[somber cymbal crash]
[David Attenborough] In 2021,
the world watched as a family of wild Chinese elephants slept,
exhausted after an epic 400-kilometer journey.
[poignant music playing]
Forced from their ancestral forests
by the worst drought on record,
the family had gone in search of a new home.
[music becomes hypnotic]
Having traveled through huge swathes of farmland,
there was still no sign of them stopping.
But what they did next surprised everyone.
[music climaxes, fades out]
Crossing under a five-lane highway,
the family approached the city of Kunming.
[elephant growls]
[siren in distance]
[dog barking]
Within days,
the elephants had reached the city limits.
[elephant roars]
[sirens wailing]
And they quickly found themselves in a frightening new world.
[elephant trumpets]
[horn honking]
[siren wails]
[elephant roars]
[elephant growls]
Scared and disorientated,
the family had no choice
but to turn around and begin the long march home.
[poignant music playing]
Remarkably, despite the damage they caused,
the elephants were not just tolerated by the local people
but helped,
with hundreds of thousands of dollars spent guiding them safely home.
After almost two years
and more than a thousand kilometers on the road,
the weary caravan arrived back in the southern forests,
where the drought had eased.
Against all odds,
this part of the family's story had a happy ending.
But it showed that when animals are faced with dramatic change,
the urge to move away can be overwhelming.
[music climaxes]
[music fades out]
[theme tune playing]
[music fades out]
[optimistic music fades in]
Our planet, traveling around the sun, is tilted.
And in January,
this means it's summer at the southern end.
Though, at the bottom of the world, that isn't always obvious.
[music fades out]
[lively string music playing]
Even in the summer's peak,
temperatures in Antarctica barely rise above freezing.
But with 24-hour daylight,
there's now just enough warmth to melt the sea ice around the continent.
[music climaxes]
[music becomes livelier]
And that is important for gentoo penguins,
who need to reach land in order to breed.
[music intensifies]
For the last few weeks, their lives have been driven
by a 30-kilometer daily commute
to their feeding grounds out at sea.
Now, with bellies full, they're heading back to their chicks.
[quacks, trills]
[quacking, trilling]
[chirping]
[chirps softly]
After a day in the water,
it takes a while to get their land legs back.
- [quirky music playing] - [squawks]
[cheeps]
[squawks]
Gentoos need rocks free of ice
on which to lay their eggs and raise their young.
So the home straight is often an uphill waddle
to the windblown clifftops.
[music abates]
[twittering]
Their chicks hatched eight weeks ago and are now nearly fully grown.
In Antarctica's short summer window,
they're right on target to fledge before winter returns.
[quirky music playing]
The chubbier the chick, the greater their demand for food.
[chicks cheeping]
And some parents seem reluctant to indulge them.
- [music accelerates] - [chirruping]
But there is value in this behavior.
By making the chicks work for their meal,
the adults are able to assess their strength...
[incoming chick caws loudly]
...their stamina,
and their coordination.
[chick 1 chirps]
[chick 2 chirps]
[music intensifies]
The prospect of food entices the chicks down to the water.
[music stops]
Though not quite into it.
It seems that even for a penguin,
the first step into cold water requires
a little courage.
[quacks softly]
[optimistic music playing]
But it just takes one to lead
for others to follow.
Shallow, sheltered pools are a safe way of testing their waterproof coats.
[quacking]
And with summers so short here,
they'll need them very soon.
[wind howling]
Before long,
the seas around Antarctica will be covered by ice once more.
[ethereal music playing]
So the young chicks must head for open water now if they are to feed.
But they're nervous.
[caws]
And for good reason.
[music becomes menacing]
Who wants to share the water with a three-meter leopard seal?
[squawking softly]
[snorts]
And not just one of them.
But three.
[warbling]
Like their namesake, they hunt by ambushing their prey.
And gentoo chicks make easy targets.
[squawks]
But regardless of the danger,
the penguins' need to feed is great.
[frantic string music playing]
Gentoos are the world's fastest penguins.
[music becomes sweeping]
[music becomes dramatic]
If they can avoid being ambushed, they have a chance.
The young penguins stick together for safety.
[music abates]
But in the confusion, a chick becomes separated.
It's now one-on-one.
[music reprises]
[music intensifies]
[music abates]
The penguin's only hope
is to rely on its great agility and stamina.
So the longer the chase, the better its chances.
[music reprises]
[music climaxes]
[music rapidly fades out]
[gentle classical music fades in]
This very lucky young penguin can now join the others.
And the open ocean awaits.
[music fades out]
[ambient music playing]
[music fades out]
[insects chirping]
In February,
the northern end of the planet points away from the sun.
- [hypnotic music playing] - [star whooshes]
[star whooshes]
So in the Arctic midwinter,
darkness is almost continuous,
with the only light coming from the aurora.
[music becomes spiritual]
These ethereal displays are created
as electrically charged particles from the sun
collide with the Earth's magnetic field.
This is the time when countless animals begin their long journeys
to these northern regions.
[music fades out]
[chirping]
Five thousand kilometers to the south,
snow geese have just started their annual migration.
[optimistic music playing]
[quacking]
Led by the older, experienced adults,
they follow the thaw as it spreads northwards.
And fly from the Gulf of Mexico
to their breeding grounds in the Arctic.
They will reach the tundra
just as the long days of summer create the perfect conditions
in which to raise their chicks.
[music intensifies]
They use natural landmarks, like lakes and rivers,
to prevent them straying off course.
But today,
the world beneath them is very different
from the one over which their ancestors flew.
Where there was once endless savanna,
there's now industrial farmland.
[chorus of squawking]
[music ends]
But that is not necessarily a bad thing for the geese.
To reach the Arctic,
the flocks need to refuel regularly along the way,
so the fields of America's breadbasket country
have become vital pit stops.
[hypnotic music playing]
This near-endless supply of food
has meant that the snow geese population
has doubled in the last 50 years.
But there's a cost to becoming one of the world's most numerous goose.
[squawking]
[squawking stops]
Not everything in this modern world is as it seems.
- [tense music playing] - [metallic ticking]
[squawking]
[music intensifies]
- [gunshot] - [music fades out]
A quarter of a million are shot each year.
[stillness]
[jaunty music fades in]
Snow geese have to run the gauntlet of hunters along much of their route.
But sandwiched between two of America's migratory flyways
lies a patch of wetland, where they're protected.
[music intensifies]
Missouri's Loess Bluffs.
It's one of the most important stop-off points
on their long journey north.
[chorus of squawking]
How long they will stay depends on the weather.
In February, icy winds blowing down from the Arctic
can cause temperatures to suddenly fall.
And if it's freezing here,
conditions will be far worse where they're headed.
So, for now, all flights north are suspended.
[quirky music playing]
They may be snow geese,
but they don't seem to be at home on the ice.
[falling goose squawks]
With the lake's margins frozen,
the birds become concentrated in the center.
The busier it gets, the less room there is for maneuver.
[chorus of chirping]
And that suits another visitor.
[menacing music playing]
Bald eagles come here...
[screeching]
...from across North America.
And they time their arrival to coincide with that of the snow geese.
[music becomes unsettling]
[jarring violins playing]
[honks]
[violins become more frantic]
[music becomes dramatic]
The geese are far too big to be snatched on the wing,
so the eagles use a different hunting strategy.
Flying at the flock, they scare the birds into the air.
The tighter the geese are packed, the better it is for the eagles.
[music intensifies]
In their panic, geese collide with one another,
and limbs are broken.
Injured birds are left high and dry on the ice
or unable to escape underwater.
[music stops]
[eagles squawk]
All will remain vulnerable for as long as this cold snap lasts,
their onward migration still blocked by ice and snow.
[ambient music fades in]
Back in the Arctic, the sun is slowly beginning to strengthen.
But in late February,
its rays still barely show above the horizon.
In such frigid conditions, there's little to eat,
and most animals retreat southwards
or shut down altogether.
But this one does neither.
A lynx, the most northerly cat in the world.
[music becomes ethereal]
It's well protected from the cold, so it doesn't retreat.
But it may have to travel huge distances to find food.
[music becomes hypnotic]
One was even recorded
walking more than 3,000 kilometers in just one year,
further than anyone thought possible.
This cat relies almost entirely on just one kind of prey.
And right now, there are very few around.
[sinister music playing]
Snowshoe hares.
Spotting one is only half the challenge.
[music becomes dramatic]
[music fades out]
[purring]
[soft whimsical music playing]
[purrs]
Lynx need to eat every few days,
so his search never ends.
He's in luck.
[sniffs]
He has detected another scent.
[music becomes tense]
[in hushed tone] The hare holds its nerve
and trusts its camouflage.
The lynx can't outpace his prey over a long run,
so he needs to get close.
[music becomes dramatic]
[music climaxes]
[music ends]
A meal at last.
[ambient music playing]
[music becomes optimistic]
As the Earth's Northern Hemisphere tilts back towards the sun,
bringing the longer days of March,
pronghorn antelope start their annual migration.
Their journey will take them from the snowy plains of southern Wyoming
to the lush valleys of the Rocky Mountains,
where they will give birth.
[music fades out]
[snorting]
But today, their path has changed beyond recognition.
And to start with, they have to find a way through oil and gas fields.
[sprightly music playing]
A male tries his luck.
[music intensifies]
[music abates]
[snorts]
Pronghorn are cautious,
especially when encountering humans.
[woman speaking over two-way radio]
[pipe clanking softly]
[tense music playing]
[in hushed tone] So far, so good.
Now for the rest of the herd.
And...
go!
[dramatic music playing]
[music fades out abruptly]
Over the next couple of months,
they will travel 200 kilometers
to reach their calving grounds in the north.
A journey that gets more challenging every year.
Fences that were designed to keep livestock in
are equally effective at keeping pronghorn out.
[moos loudly]
[horse whinnies, snorts]
[dog barking]
But this is the route their ancestors took,
so they persevere.
[Western music playing]
[moos]
[music intensifies]
Recently, one pronghorn crossed nearly 150 fences...
[snorts]
...on its migration north.
[music becomes rousing]
[music abruptly fades out]
But pronged horns and barbed wire
can be an unhappy combination.
And fences are far from the only problem.
[dramatic Western music playing]
More perilous are the highways that now cut across their path.
[horn blares]
- [brakes shriek] - [music abates]
They may be the fastest land animal in the Americas...
[music reprises]
...but they can't always dodge a car.
[music fades out]
[horn beeps]
The changes brought by the last 200 years
have reduced pronghorn numbers by over 90%.
But there is some good news.
[poignant music playing]
The pronghorn's loyalty to ancestral routes
has made it possible to build overpasses at key crossing points,
and that has almost eliminated road deaths in the area.
As the herd continues north, they reach the real wild west.
Here, they must face not human-made obstacles
but natural ones.
The snow is now melting,
showing that they're on schedule to reach their calving grounds
just in time to give birth there.
[music climaxes]
[music ends]
But the seasonal changes also bring problems.
Ahead lies Wyoming's Gros Ventre River, now swollen with meltwater.
The pronghorn must cross it to get to their breeding grounds,
but they seem nervous.
[apprehensive music playing]
Not about the river itself
but what predators may be hiding on the opposite bank.
[bird shrieks]
In the water,
their speed over land will be of little relevance.
But predators, such as wolves and cougars,
have now been hunted almost to extinction,
so the chances of an attack here are slim.
It's just that the pronghorn don't know that.
It still pays to be cautious.
[music becomes optimistic]
It's got them this far.
Several weeks after setting off,
they, at last, reach their breeding grounds.
The fertile valleys of the Rocky Mountains.
[music climaxes, fades out]
[chorus of insects chirping]
[spiritual music fading in]
Mexico's Baja peninsula
doesn't experience the cold winters of the north.
So the mild temperatures of its seas at this time of the year
make it an excellent seasonal retreat
for one of the world's greatest long-distance travelers.
Gray whales.
It's mid-March,
and six weeks ago, this female gave birth here.
The sheltered waters are warm and free from predators.
It's an excellent nursery.
But such perfection comes at a cost.
There's no food for this mother, and she's been here since December.
So as soon as her calf is strong enough,
she will lead him 8,000 kilometers north
to their feeding grounds in Alaska's Bering Sea.
The longest migration made by any mammal.
Fortunately, her youngster is growing fast.
Nourished by more than 200 liters of milk a day,
the one-ton baby is full of energy.
Luckily, Mother knows just the place for him to let off steam.
[music fades out]
And this is it.
[quirky string music playing]
A shallow sandbar in the middle of the lagoon.
And it's clearly the place to be.
As the tide rolls in over the shallow bank,
it creates a gentle current
attracting whales from across the lagoon.
It's the calf's first introduction to whale society.
And he seems a little shy.
- [bellowing] - Best stay close to Mother.
[calf chirps]
The sandbar is a good place to practice the swimming skills
he'll need for the long journey north.
Jellyfish are carried along with the current,
but he swims against it.
Using it like an underwater treadmill to build up his stamina.
[bellowing]
Every year, over a thousand gray whales migrate to this one lagoon.
But not all are females with calves.
Many are large males that make the long journey here
in the hope of finding a mate.
Females with young are definitely not interested,
though that doesn't put off this amorous male.
And swimming away only seems to encourage him.
Rejection is clearly hard to take
when you've traveled half the length of the planet to get here.
[somber music playing]
And now, he seems to take out his frustration on the calf,
forcing him down, away from the surface.
[music intensifies]
[music abates]
Finally, the male gets the hint.
[ethereal music playing]
It's time for the pair to head north.
Since arriving three months ago,
the female has lost a third of her body weight.
So now she must begin the long trek back to her feeding grounds.
Her youngster will need luck to complete the journey.
One in three gray whale calves
never reach their destination.
The Earth's tilt drives all migrations.
But even at the equator, where the tilt has little seasonal effect,
there are some animals that are constantly on the move.
[chorus of insects, creatures]
[rapid dramatic music playing]
Army ants.
Every day, each runs the equivalent of a human marathon
in order to collect food.
[music intensifies]
These particular ants specialize in capturing the larvae of other insects.
Workers loaded with their prey
are helped to cross gaps in the leaf litter by others,
forming living bridges.
[music continues]
Trails of pheromones lead them to their temporary headquarters.
A bivouac.
[music abates]
A nest built entirely from the bodies of the ants themselves.
[music trails off]
Hidden behind this living wall
lies the control center of the colony,
the queen and her most recent young.
The whole bivouac has hung here for the last two weeks.
But that is about to change.
[ambient music playing]
Day turns to night,
and a signal ripples through the colony.
A chemical cue coming from deep within the bivouac.
[high-pitched electronic music playing]
The message is clear.
It's time to move.
[rapid hypnotic music playing]
These little insects have large appetites.
And having cleared the surrounding forest of living prey,
they must now move and find new feeding grounds.
Following one of the main foraging trails,
workers transport the newly hatched larvae...
while soldiers guard the edges.
[music abates]
There could be as many as half a million ants in this colony.
[music reprises]
And none will be left behind.
[music speeds up]
The reason they proceed under the cover of darkness
now becomes clear.
[music becomes high-pitched]
The queen herself is on the move.
She's bigger than any other individual.
And for the past two weeks,
she's been laying an egg every minute or so
and, therefore, unable to travel.
[music abates]
Now, with her reproductive duties temporarily suspended,
she's able to move to fresh hunting grounds.
This is the only time she's ever visible out in the open.
And the queen is not the army's only important traveler.
In a rare event that only happens every few years,
supersized larvae appear, carried by the workers.
[lively hypnotic music playing]
These are the young males and future queens
who will soon leave this colony and establish their own dynasties.
[music intensifies]
Before daylight returns, the army makes camp.
They will continue to travel every night until they reach fresh hunting grounds.
By then, the queen will be ready to lay more eggs
and add more workers to her empire.
[music trails off]
[ambient music playing]
Back in the north,
the mother gray whale and her calf
are now four weeks into their epic migration.
Since leaving, the youngster has put on over a thousand kilos,
but his mother hasn't eaten for months.
And there is still a lot of ocean to cover
before she can begin her banquet in the Bering Sea.
[vocalizing]
They keep close to the coast, using visual cues to guide them.
She's made this journey many times during the last 30 years,
and a lot has changed since her first trip.
Still, she doesn't shy away from human attention.
[men shouting]
And the calf appears to positively relish the limelight.
[music trails off]
The crowded Californian coast seems a million miles
from their sheltered bay in Mexico.
And it's only going to get busier from here on.
Soon, the pair reach the port of Los Angeles,
the biggest in North America.
[engine chugging]
Nearly 2,000 ships use it every year.
The constant engine noise disrupts the underwater soundscape,
disorientating the whales and increasing the risk of a collision.
[vocalizes]
Scores of whales die every year in ship strikes in these waters.
[music fades out]
[poignant music playing]
This gray whale
was one of the unlucky ones.
Mother and calf have avoided the busiest shipping lanes.
[music becomes ethereal]
But the most dangerous part of the trip lies just ahead.
Monterey Bay.
Thirty-five kilometers of open water.
[music intensifies]
[music becomes apprehensive]
Staying close to the shore here would cost valuable time.
[music becomes menacing]
So she leads her calf across the deep water of the bay.
But it's a risk.
She knows what's out there.
She goes into stealth mode,
stopping her regular contact calls
and surfacing as infrequently as possible.
[music becomes expectant]
[hushed tone] Orca.
Killer whales.
They know these waters well,
and they are on the hunt.
[music becomes dramatic]
[vocalizing]
[music intensifies]
[music abates]
[birds squawking]
Mother and calf have been discovered.
An adult gray weighs ten times as much as an orca
and can be a formidable opponent.
So the pod circle warily, looking for a chance.
[menacing music playing]
They don't want her.
They want her calf.
[unsettling music playing]
[urgent string music playing]
[dramatic music playing]
[music intensifies]
They surge up onto his back and force him underwater,
trying to drown him.
[music becomes somber]
[music gradually getting higher]
[music abates]
Supported by his mother,
he has survived the first attack.
[poignant music playing]
[music abates]
But he's been wounded.
[unsettling music playing]
[music becomes tense]
And now, the pod call in their reinforcements.
A massive five-ton male.
[music intensifies]
[music abates]
Bolstered by this extra muscle,
the orca switch to an all out attack.
There's little the mother can do.
At full ramming speed,
it's like being hit by a bus.
[music climaxes, fades away]
[poignant music playing]
The outcome is inevitable.
This mother will have to continue her journey alone.
[music fades out]
[optimistic music fades in]
For many animals,
the instinct to move is overwhelming,
despite the dangers.
But for every trip that ends in tragedy,
countless millions reach their destination.
[music becomes hypnotic]
Allowing them to reap the rewards of better conditions
and fresh opportunities.
And these migrations are crucial for others too.
[music intensifies]
However, we have now changed the planet.
[music becomes poignant]
Cutting off ancestral routes...
[squeaking]
...and impacting even the most remote corners of the globe.
[chirrups]
But there is hope.
[squawking]
We know more about these journeys than ever before.
[music continues]
And with our help,
many animals are now overcoming the challenges of our modern world.
[music becomes rousing]
For a healthy and connected planet, we must preserve the freedom to move.
And if we do,
the vital journeys of each and every animal
will continue for years to come.
[music intensifies]
[music climaxes, fades out]
[theme tune playing]
[music crescendoes]
[music fades out]