Original subtitles

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 50 miles 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 5 kg 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 200 kg.

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.

To film one of South America 3 most elusive predators,

the Seven Worlds team would travel to the far south of the continent.

Their aim was to capture footage of wild pumas hunting.

But what the team encountered was the struggle of a mother

desperate to feed her family.

Chile's Torres del Paine covers nearly 1,000 square miles.

Cameraman John Shier has been coming here for eight years,

but even he has never witnessed a successful puma hunt.

With so much ground to cover,

the crew use the latest technology to scout from the air.

Bertie is setting up the drone cos it helps find the cats

and get a unique perspective

on exactly where they are in this habitat.

But expert tracker Roberto Donoso- has 15 years' experience here

and he relies on help from a surprising local.

No-one can spot a puma as well as a guanaco.

John is first to pick up the clues.

- Hey, cat... - Cat, yeah.

Cat. We've got a cat, OK.

You can see guanaco on the other side, alarm calling.

That cat is just sat on the ridge,

and the full moon has just risen right behind it.

It's almost cheesy.

Our very first puma.

Once John starts to get his eye in,

he realises-he's being watched by more than one cat.

It's crazy. So we're sitting here, we've got this young male

just over the ridge, so we've got that cat.

While you're sitting here,

you hear other guanaco alarming other spots

and you realise that there's just cats roaming all round the landscape.

Over the coming days, John sees more puma than ever before.

The situation is like nothing the crew expected.

For a long time, we used to say

that trying to spot puma was so unusual and so rare,

but the real, remarkable thing is actually we're seeing cats every day.

And to think that there's this many puma around is just... It's incredible.

After decades of persecution by humans,

puma are now protected in southern Chile and making a comeback.

But to stand any chance of seeing them hunt,

the crew would need to find just the right cat.

Three weeks in, john has spotted something promising.

He alerts the crew.

It was just up here to my right', about 100 yards from me.

- So he's to the right. - But closer to john.

Ah, got him. Yeah, yeah, yeah.

Wow, that's four, all right.

Looks like a pride of lions.

A mother with three cubs, and Roberto knows exactly who she ls.

Her name is Sarmiento-.

Her struggle to feed her family is now the crew's main focus.

The challenge is to keep up.

A mother on the search for food will roam vast distances.

Seven miles they've walked. Haven't stopped walking.

For the crew, this means dragging heavy equipment over difficult terrain.

So we've been following the cat so much

that there's now a hole in the bottom of my shoe.

Unpredictable weather makes it even harder.

Five weeks in and john finally thinks Sarmiento might have some luck.

So it's more of a hope,

but I think that she's going to get one of these guanaco today.

There's been a big herd that's streaming into this valley,

and for the last two hours, she's just been watching them, like laser focus.

Fingers crossed, today's the day.

She fought so hard, the guanaco fought really hard.

In the end, she didn't get it, but it's amazing

how she has to fight to get a meal to survive.

Trying to take down an animal as large as a guanaco

has left Sarmiento badly injured.

OVER RADIO". There's a lone guanaco, just up to the right.

Every failed attempt, she gets weaker...

Yeah, there you go. It was close, but, yeah, she got thrown off pretty good.

...but a hungry mother doesn't give up easily.

There's a group of guanacos-down here,

so we're trying to get in a good position to launch the drone.

- Can you see it? - Yeah, got it.

She's coming back.

The crew will only have seconds to get into position.

50, 50 metres. 50.

OK. 20, 20 metres. It's going.

20 metres.

It's going, it's going! It's running, it's running!

Witnessing this life-and-death battle is difficult.

But at last, John sees Sarmiento provide for her cubs.

I feel greatly relieved. It's been 30 days, 100 miles of walking with her,

and we've finally got her doing it.

During the chase, I was thinking, "This time, please, please get it down."

There's been three chases where it got away.

Her cubs have got food now. She had to fight for it.

Conservation efforts here have given these secretive cats a rare safe haven,

enabling the team to capture a filming first...

...and tell the remarkable story of a fearless mother

at the far edge of South America.

Next time...

...a continent marooned

during the time of the dinosaurs,

where the castaways...

...are like nothing else on Earth.

Australia.