Original subtitles

I've spent much of my working life

trying to film big cats.

I've watched them in the wild and analyzed the footage

in the editing room,

which has given me a real insight into their behavior.

Today, we can see these amazing predators on our screens

any time we choose.

(dramatic music)

But until quite recently,

we knew practically nothing about them.

Big cats are normally shy, and very secretive.

Today, their populations are shrinking fast,

but now we have the means to view them

in more detail than ever,

(thunder rumbles)

and learn the intricacies of their lives.

Which is just as well, because we need to find ways

of living alongside them

before they disappear forever.

(birds chirping)

The largest of all the big cats,

and perhaps the rarest, the tiger.

This animal has almost completely disappeared

from its former range.

We've barely had the chance to discover it at all.

(tense music)

Modern technology gives us the opportunity

to reveal the real tiger,

before it's too late.

We often think of the tiger

as a creature of tropical forests,

but actually, its true home may well be in colder climes.

In historic times, the tiger's range was vast,

covering much of Asia.

They were commonly found from the Russian Far East

all the way to Turkey.

Today, only 500 or so of these Siberian tigers survive

in the Amur region of Russia.

(bird squawks)

And at over 250 kilos, a quarter of a ton,

this tiger subspecies is the largest of all cats.

(tiger growls)

And with its luxuriant fur coat,

it can withstand some of the coldest weather on Earth.

Like other members of the cat family,

tigers get their phenomenal strength from special muscle

known as very fast-twitch muscle.

But the tiger also has more endurance muscle

than the other big cats, so can sustain a long chase.

(tiger growling)

Which is just as well.

Here, much of the tiger's original prey has been hunted out.

Eurasian elk and other deer only survive in low densities.

Finding a meal requires extreme stealth

and literally superhuman power.

Today, Amur tigers inhabit an area

of some 40,000 square miles,

which works out at about 200 square kilometers per tiger.

Just 200 years ago,

there were hundreds of thousands of tigers in the world.

Over the last century,

they've experienced an almost total population crash,

and at least 97% of those tigers have gone.

Today, just under 4,000 remain.

But not all of these tigers live as thinly spread

as the Amur tigers.

In the Terai Arc of India and Nepal,

a few fragments of the tiger's original

tall grassland habitat

support the densest populations of tigers.

And they share these tall grass savannas

with some of the most endangered wildlife on the planet.

This habitat is very good, like a mosaic habitat.

They have grass, it is a grass jungle.

Tall grass and water.

This is a very good habitat for tigers.

The few fragments of the Terai that still survive

contain some of the most diverse habitats in Asia.

A mixture of grasses, scrub, forest, swamp forest, and river

creates a richness and intensity of life

that has all but disappeared.

(birds calling)

While these savannas may harbor

the densest populations of tigers in the world,

it isn't where most tiger films are made,

for one very good reason.

It's almost impossible to see tigers here at all.

Grass and other thick vegetation obscures almost everything.

Only the very biggest animals are visible.

Wild water buffalo, the largest of all buffalo,

are rarer even than tigers.

At over a ton in weight, with huge, tiger-ready horns,

these would be a daunting prospect

for the biggest of all cats.

Even more massive than the buffalo are gaur,

the closest wild relative of the extinct aurochs

that tigers once hunted in the north.

At over two meters high at the shoulder,

and 50% heavier than even the American bison,

they dwarf domestic cattle.

And yet, wherever gaur are found,

they are definitely on the tiger's menu.

I'm always amazed by the sheer audacity

of cat hunting behavior.

They frequently tackle prey many times their own weight,

with no apparent concern for their safety.

(birds chirping)

The gaur's height gives him a good view over the grass.

(tense music)

But once the herd panics, the tiger can take its pick.

This isn't an animal that a lion could tackle on its own.

(gaur bellows)

And yet this tiger has brought down an animal

six times her weight,

and then drags it, using only her teeth.

(gaurs bellowing)

Despite the tiger's incredible strength,

there are animals in the Terai they should fear.

(elephants trumpeting)

Elephants can be a bit of a problem,

(elephants trumpeting)

terrorizing tigers whenever they meet them.

(growling)

(trumpeting)

The Terai is also where the world's last

Asian one-horned rhino live.

Once these animals were found over much

of South and Southeast Asia.

Now they exist only in a few reserves.

But in the grasslands of the Terai,

the rhino could be critical to the survival of tigers.

At first, I thought it must be coincidence

that the densest population of tigers in the world

are all in areas that are inhabited by rhino.

It seems an odd connection,

since tigers only rarely kill rhino,

but these are creatures of habit.

They like to use exactly the same routes every day,

making neat, wide paths as they go.

(tribal music)

So wherever there are rhino,

and elephants, which widen the roads,

(elephant trumpets)

all the wildlife can move through

dense grassland unhindered.

Tiger footprints are frequently found on these rhino roads.

The resulting network is as complex as any city,

and just like in a city, if a tiger remembers a route,

it can move quickly and efficiently from A to B.

The combination of the trail-making megafauna,

along with regular flooding, which brings extra nutrients,

allows this habitat to support large herds

of potential tiger prey.

(tense music)

For me, this is tiger country,

where the world's biggest cats

are living among some of the most dangerous

and aggressive animals on Earth.

It's a real privilege to spend time

in this almost-extinct wildlife community,

looking for the tiger mother

and her two almost full-grown cubs

I was told were in the area.

In the dry season, the grass is shortest,

and gives me the best chance of seeing a big cat.

In this small corner of Bardia, there are so many tigers,

they have just five square kilometers per cat,

and are surviving on a fraction of the land area

needed by their Russian cousins.

But it doesn't mean they're easy to see.

Waiting for days on a likely riverbank

normally reveals an extraordinary parade

of potential tiger prey, and very few tigers.

Spotted deer are the most numerous grazer here by far.

And they're often joined by the critically endangered

swamp deer, or barasingha.

Rhinos would make scarily close passes,

and their visits,

along with the antics of the smooth-coated otters

kept me awake during the long stints in the heat.

When not in the water,

the otters love a bit of croc-bothering.

(birds chirping)

(crocodile growls)

But tiger sightings were few and far between,

and often too far away to see whether it was

a tiger just passing through,

or one of the three I was looking for.

Days would pass between visits.

When a tiger did show itself,

the pattern was usually the same.

The sound of distant alarm calls of spotted deer

would alert the other animals.

Almost invisibly in the grass,

a tiger was moving towards the water.

(tense music)

The animals would react, and clear the area

(animals screeching)

before the tiger would suddenly appear on the bank.

This looked like a young female,

so was, perhaps, one of the family I was looking for.

A young bull elephant paid no attention whatsoever.

(tiger growls)

But she still gave him a warning, just in case.

So far, I've not seen any sign of hunting

or a mother with two large cubs.

But when all's settled down,

this cat immediately goes into stalking mode.

And there's another tiger!

The otters start to get nervous.

(otters squeaking)

The first tiger knows there's something there, and hides.

And now the second tiger appears, also a young female.

Hearing a sound behind the tuft of grass,

the second tiger stalks in for a closer look.

(tigers growling)

She gets a big surprise.

These can only be two young sisters,

as they clearly know each other.

I called them Sister One and Sister Two.

Their cuddly days seem to be over.

No sign of their mother, though.

Perhaps she's already left them.

This tantalizing glimpse is soon cut short by thick grass,

as Sister One follows Sister Two down a hidden rhino trail.

At ground level, the grass is impenetrable.

From the air, the very same grass becomes transparent.

Luckily, in Bardia, there are a few 20-meter towers

built for surveying the wildlife

and guarding against poachers.

They offer a perfect vantage point

to see what the sisters are getting up to.

There's Sister Two, with her pride back, after some deer.

Now we can see more than she can.

Those deer in the open are safe.

Those in the grass could be in trouble.

However, I'm told this youngster is only 26 months old,

so is probably a novice

when it comes to stealth and patience.

Even though the deer are running close to her,

they don't know exactly where she is.

And the tiger can't see exactly where the deer are.

She has to rely on hearing.

(birds chirping)

(deer yelping)

There are so many tigers in close proximity

that those in nearby territories

can hear what's going on with their neighbors.

Not far away, an adult female listens to the mayhem

caused by Sister Two.

(deer yelping)

(birds chirping)

On the other side of the tower,

we spot a distant male watching and listening.

We wanted to film tigers at night.

India forbids all filming at night to tigers,

but Bardia, which is just down the road

from Chitwan in Nepal,

they said they would let us try and film tigers at night.

Despite the fact that most tigers are nocturnal,

they've never been filmed at night before.

So this is a bit of an experiment.

As dusk falls, now rhinos venture into the open

for the best grazing.

They follow their trails

to favorite nighttime feeding grounds.

Oh wow, he just really sprayed that.

By 7:00 p.m., the waxing moon is now the only illumination

over the grasslands.

This is where the new technology comes in.

We have a supersensitive starlight camera,

which can see in moonlight perhaps as well as a tiger.

We also have a thermal camera which detects the heat

from animal bodies.

A group of deer have gathered where the grass is short,

and where they can see what's going on.

The rhinos seem nervous.

It's surprising these three-ton giants

would be worried about tigers.

They have skin two inches thick,

as well as special sharp teeth for fighting,

but they're clearly upset about something.

And suddenly, there's a tiger on the road.

It's Sister Two again.

(deer yelping)

The deer can see her perfectly well.

To my knowledge, this is the first time

a tiger has ever been filmed in moonlight.

(deer yelping) (tense music)

She makes her way towards the sound on a small deer track.

At her eye level, she can barely see the deer,

but of course she can hear them.

The deer can just see her.

Their heads are higher.

We also have amazing high-resolution camera traps

placed on various trails around the tower.

The deer seem surprisingly relaxed.

Now the tiger turns onto a rhino trail

in a gully out of sight.

She ups her pace to cover some ground quickly.

When she emerges at the other end,

it's as if the deer were expecting her.

(deer yelping)

In typical cat fashion, she pretends she wasn't even

looking their way, and continues.

(deer yelping)

It's hard to tell whether this was a serious attempt

or just a cub practicing its moves.

Not so much a failure as good experience gained.

Once the moon sets, it becomes very dark.

Most humans would describe this as a pitch black night,

where you can barely see the ground under your feet.

(crickets chirping)

The deer become nervous,

and concentrate into the most open areas,

with the shortest grass.

It's now too dark to see anything

without thermal or infrared.

The rhinos use scent to navigate

to their favorite grazing areas.

And there's sister number one,

walking the same route as sister number two earlier.

(deer yelping)

Finally, the cubs' mother makes an appearance

on the trap cam,

perhaps hoping for a bit of quiet hunting time on her own.

Now it was truly dark, there seemed to be tigers everywhere.

This is a big male,

who seems to be trailing the mother.

Like all the tigers we saw at night,

he walks carefully and slowly.

(tense music)

The mother can hear rhinos feeding in the river,

and changes her course to avoid bumping into them.

The male follows.

Sister number two's not far away,

trying to sneak up on some sleeping deer,

although she has no idea exactly where they are,

and is soon discovered.

(deer yelping)

500 meters away on the other side of the tower,

sister number one is looking for a lead.

Again, that slow, listening walk.

Watch the way she holds her head still,

as if she's not using her eyes at all,

but concentrating on what she can hear,

(deer yelping)

like some deer crossing the stream.

She makes her way towards them silently,

using a detailed mental map of hundreds of trails.

Like the deer, she crosses in a place

that crocodiles rarely use.

Tigers have the biggest brains of all the cats,

perhaps to remember complex routes.

(deer yelping)

The deer calls are from the other side of the river.

There's definitely another tiger moving around nearby.

It's a good distraction for sister number one,

so she can cover some ground quickly,

but she should take care.

Meeting another tiger could be dangerous.

Now she's on a clean rhino road.

She can move silently.

(tense music)

She's actually looking quite well-fed,

and probably isn't that hungry, but at her age,

hunting like this is everything she wants to do.

She's like a student revising for her exams,

and soon she won't have her mother's safety net.

Now that she's not on a trail,

any slight mistake could reveal her presence.

Her hearing is so acute,

she knows what the deer are doing,

but they're looking the wrong way.

She feels the ground as she puts her feet down.

This stage of a tiger hunt is rarely filmed,

as normally the tiger would be completely invisible.

It's now so quiet that even the echo of her own footprints

would give her information about her surroundings.

(birds chirping)

She's definitely got the hang of silent stalking.

With so many tigers around, the deer are alert.

(deer yelping)

The deer call is not for her.

She backs off rather than reveal herself,

and gives us a look, as if we're somehow to blame.

(deer yelping)

She needs to lie low for a while.

The big male is still looking for the mother.

And now, he's found Sister Two.

She's the one running for her life.

He wouldn't want to see any cubs around

if he's chatting up the mother,

especially if they aren't his.

(deer yelping)

He continues on the trail of the mother.

Sister One finds a safe place to hide.

And there's the mother.

(tiger grunts)

The male makes a small grunt to announce his presence.

She knows who it is, anyway.

She looks as if she was expecting him.

In, well, three weeks we've been here now,

we've definitely brought something new to the table

of tiger imagery, tiger story, tiger behavior.

I don't think anyone's ever been able to observe

tigers at night as we have done in the last few weeks,

and we've filmed some fantastic tigers in moonlight

and we got some good infrared behavior,

and we got some really nice two shots of tigers,

where we can see the tiger looking for the prey,

and it can't see the prey,

but the prey can see the tiger and is all alarming.

The sisters are unsure where they can go now,

and it does look as if they'll soon have to leave.

Their desire for a territory of their own

will gradually drive them apart.

From what I've seen,

they probably do have the skills they need,

but from here, their options are limited.

For one last moment, they're together,

investigating the camera trap.

(tiger growls)

The other extraordinary thing about this place,

the densest population of tigers in the world

is two kilometers from a village,

I can see its lights dropping just over there, in fact.

We've had wedding season, so they have parties,

they have very loud discotheques.

Incredibly, all this has taken place

close to a growing village

in what was recently a buffer zone.

As it turns out, this rich corner of Bardia

is hemmed in on two sides by villages and farmland.

This perfect tiger habitat, now so close to extinction,

is also perfect for agriculture.

This part of Bardia is where most rhinos live,

and where most of the deer live,

(deer yelping)

and where the densest population

of tigers in the world lives.

The mother of the two cubs won't relinquish

her hard-won territory, even for her daughters,

and she'll soon have another litter on the way.

For sister number one, this is the only habitat she knows.

Her chances of survival for another year are slim at best.

(tense music)

Most of Bardia consists of area with low prey density,

south forest, or closed hill forest.

There are only a few other reserves

where this habitat can still be found,

complete with their prehistoric megafauna.

Tiger heaven.

Good tiger habitat with tigers

is far more endangered than the Amazon rainforest

or coral reefs.

Yet in the north, there are still huge areas

that recently supported Amur tigers,

and could do so again.

(dramatic music)

For the two sisters at the start of their journeys,

we can only hope they have sufficient brains,

hunting skills, and luck

to find a place of their own.