In the heart of Southeast Asia
is an ancient kingdom...
with over 3,000 km of coastline.
But beyond its golden shores...
there are secret worlds.
Home to mysterious creatures...
and forest giants.
This is a fast-changing country...
where East and West collide.
People and animals must work together to survive.
Forming unique relationships.
A spiritual land...
full of magic and wonder.
This is Thailand.
Thailand's north is a wild and rugged land.
Cloaked in forest, hiding ancient communities
and unexpected partnerships.
Here, in the jungles of Phu Kao, live some unusual primates.
Phayre's leaf monkeys.
They live up to their name,
eating the leaves of around 100 different types of plant.
But this low-calorie diet means they've got to eat a lot.
So, they need to keep moving.
In all the hurry, youngsters risk getting lost among the greenery.
But babies are born bright orange,
making them easier for parents to spot.
When he's a few months old,
this baby will turn grey, like his parents.
But, for now, he remains highly visible.
Sisters and aunts share in the childcare.
It helps them practise their parenting skills.
But this new mother seems reluctant to release her infant.
Being this protective doesn't allow her much time to rest.
She's yet to learn the benefits of sharing.
On the move again.
It's hard work travelling in the tree tops with a baby in your arms.
Feeding is more difficult, too.
This mother is tired and hungry.
And with others keen to care for her baby...
she accepts their help.
Now, she can concentrate on the important task
of eating more leaves, knowing her baby is in safe hands.
In this remote region of Thailand,
strong partnerships have long formed an essential part of life.
Northern Thailand is a diverse landscape.
Almost two-thirds of it is dominated by forested mountains.
This green veil hides some of the world's rarest creatures.
Like the leopard...
the Malayan tapir...
and the binturong.
Isolation has also protected ancient communities,
where people and nature forge surprising alliances.
Thailand's northern mountains began to form 50 million years ago,
when Indian and Eurasian plates collided...
and the highest peak was born.
Doi Inthanon is known as "The Roof of Thailand".
It stands over 2,500 metres high.
Temperatures here drop to near freezing,
bathing the morning forest in cool, moist air.
Beneath this sea of mist lies an enchanting world
of wild woods and white-water streams.
As water flows through this forest,
it absorbs carbon dioxide from the soil and air,
making it more acidic.
It eats away at the limestone rock of the mountains,
creating worlds within worlds.
Over millions of years,
streams and rivers have carved a maze of caverns.
So far, more than 4,000 have been discovered.
Tham Lod Cave is 50 metres tall.
Thousands of Cook's swifts nest in its cathedral-like vaults.
But they can't nest in peace.
A predator prowls these walls.
This cave racer snake is two metres long,
helping it bridge gaps to scale this cavern.
To escape the snake,
the swifts build their nests in the most inaccessible places.
At night, they keep dead still, hoping the danger passes.
When dawn breaks over the mountains,
the swifts can once more take to the safety of the air.
As they leave the cave, their droppings rain down.
Insect remains in the guano may be appealing to the carp,
but others also take advantage of this fertile sprinkling.
Anpa visits the cave most days.
In Buddhism, heavenly favour can be earned
by small acts of respect or kindness known as "making merit".
Anpa's ritual of collecting this guano also has earthly benefits.
This natural alliance reaffirms Anpa's spiritual beliefs,
as well as providing valuable nitrogen
and phosphorus for the soil.
Traditional small-scale farming in the mountains
requires a close connection with nature.
So, too, does modern-day practice.
In north-eastern Thailand,
where there was once forest,
there is now farmland.
And people here still maintain
an important relationship with wildlife.
Mr Tanon is on a personal mission.
By bending and breaking the spines of banana palm leaves,
he creates new homes for a rare and secretive mammal.
Among these dry, dead leaves,
lives the painted bat.
Painted bats have adopted this unusual roosting site...
because there's a short supply of natural forest in this region.
These bats were a rare sight.
But 16 years ago, a breeding population was rediscovered here.
It's easy to see why they are known locally as "Khangkhaw phiseux",
the "butterfly bat".
For Mr Tanon, the reward for this partnership
is simply to see the natural beauty of these bats on the wing.
Sometimes, all it takes is one person to make a difference.
In northern Thailand,
the lives of animals and people are deeply entwined
and the natural world is an integral part of religion.
Under the full moon, there's one event that happens each year,
symbolising the letting go of past problems
and welcoming new hope for the future.
In Buddhist culture, sky-borne lanterns
represent a move away from darkness into the light.
The festivals of Yi Peng and Loy Krathong
bring families and friends together.
Celebrating the elements of nature,
they honour Phra Mae Khongkha, the water goddess.
"Loy", in Thai, means "to float",
and small baskets, or "krathongs", fill the village river.
These elaborate rituals help communities to live in harmony
and show respect for the natural world.
The connection between people and nature is a complex one.
And there's one creature with which the people of northern Thailand
have had an enduring relationship.
But it has not always been a happy one.
The Asian elephant.
These giants can weigh up to five tonnes.
So, you don't want to cross paths with one in thick jungle.
But this is an elephant this woman knows well.
She was rescued by Lek from a life of toil and hardship.
The felling of the forests for hardwood timber
was once common in northern Thailand,
and elephants were used as tractors.
When logging was made illegal in 1989,
many elephants were forced to earn their keep in the tourist industry.
Now, Lek is working to change the lives
of Thailand's domesticated elephants.
She's rescuing them from illegal logging sites,
circuses and trekking camps, and giving them a new life.
Caboo suffered an injury in a logging camp
when she was two years old.
But she had to carry on working for another 23 years,
until Lek came to her rescue.
The elephants roam here without chains, meeting others,
and forging new bonds.
Lek's sanctuary also enables visitors to meet these giants.
In the wild, Asian elephants live in family groups of related females.
But these individuals have welcomed Lek to be part of their herd.
Elephants are highly intelligent and emotional animals.
And after years of psychological trauma,
these individuals are now putting their trust in Lek.
In Thailand, there isn't always the space
to release large numbers of them back into the wild.
So, these elephants are likely to spend the rest of their days
in this sanctuary.
With Lek's love and dedication, they'll get the care they need,
and now have a second chance at life.
In Thailand's northern mountains,
there are a few places where great tracts of forest still remain.
Especially on the border with Myanmar.
It's the largest area of protected land in mainland Southeast Asia.
At its heart, the wilderness of Huai Kha Khaeng,
is home to some of Thailand's rarest and most elusive creatures...
such as banteng.
They normally live deep within the forest,
but, during the dry season,
come out into the clearings to feed on the last remaining grasses.
These wild cows are believed to be the ancestors
of all cattle in Southeast Asia.
Each herd is comprised of a male, several females,
and their playful calves.
Huai Kha Khaeng is one of the few places
where numbers seem to be growing.
Sambar deer also like to graze here
and are useful sentinels, alert to the sounds of the forest.
They need to be.
Large predators live here, too.
Armed rangers are here to protect the rarest of them all.
The Indochinese tiger.
It is estimated there are only 200 of these tigers left in Thailand.
And they face extinction
due to habitat loss and poaching.
The rangers pass on any information they find to scientists...
who are also working hard to prevent the tigers' decline.
It's a great collaboration between the Department of National Parks'
Wildlife And Plant Conservation and the Wildlife Conservation Society.
But it's tough work for everyone.
Tigers are almost impossible to find.
The best way for Som Pot and the tiger research team
to work out how many live here is by using camera traps.
They've revealed that here in Huai Kha Khaeng,
just four hours' drive from Bangkok,
there's a significant tiger population.
Many Thai people are unaware these secretive cats
still exist in their country.
To know where to put the camera traps,
the team need to understand the tigers' territory.
To do that, they follow a number of key individuals
using satellite collars.
Today, Som Pot's tracking one particular tiger.
Its satellite collar shows it keeps returning to the same place.
It's a good chance to get vital camera-trap footage.
The tiger has made a kill...
a male sambar deer.
They must work quickly, with minimal disturbance.
Later that night, the tiger returns.
Camera-trap footage has been vital for documenting the tigers here.
Tiger stripe patterns are like fingerprints,
unique to each individual.
The database shows around 70 tigers roamed these forests.
Numbers have almost doubled in a decade
and that's because of people like Som Pot and his team.
Restoring natural harmony in the forests of northern Thailand
is also vital for preserving the spiritual lives
of the people that live here.
These men are from the Black Lahu hill tribe.
Their ancestors lived in the Himalayan foothills
for over 2,000 years, settling here within the last century.
They believe spirits dwell in this forest.
For Papa, cooperating with them is vital.
The Black Lahu have a unique relationship with nature,
with an animist faith that predates Buddhism.
This tree will become a bridge to the spirit world.
An offering is made.
Papa believes this cord will pull his wife's lost soul
along the tree trunk back from the forest.
By tying the cord around her wrist,
the spirit doctor reconnects Nalor with her soul.
A Lahu will never cut a spirit cord, wearing it until it falls off.
This sacred connection with the forest is cause for celebration.
By dancing, the Lahu show their joy to their creator spirit, Gui Sha.
The Lahus' spiritual relationship with the forest
protects their loved ones and strengthens the community.
These remote mountain worlds
not only hide ancient traditions, they also hide age-old showdowns.
Up here lurks one of northern Thailand's
more surprising creatures.
The big-headed turtle.
As his name suggests, he has an enormous head,
with super-sized jaws.
Food can be hard to come by in this fast-moving water,
but as he only needs to eat every few days, there's no real urgency.
And he knows where he's going.
Long claws and a muscular tail propel him upstream.
He's a little on the slow side, but it helps him save energy.
He's got to where he wants to be.
It's now a waiting game.
Other ancient creatures are drawn from the forest to the water.
Freshwater crabs.
It's likely their ancestors ended up here,
300 km from the coast,
when the mountains formed millions of years ago.
To a crab, the big-headed turtle looks much like a rock...
and that's just what he wants.
Now those jaws make sense.
The ideal crab cracker.
Over millennia, remote forest streams
have brought these unlikely animals together.
Thailand's mountainous north is an ancient land...
but there are places where people have had a big influence
in recent years.
Like here, in the hills of Mae Hong Son.
Commercial logging cleared parts of this land,
creating new opportunities for other kinds of plant.
Sunflowers now carpet these mountains.
They were first brought to Thailand from Central America
as garden plants about 70 years ago.
But no-one quite knows how they got to these slopes.
Up here, they spread like wildfire.
Many tourists come to admire the spectacle.
The people of the North have embraced this interloper...
adopting it as a provincial mascot.
The Mexican sunflower is now part of the fabric of northern Thailand.
Where farmland is replacing forest,
wildlife finds new ways to flourish.
Weaver ants have colonised much of this man-made landscape.
Hundreds of them work as a team to build their home out of leaves,
protecting them against the elements.
To lash the leaves together,
gangs of workers pull as one.
Bridges are built, helping ants move quickly around the site.
To hold their construction together,
they rely on the youngest members of the colony:
grubs.
When they're in their final stages of development,
they produce strands of silk...
and make the perfect glue gun.
In just a few hours, their new home is complete.
Their nest happens to be on a mango farm...
but it's no ordinary orchard.
Mr Bunchu has recruited this army of miniature warriors
to defend his fruit.
They'll eat any pests.
And by tying these strings between mango trees,
Mr Bunchu helps the ants get to new foraging grounds,
expanding their empire and protecting his orchard.
Healthy ant colonies mean fewer pesticides
and the weaver ants give the farmer something else.
Mr Bunchu likes to harvest their eggs.
He takes only a little from each nest,
separating the ants so they can return to the colony.
These eggs are a Thai delicacy...
and a favourite dish of the North.
By working with wildlife, farmers in northern Thailand
are able to benefit from nature's bounty, and help it flourish.
But the greatest rewards of all
are found in the shadows of these northern mountains.
The soil here is watered by rivers that flow down through this land,
irrigating the rice fields.
Thailand exports more than nine million tonnes of rice a year.
Every rice plant is vital for Mr Thipuin's crop...
but there's constant threat.
White-backed plant hoppers invade the paddy fields.
They suck the sap and stunt the growth of the rice plants,
reducing the yield.
But living beneath these mountains,
the farmers have their own natural pest control.
Every evening, it stirs.
300,000 wrinkle-lipped bats emerge
to hunt for insects on the wing.
This living ribbon of bats is a welcome sight for the farmers.
It's estimated that, by eating white-backed plant hoppers,
these bats rescue enough rice
to feed 26,000 people in Thailand each year.
And by planting his rice in the flight path,
Mr Thipuin will benefit from these hungry little helpers.
In these northern mountains, success and survival
rely on working together
and exploiting opportunities when they arise.
Ancient beliefs, modern ideas,
and unexpected alliances
all help to maintain the natural harmony.
The toughest challenge for the northern Thailand team
was filming Indochinese tigers.
There are only about 350 left in the wild.
The only place they stood any chance of success
was in the forest of Huai Kha Khaeng Wildlife Sanctuary.
Producer James Hemming teamed up with the scientists
who've devoted their lives
to understanding the habits of these creatures...
sometimes using quite unusual tracking techniques.
Yeah.
Cor, that's really... It's quite potent!
Scent marks define tiger territory.
They're like signposts,
providing vital clues to their whereabouts.
Two different tigers?
Even so, finding them is far from easy.
The team have only got three weeks in this forest,
which is four times the size of Greater London.
James is going to need more than a sniff to succeed.
Wow! Yeah.
Camera traps are his best chance
of getting footage of these elusive animals.
The cameras need to be rigged
at key locations in the forest where they'll be triggered by motion.
And to film a passing tiger,
it's really important to get the frame size right.
Pretty good.
Yeah. It's all good.
Cool. okay.
For the scientists, camera traps have also proved essential.
Not just for research, but in helping police with anti-poaching.
In 2015, camera-trap images proved that a tiger
which once roamed these forests, had been illegally poached.
It led to the prosecution of three men.
The crew aren't relying just on camera traps.
Wildlife cameraman Graham MacFarlane
and guide Kwanchi, are also in the field.
A tiger could be ten metres from you and you wouldn't see it.
This place is covered with animal prints.
There's elephant, loads of deer.
It's a really good sign, all prey for the tiger.
I've got a really good feeling about this place.
And there's a fresh tiger track, just down there.
Great news. Well spotted, Kwanchi!
Graham is using a more traditional method,
waiting it out in a hide near a spring.
So, I've got my camera there, my seat,
my little window out on the world.
As Graham settles in,
the camera traps start to bring in results.
A leopard is caught on camera.
But no sign of tigers.
A few days later, scientist Som Pot may have found the breakthrough
the rotting remains of a tiger kill.
"Come to Thailand!" they said. "Full of beaches!"
The tiger could return at any time,
so the team need to work swiftly.
I really hope this works. It could be the best chance we have
of actually filming a tiger here.
Now all they can do is wait.
Patience is also key for Graham.
Another day in the office.
Still no tiger. I'm not going to give up yet.
As it's the height of the dry season,
the spring is proving to be a busy place.
A Malay tapir. Such an unusual-looking animal.
But this binturong has Graham baffled.
I shall have to look that one up in the... mammals book.
That's is pretty cool, though.
And there are signs that predators may be close.
I just saw one of those barking deers with a massive scar.
I can only imagine it was a... lucky escape.
Possibly from a tiger.
It makes me nervous.
Graham is right to be nervous.
A ranger was recently attacked here by a tiger.
But, right now, there's a far bigger threat that no-one had anticipated.
A forest fire... out of control.
James and the team are forced back to base.
It's weird, because it was quite sunny earlier...
and now with the wind's picked up, and it's so smoky.
The langurs all left at the same time.
They went that way.
So, I guess...
if the fire does come this way, I'll head that way, too.
Graham's time in the hide is over.
Back at the headquarters,
the fires are now dangerously close to James and the team.
It's suddenly become, within, like, ten minutes, incredibly smoky.
We're actually having to evacuate.
Pretty worried, to be honest. It's just so unpredictable.
Okay.
Holy moly!
The team managed to get out safely,
and despite the fires, the camera traps were saved.
Wow!
Look... I mean, look at the size of him.
Fantastic! Wow!
- It's lucky that we got this? Really? - Yes.
- Healthy. Yeah. - Really healthy?
- Good body condition. - Which is great.
That must mean there's plenty of animals to, you know, hunt.
I'm over the moon that we actually managed to,
you know, get the footage. Yeah.
- Thank you very much. It was great. - You're welcome.
Over the course of the last 20 years,
tiger numbers have increased here.
And there is new hope for Thailand's biggest land predator.