♪♪ ♪♪ NARRATOR: In South Central China at the Wolong Panda Center, there's a young cub that has never tasted freedom.

♪♪ His life is about to change.

This cub is special... chosen for the wild.

♪♪ But first he needs to discover what it means to be a wild panda.

♪♪ And his training team has to discover more about how pandas are brought up in the wild.

Even with teams of committed rangers and researchers and radio collars to track them, the released pandas have often struggled or even died.

Now there are just three years to prepare him for a panda's life in the wild.

♪♪ ♪♪ [ Birds chirping ] NARRATOR: A giant panda is carried up into the mountains... like an emperor.

[ Man speaking native language ] NARRATOR: Since 2003, nine pandas raised in the Wolong Panda Center have taken this journey to be released.

Even with teams of committed rangers and researchers and radio collars to track them, the released pandas have often struggled or even died.

A trickle of information back... tells of violence and hardship.

♪♪ ♪♪ Six mountain ranges draped in bamboo that's nine feet tall and impenetrable.

♪♪ Over a vast area, hidden, scattered, are only 2,000 wild pandas -- all there are.

♪♪ Filming them was thought futile.

Even just finding one is almost impossible.

Almost impossible.

[ Panda grunts ] Giant pandas are bears, relatives of grizzlies, black, and polar bears.

But, surprisingly, pandas don't hibernate, even though the temperature can drop to 30 degrees below freezing.

They have to keep feeding.

Bamboo provides only just enough energy, but it's almost all they eat for 14 hours a day.

To help it down, they roll the leaves into a sausage, with the help of a boneless pad from their wrist, the panda's unique "thumb."

Males start to search for females in spring.

Courtship, mating, and raising cubs in the wild is mysterious -- barely seen before and never filmed.

Wild pandas can be dangerous with huge claws powered by muscular front legs.

Many faces are scarred by old battle wounds.

The pandas here in the mountains are totally wild.

None have been released or have radio collars here.

That makes it harder, but it is the best chance to understand truly wild pandas.

♪♪ ♪♪ [ Panda chitters ] ♪♪ ♪♪ ♪♪ In South Central China are around 40 reserves.

They stretch across 300 miles of mountains.

♪♪ The cub's story starts at the Wolong Panda Center.

♪♪ For the pandas growing up here, it's a five-star hotel compared to living in the mountains above.

[ Whimsical music plays ] There's the "all you can eat" dining... and the kindergarten.

[ Panda squeaking ] The best part is hanging out with friends and family.

♪♪ Giant pandas in the wild are solitary, but in captivity, they are social.

It's not known why -- maybe generations of living with people or a quirk of evolution perhaps -- but they are natural clowns.

♪♪ Ah, this is the life!

It's...exhausting.

Looking after 40 or so pandas in Wolong are 85 staff with 59 enclosures, a research lab, and a panda hospital.

It's almost impossible to breed pandas.

Decades of matchmaking in zoos failed.

Artificial insemination was the breakthrough.

Our mother-to-be is pregnant, 5 months in, and about due.

[ Indistinct conversations ] Head keeper Wu Daifu is feeling the pressure.

The camera's ready to capture a rare moment.

♪♪ There.

The cub is born... blind, deaf, and hairless.

It weighs just 3 1/2 ounces.

[ Cub squeaking ] ♪♪ ♪♪ This cub is special... chosen for the wild.

♪♪ Like all bears, pandas have tiny, helpless young.

The cubs are the smallest newborns of all placental mammals relative to the mother's size.

♪♪ ♪♪ They'll both be isolated in a large enclosure to encourage his natural instincts.

She's been chosen for being a protective, instinctive mother, but she was born and brought up in captivity.

She knows nothing about living in the mountains.

♪♪ He needs to discover what it means to be a wild panda.

♪♪ [ Wind rushing ] Different altitudes have different species of bamboo, so pandas have learned to move around to find the best kinds for their diet.

They're not the only ones on the move.

Takin, giant golden goats that look like wildebeest, move up and down the mountains to feed on summer bamboo.

There's a world of other animals.

Golden snub-nosed monkeys, like elves with blue faces, live here.

[ Monkey chirps ] These mountain monkeys are unusual and rare.

There's another type of panda -- a red panda.

They're not actually related to giant pandas but part of the raccoon family.

In summer, pandas also come up here to avoid overheating.

But water is harder to find near the peaks.

Even above 6,000 feet, pandas can suffer from heat stress.

As the climate shifts, so will the best bamboo, trees, and water.

Animals will need more space to find new homes.

High in the mountains, autumn comes early.

♪♪ It's a bounty of colors.

♪♪ ♪♪ ♪♪ [ Panda squeaks ] In 1985, researchers found a hollow that had been used as a wild birthing den.

What they learned became another lesson for the cubs they were training for the wild.

♪♪ In the wild, sometimes the mother will not leave the den at all.

She stays with the cub and is forced to fast for the first month or so.

Like any bear milk, hers is among the richest in the world.

It carries more antibodies than any other animal's because the cubs are so underdeveloped and vulnerable.

[ Cub squeaks ] He's a month old now.

He's grown from 3 1/2 ounces to 4 1/2 pounds.

And when he's awake, he can see and hear.

♪♪ Over 10 years of motherhood, she can only have three or four young.

That is the lowest potential birth rate of any mammal.

♪♪ Autumn brings a dramatic change of season.

The monsoon from India and Myanmar is channeled up valleys through the Himalayas as far north as the Qinling Mountains.

It arrives as mist and carries rain or snow.

♪♪ Pandas -- mothers and cubs -- come down the mountains to spend the winter in the valleys.

♪♪ The mist settles as low cloud, hiding the pandas' wild world.

♪♪ ♪♪ At the base of the mountains, the Wolong Panda Center is milder.

♪♪ It's November, and he's now three months old.

♪♪ [ Cub squeaks ] ♪♪ An animal's personality develops early.

Emotional responses like courage or fear can be affected by as little as a single incident in the first few months.

♪♪ He's starting to get curious but struggles to escape.

His mother leaves more regularly to feed herself now.

So, at last, he's able to explore his world.

♪♪ Pandas have a phenomenal sense of smell, better than a bloodhound.

Their hearing is good, too.

Eyesight, less so.

♪♪ ♪♪ Strange... A weird-looking panda.

♪♪ ♪♪ ♪♪ Head keeper Wu Daifu and the team have to become pandas to visit our youngster.

They even spray themselves with panda pee.

The last thing these surrogate mothers want to be seen as or smell like... is human.

It's worth being a bit ridiculous.

Contact is kept to a minimum and always in disguise.

But today they have to do a health check.

This is the only contact he'll have with anyone other than his mother.

Being able to film this is a rare privilege.

Size, weight, teeth, and claws.

All healthy.

His life is more natural here than being with the other cubs all playing together, but is it anything like being a wild panda?

The training team are hoping to discover more about how pandas are brought up in the wild.

In the meantime, Operation Undercover is successful.

Totally fooled.

Well, maybe.

♪♪ [ Wind whistling ] It's winter back in the mountains and 30 degrees below freezing at night.

♪♪ ♪♪ In the high summer feeding grounds, the snow just piles up.

♪♪ But in the deep valleys below 3,000 feet, there is life.

♪♪ Bamboo is evergreen.

The wild parents feed while the cubs remain hidden.

♪♪ By early March, low-lying areas are beginning to thaw.

♪♪ Over the next month or two, the animals start to head back up the mountain.

The breeding season, "the rut," is about to start, and males head to claim the best areas.

♪♪ Single females follow.

Mothers have a more difficult decision.

The mating grounds are dangerous, and females with young seem to go into hiding.

♪♪ Takin, the golden wildebeest... and golden monkeys follow.

♪♪ This year, they are shadowed by the first month-long expedition from Wolong.

The team is on a key mission.

As part of the reintroduction process, the head keeper, Wu Daifu, wants to find a panda breeding ground.

Discovering his cub's potential to breed in the wild is crucial to the program.

Cameramen Jacky Poon and Wu Yuanqi lead a filming team each to increase the chances of finding a panda.

For three years, the film crew and rangers search for breeding grounds.

All the animals here benefit from the protection of the panda reserve.

[ Monkey hollers ] [ Animals calling ] Days of exhausting trekking to find the breeding grounds.

And then... a sound from the next valley, their first panda calls.

[ Panda barking ] The scouts find fresh panda tracks.

[ Conversing in native language ] And there -- a wild panda.

One of the rarest sightings in nature.

[ Man speaking native language ] NARRATOR: Wu Daifu sees his first wild panda after 15 years of working with pandas in sanctuaries and breeding centers.

Cameraman Jacky Poon takes up the story.

POON: When you encounter wild panda, there's nothing cute and cuddly about them.

Their eyes are very focused and very alert of what's going on.

They are just a big bear.

NARRATOR: He's probably the dominant male in the area.

He may weigh over 300 pounds and, if he stood up, reach almost seven feet.

He's fearless and curious.

He may never have seen people before.

POON: We have to be really cautious and really careful when we are doing this.

Do we have to give him space?

What is the safety distance between this individual and us and the camera?

And we always have to think, "Okay, if anything happens, what am I going to do?"

NARRATOR: The team follow him along a narrow mountain ridge.

This is the time of the spring panda rut, the month where males gather to find females to mate.

Pandas can smell hormones.

Another panda has left a urine message on a tree.

He'll add his own.

He does a handstand to get as high up the tree as possible so that he seems bigger.

The wild panda catches another scent -- a female in season.

He starts to roll in the snow and leaf litter.

He's mixing in his own smell.

It's a conversation in scent.

♪♪ It seems like he's playing, rolling around, but this is serious business.

This is a territorial wild bear, ready to defend his patch.

♪♪ There's a spot of blood in the middle of his flank.

It's the first sign of things to come.

♪♪ He rolls in the scent marks of a female and then walks towards the team.

For Jacky, it's a moment of panic.

POON: All of a sudden, the panda comes this way.

I get the kit and just run the other way, just me shouting at Wu, "Go!

Hurry up!

Hurry up!"

NARRATOR: The panda completely ignores the rangers and crew trying to get clear and just lumbers on.

POON: Yeah, a bit too scary.

He's actually gotten really close.

You can see we're just running away.

And then, this is the second time he goes towards me.

I try to hold the shot as long as possible, but it's a bit -- a bit too scary.

NARRATOR: Three times he wanders towards the crew, and despite getting close enough to touch, ignores them completely.

He's so focused on finding a mate, nothing, it seems, will distract him.

A panda sees the world through his nose.

It may be tough out here for a captive-bred panda that hasn't the experience of growing up with wild smells.

Wu Daifu, a world panda expert, realizes it won't disturb the wild panda if he moves in a little closer for a better view.

[ Man speaking in native language ] ♪♪ What becomes clear is that the world of a wild panda is complex, chemical, and, judging by the blood, dangerous.

[ Panda grunts ] The team returns with the reintroduction project seeming more real now and more difficult.

The weather this spring's not much better back at Wolong.

The cub is now seven months old.

His instinct is to climb trees, but his mother's very protective.

She'll teach him everything she can, but she grew up here, playing with her friends and treated like royalty.

Maybe trying to keep the cub on the ground is a maternal instinct or perhaps when she was a cub 20 years ago, a keeper or someone was afraid for her and stopped her climbing.

He has instincts, too, perhaps triggered by his semi-wild upbringing.

[ Panda grunts ] [ Panda growls ] "No, you don't!"

[ Panda growling ] [ Cub squealing ] [ Cub squeaking ] He doesn't go far up the tree.

His mother's anxiety has affected him.

Exploring in the wild would be dangerous with predators and rival pandas around, but here on the ground, in an enclosure, he is safe.

♪♪ He's gaining in confidence and coordination.

Hmm.

Maybe.

♪♪ ♪♪ ♪♪ [ Cub squeaks ] His instinct to explore his world is good, but his coordination, less so.

♪♪ He doesn't seem like an animal meant for the ground at all.

♪♪ While our panda family is kept isolated, the other pandas are let out to play together.

They should be shy loners, but among friends, they turn into party animals!

After a few months in a panda nursery, they have graduated... to the panda kindergarten.

♪♪ It's still a puzzle -- why do panda cubs instinctively love playing so much?

♪♪ ♪♪ Most of the pandas born here and across China are kept for breeding.

Some of them even have genes from areas where pandas are now extinct.

Every one of these cubs counts.

♪♪ ♪♪ Isolated in his big enclosure, the panda cub starts his second year of training.

He's a clumsy climber.

His wild development's been held back.

♪♪ Mother's fatty milk and little exercise have made him chubby.

♪♪ ♪♪ [ Cub squeaks ] "Whew!

That was hard."

♪♪ Bamboo doesn't grow in the enclosure.

It's delivered.

But he doesn't care about bamboo.

He's still on milk.

Ah.

Solid ground.

Autumn turns again into winter.

The wild pandas are back in the valleys.

♪♪ Pandas evolved from other bears 23 million years ago at a time when grasses, including bamboo, were replacing forests.

Fossilized skulls found in caves revealed that there was a pygmy panda species and an even more giant panda.

Even then, these prehistoric pandas had teeth adapted for eating grass.

♪♪ Young pandas are little known from the wild, never filmed, but dens in trees are thought to be important.

Old forests are like high-rise homes.

♪♪ If more could be discovered about how cubs survive in the wild, it could be copied in Wolong.

♪♪ ♪♪ It's March, and the second big expedition into the Qinling Mountains sets out -- another month of trekking long distances to find wild pandas.

Thanks to the snow, it's possible to find and follow a panda's trail most days.

The males are again competing for females, bellowing like stags.

[ Male pandas bellowing in distance ] [ Man speaking native language ] Trees are clawed, and the smell of panda is there, even to human noses.

[ Man speaking native language ] Then, one day, a discovery.

Blood in the footprints.

This year already feels different.

The dominant male is facing a challenger.

The pandas are more nervous and always melt quickly away into the bamboo.

[ Pandas grunting ] With the prospect of spring, the other animals are moving up the mountains.

Red pandas will eat almost anything, but here, bamboo is their main food.

Small goral antelope move up and so do groups of takin that also specialize in eating bamboo.

Bamboo is rich in protein, and the animals are following the brief seasonal new shoots.

March brings unpredictable weather, and a storm moves in.

The tawny owl sits it out.

Then, a week later, the team discovers something astounding -- a male panda under a tree, and a second male -- a challenger -- in the bamboo.

Above them in the tree, a third panda, It's a female, probably the only one in the area, so she's their one chance.

Guarding her is the dominant male, at the base of the tree.

Nothing like this has ever been seen before.

[ Panda growling ] [ Panda growling ] The rival backs away.

[ Panda growling ] Female Pandas are only fertile for a couple of days, so every male battles to be in the right place at the right time.

After an hour, she starts to come down.

[ Panda grunting, calling ] The male has to be careful -- females will attack and can injure males if they don't want to mate.

The couple fight for only a second.

He retreats, and she makes her escape.

She's not ready.

Both males will follow her until she comes into estrus.

With the snow melting, tracking is difficult.

The pandas become almost impossible to find.

[ Pandas growling in distance ] One wet, misty dawn, the team finds the pair.

[ Panda squeals ] The female is above.

It's the same stand-off.

This "mate guarding" behavior is similar in many animals.

He's trying to keep her away from his rival.

She may just be hungry or may just prefer the other male.

She challenges the old warrior, and again he backs down.

The balance of power isn't just with the males.

♪♪ Calls between the male rivals become more frequent.

[ Pandas calling ] ♪♪ A showdown seems inevitable.

[ Pandas calling ] [ Panda roaring ] ♪♪ ♪♪ The challenger is to the left.

He's younger and takes the high ground, an advantage in a fight.

The old, dominant male backs down.

But then he rallies and comes back in.

♪♪ It's a psychological battle as much as one of strength.

This stressful build-up has taken weeks.

♪♪ [ Panda grunting ] If you look carefully, you can see why the old male is wary -- his face is in tatters.

And he's exhausted.

♪♪ The challenger moves back and skirts around him.

[ Panda growls ] ♪♪ This struggle, this dance around the female, takes tactics as well as strength.

It's a conflict between experience and youth.

Timeless.

♪♪ ♪♪ A week later, the female is found in a tree with no sign of either male.

Instead, on the forest floor is another mating dance -- golden pheasants.

It's all show for them.

The courtship of the circus.

♪♪ This seems like a much more fun way to choose a mate.

♪♪ ♪♪ The female panda peers down.

The younger male, and no sign of his elder.

Youth has won out.

He sniffs, licks the ground, and drools.

She's come into estrus and is finally ready.

♪♪ Then, in what they may imagine is a discreet corner, they mate.

The roaring, scent marking, fighting, and being held hostage may actually trigger her ovulation.

It's similar in other bear species, and it explains why pandas have such problems breeding in captivity.

Wild animals lead complicated lives.

♪♪ Whether our cub in Wolong will have a clue what to do... is a big question.

Another year into his preparation for release, and he's now 3 -- the panda equivalent of a teenager.

In the wild, his mother would be starting to part ways -- to let him fend for himself.

But there's no sign of letting go here.

They play together, just like she learnt to in the panda kindergarten with her friends.

♪♪ [ Panda grunting ] ♪♪ He's still suckling.

♪♪ Their isolation has made them closer.

Far from helping him to become self-sufficient, he seems more dependent on her.

He's a big baby!

Having seen male pandas in the wild, it's hard to imagine he'd do well in the battle for a mate.

It may be just a teenage phase, but he seems to have gone backwards.

♪♪ He's just a giant softy.

She's no better.

♪♪ He can't even eat properly.

♪♪ [ Cub squeals, body thuds ] You've got to roll the leaves up into a sausage, remember?

Bamboo shoots bamboozle him.

[ Cub grunting ] Yet within the teenager, a wild instinct is emerging.

He's just started scent-marking trees and restlessly patrolling.

But just when you think he's growing up, he's back to being a cub again.

Training for a future alone in a big, bad world is something all parents struggle with.

It's impossible to prepare for the unknown and the inevitable separation.

♪♪ Freedom has a price, especially for those left behind.

♪♪ ♪♪ ♪♪ The cub, almost an adult now, is carried into the panda reserve.

The crate is covered to minimize human contact.

His first steps without his mother.

♪♪ Imagine the feeling, leaving mum, entering a new, bewildering world.

But it may be just what this cub needs to grow up.

He's in a huge enclosure within the reserve, safe from wild males.

He'll stay here for as long as it takes, getting used to the wildlife and freedom.

♪♪ The enclosure door will be left open for him, when he's ready.

Maybe next year.

♪♪ The following spring, it's the last expedition into the mountains, this time for six weeks.

♪♪ There's good news for wild pandas.

The 40 or so different panda reserves are to be absorbed into a massive new protected area, three times the size of Yellowstone, over 10,000 square miles.

This will make a huge difference, especially as a changing climate threatens the bamboo forest.

♪♪ After weeks of searching on foot, the team find the dominant young male, presumably the winner of last year's rut.

He's following a female.

Females only breed every few years, so she must be a different one.

♪♪ The team is surprised to witness them mating.

Maybe pandas in the wild don't find it so difficult after all.

[ Panda grunting ] ♪♪ The old male is found, retired in a den.

He's on the higher fringes of his old home range, marginalized, out in the cold.

His teeth are badly worn.

Bears' teeth can't cope with coarse bamboo for 20 years.

His face still has the battle scars from last year.

Solitary pandas like our old male can travel significant distances.

One radio-collared panda travelled hundreds of miles, going between reserves and crossing rivers and main roads.

It was this discovery that partly inspired the massive new panda reserve, protecting all other wildlife, as well.

The old warrior will roam widely, keeping out of the way of other male pandas now.

But he does seem to have one friend -- a wild boar.

To the team, it's Pooh-Bear on a new adventure with Piglet.

♪♪ One day, while tracking a female, there's an extraordinary discovery -- the most important find of the three-year expedition.

A wild panda cub.

Even the most experienced ranger has only seen one twice in 23 years.

[ Cub squeaking ] ♪♪ [ Squeaking continues ] The crew made sure that they were out of the way by setting up on a high cliff.

It's an emotional moment for cameraman Jacky Poon.

POON: This scenario has been here since yesterday, so 24 hours ago, and the baby is still up here in the same tree.

And this is really rare.

And we have never actually seen this before.

So has the rangers.

They've never actually seen this before.

But this is what seems to be happening right now.

We have been monitoring the baby, and we are hoping that the mother will come and collect the baby by tomorrow.

NARRATOR: The cub -- probably six to nine months old -- stays in the tree for over two days, unfed, while his mother is away.

His black-and-white markings match the branches as a surprisingly effective camouflage.

It's another piece of the puzzle.

He's hiding up there, most likely as a protection against hormone-fueled rutting males.

In other species of bears, males kill first-year cubs because having a young cub will stop a female from mating.

The team refocuses their search to look for cubs in trees.

They found another one, younger, also up in the branches all day.

This is not a one-off.

This has to be normal wild panda behavior.

This has significant implications -- young pandas need trees as well as bamboo to survive.

♪♪ Perhaps, for climbing, the cub knew better than his mum all along.

This wild cub means next year's training may need a rethink.

Three years and over hundreds of miles on foot have uncovered many of the important secrets of a panda's life in the wild.

♪♪ The newly enlarged reserve helps all the animals thanks to the pandas.

And somewhere out there is a young male from another world -- our world.

It's been an extraordinary investment into one animal.

Now he's where he should be and looking forward to some serious adventures... in his own time, of course.

♪♪ To order this "Nature" program on DVD, visit shopPBS or call 1-800-PLAY-PBS.

This program is also available on Amazon Prime Video.

♪♪ ♪♪ ♪♪ ♪♪ To learn more about what you've seen on this "Nature" program, visit pbs.org.

♪♪