Original subtitles

NARRATOR: By the time the Ganges reaches the last stage of her journey

across the great plains of Bengal,

she is a mighty river, over five miles across.

But now, over 1,200 miles from her birthplace in the Himalaya,

the great river begins to break apart.

The sacred waters complete their journey to the sea

through the many channels of the delta,

a magical place where the boundaries between land and water are blurred.

The delta, shared between the countries of India and Bangladesh,

is home to the most densely packed human population on Earth.

But there is also space here for some extraordinary wildlife.

Even in the 21 st century,

all living things in the delta remain at the mercy of the great river.

In just a few months, her mood swings push the countryside

from near-desert conditions

to the violent storms and floods of the monsoon.

How do people and animals survive in this place of such extremes?

Over 100 million people live along the waterways of the Ganges delta,

yet there is one last truly wild place here.

Where she meets the sea, the great river has helped form

one of the planet's greatest and strangest wildernesses.

The animals in this unique and forbidding place

are only rarely glimpsed.

The name of this mysterious forest is the Sunderbans.

It's a place where the people of the delta fear to tread.

These men have perhaps the most dangerous job in the world.

They are about to embark on a journey into the dreaded Sunderbans,

but the only protection they will take with them is the blessing of their god.

The men are Muslim, like most Bangladeshis,

so this morning they are praying to Allah before setting off.

(ALL SINGING)

Their families know they may not all return.

But these brave men are going to race each other

to try and reach the forest first.

(GUN FIRES)

It is the beginning of the collecting season

for one of the Ganges delta's most precious commodities.

For centuries, men from villages along the edge of the Sunderbans

have set out on this annual expedition

into the heart of the forest they fear.

The Sunderbans stretches along the coastline of Bangladesh and India.

It's by far the largest mangrove forest on Earth,

six times the size of Greater London.

Mangroves, with their bizarre aerial roots,

are the only trees that can cope with the salty, waterlogged conditions.

There are over 30 species of mangrove in the Sunderbans,

and the biggest rely on one tiny animal to survive.

Giant Asian honeybees feed on the nectar of the mangrove flowers

and, in the process, pollinate them.

These are the biggest honeybees in the world,

and also the most aggressive.

They will defend their enormous hive to the death against any threat.

But the precious honey in those hives is exactly what the boatman are after.

These men have pushed deep into the maze

of over 400 waterways that crisscross the forest.

They spread out to search, calling to keep in touch.

Many people have been killed by swarms of these bees.

Ten metres is the closest a man can safely approach.

(MEN SHOUTING)

The threatened bees are primed to attack,

but the honey collectors know the chink in their armour.

When the bees smell smoke,

they instinctively behave as if the forest is on fire.

As far as they're concerned, the hive is doomed to burn,

and there's no point in trying to protect it.

With the bees no longer aggressive, the men can go about their work.

A good hive can contain up to 20 kilos of honey.

This is liquid gold for these men,

but even though they are poor, they choose not to take the whole hive.

Wise collectors know that if there is to be honey here in years to come,

they should leave a section of the hive behind

so the bees don't have to rebuild from scratch.

The honey will fetch a high price,

but many men pay an even higher price for collecting it.

It's not swarms of bees that make this

one of the most dangerous jobs in the world.

The trails are crisscrossed

with the tracks of the forest's most infamous residents.

Tigers roam the Sunderbans,

and they have a well-earned reputation for attacking people.

Honey collectors are especially at risk,

because tigers rest in the dense vegetation

where the beehives are also found.

Tigers kill up to 100 people every year in this forest.

Nobody knows why so many people are killed here.

The tigers are hardly ever seen and are little understood.

The Sunderbans is unlike any other tiger habitat.

The biggest prey here, the spotted deer,

is only bite-size for a predator

that needs an average of five kilos of meat a day.

There's little fresh water here.

Some people think drinking salty water might make the tigers more aggressive.

How can tigers survive in these testing conditions?

And can anything be done to stop the man-eating?

The Sunderbans Tiger Project is going to try and find out.

This team, led by British biologist Adam Barlow

and expert tracker Mizan Rahman,

are going to radio-collar a tiger here for the first time.

They've come deep into the forest to a temporary fishing village.

The team have heard an interesting rumour.

Adam gets confirmation

that a tiger was seen a week ago in the forest nearby.

The team put out bait and find a good spot

to try and tranquilise the tiger.

Mizan disguises the hide while Adam prepares for the darting.

It's a nerve-racking prospect.

Nobody knows how a Sunderbans tiger, with its fearsome reputation,

will react when darted.

The team could be in for a long and nervous wait.

The Sunderbans is huge, but it's only a fraction of the whole delta.

In the countryside surrounding the forest,

humans are definitely the dominant animal.

And none of these humans lives very far from the waters of the Ganges.

Mohammed Jaleel is the headman of a village

near the edge of the Sunderbans

on the banks of one of the Ganges' many channels.

Like most delta-dwellers, the people of Mr Jaleel's village

use the river's waters to grow rice.

November, early winter, is a golden time in the delta,

perfect for planting the first of the year's three rice crops.

Rice paddies have replaced the natural wetlands

which once covered much of this region.

But in some places, the animals

that used to live in those wetlands still thrive

because the farmers recognise their value.

Frogs help control the insect population.

And giant apple snails eat the algae that can smother a field.

Farmers who use this natural pest control

don't have to use many chemicals in their fields.

Each paddy field is an entire ecosystem.

And there's always a predator at the top of every food chain.

Open-billed storks hunt in the rice paddies.

A healthy population of storks is a sign of healthy fields.

Perhaps for this reason, many Hindus, mostly on the Indian side of the delta,

see the storks as a sign of good luck.

When the breeding season approaches, the storks gather nesting material.

The birds nest in huge colonies of up to 10,000.

The noise can be deafening,

and some colonies are right in the middle of villages.

The good luck the birds are thought to bring

means that the local residents are happy to put up with the din.

Many of the people in the delta still retain a close connection with nature.

And these fishermen have perhaps the most intimate connection of all.

This morning, they're looking for a clue to help them find the best catch.

Find the river dolphins and you've found the fish.

But to catch the fish,

the men will enlist the help of another animal,

one of the most endearing and intelligent in the delta.

Otters have been bred in captivity for generations

and trained to help fill the fishing nets.

The men position the boat near the riverbank.

Their otters's harnesses are attached to poles

which they control with their feet.

When everything's ready, the otters are allowed to dive

and chase the fish out of their hiding places.

The boat is manoeuvred towards the bank, trapping the fish.

In a morning's work, the men can catch all the fish the boat can carry.

The otters get a constant supply of titbits,

but not enough yet to fill their bellies.

Otters hunt best when they're hungry,

but it takes expert net handling

to stop them taking too much of the catch.

Only when the fishermen have finished do the otters get their reward.

Even if the catch is poor, the otters are still well-fed.

And the baby otters are well looked after, too.

The fishermen breed their animals with otters from other villages

to prevent inbreeding.

A good young otter can cost $100, a fortune for these men.

But when you make your living from the waters, it's money well spent.

All the people of the delta rely on the Ganges waters,

but the wise old heads, like Mohammed Jaleel,

know the good times won't last for ever.

Fifty miles away, in the Sunderbans forest,

night is falling.

It's been a long stakeout, but the tiger team are in luck.

After a week-long wait, a female tiger has come to their bait.

Hungry tigers are not above eating rotten meat.

(GUN FIRES)

The team have to move fast to find the tigress.

Night falls quickly in the tropics,

and they can't be 100% sure that the tranquiliser dart has done its job.

Somewhere in the blackness is a tiger

that may or may not be on the verge of unconsciousness.

They can see the tigress, but is she on her way down?

It's a tense moment.

When they're satisfied that the tigress is fully sedated,

the team have to work fast.

While unconscious, she can't regulate her body temperature,

so the team rub her with spirit and fan her to keep her cool.

The collar weighs just one kilogram, about 1% of the tigress' bodyweight.

Studies have shown that it will have no effect on her hunting success.

Every detail about the tigress is recorded.

She's quite elderly, about 12 years old.

Her teeth are worn and one canine is missing.

The team have just a few months

before the collar automatically falls off,

to learn all that they can about this tigress.

Where she goes, what she eats and whether she encounters people.

Tigers constantly patrol a territory,

making sure there are no rival tigers on their turf.

So Adam and Mizan know

they'll have to be on the move constantly to track their tigress.

But these waterways are not a reliable means of getting around.

The creeks consist partly of seawater

so they're under the influence of the tides.

The mangroves' roots anchor the trees against the tidal pull.

It's a constantly changing environment,

but some animals are adapted to exploit it.

Strange creatures emerge from the burrows

where they've sheltered from the strong tidal currents.

Mudskippers are fish with specially adapted fins enabling them to walk.

They feed on detritus left behind by the falling waters.

Fish need water to breathe,

so the mudskippers carry a constant supply in special gill pouches

which they have to top up from time to time.

Mudskippers are not the only animals to take advantage of the mudflat buffet.

Fiddler crabs sift food particles from the mud,

leaving behind neat balls of leftovers.

The male crabs have one huge claw

to impress females and see off other males.

Mudskippers try the same trick with their brightly-coloured fins.

But sometimes intimidation is not enough to scare off rivals.

Arguments can get very heated.

But the mudskippers lack the weaponry to do each other much damage.

And besides, disputes can never last very long.

With every rising tide, the mudskippers are obliged to return to their burrows

or risk being swept away.

The height of the tide is determined

by the height of the river as well as the sea.

And as the year goes on, the river level starts to drop.

The delta is entering the dry season.

It's April and no rain has fallen since October.

Outside the Sunderbans, the farmland has turned from green to brown.

The main channels of the river are still flowing,

but now it's a long way down.

The water level had dropped six metres in as many months.

The exposed riverbanks create nesting sites for birds,

like these bank mynahs.

The river's flow is so weak

that boats can be pulled against the current.

In the fields, the farmers harvest

the last of their dry season crop of rice.

Pied starlings feast on insects disturbed by the harvesting.

But most animals have buried themselves deep underground,

or left the bone-dry fields entirely.

This is a hard time for Mohammed Jaleel and his fellow villagers.

They continue to tend their fields, but the land is parched.

The people of the village earn some money in these lean times

by digging for sand for the construction industry.

They are digging in the bed of the river itself.

Many channels in the delta region disappear completely in the dry season

because the people upstream remove so much water

for drinking and irrigation.

It's the people of the delta who bear the brunt of the thirst for water

all along the river.

Even the main channel of the great river flows only in its deepest parts.

The bed of the mighty Ganges has become a dust bowl.

Little fresh water now reaches the forest where the tigress was collared.

But the temporary fishing village here is a hive of activity.

This village is only occupied when it's hot and sunny.

Perfect for drying fish.

The seas near the Sunderbans have always been rich fishing grounds,

though these days, intense fishing is stretching them to their limit.

The need for workers is so great

that boys as young as eight are hired to sort the catch.

The stench from the village attracts wildlife from the surrounding forest.

Wild boar sneak in to snack on the drying fish.

It's such a busy time. The villagers work around the clock.

And night-time is also when the collared tigress has been the most active.

In the pitch dark,

the fishermen are collecting fresh water at the village edge.

With their weak torch,

they can't see anything in the forest around them.

Adam and Mizan have tracked the tigress closer and closer to the village.

In this dry season, the fishermen aren't the only ones

making use of their waterhole.

The team can only see the tigress with infrared spotting scopes.

Her night vision is many times better than theirs.

She's had nothing but salty water to drink for weeks before tonight.

Has that made her lose her natural wariness of people?

After drinking, the tigress heads towards the village

where the men and boys are still outside working.

In the blackness, they can't see her approaching.

But she can see them.

It seems she's on patrol.

Not hunting, but someone could trigger her predatory instincts.

Tigers usually attack people who are bending over,

presenting a smaller target.

It is pure luck that nobody is killed.

The following morning reveals just how close

the tigress came to the village huts.

But for the time being,

the tiger team don't have to worry about the fishermen's safety.

The men are leaving, not because of the tigress.

They are leaving because the weather is changing.

The men head off to their home villages outside the forest.

Brahminy kites move in to claim the scraps.

With the village deserted,

the tigress now patrols this part of her territory in daylight.

The winds strengthen every day

as the hot air above the baking land rises into the atmosphere,

sucking in moist air from over the ocean.

This is the start of the monsoon.

The next few months bring torrential rain

all across the north of the subcontinent.

And all of this rainwater ends up in the rivers of the delta.

In just a few days,

the flow of the Ganges here can increase 100 fold

till it's more than the flow of all the rivers of Western Europe combined.

In places, water levels can rise by eight metres,

transforming the landscape into a waterscape.

For most people here, floods are simply a fact of life.

But the rising waters do bring dangers.

Cobras and other poisonous snakes are driven from their hiding holes.

They now swim through the paddy fields looking for dry land,

just as the wet season crop of rice is being planted in Mr Jaleel's village.

Several thousand people are killed by snakebite every year in the delta.

Most of them during the three months of the monsoon.

The snake is just looking for somewhere to make a new home.

And the river is threatening the villagers' homes, too.

The rising waters are undercutting the banks.

A month ago, Mohammed Jaleel's village was 100 metres from the river.

Now he and his fellow villagers must move their houses quickly

before they're washed away.

Erosion can begin suddenly and without warning.

Everybody must be ready to move at a moment's notice.

Hundreds of metres of riverbank land can disappear in a single monsoon season.

The whole of Mohammed Jaleel's village must wait out the wet season

in temporary homes on the only available dry land,

along the roadside.

The monsoon is battering the Sunderbans, too.

Huge storms sweep up from the Bay of Bengal

and hammer the forest.

There are breaks in the rain, but there is no escape from the flood.

The river is so swollen

that the forest is completely inundated when the tide comes in.

Nowadays, rising sea levels caused by climate change

are causing the highest monsoon tides to be even higher,

squeezing the wildlife into ever smaller spaces.

The deer must seek out the few small areas of higher ground.

Many gather on the beach near the deserted fishing village.

But the tigress is also keeping herself dry here.

The deer would rather get their feet wet than become cat food.

The monsoon can be a punishing time,

but the people and animals of the delta need to be patient,

because when the flood waters recede, they leave behind a precious gift.

The whole of the Bengal plain is made entirely of mud,

in places, over a mile deep,

brought down over millions of years by the Ganges and its tributaries.

This huge plain is the size of Great Britain,

but it supports five times as many people

because of the extraordinary richness

brought to fisheries and fields by the river's mud.

Even in 21 st century India, one of the world's fastest-growing economies,

the life-giving river is still revered as a goddess

and worshipped in 100 festivals.

She is a capricious goddess.

The soft mud is easily cut through by the river.

Thousands of people lose their houses to riverbank erosion every year.

But even for the people made homeless, like Mohammed Jaleel,

there is a ray of hope.

The Ganges gives as well as taking away.

Wherever the river is cutting away mud on one side of its channel,

it is depositing it on the other.

Little by little, the mud forms either new river bank,

or even little river islands.

Over the years, the islands grow.

And in time, they can be settled and cultivated.

People who have lost their land

will take advantage of any new farmland that becomes available,

no matter how small.

The rivers that feed the Ganges carry twice as much mud as the Amazon

to the delta every year.

The mud can be seen billowing out to sea for over 100 miles.

In the Sunderbans, the mangrove roots trap and hold the mud.

This is a much more productive place than it might appear at first sight.

Over 300 species of birds,

including Lesser adjutant storks and Indian pond herons,

exploit the richness of the mud flats.

And nine species of kingfishers fish in these creeks.

Nearly 50 species of reptiles patrol the waterways,

including saltwater crocodiles and giant water monitors.

The mud feeds the mangroves that are the basis for everything here.

Some animals, like macaques, eat the mangrove roots.

Others, like the spotted deer, eat the leaves.

This forest, surprisingly, supports thousands of deer and wild boar,

and that has exciting implications.

There may be enough food here to support lots of tigers.

So much food, perhaps,

that it seems some tigers don't need to hunt prey that walks right into them.

(BOAR GRUNTING)

Early indications from the tiger team's work

suggest that the Sunderbans might have

the greatest concentration of tigers in the world.

Maybe over 300 animals.

These tigers need protecting.

But so do the people.

It's too early to say if the unique conditions here

make these tigers more aggressive.

But one thing is clear, many people who come into the Sunderbans

don't know how to behave in tiger country.

The tiger team are trying to make people think about safety.

"Don't go into the forest alone and don't work at night."

The fishermen, back in the village after the rains,

are building a cage around the waterhole

to discourage further visits from the tigress.

Protecting all the thousands who come into the Sunderbans every year

to catch fish, cut wood, or gather honey will be a difficult task.

But strangely,

these livelihoods are only possible because of the tigers.

Fear of the big cats means

that only the bravest venture into the Sunderbans.

Without the tigers, the forest would soon be overrun,

and the natural bounty it provides would be lost.

In the Sunderbans, as all along the Ganges,

all living things depend on the great river's richness.

On her epic journey from the mountains,

she brings fertile mud and life-giving waters

to fields and forests.

The Ganges has fuelled the rise of great civilisations,

and today supports nearly one tenth of the world's population.

But what does the future hold for this river of life

and the lands she has created?

By the end of this century,

over 10% of the delta might disappear beneath the sea

because of climate change.

The river itself is also threatened.

If the growing population continues to swallow the river's waters

at the current rate,

then some day, the Ganges may no longer reach the delta.

There is hope for the future of the great river,

and it's embodied within the reverence with which she is still held.

Sagar Island is the last land before the Ganges joins the sea.

Every January, over a million Hindu pilgrims gather here

to give thanks to the river.

They bathe at dawn on the holy day of Maker Sankranti,

hoping that the sacred waters will wash their sins away

into the Bay of Bengal.

People know that the Ganges is the giver of life here.

Hopefully, they will fight to keep their goddess, Ma Ganga, alive and well.

The future of the river and the life she sustains

is in the hands of mankind.