and their diet lacks salt.

Without it, the chicks' brains and bones will not develop properly.

So someone has to go and fetch it.

Many other creatures are looking for the same thing...

...a clay lick.

The earth here may be 40 times richer in valuable minerals

than anywhere else in the surrounding forest.

Over a dozen species of parrot jostle for space.

There's a strict order...

...in who feeds first.

Everyone is in a rush to fill up and get airborne.

Parents have to carry over 5kg of clay to the nest

before their chicks are ready to leave.

Once fledged, these young will follow their parents for up to a year,

learning where to find the salts.

Many of the great riches of South America lie far beyond the Amazon basin.

Over 1,000 miles to the south of the Amazon,

there's one creek unlike any other on the continent.

Here at Bonito, freshwater springs bubble up from deep underground.

Filtered through limestone, they create crystal-clear pools...

...and in them live some remarkable fish.

Piraputanga.

The water is so clear that they're able to see what is going on above its surface.

Brown capuchins are up there, looking for a meal.

The piraputanga watch them attentively.

Wherever the monkeys go along the banks, the fish follow.

The monkeys are on their daily search for ripe fruit,

and the fish cannot by themselves know where that might be.

But here it is.

And fortunately, the monkeys aren't the neatest of feeders.

Every scrap is fought over.

One monkey has the job of keeping an eye out for danger.

Anacondas are the largest of all snakes.

They grow to over 200kg.

And they usually stalk their prey from the water...

...but it's not fish that they're after.

If the monkeys stray too close to the water, they will be in danger.

The scout gives a warning call.

That might have to be the end of the monkey's meal for today.

But now the piraputanga know where the fruit is.

And there's still plenty left on the tree.

In the monkeys' absence, they go for it themselves.

Success or failure is just a matter of millimetres.

With a split-second adjustment, the fish bends in midair

and collects the prize.

The piraputanga's extraordinary feeding technique

relies on these waters remaining clear.

But today, the future of South America's rivers has become uncertain.

As the human population has grown, people have become more and more reliant

on its rivers for one of the essentials of modern life.

Power.

Two-thirds of South America's energy now comes from hydroelectricity.

No other region on Earth is so dependent upon it.

But the way these dams are managed can cause problems farther downriver.

These are the Iguazu Falls.

If the dams upriver suddenly release their excess, Iguazu can double in size.

And that can cause major problems for animals that live here.

These are great dusky swifts.

They fly alarmingly close to the thundering torrent...

...and then vanish.

Miraculously, they're able to fly right through the curtain of water.

And they do so because they've built their nests behind the thundering curtain.

Their enemies - falcons, like this caracara - can't follow them.

So the swift chicks are safe.

But now humans have created new problems for the swifts.

Just as some of the chicks are starting to fly,

the spill over the dams is released in full force.

As the torrent grows, parents give up on the last perches.

Now the chicks are alone.

But they don't yet have their parents' waterproof feathers.

Every year, the sudden surges of water sweep some to their death.

The chicks have never seen the world beyond the falling waters.

Unless they can find a way through, they will not survive.

Amazingly, driven by blind instinct,

chicks do manage to power their way through.

These remarkable birds have colonised a niche in which few can survive.

Yet their future, and that of all wildlife in South America,

will depend on us striking a balance between the needs of humans and animals,

on the richest and most diverse continent on Earth.

Next time...

...a continent marooned

during the time of the dinosaurs,

where the castaways...

...are like nothing else on Earth.

Australia.