Original subtitles

[narrator] Earth is a restless place.

[Thunder clapping]

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 crackling]

Nature marks the 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.

[Screeching]

[Squealing]

[Roaring]

Moment by moment,

month by month,

throughout A Wild Year On Earth.

Billions of years ago,

Earth was born from fire.

[Fireworks booming]

Today, fire heralds the New Year.

[Fireworks booming]

This is a time of extremes across the globe.

Both the height of summer, and depths of winter.

The seasons we've come to know

have strange otherworldly origins.

A planetary collision left our home forever skewed

at 23.5 degrees on its axis.

This small tilt has huge consequences

for life on the surface.

In January,

the southern hemisphere feels the full force of the sun.

Tilted away from the sun,

the northern hemisphere

is left out in the cold.

In the Arctic in January,

temperatures drop to minus 40 degrees.

[Cold wind blowing]

The days are at their shortest.

This is about as extreme a place, and season,

as any creature can endure.

Incredibly, this seemingly lifeless environment

has given rise to the planet's largest land carnivore...

The polar bear.

A male wanders alone,

fully exposed to winter's worst.

Half his bodyweight is insulating blubber.

Under his white fur is black skin,

to absorb what little solar heat there is.

[Triumphant music plays]

In this icy realm, he is king.

The residents of this frozen land

are not the only creatures coping with Arctic extremes

this time of year.

In January, the polar jet stream pushes south,

penetrating deep into North America.

This powerful front of fast-moving, frigid air

takes the Rocky Mountains firmly in its grip.

The snow lies almost a metre thick.

To survive,

animals must make snow an ally, not an enemy.

A normally nocturnal raptor has switched to daytime hunting

over winter.

The Great Horned Owl.

Its food options have decreased,

but its appetite has not.

It must eat 100g of meat per day to survive.

That's three voles' worth.

Unlike many tiny mammals,

the meadow vole doesn't hibernate.

Over winter,

it digs a labyrinth of tunnels under the snow.

Under the muffling blanket,

the vole makes the faintest rustle.

Even 20m away, the owl can hear it.

[Dramatic music plays]

The vole has acute senses and quick reflexes of its own.

But this game of cat and mouse is not over.

The vole has a weakness.

It doesn't stash food under the snow.

It needs a steady supply of seeds.

Getting food means breaking cover.

[Dramatic music plays]

[Vole chirping]

Riding the icy north wind, the hunter flies on.

Across the continent of North America,

the polar jet stream arcs south.

Out in the cold expanse of the North Pacific,

the jet stream's seasonal shift has a very different impact.

[Waves crashing]

A winter storm whips the sea into a frenzy.

[Suspenseful music plays]

Along the California coast,

rocky coves and bays offer shelter.

But there's no escaping the sea temperature,

which stays a frigid 12 degrees Celsius.

Fortunately, sea otters love the cold.

Many of Earth's creatures wait for warmer spring days

to breed, but not the otters.

They give birth when the sea is at its coldest.

[Gentle calming music plays]

In the aquatic maternity ward

are a rag-tag collection of pups of different ages.

This six-week-old was born during winter's first cold snap.

Safe on his mother's belly,

he gets acquainted to the world around him.

Teenagers play-fighting are the most entertaining.

Mum knows her pup is not ready

for such rough play.

But she agrees to give him a little independence.

It gives her a chance to attend to an important task.

Her fur is the densest of any animal on Earth,

double-layered with over 150,000 hairs per square centimetre.

Grooming releases natural oils from the skin,

to keep her coat waterproof.

She checks if her son's picking up some tips.

Not bad.

Primping done, hunger calls.

Her pup's too young to join her hunting,

but he can't be left to drift alone.

So she ties him up for safe keeping.

Sea otters use kelp strands

to anchor themselves in the swell,

and to keep unattended pups from floating away.

[Squealing]

Mind at ease, Mum takes the plunge,

to forage in the kelp beds below.

Winter's nutrient-rich waters swirl up from the deep

and flow into Monterey Bay's submarine canyon.

Countless marine creatures thrive,

including this spiny army.

Sea urchins eat kelp.

Thankfully, sea otters eat urchins.

Mussels are also on the seafood buffet.

[Crunching]

The mother sea otter takes her time foraging

and returns to the surface clutching her favourite meal...

Butter clams.

This was a good haul.

Hunger served, she looks for her pup.

He is untethered from his kelp,

but thankfully,

his fluffy fur acts as a life vest.

She gathers him onto her belly,

safely back where he belongs.

[Emotional music plays]

Not all marine mammals

need to be as hardy as the sea otter in January.

Winter waters are milder on the opposite side

of North America.

On the east coast,

the Gulf Stream flows from the tropics

along the Atlantic seaboard,

keeping both air and sea temperatures balmy.

Humans flock to Florida, the sunshine state,

for their winter holidays.

Manatees do too.

Some travel over 600 kilometres to escape the cold.

Despite their fat appearance, they lack insulating blubber.

If the water is colder than 20 degrees,

they cannot digest food or maintain body temperature.

But sharing the winter holiday with humans

presents another danger.

[Engine revving]

Boat strike is common.

And most manatees bear propeller scars.

[Sad music plays]

It's the last winter holiday here for this old soul.

Her injuries have proved too much for her.

Despite the dangers, the manatees return each year.

Up to 6,000 manatees congregate in the area.

But as winter deepens,

even the sea here can get too cold for them.

So they push on further, up creeks to shallow springs,

where temperatures remain a stable 22 degrees.

And where they're also protected from boats.

Calves of different ages

take the journey with their Mums.

They nurse as they go from a teat in Mum's armpit.

And they learn as they go, too,

about what their bodies need

and how they must travel with the seasons.

It's the first journey for this young manatee.

Over her lifetime

she may take the trip up and down Florida's waterways

60 times.

Across the globe,

other creatures also escape winter's extremes.

The influence of the Gulf Stream

extends beyond the shores of the Atlantic coast,

right across into Western Europe.

In January,

winters can be milder here than similar latitudes.

Brent geese know it well,

flying to the coast of France each January.

Compared to their homeland of Siberia,

this is blissfully warm.

Travelling deeper over the continent,

winter temperatures plummet.

In the Bavarian Alps,

the coldest days of the year drive people indoors

to escape the sub-zero temperatures.

Hiding to survive winter

is a strategy shared by many creatures.

In a tiny den, under frozen ground,

it's warm enough for eggs to incubate

under heavy guard.

It's the precious brood of a mother earwig.

She works tirelessly, turning to keep the eggs damp,

cleaning to prevent mould.

When you have 60 eggs,

each the size of a matchstick head,

that's a lot of work.

Her maternal dedication is a rarity in the insect world

and she will keep it up until the next generation hatch

and emerge.

Through thin eggshells, tiny brown eyeballs appear.

Sensing this pulse of life,

a predatory spider enters the chamber.

The mother earwig detects the trespass

and won't tolerate it.

[Suspenseful music plays]

The spider is banished back outside, into the deep freeze.

For another three weeks,

the mercury continues to plummet

to sub-zero temperatures.

Above ground,

the world is kept in suspended animation.

But below ground, there's an awakening.

[Unsettling music plays]

The earwig nymphs grow quickly,

and moult regularly.

Each moult leaves them darker, like their mother.

But unlike their mother,

the young don't waste energy protecting family.

On the contrary,

unhatched siblings offer a macabre game of soccer.

And supper.

This meal is good for now.

But winter is long.

They turn to Mum for more food.

But she only has one thing to feed them.

In a final act of maternal care,

she makes the ultimate sacrifice.

Offering her young the vital calories

and protein needed to survive till spring.

By late January,

much of east Asia is also in winter's grip.

[Wind blowing]

The temperature in Siberia

can plummet to minus 60 degrees centigrade,

and bitter winds race across the frozen lakes.

The wind gathers moisture

as it travels over the Sea of Japan.

Colliding with the steep mountains of western Japan,

the winds lift and dump great powder kegs of snow.

Japan can be one of the snowiest places

on the planet.

Not the typical spot to find a monkey.

Japanese macaques

are the world's most northerly species of primate,

other than people.

Feeding from winter's larder can be tough.

Sometimes it's just a lot of digging

for an ice-encrusted bug,

or a bit of bark.

In driving snow, it's hard for fur to dry.

As body temperature falls and stress rises,

there's only one thing to do.

Hit the spa with a group of friends.

Hot springs can be 50 degrees warmer than the air.

It seems to induce a zen-like mood among the macaques.

The troop bathes for hours on end.

Their preference for communal living

is a primate habit,

one we humans have taken to the extreme.

[Fast-paced drumming music plays]

Hundreds of millions of people are on the move,

to reunite with generations of family

for the Chinese New Year.

It's the largest human migration on the planet.

From Shanghai to Beijing, cities alight.

For two weeks,

people come together to see dragons dance.

[Fireworks booming]

The dragon symbolizes good luck.

To be in its presence is to be blessed with happiness

and fortune for the coming year.

Chinese New Year marks the second new moon

after the winter solstice.

It signals spring is on its way in the Northern Hemisphere.

Crossing the equator to the Southern Hemisphere,

intense solar energy is driving another phenomenon.

In February,

the path of the sun over equatorial Africa

bakes the landmass.

As heat rises, moisture and winds converge,

forming an immense tropical rain belt.

Marching across the continent,

vast quantities of water are on the move.

It's an event known simply as The Wet.

In the southern African country of Zambia,

the same amount of rain falls in January and February

as the entire rest of the year.

[Rain pouring]

Hippos are happiest in the wet season.

February is mid-calving time.

A big responsibility for this first-time Mum.

Only a few weeks old,

the calf is entirely dependent on Mum

to tell him what's what in this water world.

[Suspenseful music plays]

They look dangerous.

Mum barely reacts.

An adult hippo like her is too big and strong

to be considered a crocodile meal.

And in the wet season,

there's plenty of room in the pool

for everyone to keep a safe distance.

But those unblinking eyes, are disconcerting.

Mum decides a breather ashore is not a bad idea.

The calf stays close to Mum.

The bond between them is intense

and can last for six years or more.

He depends on her for protection.

Danger lies everywhere.

Lions on this river are specialist hippo killers.

It's hard for the inexperienced Mum

to judge where her calf is safest.

She makes the choice most hippos make.

She mistakes her own personal safety as safe.

The bystanders have a sense of what's unfolding,

but the calf is too naive.

By the time the mother realizes

her terrible error of judgement,

it's too late.

[growling]

[Sombre music plays]

It's a heartbreaking outcome for the mother.

But with only half of all baby hippos

surviving their first year,

her loss is a reality she may experience

many more times.

[Sombre music plays]

The wet season continues to wash across southern Africa.

[Lightning striking]

The giant herbivores gorge on all the fresh foliage.

Less than half is properly digested

by the time it rains back down on the plain.

The combination of A-Grade dung and high humidity

is a heady mix for one local.

When drops and plops knock on his door,

he hurries to answer.

For the copper dung beetle, this is heaven.

He spent the dry season underground,

in semi-hibernation.

The seasonal rain kick-starts his body into action.

[Buzzing]

While some rush to mate, he gallops past.

He wants to focus on creating his seasonal masterpiece first.

He fashions a brood ball.

It's the ultimate way to impress a female

and encourage egg laying.

He hurries to complete it and roll it away

before someone else steals it.

[Playful music plays]

He has a clear plan in mind and stops often

to check the position of the sun.

The problem with dung is that flies love it, too.

Given a chance

they would contaminate his ball with their eggs,

so they have to be shooed away.

[Playful music plays]

He checks his coordinates one last time.

In the distance, he spots his destination.

Soft soil, a bit of grass.

Perfect.

He digs deep,

ensuring his ball and any egg laid within it stays safe,

as wet season turns to dry.

February is a time of calm seas

in the equatorial waters around Indonesia.

Here is the meeting place of two major oceans.

Water flows from the Pacific into the Indian Ocean

through thousands of beehive islands.

This convergence

results in a dynamic tropical eco-system,

with Raja Ampat, its crowning jewel.

Under the surface,

strong currents churn nutrients and plankton blooms.

This soup of micro-organisms

supports the entire oceanic food chain.

Dense schools of baitfish attract a squadron of predators.

Devil rays.

These specialist fish eaters

will travel hundreds of kilometres

in the pursuit of this seasonal bounty.

In groups of 30 or more, they scissor the blue.

Their tight formations herd the frightened baitfish.

Light, agile bodies

with swept-back wings like a jet fighter,

can accelerate from cruise to attack speed in milliseconds.

[Intense music plays]

Out of the blue,

an oceanic manta ray arrives, with hitchhikers in tow.

This is the world's largest species of ray.

Wings propel its two-tonne body lithely through the water.

Most of the year, it prefers to travel solo.

But at Raja Ampat,

the season's nutrient-rich waters draw individuals

to feed from far and wide.

They mingle with the resident reef manta rays.

It's a rare time of year

when both species converge in the same waters.

With filter feeding mouths agape,

they ride the currents like magic carpets.

To the south of Indonesia lies Australia,

a continent where summer means extreme heat.

Soaring temperatures over 40 degrees Celsius

send people surfside to cool off.

At this time of year,

Australia is one of the hottest places on Earth.

Inland, no rain has fallen for months.

Australian summers are becoming hotter,

drier and deadlier as global temperatures rise.

[Lightning striking]

Dry lightning connects to the tinder-dry grass.

A spark becomes an inferno.

[Dramatic music plays]

Whilst most scramble to escape,

an aerial predator swoops closer.

[Screeching]

The black kite.

A creature who deliberately seeks out fires.

This bird is perhaps the only Australian

who welcomes the fire season.

Drawn by the smoke,

others converge from kilometres around.

[Dramatic music plays]

As the fire simmers down, competition flares.

Less fire, less food.

One black kite is still hungry.

Both phoenix and pyromaniac.

What it does next is the stuff of legend.

Aboriginal Dreamtime calls the kite, 'Fire Hawk'.

Like humans,

it harvests fire for personal gain.

What it hopes to gain now is grasshopper.

[Dramatic music plays]

satiated, the kite flies on,

spotting new fires as deftly as any satellite.

Parched inland Australia stands in stark contrast

to the jungles of South America.

In February,

it's the dry season in the Amazon rainforest.

But dry is a relative term.

The jungle still gets heavy downpours.

As quickly as the heavens open...

[Drum and claps]

..they close again.

[Drum and claps continue]

With a break in the weather,

leaf cutter ants pick up the pace

along their mass highway.

[Upbeat music plays]

The buttercup tree is flowering, an annual seasonal harvest.

Ten million ants join the foraging parade.

It's a rush to get nutrition

to their subterranean algae gardens

before the next downpour.

In Rio de Janeiro,

humans celebrate this season with Carnivale,

an annual festival

celebrating abundance before abstinence.

Both events require intense preparation,

teamwork and synchronization.

It's a wild climax to the start of the year.

Our planet completes its first 60 degrees of revolution

around the great ball of fire.

In the months ahead,

more profound change awaits the planet's inhabitants,

for change is the one constant

during a Wild Year On Earth.