Original subtitles

A thousand kilometers on the march are facing

their greatest obstacle on their annual migration.

Tanzania's Mara River.

Traveling with them are zebras, some females with foals, and

waiting for them.

The smaller a foal, the lower its chances.

And he is one of the smallest.

He tries to stay as close as possible to his mother.

Those that get separated are unlikely to survive.

He's struggling to keep up.

All he can do is kick.

While others take the fall.

The distractions last just long enough to enable him to reach his mother.

Continuing their march with the planet's largest herd.

Some animals give their young the best start

in life, by making truly astonishing journeys.

And it's not only where they go that's important, but when.

Mexico's Pacific coast.

The beach looks deserted.

But beneath the sand, thousands of animals are on the move.

Olive Ridley Turtle hatch entrepreneur,

In October, the sand is at exactly the right temperature for an emergence.

The first to surface.

Stay still.

Any movement might attract attention.

They must wait for others.

They are about to start on the most dangerous journey of their lives.

And it's better to do that together.

For the hunters, this is the biggest feast of the year.

They take half of the emergence.

And they are catching hatchlings on the beach.

But the little turtles keep arriving in such

numbers that the predators simply can't keep up.

And that is their only chance of reaching the water.

The tide is going out.

Things are getting even more dangerous for the little turtles.

Their only chance is to follow the others.

Some reach the shallows.

But even now, they're not safe.

Those that survive will swim harder in the next 24 hours than they will ever do again.

As they travel, they are imprinted by the Earth's magnetic field.

A mental marker that will guide them back when it's their time to breed.

Every Olive Ridley turtle will spend the first 15 years

of its life in the Pacific feeding and growing alone.

Each will travel hundreds of thousands of kilometers.

Until one day, they change course.

And begin the long journey back to the beach where they hatched.

For the first time in over a decade, this

teenage turtle meets others of its own kind.

A quarter of a million of them.

The greatest gathering of turtles on Earth.

Here she will mate, then swim ashore to lay.

She is no longer a tiny hatchling.

But the shadows are still just as daunting.

The first she's touched in 15 years.

Now she has urgent things to do.

Her eggs are ready to be laid.

And she must dig a nest for them.

If she deposits them below the tide line, they would drown.

But too far up the beach, and they could dry out.

So the middle ground is very popular.

As thousands more adults arrive.

As many as 80% of the eggs laid here are

accidentally destroyed by other nesting females.

But so many eggs are laid.

That millions will remain undamaged deep in the sand.

She lays a hundred or so.

And with that, her work is done.

But next year, at this same time, she will

return to this particular beach to lay again.

And will keep doing that for the rest of her life.

Most of the journeys made in order to breed have barely changed for millennia.

In the remote part of the Atlantic, east of South America, lie the Falkland Islands.

Elephant seals have been coming here to breed for thousands of years.

Here, on this beach in late October, there are only pups.

Their mothers left them weeks ago and now they must fend for themselves.

In a few days, they too will leave and begin

their lives as ocean wanderers in the deep sea.

But they have yet to learn how to swim.

This sheltered beach-side pool would seem a good place to be.

But they have yet to do that.

They get acquainted with the sea.

They make the right swimming movements instinctively.

But are as yet unable to understand danger.

Orca.

Killer whales.

This is no passing pod.

They travel hundreds of kilometers to get here.

But at this precise time.

Twenty years ago, the lead female discovered when the pups go to their play pool.

And when, as the tide rises, she too could reach it.

Until then, she must wait.

If she mistimes her attack, she will get stranded on the rocks.

At half-tide, it's just deep enough for a killer whale.

She doesn't

recognize the threat.

Even when it's staring them in the face.

She needs a pup to be in the water.

But it's still dangerously shallow for her.

A wrong turn and she could get stuck.

The pups are almost within reach.

She watches and waits.

For one to come close enough to snatch.

She carries it, still alive, out to sea.

This female orca is the only one who hunts in this way.

And she does so for her entire family.

The pup remains alive for hours.

These orcas have learned to take advantage

of the seals' annual journeys here to breed.

And perhaps equally remarkably.

Know exactly when they should come back every year.

Breeding in safety for some animals means avoiding crowds.

New Zealand, the last habitable landmass to be reached by people.

To get here, the Polynesians had to cross thousands of kilometers of open ocean.

And so indeed does any animal.

But nonetheless, one visitor makes a 6,000 kilometer

journey across the Southern Ocean every year.

To the island's most secluded corners.

It's shy.

And mysterious.

It's a secret.

It's a secret.

Fjordland's Tarwaki penguin.

The Jungle Penguin.

He's looking after his eight-week-old chick.

While his partner is at sea.

Finding food.

If he doesn't do so adequately, she might leave him.

Penguin divorce rates are indeed high.

So he had better keep everyone away.

His partner has returned to the coast after a busy day collecting food.

But getting ashore is not easy.

It's a question of timing.

Almost.

Nicely done.

To reach her hungry chick, she has to travel over boulders, roots and ravines.

This is Deliveroo penguin style.

Dad can only watch.

And watch with envy.

As the chick grows, so too does its appetite.

To keep up with the demand, Mum must complete the obstacle course through the jungle.

Again.

And again.

To rear her chick, she will walk the distance of

a marathon and swim over a thousand kilometres.

And she will lose up to half of her body weight.

But that doesn't stop her.

And then, after ten long weeks, she's finally had enough.

With the delivery service ended, hunger drives the chick to the sea.

There's plenty of food to be had.

Just offshore.

But, strangely, he swims away with others and keeps

going for thousands of kilometres, halfway to Antarctica.

It's the longest single journey made by any penguin.

And, quite possibly, pointless.

It's thought their ancestors started doing this two

million years ago, when their food was only found out here.

And it's clearly been a hard routine to break.

In November, an increase in the daily sunlight

heats the Indian Ocean and kickstarts the monsoon.

In its path lies Christmas Island.

The rise in humidity it brings awakens a sleeping army.

Christmas Island Red Crabs now live on the island.

They now live almost entirely on land.

But to breathe, they still need moisture in their gills.

And the sea in which to lay their eggs.

So they make an annual trek to the coast, as they have done for 200,000 years.

Lately, however, a lot has changed.

But help is now at hand.

Local people have also built special bridges that allow

them to cross the busiest roads at their own speed.

And a network of subways guides them.

They increase their pace for them to catch the high tide.

In a single night, four million crabs reach the coast.

Each female shakes 100,000 eggs into the surf.

They hatch immediately and become free-swimming larvae.

Most years, the vast majority are eaten or washed into the deep.

And none return.

But with luck, on the next month's high tide...

they will be swept back to the island's shores.

Thousands of kilometres further south, another first journey is about to begin.

Late November.

Midsummer at the end of the world.

Patagonia.

The southernmost tip of the Americas.

Only one large land predator lives as far south as this.

This is Machito.

The grey one.

He is one year old and about to face the biggest test of his life.

Not that he knows it.

He and his sister, Niña, are at the age where they should separate...

and each find a territory of their own.

Competition between males means Machito is the only male...

and Machito will have to travel much further than his sister.

But now, each must learn to hunt.

Even for their mother... there is no greater challenge...

than catching an adult bull guanaco...

three times her size.

But she's an expert.

The cubs watch closely.

To succeed, she must get within a few meters.

And then hold on, no matter how wild the ride.

The cubs

should make the most of the free meal.

Their easy living is about to come to an end.

Their mother has done all she can for them.

After a year together, her territory is no longer theirs.

It's time for them to leave.

For several weeks, these siblings stay close to each other.

But they will soon need to go their separate ways.

Niña, the female, will be allowed to live close to her mother's home range.

Machito will not.

Male territories are much larger.

And to find enough space, he may have to travel for hundreds of kilometers.

For the first time in his life...

he is alone.

After weeks on the move...

he is starving.

He's seen how to hunt.

But has he learned enough?

Not quite.

To find food, he must keep moving.

Heading deeper... into unfamiliar lands.

He doesn't stop... until...

he picks up the unmistakable sense...

of a fresh kill.

But it was made...

by a huge male.

He's twice Machito's size...

and could kill him in seconds.

But he's too hungry... to give up now.

But he's too hungry...

Remarkably, the old puma backs down...

and allows the youngster to feed.

Behavior that is very rare among males.

Machito's courage may have bought him more time.

But his journey has only just begun.

But his journey has only just begun.

Male pumas travel far... and quickly.

As a consequence... very little is known... about their independent lives.

It's thought that few survive... their first year alone.

With luck... you'll be one of them.

It's Christmas Eve... and the shores of Christmas Island... are bright red.

Once in a decade...

the ocean currents are just right... for the crablets to return.

And this is one of the biggest... ever seen.

Billions crowd the reefs...

bewildering the locals.

They try to reach dry land...

in whatever way they can.

They need to get to the forest... from where their parents came...

and where they will be safe.

Just two kilometers away.

But their parents...

weren't the size...

of a pinhead.

Now they shed their shells... changing their wet suits... for something in which...

it's easier to breathe.

Ready.

But before they've even... left the beach...

they are attacked... by someone unexpected.

Mother?

Clearly... adult red crabs... are not very... child-friendly.

Time to leave the beach... and quickly.

That requires climbing... the sea wall.

As formidable... as the skyscraper...

would be for us.

Once at the top...

they must creep... through the town.

But it's hard... to keep a low profile... when you're part of an army...

of several billion.

The world... is very, very dangerous... when you're very, very small.

So they need... to watch their step.

The forest edge... safety... is in sight.

But it's too soon... to relax.

Yellow... crazy ants...

which eat... crablets.

Those that make it through...

are home... for Christmas.

They will spend... the next five years... feeding...

and growing...

before making... the return journey...

to the sea...

and then producing... little crablets... of their own.

An animal's... first journey...

will almost... always be... its most challenging.

But some...

are especially... daunting.

Young... demoiselle cranes...

face one of the... toughest migrations... made by any bird.

Fleeing... frozen Mongolia... they travel south...

to spend the winter... in India.

But the journey there... wasn't always... as hard as this.

45 million years ago... the land beneath them... was comparatively flat.

It was then... crushed... and pushed upwards... into great folds... creating...

what was to become... the highest mountain range...

on earth.

The Himalayas.

To cross... the cranes... must now ascend... to 8,000 meters... above sea level.

The higher... they fly... the lower... the oxygen.

Exhausted... they're vulnerable... to attack.

Golden eagles... lifted by the warm air... rising from the steep slope... soar...

above the cranes.

And then... they dive down... towards them.

To bring down... such large prey... the eagles... work as a pair.

This chick's... first journey...

has become... its last.

There are... lower... safer routes... than this.

But the crane's... instinct... is to fly... in the direction... they hope...

they have always taken.

Until very recently... they faced hunting...

and the loss... of many of their... traditional feeding sites.

Then... one small village... in northern India...

changed... their fortunes.

The people... of Kichang... began to feed... and protect... the cranes.

More... and more... cranes... arrived... each winter.

But...

15,000... of them... now visit... Kichang... every year.

It's... the greatest... gathering... of the species... to be seen... anywhere.

For the chicks... their journey... south across... the tallest... mountain range...

on earth... is finally... over.

Until... next year.

In... this... changing... world... animals... on the move... need... our help...

more than...

The tropical... forests... of Yunnan...

are the last... home...

of the endangered... wild... elephants... of China.

In March... 2020...

the forest... was hit...

by the biggest... longest...

drought... on record.

Trees... died...

and elephants... starved.

With a new member... of the family... about to be born...

the herd... decided... to move.

But... this... was to be... no ordinary... journey.

Their story... captured... the world's... imagination.

Here... was the... largest... land... animal...

trying... to find... somewhere... to live...

in the most...

populated... country... on Earth.

The family... headed north... into a very... different China... from the one...

they had left... behind.

For eight months... they trekked... through strange... new lands...

but couldn't find... anywhere... to settle.

So... their newest arrival...

was born... on the move.

That... for elephants... was highly... unusual.

His start... to life... would be very... tiring.

But the now... seventeen strong... family... had to keep... travelling.

And for those... who'd only just... learnt to walk... every hurdle... was a problem.

They couldn't... and every slope... a steep one.

They continued... for another... four hundred... kilometers.

And the further... north they trudged... the less... they belonged...

To eat... or drink...

they were forced... to steal.

But the... best friends... were cowards.

They were...

But remarkably, instead of driving them away, people gave them safe passage...

and allowed them to plunder.

After marching for a year, they were exhausted.

Elephants usually sleep on their feet and only

lie down when they are completely fatigued.

If we continue to change our planet, more and more

animals will be forced to make new journeys such as this.

But it was their next move that would be the most extraordinary of all.