[ 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.

-[ Growls ] -These secretive big cats are notoriously difficult to film.

-[ 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... capturing their hidden lives... -There are five cubs.

No one has ever seen tigers do this before.

-One of the cubs just rocked up with something fluffy in its mouth.

-...close encounters, and greatest dangers.

[ Growling ] -I think we need to back away.

This is a slightly dangerous situation.

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

It's winter and the dry season.

Cooler temperatures mean tigers are more active, making this the ideal time for tracking them.

♪♪ As they enter tiger territory, wildlife guide Sushila gives big-cat biologist Dan a safety briefing.

♪♪ -If we're walking today and we come across a tiger with cubs or a rhino or an elephant that's showing aggression, what tools do we have to protect ourselves?

-We have two different things.

-Flares won't harm a tiger, but they should scare it off -- a potential life-saver for the team.

-You really have to have a healthy respect for walking here on foot and you can't forget that they're apex predators, largest cats in the world, and they have evolved.

They specialize in hunting animals much, much bigger than us.

And it is by choice that they don't take us.

Because right now, there's probably a tiger that's at least aware of where we are.

♪♪ You see how fresh that is?

Look at that.

That couldn't have been more than a few hours ago.

-An experienced tigress named Goma lives in this area.

She has two cubs, but the team are yet to spot them.

Dan is hoping to film them using remote cameras.

-It's so spooky in here.

♪♪ Okay, this is the spot.

They've been drinking here.

You can see the front two paws.

-Ooh!

-Yeah.

-Remote cameras provide valuable information and should help to monitor Goma and her young family.

-We need to get out of here, I think.

100 meters, deer calls, and deer calls are a really good sign that tigers are there.

♪♪ -Dan, Dan, we've got Goma.

She's heading in your direction.

-Okay.

Yeah, I can see the drone right in front of me.

[ Drone buzzing ] [Whispering] She's right there.

I think she's gonna cross the road.

-She's on the road, Dan.

She's on the road.

-She's on the road.

I can see her.

I can see her.

♪♪ She's really close.

♪♪ ♪♪ [ Breathes deeply ] ♪♪ That was incredible.

She was so close to me.

She's so much bigger than I thought she'd be.

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

-[ Growling ] The reason this is so important, I think -- it just shows that tigers aren't interested in us.

They don't want to hunt us.

She doesn't see us as prey.

And being that close to her on the ground, it just feels really good to be able to prove that, because people just have this idea about them.

They think that they're predators that only want to attack and want to kill.

She just wants to live her life.

♪♪ -Tigers typically prefer to avoid contact with humans... but attacks do happen.

In this region alone, over 30 people were killed by tigers in a recent five-year period.

Most victims are alone and bent over while gathering food.

Attacks on people may be the result of mistaken identity... since, in most cases, the tigers don't eat their victims.

Goma's territory borders several villages, and locals are allowed to bring their livestock here to graze.

[ Mooing ] -Do you think they -- Are they worried?

Yeah.

I mean, they're used to it.

It's such a strange feeling being so close to an adult female tiger.

You're told you shouldn't be that close to an animal like that.

And they have this every day.

-Mm-hmm.

-To the west, in the neighboring territory, lives Goma's daughter, Mala.

At 4 years old, she's a mature, independent adult.

Cinematographer Anna and Sushila's sister Manju are following her.

-[ Laughs ] -Mala is raising her first litter.

-This is absolutely beautiful.

-Her cubs are just 3 months old.

-I wasn't sure if they were weaned yet, but clearly not.

They're still suckling from mom, so they've still got a long way to go.

We've got a tiger-cub pile-on here.

And they have got the milk zoomies.

-Tiger cubs stay with their mother for up to two years... relying on her for everything until they can fend for themselves.

-One of the cubs just rocked up with something fluffy in its mouth, and it looks like a deer tail.

So they've definitely got a taste for meat already.

That is clear.

But at the moment, it seems to be more of just like a plaything for them.

-Only half of tiger cubs make it to adulthood.

[ Snarling, growling ] It's going to be a challenge for Mala to keep her boisterous cubs hidden away and safe.

♪♪ [ Birds chirping ] Dan and Sushila are checking the remote cameras for any sign of Goma's cubs.

-Okay.

13 clips.

It's too foggy to see that one.

I can't see.

Okay.

[ Gasps ] -Ooh!

-Oh, my gosh.

-That's the big -- -That's a male, right?

-Yeah, that's a male.

-That's interesting.

-Yeah.

-Oh, he's huge.

-Yeah, huge.

-[ Sniffing ] -Do you know who he is?

-Um... Okay.

If this male has moved into this territory and it's not the cubs' father, those cubs are in major trouble.

♪♪ -Male tigers will kill cubs that aren't their own.

♪♪ Now on alert, Anna and the drone team are tracking Goma.

Cinematographer Max is hoping she'll lead him to her cubs.

-There's a tiger right there.

Tiger right there.

-[ Growling ] -[Whispering] That's Goma just there.

Okay, she's looking right at us.

She knows we're here.

[ Growling ] Look at the size of those shoulder blades.

-Goma likely weighs over 350 pounds, yet she'd be no match for a mature male -- one and a half times heavier.

-To see her this close at ground level... you realize that these really are the biggest cats on the planet.

♪♪ She's the queen of this island and she knows it.

♪♪ -To maintain her status as the owner of this area... Goma must mark her territory frequently.

It's a message to other tigers to stay away.

And this is why.

Her two cubs.

At 9 months old, they're bigger and stronger than Mala's cubs, but still entirely reliant on Goma.

Goma's priority is finding enough food for these two rapidly growing cubs.

And Manju has just captured her hunting.

-She's moving so slowly.

-Yeah.

She definitely knows exactly where to move and where to walk so that deer can't hear her.

It's amazing seeing her go through the grass like that.

She looks like a snake from above.

♪♪ ♪♪ And I love the way she's just walking a few steps, stopping, and then she's looking out, looking out.

♪♪ ♪♪ ♪♪ -Whoa!

-Whoa!

-That was a really big chase.

-Yeah.

-I wasn't expecting her to run so far.

♪♪ She knew what the weak point was and she just went for that, and you could just see her tail was going "whoof-whoof-whoof."

It was just moving in so many different directions to keep her zigzagging.

Oh, she's got it.

Mm!

♪♪ [ Laughs ] Didn't even say "Thank you."

-Yeah.

[ Both laugh ] [ Snarling ] -With one cub dominating, the other is missing out on this meal.

-If one of the cubs is more greedy than the other, it could actually be quite a big problem for Goma, because this other cub needs just as much energy, and if it's not getting it, then there's a possibility it won't survive.

-A fawn is barely a meal for three tigers.

Goma needs to catch bigger prey to ensure that both her cubs get enough to eat.

But in order to hunt, she must leave them alone, even though a male is on the prowl.

Following Goma upriver, Max is joined by Sushila and Dan.

-There, there, there, there, there, there, there, there!

She's in there.

She's in there.

-Where?

Where?

Where?

Shh, shh.

Just tell me where.

-There.

-Oh, she's up in the woods.

I think we can creep to this corner and see if she has a go for these deer.

What do you think?

Yeah?

-Moving slowly, okay?

-Yeah, yeah.

You don't want to scare the deer.

-Is she going to -- Can everyone watch that?

-Yeah, I'm watching it.

I've got eyes on it.

-Yeah.

Do the other side.

-Which side?

Who's running?

-All the deer.

-Anyone see a tiger?

-Yeah, I've got eyes.

There's no tiger yet.

-Ooh!

Ooh!

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

-Film!

Tiger!

Tiger hunt!

-Oh!

-She's there, she's there.

-Wow!

[ Laughter ] -So good.

So good.

-Wow.

It's complete chaos.

She just suddenly burst across this river and went for a deer.

It was a miss, but the deer have now scattered.

She's in the long grass.

But wow.

I don't think you ever see -- Where?

Where?

Where?

-Another tiger in the water.

Another tiger.

Look, look.

-Where?

In the river.

-I think it's the male.

-Yeah.

♪♪ ♪♪ -That's the biggest danger for young tiger cubs is males like that, because in order for him to take over this territory, which is maybe what he's trying to do, he has to kill her cubs if they're going to mate.

♪♪ -As night falls, the team are forced to leave Goma with the male in pursuit.

[ Insects chirping ] [ Birds chirping ] Keen to find out what happened overnight, Max is back on Goma's trail.

She's alone and seemingly distressed.

-[ Roars ] -Goma has been on a mission, moving around the whole of the island.

-[ Roars ] -She's calling nonstop.

-[ Roars ] -Goma's calls suggest she's searching for her cubs.

-Keep going.

Oh, there she is.

Stop, stop, stop, stop, stop.

She's just there.

Now just don't move too much, mate.

She's really just there.

See?

Do you see?

-What is clear -- Goma has noticed Max.

-[ Growls ] -No, no, no, no, no, no.

Stay still, stay still.

Stay still.

♪♪ -Goma's agitation is likely due to the presence of the male... spooking her and her young family.

♪♪ One of her cubs has been seen crossing the river... -She's approaching the road.

-...and is now close to the village.

Goma needs to get the cub back to the island, but a desperate mother tiger could be dangerous.

-[ Shouts indistinctly ] -[ Laughs ] -She is parallel with the... You should hold your position, and then they're likely to cross back onto Tiger Island.

♪♪ -A bit worried.

Tiger Island's over there, and this is the village.

There's a wedding happening on this site, and all of their friends and family are there.

And perhaps that male that's been scoping out, searching for -- She's there!

She's there!

♪♪ -Goma is crossing back to her territory on the island.

-Still no sign of the cub.

I think she's been spooked by that male.

-[ Roars ] -I can hear her contact-calling.

[ Imitates roar ] Trying to get that cub away from danger, all the way back onto the island.

But she doesn't want to come find it again herself because she's so exposed.

-[ Roars ] -She knows there's loads of people on this side of the river.

She knows they can all see her, but she's so desperate.

This is her worst nightmare.

♪♪ This isn't tiger behavior.

They are stalk-and-ambush hunters that specialize in hiding.

Her whole evolutionary history has perfectly formed her to disappear, and she is sitting out in the open.

♪♪ [ Gasps ] Her cub's coming!

Her cub's coming across!

♪♪ Yes!

♪♪ ♪♪ Good news, guys.

Goma's cub has crossed the river back to her.

They've gone into the jungle now.

-Thank you, Dan.

-That level of parenting, how much she cared for that cub.

She was making everyone focus on her so that the cub would have space to come across by itself.

♪♪ -Concerned about Goma's other cub, Dan and Sushila are heading to the area they last saw it to check the remote cameras.

♪♪ -Mongoose.

-Oh, yeah.

♪♪ -What's this one?

Where's the other cub?

♪♪ Two cubs!

She's really filling the tank, though.

This watering hole is perfect for her.

She doesn't want to take the cubs out into the open.

She wants to hide in this tall grass.

There's one cub that took all the food the first time, remember?

Yeah.

Definitely seeing the differences between -their personalities, right?

-Yeah.

-The confident one and the shy one.

-Goma and her cubs are reunited and safe for now.

But the male is still roaming the island.

Male tigers cover big distances, crossing the territories of multiple females, trying to father as many cubs as possible.

♪♪ Here, they're more secretive than the females, possibly to avoid coming into contact with other males.

When tigers meet, fights can end in death.

Concerned about the youngest and most vulnerable cubs on the island, the team is back in Mala's territory.

-Look at here.

-Yeah, that's this.

This is mama.

It's very deep, right?

-More big -- Yeah.

More big and deeper.

-Hopefully that's Mala, right?

-Um, Mala... -Look at the distance between them.

-Yeah.

-You don't think that could be the new male?

That's not a good sign.

-A male this close means Mala's cubs are no longer safe on the island.

♪♪ Manju and Anna are heading to check on them.

-Anna, Anna, the cubs are north of Jackal Point.

♪♪ ♪♪ -The cubs might be having fun, but they're exposed and alone.

-Mala's job as a first-time mom must be so tricky here, because when she goes out hunting, she's going to have to leave these three behind, and they are clearly totally defenseless.

That's quite worrying.

They're making probably a lot of noise, from what it looks like they're doing.

If that other tiger wandered into this area, he'd probably hear them.

[ Sighs ] And now I just want to see Mala back home with them.

Now, you guys just stay safe, because mom needs to find you.

♪♪ -The rest of the team are searching for Mala.

Male tigers aren't the only threat to her vulnerable cubs.

-Just hold up here.

Look at the size of that rhino.

-With skin 1 1/2 inches thick, the greater one-horned rhinoceros weighs 10 times as much as a tiger.

-The last thing one of our mothers would want is that bull rhino going anywhere near the cubs, because a 2-ton freight train like that would just flatten anything in its path.

♪♪ -It's very relaxed.

It's not angry.

But you just don't want to push it with that animal.

Much more dangerous than a tiger.

It will charge if it feels threatened, whereas the tiger will probably just saunter off.

Rhinos -- they don't mess about.

If there's a problem, they'll just trample it.

It's looking right at me, yeah.

It's looking right at me.

It's coming this way.

Um, okay, so, if... Okay.

Just be careful, because the rhino is coming this way.

♪♪ ♪♪ I think we just stay still.

If you show panic, these animals feel panic.

But it is coming towards us.

-We need to go?

-I think we need to back away.

Yeah, I think we need to back away.

This is actually a slightly dangerous situation.

Yeah.

Just slowly move.

Because it's an incredibly fast animal.

And if it wants to, it could be with us incredibly quickly.

Okay.

Okay.

Okay.

The guides are bringing the vehicle over just to make sure the rhino walks away.

-The sound of the vehicle is enough to move the rhino away.

-I know we're going to be okay.

It's just -- Whew!

Careful.

Calm, calm, calm.

There we go.

Off you go.

Off you go.

Hair-raising.

♪♪ -To the north, another rhino is moving into the home range of a third tigress named Jugini.

The sisters suspect she may be another of Goma's adult daughters.

She has three cubs and has just made a kill, which is attracting attention.

A rhino could easily trample the cubs and seriously injure Jugini.

♪♪ ♪♪ -Oh!

-Her cubs have fled, but Jugini does not want to give up their meal.

-Oh.

-Rhinos are herbivores, but they have a powerful sense of smell and often investigate strong scents.

Pushed off the kill, Jugini and her cubs may have to go hungry.

Finding another meal this big will be challenging.

The pressure to protect and provide for cubs is relentless.

And in Mala's territory, the greatest threat a mother tiger can face has just been spotted... an adult male tiger.

-Can't work out at the moment whether he is displaying hunting behavior or he's picked up on the scent of Mala and her cubs.

-If he finds the cubs, he may try to kill them.

-His cheek ruffs are so wide.

He's got this really big, chunky neck.

He is very intimidating.

♪♪ There's a cub nearby.

Cub nearby, cub nearby.

♪♪ The cubs are within a couple of hundred meters.

And they've just scarpered, but he is hot on the scent of them.

So it turns out he wasn't hunting at all.

He were -- Well, he was hunting for cubs.

So... Where are you going?

♪♪ Oh!

There's Mala.

♪♪ [ Growling ] ♪♪ [ Gasps ] Oh, sh... -[ Growling continues ] -Ooh, ooh, ooh, ooh, ooh!

♪♪ [ Growling continues ] ♪♪ The difference in size is huge.

♪♪ [ Growling continues ] She's clearly trying to keep him away from her cubs.

[ Breathes deeply ] ♪♪ She looks like she's being entirely submissive at the moment.

She's flat on the floor, and he's sort of standing over her.

You can really see very clearly how different their body shapes are when they're this close together.

Mala is so much slimmer.

She's a lot smaller.

And her entire posture has just changed.

I've never seen her look quite like this before.

Her ears are almost pinned back.

♪♪ -The stand-off continues for several hours.

[ Growling continues ] -This big male has come in all guns blazing, but Mala has shown him that she means business.

And if he's gonna even attempt to get her cubs, he's going to have to go through her.

And at the moment, she's shown him that that is going to be a very, very difficult challenge.

What I'm worried about now is that he knows that Mala and her cubs live here.

But I'm just going to hold on to the hope that Mala has shown him that it's not worth the risk for him.

She is feisty and she will fight back for her cubs.

♪♪ I think it's going to be a sleepless night for us and definitely a sleepless night for Mala.

♪♪ [ Insects chirping ] [ Birds chirping ] Our mission for this morning was to re-locate Mala, to know that she is safe and with her cubs.

But we've just found the male from yesterday, and I currently can't see Mala around.

But he is acting really strangely, sort of pacing around.

And what he's up to is looking old.

♪♪ Looks like there's some blood just in front of him.

I don't know if he's made a kill.

Okay.

What's he got?

♪♪ [ Gasps ] Manju, that's another tiger.

-Yeah.

-Is that a cub?

-Yeah.

-No!

♪♪ Oh.

♪♪ [ Breathes deeply ] That is horrible.

Just one?

Or is there more?

-There is one more.

-There's one more?

♪♪ [ Sighs ] Oh, no.

-Have you found the other one?

-We don't know where it is.

-[ Gasps ] -He's been following her.

He found her and he thought, "I'm not letting you go until you take me to your cubs."

And he -- And she's inexperienced.

And she did.

We have to find the last one.

I hope that cub's alive.

[ Birds chirping ] -Unsure whether Mala herself has survived the male's attack, the sisters are searching her territory.

♪♪ ♪♪ ♪♪ ♪♪ ♪♪ ♪♪ -Over the next four days, the drone crew stays with Mala.

There's no sign of her third cub.

-Oh, she looks thin.

-[ Roars ] -This is awful.

-[ Roars ] -She's calling.

-Yeah, she's calling.

-Oh, that's really sad.

She must not know that -- [ Gasps ] [ Laughs ] There's a cub.

Yes!

Yes, Mala!

Yeah, she saved one.

-Yeah.

-I can't believe it.

I really can't believe it.

I was like 99.9999% sure that there was no chance that there would be another cub alive, but there is.

This cub is really scrawny, but looks pretty healthy other than that.

♪♪ ♪♪ She's really far away now.

She's gone to the other side of the island and she's just crossed over the water.

Where are you off to?

-Yeah, it's extraordinary, isn't it?

We've just managed to catch the last glimpses of Mala and this little cub before they try and find somewhere else safer to live.

If this male's taken over the area, then, yeah, she's not going to hang around with this little baby with her, is she?

-Literally kneading extra milk out.

It's a nonstop nursing.

♪♪ -After the loss of its siblings, this cub's chances may actually have improved... as Mala will now be able to give it all of her attention.

♪♪ ♪♪ [ Birds chirping ] To the east, Goma has yet to catch something big enough to feed her whole family.

And her smaller female cub especially needs a meal.

♪♪ ♪♪ -Manju and I can see some deer, and they're really not that far away from her, so I think this could be it.

♪♪ Rob, are you still over her?

-Yeah, still on her.

♪♪ -Let's see.

-Okay, so, she has just gone behind that bush there, and the deer are probably 15 meters in front of her.

So she's really -- Yeah, she's really on them now.

-She's closing in.

[ Gasps ] ♪♪ And the deer have no idea.

-Yeah.

-They really don't know that she's there.

-Oh!

-Oh, wow!

There's us.

-Just there.

-There's us in the background.

♪♪ She's staying super-low.

♪♪ ♪♪ -Oh, she's going for it!

She's going for it!

♪♪ I hope she's managed to get one.

Where... Okay, so, they ran... She did?

-Yeah, yeah, yeah.

♪♪ -Well done, Goma.

That's really big.

-Yeah.

♪♪ -Finally, both of Goma's cubs can feed properly.

Goma's hunting skills are key to her success as a mother.

Keeping her cubs well-fed means they'll both be strong.

And, soon, they'll learn to hunt alongside her.

♪♪ ♪♪ -So, Goma is clearly taking a well-needed rest.

And her cubs just sat next to her.

-But Goma's family is not alone.

-Oh!

There's three cubs.

There's three.

No way.

No.

Four.

There's four cubs.

Manju, how many cubs does Goma have?

-Two cubs.

-Okay.

[ Buzzing ] -Nearby, the drones have spotted another tiger.

It's Jugini.

Normally, mothers with cubs avoid other tigers.

But Goma appears to be looking after Jugini's cubs.

♪♪ ♪♪ -I have filmed lions before, and because lions live in a pride, they all work together and the moms help each other with parenting and looking after their cubs.

But from what I know, like, tigers are completely solitary.

So maybe because this area is so full of tigers, this is something completely new.

-Sharing parenting duties could be a response to the threat posed by males... helping to keep the cubs safe while one parent is busy.

-So, Dan, we have eyes on both Goma, as well as Jugini.

Goma has four cubs, and Jugini is on her own.

-What is happening?

-We have eyes on five cubs through Robbie's drone.

-Five cubs.

There are five cubs.

♪♪ So there are two adult female tigers with cubs... and one of them's looking after all the cubs while the other one's eating.

No one's ever seen tigers do this before.

I was about to say tigers are solitary big cats.

Are they?

[ Chuckles ] I don't know anymore.

There's supposed to be incredibly territorial.

Females do not cross paths unless they absolutely have to.

They don't share cubs.

They don't share parenting duties.

-All of this is unfolding just 50 yards over there.

This is not what it says in the textbooks.

-You just don't imagine that there's things to learn still about the most iconic animal on the planet.

But there is, and it's here.

♪♪ [ Insects chirping ] -Next time... as the heat rises... -[ Thunder crashes ] -...and the monsoon hits, -This is what these cats have to contend with all the time.

-...the cubs must learn to adapt.

-Look at them.

Wow!

-So must the team, as the tigers become more active at night... -[Whispering] She's coming towards us.

Ooh!

It's getting a bit too close for comfort.

-...and a dominant male emerges... -He is the king of Tiger Island.

-...looking to assert his authority.

-He's headed straight towards the cubs.

This is not good.

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

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

♪♪