This is our planet's hothouse - the jungle, the tropical rainforest.
Forests like these occupy only 3% of the land, yet they're home to over half of the world's species.
But how do so many different kinds of plants and animals find the space here to live alongside one another?
On the dark, humid forest floor, the jungle appears to be lifeless.
Often the only signs of life are what you hear.
BIRD SCREECHES
A male blue bird of paradise is advertising for a mate.
It's quite a performance, but he's not the only bird of paradise here keen to make an impression.
There are nearly 40 different kinds on the island of New Guinea,
each with a display seemingly more bizarre than the rest.
BIRD WHOOPS
BIRD SQUAWKS
A rifle bird of paradise.
BIRD SQUAWKS
Like many jungle animals, birds of paradise avoid competing with each other,
and these do so by living in different parts of this jungle-covered island.
The six plumed bird of paradise displays in his special clearing on the forest floor.
The magnificent bird of paradise favours the low branches of bushes.
His female is modestly dressed.
BIRD CHIRPS
The male has a good set of lungs, but he'll have to do more than
flutter his eyelids if he wants to impress her.
It'll all depend on his performance.
The females may be dull looking but they're very picky.
And it's time for a really close inspection.
His right side looks fine, but what about his left?
Pretty impressive, but is he magnificent enough?
Oh, dear! Her departure says it all.
Generations of choosy females have driven the evolution of these remarkable displays.
The more extravagant a male is the more likely he'll be noticed.
CLICKING
New Guinea lies in a warm tropical belt that girdles our planet around the equator.
With abundant rainfall and twelve hours of daylight, 365 days a year,
it's here that rainforests flourish.
Surprisingly, only 2% of the sunlight filters down to the forest floor.
Down here, seedlings struggle to grow.
But the gloom is not eternal.
CREAKING AND SNAPPING
LOUD CREAKING
The death of a forest giant is always saddening
but it has to happen if the forest is to remain healthy.
The sudden blaze of sunlight will bring life to the forest floor.
A single hectare of rainforest may contain as many as 250 species of tree.
That's nearly ten times the number that grow in Britain.
And the thirst for light triggers a race for a place in the sun.
There's no time to waste.
A seed that may have fallen only a few days ago now bursts through the leaf litter.
With so many competitors, getting a good start is critical.
But each plant has its own particular strategy for making the most of this rare opportunity.
The seeds of hardwoods are quick to germinate,
but like the fabled tortoise, their strategy is to be slow and steady.
Vines and other climbers put all their energy into rapid vertical
growth rather than girth, though they'll need to be well supported.
The climbers' strategy looks chaotic, but there's method in their madness.
Their growing tips circle like lassos, searching out anchors for their spindly stems.
They put coils in their tendrils so that if their support moves they will stretch and not snap.
But the front runners at this stage, the first to fill the clearing,
are pioneers like the macarangas.
Their immense leaves capture huge amounts of sunlight, so fuelling their growth.
As a result, the macarangas grow a remarkable
eight metres a year, surging ahead of almost all their rivals.
In the race for the top spot, hundreds will start, yet few will ever reach the finishing line,
their growth cut short by the diminishing light.
In less than four years the gap will have gone,
but that's not the end of the race.
The ultimate winners are the tortoises, the slow and steady hardwoods.
When the short-lived pioneers have fallen, it's the hardwoods that take their place
and a 50 metre giant, like this one,
may keep its place in the sun for another two hundred years.
At the top is the canopy, the engine room of the jungle.
It's up here that most of the animal life in a rainforest can be found.
But despite the apparent abundance of vegetable food,
gathering it is seldom easy.
With no real seasons, each tree flowers or fruits at a different time
of the year, which means that food is very widely spaced.
Monkeys, like these tamarins, must search the canopy for all kinds of food if they're to survive.
But across the world's rainforests there's one type of fruiting tree that always delivers -
the fig.
Wherever they grow, figs are a magnet for a great diversity of animals.
In the Amazon, the first to appear are the spider monkeys.
These large primates are big fig eaters, but they won't have the tree to themselves for long.
Others will want a share.
Like the diminutive emperor tamarins.
The tamarins love figs too, but being petite means they're easily scared off.
Squirrel monkeys are also small but they have strength in numbers.
Their timeshare on the tree may be short, so their tactics are more smash and grab.
Capuchin monkeys are the bully boys in these forests and they want the ripe figs for themselves.
Figs are one of the few trees that fruit the year round
so when other food is scarce these fruits are always available somewhere or other.
Even for leaf eaters, like howler monkeys, the ripe figs are just too good to miss.
And howlers are too big for the capuchins to chase off.
Figs are so popular that as many as 44 different kinds of bird and monkey
have been seen working a shift system on a single tree.
Because fruiting trees are so valuable, many monkeys are territorial.
And if you live in the tree tops, there's perhaps no better way of
staking your claim to a territory than this.
GIBBON WHOOPS
The calls of the siamang gibbons begin as a duet between the dominant male and female.
The rest of their family soon join in
and it results in a frenzy of activity.
RAPID WHOOPING
The calls can carry over a mile and their message is clear.
WHOOPING GROWS LOUDER
They tell any neighbouring siamangs, "This is our territory - keep out."
Up here, the calls of siamang gibbons seem to dominate the airwaves
but with the jungle's incredible diversity there are countless others trying to be heard too.
WHOOPING
BIRD CALLS
Every layer seems to beat to a different tune.
CHIRPING
HOOTING
BIRDS CHIRP
In the early morning, the forest's chorus is particularly rich.
Sounds travel further in the cooler air.
LOW WHOOPING
But few calls can penetrate as far through the dense vegetation
as this one - the deep bass solo of a male orang-utan.
LOW WHOOPING
In the middle of the day, little stirs in the jungle and the hot dense air muffles the sound.
As the afternoon wears on, a different set of players begin to warm up.
Insects work in harmony, timing their calls to fall between the notes of others.
INSECTS CHIRP AND WHIRR
Many singers stick to precise schedules.
Right on cue, the six o'clock cicada.
HIGH-PITCHED DRONE
Night brings out a whole new orchestra.
OVERLAPPING FROG CALLS
The cacophony of competing calls seems deafening to us,
but frogs' ears are tuned to hear only the calls of their own kind.
FROGS CROAK
The songs of courtship echo from all around.
Male gliding leaf frogs leap from the tree tops.
To slow their descent, they use their huge webbed feet as parachutes.
These large tree frogs spend most of their lives
in the high canopy and only come down when it's time to breed.
Once settled, they begin to serenade their unseen females.
Now it's time for the females to make their move.
There's no shortage of suitors, but this female
has already made her choice.
She's heading toward the loudest call, because loud calls come from big frogs,
and big is best.
But to reach him she must run the gauntlet of a gang of smaller suitors.
Their only chance of mating is to make a sneaky interception.
He's scored, but with more females arriving all the time,
it's not over until the fat frog stops singing.
Feet so vital for gliding are now put to other uses.
Two's company.
Three's...inconvenient.
But, in any case, all male frogs are equipped with dry thumbs
which enable them to get a vice-like grip on their moist partners.
It's a case of first come first served.
Living in such a humid environment means jungle frogs are less tied to
puddles and pools and these even lay their eggs out of water.
There's little chance of them drying out, and up here they're safer from predators.
Surprisingly, it doesn't rain every day in a rainforest,
but more still falls here than anywhere else on earth,
on average over two metres a year.
A single tree can suck up hundreds of tons of water each year.
But the trees can't use all this water, so much of it returns
to the air as vapour, forming mist and clouds.
In the Amazon, the largest unbroken stretch of rainforest in the world,
half of all the rainwater that falls
comes from clouds produced by the trees themselves.
With so much rain, it's not surprising that many of
the world's largest rivers are found in rainforests.
Inside the forest, the high humidity creates the perfect conditions
for a strange world where life is built on decay.
Amoeba-like slime moulds cruise the surface, feeding on bacteria and rotting vegetation.
Fungi also flourish on decay.
These are the fruiting bodies of the fungi, the only visible sign
of a vast underground network of fungal filaments.
In temperate forests, the build-up of leaf litter creates rich stores of nutrients.
That, however, doesn't happen here.
Nutrients that reach the soil are leeched out by the rain,
but fungi are connected to tree roots by their underground filaments
and by quickly consuming the dead
they help to recycle crucial minerals straight back into the trees.
And this recycling happens faster here than anywhere else on the planet.
There are thought to be nearly a million different types of fungi
in the tropics, the vast majority still unknown to science.
But one thing's for certain - without fungi, rainforests could not exist.
Nothing goes to waste in a rainforest.
The fungi become food for others, like these beetle larvae.
Finding the fungus isn't a problem for the grubs since their caring parents actually show them the way.
Incredibly, 80% of all insects live in jungles.
Few are more successful than the ants - there can be eight million individuals in a single hectare.
But jungle ants don't have it all their own way.
These bullet ants are showing some worrying symptoms.
Spores from a parasitic fungus called cordyceps
have infiltrated their bodies and their minds.
Its infected brain directs this ant upwards.
Then, utterly disorientated, it grips a stem with its mandibles.
Those afflicted that are discovered by the workers are quickly taken away
and dumped far away from the colony.
It seems extreme, but this is the reason why.
Like something out of science fiction,
the fruiting body of the cordyceps erupts from the ant's head.
It can take three weeks to grow
and when finished the deadly spores will burst from its tip.
Then any ant in the vicinity will be in serious risk of death.
The fungus is so virulent it can wipe out whole colonies of ants.
And it's not just ants that fall victim to this killer.
There are literally thousands of different types of cordyceps fungi
and, remarkably, each specialises on just one species.
But these attacks do have a positive effect on the jungle's diversity
since parasites like these stop any one group of animal getting the upper hand.
The more numerous a species becomes, the more likely it will be attacked by its nemesis, a cordyceps fungus.
With so much competition,
jungles have become the home of the specialist
and this animal, from the island of Borneo, is one of the most unusual.
It's a colugo, or flying lemur,
though this is something of a misnomer
as it doesn't actually fly and it certainly isn't a lemur.
In fact, nobody's quite sure who its closest relative is.
The colugo depends on a diet of young leaves, and to find enough of them
it must move from tree to tree.
The leaves are not very nutritious
but then getting around doesn't use much energy.
In a single night, a colugo might have to travel as far as two miles,
but that task is made easier by its superior gliding skills.
The secret of success in the competitive jungle is specialising
and this has led to the evolution of some very intimate relationships between plants and animals.
These are pitcher plants, also from Borneo.
Adapted to living in very low nutrient soils, the pitcher plant
gets most of its nourishment from insects lured to nectar glands
on the underside of the lids.
Once on board, the waxy sides of the pitcher ensure there's little chance of escape.
Most slip to a watery grave.
At the bottom of the pitcher, glands secrete enzymes
which help to digest the corpses, so feeding the plant.
But not all visitors have a fatal attraction to the pitchers.
The red crab spider spends its entire life in the pitchers, hanging on with threads of silk.
Instead of building a web, it relies on the water-filled pitcher to trap its food.
When an ant falls in, the spider simply waits for it to drown
and then abseils down for a spot of fishing.
Alive, this ant would be far too dangerous for the spider to tackle,
so using the pitchers as traps means it can get bigger meals.
And the spider doesn't rob the pitcher of everything.
The digested remains of its booty will end up in the water, providing instant food for the plant.
Other food, like mosquito larvae,
seems to be out of reach, but the spider has another surprising trick.
By taking its own air supply, trapped in a bubble,
the crab spider can actually dive to the very bottom of the pitcher.
Once the prey is captured,
the spider hauls itself back up its silken safety line.
The pitcher is a one stop shop for this spider, but it's not alone.
In a jungle, there's competition for everything, even a small water-filled pitcher plant.
Such specialists create the jungle's remarkable diversity.
But finding enough food to survive is so challenging that most animals
living here tend to be small, though there are exceptions.
This is the Congo in Africa.
It's a vast wilderness, and the least explored of all jungles.
From up here, the forest looks similar to the ones that grow in the Amazon or South East Asia,
but down below there are some unexpected sights.
Criss-crossing this forest are countless miles of highways,
and they were made by something big.
Forest elephants roam great distances
in their search for food,
but to survive they must emerge
from the gloom of the forest.
And clearings like this one
are a magnet for elephants from far and wide.
These elephants live in much smaller groups than their savannah cousins.
This might be the first time that one group will have seen another for a month.
For the adult males, it's a welcome break in an otherwise largely solitary existence.
And they're not the only animals attracted to the clearing.
Forest buffalos and red river hogs are also regular visitors,
as are bongos, which are very difficult to see outside these clearings.
All these large forest animals have come here to collect
an essential element of their diet that lies buried beneath the mud.
And the elephant's trunk is the perfect tool for reaching it.
To get what they seek, the prospecting elephants must first blow away the covering layer of silt.
Satisfaction at last!
They're collecting a particular kind of clay that contains vital minerals scarce in their natural diet.
It may be mud, but there's just nothing quite like it for enriching the blood.
The clay also helps to absorb the toxins found in many leaves that the elephants eat.
There are other benefits to coming here.
These clearings are the only places where the forest elephants can get together in such numbers.
When they return to the forest, they will have to go their separate ways once more.
If large animals are rare in jungles,
then groups of large animals actually living together are even rarer.
This posse of hunters is not only formidable, it's also very large.
In their search for food, chimpanzees move effortlessly between the forest floor and the canopy.
They're one of the few jungle animals able to do so.
Figs are a vital part of a chimpanzee's diet and some just can't seem to get enough of them.
But there's something special about this stretch of forest in Uganda.
Fruit is actually abundant.
And a lot of food supports lots of chimps.
At 150 strong, this community of chimps is the biggest yet found in Africa.
Their numbers are so large that they need a big territory,
lots of fig trees, and they're willing to fight for it.
HIGH-PITCHED WHOOPING
THEY GRUNT
These calls announce the start of a raid into land controlled by their neighbours.
As they leave their core zone, the patrol goes silent, occasionally stopping to listen.
Signs of the enemy are detected and examined closely.
The chimp militia are now at the very edge of their territory.
All need to be on maximum alert.
They must wait and listen.
DISTANT SCREECH
An unfamiliar chimp call raises the tension.
It's an uncertain time.
The size of the rival group is as yet unknown.
Not far away, their neighbours are feeding in a fig tree,
oblivious to the approaching dangers.
The patrol moves off with a sense of purpose.
They must remain silent until they close in on their rivals.
CHIMPS SCREECH The attack is on!
To intimidate their opponents, the aggressors scream and drum on buttress roots.
SCREECHING
Several males corner an enemy female.
It's a ferocious attack and she's lucky to escape with her life.
Others are not so fortunate.
CHIMP WHOOPS
The battle won, a grisly scene unfolds.
An enemy youngster has been caught and killed.
The carcass is shared between members of the group and eaten.
Killing a competitor makes sense if you want to protect your food supply.
But exactly why they cannibalise the dead chimp is not fully understood.
It may simply be a chance for some extra protein.
Teamwork has brought this group of chimps great success, but they'll soon reach the limits of their power.
The competition for resources ensures that no one species dominates the jungle.
The rainforests' great diversity has come at a cost.
It has made them the most finely balanced ecosystems in the world, only too easily upset and destroyed
by that other great ape, the chimpanzee's closest relative...
ourselves.
Filming unique behaviour for the first time often means long periods in hides.
And nothing demanded more patience than cameraman Paul Stewart's trip to film displaying birds of paradise.
The location for the bird of paradise filming was the Tari valley
in the remote jungle-covered highlands of New Guinea,
a place completely cut off from the outside world until the 1950s.
It's home to the Huli people whose support was going to be vital to the success of this shoot.
After negotiating with the local landowners
for access to the neighbouring jungle, the team were ready to begin.
The first job was building the hides.
This had to be done quickly to avoid disturbing the bird.
Each bird of paradise has its own favourite display site.
Finding them would have been almost impossible without local expert Joseph Tano.
The plan was to film three species of birds of paradise here, which meant setting up three different hides.
The next morning, the team were up bright and very early.
It seems the bird of paradise is the original early bird.
It displays very, very early in the morning
and that means we have to get up even earlier, normally about 3.45.
If we don't get up earlier than the bird we're gonna scare it
and that means eight hours sat in a hide for no reason.
ENGINE STRAINS
Obstacles to progress appeared sooner than expected.
Look at what the bridge is made of. It's not gonna support...
I don't think that's gonna support the truck!
With the vehicle stuck, the last part of the journey had to be made on foot.
Arriving later than planned meant extra care was needed
getting into the hide if the birds were not to be disturbed.
Paul's solitary vigil was about to begin. You might think that
to film something as showy and exotic looking as a bird of paradise
you'd need to trek into the deepest, thickest rainforest.
Funnily enough, Paul's hide is just at the bottom of this field about 100 metres away.
It's funny that while we have bluetits in our back garden, the Hulis have birds of paradise.
For the next six hours, Paul sat in the hide.
And at midday, when there was no chance of disturbing the birds, it was time for an update.
Good news or bad news?
Good news first. Good news it's not scared of the hide.
Bad news we're in the wrong place. So we're gonna have to move it.
Need to do it quick before it moves off.
It's really frustrating - I can see it,
if I crouch down there, it's somewhere in a line up here,
but I couldn't move the camera to it. It would've been way too noisy.
While the hide was being moved, the rest of the crew busied themselves with some bridge building.
Well, due to the incident this morning, we've decided to do some running repairs to this bridge.
Unfortunately, these beautifully hewn planks won't necessary be here in the morning, since the original
planks were taken by an enterprising local to build a house, apparently, and this is premium firewood.
The gaps filled,
a man and his pig were willing to give it the once over.
The pig looked none too sure.
Back at the hide,
things were looking up. Here at least was one
of the birds of paradise the team wanted to film - the male six plumed bird of paradise.
But Paul needed him to display and he wasn't going to do that unless a female showed up.
So both bird and cameraman were now waiting for the girls.
Exactly how long they would both have to wait was anyone's guess.
Hours ticked by without any development
and the boredom was beginning to take its toll.
One of the things about sitting in a hide for eight hours in a day is
that you start to mull things over in your head
and it's the classic scenario where a song that you don't particularly like, or in fact even hate,
comes into your head, and while I was waiting for these birds of paradise I had...
it was kind of a one hit wonder from the '80s which was My Bird of Paradise, I just sit and wait...
# Sweet bird of paradise... #
And it was going around and around and around and it was like my own brain was sabotaging me.
The male kept busy tidying up his display site, but sadly all his efforts went unnoticed.
Ten days went by without a hint of a female
and when things go wrong one can't help speculating why.
Was it the weather or the amount of food in the forest?
I think one of the problems is that,
with the lack of rain, the fruits haven't ripened, now we've got rain and it's getting a bit warmer,
I think the fruits may ripen,
and we're going to get all three species in one day.
Yes. You reckon?
I think optimism's good, Paul, because otherwise we sink into despair.
Judging from some of the looks, the Huli seem to share our disappointments.
But there were other things to feel positive about.
The bridge remained intact.
And when the truck got stuck in another rut,
there was a group of villagers only too willing to help out.
If only the female birds of paradise could be half as obliging.
Paul had now spent
more than 90 hours in this hide.
# My bird of paradise... #
But if birds of paradise weren't in the displaying mood, that wasn't true of the Hulis.
Just a short distance from where Paul sat, a festival was taking place.
The Hulis have been using birds of paradise feathers in their headdresses for centuries
and their traditional dance has an unmistakable similarity
to that performed by the original owners of the feathers.
SINGING AND DRUMMING
It was certainly very impressive, though naturally no substitute for the real thing.
A hundred hours on, both Paul and his subject were becoming
equally frustrated by the lack of females.
# Sweet bird of paradise... #
The shoot was beginning to go down,
and news that the team now had to film the displays of three birds of paradise in one week
filtered back to the locals.
LAUGHTER
All very amusing, unless you were Paul.
I'm surprised he's not a gibbering wreck by now.
He's had 8 to 9 hours in a hide a day, for just under five weeks.
I think he's had about five filming opportunities.
I mean, even by the standards of wildlife filming, that shows a high degree of patience.
And the siting of one hide meant he actually had to stand up for about a week, most of that in the rain.
I mean, that seems more like a cruel and unusual punishment
than an opportunity to film one of the great natural spectacles.
Fortunately, when it comes to wildlife filming, patience
sometimes pays off and a female bird of paradise finally appeared.
120 hours on, it was at last something to dance about.
Filming the displays of the other species was barely any easier.
And after nearly 300 hours in hides, one can only wonder how many times
Paul sang My Bird of Paradise to himself.
# My bird of paradise... #
Subtitles by Suzanne Macdonald Red Bee Media Ltd 2006
Email: subtitling@bbc.co.uk