Original subtitles

DAVID ATTENBOROUGH: The very centre of Africa.

And the centre of two million square miles of dense tropical rain forest.

At first glance it seems deserted and eerily still,

not an easy place to live.

But, in fact, there is a greater concentration of animals here,

than anywhere else in Africa.

And in this world they must grab every opportunity.

Competition is intense and unrelenting.

Even the forest itself fights its corner with spines and poisonous sap.

Here, every living thing must fight for its space.

Such beauty.

But the flower is self-serving, enticing animals into an unwitting alliance.

Stingless bees.

They have to work hard. The forest flowers make them do so

by rationing their nectar, forcing each bee to visit, and so pollinate,

at least a thousand blooms each day.

(BUZZING)

For the bees, it's worth the effort.

They need the nectar to make honey which they store in pots.

It's so precious, they keep it hidden beneath the bark of a tree.

But their secret is out.

(CHIMPANZEE SHRIEKING)

Nothing is safe in this forest.

Chimpanzees love honey.

She seems oblivious to danger.

A fall from up here could be fatal.

But she does need a bigger stick.

Only a chimp has the ability to break into a stingless bees' nest,

as well hidden as this.

Chimps are extremely intelligent,

but none is born with the skill to use a tool.

Youngsters, like this one, must learn by watching.

She uses special tools, one after another,

to get all the honey she can,

and in a few minutes she destroys what took the bees years to build.

In the rain forest, nothing is safe.

Here in the Congo, there can be as many as 500 trees

crammed into every acre.

In the battle for space, some will rise to over 60 metres high,

in just a few decades.

In a valley like this, there could be close

on 1,000 different species of tree.

Up here, the crowns barely touch.

Each tree seems to respect its neighbour's space.

When they germinate down on the forest floor,

young trees and plants are less restrained.

But every new generation fights it out,

in battles we can see by accelerating time.

They must get light if they are to survive,

and they squeeze, crush and even slash one another in order to reach it.

Despite the thick canopy above,

some sunlight does filter through,

and allows a few low-light specialists to bloom near the forest floor.

Down here there are animals too that seek out the sunlight.

The forest's largest predator.

A female rock python.

Her body is five metres long, weighs 100 kilos,

and has 4,000 muscles

that she uses to crush the life out of her victims.

But right now, her need is not for food.

It's for warmth.

She finds a rare patch where a shaft of sunlight strikes the ground,

and she begins to bask.

She's cold-blooded.

So this is the only way she can raise the temperature of her body.

But now she's becoming very warm indeed, more than 10 degrees hotter than usual.

At 40 degrees centigrade she's in danger of killing herself.

Just in time, she moves off.

She disappears below ground.

(HISSING)

This is her nest,

and it's full of giant eggs.

It's critical for the eggs' development that they stay above 30 degrees.

Here in this special filming burrow,

she gently wraps her super-heated body around the eggs,

passing on to them the warmth of the sun.

She has done this every day for three months.

The repeated heat stress on her body is so great it could be lethal.

And at the very least, it will take three years for her

to recover from incubating this one clutch of eggs.

Her parchment-shelled eggs carry the pressed imprint of her scales.

An indication of the strength of her embrace.

At last, her efforts are rewarded.

But the babies can't stay here.

They must leave their sanctuary and find food

in the tangled world above.

They're over 60 centimetres long, already big enough to be a threat

to the smaller inhabitants of the forest.

But they are themselves vulnerable.

Particularly to other snakes.

But this one is their mother.

Unusually for snakes,

her maternal instincts continue for days after her eggs hatch.

Even so, the forest is such a dangerous place,

that only one in a hundred of her youngsters

is likely to reach adulthood.

Just occasionally, the competition eases.

A tree suddenly produces fruit.

(CHIMPANZEES GIBBERING)

It's a magnet for the creatures of the canopy,

and they, in turn, as they feed,

create a bonanza for those on the ground below.

A mob of red river hogs.

They have travelled over two miles through the thick undergrowth,

to get to this fall of fruit.

But in the African forest, little comes for free.

This feast is a bribe.

The hogs will carry the seeds in their stomachs

and deposit them far from the parent tree.

Night falls.

But one living community, which is neither animal nor plant,

continues its never-ending work in the darkness.

This ground is alive with fungi,

that digest all the litter discarded by the forest.

Some rare fungi do so with enzymes that are luminous.

The local people call them "Chimpanzee fire".

Without the fungi, the dead vegetation would pile so high

the living trees would be submerged.

Dawn.

And a new day reveals just how much control

the jungle has over its own environment.

The forests of the Congo are the lungs of Africa.

As they use the sunlight to build their tissues,

so they release oxygen and water vapour into the air.

Each hectare of forest produces

as vapour almost 190,000 litres of water a year.

So much that it creates its own weather.

Clouds blanket the forest,

driving up the humidity and temperature.

A storm is brewing.

The Congo might be the richest part of Africa,

but it's also the most violent.

(WIND WHOOSHING)

(THUNDERCLAPS)

Each year, as many as a hundred million lightning bolts strike the forest.

That's more than anywhere else in the world.

And with the lightning comes the rain.

Up to 95% of the rain that falls here is generated by the forest itself.

With the deluge will come change to the animals and to the forest.

It's certainly perfect weather for frogs.

The big storm is the cue for the most important climb of this frog's life.

It's a male in search of a mate.

But if he is to find one, he has to get to the top.

He needs to keep his wits about him,

for the rain also brings out hunters.

Easy does it.

The top at last,

(FROGS CROAKING)

but he's late to the party.

(CROAKING)

The higher a male sits, the further his voice will carry.

So the top slots are worth fighting for.

And he's won. He has the top place.

So now it's time to sing.

(LOUD CROAKING)

And a white-bellied female responds.

They join together to mate.

The loser will have to wait for the next storm, before he sings again.

She lays her eggs on a blade of a long leaf.

And he, using his back legs, folds it over,

and glues its two edges together, shutting the eggs inside.

This sealed nest is the safest place these leaf-folding frogs can find

to protect their precious brood.

Within days, the eggs are developing.

The timing is perfect.

The rain washes away the glue and the tadpoles slip out of the leaves

into the growing puddles below.

The rainy season reaches its peak and the ground has been transformed.

The forest is flooded.

It's a new world.

Fish swim in from the swollen streams, exploiting this newly-created space,

snapping up the drowning insects.

This is a butterflyfish.

A Congo bichir.

The hunter becomes the hunted.

The butterflyfish is too quick and leaps out of danger.

The floods gradually drain back into the established waterways

that run through the forest like blood vessels.

These is so much water flowing through the forest

that even little rivulets can carve out the soil around an ancient boulder.

This is the home of one forest creature,

that has lived here in the Congo for 44 million years.

Picathartes.

These birds mate for life,

and the male reaffirms the bond by displaying to the female.

They're building a mud nest on the underside of the boulder's overhang,

where it'll be protected from the rain.

The female takes the lead.

The male doesn't seem quite so skilful.

Oh dear.

Luckily she can put things right.

Now she's collecting the soft furnishings.

He's brought some too, but he still can't get it right.

In the end, the female seems satisfied with the finish and just in time.

It might look as if he has been banished into the rain,

but in fact they're a great team.

They share the incubation.

Twelve hours on, twelve hours off, for the next three weeks.

In due course, there are mouths to feed, and now the male must prove his worth.

Worms are a good start and he's doing well.

But the chicks are insatiable.

Fortunately, other things are on the menu.

He might be a poor nest builder,

but he is redeeming himself now.

Domestic bliss!

Rocky overhangs are the only place where picathartes will build their nest.

So they owe their home to the stream,

that revealed the flank of the giant boulder.

This stream and countless others like it

merge to form the great rivers

of Central Africa.

(BIRDS CHIRPING)

More than 450 billion litres of rainwater,

travelling down thousands of rivers,

are heading west.

The waters pick up speed

as the rivers spill over the edge of the central plateau

and create giant cascades of white water.

The Kongou forces its way through the wildest,

most untouched forest in the whole of Africa.

The Congo River system drains an area the size of India,

carrying the waters westwards towards the Atlantic.

But before it reaches the coast,

the rivers broaden,

forcing back the forest.

And here, for the first time, there is space.

Wide, flat and safe.

(CHIRPING)

These stretches of sand attract visitors from the coast.

Skimmers, searching for somewhere safe to settle.

(CHIRPING)

The lower mandible of their beaks is greatly elongated.

They slice it through the surface of the water at 10 metres a second.

If and when it hits a tiny fish, it'll snap shut.

But why come up river to these open sand flats?

- (CHIRPING) - This is the answer.

But this nursery will not exist for long.

Four weeks from now it'll be under 10 metres of water.

If by then these chicks can't fly,

- they will drown. - (CHIRPING)

The problem for young skimmers is that when they hatch

the lower part of their beaks is the same size as the upper.

While they wait for it to grow, they do their best

to learn the skimming technique.

(THUNDER RUMBLING)

Open spaces may be safe,

but they give no protection against the driving rain.

These storms are a warning that the skimmers must soon leave.

The river is already rising.

This year, the chicks get away in time.

It's not just water that has the power to clear a way through the forest.

There are animals that could do that too.

They have created a network of pathways

that criss-cross the lowland forest

and run for thousands of miles in all directions.

These path-makers are surprisingly stealthy.

But as night falls, there's a chance of catching a glimpse of them.

(ELEPHANTS TRUMPETING)

(RUSTLING)

Forest elephants are very social creatures,

but in dense jungle it's hard for them to find one another.

These elephants are lucky.

Here in the Congo, there is one special place

where they can meet and mingle.

A place that the elephants have created for themselves.

And this is it.

(TRUMPETING)

Dzanga Bai,

the legendary "village of elephants".

As well as being a place

where they can enjoy one another's company,

this great clearing satisfies another craving.

For salts.

(TRUMPETING)

The salts lie deep under the mud.

So the elephants have got to mine for them,

which they do with high pressure water jets from their trunks.

(WATER BUBBLING)

(ELEPHANTS TRUMPETING)

The precious salts and the chance to socialise

bring in elephants from far and wide.

If an elephant is in the mood to mate, this is the place to be.

(TRUMPETING)

This young bull is in a state of musth,

a kind of sexual fury.

(TRUMPETING)

(TRUMPETING)

He is so pumped up by hormones and the excitements of the crowd

that he seems to have taken leave of his senses.

(TRUMPETING)

(TRUMPETING)

But will throwing his weight about impress the females?

(TRUMPETING)

The cows only become fertile once every two years.

So opportunities to encounter one at the right time are not common.

This could well be the first chance this young male has had.

- (TRUMPETING) - He's lucky.

And there are no older bulls around to put him in his place.

Just for a moment, he is king of the Bai.

(TRUMPETING)

- But his rule doesn't last for long. - (TRUMPETING)

Enter another lusty bull.

- (TRUMPETING) - And a much bigger one.

(TRUMPETING)

But the young bull is still charged up with testosterone.

Bold or foolish, he's going into battle.

He never really had a chance.

(TRUMPETING)

(TRUMPETING)

Dzanga Bai is a huge clearing,

but it's still just a speck in this vast expanse of green.

Elephants might fell trees and carve pathways,

but nothing natural can hold back this forest forever.

Nothing but the Atlantic Ocean.

Loango beach, on Africa's west coast,

one of the last truly wild places

where the Congo jungle meets the sea.

Here the forest gives way to sand, surf,

and fresh sea air.

The cool breezes and warm sunlight

entice creatures out of the dark forest.

(LOWING)

- Forest buffalo appear first. - (LOWING)

And here in the surf, there are hippos.

(SNORTING)

Spray blows in from the sea,

making the grass salty.

So, here elephants can get their tasty salt

without having to dig for it.

This mother with her tiny baby can feel the sun on her back.

Here it's safe for her little one.

They are free to eat in peace.

The bulls have all the room they need, so there is less risk of a fight.

(CHIRPING)

Everyone, from gorillas to forest hogs,

ventures out to relax on the beach.

(SNORTING)

But the forest creatures can't stay out here forever.

Despite everything,

the intense competition, the threats, the darkness,

they need their forest,

just as their forest needs them.

(TRUMPETING)

The Congo rainforest,

a four-day journey to the heart of Africa.

Once the plane leaves, you're on your own.

This expedition planned to film two of the Congo's best-kept secrets.

But to even find them

the crew would have to work very hard indeed.

You might as well be on a different planet

coming to a place like this. Planet Congo.

JAMES ALDRED: Mysterious.

Difficult.

Complex.

Challenging.

You know, everything's trying to bite you.

- Suck your blood. - (BUZZING)

It's like being tickled by a million feathers at the same time.

(SIGHS)

ATTENBOROUGH: The insects might be torture,

but that's the least of their worries.

The only way to get deep into the jungle

is to follow these trails.

Trails made by dangerous forest elephants.

ALDRED: Well, the first thing you need to know about the forest elephants

is you don't want to meet one.

'Cause running away can elicit a charge

and it could be exactly the wrong thing to do.

ATTENBOROUGH: Our team are completely dependent

on their B'aka guides for safety.

(WHISPERS IN NATIVE LANGUAGE) It's moved off now. It's gone? Yes

ATTENBOROUGH: But it's these same forest elephants

that James has come to film

and just to make the challenge harder

he's here to film them in the dark.

Nobody knows exactly what they get up to at night.

They haven't been filmed like this before.

(ELEPHANT TRUMPETING)

I couldn't rig this place if the B'aka weren't here.

Watching my back, really.

James needs to operate the remote cameras

from somewhere out of the elephants' reach.

(WHIZZING)

A tree platform seems like the best option.

(SPEAKING IN NATIVE LANGUAGE) It's not high enough. Uh huh.

Apparently, they have very big elephants round here.

They want us to put it a bit higher, so I think I'll do what they say.

But no one wants to stay out at night and help James with the filming.

(SPEAKING IN NATIVE LANGUAGE) Usually B'aka stay up in the trees only if they are very lost.

(SPEAKING IN NATIVE LANGUAGE) Very dangerous!

So James will be alone until morning.

If anything goes wrong, he's on his own.

If they really wanted to, they could push these trees over.

I can't imagine that's going to be an issue.

As James settled down for the night,

he's got no idea of the trouble that's coming his way.

(ANIMAL ROARING)

What's going on?

Twenty miles away Mark MacEwan is also up in the middle of the night.

The animal he's after is proving impossible to find.

Oh!

So, we get up in the darkness

and we walk through the jungle at night,

hoping to hear the sound of cracking branches

or leaves moving up in the trees.

ATTENBOROUGH: That means chimpanzees are stirring in the treetops

and Mark is here to film chimps hunting for honey.

There's one chimp in particular he needs to find,

a teenager with a very sweet tooth,

known to go further in the pursuit of the bees' nest than any other.

I've spent six days

walking probably the equivalent of a half marathon every day

in 100 percent humidity and about 95 degrees in the shade.

And we just can't find our chimpanzee.

(BEES BUZZING)

ATTENBOROUGH: Time is ticking away

and Mark is running out of filming days.

MARK MACEWAN: At the moment I just need some good luck.

We've come an awfully long way to get this sequence.

We've got probably 10 to 12 days left.

But it's hard work at the moment.

ATTENBOROUGH: All Mark can do is persevere

and hope for a break.

But not all the forest creatures are so shy.

Perched high in his tree,

James Aldred is waiting patiently for the elephants to come in.

(ELEPHANTS SNORTING)

At last the elephants are here.

But they're behaving strangely.

(ELEPHANTS GRUNTING)

(WHISPERS) He knows something's not quite right.

(TRUMPETING)

ATTENBOROUGH: The elephants seem agitated.

(SHUFFLING OF LEAVES)

(TWIGS BREAKING)

ALDRED: They just want to get rid of you.

ATTENBOROUGH: One begins to thump the tree with its head.

James has no option but to weather the attack.

(CRACKING)

ALDRED: Let's lean forward

and keep head-butting, keep head-butting, keep head-butting.

(RUSTLING)

ATTENBOROUGH: Suddenly the cameras cut out.

And James is left in complete darkness.

After three weeks searching,

Mark has lost nearly two stone in weight

but he hasn't given up.

He can't afford to put down his camera for a second.

Suddenly, the guide spots the honey hunter.

This is it.

- (WHISPERS) Where is she? - She's inside the tree.

Just for some honey, she's risking her life. It's amazing.

Well, I think, I just couldn't stop smiling

for several days after filming that. The relief was just unbelievable.

Back at the camera platform, James has had a long night.

For over four hours

the elephant tried to shake him out of the tree.

Got down this morning when the B'aka came to collect me.

Went to look at the camera and he'd pulled it out of the tree

and he'd chewed through the power cable.

He must have gotten a bit of a shock. I mean only 12 volts.

But serves him right, quite honestly.

But at least we got a shot of him before he trashed the camera.

(LAUGHS) Silver lining.

ATTENBOROUGH: Despite this bumpy start,

the elephants soon got used to James

and James got used to the elephants.

Filming here was never going to be easy.

But we were soon able to reveal the night life of forest elephants

like never before.

(TRUMPETING)