It's a universal dream to fly like a bird.
To soar on wings into the heavens.
But it's nothing compared to the reality.
This is our planet seen as never before.
A bird's eye view.
Theirs is a journey that covers the world...
..filled with astonishing natural events...
..extreme challenges...
..and hard-won rewards.
This is the world on the wing.
It's autumn across the northern steppes of Asia
and flocks of demoiselle cranes are heading south for the winter.
It's a race against time,
as they must reach India before winter closes in.
Blocking their path is the Himalayas,
the highest mountain range on Earth.
It's a barrier that extends for 1,500 miles
and, in places, soars five miles high.
Flying over the top isn't an option.
The only way through is a treacherous maze
of valleys and canyons.
Each year, thousands of cranes negotiate a pass
that leads them 200 miles to the other side.
They have a huge challenge ahead of them.
Many will not make it out alive.
Already they face danger - bad weather is closing in.
They gain height to face the challenge,
but they are battling against a headwind.
No matter how hard they try, they make little progress.
It's the last thing they need so early in their journey.
The wind stops them in their tracks, forcing them to fly lower and lower.
On the valley floor, villages nestle in the most sheltered spots.
It's here that the cranes find refuge.
They mustn't hang around for long.
If winter comes early, they won't make it out alive.
These cranes aren't the only ones attempting the journey.
Above are some of nature's most skilled high-fliers.
Five miles above the face of the Earth,
bar-headed geese take on the Himalayas...the hard way.
Here, the temperature plummets to -40 degrees
and the air is so thin most animals would die within minutes.
But these extreme aeronauts take it in their stride.
They could climb to twice this height and still survive.
Their blood can absorb oxygen better than any other bird -
a real help in this rarefied air.
Bar-headed geese cross the vast mountain range in just a few hours.
Ahead lies their winter destination -
the warm lowlands of the Indian subcontinent.
They've spent the summer
on the sparsely inhabited steppes of Siberia.
Now they are heading for the second most populated country on Earth.
The "Blue City" of Jodhpur in Rajasthan
is one of the first landmarks that migrating birds encounter.
Long-legged buzzards are among the early arrivals
and they are desperately in need of a meal.
Compared to the barren steppes,
this landscape of roads and buildings is actually a land of plenty.
The famous Mehrangarh Fort is home to the buzzard's favourite prey.
By gaining height, he can study their movements.
Pigeons love this ancient citadel.
Their ancestors would have nested on cliff faces.
Nowadays, these battlements offer superior accommodation.
But even in the midst of the city,
the pigeons can't escape their natural predators.
The buzzard dives at the masses.
The pigeons take evasive action, falling like leaves.
A single bird makes a far easier target.
But he drops out of reach.
The fort's defences provide vital bolt-holes.
But he's not called the long-legged buzzard for nothing.
Although all he gets this time is a fistful of feathers.
He checks another pigeonhole.
But nothing.
He's spoilt for choice.
So many pigeons, but which one to go for?
The pigeons all use the same tactic.
He needs to up his game.
He soars high to find a likely victim.
And dives at over 100mph.
It will be a welcome meal after such a long journey to get here.
Pigeons have succeeded by learning to adapt to our way of life.
They are now found on every continent except Antarctica.
As well as a few humble pigeons,
Australia boasts a colourful selection of native birds
that have also taken to urban living.
More species of parrot live here than in any other continent.
A dazzling array of over 50 varieties.
As well as in Sydney,
rainbow lorikeets are found all along Australia's east coast.
The popular Gold Coast is also one of their favourite locations.
These cheeky birds have adapted their lifestyle to our own
and now prefer the sweet delights of city parks and gardens.
They can't resist ripe fruit, especially the cultivated varieties.
After a spot of scrumping, their thoughts turn to romance.
The males try to impress the opposite sex by clowning around.
It usually works.
Parrots have proved very successful at breeding in our backyards.
Even in the outback,
parrots have multiplied by living on our free handouts.
Cockatoos - thousands upon thousands of them.
They form huge raiding parties, laying waste the farms
and agricultural fields that bring riches to an otherwise barren land.
A life of petty theft means living on their wits.
They are the most intelligent pest a farmer is likely to encounter.
But one of the most familiar parrots of all lives a blameless existence
right in the heart of the outback.
Uluru, also known as Ayers Rock,
lies at the very centre of the continent.
It's remote spots like these that the budgerigar calls home.
This tiny parrot is the most popular of all pet birds
but, in the wild, it lives far from human company
in some of the driest parts of the outback.
For much of the time they flit around in small groups
just a few hundred strong,
sharing information on where the best food and water can be found.
These small search parties look for the wild grass seeds
that make up the budgie's staple diet.
Grazing animals such as kangaroos
show where ripe grasses are most likely to be found.
The budgies also watch what other flocks of birds are getting up to.
Gradually, the merry band gathers followers.
Soon, it numbers many thousands.
Then it grows to millions.
This is one of the largest flocks of budgerigars ever seen.
They now act like a super-organism,
pooling their knowledge to find the best sources of food and water.
With so many minds working together,
they have an overview of vast areas of the outback.
And, finally, they hit the jackpot.
A remote waterhole.
Wave upon wave take turns to drink.
Each bird has just seconds to swallow what it can
before another drops in to take its place.
But, wherever birds gather, so do their predators.
Black falcons take up residence,
confident that each day food will land right on their doorstep.
But thirsty budgerigars give them a run for their money.
Budgies can perform some of the fastest manoeuvres of any bird.
They are so skilled, they even sneak in a drink between attacks.
It drops like a stone just before the grab.
Again it falls, just out of reach.
Turning on a dime, it out-flies the falcon time and time again.
Despite their best efforts, the falcon and his partner go hungry.
A waterhole gives the budgies a break from wandering,
but once the local grasses have been plundered
the huge flocks will split into small roaming parties once more.
Back in the Himalayas, the weather has cleared.
The downed cranes have survived the days of bad weather
by raiding farmers' fields.
Himalayan villages have inadvertently become a lifeline
for migrating birds that run out of luck.
But the crane's presence isn't welcomed here.
The travellers are pushed further down the valley.
As the sun appears, the dry riverbed creates eddies of rising hot air.
They feel the welcome breeze and open their wings to catch it.
The demoiselles begin to levitate upwards, as if by magic.
With clear skies and a light wind, it seems their luck has changed.
But before them lies an even greater challenge -
a Himalayan valley of death.
Here, airborne predators patrol the canyon walls.
They've been expecting the cranes.
Golden eagles are among the waiting birds of prey.
They launch a high-speed ambush from the heavens.
The eagle singles out an exhausted crane.
The eagle is part of a double act...
..driving the crane into the talons of her mate.
They're well-practiced at this manoeuvre.
For the pair, it's now a game.
The rest of the flock make their escape.
But these hills have other eyes.
Peregrine and lagger falcons are the next big challenge.
Half the crane's size,
they rely on speed and sheer force of impact to kill.
But the crane reacts by dropping away,
reducing the speed of any collision.
The falcon's only hope is to knock it off balance.
This young crane isn't out of the woods yet.
She has been separated from her family
and is alone and exhausted.
Above, Himalayan vultures are starting to gather.
At this time of year, they make a good living from birds that perish on migration.
She'll need all the luck she can get if she is ever to see India.
The remote Himalayas aren't the only place where vultures can be found.
Back in Rajasthan,
these scavengers can make a living without leaving town.
Vultures were once a common sight over India.
Today, Jodhpur is one of the few cities where they still make a home.
Indian vultures now mostly live on roadkill,
but, if this fails, they'll find food the old-fashioned way -
waiting for one of India's most famous hunters to provide a meal.
They can fly for miles with hardly a wing flap.
The vulture's keen vision spots a tiger on the prowl.
Deer are a tiger's favourite prey.
And running deer ring the dinner bell.
Dinner is served.
But a vulture won't risk landing while the owner's around.
They gather and wait their turn.
But, suddenly, the tiger ups and leaves her prey.
She must have other things on her mind.
The vultures won't waste this golden opportunity.
But the reason the tigress left soon becomes clear.
She has young cubs.
At three-months-old, the cubs have started to eat meat.
It's time to give them a treat... if there's any left, that is.
The vultures are good at bolting their food
and retreating when the rightful owners arrive.
TIGER ROARS
This is no time for heroics.
The tigress returns just in time.
Her cubs won't go hungry today.
Back in civilisation,
the pigeons are also on the hunt for any scraps they can find.
Their travels take them over some of the most magnificent sights in this part of India.
The Palace of Winds in Jaipur.
The Lake Palace of Udaipur.
A favourite destination is one of the hundreds of temples that abound here.
Below, a stream of people are arriving bearing gifts of food.
Here, pigeons should reach Nirvana.
But these offerings are not for lowly pigeons,
they are for another scavenger.
One revered by the visitors.
Black rats.
Over 6,000 live in Deshnok Temple.
They are protected by the local people,
who believe the rats are their reincarnated ancestors.
It's tantalizing for the pigeons,
as it's the black rats that get all the gifts.
The rats enjoy their elevated status
and feel confident enough to chase off the competition.
To get a meal,
pigeons must snatch it from under the noses of these exulted beings.
If they can dodge the rats, there's plenty of food to be had.
But this is easier said than done.
Males box and fight each other for mating rights.
There are rats everywhere,
chasing each other and creating utter chaos.
And there's only so much a pigeon can take.
Having snatched some crumbs from the holy one's table,
they take a break outside,
but the temple forecourt has its own hazards.
A steppe eagle is on the prowl.
But this time the pigeons have some extra muscle.
Hooded crows act as their bodyguards.
They intercept anything that invades their airspace.
They work as a mob, taking turns to harass the eagle.
One nearly lands on its back.
Eagles depend on surprise.
Once he's been rumbled, he know he stands little chance of making a kill.
With the eagle sent packing,
the pigeons resume their never-ending quest for scraps.
Back in the Himalayas, the young crane is on borrowed time.
Overhead, lammergeiers join the other circling vultures.
It would be suicide for the crane to continue the journey alone.
She doesn't know the way.
The scavengers have decided her days are numbered.
But the migration season isn't over yet.
Suddenly, another flock, delayed by the weather, appears on the horizon.
It's just the help she needs.
With them, she'll find safety in numbers.
Together, they continue onwards through the pass.
The worst part of the crane's journey is now over.
Once the cranes put the Himalayas behind them,
the final hurdle is the Great Thar Desert -
a band stretching from Pakistan across North-West India.
A procession makes its way across the drifting sands.
These camel trains are just the start of something far bigger.
Pushkar Fair - the greatest gathering of camels anywhere on Earth.
Here, these "ships of the desert" are traded by local tribes.
But, of course, wherever people gather, so do the pigeons.
With so much animal feed around, this isn't their greatest challenge.
In fact, for the next five days, they will have everything they could wish for.
They just have to learn the camel's feeding times.
Pigeons are endlessly adaptable. It's the secret of their success.
For most of the time these pigeons scrape a living in desert towns
but, once the yearly fair arrives, they join in the festivities.
But everything comes with a price.
A feral cat is on the prowl.
This is no domestic moggy.
Her hunting skills are essential for survival.
At first, it all seems just too easy.
But she soon realizes she must raise her game.
Her hunting skills are as good as any tiger.
They may not escape predators all the time,
but by adapting to every aspect of human life,
pigeons have become one of the most successful species on the planet.
The mysterious, ancient landscape of China.
The people here have a long association
with some special birds that arrive each year.
Swallows and swifts have been revered down the ages
as bringers of peace and tranquillity.
They are one of the very few animals
that are welcomed into people's homes.
Red rump swallows use the mud at the edge of paddy fields
to construct their nests,
but, as payback for being allowed to nest, the birds return the favour.
The swallows hunt along the forested hillsides and rice fields for food,
ridding the countryside of crop pests and biting insects.
They are found throughout China.
Many nest on the watchtowers of the Great Wall.
Down the centuries, swifts have even been encouraged
to nest in the ancient eaves of the Forbidden City in Beijing.
A tradition that continues today.
And amid the modern chaos of the ancient city of Xian,
it's the ancient bell towers that swifts use to make their home.
Here, they act as pest controllers, catching the wood-boring insects
that could destroy these revered buildings.
Their labours are repaid by tolerance and respect.
Also in the Orient,
Japan has taken other species of migrating birds to its heart.
The onset of winter marks the arrival of whooper swans
to the northern island of Hokkaido.
They too are escaping the even harsher winters found in Siberia.
They have travelled 2,000 miles to get here.
But they have a problem.
The lake they are returning to is frozen.
They are one of the world's heaviest flying birds
and usually rely on water to cushion their landing.
Landing on ice requires an unfamiliar set of skills.
Each bird has to rapidly devise his own technique.
It's like water skiers trying to use their skis on snow.
The huge webbed feet are mainly used as paddles
but they also help spread the load when landing on water.
On ice, they just get in the way.
It can easily go horribly wrong.
Where the ice has thawed, the swans make a more controlled landing.
The water is warmed by hot springs from below,
so it rarely freezes completely.
It has become the favourite winter wonderland
for most of the swans in Japan.
They know that there will always be open water somewhere.
Whooper swans pair for life and couples celebrate their arrival.
But this doesn't stop single males trying to muscle in.
Soon, peace is restored.
The strength of the swans' relationship
is displayed through the symmetry of their greeting.
Above their heads, Japan's most revered bird is also arriving.
Japanese cranes.
The arrival of the cranes has been considered a symbol
of good luck and fidelity for centuries.
They are so admired,
every winter the local people venture out on to the ice to feed them fish -
a welcome handout in harsh times.
These gifts of kindness have seen the population of cranes grow
from just 33 in 1952 to over 1,200 today.
It's now such a prime spot, many have stopped migrating altogether.
The local crows have grown in number too.
But it's not all Zen serenity.
A red fox.
He can easily tackle a full-grown crane.
But the fox is not their only concern.
White-tailed eagles are gathering too.
In winter, these bird-hunters move inland from the coast.
Then the emperor of eagles arrives - a Steller's.
One of the biggest eagles in the world.
The cranes are outnumbered by some of their worst enemies
but none try to get away.
These brave birds are quite prepared to stand their ground.
They know they are not the eagle's real target.
For, here, a strange alliance has developed.
The predators have learnt to scavenge on the free handouts meant for the cranes.
In this surreal gathering, predators lay down their arms
and call a truce with their former prey.
It's a strange and temporary amnesty but one in which everyone benefits.
The change of behaviour of all these birds
is brought on by the nation's love of the Japanese crane.
Back in India, migrating demoiselle cranes
have also gained from the kindness of the local people.
They've travelled 2,000 miles to reach here.
In the past, many would have spread out across India.
But, today, 9,000 of these wetland birds
choose to converge on a town in the heart of the desert.
It's the last place on Earth you would expect them to go.
They circle over the town of Khichan, waiting for a sign.
And then below, in a barbed wire compound,
a local man scatters grain.
As ever, the pigeons won't miss out on free lunch,
even if the offerings aren't for them.
But it's the cranes that the villagers want to attract
and these visitors could hardly be more welcome.
These normally timid birds descend among the villagers
to collect their reward.
Like the Japanese, the people here treasure the return of the cranes,
scattering grain each day to encourage them down.
What was once a quick desert stop-over
has become a place to spend the entire winter.
The cranes have even changed their migration routes to converge on this welcoming spot.
They have been fed here for decades
and in the very centre of this desert town, they know they can find safe haven.
Now, so many birds come here,
they consume an extraordinary 5,000 kilos of grain each day.
The compound has been built for their protection.
And, on the other side of the fence,
a second shift of cranes waits in the wings.
Each knows its allotted dinner time.
When those inside have had their fill they change places,
leaping back over the fence and allowing the second sitting to begin.
In this most unlikely of places,
one of the greatest bird spectacles on Earth can be found.
It's a gathering that only exists
because of the villagers' devotion to the birds.
Back in Japan, tranquillity has been restored.
The cranes begin one of the most intricate
and beautiful courtship dances in the world.
Japanese cranes can live for 60 years or more,
making their partnerships among the most enduring of any bird.
These dances keep their relationship strong.
It's an event that has been encouraged
by a special partnership between birds and people.
It's relationships like these that have sustained countless species,
from the parrots of Australia to the vultures of Jodhpur.
Even the humble pigeon finds sanctuary
wherever man makes his home.
Next time, we will look at the close relationships
between birds and people
that allowed Earthflight to spread its wings and fly across the world.
Subtitling by Red Bee Media Ltd
E-mail subtitling@bbc.co.uk