All language subtitles for CD8ED50D75D9F9980B68A9D2D90B8F32_eng

Home to this Lausanne albatross chick.

He's ready to make his maiden flight to
the open ocean.

But there can be no room for error.

They've travelled a
thousand kilometres to get

here, arriving just in time
for the fledging season.

Leaving will be the most dangerous journey
of his life.

But it's his neighbours, black-footed
albatross chicks, that go first.

A splash landing.

Just what the sharks are waiting for.

Now it's his turn.

With the summer winds
picking up, conditions

are finally right for
him to spread his wings.

And fly.

He's airborne.

For the first time in his life.

But when the breeze suddenly drops,
so too does the chick.

Without wind, he's helpless.

A very lucky escape.

He's off.

He may not touch land again for five
years.

As he travels hundreds
of thousands of

kilometres across the
ocean, searching for food.

Our planet is solar-powered.

The sun's rays take eight minutes to reach
us.

But due to the Earth's tilt, they don't
strike its surface evenly.

This solar energy arrives in varying
amounts at different times of the year,

depending on where it strikes.

And in the Northern
Hemisphere, the huge increase

that comes with summer
triggers countless journeys.

In early July, the flower
meadows of Europe receive

more sunlight than at
any other time of the year.

And that makes it a very busy time for
honeybees.

Few animals work harder to exploit the
summer's riches.

To make just half a kilo of honey.

A colony of bees must fly 90,000 kilometres
and visit over a million flowers.

And we have taken advantage of their
labours for thousands of years.

In this domestic hive in
Germany, 60,000 bees

are working together
as one superorganism.

And with the larger queen
laying an egg every 30

seconds, it's a colony that
is now bursting at the seams.

There could be another 40,000 bees
developing in this hive.

And there just isn't enough room for them
all.

The superorganism has to split.

Those in the leaving party gather at the
entrance.

And when they reach a critical mass,
they begin to swarm.

They must find a new home.

But the first stop is just a staging post,
close to the hive.

In a few minutes, 30,000
bees gather around

the queen, who is now
shielded by the swarm.

Out in the open, they're vulnerable to the
elements.

So the race is on to find somewhere else
to live.

Scouts set off, looking for a suitable
home.

A tree hole that is just the right size,
height and angle to the sun.

This one looks possible.

But too shady.

Too small.

Already taken.

Now, what about this one?

It looks promising.

Yes, this will do nicely.

So it's back to the staging post to
convince the rest of the colony.

And she does that by dancing.

The angle of her waggle
dance relative to the sun

tells them in which direction
the hole can be found.

While the duration lets them know how far
away it is.

And the better the spot, the more intense
her performance.

Others return to advertise their finds.

But their moves just don't cut it,
compared to hers.

Interest grows around her.

And more bees set out to inspect the new
hole.

It's house hunting by committee.

It seems they agree.

And they return to spread the news to the
rest of the swarm.

To do so, the scouts must touch every bee
in turn.

And, incredibly, in just half an hour,
all 30,000 of them are ready to leave.

On arrival, each bee fans
a pheromone across the

forest, helping others
to find the new nest site.

More and more arrive at the new location.

All joining in to spread the chemical
message.

Within a few hours, the entire swarm has
made the move.

Bees are only able to move like
this when the sun's energy provides

them with enough food to
rebuild their colony from scratch.

So, for the next few weeks, they will need
to be as busy as, well, a bee.

In July, the further north you go,
the more daylight there is.

And for just a brief period, this increase
in solar power turns the Arctic tundra

into a rich grassland, attracting more
than a million snow geese.

They've travelled the length of North
America, a distance of 5,000 kilometres,

and they've come here to breed.

Arctic summers are short, so the geese
start laying straight away.

The female sits tight on the nest.

While the male keeps an eye out for
enemies.

And he doesn't have long to wait.

Arctic foxes live here the year round, and
they eagerly await the return of the geese.

The foxes' survival depends on a steady
supply of food.

And they're not afraid of eggs.

But snow geese only lay one clutch a year.

And they defend it with their lives.

Nonetheless, a single fox may steal over
1,000 eggs in a season.

Despite these losses...

...plenty of eggs do hatch.

It may be the height of summer,
but it's still the Arctic.

So the goslings stay with mother to keep
warm.

But there's only so much room under one
wing.

Still, it's better to keep out of the
way...

...when the tundra's larger residents pass
through.

Caribou themselves pose little risk.

But they do bring problems.

Grizzly bears follow them...
...in the hope of an easy meal.

And their presence causes a stir within
the colony.

Any chick in its path is hoovered up.

With things getting dangerous,
it's time to get out of the way.

It's time for these chicks to start their
life on the move.

The family heads for the safety of the
water.

In just eight weeks, when the sun's power
starts to wane here...

...the goslings will make their first
flight south...

...all the way to the Gulf of Mexico.

Not all animals migrate as the seasons
change.

Lions control the same territory year in,
year out.

So this pride in East Africa's
Serengeti...

...relies on prey coming to them.

Right now, it's the height of the dry
season...

...and the long grass plains where these
lions live...

...are relatively empty.

But things are about to change.

Heading towards them are hundreds of
thousands of wildebeest.

Together, they make up the biggest
terrestrial migration on Earth.

The herd eats its way through nearly 5,000
tons of grass a day...

...which means they have to keep on the
move.

Something the lions have been counting on.

The long, dry grass is of little
nutritional value...

...but the herd must pass through it.

And the lions know that.

The grass provides a very effective cloak
of invisibility.

To prevent her scent being detected...
...the lioness approaches from downwind.

Stalking...

...and stopping.

Every movement...

...considered.

One careless step...
...could reveal her presence.

Any disturbance in the grass... ...could
be a potential threat for the herd.

That's just a guinea fowl.

A false alarm.

Or... ...perhaps not.

She's almost perfectly placed.

Just 20 meters from her target.

After months with little to
eat... ...this is a vital meal.

The pride will need to make the most of
the migration...

...while it's passing through.

Soon, the herds will have left the lion's
territory...

...moving north in their never-ending
search... ...for fresh grazing.

In August, the Northern
Hemisphere... ...is at its warmest.

And on Canada's Vancouver
Island... ...there's one animal...

...whose life cycle depends on these
higher temperatures.

As day breaks over Cedar Lake...

...something is stirring in its depths.

Tadpoles here... ...spend their
nights hiding in deep, cool water.

Now, with the sun up...
...they set off across the lake.

Initially...

...in hundreds.

Then... ...thousands.

All are heading for the sunlit shallows.

Here... ...the water is five degrees
warmer... ...than in the lake's depths.

And that will speed their transformation
into toads.

But when night falls... ...they head
back... ...to the safety of the deep.

Until... ...the next morning.

Every day... ...they
repeat the journey.

Sun...

...swim...

...feed...

...repeat.

It seems perfect.

Except others take advantage...
...of their daily routine.

Dragonfly larvae.

They are ambush predators.

With extendable jaws.

And they have voracious appetites.

Blind leeches patrol the muddy bottom.

Once they catch something...

...they suck out its blood.

Throughout the summer...

...the tadpoles continue their daily
commute.

Until...

...after a few weeks...

...they start to look like tiny toads.

By harnessing the sun's
energy... ...they've grown quickly.

Now... ...they stop their daily routines...
...and prepare for their journey...

...into the forest.

Here too...

...predators await.

Garter snakes... ...specialize
in eating amphibians.

Though they rarely have
as much choice... ...as this.

Eventually... ...the sheer numbers of
young toads... ...overwhelm the snakes.

The survivors spread out... ...into
the forest... ...where they'll spend...

...the next four years.

Until... ...it's time for them...
...to head back to the lake...

...to breed.

By mid-summer...

...there is little snow left... ...in
America's Pacific Northwest.

Meltwater fills the rivers...

...ready to carry travelers...

...who make what is perhaps...

...the most extraordinary... ...and demanding
journey... ...tackled by any animal.

Sockeye salmon... ...and they're
heading upriver... ...to breed.

After three years feeding...
...in the Bering Sea...

...they find their way across...
...hundreds of kilometers of ocean...

...guided by the Earth's magnetic
field... ...and their astounding ability...

...to recognize the taste of the
river... ...in which they hatched.

They are one of the few fish in the
world... ...that can move from saltwater...

...into fresh.

And over the next month... ...they
will travel 200 kilometers upstream...

...past Lake Iliamna... ...to
their spawning pools just beyond.

It's the last journey...
...these salmon will ever make.

As they enter the river...
...they stop eating...

...putting all their efforts...
...into battling the current.

Swift rapids and high waterfalls...

...do not stop them.

Four weeks into their journey...
...their bodies begin to change.

Flashes of red appear in their flanks.

These are their breeding
colors... ...and the redder the fish...

...the fitter they are.

A few more weeks... ...and
they're barely recognizable.

The jaws of the males...
...have become hooked beaks...

...which they will use to fight for a
mate.

But their spawning pools... ...are
still nearly 100 kilometers away.

And just upriver... ...there are
predators... ...ready to intercept them.

Bears depend on the annual salmon run...

...to fatten up for the winter ahead.

Now

they're very, very hungry.

During the migration... ...an
adult bear can eat 40 salmon a day.

The salmon are quick and agile.

But as the water gets shallower...

...the advantage swings in favor of the
bears.

And the bears are not afraid...
Several kilometers upstream...

...the fish finally
reach... ...Lake Iliamna.

One of the last pristine
waterways... ...in America.

Their spawning pools lie just upstream.

But for now the sockeye linger...
...while the females' eggs...

...complete their development.

...are not yet over.

These waters are the home... ...of
the only freshwater seals... ...in America.

The salmon haven't
eaten... ...in eight weeks.

But they can still
out-swim... ...these predators.

The seals switch strategy...
...and start to hide... ...in plain sight.

In a rarely seen behavior... ...they
wait for the salmon... ...to come to them.

Surprisingly... ...they ignore the
males... ...right in front of them.

And go for the females... ...who
are laden with... ...calorie-rich eggs.

But for every...
...salmon that's taken...

...thousands... ...get through.

Mattered and bruised... ...from their long
journey... ...they have at last reached...

...their spawning pools.

Once here, males and
females... ...pair up and together...

...fight for the best nest sites.

They mate.

It's the only time...
...they will ever do so.

They've given everything...
...to complete this epic migration.

Their lives...

...the nutrients... ...from
their decaying bodies...

...fertilize the water.

A sacrifice... ...that ensures
the next generation...

...will have the very
best start... ...in life.

August in the... ...High Arctic.

After three months of continuous... ...daylight,
little is left... ...of the sea ice.

And that makes life... ...very
hard for this... ...ice bear.

And her eight-month-old cubs.

Three months ago... ...they were hunting
blubber-rich seals... ...out on the ice.

Now they're forced to swim...
...continuously for days on end...

...in search of... ...whatever
food they can find.

Polar bears use five times... ...more
energy when swimming... ...than walking.

And that is beginning... ...to
take its toll... ...on her smallest cub.

Oh!

He's finding it hard to keep up.

But his mother is too
hungry... ...to wait for long.

She can smell food
somewhere... ...on this island.

And the dive-bombing... ...gulls
are a sign... ...that she's close.

For the largest land carnivore...
...on Earth, these chicks...

...are not much of a meal.

Though they would be a
much-needed... ...boost for the cubs.

If they can get down
to it... ...before it's gone.

The weaker cub...

...is not very sure-footed.

By the time he's caught
up... ...it's too late.

With food... ...so scarce...

...there is no time for rest.

The climb back up...

...should be easy.

Certainly... ...his sibling
seems to take it... ...in his stride.

But after that long swim... ...the
weaker cub has little energy left.

Unable to follow... ...he panics...
...and heads in the wrong direction.

A slip here... ...would mean a
15-meter fall... ...onto the rocks below.

His mother takes no
notice... ...of his problems.

So desperate is she for another meal.

His survival depends... ...on
staying close to his mother.

If he can't keep up...

...she will be forced to abandon him.

He's made it...

...only to find... ...that he
must still... ...keep going.

It's a journey this young
cub... ...may not survive.

With summer sea ice melting
earlier... ...than we've ever known...

...polar bears are having to spend...
...more of their year swimming.

For animals... ...used to traveling
across ice... ...these changes may well...

...prove to be too great.

6,000 kilometers south of
the Arctic... ...the summer sun...

...is also heating the shallow
waters... ...of the Persian Gulf.

Making the sea here...
...the hottest on the planet.

Attracts the ocean's...
...biggest fish.

A whale shark.

After a journey... ...of
thousands of kilometers...

...it's arrived in time... ...for one of
the best feeding events... ...of its year.

And it's heading...
...to a particular spot.

The waters... ...of the
Al Shaheen... ...oil fields.

The platforms
act... ...as reefs...

...providing a home for hundreds...

No vessels are allowed... ...within
half a kilometer... ...of each rig.

So creating marine sanctuaries...
...where fish can spawn in safety.

Tuna are among them.

They can only breed...

...when the water is 25
degrees Celsius... ...or more.

So in summer...

...when the Gulf is at its hottest...

...they gather together...

...and release hundreds
of millions... ...of eggs.

The water's surface...
...becomes thick with spawn.

And that is what the whale
shark... ...has crossed oceans for.

Taking in water... ...through
its meter-wide mouth...

...it collects the eggs.

More sharks arrive...
...to join the feast.

And this... ...is the
hottest sea... ...on Earth.

And after feeding for a few
hours... ...each morning...

...the whale sharks will have to
return... ...to the cooler depths.

At the height of the spawning season...
...there may be over a hundred...

...per square kilometer.

It's one of the largest gatherings...
...of whale sharks on the planet.

And all the more remarkable...
...that it was only recorded...

...for the first time in 2010.

Back in the Serengeti...

...a million wildebeest and
zebra... ...are still on the move...

...following the sun and rain...
...in search of fresh grazing.

And in amongst the throng...

...new life.

This zebra foal... ...and his family...
...travel amongst the wildebeest...

...for safety.

He is just four weeks old.

And keeping pace with the
herd... ...is a daily struggle.

Yet his biggest hurdle...
...lies just ahead.

The Mara River.

Its fast-flowing waters...
...claim the lives of...

...a thousand animals a year.

Crossing it will be a major trial... ...for
a foal... ...that has never swum before.

The herd nears...
...the river's edge.

None wants to be the first to cross.

But as numbers increase...

...pressure mounts...
...on those at the front.

Once one commits...
...the floodgates open.

But the foal and his family wait.

Many wildebeest...
...drown in the crush.

Still... ...the zebra hold back.

And with good reason.

Five metre long Nile crocodiles...

...amongst the...
...biggest in Africa.

These giant reptiles... ...may not
have eaten... ...since this time last year.

With so many targets...
...from which to choose...

...they can afford to take their time.

Soon, perhaps...

...the crocodiles will have taken their
fill.

No such luck.

The zebra can
wait... ...no longer.

They must stay...
...with the herd.

So, the young
foal... ...must now...

...swim for his life.

... ... ... ...