[ Birds chirping ] -Deep in the monsoon forests of Nepal, there is one special place... ...where a river has shaped the land... ...creating an island full of life... ...home to an icon of the natural world... ...the Bengal tiger.

[ Tiger growls ] These secretive big cats are notoriously difficult to film.

[ Tiger growls, hisses ] But on this island, they're starting to reveal themselves.

-There's something really strange about being on foot with a tiger.

-And unlike in other parts of their range, here, they can be filmed from the air... -He is ginormous.

-...making this one of the best places in the world to observe their behavior.

-Right there.

-Now, for the first time, an expert team is following the tigers through the day... -Ooh!

Ooh!

Film, film, film, film, film, film!

-...and even... into the night.

-[ Gasps ] -This time, a king returns... -[ Whispering ] You don't wanna mess with him.

-...looking to make his mark... [ Tiger growls ] ...and assert his dominance.

-This is a male with the whole family.

[ Tiger growls ] -Tigers are so much more complex than we every thought possible.

♪♪ (upbeat music) ♪ Ah, hey ♪ (upbeat music continues) [ Birds chirping ] -Western Nepal.

The crew are back after two months away.

Led by local guides and sisters Sushila and Manju Mahatara, they're following the island's tiger mothers... -Oh, there she is.

Stop, stop, stop, stop.

-...Goma, a mature tigress who is raising two cubs, and her adult daughter, Mala, who was last seen with one surviving cub.

[ Thunder rumbling ] As the monsoon season approaches, temperatures exceed 100 degrees.

The forest is growing thicker.

-It's so dense and so wild.

-And the tigers are becoming more elusive, making it difficult to follow them during the day.

-Monsoon season is completely changing the behavior of our tigers.

-For the first time, the team is preparing to track them after dark.

-We're gonna have to move to our thermal cameras.

That will help us follow the tigers into the night.

-This thing's a beast but it's gonna allow us to pick up tigers from three miles away.

[ Birds chirping ] -Biologist Dan O'Neill and guide Sushila are hoping to catch up with Goma's family to find out just how active they are at night.

-[ Whispering ] So, this must be the pool that they drink from.

-[ Whispering ] Yeah.

-Mm-hmm.

Yeah, I think so.

-Dan and Sushila are aiming to blend into their surroundings, while the crew sets up thermal cameras behind them.

[ Insects chirping ] With night vision six times better than ours, the tigers have the upper hand, and everyone needs to be extremely vigilant.

-Super eerie driving down these roads at night because you never know what you're gonna come across.

And equally, we just can't see anything into the darkness apart from through this camera.

-Tigers have rarely been observed at night, and very little is known about their nocturnal behavior.

-But this is, uh, all of a bit of an unknown quantity, really, which makes me excited and nervous at the same time because no one's ever tried to follow tigers at night like this.

[ Whispering ] Dan and Sushila are staking out this watering hole.

We know that Goma's got a kill up here and she's likely to come down to drink.

This is gonna be the best chance to get eyes on her.

-[ Whispering ] She's coming down the bank.

♪♪ -[ Exhales sharply ] -Wow!

-[ Chuckles ] -She's drinking.

She's so close to us.

She's literally 25, 30 meters from us.

-[ Whispering ] This is so strange because... you can't see any stripes.

-Thermal cameras only detect heat, making a tiger's color patterns invisible.

-If I didn't know that that was a tiger, I might have no idea what kind of big cat that was.

-She's up.

She's up.

She's moving.

Oh, whoa.

Okay, she's looking at us.

She's looking at us.

-Yeah.

-She stared directly at Sushila and Dan.

I mean, there's no doubt that she can see us.

At night, these cats definitely have the upper hand, and she probably thinks we can't even see her.

She's having a bath.

♪♪ As soon as the sun sets, it's her chance to -- to finally cool down.

-Yeah.

Cubs.

[ Tiger calling ] -Oh, you hear?

You hear?

-She's calling the cubs in.

♪♪ [ Calling continues ] Okay, there it is.

-There's a cub.

The cub's coming down.

-Oh, wow.

Look at that.

[ Calling continues ] That's the female cub.

She's looking right at us.

Just staying dead still.

Oh, it is incredible to be stared at by a tiger like that.

I think this one's the male.

Unbelievable.

-At a year old, the cubs are beginning their journey towards independence.

-It's amazing how much they've grown.

They don't really look like cubs anymore.

They're sort of gangly adolescents.

-They are totally aware of us right now.

I mean, can you see them switching?

One looks, and another drinks.

They are very wary.

But to do that without mum -- that is a level of confidence, isn't it?

It's like she's giving them these lessons.

Now it's time for you to go down and have your drinking experience on your own.

Stay vigilant.

Look after one another.

♪♪ [ Tiger calling ] I mean, it's such a rare thing to be able to see.

You never are able to follow tiger cubs through their adolescence like this.

[ Calling continues ] -The thermal cameras just give us a window into the world that we've never seen.

All these intimate moments.

[ Engine starts ] -Goma is leading her cubs into the forest, and Max is following.

[ Insects chirping ] [ Camera whirring ] -Everyone stay as still as you can.

She's checking us out.

She's coming right towards the car now.

Ooh.

It's getting a bit too close for comfort.

We need to pull out.

Hey guys, get ready to move.

Guys.

Mate, we need to get out of here.

[ Engine revving ] Be careful.

Whoa.

Whoa.

[ Exhales sharply ] Phew.

Oh, my goodness.

-That was insanely close.

Do you need a new pair of underwear?

-[ Chuckles ] I think I need a stiff drink.

-I could see very clearly how close she was, and it was -- was really close.

She was interested.

-At night, they're just so confident.

-Yeah.

They probably think that we can't see them.

-The team pick up signs there may be another tiger roaming the island.

[ Radio beeps ] -We're hearing a lot of roaring coming from the northeast.

[ Radio beeps ] [ Drone whirring ] -Anna is using the thermal drone to check who's out there.

-Ooh.

Just got the drone up and pretty much immediately have found a tiger.

And judging by the size of its neck, this has gotta be a male tiger.

Oh, he's scent-marking.

-Tigers leave their scent to communicate status, mark territory, and attract mates.

-This looks like a bit of a territorial march for this tiger.

I think this could be the dominant male.

This could be Bandheil.

-Bandheil is the most powerful tiger in the area.

The crew have no idea how he'll behave at night.

-I think it's a bit worrying.

-A male tiger this close could be dangerous.

-[ Exhales sharply ] Might be about to come face-to-face with... the biggest big cat.

[ Tiger growling ] ♪♪ [ Exhales sharply ] [ Exhales sharply ] That was fleeting, but that was terrifying.

Bandheil just looked straight at us.

[ Tiger growling ] [ Exhales sharply ] You really start to appreciate how huge they are when they're that close to you.

You don't wanna mess with him.

Yeah.

Hm.

-Unlike other males who only pass through, Bandheil shares territory with the females here on the island and has been seen mating with them.

This is a rare chance for the team to follow a tiger father.

-Tigers are known to be solitary.

Male tigers don't get involved with the cubs.

-He may not even recognize his cubs and could pose a threat if he finds them.

-He maybe would just kill them, right?

-With Bandheil on patrol, Goma and her family would be wise to lay low.

♪♪ ♪♪ Using remote cameras, the crew want to track Bandheil's movements across the island.

-Okay.

-As the dominant male, his territory overlaps that of several females.

The team wants to find out how the mother tigers respond to his presence.

♪♪ Two months ago, Goma's adult daughter, Mala, discovered just how dangerous male tigers can be... [ Tigers growling ] ...when an unknown intruder killed two of her cubs.

-[ Gasps ] -That is horrible.

-That male seems to have left the area.

Now Dan and Sushila want to check their remote cameras for signs of Mala and her surviving cub.

♪♪ -Track.

-Oh, yes.

It's Mala, though.

I can't see the cub yet.

All right, let's have a look.

There we go.

Okay.

[ Gasps ] -Ooh!

-Is that Mala?

Wow.

That's today.

Morning light.

She's such a beautiful cat, isn't she?

-Yeah.

-It's just really nice to know that minutes ago she was right there having a drink and she looks great condition.

People, right there, right there!

-Yeah.

[ Chuckles ] -The tigers here have had to adapt to sharing their home with people.

-They're fishing just here.

-Mm-hmm.

-And she's probably sat somewhere up here hiding.

It's amazing how close she is to people all the time.

Is the cub there, though?

-Only half of tiger cubs make it to adulthood.

-No cub with her.

It is worrying.

-And for Mala, who is raising her first litter, the odds are even lower.

-[ Gasps ] Cub!

Oh, hello!

Aww.

Lauti.

-Lauti.

She's growing very well.

-In just a few months, she'll be quite a big cat.

And her chances of survival are gonna be so much higher.

Just needs to make it through the next six months.

-Yeah.

-Flying the drone, tiger guide Manju has just picked up Mala and Lauti.

It's an opportunity to see how Lauti is developing.

Tiger cubs gain the skills they need through play.

[ Cubs screeching ] At six months old, Lauti will be joining her mother's hunting expeditions.

But first, she needs to learn one of the most critical skills for any tiger -- stealth.

[ Cub screeching ] After losing her siblings, Lauti only has Mala to practice on.

But her play is attracting unwanted attention.

-Oh, look at this!

-Weighing two tons, a greater one-horned rhino can be unpredictable.

It's the wrong target for hunting practice.

-That's not good.

That's not good for her.

♪♪ ♪♪ ♪♪ ♪♪ Oh!

She ran.

Good job, Lauti.

-On an island full of danger, keeping a low profile will be crucial to Lauti's survival.

♪♪ Checking footage from the remote cameras, Dan is looking for any sign of Bandheil.

-Hello, Goma.

Ha!

Her cub.

Oh.

That's Bandheil.

You can see from the stripes and the markings on the face.

He's so interested and really, really licking, sniffing the exact spot where Goma walked up.

This is really close to where she's keeping her cubs.

When he's licking the ground like this and pulling in those scents and moving them around this specialist organ called the Jacobson's organ, he's basically trying to read the information left behind by all the cats in the area -- whether a female has cubs or if she's looking to mate.

He must be aware that she's got cubs because he can smell it.

Their scent will be everywhere here.

-Apart from when they mate, male tigers are solitary.

So it's unclear why Bandheil is following Goma, who won't be receptive until her cubs are independent.

-To see a big adult male, regardless of who he is to her, in such close proximity is really worrying.

[ Tiger growls ] Goma, in fear of him killing her cubs, will avoid any male that comes into the area If he comes across Goma and Goma doesn't like it, she's gonna get herself into a scrap, and the last thing a female tiger wants when she has cubs is to get injured because how's she gonna look after them?

-Raising young cubs surrounded by so many other tigers isn't easy, but Goma has kept her cubs alive through their most vulnerable year.

-We know how brutal tiger lives can be.

We saw what happened to Mala's cubs, and I just was really hoping that that wouldn't be the case for Goma.

And luckily, all of her years of experience are paying off, and she's managed to keep these cubs safe and well.

[ Tiger growls ] -Goma has shown she can navigate the island's threats.

But with Bandheil tracking her, she may be facing her greatest challenge yet as she prepares her cubs for independence.

-The way that this cub is gnawing into this kill that they've got, you can see that they've -- they've got a taste for blood.

[ Tigers growling ] One of these cubs is much more feisty.

Booted the other one straight off the kill.

Aw.

There is always one.

-The team has decided to name the cubs Asa... and Bune.

Male cub Bune is the dominant sibling.

-Goma is an incredible mum.

She seems to be doing an amazing job at keeping Asa and Bune well fed.

The girl is always gonna be a little bit smaller than its brother.

-Bune needs to gain over 200 pounds over the next year before he leaves his mother.

-And you can tell that size matters at the moment because the big brother is managing to muscle in on all of the food, getting the tiger's share.

-Goma's cubs now need to learn to catch their own meals.

[ Birds warbling, chirping ] As the team prepare to follow the tigers into the night, the heat is bringing the island's residents to the water.

And Anna has just found Mala and Lauti.

[ Tigers growling ] [ Insects chirping ] -[ Whispering ] It's really nice to see the bond between Mala and Lauti.

They just seem really, really close-knit.

Lauti has just submerged in the water, cooling off.

So cute.

Ha.

That is the best way to drink water.

Just submerge yourself in it.

-Mala now needs to catch a meal for them both.

At night, she gains an advantage over her prey.

Lauti must now watch and learn.

-Tigers are basically designed for the night time, their eyes especially.

They've got really big, round eyes, and that means that they allow so much more light in.

She's staring at two deer that are right in front of her.

-But Mala's success depends on one factor she can't control.

-Oh, Lauti's moving in.

Lauti's moving in towards the deer.

♪♪ Going straight towards the deer.

It's really close to them.

♪♪ Ohh.

Ohh.

No.

-Lauti is not yet as stealthy as her mother.

-I wish I could get into Mala's head for a moment.

I wonder if she's annoyed?

-If she's to catch a meal, Mala will need to make sure Lauti knows to make herself invisible.

♪♪ [ Birds chirping ] Early morning, and the team has picked up something unusual.

Goma is moving her cubs towards the river.

♪♪ And Manju is tracking them.

♪♪ As water levels rise during the rainy season, Goma and the cubs must adapt.

-Look at them!

Wow.

[ Laughs ] ♪♪ -There may be another reason Goma is moving her cubs.

-Whoa.

-Bandheil.

♪♪ ♪♪ ♪♪ -There's something going on.

He's crossed over the river on a real mission, and now it's clear that he's marking his territory.

And I guess he's just saying that, "This -- This territory's mine."

And he's doing this flehmen response where they -- almost sort of tasting the air.

-It appears Bandheil is asserting his claim over the island and the resident females.

If Bandheil is pursuing Goma to mate, he could attack Asa and Bune.

-This is potentially really, really dangerous.

He's gotta be one of the biggest male tigers in the area.

If a male comes in and thinks it's not their cubs, they could kill them.

They wouldn't even think about it.

They will just go straight for these cubs.

♪♪ Hang on.

She's just made a move towards him.

-With cubs depending on her, Goma can't afford to get injured.

But she's their only line of defense.

-They're about four meters from each other at the moment.

Ooh.

What is she's doing?

Ooh, he's charging, he's charging.

[ Tiger growling ] She's being submissive at the moment.

She's essentially saying, "Don't come any closer.

I don't want to fight."

-For now, Goma has stopped Bandheil's advance.

-She's really showing what it means to be a mum, and that is to be a protector.

-And Bandheil seems to have gotten the message, at least for now.

♪♪ [ Thunder crashing ] The sudden arrival of a monsoon storm forces the team to take cover.

-Goma is sat over there with her two cubs right now.

There's lightning coming from all directions.

[ Wind whipping ] These are really, really unforgiving storms.

And we -- And we have a lot of equipment that can get destroyed really quickly.

It's unreal.

Oh, my gosh, the tent is filling in!

Da.

Oh, I expect Goma's having a horrible time right now.

It's the beginning of the monsoon season, so these are just gonna be getting more frequent and more intense.

[ Rain pounding ] [ Thunder rumbling ] I don't even want to hold this metal bar.

I feel like it's a lightning rod.

This is what these cats have to contend with all the time.

I can only imagine how uncomfortable it is.

They're probably all together, huddled up.

The second this goes, we need to be out there and trying to relocate her.

[ Thunder crashing ] [ Birds chirping ] ♪♪ -With concern growing for Goma, Dan is keen to check on her and the cubs.

-The water level is definitely going up.

Yeah, it's really, really high.

Okay, I'm swimming.

Well, the tigers have to cross this, so so do we!

[ Whistles ] Ooh!

[ Radio beeps ] -Hey, Dan, we have a tiger coming in your direction.

[ Radio beeps ] -Okay, how far away is she?

-Currently 8-0, 80 meters away.

-[ Whispering ] Okay.

I can see her.

Hello, Goma.

She is so stunning.

Look at that.

No cubs, though.

Hopefully she's left them somewhere safe.

There's been quite a lot of rain, so all of her scent marks will have washed away.

And that puts her and the cubs in a not-so-good situation because other tigers might try to move in.

-Goma looks to be on a territorial patrol.

She may be scent-marking to lead Bandheil away from her family.

-She's definitely gonna be moving a lot now.

♪♪ ♪♪ -To help track Goma after dark, Anna is taking over with the thermal camera.

[ Engine revving ] [ Insects chirping ] Goma has returned to her cubs Asa and Bune, who are practicing hunting skills.

[ Cub growls ] And it's time to put them to the test.

-[ Whispering ] Asa and Bune are like twins.

They like to do everything together.

They just want to play with everything around them.

-With prey nearby, Goma seems to be signaling.

[ Tiger growls ] -It kind of looks like Goma uses her tail to direct her two cubs.

-When hunting as a family, subtle commands appear to be important.

It's like a secret language.

-But they seem to use their tails and their ears as signals.

They have created a way to communicate so that they are absolutely silent because that is what they rely on going in as they ambush their prey.

-And this time, the cubs are taking the lead.

-Oh!

There's one cub... that looks like it's got a plan.

Staring at the deer in front of it.

Oh.

It's going.

[ Laughs ] This tiger cub has no idea what it's doing.

It's literally just walking straight towards the deer.

Ooh!

[ Chuckling ] This cub is kind of hilarious.

Bune seems to be more playful than his sister.

He's more confident.

He's always out in front.

He's doing things he probably shouldn't be doing.

♪♪ [ Gasps ] Whoa!

No way!

No way!

They just chased a deer straight into Goma's mouth.

That was incredible.

Goma wasn't even looking.

She was walking in the opposite direction, turned around to a deer just coming straight towards her.

Okay, so, Asa and Bune have just helped Goma with a hunt.

Was not expecting that.

[ Insects chirping ] Okay, this is interesting.

Goma has just left the cubs to it.

She just took the deer down, but she's just walked away, and now the cubs are suffocating it.

It looks like Goma is starting to give them some responsibility in these hunts.

The fact that she trusts them to essentially finish the job, it means they are coming along in their hunting skills.

-Under Goma's guidance, Asa and Bune are getting to grips with operating at night.

[ Cubs growling ] But for the crew, it remains a challenge.

[ Engine revving ] -We're stuck.

We're stuck.

Okay.

[ Radio beeps ] I don't know if anyone is copying us but we're currently stuck.

Um, trying to get ourselves out of a sticky situation here.

-With tigers around, they must work quickly to get the vehicle out.

She's here.

I can see her, guys.

Guys, get in the vehicle.

Get in the vehicle.

Get in the vehicle.

-And now Goma has noticed them.

-She's literally looking right at us, guys.

-Oh!

-Oh, I think I can see lights.

Ahh, okay, okay.

Goma's only about 40 meters from us right now.

Literally right there.

It's okay.

She's moving away.

[ Exhales sharply ] Yeah.

Let's get out.

-Finally, the team can free their vehicle.

[ Engine revving ] -Let's go!

[ Revving continues ] [ Crickets chirping ] Following Goma's trail, the crew have picked up Bandheil.

-I've got drone team's feed.

He's scratching that log.

That's how they sharpen their claws.

-And he's just tracked Goma down.

♪♪ -They're coming right up to each other.

They're greeting each other.

They're actually greeting each other?

[ Tiger growls ] Ooh!

She's just given him a little swipe.

Got a bit too close.

She's a bit uncertain.

Pfft!

There's really not much aggression here, though.

This is really strange.

He's going back to her.

He's going back.

[ Tiger growls ] Ooh.

Wow!

She just whipped round and showed her belly to him.

It's a sign of submission.

Huh.

They're walking together.

They do seem more tolerant of each other than I would expect.

There's definitely some kind of relationship here.

-Adult tigers rarely spend time with each other outside of mating, but filming at night is giving the team new insights.

From the thermal drone, at least one of Bandheil's motives for sticking with Goma is becoming clear.

A free meal.

♪♪ Giving away some of her food is a small price to pay to keep the peace.

With so many tigers on the island, it may be a strategy to avoid conflict.

-There is some kind of driving force behind this behavior.

Having smaller ranges that they've been forced into, maybe it's forcing tigers to work more together.

The only way to survive, the only way to eke out a life is by being more cooperative.

♪♪ [ Birds chirping ] -As the team heads out to check on the mother tigers and their cubs, there's an unexpected visitor joining them.

[ Tiger growls ] -Just arrived at drone base to set up, but we've got a wild elephant on the horizon that is getting closer and closer.

I'm not sure if it's bothered by us, but quite often elephants will use diversion techniques like pretending to eat whilst watching you.

Yeah, there is some flapping of ears, which is showing signs of aggression.

And it is coming towards us.

I think it might be time to start retreating.

♪♪ -He's close enough that if he starts running towards us he'll be here in no time, so let's go, Sameer, sir.

Zam zam, zam, zam.

[ Engine starts ] ♪♪ -Giving the elephant a wide berth, the team moves down river.

[ Birds chirping ] Sushila and Dan are joining Manju, tracking Mala.

With Lauti disrupting her hunts, Mala has yet to find them a meal.

-Mm, the cub looks restless, right?

-Yeah.

-Hungry.

-Oh, yeah.

-Yeah.

-It's the perfect target for Lauti to practice stalking.

-Cub's creeping.

-Stay low.

Use the cover.

And...pounce!

-All: Oh!

[ Laughter ] -Yeah.

-[ Chuckles ] -The cub tries to hunt, realized mum's not watching, and is like, "What?

You didn't see?"

-Lauti is taking her first steps towards becoming a successful hunter.

But right now, the most important thing she can do is let her mother take the lead.

And Mala has just spotted an opportunity.

-[ Whispering ] Mala is moving straight towards some deer.

♪♪ It looks like she's just told Lauti to go, to go away basically.

It's going out in the opposite direction.

So Mala must have communicated really subtly to Lauti to just go away, to make itself scarce.

♪♪ Oh, she is meters away.

♪♪ ♪♪ Oh, my gosh.

-She's got a kill.

-She's got a kill!

It is a small meal, but, ah, such a relief.

Mala and Lauti finally have something to eat.

[ Cub growls ] Lauti is just so impatient.

[ Cub growls ] And Mala's just swinging it around, going, "No, no, no, no, no, be patient, be patient."

Lauti is wrestling with the kill.

-Lauti has demonstrated she can stay hidden while Mala is hunting, making it easier for Mala to provide for them both.

-I do feel like, the way in which they communicated, it seems like she's learning, like she knows when it should go away, when it's not needed, when mum is on the hunt.

And stumbled its way around the side of those deer, probably distracted them, and then that created the perfect diversion for Mala to come straight in.

You could see that as them working together.

♪♪ [ Crickets chirping ] -To the south, close to the team's camp, Bandheil is once again on the move.

Anna is investigating.

-[ Whispering ] Ah, he's going up, and he's going into the forest.

Max, Bandheil is moving straight towards where Goma and the cubs are.

-He seems determined to track the family down.

-[ Whispering ] Oh.

There he is.

♪♪ He's checking out her scent, exactly where Goma's been marking.

He's just trailing this family.

Literally, they're just there, right under the drone.

I just hope Goma takes her cubs away.

Is she gonna try and have a standoff?

What's going on?

♪♪ [ Tiger growls ] [ Whispering ] Oh, wow.

The cub's greeting him.

And now Goma has rubbed up against him.

This is a male with the whole family.

[ Tiger growling ] This shouldn't happen.

Everything we know about tigers says that they're solitary, especially the males.

They roam huge territories and have cubs with several mothers.

They're not supposed to have anything to do with the cubs.

The females are not supposed to let them anywhere near the cubs.

This is absolutely mind-blowing.

[ Radio beeps ] Hey, Dan, did you see all that play out on your screen?

-Yeah.

Absolutely hair-raising and totally new.

They're one of the most secretive animals in the world, and what we know about them is so limited because we've never been able to follow them like this.

We've been able to uncover something that maybe happens with more tigers than we realize.

-To see them interacting together as a family suggests that these cats are far more social than we ever imagined.

She's now moving away, and the cubs have gone back to Bandheil.

She trusts him so much, she's left him with the cubs.

Maybe these males play a bigger part in the lives of the cubs.

Tiger Island is just rewriting what we know about tigers.

♪♪ [ Insects chirping ] [ Birds chirping ] [ Tiger growling ] -With Bandheil offering fatherly protection, the future of the cubs is more secure.

-Bandheil's presence here is key for Goma in terms of her cubs' survival.

It means that other males are unlikely to try and muscle in on Bandheil's territory.

[ Tiger growling ] -Over the next year, the cubs will grow to independence, the biggest step in their young lives.

-It's gonna be lots of change for these cubs.

Goma's cubs -- they'll have to branch away and get a territory of their own, and that's gonna be fascinating.

Mala is doing incredibly well as a first-time mum, and Lauti is getting more independent.

-These tigers are showing us they perhaps aren't the solitary big cats we believed they were.

-They are so much more complex, so much more social than we ever thought possible.

-On this remarkable island, tigresses are looking after each other's cubs... ...and sharing food with males, while fathers are playing a role in family life.

-You think with the biggest cat in the world that there's likely not that much left to find, and then you come here and it changes everything.

(upbeat music) ♪ Ah, hey ♪ (upbeat music continues) -This program is available with PBS Passport and on Amazon Prime Video.

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

♪♪