Training Script Supplement # 2

(additional 30 min)

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A pride of lions,
one of the very few that stands this desert's
scorching temperatures and lack of water.
Hunting here presents special problems.
A herd of antelope, the only prey within fifteen miles.

Out here,
there is no cover for an ambush.
It will have to be a straight chase.
They have failed,
and each failed hunt brings the lions closer to starvation.

To find enough to eat,
the pride continually searches an area the size of Switzerland.
Three days and seventy miles later,
and still, no kill.
These are desperate times.

A dry riverbed on the edge of their territory.
The only animals here are giraffe.
But these one-ton giants could kill a lion with a single kick.
Lions seldom tackle such formidable prey.

But this pride can't go on much longer
- without food.
The whole pride must work together as a team,
if they're to succeed.

Two female lions lead the chase.
Others race to cut off possible escape routes.

The giraffe has the speed and stamina to outrun the pride.
But it's being chased into a trap.
Up ahead, the lead female waits.
It's now up to her.

Most lion hunts end in failure.
But no lions fail more often than those that live in the desert.
Once again, the pride must continue their search.
It does sometimes rain in the desert.

Here in the American West,
storms can strike with devastating force.
After 10 months of drought,
millions of tons of water are dumped on the land in under an hour.

Over millions of years,
sand and gravel carried by the rampaging floods have carved channels through the solid rock.

Salt canyons, hundreds of feet deep.
In some places,
these canyons have widened until the land between them
is sculpted into table lands and isolated peaks,
some of the most dramatic landscapes on the planet.

The rain may be long gone,
but there is water here,
locked away within the tissues of desert plants.

The cactus is unique to American deserts.
They all hoard water,
storing it in swollen stems,
and protecting it behind a barricade of spines.
They're so successful that they dominate these deserts.
But this forest of spikes can cause problems for the animals that live here.

A Harris hawk.
It has developed special techniques for hunting among the cactus.
Ground mice.
Prey.

At the first sign of danger,
they bolt for the safety of the thorns.
But the hawks have a tactic to flush them out.

These are the only birds of prey that hunt in packs.
Flying in formation,
they try to drive their quarry into the open.

But this mouse is staying put.
So now the hawks continue the hunt on foot.

They're closing in from all sides.
Soon, all escape routes are cut off.
The mouse is trapped.
The spines that cover almost every plant in this desert can provide protection and shelter for many animals.

So, why should these spikes be hung with corpses?
What kind of creature could be responsible for creating such a scene?
There's a mysterious killer at work in this desert.
It's a butcher bird.

This little song bird uses the spines as a butcher uses his hook,
to hold its prey as it feeds on it.
And with chicks to feed,
he also uses the spines as a larder.
He's been stocking it for weeks.
Hanging his prey out of the reach of scavengers
on the ground ensures that his newly-hatched young will never go hungry.

A brilliant solution to making the good times last in the desert,
if a little scary.
Some deserts are so arid,
they appear totally devoid of all vegetation.

Yet even these landscapes can be transformed in a matter of days.
These deserts are among the driest in the world.

But just add a little water,
and plants that are dormant for months will burst into life.
And when a desert suddenly turns green,
even the most seemingly desolate can become a land of opportunity.

No creature exploits the greening of a desert more quickly,
or more dramatically,
than a locust.

Madagascar's arid southwest has received its highest rainfall in years.
Now, an army is on the march,
attracted by the smell of newly-sprouting grass.

Locusts are normally solitary creatures,
but when food becomes suddenly plentiful,
they come together into an unstoppable force that devours everything in its path.

But this devastation is about to get a lot worse.

The locusts now transform into winged adults.
And with conditions as good as this,
they do so three times faster than normal.
Now, they are at their most voracious.

And with wings,
they can take to the skies.
Once airborne, the locusts can travel over fifty miles a day
in their search for new feeding grounds.
A super-swarm of this scale may only appear once in a decade.
This one extends over two hundred square miles
and contains several billion individuals.

Between them, they will devour tons of food in a day.
Nothing can strip a land of its vegetation with such speed
as a plague of locusts.
When the food eventually runs out,
the whole army will die.

But not before it's devastated the land.
With no plants to bind them,
thin soils soon turn to dust and blow away.

Now, these barren lands are left to the mercy of the elements.
Scorched by the sun and scoured by windblown sand,
desert rock is shaped into strange,
otherworldly landscapes.

These rocky deserts may have a beguiling beauty,
but when they become this barren,
very little life can endure.

For many animals,
the only way to survive the most hostile times is to keep moving.

In this desert,
brief rains have given way to the dry season.
Food and water are becoming increasingly scarce.
For these zebra,
it's time to leave.

They are setting off on the longest over-land migration
made by any mammal in Africa,
marching towards the scent of distant rains.

As drought intensifies,
desert-living elephants must also undertake long journeys in search of water.
The older females can remember where,
even in times of extreme drought,
there may still be water,
and sometimes lead the herd to a waterhole they may not have visited for decades.

These zebra are almost at the end of their journey.
This is what they've been heading for.
A rare waterhole.

In deserts,
most waterholes are short-lived.
They appear after rains,
but then vanish almost as quickly as they came.

Animals have come here from many miles around.
Yet, this can be a dangerous place in which to linger.
A hundred miles away,
in the heart of the desert,
sandgrouse chicks are hatching.

It's safer for them to be here.
But being so distant from water is a gamble.

With only their mother to shield them from the sun,

if they get nothing to drink,
they will be dead within hours.
Their only hope is their father.
Every morning,
he makes the hundred mile round trip to get water for the family.

Grouse from all over the desert visit this oasis,
arriving together in large flocks.
And that is important.
There's safety in numbers.
The male snatches a drink,
but he also needs to collect water for his chicks.

Using specially-adapted breast feathers,
he can soak up water like a sponge.
But it takes time,
and he is in danger.
A hawk.

Sand birds here are their main prey.
Again and again,
the male sand bird risk their lives in order to collect water for their chicks.

This is why sand birds nest so far from waterholes.
At last,
he's soaked up as much as he can.
Carrying a quarter of his bodyweight in water,
he can now set off on the long journey home.

He's back, and just in time.
He can give the chicks their first-ever drink.
But he will have to undertake this journey
every day for the next two months,
until his chicks can finally make the flight to the waterhole for themselves.

It's July in the deserts of Nevada in the western United States.
The hottest time of the year.
Bands of wild horses, mustang,
are converging on one of the last remaining waterholes around.

Now, water not only offers them the chance to drink.
It can also bring power.
If a stallion can control access to water,
he will have secured mating rights to the entire herd.

So stallions try to dominate these pools,
fighting off rivals who venture too close.
A stranger.
He's traveled ten miles to be here because the pools where he's come from have already dried up.

With him come his females.
If he can't provide them with water,
they will leave him for the white stallion who already dominates this pool.

So he will have to fight.
There is everything to lose.
A broken leg or a shattered jaw would mean a slow and painful death.
A missed kick,
and it's all over.

The new arrival has won.
And his prize is more than just a chance to drink.

He has provided for his herd,
and in the process,
stolen his rival's females.
The white stallion's rule is over.

Desert life is not only shaped by the scarcity of water,
but also by the relentless power of the sun.
The highest temperatures on Earth have all been recorded in its deserts.
Changes in the climate mean temperatures here are rising more than the global average.

And as deserts heat up,
they are also expanding.
Every year,
a further hundred thousand miles of grass and farmland
are turning into barren stretches of dust and rock.

In the heat of the day,
surface temperatures can reach a scorching 70 degrees,
far too hot to handle for most.
But not for this shovel-nosed lizard.

Raising its feet off the ground in turn enables each to briefly cool.
But even this dancing desert specialist can't stand the heat for long.
One option is to find shade.

Dune grass, the only vegetation here,
provides virtually none.
But just beneath the surface of the sand,
it is several degrees cooler.
Avoiding the extreme heat imposes a rhythm on desert life.

And many animals here choose the simplest option of all,
staying hidden all day and only venturing out in the cool of the night.

As darkness falls,
animals appear from seemingly nowhere.
And among them, inevitably,
are hunters.

One of the most voracious nocturnal predators is also one of the hardest to see.
This mysterious creature hardly ever appears on the surface of the dunes.

But there are signs on the sand that can give it away.
It lives only here,
where the sand grains are so perfectly dry and polished

that they flow almost like water.
It's no bigger than a Ping-Pong ball.
A golden mole.
It's totally blind,
but there's nothing to see underground anyway.

Instead, it has superb hearing.
Its entire head acts as an amplifier
that picks up vibrations through the sand.

So, to locate prey on the surface of the dune,
it has, paradoxically,
to thrust its face into the dune.

Termites.
Not easy to catch when you're blind.
Far better to go into stealth mode.
Once below the sand,
it can detect the slightest movement,
allowing it to strike
with pinpoint accuracy.

Well, most of the time.
It can travel two-thirds of a mile a night in search of its dinner.

And right now, it has just detected its main course.
Little wonder it's sometimes called:
"the shark of the dunes".
Food can be so scarce in the desert that even at night,
animals can't afford to be choosy about what they eat.

A desert in the Middle East.
This long-eared bat
is on the hunt.

Most bats catch flying insects on the wing.
But there are so few of these in the desert that this bat must do things differently.

It has to hunt on the ground.
But what really sets it apart is what it's hunting.
A scorpion.
The venom of this species is potent enough to kill a human.

Tackling it seems madness for a bat weighing just 15 grams.
In the pitch black,
both predator and prey are effectively blind.
But the scorpion has one advantage,
he can sense the approach of the bat through vibrations in the sand.

He must rely entirely on its hearing.
If the scorpion doesn't move,
it won't know it's there.
The battle is on.

Armed with crushing pincers and a sting loaded with venom,
this scorpion is a dangerous opponent.
A direct strike on the head.

Is it all over?
Not for this bat.
He clearly has some immunity to the venom,
but repeated stings must still be extraordinarily painful.

And if the bat is not to go hungry,
it must catch another three scorpions before sunrise.

Desert animals have developed remarkable strategies
to make the most of the rare opportunities that come their way.

Although some deserts may not see rain for several years,
most will hold a little water in one form or another.

The trick is simply knowing how to reach it.
Dawn in these dunes,
and something magical is happening.

Moist air lying over the neighboring Atlantic is cooled and blown inland,
forming fog banks that shroud the desert in mist.
This precious moisture lies tantalizingly out of reach
at the top of the dunes,
and it won't last long.
It will be burnt off by the sun just hours after it rises.

Darkling beetles race to the top of the dunes to reach the fog before it vanishes.
Some of these dunes are five hundred feet high,
the tallest in the world.
For a beetle no larger than a thumbnail,
this is the equivalent of us climbing a dune twice the height of Everest.

But even more impressive is what it does next.
Standing perfectly still,
facing into the wind,
the beetle does a headstand.
Fog begins to condense on its body.
Microscopic bumps on its wing cases direct the water
to grooves that channel it towards the mouth.

Before returning down the slip face,
it will drink forty percent of its body weight.
This little beetle has learned how to conjure water
out of the air in one of the driest places on Earth.

And it's not alone on the top of the dunes.
Web-footed geckos use a similar trick.
Surely, few animals go to greater lengths to get a drink.

Unfortunately, chameleons know that on foggy mornings,
the beetles coming down the dunes are juicier than those going up.
The diversity of life that thrives in a world almost totally devoid of water is truly remarkable.

Success in the desert depends on an extraordinary variety
of survival strategies that have evolved over millions of years.
But our planet is changing.
The world's deserts are growing bigger, hotter and drier,
and they're doing so faster than ever before.
How life will cope here in the future remains to be seen.

Next time,
we journey to the world's Great Plains.
Where spectacular gatherings of wildlife cope with extreme change.

And surprising creatures survive in unexpected ways.

One quarter of all the land on Earth
is covered by a single, remarkable type of plant.

Almost indestructible,
it can grow a foot a day...
...and be tall enough to hide a giant.
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.

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.

The largest grassland on Earth, in Asia,
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 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.
For these calves,
the clock is already ticking.

Their herd will soon be moving on,
seeking the freshest new grass.
Their lanky legs are a sure sign that they're built for a life on the move.
Antelope 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 miles away.
The young twins will now begin the nomadic life they share with most animals on the world's open plains.

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.
Storms like these can release 12 inches of rain in 24 hours.
Not much fun if you're out in it.
Eventually the earth can't soak up any more,
and the grassland undergoes a radical change.

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.
Every year, four thousand square miles 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.
If their mothers don't make a kill soon,
the cubs might not survive the week.

But fueled by the flood,
the eruption of grass attracts new possible prey.
Buffalo arrive in herds 2,000 strong.

Powerful, aggressive and united,
they're the most dangerous animal a lion can face.
The biggest bulls don't run.

They're simply too huge to be scared of lions.
He weighs more than all five lions 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 lion.

The bull is wounded,
but thanks to his thick hide,
he will recover.
For the pride, these are hungry times.

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.

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.

During summer,
European meadowlands are full of food,
but only for those that can reach it.

Climbing grass is harder than climbing trees,
not least because their stems won't stay still.
Her tail acts like a fifth limb,
so she's as agile as a monkey clambering around in a tree.

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.
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.
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.

Bee-eaters are superb aerial hunters,
experts at catching insects in mid-air.
But they have no way of flushing their prey out of the grass.
Once alarmed, most insects stay put.
The bee-eaters need someone to stir things up a bit.

A large bird.
It's the world's heaviest flying bird,
so it should be bulky enough to kick up some insects.
Bingo!
Until someone else comes along and cramps your style.

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.

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.

Nothing cuts 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.

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 specialized 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 this cat's main weapon are enormous radar ears.

They help her pinpoint prey hiding in the grass.
But the prey she seeks are canny.
Southern rats.
They know that any sustained movement can give them away.

So they move in short bursts.
But even the slightest rustle
will give her a clue.
Warm.
Warmer.
Missed.

In better times,
she could catch 70 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.
To avoid starvation, many grassland animals follow a nomadic way of life.
Millions of antelope wander the East African savannahs chasing the rains.
And they are not alone.

Arriving on the wing,
Jackson's Widowbirds also seek fresh grass.
Although, it's not just food that they're after.
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 center-piece.
The stage is set.

His bachelor pad is sufficiently neat and tidy to attract a female.
The problem is,
can she see it?
He has competition.

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.
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 plains support millions of grazers.
Each year they devour millions of tons 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 labors 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...
...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 smart.
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 five million 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 build their industry in sculpture.
These astonishing mounds are ten feet 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.
A foot-long tongue covered in microscopic hooks,
followed by claws longer than those of a velociraptor.

A giant anteater on the plains of South America.
It can devour twenty thousand 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.

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.
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 tons of snow now blanket this herd's territory.

Pushing through deep snow is exhausting work,
and the bison are now slowly starving,
just keeping warm saps huge amounts of energy.

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 feet of snow.

And that's a problem shared with a surprising neighbor.
The food the fox seeks is also deep beneath the snow.
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 tons of snow a day.

Their light-weight neighbor needs more precision.
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.
It's moving.
A vole.
Small, but 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.
Eight hundred miles further north than any tree can survive,
grass returns to life.

Caribou females have journeyed to the far north to calve.
Thousands of caribou babies will be born in the next few days.
As the calves appear, so 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 miles,
better to learn their limitations now.

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.

Here they are, Arctic wolves.
They must seize their chance
while the caribou pass through their territory.
The wolf runs at the herd, trying to flush out the weak or the slow.
A calf is separated.

At full tilt, thirty miles 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.

In the last 6,000 years
the surface of our planet has undergone a sudden change.

A new habitat has appeared,
entirely designed and constructed by one species for its own purpose.
This man-made landscape may seem alien to animal life but for the bold,
this is a world of surprising opportunity.

India.
A gang of bachelor male monkeys has come to challenge the resident alpha male.
This alpha rules over a valuable urban territory.
But maintaining dominance here is a constant struggle.
The bachelors have united to try and overthrow him.

If they win,
one of the challengers will take over the alpha's troop of females,
and may kill his infants.
There are 15 males in this bachelor group.

The alpha must evict every single one of them from his territory.
He has chased half the bachelors away,
but a splinter group has looped back and is harassing his females.
Once again, he has to battle.

Finally, he manages to expel them all.
He returns home victorious,
but with a serious wound on his right leg.
It's a hard life for him in the city.
Keeping the intruders away is a daily challenge.

But it's worth it.
For these urban territories are probably the best territories in the world.
They're filled with rich feeding grounds.

Here in the temple gardens,
the monkeys have, over centuries,
developed a surprising relationship.
One that guarantees them a constantly replenished source of food.

The people here associate monkeys with a Hindu God,
and revere them.
They're given all the food they can eat.

And this high-energy diet has led to a baby boom.
Female monkeys in this city give birth to twice as many young as their forest counterparts.
This mother is so well fed that her rich milk can support
something rarely seen in the wild.
Twins.

And all these babies can create troops that are far larger
than those found in the forests nearby.
With less time spent looking for food,
there is more time for play.
The rewards of living in a city can be huge.
The challenge is to find your niche.
But how to create a home in a world that wasn't designed for wildlife?
It's far brighter, louder and busier than anywhere in the natural world.

The continuous traffic creates barriers to animal movement.
And in this decade,
the urban environment is predicted to grow by nearly thirty percent.

What's more, to come here,
animals have to compete with the world's top predator.
People makes the rules here.

Four billion human beings now live in the urban environment.

It's here that animals have to contend with the greatest change
that is happening to the face our planet.
So why would any animal want to come here?

New York City.
This densely built-up landscape is as unnatural as anywhere on Earth.
And yet, this wild falcon looks out onto an ideal habitat.
Strange as it may seem,
this vastly-altered landscape replicates the conditions in which they evolved.

The towering buildings have a multitude of ledges on which falcons can nest,
and the high perches that they need to catch the wind.

New York City has the highest density of nesting falcons anywhere on the planet.
Winds striking the sides of the skyscrapers are deflected upwards
and can help the birds gain height.

And the great areas of concrete roasting in the sun create thermals,
so that, with very little effort,
the birds can soar over the city.

And so many falcons can live here,
because down at street level,
there is a lot of potential prey.
Diving from height,
the falcons can reach speeds of over two hundred miles an hour.
But their prey stay down low and close to the buildings.

Too risky.
The falcon pulls out of his stoop.
But the effort is not wasted.
The falcons need to flush their prey into the open.

And Manhattan is surrounded by water.
Out here the odds change.

With abundant prey here all year round,
it has taken only 40 years for these falcons to establish themselves here.
And now, among skyscrapers,
they're more successful than their cousins living in the wilderness.

Mumbai, in India,
is home to over 20 million people.
And there are predators here that,
though rarely seen,
are rightly feared.
Carnivores, lured by the prospect of plentiful unsuspecting prey are on the prowl.

A leopard.
Every night, under the cover of darkness they come out to hunt.
These are big animals,
and they're looking for large prey to satisfy their hunger.

To catch more than a glimpse of them and reveal their hunting behavior,
you need night-vision cameras.
Leopards have attacked almost 200 people here in the last 25 years.
But humans are not their usual prey.
These leopards are on the hunt for something else.

Pigs.
These leopards prefer to hunt the domestic animals that people have brought to the city in considerable numbers.
The pigs keep their family close.

The ceaseless noise of the city plays to their advantage.
It conceals their approach.
And the leopards are using this cover to hunt all over the city.
This is a thriving population.

In fact, the highest concentration of leopards in the world is right here.
It's not only the abundance of food that attracts wild animals to cities.
They're usually several degrees warmer than the surrounding countryside.

And here in Rome, in December,
one animal is taking full advantage of this extra heat.
And it's leaving its mark.
In a single winter's day,
ten tons of its droppings rain down on the city.

Starlings.
In the evening, they come back to the warmth of the city after feeding
in the neighboring countryside.
They must return to their roosting trees.
But the first to do so are at the highest risk of being caught by birds of prey.

So, they wait for others to arrive.
There's safety in numbers.
As daylight fades, the sky fills with a staggering one million starlings.

And then follows one of nature's great spectaculars.
How, or indeed why, they perform these marvelous aerobatics,
we still do not fully understand.

Eventually, en masse,
they brave the descent and fill the branches of their favorite trees.

On these cold winter nights,
the city's extra warmth can mean the difference between life and death.

A city, of course, can provide not only shelter and abundant food, but glamour.
These varied objects have been carefully chosen
by a bird for their brightness and their color.
This great bowerbird has spent over a decade
building this collection of mostly man-made objects.

Out on a golf course in Townsville, Australia,
he's putting the final touches to his enormous bower,
that he hopes will impress a visiting female.