Original subtitles

Now home to nearly eight billion people,

and yet there's still places that remain pristine.

Where a spellbinding variety of life continues to thrive.

These are the last regions that could be called Eden.

In the heart of Southeast Asia,

lies the tropical island of Borneo.

Around the size of Texas,

its ancient forest has remained unchanged

for 140 million years.

Bathed in sunshine

and quenched by abundant rainfall

over time, these hothouse conditions

have spawned some 60,000 species of plants and animals.

Making Borneo, possibly, more biodiverse

than any other island.

Evolving in isolation

over 6000 of its inhabitants

are found nowhere else on Earth.

Remarkably, this wealth

Is built on a foundation of shallow, nutrient poor soil,

and yet, somehow, life has triumphed...

turning this into a paradise

unlike any other.

Dawn breaks over Borneo's flooded lowland forest...

a mosaic of tree-lined waterways and swampy thickets.

A unique habitat that has given rise to a one-of-a kind primate.

Proboscis monkeys,

named after their outstanding noses.

For an alpha male, the bigger the nose,

the bigger the harem.

They live in groups of 20 or more.

This two-year-old female is no longer dependent on her mother,

but still needs the protection of her tight-knit family.

They survive mainly on a diet of leaves that are low in calories

and difficult to digest.

Unless you have a barrel belly

and 48 hours to ferment them.

Young leaves aren't as tough,

but there are fewer to go around.

And breakfast finishes off their supply.

Now the tenderest shoots

are on the other side of the river...

patrolled by the largest reptiles in the world,

saltwater crocodiles.

Up to six metres long.,

they'll devour any animal they can sink their 10 centimetre teeth into.

But if the monkeys are going to eat,

they'll have to cross.

The alpha male leads the way,

the rest rapidly follow.

The babies must cling onto their mothers.

Each impact carries soundwaves up and down the river.

Now too big to be carried,

for this youngster, a solo plunge is a daunting prospect.

This is a 12 metre leap of faith.

At the surface, she's desperately vulnerable.

But these unique monkeys are semi-aquatic.

With partially webbed hands and feet,

they can propel themselves quickly, but quietly,

covering a distance of up to 18 metres!

Made it.

She joins in the buffet of fresh young leaves.

As females mature, they seek out mates in other groups,

but for now, this family is all she needs.

Close bonds and specialist adaptations

allow proboscis monkeys to prosper in this water world.

Moving inland, Borneo's forest rises to form a towering canopy.

By noon, the first of the daily downpours

tops up the humidity to 100 percent.

With twice as much rain as Florida,

this Eden is a sultry, 30 degree paradise.

Nurturing the tallest tropical trees in the world

that play a crucial part in the combat of climate change,

each of them absorbing more carbon than any others.

And over 30 metres up,

the world's largest tree-living ape,

the orangutan.

A 30-year-old mother

and her three-year-old son

are having a mid-morning snack.

She'll dedicate eight years to rearing him.

Aside from humans, it's the longest infancy of any ape.

Until he's fully weened,

it's vital she gets enough to eat

or her milk will run dry.

But she needs more than low calorie leaves.

Her challenge is to find some energy-rich fruit

and fast.

Arms that span almost two metres

and 35 kilos of body weight

help to bend branches and sway through the canopy.

Still fuelled-up from his morning feed,

her son does a good job keeping up.

But he mustn't put a foot wrong.

A fall from up here would be fatal.

By the time they've covered a couple of kilometres,

his mother needs a pick-me-up.

Leaves and bark offer some sustenance...

and it's an opportunity to teach her son

the 500 or so species of edible plants

that Borneo has to offer.

While his mother takes a power nap,

Nakal lives up to his name.

Malay for "naughty."

For him, life is an adventure,

and this is the ultimate playground.

All mothers know that kids like to push their luck...

sometimes, a little too far.

Around one in ten infants die,

mostly from falls.

Nakal has learnt a valuable lesson.

The other great threat he faces is starvation.

In this rainforest finding fruit is a treasure hunt.

Scattered far and wide, it ripens at different times.

But orangutans build up 3D "mind maps"

that detail not only where to find it,

but when it's good to eat.

Finally, after a morning of travel, fruiting trees.

But they've been overrun by a troop of macaques.

Nakal voices his annoyance.

But he's just a pipsqueak.

They're more nuisance than a threat,

so his mother makes it clear...

"mess with him...

"you mess with me!”

Fruit provides the orangutans

with the calories they crave.

Over Nakal's long childhood,

his mother will pass on the knowledge he needs.

The wisdom of many generations

allows Borneo's orangutans

to enjoy the riches available here.

By early afternoon,

as the tropical sun dries out the forest floor,

legions of plant eating insects home in on anything edible.

Armies of termites emerge...

up to 7000 per meter squared.

Many specialise in consuming trees

from the inside out.

The trees deploy defence systems,

sealing their wounds with healing resin.

But this meranti tree has its very own protection,

assassin bugs.

This four centimetre long female repurposes resin

to weaponize her forelimbs.

Dressed to kill,

she comes to the tree's defence.

There's no escape from the viscous viciousness of this femme fatale.

Once the termite is swaddled in sap,

she skewers it with her stiletto mouthparts...

and slowly syringes out its insides.

With so much prey to tap into,

this tree is the ideal place to raise a family.

A passing male could be the perfect partner.

What follows is completely new to science.

A courtship dance thought to test his tenacity.

If he can't withstand her gluey grip,

they won't stick together.

Hmm. Suitably impressed,

she delicately dabs resin on the tip of her abdomen,

ready to cement their relationship.

The babies, with their menacing mittens,

will spend their entire lives liquidating termites.

There are close to 200,000 species of insect in Borneo.

It's the ideal foraging ground for one of the rarest bears on Earth,

the Bornean sun bear.

Only the panda is more endangered.

His 10 centimetre long claws rip open a termite mound with ease.

Dense fur protects him

from meals that might bite back.

But it's no defence against a reticulated python.

Growing to more than nine metres long,

they have been known to swallow a little bear whole.

Nosing around his forest sanctuary,

pickings are slim.

That's why this bear is so small...

no bigger than a large dog.

But a sense of smell, a 1000 times more refined than ours...

can identify an aroma from 90 metres or more.

And he's caught the merest whiff

of one of the jungles most sought after prizes...

Honey!

But to sniff it out... he'll have to go ape!

Lightweight and agile, he's known as a "monkey bear."

He pinpoints the hive by trial and error.

He's spotted the hive.

Buzzing bees mean golden honey.

Just one last tree to climb to reach the jackpot.

At almost 25 centimetres,

that tongue is longer than any other bears.

Perfect for honey slurping.

Now, that dreamy dessert,

plus drowsy afternoon heat

can only mean one thing...

it's siesta time.

He busies himself making a lofty bed.

Haa... relax.

Mmm, that breeze feels good!

By late afternoon,

gloom gathers at the forest floor.

But even as the light dwindles and photosynthesis fizzles out,

feeding doesn't have to stop.

Borneo's vegetation is ingenious.

Of its 15000 different plant species,

the highest diversity of anywhere on Earth...

one family has turned from strictly vegan...

to meat eating.

Pitcher plants.

One careless step on that slippery lip

and the open mouth is waiting.

Once inside the distended stomach cavity,

there's no escape from death by digestion.

Victims are slowly dissolved in a bath of enzymes.

Some pitchers even exploit warm blooded animals.

Almost 40 centimetres tall this giant pitcher

offers a sugary reward

for a 20 centimetre tree shrew.

One false move and it will fall into the two litre bowl of digestive juices.

But this pitcher is counting on another deposit,

shrew poo,

rich in nutritious nitrogen.

But one pitcher,

nepenthes ampullaria

has gone a step further away from its carnivorous diet

and back to being vegetarian.

But a plant-based diet can be hard to stomach.

So this pitcher recruits help.

It offers mosquito larvae refuge,

in return for stirring the organic soup.

And the pitchers extract all the goodness they need.

Today they are widespread across the Bornean jungle.

In this Eden, plants can be every bit as enterprising as animals.

As the last rays of evening sun light up the treetops,

for another of Borneo's most resourceful residents,

the chore of finding food Is far from over.

Oriental pied hornbills are one of Borneo's largest fruit eating birds.

Weighing in at almost a kilo,

this male...

and his faithful partner

need to eat a third of their bodyweight every day.

Their almost 20 centimetre bills

designed to pick off even the tiniest fruits.

With sunset fast approaching,

they're still hungry.

But these highly intelligent birds

have worked out where to go to

for an evening meal.

Heading to where Borneo's uplands rise from the forest

they perch at the yawning mouth of a vast cavern.

Over thousands of years,

rainwater has eaten away at these limestone crags,

dissolving the rock to form cave networks

that stretch for hundreds of kilometres.

A highly-desirable home for something.

Predators gather.

A Wallace's hawk-eagle arrives in anticipation.

A sigh rises to a scream.

As 300,000 wrinkle-lipped bats

are disgorged from their roost.

A fast-moving feast...

for a perfectly poised cave racer snake.

Armed with eight centimetre long rapier talons,

the hawk eagle is designed for aerial interception...

snatching ten or more bats every evening.

Spurred on, the hornbills launch their aerial assault.

But without the hawk's grasping talons...

it ends in frustration.

Time to consider a tactic better-suited to his hardware.

He repositions as close as possible

to the streaming column of bats.

With binocular vision to judge distance,

and that precision beak...

he needs to time it just right.

He gives the first catch to his partner.

He'll grab a half a dozen more bats,

and they'll be content.

Only now has the full behaviour been caught on camera.

Of all 54 species of hornbill,

the oriental pied has the most diverse diet.

This intelligent bird has learnt to cash in

on every chance that Borneo's varied habitats have to offer.

With their bellies full,

the hornbills retire to their night-time roost.

But there are places in this jungle that never sleep.

Every night, the bats from this one cave

are thought to harvest over two tonnes of insects.

On their return,

their excrement falls like rain...

building, over centuries,

to form a mountain of guano.

More than 15 metres high

and 30 metres long,

it sustains an incomparable ecosystem of tens of thousands

of cockroaches,

and a swarm of other scavengers.

Half metre long centipedes, giant spiders,

even cave crabs.

And fresh meat is highly prized.

But it's the cockroaches that get to the victim first...

stripping it to the bone, within hours.

Borneo's caves have created a unique habitat,

based on growing stockpiles of forest minerals.

Over thousands of years,

the unparalleled diversity of this Eden

has been driven by a lack of nutrients,

thriving on ingenuity

and the daily rhythms of this singular island paradise.

But recent decades have seen rapid changes

that affect all of the forest inhabitants.

Long ago, stories were told of sacred spirits

that inhabit the jungle.

Part man, part animal,

almost a metre and a half tall,

this is a male orangutan.

At 20 years of age, his wide facial "flanges"

are a sign of virility.

But he needs to get clear of the thick undergrowth

to catch the attention of a passing female.

At around 909 kilos,

he's clearly at the upper limit

for a life in the treetops!

Up here, his stage is set.

Male orangs serenade

to draw in prospective partners.

His flanges are thought to project the song,

and with less vegetation to dampen the sound,

it beams almost two kilometres across the forest.

It's known as a "long call.”

Scientific research suggests he's singing his own praises,

extolling health and status.

Who could resist such a performance?

Bad luck, it's a juvenile male.

And that grin is no greeting.

It's a threat.

"Okay, that's the way you want to play it?"

The afternoon rains now threaten the performance.

Undeterred, with his makeshift umbrella...

he continues singin' in the rain.

There's a reason these mournful "long calls” go unanswered.

Wilderness abruptly gives way to oil palm.

In the last two decades,

80 percent of orangutan habitat has been felled.

Paradise has been lost to plantation.

Thousands of these gentle apes are left marooned

in small pockets of rainforest.

Many males may never breed again.

Elsewhere, virgin forest still exists,

and orangutans are protected by parks and sanctuaries.

Borneo's ancient habitats

have been woven together

by millions of intricate relationships...

plant and animal.

As long as we can keep this unique trove

of treasured species safe,

this island's sacred forests

will be forever Eden.