Original subtitles

(ELEPHANT SNARLS)

Across the planet...

(SNARLS)

..there are giants...

..creatures that have pushed their bodies...

(GROWLS)

..to the limits.

In this series, I'm on a mission to find some of the biggest animals on the planet

and discover why, in the natural world,

size really matters.

Travelling to Asia...

Just look at the size of that thing!

..the Americas...

..and Africa...

Whoa! Look at that power! I didn't even spot him.

..I'll show the surprising ways

animals use bulk...

to survive.

And stepping back in time...

..I'll also meet the prehistoric monsters...

..that once roamed the earth. (SNARLS)

Today many of our big animals are in trouble.

From plastics in our oceans...

..to climate change.

It's often the biggest creatures...

..that are hardest hit.

In this episode, I'm in Africa...

..to explore the challenges...

..faced by our megafauna.

I'll reveal why the biggest animals...

..are also the most fragile.

Prepare to meet the big beasts - the Last of the Giants.

My journey begins off the southern tip of Africa...

..where I'm searching for a giant of legendary proportions.

This is the meeting point of two great oceans.

On one side is the Atlantic,

and on the other is the Indian Ocean.

Now these cold, nutrient-filled waters

are home to an extraordinary diversity of marine life,

including the biggest predatory shark on the planet.

The great white shark.

Six metres long, they launch from the water

like a jagged tooth missile.

Their jaws pack the most powerful bite

in the animal kingdom.

And their gigantic bodies can weigh more than a tonne.

I'm joining a team of shark experts and dive specialists

to see these apex predators in action.

We're heading six kilometres off the coast towards a rocky outcrop...

..Seal Island.

Covering five acres, it's packed with over 60,000 Cape fur seals.

Every autumn, females give birth to their pups.

This seasonal abundance of young seals attracts huge sharks

from thousands of kilometres away.

(HOOTS)

Seals are agile swimmers.

To catch them, great whites have become ambush hunters.

Blood-red water is the tell-tale sign of a kill.

With the sharks hunting nearby,

this is my chance to enter their world.

Right, let's do this.

Time to get into the water.

The first thing I notice...

..is how poor the visibility is -

ideal conditions for ambushing prey.

This is absolutely incredible.

I'm finally in the world of the great white shark.

And everywhere I look around me,

all I can see...is murky water.

It is quite scary

because you have no idea where the predator's coming from.

Whoa! Look at that power! I didn't even spot him.

That's exactly what I'm talking about.

I was completely unprepared.

Here it comes again. Whoa! Whoa! Look at him!

Right next to me.

Oh, my God!

It's like the size of a car.

This shark is around three metres long.

And it's this size that helps him to hunt

in these surprisingly cold waters.

The great white shark can survive in waters

as cold as 3.5 Celsius.

That's pretty much near freezing point.

And he can do that through something called thermal inertia.

The actual size of the bulk, the mass of the shark,

means that it can conserve lots of heat energy,

whereas smaller animals find it difficult to maintain their temperature.

As well as thermal inertia,

white sharks are also able to generate their own body heat.

It's this winning combination of size and body temperature

that allows them to keep their muscles warm

and explode into action.

There are nearly 500 different species of shark.

Great whites are the biggest to actively hunt down their prey.

But compared to their prehistoric cousins,

they are small fry.

Three times the size of the great white shark,

the megalodon weighed over 100 tonnes.

They ruled the oceans for nearly 20 million years,

hunting prehistoric whales.

Their immense jaws opened over four metres wide,

big enough to swallow an elephant whole.

But when the whales they hunted became scarce,

the megalodon was unable to find enough food to sustain its huge appetite...

..and this colossal predator disappeared from our oceans.

Today, it's the great white that faces an uncertain future.

Their size has made them a target for trophy fishing,

which has left them vulnerable to extinction.

We think of giant animals as being invincible.

But as the megalodon and the great white both show,

the biggest beasts can also be the most fragile.

.

.

I'm on a journey across Africa

to search for the biggest beasts...

..and reveal the challenges faced by our megafauna today.

From the coast I'm heading north

into one of the continent's vast deserts.

A remote Martian landscape called the Namib Desert.

This is one of the driest locations in Africa.

Some years, not a single drop of rain will fall,

so understandably there's barely any vegetation.

This is not the type of place you'd expect to find a huge herbivore,

and yet it's home to a very special desert-dwelling giant.

Standing six metres from hoof to head,

and weighing over a tonne...

..this is the Angolan giraffe.

These are the only giraffe that live in the desert.

To survive, they need to eat several hundred kilos of leaves

every week.

So what's a megaherbivore doing in such a lifeless landscape?

I'm heading deep into the interior

to meet up with a team of conservationists

studying these giraffes.

That is a sight to behold.

Seeing such a massive animal in such a sparse landscape

is really quite mind-blowing.

I really do think that giraffes are one of the marvels

of the natural world.

But the thing that giraffes are renowned for

are their long necks.

On a fully grown adult,

it can reach up to three metres long.

That heavy neck weighs over 100kg.

But it's also the key to their survival.

Dried-up riverbeds are scattered with trees...

..fed by water deep underground.

Browsing at the top of the canopy

allows giraffes to reach the freshest leaves and shoots.

Incredibly, they get all the moisture they need from the leaves they eat.

So they can survive months without drinking a single drop of water.

(CRUNCHING)

But males have another use for those necks.

Females live in small nomadic groups.

And males must compete for their attention.

Rivals go head to head...

..in a duel known as necking.

It's a raw test of strength.

If neither backs down, they use their short antlers, or ossicones,

to deliver a decisive blow.

Only the winner earns the right to breed.

Surprisingly, despite these arid, conditions,

this population of desert-dwelling giraffes

is increasing in number.

To understand why they're doing so well,

scientist Emma Hart, from the University of Dublin,

is studying the genetics of this population.

Hi, Emma. How's it going?

Good, thanks. Nice to meet you. You too.

What are we doing out here? You've got a gun.

We're not going to be using them on the giraffes?We are, but it doesn't shoot bullets.

It just shoots the specially designed biopsy darts.

That dart is used to collect a tiny sample of genetic material

from the giraffe, without hurting the giraffe. It's non-invasive.

Great. Let's go and dart some giraffes!Let's go!

First, we need to creep close enough to get a clear shot.

We're doing our best to sneak up on one of these giraffes.

It's kind of futile, because they're the tallest animals in the world

and they can see us coming from a mile away.

It takes several hours.

But finally we get close enough.

Yep, you can stop there.

Taking photographs allows Emma to record which giraffe she's darted.

Like a human fingerprint, each has its own unique spot pattern.

OK, ready?

(FIRES DART)

You can see where his hooves were.

And here is our dart.

This contains DNA that is specific to that giraffe?

Exactly. So we already know who the individual is.

With this genetic information and that from all the rest of the giraffe in this area,

we'll be able to tell who he's bred with, who his offspring are

and how related he is to the various other groups of giraffe in the area.

Through her research, Emma is making some startling discoveries.

Males are travelling huge distances,

up to 1,000 kilometres a year

in search of food and females.

Giraffe need vast spaces to survive.

It's something they share with all our megafauna.

In other parts of Africa,

human activity continually chips away at their remaining habitat,

dividing it into smaller and smaller sections.

But this place is so remote,

these Angolan giraffes have all the space they need.

And that's why this desert

has become an unlikely stronghold for the tallest animal on the planet.

.

.

I'm on a journey across Africa

to encounter the biggest beasts

and discover the challenges they face.

From the desert, I'm heading to the continent's great grasslands,

home to more large grazing animals

than anywhere on earth.

And where there are big grazers,

there are also giant predators.

When it comes to big predators on the African plains,

the lion is often called the King of the Savannah.

And rightly so.

They are the largest hunter

and can tackle prey as big as a buffalo,

and when they work as a team, even elephants.

But their reign hasn't gone unchallenged.

There's another huge carnivore out here

with bone-crushing jaws twice as powerful as a lion.

Over thousands of years, these two giants have been locked in a battle for supremacy.

(WHINES)

The spotted hyena.

The lion's ultimate nemesis.

(GROWLS)

They live in huge clans ruled by a dominant female.

They're renowned scavengers...

..but also skilful hunters.

They can clock speeds of 60kph.

As social animals, hyenas share their spoils.

(LOW HOOTING)

Making a kill is one thing.

(WHINING)

But holding on to it...

is a far bigger challenge.

Lions are twice the size of hyenas.

They will kill any that get in their way.

(THE PACK HOOTS AND HOWLS)

(SQUEALING)

Lions steal 70% of all hyena kills.

So hyenas have evolved a simple strategy.

At night they come out in force.

(THUNDER CRASHES)

This time it's the lions that have made a kill.

There's no way a hyena can take them on alone.

(HOOTS)

Hyena calls can travel five kilometres across the open savannah.

(HOOTS)

Backup arrives.

(GROWLING)

(HOOTING AND SNARLING)

(SQUEALING)

One lion retreats.

(WHINING AND HOOTING)

(BARKING AND SNARLING)

Hyenas use a tactic called cooperative mobbing

to intimidate their rivals.

(GROWLS)

(HOOTING)

One by one, the lions back down.

(SCREECHING AND WHINING)

The last male stands his ground.

(COLLECTIVE SCREECHING)

But outnumbered 30 to one...

..even Africa's biggest predator...must concede defeat.

This battle rages day and night across the African savannah.

But the clash between giant predators

is nothing new.

(SNARLING)

Dinocrocuta, or the Terrible hyena,

was four times heavier than the hyenas of today.

Huge rounded skulls

gave an immense bite force.

Fossil evidence suggests they could take down ancient rhinoceros.

(SNARLS)

Its rival... A giant sabre-toothed cat.

Although lacking in jaw strength,

they had blade-like weapons.

(SNAPPING AND CRUNCHING)

For three million years,

these two goliaths went head to head.

But when a change in climate killed off their prey...

..both these megacarnivores disappeared.

(SNARLING)

Throughout evolutionary history,

big animals have always been prone to extinction.

(RUMBLE OF DISTANT THUNDER)

And today, in the jungles of Uganda,

one African giant illustrates just how vulnerable they can be.

The mountain gorilla.

Gorillas are the largest of the great apes.

Silverbacks weigh up to 200kg.

Their colossal size allows them to defend their family.

To sustain these huge bodies,

males must eat 18 kilos of vegetation every day.

But over the last few decades,

a pristine forest they rely on

has been relentlessly exploited.

30 years ago, there were just 600 left.

Now, thanks to huge environmental efforts,

that number is 900 and rising.

There's still a long way to go.

But the mountain gorilla has become a remarkable conservation success story.

.

.

On my journey across Africa,

I've seen the unique challenges facing big animals today.

But throughout evolutionary history,

this continent has been home to giants

whose size ultimately proved to be their downfall.

(BELLOWS)

Deinotherium was as tall as a double-decker bus.

A distant relative of today's elephants...

..it had a stubby trunk

and backward-pointing dusks.

It's thought these were used for stripping bark from trees.

But one million years ago,

when the climate changed...

..deinotheria couldn't adapt quickly enough...

..and became relics of a lost age.

(TRUMPETS)

Today, deinotherion's modern-day relative

has taken the title of the world's biggest, heaviest land mammal...

(TRUMPETS)

The African elephant.

The biggest males stand three metres tall...

..and weigh up to six tons.

But the most majestic adults...

..have one defining feature...

..immense tusks...

..that reach all the way to the ground.

The biggest perfect of the big,

these elephants are known as tuskers.

(BELLOWS)

These giants once roamed across Africa.

But today, due to poaching,

it's thought as few as 30 are left in the world.

To find out what can be done to save these few precious giants,

I'm heading to their last stronghold

in Kenya's Tsavo National Park.

It's only when you experience Africa from the air

that you can understand why this continent is home to giant animals like elephants.

This National Park alone covers 22,000 square kilometres.

There are no fences, no borders.

and animals are free to roam naturally

in search of food and mates

over vast distances.

I'm flying in to meet a conservation team

working to protect the last of the tuskers.

Joseph, how you doing? I'm good.Good to meet you.You too. I'm glad to be here.

The team is tracking these few individuals

to understand their annual movements

as they roam over an area the size of Wales.

Of all the giants I've searched for,

tuskers are undoubtedly the rarest.

It's not long before we locate a huge gathering of elephants.

This is brilliant. There's a line of elephants as far as the eye can see

and they're congregating here... About a hundred individuals.

This is really, really rare.

The reason they can do this is because it's rained here recently,

so there's lots of vegetation.

It's exceptionally green.

That means there's little competition for food.

(LOW GROWL)

Many of the adults have impressive tusks.

But there's no sign of a tusker.

For one simple, but tragic reason.

In the last ten years alone,

at least half the elephant population in East Africa

has been killed.

On the black market, the ivory from a tusker

could sell for half a million pounds.

So they have been systematically targeted...

..and almost wiped out.

For three days we scoured the landscape

without a single sighting.

But in our last few hours of filming...

..we finally catch sight of a giant.

(BELLOWS)

That is what I've been searching for.

That elephant is the biggest of the big.

That is definitely a tusker, and I can tell because those long tusks

reach all the way to the ground, even when it stood up.

That is so impressive!

(GRUNTS)

Together, those two tusks weigh more than me.

(GROWLS)

With this latest sighting,

ranger Joseph

takes photographic records

to identify this individual.

By recording the GPS coordinates of this secret location,

the team can build up a pattern of this elephant's movements.

What's the importance of gathering all of this data?

So you're taking all of this monitoring information,

then you pass it on the to the anti-poaching team,

and then they know exactly where to go.That's right.

Protecting tuskers like this one

has never been more important.

(GRUNTS)

Becoming a tusker is partly down to genetics...

..an inherited trait of growing longer and thicker tusks.

At 30 years of age, this male will now be starting to breed...

..and has the potential to pass on that big-tusk gene...

..to future generations.

But as elephants with the biggest tusks are poached,

that trait is rapidly being removed from the gene pool.

That ivory is so prized on the black market

that it's resulting in normal elephants having shorter tusks

or no tusks at all.

So that big-tusk gene is sadly being wiped out.

It's shocking to think that this is one of the last tuskers walking the planet today.

Elephants are just one of our giants fighting for survival.

Today, more than half of our planet's megafauna...

..is under threat.

(WISTFUL MUSIC)

My journey has shown there's one key thing

that all large animals need...

Space.

Today, those areas away from human habitation

are becoming increasingly hard to find.

Ultimately it's only by protecting the last of our planet's wild places

that we can protect the last of the giants.

subtitles by Deluxe E-mail sky.subtitles@sky.uk

.