Original subtitles

Almost 200 years ago, whilst walking these very paths in the

English countryside and observing the banks and meadows near

his home, Charles Darwin developed his groundbreaking ideas

about evolution, casting a new light on the natural world

and opening our eyes to its true wonder. Since then, we've

explored almost every part of the planet and seen nature in

its astounding variety, but there's still much to discover.

In this new series of Planet Earth, we travel to the most astonishing wild places,

see mysterious creatures,

witness spectacular wonders,

and reveal breathtaking animal dramas.

The natural world continues to surprise us, but

since Darwin's time, it has changed beyond

recognition, transformed by a powerful force, us.

We will see how animals are adapting in extraordinary

ways to survive the new challenges they face.

At this crucial time in our history, we must now look

at the world through a new lens. This is Planet Earth 3.

Tasmania, ship's stern's bluff, where two worlds collide.

These waves have crossed more than a thousand miles of open ocean,

building in strength.

It's here that they meet their explosive end.

Coasts are dangerous and dynamic frontiers. To

succeed here, life must adapt to constant change.

South Africa's Roberg Peninsula.

Thousands of Cape fur seals gather here to breed.

This pup was born into a crowded world.

But now, at nearly a year old, he can escape to the water.

He just has to get there.

There is no question as to where this pup belongs.

In the water, he's fast and agile.

And he needs to be.

The rolling surf conceals life-threatening dangers.

It's here that they meet their explosive end. A great white shark.

This young pup has had a very lucky escape.

Here on Africa's southern coast, seals risk their lives every time they set out to eat.

Powerful ocean currents attract huge shoals of fish.

But in recent years, this stretch has attracted

increased numbers of great whites, too.

The great whites are shrewd hunters and use whatever cover is available.

The shark won't need to eat for another few days.

But he's not alone.

These usually solitary hunters are gathering in unprecedented numbers.

A dozen at a time.

The seals are nimble, but

great whites are patient.

And have explosive acceleration.

Hitting top speed with just five swipes of their tails.

Cornered, the seals keep close to the jagged cliffs.

They're trapped.

They're trapped.

But as the great whites move in for the kill, the seals do something astonishing.

Together, they turn on their enemy.

As more join, the mob grows. In both number and confidence.

The tables are turning.

My sheer force of numbers. These fur seals

drive the world's most notorious predator back

out to sea.

Here, animals are adapting to new challenges in a rapidly changing world.

In the Arctic, monumental change is a regular event.

Some visitors are arriving en masse, attracted by the

biggest seasonal transformation on any coast on Earth.

Over 300 billion tons of ice are melting,

releasing nutrient rich water.

Extraordinary newcomers appear from the depths.

A sea angel.

No bigger than your little finger.

It's eaten little for months. Its empty stomach glow as orange.

And there are other hungry arrivals.

A sea butterfly.

A snail with wings.

Both angel and butterfly are blind. But each monitors

minute changes in the water as they search for a meal.

This angel has a devilish side.

Its mouthparts invert to form a deadly trap of tentacles.

From which there is little chance of escape.

With a stomach full of prey, this angel has lost its glow, but not its appetite.

It feasts while it can.

Both predator and prey will soon return to the depths,

before the ice transforms this coast once again.

Namibia, where desert lions roam across vast territories.

These desert cats are on a never ending search for food.

And that has brought these young sisters here.

Africa's infamous skeleton coast.

Following years of persecution, Namibia's lions are now

protected. And their range is expanding again. These are the

first to be seen on these shores for 40 years.

By day, there is little for them here.

But at night, it's a different story.

Seabirds come here to roost in leather houses.

These hungry sisters have never seen an opportunity like this.

But no cats, certainly no desert cats, enjoy getting their paws wet.

These roosting cormorants are sitting ducks for hunters with good night vision.

Birds are not a big cat's usual prey, let alone

seabirds. And these sisters need to get their iron.

They need to get their iron.

Catching flying prey in the dark is not easy,

but these lions have acquired the knack.

Coasts can not only provide food,

they

can also be a sanctuary.

This female southern right whale is nearing the

end of a 5 ,000 mile journey across open ocean.

She's kept a steady course to a special place she has known all her life.

Peninsula Valdes, Argentina.

In these calm shallow waters, her behavior starts

to change. She rolls and shifts her great body.

Perhaps she's trying to get comfortable.

Other females are close by.

Some have been coming here for five decades, seeking

the shelter of this bay at a key time in their lives.

This whale is here to give birth.

A new life begins.

The calf is totally dependent on its mother.

She's producing as much as 200 liters of milk

a day. The strength she loses, the calf gains.

And it becomes more and more independent and playful.

In this nursery bay, there are plenty of playmates.

But a mother never lets her calf stray too far.

And will always offer a welcome embrace.

The family keeps in constant contact with whispered calls.

New research has revealed that in shallow coastal waters,

their calls not only fade quickly, but are also

concealed by the sound of waves breaking on the shore.

So they won't attract the attention of predators.

Not so long ago, these whales faced a graver threat.

They were hunted to near extinction.

But 40 years ago, commercial whaling was banned.

Today, their population is 12,000 strong. And this bay

now attracts one of the largest gatherings of these whales

anywhere on Earth.

There are over a million miles of coastline around the

world. Together, they constitute the most varied habitat on

the planet.

Here on Canada's west coast, some of the most powerful of

all ocean currents deliver a constant supply of nutrients to

the shores of countless islands.

And those that live here take full advantage.

This is the aptly named wandering garter snake.

He may seem out of place, but he's here to eat.

The water here is more than 10 degrees colder than the air.

But that doesn't deter this intrepid hunter from taking the plunge.

Under the water, there is an abundance of food, if he can catch it.

Snakes are cold blooded. So he can't stay in these chilly waters for long.

Back in the sunshine, he warms his head, perhaps sharpening his senses.

And then, with a gulp of air, he continues his hunt.

It's thought that garter snakes can use their forked tongue

underwater as they do in air, smelling in stereo, detecting

prey wherever it hides.

He's got something. A small fish.

Now he has to land it.

Success.

For those animals able to cross the divide between

land and sea, there are surprising rewards.

Raja Ampat in Indonesia.

Here, there's a greater variety of animals than on any other coast on Earth.

The corals are protected by mangroves, salt tolerant

trees that prop themselves on curving aerial roots.

These fish have learned how to catch prey from high in the trees.

Archer fish use jets of water like arrows.

This pinpoint accuracy requires some complex calculations.

A hunter first estimates the range of its target.

Then loads with a precise amount of water. Aiming, they

allow for the refraction and distortion created by the

water's moving surface.

And then release an

arrow of water. They can hit prey up to two meters above them.

But they're not born with this skill. They have

to learn it. And they do that by studying others.

This youngster is watching a master at work.

It's time for the apprentice to have a go.

First, he must select a target. This seems rather ambitious.

Missed. Others watch to learn from his mistakes.

Or to steal his prize.

Enough is enough. There is one way to beat the thieves.

The Archer himself becomes the arrow.

Mangoes are unusually stable coastal environments where

an Archer fish can focus on beating the competition.

But on the exposed coast of Mexico's Yucatan, life is precarious.

Concentrated by the tropical sunshine, the brine in these

shallow lagoons cannot be tolerated by most animals.

And yet these Caribbean flamingos have flown hundreds of miles together here.

These hypersaline waters keep many predators at bay.

So it's here they choose to nest.

There are more than 10,000 pairs here. It's the

largest breeding colony in North America. Nest mounds

keep chicks clear of the brine while they're still at their most vulnerable.

But this generation faces a problem.

The storms that come each season are arriving earlier every year.

And the colony lies directly in their path.

Rising winds create a storm surge that overwhelms the most exposed nests.

And then it rains.

The adults do what they can, bailing out their nests.

But they can only do so much.

The storm passes, but leaves devastation in its wake.

Most nests are submerged.

The chicks are soaked and cold and will soon

perish unless they can get out of the water.

The adults are unable to help.

A chick must save itself.

Some years, no chicks survive. The largest number of nests in this colony.

Our coasts are vulnerable places. Increasingly so,

as rising global temperatures create bigger storms.

The biggest are hurricanes.

They form over warm tropical water, building in strength at sea.

But their full force is unleashed on our coasts.

Where 40% of the world's human population have made their homes.

In this changing world, coasts are on the front line.

Rain Island. One of the planet's most important

breeding sites for one particularly precious species.

The green turtle.

On a few special nights each year, as many as 20,000 females come ashore here.

Their instinct to nest is strong. And many haul

themselves far inland in search of nesting space. In a

single night, they may lay as many as 2 million eggs.

Dawn.

This exhausted female has nested, but now she faces

a long return journey through the dunes to the sea.

As the sun rises,

she's at risk of being baked alive.

Every inch she travels is grueling.

And the ebbing tide has exposed a rocky reef.

It has already claimed many lives.

Other females overcome by heat and exhaustion.

Her temperature is rising. She has to keep going.

As many as 2,000 female turtles may die here. Each year,

each year.

But the coast is always changing.

And the turning tide may yet save her.

Half of all the girls. The green turtles in the Pacific come

here to nest as they have done for at least 1,000 years.

But for how much longer?

If sea levels rise as predicted within the next 30

years, Rain Island will disappear beneath the waves.

Coasts are dynamic, dangerous frontiers. And they're

changing faster than ever before in human history.

Life is remarkably resilient and adapts to new challenges.

But there is a limit on how fast it can do so.

As far as I know, I was one of the first people to film on Rain Island back in 1957.

After a fortnight of travelling north, we at last sighted

Rain Island. From the sea, it looked no more than a low

sandbank covered in scrub. But as we rode ashore, we were

deafened by the cries of thousands of seabirds which hung

above the island like a black cloud.

I was 31 and it was here that I first met a green turtle.

The turtles come up to lay at night. And after a night spent

laying maybe over a hundred eggs, she's very

weary and very anxious to get back to the sea.

Nearly 70 years later, the Planet Earth 3 team are welcomed

by people whose connection to the island goes back very much

further than mine. The Wotati and Miriam people have been

coming here for several thousand years. Rain Island is a

beautiful and special place. Like there's nowhere else on

the planet where you come and see this much turtles. It's a

wonder to see.

Since I was there, it's been discovered that Rain Island

attracts more nesting green turtles than anywhere else on

the planet.

So many, isn't it? As soon as you're up, you're like, oh,

there are a lot. And the crew soon meet some other residents

too. This is behind the behind the scenes.

See you, mate.

The team are here to record the mother turtles perilous journeys back to the sea.

Oh, God.

Trapped turtles can often free themselves with the help of

the rising tide. Nearly just a bit more to the right there.

But in this case, Tyrone makes the decision to intervene.

Ready? One, two, three. Anytime we're here, we'll walk the

beach, any turtles that have no chance of making it back to

the ocean. If we can save them, we save them because every

turtle is precious. At the time of my first visit, little

was known to outsiders about Rain Island. But for the last

few decades, scientists have been working with the Wutati

and Miriam people to understand more about this special

place. Scientists have been coming to Rain Island since

about the mid 70s. And over that time, they've been

monitoring the nesting population here. This work involves long hours.

98.7. And a certain degree of patience. Oh.

We're going to be wearing half of Rain Island by the end of tonight.

Helping the year's first hatchlings is a little easier. So

we'll take these ones down to the water's edge. So hopefully

we'll see these turtles back here laying eggs in 30 years

time. With the help of this dedicated team, Rain Island's

turtles might seem to have a good future.

But research is revealing a hidden threat.

The direct effects of climate change.

You want to hold this against the flat part of the daughter

logo? A developing turtle's sex is determined by the

temperature of its nest. Higher temperatures produce female

hatchlings. The temperature of the sand on Rain Island is

now at a record high. So 99% of the turtles that hatch here

are female. More alarmingly, we now know this has been the

case for at least the last 20 years. You do the math. All

females, no males. What's going to happen? There's going to

be a population crash and there'll be no more turtles.

Work is underway to find solutions. But that's not their

only problem. Not only are temperatures rising, sea levels

are too. Increasingly, high tides on rain are flooding many of the nests from below.

Drowning the developing turtles before they hatch. It's

really upsetting. You'll dig down to check to see success.

And you get down to the nest and you're just pulling up dead

eggs. To try and stop this happening, they have devised a

heavy-duty solution.

These machines have been shipped hundreds of miles from the

Australian mainland to reshape the beach. They have already

shifted sand that would fill 16 Olympic-sized swimming pools

and doubled the number of safe nesting sites. The hope is

that this will ensure that over 5 million more eggs will hatch in the next decade.

But from then on, the future of Rain Island looks very

uncertain. At this stage, we think that we have until about

2050 until we start seeing massive impacts of sea level

rise. It's crazy to think that, you know, the work that we

do here, someone might not be doing this in 30

years' time because there's no island to do it on.

What sort of world is it going to be for my children and

their children? Is there going to be anything for them? Or

is it all in vain?

We'll always be here fighting for Rain Island, the turtles,

but we can't do it alone. We need government and big

business to wake up and see what they're doing to the planet and get real.

This little fellow is newly hatched from an egg which had

been laid a month or so earlier, and he too is very anxious

to get down to the sea.

Having at last successfully reached the water, he's still

got a great number of hazards to face before he grows up.

Little did I know then what hazards he was going to face.

What hazards that little turtle would have to face, or the

extraordinary lengths to which people would go to protect it

and its island. In the 66 years since my visit, Rain Island

has remained the most important green turtle nesting site on

the planet. The question is, can it last another lifetime?