Original subtitles

[narrator] Earth is a restless place.

[lightning striking]

Its seasons driven by the orbit around our sun.

An epic journey that sets the rhythms of all life.

Humans honour this passage through ritual

and celebration.

[fireworks blasting]

Nature marks this cycle

with its own patterns.

[bats chittering]

Over the course of a year,

the planet's most spectacular events of migration,

rebirth and transformation unfold.

Moment by moment,

month by month,

throughout a wild year on Earth.

It's spring time in the northern hemisphere.

A time of renewal.

And nowhere is that more evident than here in Japan.

A wave of blossoming cherry trees,

known as the Sakura Zensen,

is slowly flowing north.

Like many beautiful things, it's transient.

Each tree only blooms for a few days.

For Japanese Buddhists, its ephemeral nature

signifies more than just the arrival of spring.

It also signifies the fleeting nature of all life.

For others, it's just a great selfie.

Every year, millions of people come here

to picnic beneath its flowering canopy.

As spring brings this glorious burst of life

in the south of Japan,

a more subtle awakening is happening further north.

Here in the volcanic lakes of Hokkaido,

whooper swans have been resting over winter.

This white, frozen world

is where they've come to find warmth.

But Hokkaido is not only a land of ice.

It is also one of fire.

Powerful volcanic thermals underground

release heat in surface pools.

The water here can reach a steamy 50 degree Celsius.

The swans are known locally as, 'the angels of winter.'

Their time here has come to an end.

As the days get longer, they're called northward.

Flying almost 3,000 km from Japan,

their breeding grounds in Siberia.

[heroic music playing]

And they're not the only travellers.

All around the world,

animals are on the move,

driven by seasonal forces bigger than us all.

In Southern India,

it is the middle of the dry season.

There has been little rain for two months.

Food and water is becoming scarce.

A problem for those with big appetites.

At 50 years of age,

this Asian elephant matriarch

is the oldest member of her herd.

She knows that without fresh grass,

the other mothers won't have enough milk

for their calves.

She must lead them to the last remaining wetlands,

over 160 km away.

She learned the path from her mother.

[heavy string music playing]

Now, she'll teach it

to the newest member of her troop.

Her own grandbaby.

Long the Kabini River in Southern India,

other matriarchs are leading their families

on their own journey.

It is a migration guided by memory,

through a landscape with very few landmarks.

It's a lot for a new elephant to take in.

[fun upbeat music playing]

As the waters dry up,

the mothers are keen to move the youngsters on.

No matter how tired of marching the little ones are.

Thankfully, the journey is almost at an end.

The destination at last.

The lush pastures of the Kabini River.

The shrunken river has transformed the plains

into a carpet of abundant grass.

It's a welcome feast.

Elephants from across the region all converge on these plains.

They form one of the largest congregations

of wild Asian elephants known on Earth.

Their remarkable memories

mean they can recognize old friends

they haven't seen since last dry season.

Touching expresses reassurance, affection and affiliation.

The reunion will continue until the rains come,

and fami

ly groups will disperse once again.

The elephants aren't the only ones gathering

to celebrate seasonal change.

All across India,

people are coming together to take part

in an ancient ritual.

[cheering]

The Holi Festival.

Otherwise known as the Festival of Colours.

It marks the coming of spring to the sub-continent.

[hand drumming]

[cheering]

As the people celebrate,

a reclusive creature emerges.

The king cobra.

A loner by nature,

this snake shuns company.

Except for this one time of year.

The male is hunting for more than food.

[squawking]

March is cobra mating season.

He's tracking a female's scent,

a skill which can lead him up to 14 km in pursuit.

He's found another,

but it's not a female.

It's a rival.

A male following the same scent.

He has to deal with this head-on.

Fangs are of no use.

[hissing]

They're immune to each other's venom.

He tries to intimidate his opponent,

rearing up to show his size, but they're an even match.

There's only one way to resolve this.

[dramatic music playing]

This is a competition of brute strength.

[hissing]

After two gruelling hours,

the rival has had enough.

The victor has no time to waste.

Close by, the female is waiting to mate.

And the exhausted male obliges.

Thankfully, this wrestle won't last several hours.

When breeding season is over,

they'll go their separate ways and once again,

become reclusive.

Life on Earth is governed by the sun.

Its journey across the sky

divides our world into day and night.

In March there comes a day, perfectly balanced.

12 hours of dark,

followed by 12 hours of light.

It's known as the Equinox.

In Europe,

it marks the official start of spring.

Vast parts of the Netherlands

are transformed into a sea of flowers.

It's a continent in bloom,

that attracts one of the world's

most important environmentalists.

Bees link two of life's great kingdoms.

The plant and animal world.

Plants use the sun's extra energy to power their flowers,

and bees waste no time in making honey

from their nectar.

It's a relationship that started some 100 million years ago.

Bees have to visit over five million flowers

to produce just one kilo of honey.

Without them, spring's burst of colour,

and most of human agriculture

would simply cease to exist.

Travelling east across the continent of Europe,

the high mountains

are the last place to experience

the transformative power of spring.

A world once covered in snow

is now a sea of green.

In the Carpathian Mountains of Romania,

a pack is on the prowl.

[howling]

The scent of prey is on the breeze.

Wolf hunts usually end in failure.

But today,

they are in luck.

[dramatic music playing]

[growling]

They have caught a young buck.

[growling]

Wolves are highly social

and they will share their prize with the pack.

The newest members depend on it.

Wolf cubs are reliant on their mothers.

She needs the pack to bring her food to enable her

to care for her young.

Only the dominant male and female get to mate.

The survival of the entire pack

depends on protecting this one precious litter.

It's a successful strategy.

There are now 17,000 wolves roaming free across Europe.

And those numbers are increasing.

The arrival of spring

is less obvious in other parts of the world.

In the deserts of California, the scenery appears unchanged.

Yet here, too, the season brings new life,

if you know where to look.

For the Californian burrowing owl,

the desert is a perfect place

to dig a home.

A hiding spot

from coyotes and hawks.

Few birds burrow,

but in the desert,

it provides the perfect protection

from the soaring heat.

And while spring may not bring rain,

its warmth brings something just as good.

The darling beetle grub is a seasonal delight.

Burrowing owls are one of the few owls

that hunt by day and night.

In a world with limited food,

it's a successful evolutionary adaptation.

Beetle grubs provide

a feast for a king.

The only thing that would make it better

is a queen.

[calling]

Late March is the owl's breeding season.

[calling]

However, burrowing owl numbers are diminishing.

All too often,

the bachelor's calls go unanswered.

[calling]

This is a sound of a species

on the brink.

[calling]

[heroic music playing]

A female has heard his call.

And she has taken to higher ground.

It is a risky strategy.

But it pays off.

Having answered the call,

the couple settle in for the breeding season.

She will lay every day

until she has a clutch of up to 12 eggs.

Across the natural world,

other birds are pairing,

delivering a springtime egg bonanza.

[chirping]

As a symbol of rebirth,

the egg has taken on seasonal significance

in the human world as well.

As children delight

in the annual ritual of the Easter egg hunt.

[ringing]

For others, the seasonal rebirth

is a time of contemplation.

Easter is celebrated

by two billion people around the world.

In Latin America, it's known as Semana Santa.

Holy Week.

Since the 16th century,

the story of the resurrection of Christ

has been told through processions

through the streets.

It is the largest

and most important festival in the Christian calendar.

A celebration of life over death.

Religious undertones echo throughout South America.

Even in the wildest of places.

When 15th century explorers entered these jungles

for the first time,

they came face-to-face with a curious little monkey.

With their coloured cap of hair,

they were thought to resemble Capuchin monks

in their robes and hoods.

So they were named capuchin monkeys.

As the dry season comes to an end,

most capuchin babies

are born in the Amazon jungle.

This troop consists of a dozen related females,

their brand-new offspring,

some young males

and the alpha,

enjoying the perks

of his status.

By April, juicy mangoes, figs and fruit

have all withered away.

Reluctantly,

the

troop is forced to move to the forest floor for foraging sessions.

They hope to find

morsels of seeds and insects.

But it's risky.

Predators are lurking.

[screeching]

Once the sentinel

raises the alarm,

the troops scurry to safety.

It takes a lot

to outsmart a capuchin.

They are considered the most intelligent

of the New World monkeys.

Soon, they've discovered a safer source of food,

a late-blooming fruit tree.

But even here

in the canopy,

they can't drop their guard.

A neighbouring troop moves in,

looking to expand their territory

in these lean times.

But there's not enough food for everyone.

They'll have to evict the residents.

The rivals will kill

any offspring they can,

so the lives of the new-bornsare on the line.

[intense music playing]

The troop's only defence now is in unity.

With the Alpha leading the charge,

the females back him up.

[screaming]

Driving away the assailants,

the resident troop have held their ground.

Females will attend to the wounded alpha,

and the troop settle nerves with some grooming.

With the rains approaching,

the capuchin troop have made it through

the hardest part of the year, together.

Across equatorial South America,

the dry season has the land in its grip.

With the converging trade winds

still far to the south,

the engines that drive rainfall are absent.

Four months without rain

has transformed what was once lush grasslands

into a parched landscape.

Rivers have disappeared, lakes vaporized in the heat.

The barren ground cracks open.

The lack of water

forces one of Colombia's most peculiar inhabitants

to congregate.

Capybaras are the world's largest rodent,

twice the size of a beaver.

They're usually found in small family groups

and establish separate territories.

But at this time of year,

they put their differences aside.

Following the wet scent of mud,

they coverage on the few remaining sources of water.

At the height of the dry,

they gather in herds of over 100.

Capybaras submerge to keep their skin

cool and moist.

Mud does the trick, too.

It's why they're also known as, 'water hogs.'

And this is hog heaven.

These water-loving rodents

can spend just about all day soaking.

Together, they'll stay here till the rains return.

For animals that like to keep their distance,

they're surprisingly chatty.

[grunting]

Not only do capybaras bark,

but they purr, chirp, click, squeal, whistle and grunt.

[grunting and squealing]

For others on the Llanos,

there is no escaping the seasonal cacophony.

Until the rains come,

they're stuck with their noisy rodent neighbours.

Life on the equator

is not marked by seasons such as spring and autumn,

only wet and dry.

The sun strikes equatorial lands at a similar angle all year,

creating the constant pulse of 12-hour days and nights.

But it's the rhythm of the rain

that sets the timing of rebirth.

[rain pouring]

In equatorial Africa,

animals coincide the arrival of young

with this time of plenty.

A baby impala is on her feet, moments after birth.

It's a precarious time.

African wild dogs casually linger close by.

The impala can't afford to flee at the sight of every predator,

so they remain alert, but not panicked.

And yet, an attack can occur

at any moment.

[dramatic music playing]

There is no plan,

no teamwork or single target here.

It is every dog for itself.

[dramatic music playing]

In the chaos,

a mother has been separated from her young.

Too far away to hear her mother's call,

the calf is confused and exposed.

But impalas have a secret super power.

Hidden in the black tufts of their heels are scent glands.

Impalas have a unique leap,

specially evolved to spread their odour.

The females create a scent trail

and the rest of the herd help, too.

[heroic music playing]

It's all the calf needs to find her way home to her mother.

And the safety of the group.

Across the globe,

atmospheric shifts set animals in motion on land and undersea.

In the Western Pacific Ocean,

strong seasonal currents

converge on the archipelago of Palau.

April is the time great schools of grey reef sharks

converge en masse in the island shallows.

They time their arrival with the spawning

of schools of red snapper.

Mass congregations also make it a convenient time

for grey reef sharks to mate.

For the white tip reef sharks,

sex is also on the menu.

When a female is fertile, packs of males start to circle.

Biting her pectoral fins,

the gang pin her

to the sea floor.

The male's sex organ is known as a siphon sac.

It inflates by sucking in sea water

before he flushes his sperm into her.

Females are covered in scars from these brutal encounters.

Mating is as quick as it is fierce.

When it's finished,

she'll be left alone.

[sombre music playing]

The white tip reef sharks remain resident

in this super-productive tropical environment.

But many other ocean wanderers simply pass through

as they drift on currents

transporting them across the Pacific.

Ocean currents act as watery highways,

circulating the sun's heat across the globe.

Heat is transported from tropical regions

towards the poles,

via boundary currents,

such as the East Australian Current.

By April,

this current is starting to slow down

as the trade winds change.

Throughout the summer,

marine turtles have used this fast-flowing highway

to hitch hike to the Great Barrier Reef.

[intense music playing]

It's late in the season.

And this female is one of the last to arrive.

Having spent the last five years wandering solo,

her ripe brood of eggs have urged her to head home.

It is no easy task.

But it's worth the effort.

Tonight, she will lay over 100 eggs.

The nest has to be just right.

Too deep and the babies won't be able to escape.

Too shallow

and the hot sands will bake them.

Like all things in nature, it is a delicate balance.

When she's finished,

she returns to the ocean.

Never to meet her offspring.

Even as she departs,

baby turtles that were laid eight weeks earlier

are already beginning to emerge.

They are driven by instinct towards the awaiting sea.

It is a dangerous journey.

Ghost crabs haunt the shores.

This is the most perilous five minutes of their lives.

Flapping flippers

are their only defence.

[dramatic music playing]

But sometimes,

they just get lucky.

Only 1 in 1,000 turtles will reach maturity.

Those that do

may live to be over 80 years old.

They will go with the flow of the currents,

drifting thousands of kilometres from their home beach.

To one day ride the ocean highway

back to the same islands to complete the cycle.

On the opposite side of the Australian continent,

the changing trade winds mark the end of the wet season.

In the tropical north-west,

rivers carve through rocks,

1.7 billion years old, on their journey to the sea.

In April,

tides reach a height of almost 12 metres.

[water crashing]

The ebb and flow is so large,

it creates horizontal waterfalls.

As much as a million litres of water

pours through these gaps

every second.

As the water recedes,

an alien landscape is revealed.

As hundreds of kilometres of mudflats

appear along the Kimberley coast.

The sludge teems with a medley of life.

From tiny mudskippers,

to huge monsters.

It is a rich muddy soup,

much like the primordial ooze,

from which life on land first emerged.

It now supports those that have evolved

to fly.

The Kimberley coast is home

to the greatest diversity of shorebirds in the world.

Curlews, sandpipers,

stints, terns, tattlers and a multitude of others.

Soon, these flocks will leave for their breeding grounds

in Siberia,

prompted by the shorter days and change of seasons.

They need to fatten up before they depart

on the longest migration attempted

by any creature on Earth.

To reach the Arctic, 25,000 km away.

As the Earth continues its journey around the sun,

the southern hemisphere

autumn stretches into wintertime.

As the sea ice forms

and expands around Antarctica,

the continent doubles in size.

The edge of the ice advancing up to four km a day.

This seasonal change heralds the arrival of a royal.

[majestic music playing]

By the end of April,

Emperor penguins make the change from ocean to ice.

After months at sea,

they head into the heart of the frozen continent

in search of a mate.

Their breeding grounds lie some 160 km from shore.

It's a cold march in bare feet.

Slowly, distant colonies begin to merge.

And the formal gathering

now numbers over 20,000.

[chattering]

They are finally at their breeding grounds.

[chattering]

Emperor penguins are serial monogamists.

Each year,

they have a chance to start again

with a new partner.

Only 15 percent will choose to return to last season's mate.

But once they've made their match,

they remain faithful.

At least till the summer arrives again.

The rhythms of nature continue to follow the pace

set by the Earth's movement around the sun.

These enduring planetary pulses hold all life in its grasp,

during a wild year on Earth.