All language subtitles for The Living Planet s01e10 Worlds Apart.eng

Blue water covers most of our planet,
but in it are set tiny specks of land,

some the tips of volcanoes,
some mere rings of coral.

They're miniature enclosed worlds

where animals and plants become transformed
into new species with extraordinary speed.

If you wanted to pick a really remote desert islan
cut off from the rest of the world,

you might well choose this one.

This is Aldabra in the Indian Ocean.

The nearest land in that direction
is the coast of Africa, about 250 miles away.

Over there, about the same distance,
is Madagascar,

and if you sailed in that direction,
you wouldn't hit much

until you got to the coast of Australia
4,000 miles away.

The island is the tip
of an extinct submarine volcano

that rises 15,000 feet from the bottom of the
Indian Ocean and is capped with coral rock.

When it finally rose above the surface of the sea
about 50,000 years ago, it was lifeless,

but now, a mere 50,000 years later,
well, just look.

Frigate birds, thousands of them,
circle above one end of the island.

They've come from all over the Indian Ocean,
even from India itself 2,000 miles away,

to nest on this particular island
in the mangroves.

The white-headed birds among them
are immatures,

and there are two different species of them,
one bigger than the other.

The males inflate their scarlet throat pouches
to show that the site is taken,

and to attract the female.

When she arrives, he persuades her to stay
with ecstatic shakes of his head.

Red-footed boobies are here, too.

They're great travellers,
and their chicks, which are already fledging,

may well be fishing 3,000 or 4,000 miles away
within a year.

Noddies nest not on Aldabra
but on a neighbouring atoll,

building platforms of seaweed
in the Pisonia trees,

and beneath, on the open coral sand,
two million sooty terns lay their eggs.

Their vast numbers are an indication
of the richness of the surrounding sea.

Every day, the birds take from it
many tons of small fish,

little squid and other marine creatures.

The atoll itself provides no food for them.

All a pair of sooty terns seek from it

are a few square inches of dry land
on which to place their single egg,

and an absence of cats, rats
and all other egg-stealers and chick-eaters

that plague nesting sites on the mainland.

Such security is important to these terns,

for not only do they lay their eggs exposed
and unprotected on the ground,

but their young remain flightless
for several weeks after hatching

and a hungry cat could cause havoc among them.

So terns find it well worthwhile,
for the sake of such security,

to fly hundreds of miles to this island.

The plants that grow on remote islands
like Aldabra... how do they get here?

Well, some certainly come by sea.

In a short walk along this high-water mark,

I've picked up already
three different kinds of seeds.

Here's the biggest floating seed of them all.
This is a coconut.

There's the familiar nut
which contains the white flesh,

and this husk, from which we sometimes
make coconut mats, is the flotation device.

Nuts like this can float in the sea
for up to four months. This one is dead...

...but here is one that's alive and still sprouting

The green stem springing from the top,
a white rootlet striking down underneath.

Under natural conditions, coconuts
establish themselves at the head of the beach.

As they grow taller, they lean out over the sand
so that when they're full-grown,

their nuts will drop within reach of the high tide

and be washed out to sea
to spread to other islands.

A land-living animal also reached here by sea.

The time and place to find it
is at night among the coconut groves.

It travelled here as a larva in the same way
as the coconuts, floating in the surface waters.

One or two in a million
were washed up on the beach

and crawled ashore to live on land
among the coconuts, feeding on them.

It's almost the only creature here
likely to give you a painful bite,

so it needs tackling with care.

It's the coconut crab.

Its legs are so long that it can
embrace the trunk of a coconut palm,

and it has no difficulty
in clambering up to the top.

There it cuts down young nuts with its pincers,

and returns to the ground
to feed on the soft white coconut flesh.

Crabs as a group are sea-living creatures
and breathe in water by means of gills.

To breathe in air, the coconut crab
has developed large pouches within its shell

that have moist linings
and can act as simple lungs.

But when it breeds,
it has to return to the sea.

There it releases its eggs and sperm
into the water at high tide,

so that its larvae will circulate through the sea,

and may be washed up on some new island.

One exceptional land animal
made the voyage to Aldabra as an adult:

Its most famous inhabitant, the giant tortoise.

Most tortoises are naturally buoyant.

If one on the coast of mainland Africa, grazing
among the mangroves, were swept out to sea,

it might survive long enough to be carried
by currents to the islands of the Indian Ocean,

and later to spread among them.

That, almost certainly, is how ancestors
of the Aldabran giant tortoise reached here.

It's not a very hospitable place
for animals like tortoises

that feed on land-living plants.

The coral rock
which forms the substance of the island

erodes into a honeycomb
of wickedly sharp blades and spikes.

Any creature moving over it has to step with care
if it's not to cut itself badly.

Here and there, the rock forms deep pits
into which tortoises sometimes tumble.

When that happens, there is no escape,

and the trapped animals,
even if they survive the fall, die from starvation

Quite apart from such traps, the island
is a harsh, taxing place in which to live.

The tropical sun, beating down on the animals,
threatens to bake them alive inside their shells,

and the remains of casualties are common.

So as the day heats up,

the tortoises head determinedly
for the few trees that can provide shade.

Here and there on some beaches
grow low, windswept Guettarda trees.

By noon, the ground beneath their branches
is packed with refugees from the sun,

waiting for the temperature to fall
so that they can search for edible leaves.

Birds, too, can overheat.

The frigates swoop over the one almost
permanent lagoon of rainwater on the island,

snatching sips from its surface.

Tortoises, too, must have fresh water.

Although they don't drink every day,

they must do every week or so
if they're to survive.

Water can also cool an overheated body.

As the dry season progresses,

the water evaporates and the pools
get smaller and more crowded.

Many that came here for relief
are near the end of their strength.

Some are unable to drag themselves
out of the mud, and so die of starvation.

And yet, in spite of all these hardships,
the tortoises breed and proliferate.

There are some 150,000 of them on the atoll.

Their staple food is vegetation and
they crop the grass right down to the rootstock.

But as island animals everywhere tend to do,

they've broadened their taste in food
to include almost anything that is edible,

including the carcasses
of their dead companions.

Flesh is too nutritious
to be allowed to rot and go to waste

in this land where there is so little to eat.

50,000 years, which is the time, apparently,
that Aldabra has been above the sea,

is not a very long time in terms of evolution.

Nonetheless, 50,000 years of isolation
on the island

has brought changes
to many plants and animals that live here.

They've begun to take on their own character,

so now they differ slightly both
from the ancestors which colonised the island

and from their nearest relations
elsewhere in the world.

For example, this close-cropped withered turf
around me

contains about 20 different species of plants.

All have been relentlessly cropped
by giant tortoises like that.

And look, for example, at this little sedge.

Most sedges bear their flowers at the top
of stems that rise quite high above the leaves.

Flowers sticking up like this would not survive
long on Aldabra. The tortoises would eat them.

These Aldabran sedges bear their flowers
and develop their seeds

close to the rootstock where the jaws
of the hungry tortoises can't reach them.

The changes that take place in an island species
are not always directly useful like that.

Another of Aldabra's plants has changed in a way

that seems to have
no practical significance at all.

This is a lily called Lomatophyllum.

It's slightly different in colour from Lomatophyll
growing elsewhere, but that's all.

The difference is very trivial.

But some island plants are spectacularly
different from their nearest relatives.

Very, very rarely,
extraordinary double nuts like this

are washed up on the shores
of the coral islands of the Indian Ocean.

For centuries,
nobody knew where they came from.

Some said they were produced
by fantastic palm trees

that grew under the surface of the sea,
so they were called coco-de-mer.

People believed that their kernels
could be made into irresistible love potions

and that their shells, when turned into a cup,

would render the most powerful poison harmless.

A single nut like this
was literally worth a king's ransom.

It wasn't until the 18th century

that people discovered
that the palms that produced these nuts

grew in one tiny group of islands
in the Seychelles, some 700 miles from Aldabra.

The largest surviving group of these trees
stands on the little island of Praslin.

There are male and female trees.

The males produce small yellow flowers
on long spikes,

and on them lives a little gecko,
feeding on their nectar and pollen.

Once again, it's an island original,

slightly different in colour
from others in neighbouring islands.

The female flowers start as small reddish buds,
no bigger than a man's fist,

but they will develop into the biggest seed
produced by any plant.

It takes seven years for the nuts to develop,

and when they are mature,
they are so large and so heavy

that almost the only way of opening them
is with a saw.

Inside, you can see how very different
they are from coconuts.

Not only do they have two lobes to them,

but the nut itself is full solid with flesh.

Flesh that is so heavy
that these mature nuts won't float in sea water.

Indeed, sea water kills them.

And that means two things.

First of all, that these palms have never
been able to spread to other islands,

and secondly,
that they must have actually evolved here.

Isolation changes not only plants but animals.

On Aldabra, wandering among the tortoises
are sacred ibis with light blue eyes.

Others elsewhere have dark eyes.

The Aldabran ibis breed among themselves
and feed on small shore creatures.

Land crabs are far too big to be eaten,

but they have to be pecked
to clear them out of the way.

Several species of Aldabran birds have developed
slight variations that make them unique.

The kestrel here is slightly smaller than the
Madagascar species, but otherwise the same.

The Aldabran sunbird, however,
is a little darker than its African relations.

But perhaps the most dramatic
and certainly the most endearing quality

brought to some of the birds of Aldabra
by isolation is this.

Not only extreme tameness, but flightlessness.

This is the Aldabran rail.

Flying takes a lot of energy.

It's of obvious value
when escaping ground-living enemies,

but there are no such enemies
on Aldabra or other remote islands.

So some birds that reach such islands by air
have given up flying.

Their wing muscles have dwindled
and they can't fly even if they wanted to.

The Aldabran rail is only one example.

A kind of pigeon once lived on another island
in the Indian Ocean: Mauritius.

It, too, became flightless
and grew as big as a turkey.

It was so tame that European sailors
were able to kill it with clubs.

They called it the dodo,
and in less than 200 years after finding it,

they'd exterminated it.

Grazing alongside the dodo in Mauritius,

and living in other islands in the Indian Ocean
as well, were giant tortoises.

They, too, were taken for food by seamen
and were exterminated.

But Aldabra is so remote
that few ships come near it,

and here alone, the tortoises have survived.

It seems likely that the African ancestors
of these creatures were of a normal size,

and that these tortoises became giants
as a consequence of living on islands.

Isolation may have had another effect
on the tortoises as well.

When African tortoises are threatened,

they behave in the same way
as this baby Aldabran tortoise.

They first pull in their head,

and then they pull after it
their heavily armoured front legs

so that nothing sticks out and they're
comparatively safe from their enemies.

But when the Aldabran tortoise grows up,
its proportions change,

as this one's have done.

This one is now so big
that these huge legs won't fit into this space,

so that whatever it does, something sticks out.

It's a fair bet
that if there was a hyena on the island,

it would make a meal of the giant tortoise.

But there isn't on Aldabra, so this creature's saf

Just why the island tortoises
should have grown so huge,

and another species has done the same
in the Galapagos islands,

is by no means clear.

It may be that a large animal
with big reserves of fat

is better able to survive bad seasons
when there's little to eat.

It may even be
that with no predators on the island,

these long-lived creatures just go on growing,

but it is not a phenomenon
that is restricted to tortoises.

On an island 3,000 miles away from Aldabra,
there is another giant reptile.

Komodo is a small island in Indonesia.

From here, back in the 1920s,

came stories of a huge lizard
that became known as the Komodo dragon,

and here the dragons still live.

It's not difficult to find them.

All you need is the carcass of a goat,
preferably decayed and smelly,

and the scent will attract them from miles around.

It used to be thought that
these very big ones were entirely scavengers,

relying on what carrion they could find,

but now we know that
actually they are active killers.

They attack and kill goats,
young buffalo, and even on occasion, man.

The reason that I can stand here
with relative safety

is that their eyesight is not very good,
they are almost deaf,

and they rely on their senses,

primarily on that big yellow tongue
which flicks out and tastes the air.

So with any luck, the smell of these dead goats
is more powerful than mine,

so they will take no notice of me.

They are, in fact, the kings of their island.
They are the top predator.

There is nothing here
which preys upon them and is bigger,

and nothing with which
they have to share their food.

So, from that point of view,
there is no reason why they shouldn't grow big.

And the fact is that there is
a positive advantage in growing big,

because the big ones
are getting the bigger share of the food.

Not only that, but we now know
that these big ones eat small ones.

That perhaps is a reason why,
in the isolation of their island,

these kings of Komodo have grown so huge.

And they are indeed immense.

They're related to the water monitors
of Asia and Africa and the goannas of Australia,

but they are much more massive,

for whereas two-thirds of the length of these
other monitors is taken up by a long thin tail,

the dragon's tail is only about half its length.

Big ones like this can weigh up to 100 pounds
and grow to over nine feet long.

Komodo is not, like Aldabra,

a coral atoll growing
on the drowned tip of a submarine volcano,

but the eroded remains of one that stood
many thousands of feet above sea level.

Volcanoes, indeed,
have built many of the most isolated islands.

The Hawaiian islands,
lying in the eastern Pacific, are all volcanic,

and the biggest and newest of them
is still erupting.

Torrents of basaltic lava erupting from vents
10,000 feet up on the mountain

sometimes flow for many miles
down the volcano's flanks.

When, eventually, they cool and solidify,

they become vast slopes of black naked rock.

Such areas as this
may remain virtually sterile for decades.

Some vents produce vast quantities of granular
ash which builds up around them into cones.

Plants have a better chance
of getting root on such material,

and within a century or so,
the ash slopes may be covered with green.

These high islands
collect moisture-laden clouds,

and on the windward side,
rain falls very heavily indeed.

Streams flowing down the mountainside

cut through the layers
of loosely compacted ash, eroding deep valleys.

So, unlike a coral atoll,

which is a plain platform
of coral, sand and rock only a few feet high,

these immense volcanic islands of Hawaii

offered their colonists a great variety of habitat

from high cold slopes of ash on the summits

to well-watered valleys, hot, lush and humid,
near sea level,

from new, naked basalt to long-established
forest growing on ancient lava flows.

To exploit them, the animal colonists changed
not into just one new form, but into a multitude.

This bird, the palila,

is one of a large family of closely related
Hawaiian birds, the honeycreepers.

Their ancestors were probably
finch-like birds that were swept here,

perhaps by a freak storm
many thousands of years ago.

Once here,
they developed into over 30 different species,

each with its own diet and habitat.

The palila lives largely on seeds

and has the short, powerful beak
needed to open and crack them.

The 'amakihi, while there's no doubt
that it and the palila are related,

has a slender beak,
suited to picking up small insects

and sipping nectar from shallow flowers.

Some species have developed
striking feather colours and adornments.

These enable the male and female
to identify one another

so they don't interbreed with near cousins,

and the species becomes increasingly distinct.

So the 'apapane not only has a longer beak
to suit its almost exclusive diet of nectar,

but a conspicuous red head.

The 'akohekohe
lives on a mixed diet of insects and nectar,

and has developed a little crest of white feathers
at the base of its beak.

The 'i'iwi is scarlet
and has a particularly long curved bill

that allows it to probe deep
into trumpet-shaped flowers

such as giant lobelias and bananas.

And perhaps most engaging of all,
the akiapolaau,

with a splendid dual-purpose beak,

the lower mandible pick-like
to chip away bark to find insects,

and an upper mandible elongated into a probe
with which to winkle them out.

It's located a beetle larva
burrowing away within the bark.

Look how dexterously it uses the two halves
of its beak for these different purposes.

The situation amongst Hawaii's insects
is even more extreme than it is among its birds.

There is a kind of fly called Drosophila.
It's found in many parts of the world.

In North America, for example,
there are about 200 species,

but in these tiny islands of Hawaii,
there are at least 800.

It seems that soon after the islands' formation,

one or at most two species of Drosophila
reached the islands,

and they found the same situation as
the honeycreepers found, a lot of vacant niches.

And so they evolved to fill them,
and they are now Drosophila,

the larvae of which
feed on fruit or rotting leaves or fungi,

or bark or even spiders' eggs.

But now the situation becomes more complex
because in Hawaii, there are lava flows like this,

and such lava flows often isolate
patches of ancient forest like that over there,

and in one small patch of forest,

there may well be one particular species
of Drosophila that occurs nowhere else.

And there are some just there.

These particular ones belong to a group
which have evolved, in their isolation,

an extraordinary courtship behaviour,

just as some honeycreepers
have evolved bright colours.

It's an insect equivalent
of the arena display of antelope.

The males maintain tiny territories
and display and battle with one another.

Instead of antlers,
they've developed heads shaped like mallets.

In another species, the male courts the female
by hoisting his abdomen over his back

and showering her with an aphrodisiac perfume.

Isolation has also affected the wings
of Hawaiian insects.

Flying on an island is dangerous.

It risks being blown out to sea,

and this extraordinary bug
never takes to the air.

Its wings are tiny,
and used only for flirting in courtship.

This lacewing can't even use them for that.

Its wings have become fused together
to form a shell.

The Hawaiian cranefly
has lost its wings completely.

This cranefly's taste for fruit
is typical of its family,

but other insects
have changed their feeding habits.

This flightless bug has adopted
the hunting techniques of the mantis

which never naturally reached the island.

And this fly is going to get a shock.

The twig caterpillar doesn't,
like most twig caterpillars elsewhere,

feed on leaves, but has become a carnivore.

It detected the fly with tiny hairs on its back en

They trigger the caterpillar to arch backwards
and pounce on whatever touched it.

So isolation, by restricting the kinds of creature
that reached Hawaii,

allows those that did great freedom
to develop into different and unexpected forms.

Human beings, the Polynesians,
reached Hawaii several thousand years ago.

When Europeans arrived,
they found to their surprise

an unknown people
with an elaborate and splendid culture.

The Hawaiians were superb seamen.

They not only paddled dugout canoes,

but sailed immense ocean-going double canoes
that could carry several hundred passengers,

and that tradition survives still
in many parts of the Pacific.

The last of the really big canoes
must have disappeared about 100 years ago,

but still, in the remoter parts of the Pacific,

people remembered the techniques
that were used to sail them,

and still practise the skills needed to build them

This particular canoe,
which is very big for modern times,

was built on the tiny island of Ribono in Kiribati
the islands that used to be called the Gilberts.

It is only about 50 feet long, enormous for today,
but only half the size of the old canoes,

and still the people are prepared to sail
on journeys of up to 1,000 miles in it.

The techniques for building it
are those that were used for the old canoes.

The lashings, for instance.

They are made from the fibres of coconut husks.

Clumps are teased out, rolled and twisted

so that each fibre binds with its neighbours.

It is a repetitious job, but a skilled one
if the string is going to be strong,

and it is taken on
by the women and the old people.

Hundreds of yards will be needed
to build a big canoe.

It's used not only for lashing one spar to another

but for sewing together the planks
that form the sides of the big canoes.

The Pandanus tree produces strap-like leaves,
which, when dried and split,

provide ribbons that are woven
into strong and durable mats to serve as sails.

So if you have the necessary
knowledge and skill,

even a small atoll can provide
all the materials to build an ocean-going canoe.

In such craft, the Polynesians
travelled right across the Pacific.

For a long time, Europeans,
so proud of their navigating skills,

maintained that the Polynesian voyages
were accidental,

made when fishing canoes were blown off course.

But the huge canoes carried women and children,
and were loaded with plants and animals,

with every intention of founding new colonies.

The Polynesian navigators had and have
the most astonishing powers of observation

by which they find their way.

A particular kind of bird
during one season of the year

will always travel in a certain direction.

Some birds are ocean-goers, others
seldom travel far from their nesting grounds,

so spotting one
can indicate that there's land close by,

and following it may take you there.

Distant islands can be detected

by their effect on the ripples
on the surface of the sea.

Tall islands trail clouds of characteristic shape

like smoke from a chimney blown by the wind,

and since they are so high in the sky,

they can be recognised and identified
long before the island is visible.

Using such techniques and observing
the sun and stars, the pattern of the winds,

and feeling through the rudder
the movements of swells and currents,

the Polynesians colonised island after island.

Their original home was in the western Pacific.

They reached the Tahitian islands,
in the centre of the ocean, over 2,000 years ago.

They sailed so far eastward
that they reached Easter Island,

three-quarters of the way
to the coast of South America.

Those that settled here
seem to have been more isolated than most,

and, like so many other islanders,
they developed their own culture.

They carved the rocks
of their headlands into strange shapes.

On the flanks of the great volcano
that built their island,

they set up huge images whose enigmatic faces
have haunted the European imagination

ever since they were discovered
by westerners two centuries ago.

The heyday of the Easter Island culture

seems to have been passed
long before Europeans arrived,

for many statues were overturned
and some lay half-finished and abandoned

where they had been carved in the quarries.

The scale of these Polynesian voyages
is difficult to imagine.

From their headquarters in Samoa
to their most northerly colony in Hawaii,

which they reached by way of the Marquesas,
was some 5,000 miles.

The journey to Easter Island, about 3,300 miles.

But the most extraordinary voyage of all

took them across 4,000 miles of open ocean,
south to New Zealand.

The group that landed here,
ancestors of the Maori,

arrived about 1,500 years ago.

The land they discovered
must have been a great surprise to them,

for it was very different from the tropical island
from which they had come.

For much of the year, it was bitterly cold.

In the South Island stood great mountain ranges
covered with snow and ice

that the Maori can never have seen before.

Not only that, but the forests
were far richer in animals and plants

than any island they had yet discovered.

That was because these islands
had a very different origin and history.

They were neither flat coral atolls
nor were they the tips of volcanoes

that had risen above the surface of the Pacific
in comparatively recent geological time.

These islands of New Zealand
were ancient lands.

Fragments of a great supercontinent

of which Australia, Antarctica
and South America had been a part.

In consequence, they had on them
many more different kinds of animals

than other more recent islands.

They had animals like this.

This is the tuatara.

It's a reptile, it's nocturnal and solitary,
and it's a flesh-eater.

It feeds on insects, earthworms
and even young nestling birds.

It might look like a lizard,
but it's a more ancient creature than that,

more closely related to the early dinosaurs

than it is to the modern family of lizards.

Once creatures like it must have swarmed
over that great supercontinent,

but New Zealand split away
from the supercontinent

before the great expansion of the early mammals

which ultimately led to the extinction
of most of the early reptiles.

Only in New Zealand
did the tuatara remain safe.

And New Zealand also has been
a sanctuary for another early creature.

The kiwi. It's a bird, but what an odd one.

It has no visible wings and no tail
and lives in a burrow.

There, it produces a single and enormous egg.

Flightless, living in burrows,

with feathers so long and loose
they look like shaggy fur,

and running quietly across the forest floor
at night in search of food,

this odd animal could be considered
a kind of bird equivalent of a mammal.

Indeed, the kiwi does play that role
in these islands

where originally there were
no land mammals of any kind.

It has, however, retained that characteristic
possession of the bird, a beak...

...and it uses it to collect worms,

plunging it deep into the earth
to smell for them as a mammal does.

The ancestors of the kiwi were flightless
before New Zealand was isolated,

for the kiwi is a ratite.

Other members of that family
of ancient flightless birds

still survive on other fragments
of the great supercontinent.

There's the ostrich in Africa, the rhea
in South America and the emu in Australia.

All those are bigger than the kiwi,

but the kiwi once had a cousin
living here in New Zealand

that was bigger than the lot of them.

It was probably the tallest bird
that has ever existed, the moa.

Its bones have been found
in great numbers here in New Zealand.

Often in between the ribs
have been found piles of polished pebbles.

They were the stones from the gizzard
with which the moa ground up its food,

and from the vegetable remains, we know
that it ate fruit, twigs and the leaves of trees.

There were a dozen or so
different species of moa of varying sizes.

This particular one was the biggest of all.

It was not the heaviest bird
that has ever lived,

its relative, the extinct elephant bird
that lived in Madagascar was that,

but its weight nonetheless
was substantial, about 520 pounds,

and it was the tallest of all birds,
standing over 13 feet high.

In fact, it was the bird equivalent
of a giraffe.

This is the mummified head and neck
of one of the smaller species of moa,

and it suggests, because many necks
have been found attached to heads,

that the Maori had so much moa meat

that they could afford to throw away
sections like this.

The Maori not only reduced
the number of moa by hunting,

they also burnt down the forests
on which the moas depended.

And so, by the time the Europeans arrived here
in the 18th century,

the last of the moas
had been extinct for some 200 years.

But in the millions of years that have passed
since New Zealand was isolated as islands,

many more modern creatures have arrived here.

They've got here, as they've managed
to get to islands all over the world, by flying.

Some have changed only a little
since they arrived.

The kereru is still quite clearly a kind of pigeon

And this, the kea, is still recognisably a parrot.

Its ancestors came, doubtless,

from that great parrot homeland, Australia,
1,000 miles away.

Since it's been here,
it's probably changed its habits a good deal,

for it's taken up life in the cold, high mountains

where it feeds on berries and roots,
buds and insects.

It has also, with that adaptability of diet
characteristic of islanders,

become a general scavenger,

and will even feed on carrion
like a crow or small vulture.

One parrot, here, however,
has been changed extremely by island life.

The kakapo.

There are no ground-living
leaf-eating mammals on the island,

so this has become
a kind of parrot-equivalent of a rabbit.

It's extremely nervous, nocturnal,
and it lives on vegetation,

but it shows those two characteristics
of island-living creatures.

It has lost its powers of flight,

so its only defence
is to freeze motionless as it's doing now.

And secondly, it's a giant.

It's the biggest of all the parrots by weight.

A big one can weigh over three kilos.

It also shows only too vividly
a third characteristic of island-living forms:

Their extreme vulnerability.

When their islands are invaded by outsiders,
they often have no defence.

The kakapo's troubles started
when the Polynesians first came to New Zealand.

They brought a kind of rat
which may have preyed upon the nestling kakapo,

and the Polynesians themselves hunted it.

The real catastrophe came
when Europeans arrived,

because they brought with them
those two merciless killers, the stoat and the cat

Against them,
the kakapo had no defence whatever.

Very rapidly, its numbers diminished

until today there are
not more than 60 individual kakapo left.

To give them some chance of survival,

they've been taken to a small offshore island
that has been cleared of cats.

Elsewhere, these domestic pets
that were brought here to catch mice in houses

have run wild in the forests,
and prey on native birds

which have not acquired the right reflexes
to save themselves from its attacks.

Cats are not the only foreign killers here.

Ferrets were imported
for hunting introduced rabbits.

They are domesticated polecats.

Some escaped,
reverted to their wild state and bred.

This one is feeding on a penguin chick
which must have been an easy victim.

None of New Zealand's flightless birds
are safe from them.

People also introduced plant-eating animals.

Possums were brought from Australia as pets.

Rabbits were also imported
to provide meat and fur,

and to put to good use,
as the importers must have thought,

the abundant grass that was going to waste.

And red deer were released in the mountains
to provide hunters with sport.

Yet these seemingly harmless vegetarians
had a catastrophic effect on the native animals.

They grazed so effectively
that they destroyed the trees and bushes.

The soil was washed away
and the forest devastated.

Creatures were robbed of their cover
and vegetation.

The problems of halting this destruction
are very great.

This extraordinary bird is the takahe.

Like the kakapo,
it epitomises the effects of island-living.

It's become a giant,
for it's a rail, like the one in Aldabra,

and the biggest of its family.

It's unique to these islands, it's flightless,

and has virtually no defence against invaders.

At the beginning of this century,
it was thought to be extinct.

Then, after no one had seen a living takahe
for over 50 years,

a small population was discovered
in a remote valley in South Island.

There are about 200 left.

They are unlikely to spread,
for their habitat elsewhere has been destroyed,

and there is the greatest difficulty
in getting them to breed in captivity.

So, unless man is prepared to change his attitude
and become an active protector

as he has done here in New Zealand,

those strange specialised islanders

are doomed to the fate of the first
island-living creature that man exterminated

and become as dead as the dodo.

Of course, not all the creatures
that you find on islands

necessarily spend all their time there.

Some like those tough international
travellers over there, the gannets,

just come here for lodging.

They, like the frigates
and the boobies of Aldabra,

the noddies and the terns
of a thousand tropical atolls,

find their food, not on the islands where
they come to nest, but in the surrounding seas,

and that is the vast and complex community
that we'll be looking at next time.

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