Planet Earth (2006): Season 1, Episode 7 - Great Plains - full transcript
A quarter of the earth's land mass, from arctic to tropical, are open plains consisting of lowland as well as highland plateaus. Here grows virtually indestructible, fast-growing grasses of all sizes that feed the planet's largest herbivore populations, the preys to solitary and social carnivores. Spectacular elements of the seasonal cycle of life can include mass migrations, monsoons, drought and great fires.
Vast open plains.
But any feeling of emptiness is an illusion.
The plains of our planet support
the greatest gatherings of wildlife on Earth.
At the heart of all that happens here
is a single living thing.
This miraculous plant covers
a quarter of all the lands of the Earth.
Grasslands exist wherever there is a little rain,
but not enough to sustain a forest.
Some are huge.
The Central Asian Steppe alone
extends one third of the way around our planet.
and eagles effortlessly cruise the thermals,
scanning the ground beneath for signs of prey.
In the distant reaches of outer Mongolia,
one of the planet's great migrations is underway.
Few people ever see
this extraordinary annual event.
Two million are thought to live here,
but no one really knows.
For much of the time,
they're scattered through this vast landscape,
but once a year they come together
to have their young.
Nearly all will give birth within the next 10 days.
0ut in the open,
communal calving is the safest way to have young.
With so many pairs of eyes keeping watch,
it's almost impossible for predators to sneak up.
There are no bushes, no trees.
There's only one thing to hide behind.
And it's not very effective.
Predators also have a hard time
raising their young on open grassland.
eagles have to nest directly on the ground.
All the inhabitants of the Great Plains
are exposed to the elements.
Fire sparks panic in the herd.
Gazelles are born to run
and even young calves easily outpace the flames,
if they can avoid being trampled.
With nothing to stand in its way,
the blaze consumes anything that can't flee.
Huge quantities of grass, valuable food,
have been lost.
And with it, the old and the weak.
The gazelles move on to new pastures
and leave the desolation behind them.
From the ashes rises the phoenix.
Grass, the incredible survivor.
Because it grows from a protected part
at the base of its stems,
grass is almost indestructible.
Able to repair and reproduce itself rapidly,
it covers more of the Earth's land
than any other plant
and feeds more wildlife than any other.
0ne and a half billion
swarm across the savannahs of Africa.
These are the most numerous birds on Earth.
Some flocks are so vast
that they can take five hours to pass overhead.
0nly grass can feed plagues of these proportions.
The ravenous hordes devour the seeds.
And the leaves and stems are cropped
by great herds of antelope.
The East African savannahs alone
sustain nearly two million wildebeest.
They trim the grass down to its roots,
leaving little in their wake,
but within days the plant will recover
and continue to sustain
the biggest herds on Earth.
Grass is not confined to the tropics.
It manages to grow
even in the bitter conditions of the Arctic.
Beyond the limits of the last tree,
the planet is barren and ice-locked.
A frozen no-man's land at the end of the Earth.
But for a short time each year,
the long, dark winter releases its grip.
and grass that has lain dormant and frozen
throughout the winter sprouts once more.
Green returns to the Arctic.
The receding ice reveals
an immense flat plain the size of Australia.
This is the Arctic tundra.
It's a desolate, silent wilderness.
But it's about to change.
They winter along the Gulf of Mexico,
and in spring they fly
the entire length of North America
to reach the Arctic tundra.
Five million birds make this journey every year.
Their marathon migration
is almost 3,000 miles long
and has taken them three months.
Exhausted and starving,
they touch down inside the Arctic Circle,
back at their traditional breeding grounds at last.
Snow geese pair for life.
As soon as couples arrive,
they must stake a claim to a nesting patch.
Ideal sites are in short supply
and quarrelsome neighbours are all around.
Disputes can be vicious.
It's a long way to travel, but for a short period,
the tundra is the ideal place for a grazer.
The grass grows vigorously
during the short, intense summer
and there are fewer predators than further south.
Here, geese can nest on the ground
in relative safety.
Nonetheless, this female must incubate
her eggs for three weeks
and throughout this time
she will be very vulnerable.
An Arctic fox surveys the colony.
She's been waiting for the geese all winter.
Sneaking up unnoticed is impossible.
Perhaps fortune will favour the bold.
The colony is well-defended.
There are no easy pickings here.
She's driven away from every nest,
but hunger compels her to continue.
There are more eggs here
than she can possibly eat now.
But the nesting season is short.
So she stashes much of her plunder
for later in the year
when all the geese have gone.
other bigger predators prowl the tundra.
For them, finding food on the plains
is an even greater challenge.
Not only is their prey seasonal,
it's also hard to find.
They've been searching for days without a sign.
Somewhere in this immense landscape
there is food for them.
This is it. Caribou.
Travelling 30 miles a day,
they can cover nearly 2,000 miles
during the summer months.
The wolves will starve
if they don't find the caribou.
But it's no easy task to locate prey
that never stops travelling.
Biting flies and the quest for new pasture
drives the migration ever onwards.
A wolf has finally picked up the trail.
The caribou are close.
At last, a chance.
The hunt is on.
The wolf panics the herd,
and the weak and young are singled out.
A calf is separated from its mother.
At the goose colony,
it's high summer and eggs are hatching.
The young all emerge within a day or two,
a marvel of timing.
The colony is now home to a million goslings.
The fox is still gathering all she can get.
Sometimes one mouth simply isn't enough.
0ne will have to do.
Not all food is stored. Some is needed right now.
She has seven hungry cubs to feed.
As their appetites grow, the mother
must work tirelessly to raise her family.
0nly fat, healthy cubs
will survive the Arctic winter.
The vast majority of the goslings
are still flourishing.
Their parents lead them
down to the safety of the water
as soon as they're strong enough
to make the journey.
For the foxes, boom time has come to an end.
But the mother has given her cubs
the best possible start in life.
The geese will continue grazing the tundra
until the summer ends
and they're forced to head south for the winter.
At these latitudes, the sun's rays are weak
and grass can only grow here
for a few months a year.
But further south,
summers are longer and the grasslands flourish.
The prairies of North America.
This rich pasture once supported
the greatest herds ever seen on our planet.
There were once 60 million bison,
but no animal is immune
to intensive hunting by man
or the destruction of its habitat.
And a century ago,
the bison were reduced to barely 1,000.
Now, thanks to rigorous protection,
the species is recovering.
The growing season is long,
and the grass here
can support herds all year round.
Male bison weigh in at one ton.
In high summer,
the bulls are fat from the rich grazing
and in prime condition, but only a few will mate.
Exactly which few is about to be decided.
0n temperate plains around the world,
summer is a time for growth and reproduction.
Now the grass produces its flowers.
New colours also come to the plains.
The northern flowering is mirrored
by the grasslands of the southern hemisphere,
and nowhere is more impressive
than on the veldt of South Africa.
Not all temperate plains
are so rich and colourful in the summer.
This is midsummer on the Tibetan plateau,
the highest great plain in the world.
Despite the conditions, grass survives
and in sufficient quantities
to support the highest of all grazing herds,
those of the wild yak.
Even in summer, life is hard.
Temperatures rarely rise above freezing
and the air is thin.
It's also exceptionally dry for one very big reason,
The great mountain range acts as a barrier,
preventing clouds moving in from the south,
and this casts a giant rain shadow
that leaves Tibet high and dry.
Grass clings to life
even as desiccating winds remove
what little moisture remains in the soil.
So long as grass can survive, so can grazers.
The males are fighting to win territories.
Those that hold the best
are more likely to attract a herd of females.
It's a frisky business.
That counts as a victory,
but he can't assume
the females will actually turn up.
Female asses are mysterious creatures.
They come and go as they please
and much of their behaviour
seems unfathomable to an outsider.
They're the great nomads of the plateau
and will often trek vast distances
across these parched plains
in search of oases.
But when they do find paradise,
they are liable to feed and drink
for just a few hours
and then head back to the dust
for no apparent reason.
Wild ass are the most conspicuous pioneers
of this high frontier,
but the most numerous grazer in Tibet
Pika, a relative of the rabbit.
It, too, feeds on grass.
0n the exposed plateau,
pikas never stray far from their burrows.
But even so, squatters will move in
given half a chance.
While ground peckers and snow finches
can be a nuisance,
they're worth tolerating because they provide
a valuable early warning system.
The bizarre Tibetan fox. The pika's nemesis.
When stalking, it keeps below the skyline,
perhaps helped by its curious body shape.
But why the square head?
In summer, the Tibetan plateau heats up,
drawing in warm, wet air from the south.
But the water never arrives.
As the moist air approaches,
it's forced upwards by the Himalayas
and condenses into huge rain clouds.
These clouds drop all their water
on the southern side of the mountains.
The very peaks that keep Tibet dry
are responsible for the monsoon rains
falling farther south
and the greening of India.
Here, soaked by rain and bathed in tropical sun,
grass reaches its full potential.
Elephant grass is the tallest in the world.
Grass that towers over an elephant
can conceal all sorts of surprises.
The male Lesser Florican.
It's hard work getting noticed
when you go courting in high grass.
The long-grass plains of tropical India
are home to some of the largest
grass-eating mammals on our planet.
And some of the smallest.
Pygmy hogs are no bigger than rabbits.
They're the tiniest and rarest of all wild pigs.
The female is busy collecting grass,
but not for eating.
She's building a nest.
Each piglet may be small enough
to fit in the palm of a hand,
but she does have 10.
This is how grass can grow,
given unlimited sunshine and water.
But on most tropical plains across our planet,
the wet season is followed by a dry one.
0n the African savannahs,
grazers are marching in search of grass and water.
Without rain, these plains can become dust bowls.
Grass can now lose its hold.
Elephants are in immediate danger.
They must drink almost daily.
Driven on by thirst,
they march hundreds of miles
across the parched plains.
Relying on memory,
the matriarchs lead their families
to those special water holes
that saved them in previous years.
This one still has water,
but they must share what remains
with desperately thirsty animals of all kinds.
These are tense times.
The elephants dominate the water hole,
but as night falls the balance of power will shift.
Thirsty herds continue to arrive
throughout the night.
It's a cooler time to travel.
In the darkness, the tables turn.
The elephant's night vision
is little better than our own.
But lions have much more sensitive eyes.
The cats are hungry
and the elephants seem to sense it.
Lions don't usually hunt elephants,
but desperate times require desperate measures.
This herd contains calves, easier targets.
But how to reach them?
The adults encircle their young.
It's an impenetrable wall of grey.
A few exhausted stragglers are still arriving.
0ne of them is alone.
But it's too big for the lions to tackle.
This one looks a little smaller.
A solitary lion stands no chance,
but the whole pride is here.
There are 30 of them
and they are specialist elephant hunters.
This elephant will feed the whole pride
for at least a week.
these drinking holes are dangerous,
but they have no choice.
The dramas that play out here
are a savage reminder
of how important water is
for all life on these plains.
As the dry season finally draws to a close,
Africa's baked savannahs
undergo a radical change.
Rain sweeps across the continent
and grass, the great survivor, rises again.
And the herds return.
For months they've been scattered
over huge areas,
clinging to existence around tiny water holes.
Now, the good times are back.
A few African savannahs are very special.
Here, rainwater from far and wide
flows across the flat plains.
Grass is submerged, but still it grows.
Flooded, burnt, baked and frozen,
grass can withstand it all.
After six months of drought,
grass replaces dust over great areas.
Fresh new shoots draw animals
from great distances.
Many undertake epic migrations
to catch the boom time.
Some resourceful animals live here
all the year round.
Baboons are permanent residents,
but they have to change their behaviour
if they are to gather what they need
on the newly flooded plains.
There's plenty to eat,
but getting to it can be a little uncomfortable.
New water poses problems for the youngsters,
but they know where to find a dry seat.
Ajuicy snail is ample recompense
for sodden paws.
Having survived the dry, barren times,
animals can now reap the rewards.
0n this seasonal planet,
the great plains are lands of feast and famine.
At their peak, they support the greatest
gatherings of wildlife found anywhere on Earth.