All language subtitles for Secrets of our Living Planet 2of4 The Secret of the Savannah 720p HDTV x264 AAC MVGroup org_Subtitles01.ENG

Ten million species live on planet
Earth.

Each one is remarkable.

But none can survive on its own.

All life depends upon connections...

..unexpected, invariably complex,

beautiful relationships between
millions of plants and animals.

This time, in our grasslands,

I want to show you why these
antelope need these rhino...

..why this lone wolf...

needs an ant...

SNARLS

..and the incredible secret
that lies buried beneath them all.

Connections like these create
the planet's great ecosystems.

They're vital for all life.

I want to show you our world
as you've never seen it before.

Central Kenya...

..and this is whistling acacia
grassland.

The whistling actually
comes from the breeze

blowing across the holes
in these hollow galls...

..and they're home to one of
the grasslands' most intriguing
creatures.

This lizard is
the aptly named dwarf gecko,

and this one has laid a couple of
eggs

down here in this gall on the tree.

The perfect place for a nest,
you might think.

But this tiny lizard
can only safely lay its eggs here

thanks to one of Africa's largest,
most iconic and bizarre animals,

the giraffe.

The story of why the gecko
needs the giraffe is wonderful,

and it will take us on a journey
across the world,

to some of our most
breathtaking grasslands.

They are habitats which occupy
a quarter of the land surface
of our planet.

They support some
of our most spectacular wildlife...

and yet grasslands lack one of the
basic ingredients for life...

..a truly precious element.

It's this -

nitrogen,

a colourless, tasteless gas.

It's only when we chill it
down to 196 degrees below zero

that we can actually see it.

I can tell you

that almost everything that happens
out here in this grassland ecosystem

is governed by a craving
for this rare resource.

In fact, I'd go so far as to say
that grasslands can only function

because they can cope so ingeniously
with so little of it.

So, for once, perhaps this will make
the ecologist's job a little easier,

because to understand
how grasslands work,

all we need to do is
follow the nitrogen.

Australia.

The grasslands here have some of the
lowest levels of nitrogen on the
planet,

which makes the local wildlife
perfect for demonstrating
why it's so important.

Nitrogen is the magic ingredient.

When you add it to carbohydrate,
you get protein.

And protein is what you need
to make living tissue.

Protein is the building block
for life, all life.

A baby eastern grey kangaroo.

When he was born, he weighed
less than a one-pence piece.

His dad, on the other hand, is one
of the heaviest marsupials in the
world.

Which means that joey
has a lot of growing up to do.

In fact, from birth to adulthood,

he'll increase his body size
by 100,000 times.

And all of that
will be built with protein.

And you can't make protein
without nitrogen.

Right now, he gets most
of his protein from his mother,

and she gets all of her protein
from a diet of grass.

At the moment, these kangaroos are
just hanging out,

and they look like
a typical population of kangaroos,

but I can assure you they're not.

Because this is not
your typical Australian grassland.

It's Anglesea Golf Club
near Melbourne.

Kangaroos were here when the golf
course was built 60 years ago,

but since then,
their population has boomed.

At a recent count, there were 359
of them.

That's nearly 20 for each hole.

And the secret of their success is
down to these immaculate fairways.

This grass is so green and so lush
because it's had something added
to it.

This.

Nitrogen fertiliser.

And I know it's a product
of the industrial revolution

that's therefore led
to all of this lushness,

but it certainly proves a point -
the power of nitrogen
in a grassland.

It's added once a month.

It seeps into the soil,
is quickly taken up by the roots

and then converted into proteins
for stronger, healthier grass.

Great for golf
but perfect for the joey.

The extra protein means
that he can grow faster,

become healthier and live longer

and that's the power of nitrogen.

On the plains of East Africa,
there's an animal

that you might think
is the least likely to be affected

by nitrogen levels in the grassland.

SNARLING

Nitrogen, or indeed the lack of it,

plays a decisive role
in any grassland ecosystem.

It's even intrinsically entwined
with the ecology of large predators

like these lions.

GROWLING

This close, and I'm in no doubt

that these animals are
at the very top of their food chain.

But to find out
how nitrogen affects predators,

I need to start at the bottom
of the food chain...

..and it all begins
with a very special plant...

..one of the great unsung heroes
of our planet,

grass.

The really great thing about grass
is that it's simple.

Compared to other flowering plants,
shrubs and trees,

it requires minimal protein to build.

So it can take all of the nitrogen
from its roots

and put it not into bulky structures
but organise it efficiently,
yet simply,

to maximise photosynthesis
to produce its food.

So grass leaves have protein
at much lower concentrations.

But this gives grazing animals
a real problem.

Impala are one of Africa's commonest
antelope,

a favourite prey of big cats.

But their biggest challenge
is a much more basic one...

..how to survive
on nothing more than grass.

The key is being very fussy
about the sort of grass you eat,

because some grass is richer
in nitrogen than other grass.

This impala
is actually cherry-picking the leaves

with the highest concentration
of nitrogen.

Even so, she'll have to work hard
to extract it.

Just watch her neck closely.

Any moment now,
she's going to regurgitate

a ball of partially digested grass...

..and she'll process it all over
again.

It's called chewing the cud.

By digesting grass not once...

..but twice,

these animals can extract
as much of the nitrogen as possible,

but it still only works
on the very best grass.

Antelope, like these impala,

can only survive on a diet of grass
which is relatively high
in nitrogen -

grass like this.
We call it sweet grass.

This long grass, on the other hand,
is known as sour grass,

because the nitrogen in its leaves
occurs at even lower concentrations.

Antelope can't live here.

They simply can't get enough nitrogen
out of sour grass to survive.

But there is an animal here
that can change that...

..a very rare one.

This is what I've been looking for.

The animal that has deposited
this dung

processes grass through its gut
in a very different way
than antelope,

and I'm sure I can demonstrate that.

Here is some antelope poo,

and if I take just one of these
and break it open here,

you can see that what remains is
pretty much nothing more than dust.

Whereas this, on the other hand,
is very different.

If I break this one in half...

..the grass is still very visible.

RHINO SNORTS

The white rhino.

What an animal!

Their sheer scale...

I mean, they're the closest thing
perhaps that we have on the planet

to mammalian dinosaurs.

And of course, they have a reputation
for being pretty feisty,

so I'm being very careful
and not moving too quickly
and keeping my voice down.

In fact, this one's getting
a little bit close,

so I'm going to stop moving
and talk...talking altogether.

Their eyesight is poor, so if I'm
still, they may not notice me.

But they do have a great sense
of smell.

If the wind changes,
they could charge.

Absolutely fabulous things.

Now, one of these animals
has got no horns.

It hasn't lost them in a scrap.

They've been deliberately removed
by the park rangers here,

as these horns can have
a tremendous value.

Rhinos with horns
are prized by poachers.

The month before I arrived,
they killed one in this very park.

Cutting off her horn could save
her life,

and it's hoped that this practice
will save the entire species.

Losing a species like this

would have a drastic impact
on the entire grassland ecosystem.

Her huge size allows her to live
on grass where antelope just can't.

Her body houses a massive gut,
a fermentation chamber,

so she can make up
for the low quality of sour grass

by digesting vast quantities of it.

All of which means
she produces a lot of dung...

..which she drops
in a very specific place -

a midden.

For rhinos, this is important.
It's how they communicate.

Rhinos come here from far and wide.

By smelling the pile,
they can tell who's around,

how they're doing
and who is ready to mate.

It's a sort of faecal Facebook
but with added value.

It brings nitrogen-rich manure from
all over the grassland to one place.

So the grass growing here
becomes increasingly sweeter

until, as if by magic,
rhinos have created

a grazing lawn of sweet grass,

perfect for fussy eaters like impala.

Rhinos are ecosystem engineers
upon which many other animals depend.

That, surely, is their true value.

That's why they're worth
much more alive than dead.

Right across the world,

it's sweet grass that is crucial
for most grassland grazers...

..and it's this quest for sweet grass

that drives one of the largest
movements of animals on our planet.

Every year, one and a half million
wildebeest migrate 3,000 kilometres,

all because of nitrogen.

And this is when its impact
reaches the top of the food chain.

INSECTS BUZZING

BONES CRUNCHING

So, what has a lion kill
got to do with nitrogen?

Well, basically two things.

You see, the lions here
have identified

the richest source of nitrogen
available out here in the grassland -

large herbivores.

You see, their bodies
are made up of principally proteins,

and that protein
is where the nitrogen is.

Then it's the sweet grass which
dictates where lions like to hunt.

PURRS

King of beasts they may be, but
their lives are ruled by nitrogen.

But how would a grassland predator
survive

if there were no sweet grass
to hunt in?

Depending on where you are
in the world, the grassland always
has a special name.

In Africa, the savannah.

In the US, it's the prairies.

Here in South America,
it's the cerrado.

There's one animal that lives here
that I'd love to show you.

It's...it's really special.

I've never seen one in the wild,

but it's a truly fantastic animal
by anyone's standards.

This is Emas National Park.

The name comes from the Brazilian
for this bird...

..the rhea.

BIRDSONG

But it's not a rhea that I'm after.

What I'm after is a wolf.

Maned wolves are one of the largest
predators in South America,

but their home ranges,
their territories, are huge,

so they're not easy to find or see.

This wolf has a problem on her paws.

You see, these grasslands
are so low in nitrogen

that they can't support
herds of grazing animals,

like impala or wildebeest.

In fact, the wolf's survival here

is all thanks to a relationship

with one of the cerrado's smallest
inhabitants.

It's this, an ant.

And the story of why the wolf
needs the ant is an amazing one,

and it's all down to the way

that grassland ecosystems
survive against the odds.

Other species of canids -
dogs, wolves - hunt in packs,

but her life is a lonely one.

There's just not enough nitrogen here
for even two maned wolves,

so one of them has to go.

Hunting on her own means that
even the odd deer is off the menu.

Instead, she has to catch
more modest prey.

She may have walked miles
just for that mouse...

..and such meagre pickings
won't sustain a wolf.

So she has put herself
on a bizarre dietary supplement.

This is a lobeira fruit, from
the word "lobo", which means wolf,

and wolves love these things.

They make the perfect midnight snack.

Lobeira fruit make up
about half of her diet.

True, they don't have much nitrogen,

but they are packed with vitamins
and carbohydrates.

So eating fruit means
she needs to catch fewer mice.

SNIFFING

And that actually means
that she can survive

in this nitrogen-starved grassland.

But it gets even better.

The maned wolf is also helping
the fruit.

Wolves like to mark their territory,
and maned wolves are no exception,

and they like to choose
high spots to do so.

But, of course, here on the flat
cerrado,

such places are in short supply.

So, the one they turn to is this,

and this mound of soil here
is the nest of leaf-cutter ants.

When the wolf poos on the mound,
it has an immediate effect.

Soon most of the colony are out
in force.

The ants will salvage anything.

They'll even try what's left
of a mouse.

But one of them
has just found the real prize...

..a seed from the lobeira fruit.

The nutrient-rich coating from these
seeds will be fed to the ant larvae.

And, buried in the safety of the
nest, those seeds will germinate.

They've even got added fertiliser.

So what we have here is
an interaction

between three totally
disparate species -

the ant, the fruit and the wolf.

Now, the ants, they get food
delivered straight to their door.

The fruit has found something
to disperse its seeds

and something else to ensure
that they germinate perfectly.

And the wolves? Well, they're
effectively farming their own food.

What a story. What a story!

It's stories like that

that mean that you can always
entertain

a lifelong fascination
with nature.

And, you know, every single
leaf-cutter ant nest out here
on the cerrado

has a lobeira fruit tree
growing next to it.

It works.

And, you know,
the most exciting thing for me

is that none of the players
in this system,

the ant, the fruit or the wolf,

has any knowledge or regard
for what it's doing,

and yet it works perfectly.

Fantastic.

These connections are not just
important for the creatures
concerned.

Because of the way they move
precious nitrogen around,

they are crucial
for the entire grassland ecosystem.

Relationships between species
evolve over millennia,

but they can be destroyed
in just a matter of years.

And it's happened a lot
in Australia's grasslands.

This is Mount Rothwell
Research Centre in Victoria.

It's 400 hectares
of high-security grassland.

Scientists here are trying
to restore animal relationships

and thus mend a broken ecosystem.

It's surrounded
by 11 kilometres of fencing.

7,500 volts protect the perimeter...

..and it's patrolled every day.

I'm feeling a little imprisoned.

But then, this fence
is not designed to keep things in.

It's actually designed
to keep things out.

You see, in here

is the largest piece of native
Australian grassland left
in this region,

and this fence is helping keep out

a whole load of animals
that they don't want in here.

CAT MIAOWS

This moggy is, or was, someone's pet,

but she's also an alien predator
that didn't evolve in this ecosystem.

CAT MIAOWS

You see, Australia
has no native cats of any kind.

Down under, she's an unstoppable
killer

along with feral dogs and foxes.

These carnivores would do anything
to get their jaws and claws
on what's in here.

This is a brush-tailed rock wallaby.

And because of
these introduced predators,

he is now one of the rarest mammals
in the world,

and the extinction
of just a few key creatures like him

has had a catastrophic impact.

Crucial ecological relationships
are in tatters here,

and as a result,
this native grassland

is now far more endangered
than any tropical rainforest.

The question is, if you remove
all of the alien animals

and reintroduce the key native ones,

could Australia's grasslands
be brought back to life?

On the inside of this fence,

a relatively small community
of animals and plants has been saved,

and I've got to say,
some of them really are pretty odd,

and to stand any chance
of seeing them,

I'm going to have to wait
until after dark.

INSECTS DRONE

Welcome to the weird world
of the native Aussie night.

This is a southern brown bandicoot...

..and I'm getting a superb view of
it.

I'm so close that I can actually see
the saliva glistening in its mouth

as it's chewing its food.

It's one of about 20 different
species of bandicoot,

and they all come equipped with this
long, pointed and sensitive snout.

And they're principally insectivores,
meat eaters,

but they do play
a very important role

when it comes to maintaining
the plant community
in this ecosystem.

He spends all of his time
digging for food.

By the end of the night,
he'll have covered the grassland

with lots of snout-shaped
conical pits.

Here's one of the pits, here.

And when the wind blows,
grass seeds are caught in here

along with a lot of other detritus,
all of which is rich in nitrogen.

So they become a perfect place
for germination.

This is a bettong,
otherwise known as a rat kangaroo.

They're herbivores.

At the moment,
if you listen carefully,

you can hear it munching on some
roots or tubers that it's eating.

All of these animals are so tame

that's it's no wonder foreign cats
and foxes have almost wiped them out.

As it feeds, it effectively ploughs
this hard soil,

allowing air and water in,

vital for the plants that live here.

But so that the herbivores
don't do too much damage,

this miniature Serengeti
also has its own mini lion.

SNIFFING

This is an eastern quoll...

..a pocket-sized marsupial predator.

Don't be fooled by his size.

He can take prey
much larger than himself.

What's important is that
unlike cats and foxes,

quolls have co-evolved
with their prey

so they are a critical part
of this ecosystem.

The Rothwell experiment is working.

Rare species of plants, birds
and mammals, the entire grassland,

is making a comeback here.

The secret to healthy grasslands
is having the right species
in the right place...

..and there's one animal that
benefits grasslands more than any
other on Earth.

These monoliths dominate
the cerrado in South America.

There can be as many as 40,000
in one square kilometre.

From the outside, these things appear
entirely lifeless.

In fact, you could sit down here
alongside one and see nothing move
all day.

But living on the inside

is perhaps the most important animal
in this entire ecosystem.

They are grasslands' secret weapon
in the battle for nitrogen.

Termites, half-blind
distant cousins of cockroaches.

There are so many millions
living in this grassland

that their combined weight
is far greater

than that of all of the mammals
living here put together.

And yet you would have no idea
they were even here

if they didn't build
these huge mounds.

They build them as cooling towers,

to keep the temperature
of the colony on the inside

at an optimum 30 degrees centigrade,

and they are remarkably efficient,

normally accurate
plus or minus a single degree.

Not bad for a colony
of primitive insects.

But then, building these mounds
all over the landscape

is the least
of their accomplishments.

CAWING

Because, one way or another,

termites are fundamentally important
to almost all life here.

Especially the strangest of all,
the giant anteater.

These animals are related
to armadillos and sloths.

They're part of a group called
edentates, which basically means
"without teeth".

But whilst armadillos and sloths
do have rudimentary teeth,

if you were to perform a dental
examination on one of these guys,

which would be difficult
because their mouth is so small,

you'd find no teeth at all.

But it's not teeth he needs
to unlock the termites' secret.

If you look at its front feet,

you can see it's got these two huge
claws on each one of them,

and they can break into
just about any substrate.

It also uses them for defence.

It's said that if it's attacked
by a larger predator,

it will stand back on its tail
and lash out with those claws.

He uses his tongue,
which is over 50cm long,

flicking it in and out
at around 150 times a minute.

Giant anteaters
eat 35,000 termites a day.

Nevertheless,
you could be forgiven for thinking

that no matter how many
they hoover up, or how quickly,

they could never sustain
an animal this size.

But they do.

By weight, termites are the most
protein-rich food that you can find.

There's more protein
in these little insects

than there is in beans, nuts,
cheese, chicken, even roast beef.

And what's interesting is that
termites occur in ecosystems
all over the world,

and wherever they do,
there are creatures like this

that have evolved to feed
exclusively on termites.

The reason
termites are so rich in protein

is all down to some
very intimate relationships.

The first is with a fungus.

Deep within the mound,

the fungus breaks down dead grass
so the termites can digest it.

Not much else could eke
a living out of this stuff.

The second is more remarkable still.

You see, termites can obtain nitrogen

directly from the air.

And they achieve this through
another symbiotic relationship,

an even more intimate one.

Because living inside
their digestive systems

are amazing nitrogen-trapping
bacteria,

and it's this that gives termites
their special powers.

So using the nitrogen
they get from that bacteria,

the nutrients they get
from the fungus,

they're able to turn

this dead, woody material
into a productive food source.

This stuff, which is so low
in nitrogen, so low in protein,

they can turn into edible protein,

and that's how they can form
these vast colonies.

The termite mound
becomes a nitrogen hot spot.

That's good for anteaters

but also for all the surrounding
plants and for all the other animals
living here.

The incredible actions of termites
nurture grasslands
all over the world...

..including Kenya's
whistling acacia savannah.

Here, the impact of termites
goes right to the top...

..all the way
to the world's tallest land animal.

When I was a child, we thought
there was just one type of giraffe,

but now we know
there are six different species.

This one's a reticulated giraffe.

He can reach anything,

but of all the plants here,
he's chosen to eat
the whistling acacia tree.

But just look at it.

It's one of the best-defended plants
in the whole of Africa.

But why are these trees so well armed

against browsing animals
like these giraffes?

Well, the answer, you won't be
surprised, comes down to nitrogen.

You see, these trees' leaves
are absolutely packed with nitrogen.

That's why they are the botanical
equivalent of Fort Knox.

At the base of many of these acacias
are colonies of African termites.

The acacias' roots
are boring under the mounds,

tapping into a rich well of nitrogen.

As a result, these acacias become
an oasis in a nitrogen desert.

So it's really no wonder

that the thorns alone
don't deter giraffes from tucking in.

So, not to be beaten, the tree
employs another line of defence,

its own private army.

Now, just watch this.

I'm going to pretend to be a giraffe
browsing on this branch here.

So I'm going to pull at the leaves,
shake it about a bit,

try and not get jabbed
by the thorns here.

But just look at this.

Very quickly,

a whole mass of these Crematogaster
ants swarms out and covers my hand.

And I can tell you that, if you were
a giraffe browsing on this,

you wouldn't want these things
all over your tongue.

Each ant is armed
with a chemical weapon.

It's capable of squirting venom.

Each gall houses
a separate colony of ants,

and each branch might have
a dozen or more of these galls.

So the only way a giraffe
can get an ant-free meal

is to grab a quick snack
and then move on.

The tree has evolved
to produce these hollow thorns,

and they are the perfect structures
for the ants to make their colonies
inside.

And in return for the plant's
investment,

it gets these insects
as vigorous defenders.

But this is just the beginning of a
truly amazing web of relationships.

These are patas monkeys.

As grassland specialists,
they're the fastest-running primates
in the world.

In the 100-metre sprint, they'd beat
any Olympian by three seconds.

To fuel their energetic lifestyles,

their favourite food is Crematogaster
ants and their larvae.

The trick is finding them
in just the right position.

He could easily have his eye out
on those thorns.

Once ripped open,
the ants abandon the gall,

but this act of primate vandalism
only serves to enrich
this mini ecosystem.

You see, a short while later,
a new occupant has moved in.

Here, protected from predators
and the harsh sun,

a dwarf gecko has laid two eggs.

Because she isn't a threat to either
them or the acacia, the ants mostly
ignore her.

After four months, a perfect
miniature gecko hatches out.

It's completely defenceless,

but luckily, it's found itself
in the perfect nest.

It couldn't possibly appreciate
all of the creatures here
on the grassland

that have come together
to put a safe roof over its head.

The giraffe eats the acacia tree,

so it continually produces those
galls which form the geckos' home.

The acacia tree needs the ants
to protect its leaves and keep it
healthy,

and in turn, the patas monkey needs
those ants and their larvae as food.

And all of this can only happen

because the tree
has managed to accumulate nitrogen

from a grassland that's evolved
to prosper

despite the fact that this element
is always in short supply.

It's often said that you can only
tell who your real friends are in
times of need.

This is also true in nature.

You might ask if it really matters
if an animal becomes extinct.

Well, so intricate are
the connections in the natural world

that there's no way to predict the
impact of adding or removing species

until it's too late.

Who would have thought that a bettong
would need a bandicoot,

that a leaf-cutter ant
would need a maned wolf,

or, indeed, that a gecko
would need a giraffe?

Now, the complex web
of relationships that we've seen

have evolved over millions of years,

but we've only scratched the surface
of a myriad of stories

that, when they come together,
make these grasslands functional
ecosystems,

and it's here that I've learned
to see the real beauty in nature.

You see, for me,
it's not in the minute detail.

It's in the bigger picture.

Because this works perfectly,
and that is beautiful.

If you'd like to know more about
the fascinating web of links
between species,

the Open University has produced
some material both to inform
and inspire you.

For your free copy,

or to find out more about
Open University programmes, ring:

Or go to the website:

And then follow the links
to Open University.

And join me next time,

when I'll be travelling to the
world's greatest seasonal forest.