Original subtitles

(THEME MUSIC PLAYING)

(BIRDS CHIRPING)

DAVID ATTENBOROUGH: One quarter of all the land on Earth

is covered by a single, remarkable type of plant.

Almost indestructible, it can grow half a metre a day...

...and be tall enough to hide a giant.

(GRUNTING)

That plant is grass,

and the world it creates is truly unique.

The grass in northern India is the tallest on the planet,

home to some of the most impressive creatures to tread the Earth.

(GRUNTS)

(TRUMPETS)

These are the good times,

but in just a few months, all this fresh growth will be gone,

and the animals will be forced to move on.

That is the way things are on grasslands across the planet.

A cycle of abundance, destruction and rebirth

that affects every creature that lives here.

(ELEPHANTS GRUNTING)

The largest grassland on Earth, the vast Eurasian Steppe,

stretches one third of the way around our planet.

Spring rain has brought fresh grass, and with it, new life.

A relic from the Ice Age, a baby Saiga antelope,

just three hours old.

His only company, his twin.

Until they can stand, their mother has left them hidden in the grass.

They should be safe, as long as they remain quiet.

(CALLS)

For these calves, the clock is already ticking.

Their herd will soon be moving on, seeking the freshest new grass.

(CALLS)

Their lanky legs are a sure sign that they're built for a life on the move.

Saiga always give birth to twins,

so their numbers grow rapidly just when grass is plentiful.

Their bizarrely shaped nose can detect fresh growth

from hundreds of kilometres away.

(SAIGAS BLEATING)

The young twins will now begin the nomadic life

they share with most animals on the world's open plains.

(THUNDER RUMBLING)

Grasslands occur where rain is too sporadic for forests to exist.

The rain that a grassland needs to survive for a year

might arrive all at once.

(LIGHTNING CRACKS)

Storms like these can release 30 centimetres of rain in 24 hours.

(HEAVY RAINFALL)

Not much fun if you're out in it.

Eventually the earth can't soak up any more,

(THUNDER CRACKING)

and the grassland undergoes a radical change.

(WATER FLOWING)

Many plants would drown here, but grasses thrive.

They grow so fast,

their leaves quickly rise above the water and into the sunlight.

Here in southern Africa,

water transforms one of the most remarkable grasslands on Earth,

the Okavango.

Every year, 8,000 square kilometres of grassland are flooded.

For one pride of lions, this poses a major problem.

There may be plenty of prey around,

but lions struggle to run it down in water.

The pride has three-month-old cubs. They've never seen water before.

(CUBS MEOWING)

If their mothers don't make a kill soon,

the cubs might not survive the week.

(YOWLS)

But fuelled by the flood, the eruption of grass attracts new possible prey.

Buffalo arrive in herds 2,000 strong.

(GRUNTS)

Powerful, aggressive and united,

they're the most dangerous animal a lion can face.

(BUFFALO GRUNTS)

The biggest bulls don't run.

They're simply too huge to be scared of lions.

At 900 kilos, he weighs more than all five lionesses combined.

The pride do have numbers on their side,

but one sweep of his horns could be deadly.

One distracts the bull up front, while her sisters attack from behind.

The cats must somehow topple the buffalo,

but with swamp under foot, they can't get any traction.

The bull is weakening,

but the lions are tiring, too.

It's now a battle of will as much as strength.

To live, the bull must somehow shake off the lioness.

(DRAMATIC INSTRUMENTAL MUSIC)

The bull is wounded,

but thanks to his thick hide, he will recover.

For the pride, these are hungry times.

(CUB WHIMPERS)

But, ultimately, once the water recedes, there will be new life,

and new food to benefit all.

In the right conditions, grasses have the extraordinary ability

to grow from first shoots to flower in a matter of only days.

Grasses become the miniature equivalents of fruiting trees.

(CRICKET CHIRPS)

And for creatures living within the grass,

this is a landscape as vast and towering as any rainforest.

An excellent place to build a tiny tree house

for a harvest mouse.

(SQUEAKS)

During summer, European meadowlands are full of food,

but only for those that can reach it.

(STEM CRACKS)

Climbing grass is harder than climbing trees,

not least because their stems just won't stay still.

Her prehensile tail acts like a fifth limb,

so she's as agile as a monkey clambering around in a tree.

(STEM CREAKS)

And just as well,

for the best food in this tiny forest is at the very top of its canopy.

Feeding up here, she's exposed.

A barn owl.

Not her finest move...

But it did the trick.

Harvest mice seldom go all the way down to the ground.

It's a tangled and dangerous world down here.

(INSECTS CHITTERING)

But she can read the pattern of the stems overhead like a map,

and so find her way home.

And not a minute too soon.

There are mouths to feed.

(SNIFFS)

Her babies must fatten up quickly.

They need to harvest the summer grasses while they're still rich with food.

On the African savannah, too, seasonal grasses are filled with life,

but it won't last long.

Carmine bee-eaters are superb aerial hunters,

experts at catching insects in midair.

But they have no way of flushing their prey out of the grass.

(INSECTS CHITTERING)

Once alarmed, most insects stay put.

The bee-eaters need someone to stir things up a bit.

(CALLS)

A kori bustard.

It's the world's heaviest flying bird,

so it should be bulky enough to kick up some insects.

(INSECT BUZZING)

Bingo!

Until someone else comes along and cramps your style.

(CHIRPS)

Never mind, perhaps there are bigger opportunities ahead.

What about an ostrich?

The heaviest bird of all.

This time there's more than enough transport to go around.

(SQUAWKING)

Soon, almost every ostrich has its own passenger.

But free riders are only tolerated for so long.

What the bee-eaters really need

is a creature so big it won't even notice them.

(GRUNTING)

Nothing cuts a swathe through grass like an African bull elephant.

The trick is to fly as close to the front of the giant as possible.

They only have a split second to grab the prize.

As more insects are stirred up, the competition intensifies.

(FRENZIED CHIRPING)

With summer drawing to a close, the race to stock up is on.

Soon, the grass will wither, and this opportunity will have gone.

As the dry season takes hold,

food becomes increasingly thin on the ground.

Now, only the most specialised predators on the plains can make a living.

She may be spotted like a cheetah, but this cat is no sprinter.

Instead, she has extra-long legs which give her a high vantage point.

But a serval cat's main weapon are enormous radar ears.

(GRASS RUSTLING)

They help her pinpoint prey hiding in the grass.

But the prey she seeks are canny.

Southern vlei rats.

They know that any sustained movement can give them away.

So they move in short bursts.

(RUSTLING)

But even the slightest rustle will give her a clue.

(RUSTLING)

Warm.

(RUSTLING)

(RUSTLES)

Warmer.

Missed.

(RUSTLING)

(ANIMAL CALLS)

(RUSTLING)

(SQUEAKS)

In better times, she could catch 10 a day,

but now, with so few rodents around, she will have to go hungry.

As drought intensifies, life gets tougher for all.

Predators with permanent territories must tough it out,

while most of their prey disappear over the horizon.

(GRUNTING)

To avoid starvation, many grassland animals follow a nomadic way of life.

Over 2,000,000 wildebeests wander the East African savannahs

chasing the rains.

And they are not alone.

Arriving on the wing,

Jackson's Widowbirds also seek fresh grass.

(CHIRPING)

Although, it's not just food that they're after.

(CHIRPS)

This male wants a mate.

He's grown elaborate breeding plumage for this moment,

but he needs a stage on which to show it off.

By carefully selecting grass blades, each trimmed to the correct length,

he's creating something very special.

He needs an even surface,

and a centre-piece.

The stage is set.

His bachelor pad is sufficiently neat and tidy to attract a female.

The problem is,

can she see it?

(CHIRPS)

He has competition.

(CHIRPING LOUDER)

It might take more than a little gardening to impress the ladies.

Jumping is the right idea,

but he's misjudged the height of the grass.

His rival makes it look easy.

Time to raise his game.

(BOTH CHIRPING)

It's not only who jumps the highest, but who can keep doing so the longest.

Unable to go the distance, his rivals drop out one by one.

Stamina has won him admirers,

now he can show off his courtship arena...

And engage in a little romantic hide-and-seek.

Finally, he's done enough.

The East African savannahs support millions of grazers.

(GRUNTING)

Each year they devour millions of tonnes of grass,

and yet there's one creature here

whose impact is far greater than all these animals combined.

They're found wherever grass grows on the planet,

yet their labours go almost entirely unnoticed.

One of the most remarkable is found here on the grasslands of South America.

These blades are so tough that virtually no large grass eaters can stomach them.

Yet they're harvested on an industrial scale...

(CRACKING)

...by tiny grass cutter ants.

But they themselves can't digest one bit of it.

So, why bother?

The answer is underground,

and it's very ingenious.

Each blade is cut to length and placed into a garden of fungus.

The rotting grass feeds the fungus, and in turn the fungus feeds the ants.

But feeding 5,000,000 workers requires intensive agriculture.

Luckily, they are an industrious lot.

This colony alone will collect over half a tonne of grass every year.

With billions of ant colonies across the world's grasslands

all doing exactly the same thing, that's a mind-boggling amount of grass.

It's estimated that over one third of the grass that grows on Earth

will be harvested by an insect.

In northern Australia, termites memorialise their industry in sculpture.

These astonishing mounds are three metres tall.

They're always built on a north-south axis,

which is why their builders are called compass termites.

These castles of clay

protect their builders from extremes of heat

and seasonal floods experienced on many grasslands.

Termites manage to do what most grass eaters can't,

break down dead grass and extract the nutrients.

But they themselves can be food for those that can reach them.

(SUCKING NOISE)

A half-metre-long tongue

covered in microscopic hooks,

followed by claws longer than those of a velociraptor.

(SNIFFING)

A giant anteater on the plains of South America.

(SLURPING)

It can devour 20,000 insects a day.

Powerful forelegs enable it to rip apart a termite hill with ease.

And as the sun bakes the grass, the termites face new danger.

(FIRE CRACKLES)

In minutes, fire turns grassland to ash.

But the grasses are not dead. Their underground stems are unharmed.

Weeks, months may pass,

but eventually the rains will return and the grass will sprout again.

Some grasslands must endure not only fire, but ice.

As winter approaches, the prairies of North America begin to freeze.

(CRACKING)

(LOW GROWLING)

In summer, bison roamed freely,

almost continuously cropping the abundant green grass.

Now, that grass is not only withered and frozen, it's about to be buried.

Sixty million tonnes of snow now blanket this herd's territory.

(SNORTING)

Pushing through deep snow is exhausting work,

and the bison are now slowly starving.

Just keeping warm saps huge amounts of energy.

(GROWLS)

Their thick coats can insulate them down to minus 30 Celsius.

It's now minus 40.

The only thing that will keep them alive is buried beneath a metre of snow.

And that's a problem shared with a surprising neighbour.

The food the fox seeks is also deep beneath the snow.

(GRUNTING)

The survival of both creatures depends on getting through to the ground.

For the bison, it will be a matter of brute strength.

Massive neck muscles enable them to shovel five tonnes of snow a day.

Their light-weight neighbour needs more precision.

(CHEWING)

The bison have reached their goal,

a mouthful of withered grass.

And where the bison have dug, the fox now spots an opportunity.

Every footstep counts,

but he mustn't break through...

Yet.

He listens carefully to pinpoint his target.

(PATTERING)

It's moving.

(SQUEAKS)

A vole.

Small, but 100 times more nutritious than a mouthful of dried grass.

To get through the winter on these prairies, sometimes brain beats brawn.

Ultimately, life on all grasslands depends on the turn of the seasons.

(CRACKING)

Eight hundred kilometres further north than any tree can survive,

grass returns to life.

Caribou females have journeyed to the far north

to calve.

(CALLS)

Over 70,000 caribou babies will be born in the next few days.

As the calves appear, so too do the leaves of the newly sprouting grass.

And the calves must strengthen quickly.

Within days they will have to keep up with their parents

on a never-ending march.

At one day old, they're already faster than an Olympic sprinter.

They're testing the legs that will carry them thousands of kilometres,

better to learn their limitations now.

(CALLS)

(CARIBOU GRUNTING)

It may look playful, but there's no harder life on the grasslands

than that facing these infants.

The caribou mothers now join together,

each with an infant exactly the same age.

They're setting off on the greatest overland trek made by any animal.

But wherever grass eaters travel, predators lie in wait.

(CARIBOU CALLING)

Here they are, Arctic wolves.

They must seize their chance

while the caribou pass through their territory.

(PANTING)

The wolf runs at the herd, trying to flush out the weak or the slow.

A calf is separated.

At full tilt, 60 kilometres an hour, the wolf is just faster.

But the calf has stamina.

Only a few weeks old, and this calf's will to survive is remarkable.

And it needs to be,

for these young caribou have now started a journey

that will last a lifetime.

Forever chasing the seasonal growth of the grass on which they depend.

Like all grassland creatures, they are at the mercy

of these unpredictable but ultimately bountiful lands.

Grass can survive some of the harshest conditions on Earth,

flood, fire and frost, and still flourish.

So it is that grasslands provide a stage

for the greatest gatherings of wildlife on planet Earth.

Next time,

we venture to the newest habitat on Earth,

our cities.

To reveal the extraordinary ways

that animals survive in this man-made world.

(THEME MUSIC PLAYING)