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[somber cymbal crash]
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[David Attenborough] In 2021,
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the world watched as a family
of wild Chinese elephants slept,
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exhausted after an epic
400-kilometer journey.
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[poignant music playing]
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Forced from their ancestral forests
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by the worst drought on record,
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the family had gone in search
of a new home.
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[music becomes hypnotic]
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Having traveled
through huge swathes of farmland,
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there was still no sign of them stopping.
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But what they did next surprised everyone.
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[music climaxes, fades out]
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Crossing under a five-lane highway,
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the family approached the city of Kunming.
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[elephant growls]
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[siren in distance]
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[dog barking]
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Within days,
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the elephants had reached the city limits.
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[elephant roars]
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[sirens wailing]
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And they quickly found themselves
in a frightening new world.
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[elephant trumpets]
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[horn honking]
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[siren wails]
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[elephant roars]
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[elephant growls]
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Scared and disorientated,
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the family had no choice
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but to turn around
and begin the long march home.
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[poignant music playing]
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Remarkably, despite the damage
they caused,
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the elephants were not just tolerated
by the local people
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but helped,
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with hundreds of thousands of dollars
spent guiding them safely home.
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After almost two years
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and more than a thousand kilometers
on the road,
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the weary caravan
arrived back in the southern forests,
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where the drought had eased.
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Against all odds,
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this part of the family's story
had a happy ending.
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But it showed that when animals are faced
with dramatic change,
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the urge to move away can be overwhelming.
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[music climaxes]
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[music fades out]
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[theme tune playing]
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[music fades out]
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[optimistic music fades in]
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Our planet,
traveling around the sun, is tilted.
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And in January,
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this means it's summer
at the southern end.
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Though, at the bottom of the world,
that isn't always obvious.
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[music fades out]
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[lively string music playing]
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Even in the summer's peak,
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temperatures in Antarctica
barely rise above freezing.
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But with 24-hour daylight,
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there's now just enough warmth
to melt the sea ice around the continent.
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[music climaxes]
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[music becomes livelier]
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And that is important for gentoo penguins,
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who need to reach land in order to breed.
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[music intensifies]
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For the last few weeks,
their lives have been driven
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by a 30-kilometer daily commute
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to their feeding grounds out at sea.
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Now, with bellies full,
they're heading back to their chicks.
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[quacks, trills]
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[quacking, trilling]
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[chirping]
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[chirps softly]
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After a day in the water,
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it takes a while
to get their land legs back.
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- [quirky music playing]
- [squawks]
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[cheeps]
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[squawks]
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Gentoos need rocks free of ice
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on which to lay their eggs
and raise their young.
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So the home straight
is often an uphill waddle
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to the windblown clifftops.
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[music abates]
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[twittering]
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Their chicks hatched eight weeks ago
and are now nearly fully grown.
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In Antarctica's short summer window,
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they're right on target
to fledge before winter returns.
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[quirky music playing]
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The chubbier the chick,
the greater their demand for food.
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[chicks cheeping]
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And some parents
seem reluctant to indulge them.
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- [music accelerates]
- [chirruping]
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But there is value in this behavior.
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By making the chicks work for their meal,
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the adults are able
to assess their strength...
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[incoming chick caws loudly]
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...their stamina,
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and their coordination.
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[chick 1 chirps]
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[chick 2 chirps]
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[music intensifies]
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The prospect of food
entices the chicks down to the water.
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[music stops]
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Though not quite into it.
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It seems that even for a penguin,
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the first step into cold water requires
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a little courage.
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[quacks softly]
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[optimistic music playing]
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But it just takes one to lead
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for others to follow.
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Shallow, sheltered pools are a safe way
of testing their waterproof coats.
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[quacking]
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And with summers so short here,
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they'll need them very soon.
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[wind howling]
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Before long,
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the seas around Antarctica
will be covered by ice once more.
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[ethereal music playing]
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So the young chicks must head
for open water now if they are to feed.
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But they're nervous.
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[caws]
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And for good reason.
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[music becomes menacing]
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Who wants to share the water
with a three-meter leopard seal?
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[squawking softly]
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[snorts]
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And not just one of them.
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But three.
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[warbling]
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Like their namesake,
they hunt by ambushing their prey.
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And gentoo chicks make easy targets.
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[squawks]
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But regardless of the danger,
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the penguins' need to feed is great.
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[frantic string music playing]
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Gentoos are the world's fastest penguins.
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[music becomes sweeping]
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[music becomes dramatic]
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If they can avoid being ambushed,
they have a chance.
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The young penguins
stick together for safety.
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[music abates]
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But in the confusion,
a chick becomes separated.
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It's now one-on-one.
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[music reprises]
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[music intensifies]
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[music intensifies]
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[music intensifies]
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[music abates]
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The penguin's only hope
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is to rely on its great agility
and stamina.
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So the longer the chase,
the better its chances.
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[music reprises]
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[music climaxes]
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[music rapidly fades out]
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[gentle classical music fades in]
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This very lucky young penguin
can now join the others.
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And the open ocean awaits.
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[music fades out]
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[ambient music playing]
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[music fades out]
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[insects chirping]
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In February,
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the northern end of the planet
points away from the sun.
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- [hypnotic music playing]
- [star whooshes]
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[star whooshes]
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So in the Arctic midwinter,
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darkness is almost continuous,
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with the only light
coming from the aurora.
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[music becomes spiritual]
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These ethereal displays are created
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as electrically charged particles
from the sun
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collide with the Earth's magnetic field.
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This is the time when countless animals
begin their long journeys
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to these northern regions.
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[music fades out]
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[chirping]
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Five thousand kilometers to the south,
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snow geese have just started
their annual migration.
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[optimistic music playing]
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[quacking]
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Led by the older, experienced adults,
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they follow the thaw
as it spreads northwards.
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And fly from the Gulf of Mexico
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to their breeding grounds in the Arctic.
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They will reach the tundra
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just as the long days of summer
create the perfect conditions
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in which to raise their chicks.
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[music intensifies]
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They use natural landmarks,
like lakes and rivers,
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to prevent them straying off course.
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But today,
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the world beneath them is very different
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from the one over which
their ancestors flew.
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Where there was once endless savanna,
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there's now industrial farmland.
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[chorus of squawking]
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[music ends]
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But that is not necessarily a bad thing
for the geese.
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To reach the Arctic,
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the flocks need to refuel regularly
along the way,
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so the fields
of America's breadbasket country
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have become vital pit stops.
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[hypnotic music playing]
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This near-endless supply of food
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has meant that the snow geese population
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has doubled in the last 50 years.
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But there's a cost to becoming
one of the world's most numerous goose.
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[squawking]
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[squawking stops]
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Not everything in this modern world
is as it seems.
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- [tense music playing]
- [metallic ticking]
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[squawking]
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[music intensifies]
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- [gunshot]
- [music fades out]
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A quarter of a million are shot each year.
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[stillness]
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[jaunty music fades in]
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Snow geese have to run the gauntlet
of hunters along much of their route.
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00:14:51,265 --> 00:14:55,728
But sandwiched between
two of America's migratory flyways
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lies a patch of wetland,
where they're protected.
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[music intensifies]
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Missouri's Loess Bluffs.
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It's one of the most important
stop-off points
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on their long journey north.
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[chorus of squawking]
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How long they will stay
depends on the weather.
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In February, icy winds blowing down
from the Arctic
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can cause temperatures to suddenly fall.
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And if it's freezing here,
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conditions will be far worse
where they're headed.
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So, for now,
all flights north are suspended.
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[quirky music playing]
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They may be snow geese,
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00:16:01,293 --> 00:16:04,254
but they don't seem to be
at home on the ice.
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[falling goose squawks]
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With the lake's margins frozen,
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the birds become concentrated
in the center.
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The busier it gets,
the less room there is for maneuver.
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[chorus of chirping]
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00:16:28,487 --> 00:16:30,739
And that suits another visitor.
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[menacing music playing]
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Bald eagles come here...
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[screeching]
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...from across North America.
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00:16:45,629 --> 00:16:50,384
And they time their arrival
to coincide with that of the snow geese.
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[music becomes unsettling]
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[jarring violins playing]
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[honks]
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[violins become more frantic]
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[music becomes dramatic]
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00:17:06,316 --> 00:17:09,570
The geese are far too big
to be snatched on the wing,
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00:17:09,653 --> 00:17:12,656
so the eagles use
a different hunting strategy.
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00:17:16,285 --> 00:17:19,955
Flying at the flock,
they scare the birds into the air.
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The tighter the geese are packed,
the better it is for the eagles.
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00:17:31,133 --> 00:17:32,551
[music intensifies]
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00:17:44,938 --> 00:17:48,067
In their panic,
geese collide with one another,
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and limbs are broken.
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00:17:52,988 --> 00:17:55,949
Injured birds are left high and dry
on the ice
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or unable to escape underwater.
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00:17:59,703 --> 00:18:00,704
[music stops]
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00:18:04,792 --> 00:18:05,834
[eagles squawk]
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00:18:06,460 --> 00:18:11,757
All will remain vulnerable
for as long as this cold snap lasts,
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00:18:12,591 --> 00:18:16,887
their onward migration
still blocked by ice and snow.
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00:18:22,810 --> 00:18:24,645
[ambient music fades in]
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00:18:26,063 --> 00:18:30,234
Back in the Arctic,
the sun is slowly beginning to strengthen.
266
00:18:32,361 --> 00:18:33,737
But in late February,
267
00:18:33,821 --> 00:18:36,824
its rays still barely show
above the horizon.
268
00:18:39,034 --> 00:18:42,162
In such frigid conditions,
there's little to eat,
269
00:18:42,246 --> 00:18:44,957
and most animals retreat southwards
270
00:18:45,040 --> 00:18:46,959
or shut down altogether.
271
00:18:54,007 --> 00:18:56,260
But this one does neither.
272
00:18:57,886 --> 00:19:01,807
A lynx, the most northerly cat
in the world.
273
00:19:03,559 --> 00:19:05,394
[music becomes ethereal]
274
00:19:08,647 --> 00:19:12,568
It's well protected from the cold,
so it doesn't retreat.
275
00:19:15,654 --> 00:19:20,033
But it may have to travel
huge distances to find food.
276
00:19:23,829 --> 00:19:25,664
[music becomes hypnotic]
277
00:19:28,125 --> 00:19:30,002
One was even recorded
278
00:19:30,085 --> 00:19:33,881
walking more than 3,000 kilometers
in just one year,
279
00:19:35,382 --> 00:19:37,593
further than anyone thought possible.
280
00:19:47,311 --> 00:19:52,649
This cat relies almost entirely
on just one kind of prey.
281
00:19:54,401 --> 00:19:58,030
And right now, there are very few around.
282
00:19:59,406 --> 00:20:00,866
[sinister music playing]
283
00:20:02,367 --> 00:20:04,119
Snowshoe hares.
284
00:20:09,583 --> 00:20:12,461
Spotting one is only half the challenge.
285
00:20:13,837 --> 00:20:15,631
[music becomes dramatic]
286
00:20:26,767 --> 00:20:28,018
[music fades out]
287
00:20:28,101 --> 00:20:29,311
[purring]
288
00:20:31,271 --> 00:20:33,190
[soft whimsical music playing]
289
00:20:35,692 --> 00:20:36,526
[purrs]
290
00:20:36,610 --> 00:20:39,988
Lynx need to eat every few days,
291
00:20:40,072 --> 00:20:42,074
so his search never ends.
292
00:20:56,129 --> 00:20:57,214
He's in luck.
293
00:20:57,297 --> 00:20:58,297
[sniffs]
294
00:20:58,340 --> 00:21:00,801
He has detected another scent.
295
00:21:00,884 --> 00:21:02,386
[music becomes tense]
296
00:21:10,560 --> 00:21:12,646
[in hushed tone] The hare holds its nerve
297
00:21:14,439 --> 00:21:16,733
and trusts its camouflage.
298
00:21:20,320 --> 00:21:23,573
The lynx can't outpace his prey
over a long run,
299
00:21:23,657 --> 00:21:25,742
so he needs to get close.
300
00:21:41,717 --> 00:21:44,052
[music becomes dramatic]
301
00:21:44,136 --> 00:21:45,429
[music climaxes]
302
00:21:45,512 --> 00:21:47,097
[music ends]
303
00:21:47,180 --> 00:21:49,182
A meal at last.
304
00:21:53,478 --> 00:21:55,230
[ambient music playing]
305
00:21:58,984 --> 00:22:00,902
[music becomes optimistic]
306
00:22:00,986 --> 00:22:04,448
As the Earth's Northern Hemisphere
tilts back towards the sun,
307
00:22:04,531 --> 00:22:07,117
bringing the longer days of March,
308
00:22:07,617 --> 00:22:11,413
pronghorn antelope
start their annual migration.
309
00:22:16,918 --> 00:22:20,964
Their journey will take them
from the snowy plains of southern Wyoming
310
00:22:21,048 --> 00:22:24,468
to the lush valleys
of the Rocky Mountains,
311
00:22:24,551 --> 00:22:26,178
where they will give birth.
312
00:22:27,888 --> 00:22:29,181
[music fades out]
313
00:22:30,432 --> 00:22:31,600
[snorting]
314
00:22:34,353 --> 00:22:38,440
But today, their path has changed
beyond recognition.
315
00:22:40,150 --> 00:22:44,571
And to start with, they have to find a way
through oil and gas fields.
316
00:22:46,365 --> 00:22:47,866
[sprightly music playing]
317
00:22:47,949 --> 00:22:49,785
A male tries his luck.
318
00:22:53,663 --> 00:22:55,040
[music intensifies]
319
00:23:03,882 --> 00:23:04,925
[music abates]
320
00:23:05,717 --> 00:23:06,718
[snorts]
321
00:23:06,802 --> 00:23:09,012
Pronghorn are cautious,
322
00:23:09,763 --> 00:23:12,474
especially when encountering humans.
323
00:23:14,434 --> 00:23:16,937
[woman speaking over two-way radio]
324
00:23:21,608 --> 00:23:23,610
[pipe clanking softly]
325
00:23:27,864 --> 00:23:29,991
[tense music playing]
326
00:23:30,617 --> 00:23:32,411
[in hushed tone] So far, so good.
327
00:23:33,537 --> 00:23:35,747
Now for the rest of the herd.
328
00:23:39,292 --> 00:23:40,292
And...
329
00:23:41,002 --> 00:23:42,002
go!
330
00:23:42,337 --> 00:23:43,880
[dramatic music playing]
331
00:23:52,931 --> 00:23:54,307
[music fades out abruptly]
332
00:23:55,642 --> 00:23:57,394
Over the next couple of months,
333
00:23:57,477 --> 00:23:59,438
they will travel 200 kilometers
334
00:23:59,521 --> 00:24:02,190
to reach their calving grounds
in the north.
335
00:24:03,316 --> 00:24:07,028
A journey that gets
more challenging every year.
336
00:24:11,116 --> 00:24:14,119
Fences that were designed
to keep livestock in
337
00:24:14,202 --> 00:24:18,206
are equally effective
at keeping pronghorn out.
338
00:24:18,290 --> 00:24:19,958
[moos loudly]
339
00:24:21,626 --> 00:24:23,753
[horse whinnies, snorts]
340
00:24:28,508 --> 00:24:30,177
[dog barking]
341
00:24:33,472 --> 00:24:36,183
But this is the route
their ancestors took,
342
00:24:37,017 --> 00:24:38,477
so they persevere.
343
00:24:38,560 --> 00:24:40,312
[Western music playing]
344
00:24:41,855 --> 00:24:42,855
[moos]
345
00:24:45,984 --> 00:24:47,360
[music intensifies]
346
00:24:52,741 --> 00:24:57,621
Recently, one pronghorn
crossed nearly 150 fences...
347
00:24:57,704 --> 00:24:58,580
[snorts]
348
00:24:58,663 --> 00:25:00,373
...on its migration north.
349
00:25:02,417 --> 00:25:04,336
[music becomes rousing]
350
00:25:08,298 --> 00:25:09,674
[music abruptly fades out]
351
00:25:09,758 --> 00:25:12,761
But pronged horns and barbed wire
352
00:25:14,095 --> 00:25:16,723
can be an unhappy combination.
353
00:25:22,020 --> 00:25:25,232
And fences are far from the only problem.
354
00:25:25,315 --> 00:25:26,942
[dramatic Western music playing]
355
00:25:30,237 --> 00:25:34,324
More perilous are the highways
that now cut across their path.
356
00:25:39,454 --> 00:25:40,956
[horn blares]
357
00:25:49,047 --> 00:25:50,924
- [brakes shriek]
- [music abates]
358
00:25:51,007 --> 00:25:54,469
They may be the fastest land animal
in the Americas...
359
00:25:55,303 --> 00:25:56,513
[music reprises]
360
00:25:58,473 --> 00:26:00,767
...but they can't always dodge a car.
361
00:26:03,478 --> 00:26:04,354
[music fades out]
362
00:26:04,437 --> 00:26:05,730
[horn beeps]
363
00:26:05,814 --> 00:26:08,650
The changes brought by the last 200 years
364
00:26:09,192 --> 00:26:13,405
have reduced pronghorn numbers
by over 90%.
365
00:26:16,199 --> 00:26:18,577
But there is some good news.
366
00:26:18,660 --> 00:26:20,829
[poignant music playing]
367
00:26:22,497 --> 00:26:25,333
The pronghorn's loyalty
to ancestral routes
368
00:26:25,417 --> 00:26:30,046
has made it possible to build overpasses
at key crossing points,
369
00:26:30,714 --> 00:26:34,426
and that has almost eliminated
road deaths in the area.
370
00:26:39,222 --> 00:26:44,019
As the herd continues north,
they reach the real wild west.
371
00:26:46,730 --> 00:26:50,483
Here, they must face
not human-made obstacles
372
00:26:50,567 --> 00:26:52,068
but natural ones.
373
00:27:04,956 --> 00:27:07,083
The snow is now melting,
374
00:27:07,167 --> 00:27:10,629
showing that they're on schedule
to reach their calving grounds
375
00:27:10,712 --> 00:27:13,381
just in time to give birth there.
376
00:27:19,763 --> 00:27:20,889
[music climaxes]
377
00:27:20,972 --> 00:27:21,973
[music ends]
378
00:27:22,057 --> 00:27:25,185
But the seasonal changes
also bring problems.
379
00:27:25,935 --> 00:27:31,066
Ahead lies Wyoming's Gros Ventre River,
now swollen with meltwater.
380
00:27:33,401 --> 00:27:36,696
The pronghorn must cross it
to get to their breeding grounds,
381
00:27:36,780 --> 00:27:38,948
but they seem nervous.
382
00:27:39,032 --> 00:27:40,617
[apprehensive music playing]
383
00:27:40,700 --> 00:27:43,244
Not about the river itself
384
00:27:43,328 --> 00:27:46,581
but what predators
may be hiding on the opposite bank.
385
00:27:47,165 --> 00:27:48,416
[bird shrieks]
386
00:28:04,224 --> 00:28:05,225
In the water,
387
00:28:05,809 --> 00:28:09,562
their speed over land
will be of little relevance.
388
00:28:14,901 --> 00:28:17,696
But predators, such as wolves and cougars,
389
00:28:17,779 --> 00:28:20,615
have now been hunted almost to extinction,
390
00:28:20,699 --> 00:28:23,410
so the chances of an attack here are slim.
391
00:28:26,204 --> 00:28:28,915
It's just that
the pronghorn don't know that.
392
00:28:33,920 --> 00:28:36,089
It still pays to be cautious.
393
00:28:37,215 --> 00:28:39,175
[music becomes optimistic]
394
00:28:39,259 --> 00:28:40,677
It's got them this far.
395
00:28:51,730 --> 00:28:53,815
Several weeks after setting off,
396
00:28:54,315 --> 00:28:57,569
they, at last,
reach their breeding grounds.
397
00:28:58,069 --> 00:29:00,947
The fertile valleys
of the Rocky Mountains.
398
00:29:01,698 --> 00:29:03,992
[music climaxes, fades out]
399
00:29:04,075 --> 00:29:06,119
[chorus of insects chirping]
400
00:29:06,202 --> 00:29:08,246
[spiritual music fading in]
401
00:29:08,830 --> 00:29:11,249
Mexico's Baja peninsula
402
00:29:11,332 --> 00:29:14,502
doesn't experience the cold winters
of the north.
403
00:29:16,755 --> 00:29:20,425
So the mild temperatures of its seas
at this time of the year
404
00:29:20,925 --> 00:29:23,595
make it an excellent seasonal retreat
405
00:29:23,678 --> 00:29:27,265
for one of the world's greatest
long-distance travelers.
406
00:29:32,771 --> 00:29:34,522
Gray whales.
407
00:29:40,236 --> 00:29:41,236
It's mid-March,
408
00:29:41,988 --> 00:29:46,242
and six weeks ago,
this female gave birth here.
409
00:29:50,079 --> 00:29:54,000
The sheltered waters
are warm and free from predators.
410
00:29:54,793 --> 00:29:57,003
It's an excellent nursery.
411
00:30:00,381 --> 00:30:03,384
But such perfection comes at a cost.
412
00:30:06,387 --> 00:30:10,975
There's no food for this mother,
and she's been here since December.
413
00:30:14,312 --> 00:30:16,856
So as soon as her calf is strong enough,
414
00:30:16,940 --> 00:30:19,943
she will lead him 8,000 kilometers north
415
00:30:20,026 --> 00:30:23,571
to their feeding grounds
in Alaska's Bering Sea.
416
00:30:25,114 --> 00:30:28,159
The longest migration made by any mammal.
417
00:30:35,583 --> 00:30:38,837
Fortunately, her youngster
is growing fast.
418
00:30:44,717 --> 00:30:47,887
Nourished by more than
200 liters of milk a day,
419
00:30:47,971 --> 00:30:51,099
the one-ton baby is full of energy.
420
00:30:56,729 --> 00:31:01,317
Luckily, Mother knows just the place
for him to let off steam.
421
00:31:01,401 --> 00:31:02,401
[music fades out]
422
00:31:04,320 --> 00:31:05,446
And this is it.
423
00:31:07,031 --> 00:31:09,117
[quirky string music playing]
424
00:31:14,414 --> 00:31:17,834
A shallow sandbar
in the middle of the lagoon.
425
00:31:19,377 --> 00:31:22,463
And it's clearly the place to be.
426
00:31:25,174 --> 00:31:28,094
As the tide rolls in
over the shallow bank,
427
00:31:28,177 --> 00:31:30,346
it creates a gentle current
428
00:31:30,430 --> 00:31:33,600
attracting whales from across the lagoon.
429
00:31:37,478 --> 00:31:40,940
It's the calf's first introduction
to whale society.
430
00:31:41,941 --> 00:31:43,985
And he seems a little shy.
431
00:31:45,653 --> 00:31:48,114
- [bellowing]
- Best stay close to Mother.
432
00:31:51,242 --> 00:31:52,911
[calf chirps]
433
00:31:54,621 --> 00:31:58,249
The sandbar is a good place
to practice the swimming skills
434
00:31:58,333 --> 00:32:00,752
he'll need for the long journey north.
435
00:32:02,795 --> 00:32:05,590
Jellyfish are carried along
with the current,
436
00:32:05,673 --> 00:32:07,926
but he swims against it.
437
00:32:11,179 --> 00:32:15,058
Using it like an underwater treadmill
to build up his stamina.
438
00:32:15,141 --> 00:32:16,643
[bellowing]
439
00:32:24,150 --> 00:32:29,322
Every year, over a thousand gray whales
migrate to this one lagoon.
440
00:32:32,116 --> 00:32:35,078
But not all are females with calves.
441
00:32:38,247 --> 00:32:41,793
Many are large males
that make the long journey here
442
00:32:41,876 --> 00:32:44,087
in the hope of finding a mate.
443
00:32:48,841 --> 00:32:51,761
Females with young
are definitely not interested,
444
00:32:52,470 --> 00:32:55,056
though that doesn't put off
this amorous male.
445
00:33:01,813 --> 00:33:05,483
And swimming away
only seems to encourage him.
446
00:33:15,493 --> 00:33:17,829
Rejection is clearly hard to take
447
00:33:17,912 --> 00:33:21,124
when you've traveled
half the length of the planet to get here.
448
00:33:21,207 --> 00:33:22,792
[somber music playing]
449
00:33:24,544 --> 00:33:28,506
And now, he seems
to take out his frustration on the calf,
450
00:33:28,589 --> 00:33:31,342
forcing him down, away from the surface.
451
00:33:32,010 --> 00:33:33,469
[music intensifies]
452
00:33:39,684 --> 00:33:40,977
[music abates]
453
00:33:41,060 --> 00:33:43,688
Finally, the male gets the hint.
454
00:33:45,231 --> 00:33:47,358
[ethereal music playing]
455
00:33:49,110 --> 00:33:51,863
It's time for the pair to head north.
456
00:33:53,322 --> 00:33:55,199
Since arriving three months ago,
457
00:33:55,283 --> 00:33:58,327
the female has lost
a third of her body weight.
458
00:33:59,746 --> 00:34:03,499
So now she must begin
the long trek back to her feeding grounds.
459
00:34:05,752 --> 00:34:09,047
Her youngster will need luck
to complete the journey.
460
00:34:11,466 --> 00:34:13,926
One in three gray whale calves
461
00:34:14,927 --> 00:34:16,804
never reach their destination.
462
00:34:27,607 --> 00:34:31,402
The Earth's tilt drives all migrations.
463
00:34:31,903 --> 00:34:35,990
But even at the equator,
where the tilt has little seasonal effect,
464
00:34:36,491 --> 00:34:40,745
there are some animals
that are constantly on the move.
465
00:34:40,828 --> 00:34:42,622
[chorus of insects, creatures]
466
00:34:43,289 --> 00:34:45,500
[rapid dramatic music playing]
467
00:34:51,714 --> 00:34:53,049
Army ants.
468
00:34:57,929 --> 00:35:01,974
Every day, each runs the equivalent
of a human marathon
469
00:35:02,058 --> 00:35:03,810
in order to collect food.
470
00:35:04,477 --> 00:35:05,853
[music intensifies]
471
00:35:13,111 --> 00:35:18,491
These particular ants specialize
in capturing the larvae of other insects.
472
00:35:28,000 --> 00:35:29,836
Workers loaded with their prey
473
00:35:29,919 --> 00:35:33,089
are helped to cross gaps
in the leaf litter by others,
474
00:35:33,172 --> 00:35:34,632
forming living bridges.
475
00:35:37,802 --> 00:35:39,095
[music continues]
476
00:35:41,389 --> 00:35:46,811
Trails of pheromones
lead them to their temporary headquarters.
477
00:35:51,899 --> 00:35:52,775
A bivouac.
478
00:35:52,859 --> 00:35:53,693
[music abates]
479
00:35:53,776 --> 00:35:58,531
A nest built entirely
from the bodies of the ants themselves.
480
00:35:59,323 --> 00:36:00,616
[music trails off]
481
00:36:01,909 --> 00:36:03,953
Hidden behind this living wall
482
00:36:04,036 --> 00:36:06,956
lies the control center of the colony,
483
00:36:07,039 --> 00:36:09,667
the queen and her most recent young.
484
00:36:10,877 --> 00:36:14,630
The whole bivouac
has hung here for the last two weeks.
485
00:36:15,131 --> 00:36:17,300
But that is about to change.
486
00:36:19,010 --> 00:36:20,761
[ambient music playing]
487
00:36:31,981 --> 00:36:34,275
Day turns to night,
488
00:36:34,358 --> 00:36:37,278
and a signal ripples through the colony.
489
00:36:40,489 --> 00:36:44,619
A chemical cue
coming from deep within the bivouac.
490
00:36:45,369 --> 00:36:47,371
[high-pitched electronic music playing]
491
00:36:47,455 --> 00:36:48,831
The message is clear.
492
00:36:50,124 --> 00:36:51,876
It's time to move.
493
00:36:51,959 --> 00:36:54,086
[rapid hypnotic music playing]
494
00:36:59,175 --> 00:37:02,011
These little insects have large appetites.
495
00:37:03,429 --> 00:37:06,265
And having cleared the surrounding forest
of living prey,
496
00:37:07,391 --> 00:37:11,187
they must now move
and find new feeding grounds.
497
00:37:16,359 --> 00:37:19,654
Following one of the main foraging trails,
498
00:37:19,737 --> 00:37:22,782
workers transport
the newly hatched larvae...
499
00:37:25,451 --> 00:37:27,703
while soldiers guard the edges.
500
00:37:30,164 --> 00:37:31,415
[music abates]
501
00:37:31,499 --> 00:37:34,710
There could be as many
as half a million ants in this colony.
502
00:37:34,794 --> 00:37:35,920
[music reprises]
503
00:37:36,462 --> 00:37:38,673
And none will be left behind.
504
00:37:41,884 --> 00:37:43,177
[music speeds up]
505
00:37:44,512 --> 00:37:47,056
The reason they proceed
under the cover of darkness
506
00:37:47,139 --> 00:37:48,516
now becomes clear.
507
00:37:49,100 --> 00:37:51,102
[music becomes high-pitched]
508
00:37:54,021 --> 00:37:56,565
The queen herself is on the move.
509
00:37:58,859 --> 00:38:01,737
She's bigger than any other individual.
510
00:38:01,821 --> 00:38:03,406
And for the past two weeks,
511
00:38:03,489 --> 00:38:06,117
she's been laying an egg
every minute or so
512
00:38:06,200 --> 00:38:08,369
and, therefore, unable to travel.
513
00:38:08,452 --> 00:38:09,453
[music abates]
514
00:38:15,293 --> 00:38:18,963
Now, with her reproductive duties
temporarily suspended,
515
00:38:19,046 --> 00:38:22,133
she's able to move
to fresh hunting grounds.
516
00:38:24,093 --> 00:38:28,556
This is the only time she's ever visible
out in the open.
517
00:38:30,808 --> 00:38:34,645
And the queen
is not the army's only important traveler.
518
00:38:37,106 --> 00:38:40,693
In a rare event
that only happens every few years,
519
00:38:41,319 --> 00:38:45,281
supersized larvae appear,
carried by the workers.
520
00:38:47,408 --> 00:38:49,493
[lively hypnotic music playing]
521
00:38:51,329 --> 00:38:54,874
These are the young males
and future queens
522
00:38:54,957 --> 00:38:59,211
who will soon leave this colony
and establish their own dynasties.
523
00:39:06,844 --> 00:39:08,262
[music intensifies]
524
00:39:10,848 --> 00:39:14,685
Before daylight returns,
the army makes camp.
525
00:39:22,360 --> 00:39:27,198
They will continue to travel every night
until they reach fresh hunting grounds.
526
00:39:29,950 --> 00:39:33,662
By then, the queen will be ready
to lay more eggs
527
00:39:33,746 --> 00:39:36,499
and add more workers to her empire.
528
00:39:37,500 --> 00:39:38,500
[music trails off]
529
00:39:39,126 --> 00:39:40,878
[ambient music playing]
530
00:39:45,758 --> 00:39:47,134
Back in the north,
531
00:39:47,218 --> 00:39:49,428
the mother gray whale and her calf
532
00:39:49,512 --> 00:39:52,598
are now four weeks
into their epic migration.
533
00:39:56,477 --> 00:40:00,564
Since leaving, the youngster has put on
over a thousand kilos,
534
00:40:01,440 --> 00:40:04,485
but his mother hasn't eaten for months.
535
00:40:07,655 --> 00:40:09,782
And there is still a lot of ocean to cover
536
00:40:09,865 --> 00:40:13,327
before she can begin
her banquet in the Bering Sea.
537
00:40:15,371 --> 00:40:16,914
[vocalizing]
538
00:40:20,543 --> 00:40:25,423
They keep close to the coast,
using visual cues to guide them.
539
00:40:28,634 --> 00:40:32,179
She's made this journey many times
during the last 30 years,
540
00:40:33,139 --> 00:40:36,225
and a lot has changed
since her first trip.
541
00:40:40,104 --> 00:40:43,607
Still, she doesn't shy away
from human attention.
542
00:40:43,691 --> 00:40:45,025
[men shouting]
543
00:40:49,071 --> 00:40:53,451
And the calf appears
to positively relish the limelight.
544
00:40:57,746 --> 00:40:59,039
[music trails off]
545
00:41:00,332 --> 00:41:04,211
The crowded Californian coast
seems a million miles
546
00:41:04,295 --> 00:41:06,213
from their sheltered bay in Mexico.
547
00:41:07,756 --> 00:41:10,968
And it's only going to get busier
from here on.
548
00:41:17,349 --> 00:41:21,228
Soon, the pair reach
the port of Los Angeles,
549
00:41:21,937 --> 00:41:23,898
the biggest in North America.
550
00:41:31,947 --> 00:41:33,324
[engine chugging]
551
00:41:33,407 --> 00:41:36,619
Nearly 2,000 ships use it every year.
552
00:41:39,955 --> 00:41:44,627
The constant engine noise
disrupts the underwater soundscape,
553
00:41:44,710 --> 00:41:49,298
disorientating the whales
and increasing the risk of a collision.
554
00:41:50,883 --> 00:41:52,092
[vocalizes]
555
00:41:53,344 --> 00:41:58,265
Scores of whales die every year
in ship strikes in these waters.
556
00:41:59,558 --> 00:42:00,809
[music fades out]
557
00:42:01,602 --> 00:42:02,853
[poignant music playing]
558
00:42:02,937 --> 00:42:04,396
This gray whale
559
00:42:04,980 --> 00:42:07,107
was one of the unlucky ones.
560
00:42:13,113 --> 00:42:18,035
Mother and calf have avoided
the busiest shipping lanes.
561
00:42:18,869 --> 00:42:20,579
[music becomes ethereal]
562
00:42:20,663 --> 00:42:24,500
But the most dangerous part of the trip
lies just ahead.
563
00:42:26,877 --> 00:42:28,170
Monterey Bay.
564
00:42:28,712 --> 00:42:31,215
Thirty-five kilometers of open water.
565
00:42:31,298 --> 00:42:32,883
[music intensifies]
566
00:42:32,967 --> 00:42:34,969
[music becomes apprehensive]
567
00:42:39,598 --> 00:42:43,477
Staying close to the shore here
would cost valuable time.
568
00:42:44,520 --> 00:42:45,771
[music becomes menacing]
569
00:42:45,854 --> 00:42:49,650
So she leads her calf
across the deep water of the bay.
570
00:42:51,277 --> 00:42:52,945
But it's a risk.
571
00:42:56,699 --> 00:42:58,701
She knows what's out there.
572
00:43:04,206 --> 00:43:06,750
She goes into stealth mode,
573
00:43:08,127 --> 00:43:10,588
stopping her regular contact calls
574
00:43:10,671 --> 00:43:13,591
and surfacing as infrequently as possible.
575
00:43:15,009 --> 00:43:16,844
[music becomes expectant]
576
00:43:25,060 --> 00:43:26,060
[hushed tone] Orca.
577
00:43:28,522 --> 00:43:29,690
Killer whales.
578
00:43:31,442 --> 00:43:33,152
They know these waters well,
579
00:43:34,153 --> 00:43:36,071
and they are on the hunt.
580
00:43:36,614 --> 00:43:38,449
[music becomes dramatic]
581
00:43:49,710 --> 00:43:51,712
[vocalizing]
582
00:43:59,261 --> 00:44:00,638
[music intensifies]
583
00:44:03,932 --> 00:44:04,975
[music abates]
584
00:44:05,059 --> 00:44:06,393
[birds squawking]
585
00:44:07,478 --> 00:44:10,356
Mother and calf have been discovered.
586
00:44:14,068 --> 00:44:18,030
An adult gray
weighs ten times as much as an orca
587
00:44:18,113 --> 00:44:20,574
and can be a formidable opponent.
588
00:44:22,618 --> 00:44:26,497
So the pod circle warily,
looking for a chance.
589
00:44:26,580 --> 00:44:28,415
[menacing music playing]
590
00:44:32,503 --> 00:44:33,754
They don't want her.
591
00:44:35,422 --> 00:44:37,049
They want her calf.
592
00:44:37,132 --> 00:44:39,051
[unsettling music playing]
593
00:44:39,134 --> 00:44:41,220
[urgent string music playing]
594
00:44:44,556 --> 00:44:46,392
[dramatic music playing]
595
00:44:52,272 --> 00:44:53,774
[music intensifies]
596
00:44:58,654 --> 00:45:02,282
They surge up onto his back
and force him underwater,
597
00:45:02,366 --> 00:45:04,076
trying to drown him.
598
00:45:04,993 --> 00:45:06,578
[music becomes somber]
599
00:45:10,374 --> 00:45:12,376
[music gradually getting higher]
600
00:45:16,046 --> 00:45:17,506
[music abates]
601
00:45:17,589 --> 00:45:19,007
Supported by his mother,
602
00:45:19,091 --> 00:45:21,593
he has survived the first attack.
603
00:45:21,677 --> 00:45:23,470
[poignant music playing]
604
00:45:26,181 --> 00:45:27,266
[music abates]
605
00:45:28,559 --> 00:45:30,310
But he's been wounded.
606
00:45:30,894 --> 00:45:32,271
[unsettling music playing]
607
00:45:32,354 --> 00:45:33,856
[music becomes tense]
608
00:45:34,606 --> 00:45:37,901
And now, the pod
call in their reinforcements.
609
00:45:41,488 --> 00:45:43,991
A massive five-ton male.
610
00:45:54,042 --> 00:45:55,461
[music intensifies]
611
00:45:56,295 --> 00:45:57,337
[music abates]
612
00:46:00,632 --> 00:46:02,718
Bolstered by this extra muscle,
613
00:46:02,801 --> 00:46:05,512
the orca switch to an all out attack.
614
00:46:16,940 --> 00:46:18,817
There's little the mother can do.
615
00:46:21,487 --> 00:46:23,238
At full ramming speed,
616
00:46:24,364 --> 00:46:26,325
it's like being hit by a bus.
617
00:46:26,408 --> 00:46:29,077
[music climaxes, fades away]
618
00:46:31,580 --> 00:46:33,373
[poignant music playing]
619
00:46:37,628 --> 00:46:40,047
The outcome is inevitable.
620
00:46:52,810 --> 00:46:57,105
This mother will have to continue
her journey alone.
621
00:47:05,072 --> 00:47:06,406
[music fades out]
622
00:47:06,490 --> 00:47:08,116
[optimistic music fades in]
623
00:47:08,200 --> 00:47:09,535
For many animals,
624
00:47:10,369 --> 00:47:13,497
the instinct to move is overwhelming,
625
00:47:14,665 --> 00:47:16,416
despite the dangers.
626
00:47:18,710 --> 00:47:20,921
But for every trip that ends in tragedy,
627
00:47:21,713 --> 00:47:24,424
countless millions
reach their destination.
628
00:47:24,508 --> 00:47:26,176
[music becomes hypnotic]
629
00:47:33,559 --> 00:47:36,687
Allowing them to reap the rewards
of better conditions
630
00:47:38,230 --> 00:47:39,898
and fresh opportunities.
631
00:47:42,901 --> 00:47:46,405
And these migrations
are crucial for others too.
632
00:47:46,488 --> 00:47:47,906
[music intensifies]
633
00:47:54,371 --> 00:47:57,541
However, we have now changed the planet.
634
00:47:58,292 --> 00:48:00,043
[music becomes poignant]
635
00:48:02,379 --> 00:48:04,506
Cutting off ancestral routes...
636
00:48:06,508 --> 00:48:07,801
[squeaking]
637
00:48:07,885 --> 00:48:11,805
...and impacting even the most remote
corners of the globe.
638
00:48:13,557 --> 00:48:15,100
[chirrups]
639
00:48:16,560 --> 00:48:17,895
But there is hope.
640
00:48:17,978 --> 00:48:19,187
[squawking]
641
00:48:21,565 --> 00:48:24,776
We know more about these journeys
than ever before.
642
00:48:24,860 --> 00:48:26,111
[music continues]
643
00:48:30,616 --> 00:48:31,783
And with our help,
644
00:48:31,867 --> 00:48:36,496
many animals are now overcoming
the challenges of our modern world.
645
00:48:39,041 --> 00:48:40,208
[music becomes rousing]
646
00:48:40,292 --> 00:48:45,547
For a healthy and connected planet,
we must preserve the freedom to move.
647
00:48:50,260 --> 00:48:51,553
And if we do,
648
00:48:51,637 --> 00:48:54,890
the vital journeys
of each and every animal
649
00:48:54,973 --> 00:48:57,392
will continue for years to come.
650
00:49:07,235 --> 00:49:08,654
[music intensifies]
651
00:49:12,449 --> 00:49:14,451
[music climaxes, fades out]
652
00:49:14,534 --> 00:49:15,994
[theme tune playing]
653
00:50:04,167 --> 00:50:06,169
[music crescendoes]
654
00:50:41,413 --> 00:50:42,706
[music fades out]