Asia has more forest than any other continent.
A trillion trees.
At its heart, in the shadow of the Himalaya,
stand the monsoon jungles of India and Nepal.
They are ruled by the biggest of all cats.
The Bengal tiger.
Asia's forests are full of life.
For the animals that live here...
..they provide a multitude of opportunities.
Nepal.
Forests cover almost half the country.
It's the dry season.
Between the trees, meadows of elephant grass
provide cover...
..for the most intimate of behaviours.
TIGER RUMBLES
In the last ten years,
the number of tigers in Nepal has doubled.
TIGERS SNARL
There are so many here that, remarkably,
pairs are mating within just 100 metres of each other.
TIGERS SNARL
Males play no part in raising their young.
This mother has three almost fully-grown cubs.
The largest, a male,
is becoming increasingly restless.
His favourite playmate is his brother.
His sister is less sociable.
He is two years old
and beginning to explore by himself more frequently.
He must keep his claws sharp.
Prey is never far away.
But to catch a hog deer,
he must get within pouncing distance -
undetected.
DEER CHIRP
Blown it.
Tigers visit the river frequently to cool off.
He tests the water.
Just right.
His siblings are also here.
But afternoon baths are not going to get any of these tigers a meal.
It's their mother who must provide.
And there are good opportunities
on the other side of the river.
No matter how experienced tigers are,
most of their hunts end in failure.
But they can stalk for hours on end,
hunting relentlessly.
Spotted chital deer are constantly alert.
Their fawns are extremely vulnerable.
DEER YELPS
This will keep her going as she continues to hunt.
Not everybody's been so successful, though.
But Asia's monsoon forests are so rich,
this family should continue to flourish.
200 miles to the east lives a beast
so big that even a tiger rarely dares to attack it.
The greater one-horned rhinoceros.
They weigh over two tonnes
and have skin an inch thick.
They eat mostly grass and reeds.
There are ponds here filled with water lilies...
..where the females regularly bring their young.
The males compete for access to the females.
RHINO BELLOWS
Sometimes, the best move is to retreat.
Elsewhere...
..younger rhinos are engaged in other business.
Flirting.
RHINOS GRUNT
Their courtship is an elaborate game.
A kind of kiss and chase.
He's caught her.
But when you're lacking in experience,
consummating the relationship is not easy.
After all the excitement,
the forest also offers relaxation.
A long, leisurely mud bath.
As the dry season continues,
small ponds like these become increasingly popular.
But a change is coming.
The rains of the monsoon.
They fall most intensely in southern India.
In the forests of Kerala,
huge storms unleash billions of cubic metres of water.
And that triggers the appearance of one of the strangest
of all Asian creatures.
It spends most of its life up to eight metres underground.
CROAKING
But just once a year, it emerges
to breed.
A purple frog.
This female has a belly full of eggs.
And on her back, a newly acquired male partner.
He grips her spine,
making deep indentations in her flesh.
They have timed their emergence to coincide with the monsoon rains.
Somehow, in the darkness,
they must find a stream in which to lay their eggs -
and then get back underground before dawn.
But during the monsoon,
a torrent can develop in minutes.
The best breeding spots are upstream.
There's nothing for it but to take the plunge.
Using her limbs like grappling hooks,
she hauls them both up the rocks.
At last, shelter!
An excellent place to lay eggs.
And the male can fertilise them.
They can develop here without getting washed away.
Having given their brood the best chance of success,
they return underground for another 12 months.
What they do there, nobody knows.
To the southeast of India's monsoon forests,
across the Indian Ocean,
lie the continent's most diverse and spectacular jungles.
The tropical rainforests of Southeast Asia.
They are among the oldest such forests on Earth.
Here, on the island of Borneo, live orangutan.
They spend most of their time foraging for food.
But this female also has something else on her mind.
She is looking for a partner.
Finding a suitable one should be easy.
Dominant male orangutan in Borneo have huge cheek pads.
This one would be quite a catch.
Normally, it's the males who pursue the females.
But sometimes, a female may have to take the initiative.
This sort of behaviour is very seldom seen.
But the feeling does not seem to be mutual.
Never mind, there's plenty more swingers in the trees.
This one has a higher rank...
..so he is an even more desirable mate.
An orangutan with an appetite like this should be strong.
If only he had eyes for her, too.
Oh, well.
The search continues.
This male hasn't yet developed cheek pads.
But looks aren't everything.
He seems keen on sticking around.
Could he be the one?
The two of them are soon inseparable.
Even going so far as moving in together.
Sharing a nest.
It's not long before she's showing.
Orangutan pregnancies last the same length of time as human ones.
At last.
Her son.
Just ten days old.
For the next eight years,
she will devote her time to teaching him
how to live and find food in the forest.
And for the time being, at least,
her search for a mate is over.
Orangutan babies spend almost all their time
high in the canopy.
But other young animals never leave the rainforest floor.
Almost hidden amongst these trees
are the world's smallest elephants.
A few months old,
this Bornean elephant calf is only about the height
of a very large dog.
Guided by his mother, he must follow the herd wherever they go.
Elephants have excellent memories.
Matriarchs retain a mental map of different landmarks.
Some more challenging than others.
There are threats here.
But crocodiles are not the biggest danger.
The river is over 100 metres wide.
And the current is so strong it could easily carry a calf away.
His mother and aunts surround him.
Supporting him with their trunks.
He is exhausted.
His mother has brought them here for a particular reason.
She knows food is nearby.
The source is one of ours.
Oil palms.
Elephants greatly enjoy their fruit.
The plantation owners do their best to protect their crop.
Electric fences are everywhere.
The elephants have become trespassers
on their own land.
They know, however,
how to deal with such feeble defences.
ELEPHANTS TRUMPET
This is an unpredictable world.
Plantations are frequently completely cut down,
so that new trees can be planted.
Now it seems there is nothing to eat here.
But what looks like desolation...
..is actually opportunity.
This plantation is different.
Here, the elephants are welcome.
When old trees are felled, the herd can provide
a waste-disposal service.
As a result, some Malaysian farmers
have started to encourage elephants onto their land.
With so much food...
..youngsters have plenty of get-up and go.
And this place has other attractions, too.
CALF SQUEALS
In some areas of Southeast Asia,
rainforests have been selectively felled,
if not totally destroyed.
But in others, they remain extremely diverse.
To the west of Borneo
lies the island of Sumatra.
This is the home of one of the most extraordinary of plants.
It's the biggest of its kind.
The titan arum.
Up to three metres tall,
it has taken ten years to mature.
But now it has just two days in which to reproduce.
As dusk descends,
others are opening simultaneously
across the forest.
As the air cools...
..the plant does the opposite.
Using ten years' worth of stored energy,
the titan arum warms.
It starts to release the stench of rotting meat.
The smell drifts through the forest,
attracting visitors.
A carrion beetle.
The arum has deceived the beetle
into thinking it has discovered a dead animal.
The insect is now trapped.
The walls are too slippery to climb back up.
And now it's surrounded by hundreds of male and female flowers.
It can use the female ones like a ladder.
Above them, however,
are the tightly packed male flowers
that lead to an overhang on which there's nothing to grip.
But the arum is not about to eat its prisoner.
It needs it to remain alive.
As the night continues,
a transformation takes place.
The male flowers start to release pollen.
Microscopic granules coat the unwitting beetle.
With the sticky substance providing foot holds...
..the overhang is no longer an obstacle.
And the beetle flies away...
..to visit other arums...
..and so spread the pollen...
..completing the flower's life cycle.
The rainforests of Southeast Asia are extremely diverse.
But to the west,
on the very edge of the continent,
where conditions are very tough indeed,
there are forests with perhaps even greater surprises.
This is a country seldom associated with woodlands.
Iraq.
But in one special corner...
..lies the region of Kurdistan.
Here grow dense groves of oak and pistachio trees.
And they contain a truly rich variety of life.
There are predators here.
The Asiatic wildcat.
And the shy striped hyena.
But there is also another carnivore,
and one that is hardly ever seen.
A Persian leopard.
There are perhaps no more than two dozen individuals
in the whole country.
Their survival is precarious.
A lone male cautiously patrols his territory.
Then, a female.
These are the first images ever taken
of a female Persian leopard in Iraq.
She is even more secretive than the male.
Several months might pass before she comes back to this spot.
But finally...
..she reappears.
And at her side,
a new family.
The cubs are very young
and follow her everywhere.
And if she can keep them safe,
there is a chance that this tiny population
could establish itself in these precious upland forests.
High-altitude forests can be found right across Asia,
from Arabia all the way to its easternmost reaches.
In Southern China grow some of the most extraordinary.
Here, more than 500 species of tree
grow on top of immense rocky pillars.
Tree roots force rocks apart...
..hastening erosion and creating new pillars...
..in these gardens in the clouds.
These east Asian forests are also home
to an army of strange creatures.
Here, in nearby Taiwan,
these are the grubs of the yellow-legged hornet.
This insect has a truly fearsome reputation.
Its sting causes excruciating pain.
And, in rare cases, even death.
The grubs must fatten up if they are to become adults.
GRUBS SCRATCH
They scrape the sides of their hexagonal cells...
..singing for their supper.
A call to worker hornets.
The workers must constantly feed the grubs
with protein of some kind.
This is a crucial task,
because amongst them are the queens of future colonies.
Raiding parties head into the jungle.
They're seeking prey -
wild forest bees.
They are only half the size of a hornet...
..and they defend their home by waving
their abdomens rhythmically,
in an attempt to confuse predators.
But the hornets don't plan to invade the nest.
Like goalkeepers,
they aim to catch the bees in mid-air.
Clutching its victim, the worker returns.
A meatball of chewed bee.
The protein-packed meal for the grubs.
Other hornets work as builders...
..making wood pulp
and building hundreds more cells every day.
Their hunger satisfied...
..the grubs spin silk cocoons...
..and enter the final stage of their transformation.
But the entombed grubs are vulnerable.
BUZZARD CRIES
Nests are not immune to attack.
Honey buzzards.
These raptors have a particular liking for immature hornets.
The workers fight back.
But the bird's feathers interlock,
forming a sting-proof shield.
The nest is destroyed.
But deep within the ruins is a new queen.
With a handful of remaining troops...
..she will soon rebuild an army.
In the mountains in China,
seasonal forests hide Asia's most beloved bear.
PANDA HONKS
The giant panda.
This four-month-old cub has a lot to learn.
Escaping her mother's attention isn't always easy.
But pandas spend virtually all their waking hours
feeding on bamboo...
..so her cub is left free to explore.
One of the cub's main concerns is learning to climb.
In this reserve, pandas are being bred to return to the wild.
Several older ones seem to have mastered
the skills of climbing in the tree tops.
And the younger one is determined not to be left behind.
The first stage is to get a good grip.
PANDA BARKS
Nobody likes parental interference.
Even so, a bit of encouragement goes a long way.
That is a whole 20 centimetres off the ground.
What a shame that nobody's watching.
It's tiring work...
..and time for a cuddle with mum.
Asia's animals thrive
in its extraordinarily diverse jungles.
They adapt and grow using the trees to their advantage.
And if we can protect them...
..the forests of this continent
could give them a home long into the future.
For the Jungles team,
filming the Persian leopard would mean
an expedition to the remote region of Kurdistan
in northern Iraq.
Prior to filming, only a handful of shots
existed of leopards here.
To find them, the crew join conservation biologist
Hana Raza, who first discovered the leopards.
When you meet people,
and the second they find out that you're from Iraq,
there's this shock.
"How could that be? Iraq is only deserts and war!"
They can't actually imagine that there's so many amazing,
rare, elusive animals.
The forests here hold an astonishing diversity of species.
Even Eurasian wolves.
But filming in this environment is no easy feat.
One of the biggest challenges is the landscape.
The forests where leopards are thought to roam...
..are on steep mountainsides.
What's more...
..large areas of the country are still off-limits
due to minefields.
Despite efforts to clear them,
millions remain in the soil,
decades after conflict.
Just walking along in single file now.
And we're walking in single file because we're walking
right along the edge of a minefield.
Our guides know where the path is,
so as long as we follow them...
..we're safe.
Although staying safe does mean keeping close
to the cliff edge.
Brothers Nabaz and Bahez Horeny
have spent years following the wildlife
between the minefields.
Hana, the brothers and the crew
set up a network of camera traps.
Over the previous decade,
the only sightings had been of male Persian leopards passing through.
Expectations are understandably low.
UNTRANSLATED
Yet footage starts to come in.
Ah! LAUGHTER
There are several males -
but one appears frequently,
suggesting he's dominant here.
His scent-marking behaviour indicates
there might be a female in the area.
So the crew intensify their efforts.
And the reward...
..is a truly rare glimpse.
It's a beautiful shot, to be honest.
HANA LAUGHS
These images are a huge moment for the team.
It's been 12 years camera trapping leopards.
All of them have been males.
But this is the first female.
Which is amazing!
Absolutely amazing.
What's more, this female's belly suggests she might be pregnant.
Fingers crossed our next shot will be with cubs.
But unfortunately,
the summer passes with lots of camera trapping...
..and no sign of the female.
The male, however, is not so shy.
It's not for another three months
that the female eventually reappears on camera.
This time, they notice a change.
Now it's just very skinny
and very different from that stage it was in that month.
So they are suggesting that
it might have given birth.
The crew reason that, if she has cubs,
she'll be hiding them away.
All they can do is wait and hope.
And in time, their patience pays off.
The brothers film the first leopard cubs
ever recorded here... THEY LAUGH
UNTRANSLATED
..and get to tell Hana about it.
THEY LAUGH
And a whole year after the crew started...
..the brothers get a very special sighting of the female,
recorded on their own cameras,
teaching her cubs to hunt.
The first time I captured the Persian leopard,
not in a million years did I think that I would be looking at,
like, an amazing shot of a family of Persian leopards - no.
It's amazing!
Finding the cubs again shows great hope for the future
of these magnificent cats
in these remarkable Asian forests.
Next time, the human world...
..where animals have surprising strategies...
..to survive in Asia's most crowded places.