Original subtitles

For 500 years, these birds have been

surrounded by myth and glamour.

And I've got to confess that I've been fascinated by them

for most of my life.

This is just one member of a hugely varied family

that, to my mind, includes the most spectacular

and beautiful birds on Earth.

The birds of paradise.

And what's more,

they throw light on some of the great mysteries of evolution.

Why have the birds of paradise become the most diverse, bizarre

and beautiful of all bird families?

Why have they developed the most extravagant plumes

and adornments of any group of living things on Earth,

so that sometimes, they almost cease to look like birds at all?

And why is it that this extraordinary family

is largely restricted

to one jungle-covered island in the Pacific?

TRILLING

Explorers and scientists

have been puzzling over these questions for 500 years.

Even today, by using the latest filming techniques,

we are making new discoveries about their behaviour.

This surely is one of the most spectacular sights

anyone could see in the natural world.

The mystery of the birds of paradise

began back in the 16th century.

In 1522, a ship returning to Europe

from exploring the mysterious islands of the Far East

brought with it, amongst other marvels,

three extraordinary skins.

They were very like this one.

You can see it's a bird - there's its beak, and its head.

And here are these long, feathery plumes.

But it has no wings...

and no feet.

The explorers had been told that

that was because these birds lived in paradise.

The ship concerned was one of five

that had set out in 1519

to sail around the world for the very first time,

under the command of the Portuguese explorer Ferdinand Magellan.

They endured catastrophic tropical storms and shipwrecks.

Magellan himself was killed in a tribal war in the Philippines.

But after three gruelling years,

the Victoria, the sole surviving ship, arrived back in Spain.

It was loaded with wonders and treasures,

including those first specimens of birds of paradise.

Magellan had been presented with these skins by a king

in the Spice Islands - the Moluccas, as we call them today -

in eastern Indonesia.

When Magellan's men asked why they had no wings or no feet,

the people had a problem,

because they themselves had never seen the birds alive.

They had been traded to the islands

from islands even farther to the east.

So they made up an answer.

They said, "Well, it's because the birds float high in the sky,

"among the clouds, feeding on dew,

"and human beings only see them when they die and fall to the earth."

So the first descriptions of these "birds of the gods"

were far from first-hand.

Yet they were accepted as fact by Europeans.

This was one of the very first paintings of a bird of paradise,

and it appears in the margin of a book of prayers

written in 1540,

to show the devout the sort of creatures

they might expect to see when they got to paradise.

But it wasn't only the pious who were interested in the discovery.

So were naturalists.

But their understanding of the birds was similarly clouded by mythology.

This is the first volume in a great encyclopaedia of natural history

published in 1599 by an Italian called Aldrovandus.

And it's full of remarkably accurate pictures and descriptions.

There's a toucan, for example.

And here is a hornbill.

But turn another couple of pages...

..and a bird of paradise, without legs,

floating in the skies. No wings.

And here it is drinking dew from the clouds.

Aldrovandus was so respected that this view of the habits

of birds of paradise persisted well into the 17th century.

It's hardly surprising that these pictures are wildly inaccurate,

bearing in mind that they were drawn from those flattened skins.

After all, no-one in Europe had ever seen wings or legs

attached to these astonishing plumes.

So it was not unreasonable for Europeans,

who still believed in dragons and mermaids,

to accept that these birds lived in paradise.

But still no-one knew where the skins actually came from.

In fact, the birds come from New Guinea.

It's 1,000 miles long and lies just north of Australia.

And there, of course, the people knew perfectly well

the truth about the birds.

They hunted them for the sake of their plumes,

which they used as currency and in many of their important ceremonials.

My first opportunity to see these wonderful birds

came when I went to New Guinea back in 1957.

We saw a wide, fertile valley ringed with mountains.

This was our destination - the valley of the Wahgi River.

Within a few minutes of landing, I saw coming towards me

through the tall grass a party of tribesmen

wearing magnificent feather headdresses.

We filmed a celebration called a Sing-sing,

during which tribal people,

wearing spectacular headdresses of birds-of-paradise plumes,

gather together to dance and chant.

And I took these photographs.

They displayed them during their dances,

showing how wealthy each of the men were

by having these enormous headdresses.

That's Princess Stephanie's black tail feathers.

These are King of Saxony's feathers from the top of the head.

These are the red plumes of Count Raggi's bird of paradise,

and these the yellow ones of the Lesser.

When they came to have marriages,

a party going to collect a bride would have to take a gift

to the bride's parents of birds-of-paradise plumes.

And they arrange them on these great banners.

There's a front view of that with nearly two dozen sets

of bird-of-paradise plumes all around the side of the banner.

And down the middle there, gold-lipped pearl shells.

For thousands of years, the plumes have been traded

from this part of New Guinea right across Indonesia,

up into South-East Asia and beyond.

In Europe 400 years ago, many aristocratic families

possessed cabinets of curiosities

in which they displayed their collections of natural wonders,

and specimens of birds of paradise were amongst the most precious.

Their splendour even caught the eye of British royalty.

The young Scottish prince who was going to become Charles I of England

had his portrait painted with his furry hat on the table beside him,

and in it, his most treasured possession -

the plumes of birds of paradise.

Naturalists, seeking to curry favour with the aristocracy

and get financial backing for their expeditions,

promised to name any new species they discovered after their patrons,

and indeed they did so.

This is Queen Carola's bird of paradise,

with plumes on the top of his head.

This one was named after an Italian count,

Count Raggi's bird of paradise.

This one was named after Queen Victoria.

And this one is Prince Rudolf's bird of paradise,

though it's more often known these days as the blue bird of paradise.

And here is Princess Stephanie's bird of paradise,

with a great, long, glossy black plume.

Not all were named after royalty.

Napoleon Bonaparte's nephew, fired with republican zeal,

named this one Diphyllodes Respublica,

the Republican or People's bird of paradise.

But the popular version of the name didn't catch on,

and these days we call it Wilson's Bird.

Unlike the showy males,

the female birds-of-paradise are drab and brown in colour.

All look very similar, so you can well believe that they are related.

It's just the males with their extravagant decorations

that make the individual species look so different.

But even as late as the 19th century, no European

had seen anything of these birds except their dried skins.

And people wondered what the living birds must look like.

Errol Fuller, a collector who owns specimens

of 37 of the 39 known species of birds of paradise,

also paints them, and understands the difficulties involved.

The early painters of birds couldn't go and see these things in the wild,

and they couldn't see them in captivity,

so they were presented with something like this.

A dried, flattened skin that had been brought back from New Guinea,

and this was all they had to go on to make their painting.

This is a Black Sicklebill bird of paradise.

And the problem they had were things like this.

What on earth are these?

They look at first sight like wings. But they're not wings.

The wings are down here. They're just ornamental plumes,

and there are more ornamental plumes down here.

So, what did the bird do with these in life?

This is a mid-19th-century artist's answer,

and it's wildly inaccurate.

The Sicklebill actually displays like this.

It takes him a little time to work up to his full display posture.

There!

He lifts up those feathery tufts on his shoulders,

and holds them around his head so that he hardly looks like a bird.

And he repeats the performance on the same display post

up to five times every morning.

It wasn't until 300 years after Europeans saw the first skins

that anyone actually saw a bird of paradise displaying in the wild.

And the person who did so was the British explorer

Alfred Russel Wallace who, along with Darwin,

first proposed the theory of evolution by natural selection.

Alfred Russel Wallace was a great naturalist and scientist,

but he was not a wealthy man.

He earned his living by going to the tropics and collecting insects

and birds, and sending them back for sale to wealthy collectors

and to museums.

And he was obsessed with birds of paradise.

In 1854, he set off for New Guinea.

He became the first European ever to see birds of paradise display.

Here is his description of that sight.

"On one of these trees, a dozen or 20 full-plumaged male birds

"assemble together, raise up their wings,

"stretch out their necks and elevate their exquisite plumes,

"keeping them in a continual vibration."

"At the time of excitement,

"the wings are raised vertically over the back,

"the head is bent down and stretched out,

"and the long plumes are raised up and expanded

"till they form two magnificent golden fans."

Wallace's description amazed the world, and his book,

Travels in the Malay Archipelago, went on to become

one of the bestselling travel books of the 19th century.

I myself read it when I was about nine or ten,

and the frontispiece to the second volume fascinated me.

Here are the birds in display.

I yearned to go off and see such a sight for myself.

It was on that first trip to New Guinea in 1957,

for a television series called Zoo Quest, that I got my chance.

During the first month,

we saw plenty of plumes of birds of paradise on headdresses,

but none on the living birds.

At just one Sing-sing,

I estimated that there were 20,000 bird skins on display.

It seemed to me unlikely that we were going to find

many birds of paradise alive around here.

So we decided to travel somewhere further afield,

where there were fewer people, in order to find the living birds.

We went to the north to a valley that was then quite unexplored,

an "uncontrolled territory", as they called it at the time.

The people were really still living in the Stone Age,

making stone axes like this.

We had to cross rivers with locally made suspension bridges,

like this one.

Or even had to wade our way across,

and we had 100 porters carrying everything we needed -

food, gifts, cakes of salt, that sort of thing.

Eventually, we did find the birds.

The valley was throbbing with calls of Count Raggi's Paradise Birds.

As far as we knew, no-one had ever filmed the courtship dance

of these birds of paradise in the wild.

And this was to be our lucky day.

We could see his gorgeous red plumes

hanging from beneath his wings.

The plumes which make him so coveted and so desirable a prize

for all the people hereabouts.

And then suddenly, in a frenzy of excitement,

he threw his ruby plumes above his head, shrieking with excitement.

Our film, even if it was in black and white and rather fuzzy,

was the first record of a wild bird of paradise in display,

and showed exactly how he erected his plumes.

And this skin, which I found in a Paris flea market some years ago,

is of the bird that we filmed in black and white,

and here you can see how wonderfully rich its plumage was.

This a trade skin, just as the people prepare it in New Guinea,

without any legs and without any wings.

Both have been removed to emphasise the glory of these plumes.

After ten minutes,

he executed a final flutter and flew to another branch.

But this was only a single bird in display.

It was another 40 years before I saw the group display

of the larger and more impressive species,

the greater bird of paradise, that Wallace had described.

The birds are in another emergent tree just like this one,

and I've got an absolutely clear view of them.

This, at last, is Wallace's picture come to life.

Wallace described the display very accurately, as you would expect.

But he didn't understand why the birds were behaving like this,

in a group.

So even 300 years after the discovery of these birds,

the purpose of their displays still wasn't properly understood.

And it wasn't just the greater bird of paradise

that perplexed naturalists.

The second species of bird of paradise to arrive in Europe

at the end of the 16th century

appeared to be an even more bizarre-looking creature.

It still had a pair of golden plumes

sprouting from its flanks to justify it being called a bird of paradise.

It seems to have been painted soon after its arrival,

as the gold colour fades with time,

and, like the first ones, it had no wings or legs,

but it did have some extra, rather mysterious adornments.

This is it.

It's called the twelve-wired bird of paradise.

That's because it has thin, naked quills sprouting from the tail,

six on one side, six on the other.

What were such things used for?

Some people suggested that it wasn't natural

that they were curled up in this way,

that it happened because of the way the bird was packed.

Others suggested that maybe it roosted

by hanging from them upside down.

Nobody had any idea.

In the years that followed, more specimens of this bird appeared,

and other artists made a somewhat better job of depicting it.

But the function of those strange 12 wires remained a mystery.

It was only on my second trip to New Guinea in 1997,

when we filmed the bizarre courtship of this bird

for the very first time, that we found the answer.

Courtship seems to be some kind of game,

a variation of "I'm the king of the castle", perhaps,

only with a very special prize.

He deliberately brushed her face with his rear quills.

He's doing it again.

It seems that she prefers to be seduced, not by visual thrills,

but by tactile ones.

It may be an odd technique, but it works.

So it took 400 years from the arrival of the first skin

of the twelve-wired bird to actually record its courtship ritual

and finally solve the mystery of the peculiar adornments.

But there's another species

whose display is perhaps the hardest of all to interpret from its skin.

It doesn't so much flaunt its feathers

as use them to entirely transform itself.

This is the superb bird of paradise,

and it has this wonderful shield on its breast.

This blue colour isn't pigment.

It's reflected light, like that that comes from a thin film of oil.

So it changes according to how you view it.

But that's not its only decoration.

On its back it has a kind of cape.

These aren't wings, they are just feathers.

How would the bird have displayed that?

That was the problem facing 19th-century bird illustrators.

Artists did their best to work out

how the birds showed off their ornaments.

This version shows the superb bird's colours more or less correctly.

But otherwise, it's nowhere near the truth.

It wasn't until the late 20th century

that ornithologists managed to work out

just how the superb bird uses its feathers to transform itself.

These drawings by the Australian artist Bill Cooper

show just how it does it.

It uses these long black feathers, which form a cape on its back,

and brings them forward to form a funnel.

Then the green... Iridescent green breast shield

forms the base of the funnel.

And in the far depths, there appear to be two eyes staring at you.

In fact, they're not even eyes at all.

They're white spots on its head.

I think if in the 19th century any artist had suggested that

that's what the bird did, he really would have been ridiculed.

But no drawing can completely capture

the extraordinary way the superb bird transforms itself in display.

You just have to see the living bird.

CLICKING

The rhythmic clicks are made by flicking the wing feathers.

In 1996, I was able to watch Bill Cooper at work

as he painted another bird of paradise,

a Victoria Riflebird.

This is one of the few birds of paradise

that is found outside New Guinea or its offshore islands.

It lives in Australia, in northern Queensland,

where Bill Cooper also has his home, in an unspoilt patch of rainforest.

Come on, boy. Come on, gorgeous.

Oh, look at that colour!

Here he comes. Come on.

Oh, you are lovely.

As a young man, Bill Cooper travelled

through some of the wildest parts of New Guinea,

watching and painting the birds.

It was Count Raggi's that he encountered first, as I had done.

It turned and faced the female,

and then the male started shuffling towards her,

and he puffed out his chest feathers -

I'd wondered what they were for,

but he fluffed them out and formed a great pompom

through which his beak was protruding.

It was a great display.

Bill Cooper, to my mind anyway,

is the greatest of all bird-of-paradise illustrators.

And this one of the blue bird in display is particularly successful.

He's caught this wonderful intensity of blue

as the bird hangs upside down.

But what even Bill Cooper can't do

is to show that the male blue bird, as he hangs like this,

actually throbs this pattern here, making a noise at the same time

that sounds like some electronic equipment that's gone wrong.

Images of birds of paradise have become increasingly accurate

since those first attempts.

The plumed birds, in particular, that dance high in the trees,

became better known scientifically

as explorers and naturalists travelled more widely

through New Guinea's dense forests.

However, a few species display not up in the branches,

but on the ground.

They are more difficult to observe.

But we did manage to film one in display for the very first time

on my trip in 1997.

I have come to the island of Batanta.

It has its own species of bird of paradise that evolved here

and lives nowhere else.

One way of trying to get a look at it

is to put some leaves on this arena,

because this bird is meticulously tidy.

There he is!

Wilson's bird of paradise.

He's got his own fashion gimmick - the bald look.

There goes the first of the leaves that I dropped.

He is really quite small.

Only the size of a starling.

That looks like a female.

He's clearly not much of a dancer,

but with a costume like that, who would need to be?

What an amazing bird!

I've seen lots of coloured illustrations of them,

I have seen mounted specimens in museums,

but nothing has prepared me for the splendour of this wonderful thing.

Although Wilson's bird is very spectacular,

there are other ground-living species

with much more complex dances.

In 1876, an Italian explorer, Luigi D'Albertis,

spent many months charting the territory

of the then virtually unknown interior of New Guinea.

During one of his excursions through the forest,

his local guide pointed to a bird sitting on a perch in a clearing.

D'Albertis's first reaction was to shoot and skin the bird,

as he had done with every other specimen that he had collected.

And he was just about to pull the trigger

when the local man put his hand on his arm and said, "Wait."

Then D'Albertis became the first European ever

to see the display of the parotia bird of paradise.

This is how he describes it in his book.

"The bird spread and contracted the long feathers on his sides

"in a way that made him appear now larger,

"and again smaller than his real size."

"And jumping first to one side, and then on the other,

"he placed himself proudly in an attitude of combat,

"as though he imagined himself fighting with an invisible foe."

"All this time he was uttering a curious note

"as though calling on someone to admire his beauty,

"or perhaps challenging an enemy.

"The deep silence of the forest was stirred by the echoes of his voice."

And then he pressed the trigger and shot it.

GUNSHOT

"When the smoke cleared away,

"a black object lying in the middle of the glade

"showed me that I had not missed my mark."

"Full of joy, I ran to possess myself of my prey.

"But, as I drew near, my courage failed me.

"I could not stretch forth my hand.

"And, full of remorse I said to myself,

"'Man is indeed cruel.'

"The poor creature was full of happiness.

"One flash from a gun and all his joy is past."

Now, film-makers like Paul Stewart

hunt the birds not with guns, but cameras.

Using the latest ultra-sensitive filming equipment,

he captured the parotia's behaviour in meticulous detail.

The key to filming them

is for them to have no idea that you're there.

And the best way to achieve that

is to build a hide with the help of the local people.

You go in before first light, you leave after dusk,

and in between you are as silent as you humanly can be.

In 2005, he spent five weeks filming Lawes's parotia in action.

Eventually, he saw the male start to clear his display area or court.

And then he took a piece of damp leaf

and was shining the branch that the female would first come into

to judge his display.

It was as if the male was directing her to a specific vantage point.

Once he had polished the branch to his satisfaction,

he began his display.

He had a little bow tie almost of iridescent feathers,

but rather like a comedy bow tie, this thing would flick up and down

while he was displaying.

Now, we thought, "That's making a nice flash at ground level."

We should have suspected that there was more to it.

In fact, he was looking at and filming the bird

from the wrong angle.

It took another film crew to reveal why.

An American team decided to try and film

every single one of the 39 known species of birds of paradise.

Edwin Scholes and Tim Laman from the Cornell Laboratory of Ornithology

spent ten years crisscrossing New Guinea

in search of these birds.

There are four species of parotia and in one, Wahnes's parotia,

they discovered something new.

They placed the camera above the arena of a displaying male,

and so observed his dance from a female's point of view.

And it showed two details of the male's performance

that can only be seen from above.

The pennants on his head, seen this way,

form a vibrating arc around his skirt.

Then, iridescent lights appear to flash across the top of his head,

something you just can't see from the side.

And the bow tie of iridescent feathers

has very much more impact from above.

It is now known how the parotia breast shield changes colour.

The feathers are arranged so they overlap like scales,

and each feather has side filaments,

each of which has three different reflectors -

one that reflects an orange-yellow colour and two that reflect blue.

And these reflectors are at an angle to one another,

so as the bird moves,

the breast shield appears to change colour, like this.

And the parotia family held yet more secrets,

as Ed Scholes and Tim Laman revealed when they visited me in Bristol.

Nice to meet you! Where are we going to sit? Right here. OK.

I can't wait to see this stuff.

They had filmed the courtship display

of the Queen Carola's parotia, that I had never seen before.

Oh! I can immediately see it's different, with those white flanks.

There's a female there...

Oh, yeah. She's much lighter.

There's another at the back. Oh, yes. Three females now.

Four! They keep coming. Look at that, look at how intense they are.

Ah! It's starting. See this figure of eight,

where he's bouncing back and forth fluttering his wings.

If you were to trace the feathers on the back of his head,

and slow it down, it would make a perfect figure of eight.

And they're always perched above the display?

That's right. It's a really important part of the court.

The male selects that spot

because it has that perch for his audience to watch from.

And the audience really knows where the best place is.

The dance is facing upwards.

Here he is, see this hop and shake. Hop and shake.

He's transformed himself into this ballerina-like skirt shape.

He's positioning himself until he gets right underneath the female.

He goes into that dramatic pause.

All the females are leaning over, looking at him.

And as soon as he starts moving, they kind of relax and move as well.

THEY LAUGH

Go for it, boy.

He eventually mated with all six of those females.

This was the most successful individual bird of paradise

that we ever saw - this male was the king of them all.

This pause is terrific, isn't it?

"Come on, girls."

"This is it!"

By 2011, Tim and Ed, after 18 separate expeditions to New Guinea,

had succeeded in filming

every known species of bird of paradise in the wild.

We have come a long way from those first attempts

to make drawings of the birds,

which had to be based on no more than their shrivelled skins.

Then came paintings, and finally film of them -

eventually in colour.

But, of course, in the mid-19th century,

the only way to see a living bird

was to travel 8,000 miles to New Guinea,

because no-one had managed to bring one back to Europe alive.

It was Alfred Russel Wallace who once again was the pioneer.

In 1862, he succeeded in bringing back to England

two living birds of paradise.

The Zoological Society of London, the London Zoo, gave him �300.

An astonishing figure - worth about �30,000 today.

They were the first birds of paradise

to be put on display here, and they were soon the talk of the town.

In 1957, I set off for New Guinea, not only to film the birds,

but, on behalf of the London Zoo, to try and bring some back alive.

Although we managed to film the Count Raggi's bird,

I wasn't able to catch any.

But then I met a great naturalist and explorer

who had settled in the Wahgi Valley,

and had built aviaries in which he kept many of the species.

His name was Fred Shaw Mayer.

I found Fred with Bob, his hornbill.

Fred has been collecting animals all his life,

and in New Guinea alone, he's discovered five birds new to science

including one bird of paradise.

Fred gave me 13 birds of paradise of ten different species.

I set out with them on the five-week journey back to London.

And they ended up here in the old Bird House in the London Zoo.

It was quite a difficult journey.

We had to charter a little plane to take us to the island port of Rabaul

off the eastern end of New Guinea, and there we found an old cargo ship

that ploughed its way across the South China Sea to Hong Kong.

Every day, of course, they had to be fed and cleaned,

and we had plenty of fruit, but we discovered, as Wallace had,

that what the birds really loved was cockroaches.

And there were plenty of those to be found in the ship's kitchens.

Then, from Hong Kong, we got a freight plane back to London.

This big aviary here contains several of the birds of paradise

which we brought back.

That big one on the left

is the Princess Stephanie's bird of paradise,

one of the largest of the birds of paradise.

And here's one of the smallest - the King bird of paradise,

which is only a little larger than a robin.

It's a wonderful little bird.

Birds of paradise haven't been seen here in London Zoo since 1973.

But that's because it's now illegal

to export the living birds from New Guinea.

Nonetheless, there are just a very few places in the world

where captive bred ones can be seen.

I'm heading for one of them -

an unlikely location in the Middle East.

Thousand of miles away from the birds of paradise's natural home.

A sanctuary has been built especially for them

by a 21st-century royal collector,

Sheikh Saoud Bin Mohammed Bin Ali Al-Thani.

Here, in the middle of the desert of Qatar,

a breeding centre has been created for rare birds

and animals from all over the world.

The Sheikh has built Al Wabra, a state-of-the-art breeding facility.

There we are.

What about that?

Here at Al Wabra they are experts at caring for exotic birds,

like these wonderful Hyacinth Macaws,

the largest of all flying parrots and very, very beautiful.

They also maintain the largest captive breeding group in the world

of birds of paradise, with over 90 birds.

They get the best possible care,

with particular attention being paid to their nutrition.

They consume 160 kilos of papaya a week.

And their favourite insect food is mealworms.

Twice a day, freshly made,

the meals are delivered to each of the 90 birds individually.

Curator Simon Mathews is in charge of the birds,

and his aim is to understand them better,

and to improve their breeding success still further.

Because the eggs are so valuable,

Simon removes them from the nests to incubate them artificially.

This is a very special and precious chick.

It's a young greater bird of paradise,

and one of the very, very few that have been reared in captivity.

And Simon is now giving it one of its regular feeds.

He has to feed it every two hours, up to nine times a day

for nearly 20 days.

He whistles to attract its attention.

It's kept in an incubator for three weeks.

But the most difficult part of the breeding process in captivity

is getting the birds to mate without injuring one another.

In the wild, male plumed birds form leks, as in Wallace's picture,

where many males gather to show off their plumes to visiting females.

The female then chooses the male she admires the most...

..mates with him, but then quickly leaves,

avoiding the aggression that the males often show during mating.

The difficulty for Simon

is to ensure that the birds behave in the same way in captivity.

To protect the females,

he keeps the sexes separately and in alternate cages.

He watches a female

to see which side of her enclosure she spends most of her time,

which suggests to him which of the two males she prefers.

Once she appears to have made her choice, he opens a hatch.

And then she flies in to briefly visit her chosen partner.

Although courtship has been well documented in the wild,

few people have ever witnessed the birds nesting.

This is something I have never ever seen before.

I have been so fascinated by the beauty, drama and glamour

of the males with their splendid plumage and dances,

I have never spent time looking for the nest of the female.

And it's very unobtrusive, and very ordinary-looking.

It looks as though it might even have been made by a blackbird.

She makes it entirely by herself,

and in it, she lays her one single egg,

which she will rear entirely by herself.

Most other species of birds work together as pairs,

not only to make a nest, but to collect all the food needed

to rear their young.

And that difference is important in understanding

why birds of paradise behave in the way they do.

It's the fact that the female takes on the laborious business

of caring for the young by herself that is the clue

as to why the males have evolved such extravagant plumes.

Over the years, many naturalists have puzzled

over these fantastic plumes.

Why should this one family of birds

have taken feathered ornaments to such extreme lengths?

And surely, having plumes like this

must make it more difficult to fly,

and therefore make a bird more vulnerable to predators?

That certainly mystified Wallace.

He described the males' displays

as being nothing more than "playing" or "dancing".

But their real purpose is much more important than that.

This is a female King bird of paradise,

and you can see she is very drab.

Nothing like the glorious male.

And it was Charles Darwin who understood the important part

that she plays in the evolution of birds of paradise,

because it's she who selects a male

for the beauty of his plumage

and that, over many, many generations,

has led to the glories of the male.

Darwin called the process in which a female chooses a mate

based on his physical appearance "sexual selection".

And the great variety of male ornaments has evolved

simply because the females of a species have developed a preference

for a particular kind of plume or colour.

This trait, then, over many generations,

becomes more and more exaggerated

until eventually it can reach almost absurd extremes.

The two magnificent long, white tail feathers

of the ribbon-tailed bird of paradise

evolved because the female ribbon-tails

happen to like long, white tail feathers.

They are four or five times the length of the bird's body,

the longest tail feathers, in proportion to its body, of any bird.

The remarkable thing is that all these plumes, pennants and capes

have evolved from simple feathers.

Of course, they no longer serve the original function of feathers,

to keep a bird warm, or to help it fly.

Indeed, if anything, they are an impediment to flight.

Their only purpose is to impress the females.

And it is not only birds that find such plumes irresistible.

The people of New Guinea have always been well aware

of the biological purpose of these extravagant ornaments.

And when a tribesman puts on gorgeous plumes and feathers

and displays them in dances,

he is using them for the same purpose -

to display his desirability so a lady might select him.

DRUMMING

To prepare the skins and plumes,

New Guinea men still carefully remove the fleshy legs and wings

to reduce the likelihood of insect attack,

and to better display the plumes.

So the reason it was believed the birds had no legs

was because they had been removed before the skins left New Guinea.

But why has this particular family of birds

been able to take their ornaments and displays to such great extremes?

The answer lies in the nature of New Guinea itself.

The island is a relatively new one,

having been pushed up from the bottom of the sea

a mere ten million years ago - recently in geological time.

So few land-living mammals have managed to colonise it,

and most of those are harmless to birds.

Echidnas, that live largely on worms,

and a kind of kangaroo

that bizarrely clambers around in trees, eating leaves.

What's more, the lush, wet rainforests are rich

all the year round in sugary fruits.

And crucially, because the birds enjoy such a plentiful

and energy-rich food supply,

a female is able to raise her chick entirely by herself.

And that frees the males to spend a lot of time and energy

producing extravagant adornments and spectacular displays.

So, fruit, that plays such a significant role

in the Biblical view of paradise,

has also created a paradise for these birds.

Perhaps the name is apt after all.

It's now known that the complexity of a bird-of-paradise display

does not come entirely naturally,

as Ed Scholes has recently observed in young male riflebirds.

They start spending more and more time practising their displays.

Riflebirds are using their wings, moving them back and forth,

creating this interesting shape.

Taking a turn at being the male doing the practices,

and the other one is taking the role of the female.

Then they alternate.

And sometimes they're going on like this for hours,

and getting very carried away.

But when an adult male turns up, he sends them on their way.

And it's not only riflebirds that have to learn to dance.

Young male parotias start visiting display courts

when they're three years old,

before they develop the black plumage of the adult.

And they use this time to practise their dance moves.

It will be several more years

before this one will be taken seriously by a female.

It makes them look like a teenager, kind of strutting his stuff

in front of the mirror when he's not quite fully developed yet.

For five centuries,

birds of paradise have fascinated explorers and naturalists,

artists and collectors.

So it was a very special moment for me to get so close when,

because he had been hand-reared,

this male bird-of-paradise actually began to court me.

This surely is one of the great wonders of the natural world,

just as Magellan's sailors said it was 500 years ago -

even though, in fact, the bird does have legs.

The displays of the birds of paradise

have at last been recorded, both on canvas and on screen,

in all their exquisite detail and complexity.

Now, at last, we understand

that it is the rich character of their island home

that has allowed the birds to evolve in the ways that they have.

And it's the female's preference

for particular patterns, colours and displays

that have led to the males' astounding finery,

making them, surely,

among the most stunning and glamorous birds on Earth.

Millions of us watch clips of animals

showing what looks like friendship, affection