- [Narrator] Yunnan Province, China.
The headwaters of the mighty Mekong River.
The start of a 2,700-mile journey
from the Tibetan Plateau to the South China Sea.
This is a world of extremes,
from snow-capped mountains to lush tropical rain forest.
As the glacier meltwater begins its descent,
the Mekong's story unfolds,
flowing through the most biodiverse region in China,
home to the highest altitude primate in the world,
and a bird that almost defies biology
to fly over its highest peaks.
Rare and endangered creatures struggle to survive
in habitats that are ever shrinking.
Yunnan is our first stop on a breath-taking journey
across some of the most remote locations in Asia.
Following the Mekong through China,
Laos, Thailand, Cambodia, and Vietnam,
as we begin to unravel the mysteries of the Mekong.
(adventurous music)
(peaceful music)
Beginning as a trickle more than
16,000 feet above sea level,
high in the snow covered Mountains of Tibet,
the Mekong River comes to life.
It flows through steep river gorges
of up to 10,000 feet deep,
and is bordered by glaciated peaks over 20,000 feet high.
From its source in Tibet, the Mekong River
enters Yunnan province in southwestern China.
It then precipitously descends over 15,000 feet
before it enters Laos,
coursing through the jungles of Thailand,
the forests and lakes of Cambodia,
and the sprawling delta of Vietnam,
before ending its journey in the South China sea.
Here, in northern Yunnan, it's February,
and in the isolated alpine forests that
winter is coming to an end.
Snow has slowly given way to sunnier days,
though temperatures hover around freezing.
But this inaccessible region boasts a secret.
In a narrow region on the Tibetan Plateau,
between the Yangtzee and Mekong rivers,
an extremely rare animal exists,
that's found nowhere else on earth.
The Yunnan snub-nosed monkey.
It's early morning,
and this troop is traversing the forest in search of food.
These elusive creatures are extremely endangered.
Fewer than 2,000 survive in the wild.
The head of the troop is the monkey king,
the dominant and only male,
in a troop of females and infants.
Males are twice the size of females
and have long black and white hair on their flanks.
He surveys his kingdom,
which may be as large as 50 square miles.
Every day he leads his troop,
made up of several females and their offspring,
on the search for food.
He keeps a lookout for competing groups
of bachelor males as he goes.
The coast, for now, is clear.
The Yunnan snub-nosed lives at the highest altitudes
of any monkey in the world, 14,700 feet above sea level.
Life at such great heights isn't easy.
To survive, these animals have evolved
some very unusual features.
Along with their shaggy coats to keep them warm,
they have peculiar looking noses,
for which they get their common name.
Their nasal bones are absent
and their nostrils are upturned,
a unique anatomy that protects them from frostbite.
It's not just their coats and noses
that help them survive in these extreme environments.
They have specially adapted blood vessels
that allow them to increase their uptake of oxygen
in these low oxygen, alpine forests.
This hypoxic habitat also has an impact on their diet.
While most leaf-eating monkeys live on plants and fruits,
such delights are scarce up here.
So these monkeys have evolved a peculiar diet,
one that allows them to survive where others fail.
They live almost exclusively on lichen,
which grows on the surrounding trees.
It draws moisture from the air
and nutrients from the tree bark.
It's extremely common in temperate forests like these.
A robust food source for the monkeys,
lichen is available through even the toughest winters.
Although it looks like a plant,
lichen is made up of two interacting organisms,
algae and fungi.
It can take many seasons to grow back fully,
therefore, these monkeys are always on the move.
Peeling lichen off the bark is no easy task.
But the dexterity of the snub-nosed's hands
means they make light work of it.
To stay warm, their hands are covered in thick fur,
giving the impression that they're wearing mittens.
It's early spring so the cold temperatures mean
the snub nose have something else to contend with.
Freezing conditions make the branches very brittle.
Choosing which will take their weight is a gamble.
The more supple branches, however,
can be used to their advantage.
This resourceful monkey makes the most of the bendiness
of this branch to propel him even greater distances.
The monkey king has led them well.
This area is covered in lichen.
The troop tucks in.
While the adults are focused on their food,
this juvenile has other ideas.
And soon he'll be getting ready to test his boundaries.
It's not only animals here
that have adapted to life at altitude.
Even the trees have evolved features
to survive the cold climate.
As the Mekong twists and turns through this elevated region,
it's surrounded by swathes of alpine forest.
Because the area is so remote,
the proportion of forest cover that remains intact here
is higher than in most other parts of China.
Conifers, endemic to this eco-region, grow in abundance.
Importantly, they are evergreens,
which means they can photosynthesize
whenever there is sufficient sunlight,
and their thin waxy needles prevent water loss.
This reduces their dependence on seasons.
Hardy pine cones protect the seeds
that are due to propagate soon.
A stark contrast to the hardiness of the pine cones,
the fluffy white blossoms of the pussy willow
stand out against the alpine backdrop.
The soft silvery hairs provide warmth
for the developing reproductive parts.
The Catkins appear long before the leaves,
and in late spring blossoms will give way to young shoots,
a brilliant color of jade green.
These first signs of life are a sure indicator
that spring has sprung.
As the Mekong river courses south,
it reaches the Lake Napa wetlands,
at an altitude of 10,000 feet above sea level.
It's dawn over frozen Lake Napa,
which is nestled in the Hengduan mountains.
Hundreds of birds have flown in from all over the region
to use these grounds as their wintering homes,
including the most elegant birds in China,
the rare black-necked crane.
With its distinctive black and white plumage,
this is the only crane species endemic to this area.
Internationally endangered, there are fewer
than 10,000 left in the world.
These black-necked cranes have flown in
from the Tibetan Plateau to the northwest.
Standing five feet tall,
the crane towers above other species on the lake.
This male uses his long legs
to expertly navigate the shallow water.
Their long beaks are useful tools as they search
for insects, invertebrates, and leftover grain
that may have fallen through the cracks of the frozen soil.
They move gracefully, as a team,
from patch to patch across the marshes.
Agricultural communities have occupied
this land for thousands of years.
As it's dry season, the water levels are low
and the farmland exposed,
making this the perfect habitat for migrating birds.
As their habitat is used for farming,
they have to share it with it some much larger neighbors.
The flock numbers in the hundreds
and they've travelled together to their wintering grounds.
Here, they split into their mated pairs and family groups.
This pair of cranes will mate for life
and are joined by their chick,
who doesn't stray more than a few yards from her parents.
At 8 months old she's identifiable
by her grey plumage.
She won't have her black and white feathers
until she's at least a year old.
The parents hold watch while their infant feeds.
The youngster has experienced her first migration.
When the time comes to return north,
she'll fly with her family,
but next summer, when she migrates back south,
she'll have joined a flock of non-mating yearlings.
She won't pair up with her own mate
until she's three or four years old.
She's looking for grain,
a welcome benefit of the nearby farmlands.
Building up her strength for the 1,000-mile flight north,
she'll spend spend 75% of her time foraging.
She and her mother feed whilst the male keeps a lookout.
All sorts of domestic animals mingle
with the seasonal visitors.
The pigs make for unlikely dining companions.
But this odd pairing isn't as random as it looks.
The pigs turn over the dirt,
which helps the crane find insects to feast on.
Heading back into the marshes,
the crane family keeps to the invisible lines
of its own territory.
Another family enters, at its own peril.
The two competing families display threatening postures,
throwing their heads backwards and hooting loudly.
The male isn't ready to give up his territory and charges.
Success, the other family quickly retreats.
Their food source is safe, at least for now.
The black-necked cranes will stay
amongst the snow capped peaks and frozen lakes
for another month until it's time to take flight.
Back up in the alpine forests,
the snub-nosed monkeys have made
the most of their food source
and now they're soaking up the midday sun.
In general, their days are made up of two halves,
traveling and feeding in the morning and afternoon
with a rest in the middle.
When they have stirred, it's time to take part
in their favorite pastime, grooming.
But this is about more than just looking good.
Grooming releases the hormone oxytocin,
often called the love hormone,
which reinforces their family bonds.
For the snub-noses these are unbreakable
and vital to their survival.
It's an important social skill, learned from an early age.
However, not all youngsters are so compliant.
This infant's scratching indicates
he's overdue a good groom.
He reluctantly submits for
an intensive grooming session from his mother,
although it looks like he's itching for adventure.
Having escaped from his grooming session
he sneaks past the monkey king who is otherwise engaged.
Although becoming independent is
an essential part of his development,
he's much too young to stray too far on his own.
Males typically leave their troop
once they're fully mature, at around three years old,
and join a group of bachelors.
But this infant is only a year old and looking for some fun.
He first tests his swinging skills,
not far from the watchful gaze of his mum.
But it seems this spirited infant
has set his sights further afield.
And starts to travel out of his family's territory.
Without elders to watch over him, he's at risk.
Bachelors can kill infants of competing males.
Oblivious to danger,
he's entered the territory of a bachelor group.
This is a group of male monkeys ruled
by a dominant head bachelor.
He doesn't wait for an invite
as he joins an older male on a branch.
It's a risky move.
This little monkey could be in hot water.
But instead of making a run for it,
the brave little one tries to initiate play.
He's soon put in his place by the bachelor.
Who bites his head and wrangles
him into a submissive position.
It's an important lesson in dominance.
The older bachelor has indulged the baby
for long enough and signals the play session is over.
Play is essential for learning his place in the hierarchy.
Perhaps he'll have more luck with someone his own age.
He's joined by a similar-sized infant
from a neighboring family.
The two test their physical limits
as they move through the canopy like a couple of acrobats.
These newfound friends dangle precariously from the trees.
If they were to lose their grip
they would plummet to the ground.
But their extremely quick reflexes mean
this tree top jungle gym is safe.
Someone has been watching them.
The head bachelor.
He could kill them in a matter of seconds.
But these babies don't seem phased by the potential threat.
They even attempt to play.
Despite the infants goading,
these bachelors don't seem up for a fight.
It's not breeding season so the males are less aggressive.
But they don't want to engage in play either.
The infants don't give up easily.
Eventually, the large male leads his gang of bachelors away.
Remarkably the youngsters attempt to follow him.
They're desperate to keep up.
But the bachelors aren't interested in tag-alongs.
These juveniles are obviously too young to be separated
from their family troop and will only slow them down.
Older and bigger bachelors move quickly
covering much larger ranges.
Eventually the enthusiastic youngsters simply can't keep up.
The intrepid baby finally decides
it's time to return to the safety of his mum.
Although the time will come when one day,
he won't be coming back.
Mountain streams trickle down through
the alpine forest and join the Mekong River
as it passes through acres
of agricultural farmland fed by the Mekong Basin.
Flying high above this network
of waterways is the bar-headed goose,
which makes a migration so perilous
it baffled scientists for decades.
The highest migration in the world,
this is a bird of death-defying extremes,
breaking records by flying at over 23,000 feet.
This flock of bar-headed geese has
flown over from the Tibetan Plateau
and will stay in this region until April.
They get their name from the two bars
of dark feathers around their heads.
Calmly feeding on the water,
these birds give no indication of
the extraordinary feats of physical activity
that they're capable of undertaking.
This is the dominant goose of the flock.
He decides where they feed.
and where he leads, others follow.
They have work to do.
They each need to gain over two pounds,
almost half their body weight,
before their summer migration north to Central Asia.
And theirs is no ordinary migration.
For they will have to scale a formidable obstacle.
The Himalayas.
What looks like an enjoyable way to pass the time,
bathing and preening, is actually careful preparation
for the journey.
By preening, this goose is lining up
his feathers almost like Velcro,
enabling them to be waterproof and more aerodynamic.
This flock numbers in the hundreds
and will stay on these tablelands for five months
until the time comes to leave for its summer home.
Knowing when to leave is an important skill.
Misjudging the timing of such
an extreme journey could be fatal.
Spring is progressing and the days
are getting warmer and longer.
This is the signal these birds need to take off.
Now the hard work begins.
Whereas most long-distance migrators
switch between soaring and flapping,
the bar-headed goose constantly flaps
its wings for the whole journey.
They undertake the world's steepest migratory flight,
then sustain those heights for hours on end
in an extremely low oxygen environment.
How they are able to sustain such high levels of activity
at such great heights was once a mystery.
It's now known that their lungs
are the largest of any goose species
and they breathe over seven times faster at altitude,
allowing them to take in oxygen at an incredible rate
as they push their bodies to the limit.
It's a migration like no other.
These super birds almost defy biology,
scaling some of the Earth's highest mountains
as they head towards their northern breeding grounds.
As the birds fly higher to the north,
the Mekong river descends in the opposite direction, south,
further dropping to an elevation
of around 6,500 feet above sea level
as it enters the Southern Himalayan Foothills.
The southern slopes of the mountains
trap water from seasonal monsoons,
blowing north off the Indian Ocean,
supporting forests of firs and deciduous hardwoods.
The Mekong is now flowing through
a very different looking habitat,
home to one of China's most elusive animals.
The red panda.
For an animal that survived the ice age,
the future of this extraordinary species isn't certain,
with just 10,000 individuals left in the wild.
Curled tight in a ball, a solitary male
staves off the cold.
Wrapping his bushy tail around him
helps him hold in body heat.
His thick amber fur has earned him the nickname Fire Cat.
When he wakes up, this young male has one thing on his mind.
It's mating season, and the only time this year
that he will come into contact with another of his kind.
Traveling down the slippery trees here can be treacherous.
But the fur on the soles of his paws
provides traction on the wet branches,
and a false thumb, an extension of his wrist bone,
allows him to grip tightly.
With his thick tail providing counter balance,
he makes it safely onto the forest floor.
This red panda is in luck.
He's discovered an understory of Bamboo
on the edge of his territory.
Bamboo makes up 95% of his diet,
so he won't pass up the opportunity
to feed on a bounty like this.
This ancient plant, which is actually a type of grass,
once blanketed the region but deforestation has meant that
bamboo is now only found in very fragile
and narrow bands across Yunnan's forests.
Fragmentation of his territory means
the odds are stacked against him
as he looks for a potential partner.
Living in such isolation,
males and females use chemical trails
to communicate and find one another.
He scents the ground with a weak musk-smelling secretion
from his anal glands,
hoping a female will pick up his scent.
The forest floor is covered in trails
and this shared information is crucial
for the panda to plan his next move.
Even walking leaves a trail,
he has scent glands located on the bottom of his feet,
a useful adaptation for these isolated creatures.
Not far off, a female sleeps high in the canopy
unaware that a male has entered the area.
But the male picks up a scent.
He follows the trail, checking for odors as he goes
to make sure he's on the right path.
The bottom of his tongue has a special cone-like structure
that brings fluid to a gland inside his mouth,
which enables him to decode
the scent trail of males and females.
Red pandas are the only carnivores
with this adaptation.
He continues to track and scent
as he travels deeper through the canopy.
But the female is nowhere to be found.
She must have woken and moved on
before he managed to arrive.
It's almost the end of the breeding season.
With so few animals left this may well have been
this red panda's last chance to find a mate.
Like all the animals that live along the Mekong,
preservation of the panda's habitat is key to its survival.
As fragmentation of the forest continues,
the future of these beautiful creatures
hangs in the balance.
The Mekong continues to flow down the mountain slopes
as it enters its lowest elevation in China,
the forests of Xishuangbanna.
At an altitude below 2,000 feet,
this is an important milestone on its journey
as the river leaves the temperate zone
and enters the tropics.
Spring's arrival means the monsoon rains
have blown in from the Indian Ocean.
Daytime temperatures average 77 degrees Fahrenheit.
Warm weather and high humidity gives rise
to an abundance of plants that make Yunnan
one of the most iconic botanical regions on earth.
Almost a third of China's orchid species
are found in this province.
Delicate flowers that are strikingly beautiful.
Growing side by side with the unusual Mayodendron plants,
which have flowers growing mid branch
instead of at the end of their stems.
It's a colorful habitat providing a stark contrast
to the mountainous forests that began the Mekong's journey.
Living deep within the tropical canopy is
a perfectly organized society that has been around
for at least 50 million years.
What these creatures lack in stature
they make up for in strength and numbers.
Weaver ants.
These ants are on a mission.
Their old nest has dried up and they must build a new one.
They deftly navigate commuter highways
as they patrol their territory.
These workers are all female,
non-breeding clones of a single queen.
And they are not to be messed with.
Other insects crossing their path do so at their peril.
A caterpillar makes for a juicy meal,
if they can transport it up the tree.
Their success depends on one thing, cooperation.
These ants seem to defy gravity
as they collectively haul their lunch up the tree trunk.
Traveling vertically is possible due to
powerful suction pads on their feet.
This vice-like grip gives them tremendous strength
and they've been known to support 100 times
their own body weight.
Many mandibles make light work.
Further down the trunk two ants seem
to have bitten off more than they can chew.
A third ant tries to help.
But this caterpillar isn't giving up without a fight.
These ants take no prisoners and use their brute force
to stretch the caterpillar apart.
Finally he stops struggling
and they carry him off to the colony.
The workers are building up an appetite
as they construct their new nest.
They line themselves up like staples
along the seams between the leaves.
Their legs hold onto one edge, their jaws grip the other.
While they hold their position,
other workers use larvae silk
to stitch the leaves together at the seams.
This team is short staffed so must recruit workers
from the surrounding area to help,
although not always by choice.
This weaver ant carries a worker to the site
so she can assist with the build,
whether she wants to or not.
With enough laborers on the job,
it will take the ants less than 24 hours
to build their new home.
From the smallest of residents, to the largest.
The figurines and paintings that adorn these local temples
give a clue as to which revered animal calls
these tropical forests home.
The Asian elephant.
In China, the Mekong is actually known as the Lancang river.
To the Dai people of South Yunnan this means
The River with Millions of Elephants.
Today this once honored elephant population
is just 200 strong,
a far cry from the many thousands that once roamed.
This female matriarch leads her herd
through the forest in search of water.
For hundreds of years, elephants have followed
the same routes along the Mekong,
which up until recently have been relatively undisturbed.
Although smaller in size than their African cousins,
the Asian elephant weighs in between 10 and 12,000 pounds.
Herbivores, they need to consume 300 pounds of food a day,
which means covering a lot of ground.
Elephants have 2,000 olfactory genes, twice as many as dogs,
giving them an incredibly acute sense of smell.
They have the remarkable ability to detect water
from as far as 12 miles away.
And this matriarch's trunk has led her
in the right direction.
The areas surrounding the Mekong are peppered
with these life-giving waterholes,
which are a natural source of important minerals
that the elephants need to supplement
their vegetarian diet.
Unlike most other mammals,
where the hip and shoulder joints
are in an angular position,
her legs are stacked almost vertically under her body.
This enables her to support her massive weight,
with padding around the toes acting like shock absorbers.
A younger female follows and it's not long before
the whole herd is enjoying what the waterhole has to offer.
These idyllic scenes belie a much more complicated reality.
The elephants' huge ranges have been cut back or destroyed.
What was once acres of forest has become highly fragmented,
turned into plantations and roadways
by the ever increasing human population.
This has led to a dangerous surge in human-animal conflict
and a steep drop in the number of elephants in the wild.
These rangers are on the frontline
of elephant conservation here.
They're tasked with finding ways
of reducing elephant-human conflict.
They measure elephant dung and interpret tree markings
to monitor ranging patterns of the animals.
They hope this information will help them predict
the elephant's movements and prevent them
from coming into contact with humans.
This herd has crossed into a canal next to a major roadway.
Surrounded by human litter, they are oblivious to any danger
as they continue to drink and cool themselves off.
Before long they're ranging towards the main road.
The park rangers have seen the herd coming
and warn those in the surrounding area to keep back.
When agitated, elephants can be extremely aggressive.
A huge traffic jam builds while the herd crosses the road.
Elephants have right of way in China.
And they appear to be in no rush.
They make it safely across.
Although watching these animals cross the road
may be entertaining for tourists,
if it wasn't for the quick action of the rangers,
things could have ended very differently.
This time, the herd passes without incident
and retreats back into the safety of the jungle.
From its source, the mighty Mekong river has carved
its way through an extraordinary land of extremes.
In the alpine canopy, the independent young snub-nosed
continues to test his boundaries.
On the mountain slopes,
the lonely red panda still searches for a mate.
Deep in the tropics,
elephants and humans attempt to avoid collisions.
Nowhere else in China is home
to such a diverse array of wildlife.
By the time the Mekong enters Laos,
this iconic river will have dropped
an astonishing 15,000 feet in elevation.
Its journey to the sea has only just begun.
(MUSIC PLAYING)