Planet Earth (2006): Season 1, Episode 8 - Jungles - full transcript
On 3% of the Earth's surface, the rain forest is the habitat for half our animal species, even 80% of insects. So its wildlife is most competitive, like the birds of paradise's mating, and specialized with unique relationships of predation, parasitism etc. For plants, the quest for light is key to stratification, paralleled by interacting animals eating fruits, leaves and other animals. Even the jungle cacophony is stratified. On the soil, recycling specialist like fungi restart the cycle of life. In Central Africa even herds of elephants specialize in following self-made forest paths.
The coast - the frontier
between land and sea.
This is the most dynamic
of all the ocean habitats.
The challenge here is
to survive change.
Extreme change.
Cape Douglas, on the most
westerly of the Galapagos islands,
totally unprotected from the massive
rollers of the Pacific Ocean
and one of the roughest
coastlines in the world.
The marine iguanas of the Galapagos
are the world's only sea-going lizards.
Seaweed is all they eat,
but doing so is a dangerous business.
The local crabs have
become specially flattened,
minimising the effect
of the pounding waves.
And the iguanas have huge
claws to grip the rocks.
This seaweed really is fast food.
There are only a few seconds
in which to grab a few mouthfuls
before the next breaker
comes pounding in.
Female iguanas feed
only on the exposed rocks,
but the males which are larger swim and
dive beneath the surface to reach the weed.
They go as deep as ten metres,
for there beyond the destructive reach
of the waves, they find the best fronds.
Being cold-blooded they
have to return to land
after about ten minutes or
so to warm up again in the sun.
Finding food is not the only
challenge for coastal residents.
These rocky shores are hardly
a safe place to lay their eggs
and each year the marine iguanas
have to journey inland
to find a more suitable one.
The females lay their eggs in burrows
and leave them there to hatch,
and to do that they
need nice soft sand.
Down at the water edge, it was easy
to escape danger in rocky crevices,
but up here the females
are dangerously exposed.
A Galapagos hawk.
The lizards don't give up
without a struggle.
These hawks stay on the coast all year
But they are exceptional.
The majority of the birds
that frequent this frontier
spend most of their time elsewhere.
In or above the open ocean.
However all seabirds have to come
to land in order to lay their eggs.
And after spending many lonely
months searching the ocean for food,
they have to re-establish
their social relationships.
Frigate birds display and
exchange nesting material.
Waved albatross dance.
The need to lay their egg on firm ground
ties the albatross to the coast
but parental responsibilities
are shared.
While one looks after the egg,
...the other can go off to feed.
The need to breed brings
many different animals
to the coast each year
for a few weeks.
Male sea turtles spend all
their lives at sea, but the females,
like birds, must come to
land to lay their eggs.
To do that green turtles that live
and feed off the coast of Brazil
swim fifteen hundred miles to the
tiny island of Ascension
that lies bang in the middle
of the Atlantic Ocean.
Exactly how they manage to
navigate with such accuracy
and find this tiny lump of rock,
just seven miles wide is a mystery.
But each year up to five thousand
turtles manage to do so and then,
close to the coast of Ascension,
they mate.
Travelling to and from Ascension and
nesting here can take up to six months
and throughout that entire time,
none of them feed at all.
After mating a female has to
leave her natural element
and haul herself up onto land.
She does so at night,
laying about three or four times
at around fifteen day intervals.
After that she then swims all the way
back to the seas off Brazil.
She returns to this very same
island throughout her life.
Remarkably, all the world's sea turtles
return year after year
to just a few traditional
breeding sites.
Crab Island, in Australia,
is one of them.
This tiny two-mile long crescent of sand,
lying a few miles off
Queensland's northerly tip,
provides nesting sites
for half the entire population
of one of the world's
rarest sea turtles.
Flat-backed turtles are large,
over a metre long
but they have to be careful.
There are other giant
reptiles here too.
Salt-water crocodiles.
Every night throughout the year
there are flat-backs burying their eggs
all along this lonely stretch of sand.
Nine weeks later and things
are about to happen.
These eyes shining in the darkness
belong to night herons.
As if from nowhere, hundreds of birds
suddenly appear on the sand dunes.
Pelicans wait patiently.
Jabiru storks pace up and down.
Before long they see what
they've been waiting for.
Because these turtles lay
their eggs throughout the year,
the hatchlings emerge night after night
in a steady trickle of beak sized meals.
Pelican's broad beaks allow
them to dig out the hatchlings
before the herons can spear
them on the surface.
The surf may be hundreds of metres away
and at least a third of the tiny turtles
do not survive the journey.
And its not just the birds
that take them.
Crocodiles, sharks and hungry fish
are all waiting in the shallows.
In fact only one in every hundred
hatchlings will survive to adulthood.
Another beach, another continent,
and a very special night.
Here in Costa Rica there is a turtle which
has found a way of reducing these dangers.
When Ridley's turtles arrive
to lay their eggs
they don't come in tens or hundreds...
but in thousands.
Over the next six days around four hundred
thousand females will visit this beach.
At the peak time, five thousand
are coming and going each hour.
The beach gets so crowded that
they have to clamber over one another
to find a bare patch of sand
where they can dig a nest hole.
Forty million eggs are laid
in these few days.
So these turtles ensure
that six weeks later
when their hatchlings emerge
it's not just a trickle.
It's a flood.
On some nights, over two million
hatchlings race down to the sea together.
With so many appearing simultaneously,
the predators are overwhelmed and most
of the young turtles reach the sea safely.
Leaving the sea and emerging onto
land is hard enough for turtles.
It'd even harder for fish.
Each year for hundreds of miles
along the Newfoundland coast,
capelin throw themselves
onto the beaches.
At least a million tonnes of
fish floundering out of the water
a real gift for scavenging
eagles and gulls.
Odd though it may seem for a fish,
these capelin,
like the turtles, have also
come out of the sea to breed.
The males are trying to
fertilise the eggs
that the females are
depositing in the sand.
Like the Ridley's turtles,
they have synchronised their mass
laying with the tide.
In a few days it will be over.
Most of the capelin die but only after
they've left their eggs in the sand.
Other capelin populations
lay their eggs
in the ocean so why do the
Newfoundland fish spawn on land.
It seems that eggs deposited in
the beach may be safer
from predators and develop faster
than in colder waters out to sea.
But wherever they do so,
the huge spawning shoals
provide the concentration of food that
seabirds need when they assemble to breed.
Ninety five percent of the
world's seabirds nest together,
mostly in large spectacular colonies.
This is Funk Island forty miles
off the coast of Newfoundland
an isolated rock crammed
with breeding sea-birds.
This was the last breeding ground for the
flightless Great Auk, sadly now extinct.
Today it's still the world's
largest Guillemot colony.
Over a million of them share the
crowded island with 250,000 gannets.
It's not the lack of suitable sites
that causes the seabirds
to breed in such densities.
Here in the North Atlantic,
there's a wide choice of
empty coastline that
the birds could use.
The key factor limiting the size
and location of seabird colonies
seems to be the availability of food
in the surrounding ocean.
There are lots of hungry mouths to feed
and a constant demand for fish.
Throughout the long summer days
at colonies like funk,
There's a continual stream of birds,
heading out to the ocean to find food
and returning with full crops
to feed their young.
Gannets will travel up
to two hundred miles
from the colony on
a single foraging trip.
They are not fussy eaters
and will take everything
from tiny sand eels to herring.
Puffins, on the other hand,
are very particular about
what they eat and because they can
only fly short distances,
they only nest where there's a good
supply of suitable food close by.
One such place is the sea of Okhotsk
in far eastern Russia.
This is the island of Talan.
Throughout the long arctic winter,
it is encircled by ice.
But as spring approaches,
that begins to break up
and seabirds that have spent
the winter feeding out
on the open ocean far to
the south begin to return.
Its isolated position and steep cliffs
make Talan a perfect nesting site.
The Tufted Puffins arrive first.
These are the Pacific cousins of
our less spectacular Atlantic species.
Horned puffins soon follow.
In all, fourteen different species
return to Talan each spring
and in just a few weeks
the once silent cliffs
come alive to the calls of
4 million breeding seabirds.
This is a multi-storey avian city.
Assembling in these dense colonies after
having spent a largely solitary life
at sea provides the birds with
the social stimulation
that is the key to co-ordinating
their breeding.
By nesting and laying together
they ensure that
most of their chicks will leave
the nest at exactly the same time.
Just like the turtles this is the way
they spread the impact of predators.
The world's largest eagle.
Steller's sea eagle.
A third as big again as a golden.
Throughout the summer, the eagles
hunt in Talan's crowded colonies.
Riding on the updrafts,
they patrol the top of the cliffs,
looking out for any Kittiwake
that ventures too far from the rock face.
Suddenly the huge eagle stoops
with the aerial agility of a falcon.
Co-ordinated panic among the kittiwakes
confuses their attacker.
But the eagle doesn't give up.
And it has got one.
Another kind of seabird on Talan
has a particularly effective way
of defending itself against predators
but it doesn't appear until
an hour before sunset.
As if from nowhere, dense swarms of
seabirds suddenly arrive off-shore.
They're spent the day feeding far away,
where the sea ice has already broken up.
They are crested auklets,
hardly bigger than starlings.
A million of them return to Talan each
year to nest in its fields of boulders.
For an hour before sunset,
the hillsides comes alive
with huge flocks of circling auklets
They're nervous.
No one wants to be the first to land.
Auklets are very social when
they are back together at the coast.
One of the advantages of nesting
in such densities
may be the chance to share
information on good feeding sites.
It also gives them the
opportunity to court.
But perhaps most importantly,
there is safety in numbers.
Ravens and peregrines circle above
the scree slope every evening.
By taking off together,
the auklets hope to confuse the predators.
Eventually their persistence
pays off.
The birds that face the
greatest challenge in coming
to the coast to nest are
surely the penguins.
Unable to fly, they have no alternative
but to brave the immense waves.
Most penguins live in the southern ocean
and they have to accept being
hurled about by the surf.
Whatever the weather, the penguin parents
have to come back to feed their chicks.
A southern sea lion bull
he knows the penguins always use
the same traditional landing beach.
Having braved the thundering surf,
the penguins have to make a mad dash
across open rock to get to their nests.
Despite his massive size and
a body adapted for swimming,
the bull chases the penguins for forty
or fifty metres across the rocks.
Having caught his penguin, the sea lion
carries it out into deeper water where,
by violently thrashing the little body,
he skins his meal.
The seas around the Falklands are some
of the roughest in the world.
In spite of that, the southern ocean
is home to millions of tiny seabirds
hardly bigger than swallows-petrels.
Being so small they are very
vulnerable to the bad weather.
A severe storm can blow
them miles off course
and keep them away from
their nests for days.
But these birds have developed a very
effective solution to that problem.
They lay a rather special egg.
Most bird's eggs, left exposed for even
a few hours, will chill and never hatch.
But these eggs are different.
They can be left for several days
without incubation and remain undamaged...
...while the parents struggle
home through the storm.
Prions have also come up with
a good way to avoid most predators.
They never come back to the
coast until after dark.
These are Thin-billed Prions.
Their burrows honeycomb this
hillside in the Falklands.
It'd deserted throughout
the daylight hours...
...but as soon as it's dark
and difficult for airborne
predators to hunt...
...the prions return.
As soon as they land, they call.
The problem, of course...
...is finding your burrow
among all the others.
He's listening out for
his mate's call...
...and down he goes.
The Alaskan coast.
It's spring and the last of
the winter storms is subsiding.
The plankton in this sea is in
bloom again and just off shore,
humpback whales have
returned to feed.
For these huge animals, there is a real
risk in coming into such shallow water
and each year a good number
of them pay the price.
It is an ignominious ending
for an ageing whale.
But so much flesh will not go to waste.
A black bear emerges
cautiously from the woods.
Visitors to the coast that don't come to
breed, have usually come to scavenge.
A whole range of different animals
have learnt to exploit
the enormous quantity of food...
...that washes up everyday on
coastlines around the world.
But like so much at the coast
the quantity of flotsam
and jetsam is unpredictable.
Nobody can rely on it alone.
This carcass even attracted
a shy pack of wolves only too happy
to anoint themselves with the...
...scent of rotting whale.
It was months before the
scavengers finally
cleaned up all the meat
on this huge and...
...unpredictable gift from the sea.
Whales give birth to their young at sea
and so can spend their entire lives there.
Other marine mammals - one of that are
in fact distant cousins of bears
have to return... each year to
their ancestral home on land.
The high arctic
Here lives one of them... the walrus.
Walruses spend nearly
all their lives at sea,
but each year for just a few weeks...
...they have to return to the coast.
They seek out isolated beaches
like this one on Round Island in the...
...far northern Pacific.
Suitable sites like this,
free from bears, are so scarce...
...that at times as many as
fourteen thousand animals
will cram themselves on to this...
...one beach.
When they first emerge from
the sea the walrus are white.
That's because being warm-blooded
animals living in very cold ocean,
they conserve heat by...
...keeping their blood concentrated
in the core of their bodies.
On land it's warm enough for them
to allow their...
...outer blood vessels to dilate and
that turns their skin from white to pink.
Now they can moult the outer
layers of their skin,
rubbing themselves up
against the rocks.
But more than anything
else coming to land
brings the walrus relief
from having to spend energy
maintaining their body temperature
in an icy-cold ocean.
Heat conservation, in fact, may well
be the primary reason so many...
...sea mammals are forced to
return to the land each year.
The world's coldest seas
are in Antarctica.
Each spring, half the world's
Southern Elephant seals
return to the island
of South Georgia.
Elephant seals have particularly thick
insulation of blubber that keeps them warm.
For them breeding is the only
reason to leave the sea.
With temperatures down
to minus 20...
...and hundred mile an hour winds,
it can't be comfortable out on the beach,
but heat dissipates more
rapidly through water...
...than through air so even
in these conditions...
...their young which at first
don't have a thick coat
of blubber will be far
warmer on the land.
Once the males are established on the
beach the females soon follow.
Within just ten days the empty beach
fills up with six thousand elephant seals.
Almost immediately the females give
birth to pups sired the previous year.
Their milk is very rich and the pups
grow astonishingly quickly.
In just three weeks they turn form thin
bags of skin to fat balls of blubber.
As soon as they've given birth,
the females become sexually
receptive again...
...and it's now that the
advantages of breeding
in such dense colonies become clear.
Females can make their
choice from many males,
while successful males can
have access to lots of females.
But to gain that access and
control a harem of females,
the bull must be prepared to fight.
The larger the male, the louder the roar
and the more likely he is to win.
When males are well matched these bloody
battles will last twenty minutes or more.
Eventually, the loser retreats into
a stream already pink with his own blood.
These battles certainly help females
select the strongest bulls...
...but they bring great
dangers for the pups.
Each year, in the denser
parts of the colony,
a fifth of the pups are
crushed to death.
This is why it may
be better to mate
at the edge of the beach
close to the sea.
Less dominant males hide
in the surf.
They are waiting to try
and steal an illicit mating...
...with females as
they come and go.
This male knows he has been
spotted by the big bull
who claims all the females
on this part of the beach.
Breeding in groups can bring advantages
to pups as well as to adults.
Along the coast of Patagonia southern sea
lions breed together each year
in groups several hundred strong.
For the growing pups these colonies
act rather like a school.
The bonds and relationships
developed here on the beach
may be vital for the
rest of their lives.
Sea lions are very social animals
and as adults and young forage together,
they probably share...
...information about the location
of good feeding sites.
Conditions here could hardly be better
for the growing youngsters.
As the tide goes out it leaves behind
a selection of sheltered pools.
Perfect places for
learning to swim.
At high tide...
...it is easy for the pups to take their
first experimental dips in the surf.
A killer whale.
These young pups have never seen
anything like it before.
The Whales though are
very experienced.
Each year this same group turns
up along the coast
at precisely the same time
as the pups are starting to swim.
The whales need to surprise the pups,
so they have stopped calling
to one another and keep silent.
Speed is everything.
The whales do not take pups
that are out of the water,
but sometimes their momentum
drives them right up the beach
and then there's real danger
of getting stuck.
The whale has to thrash in this
frenzied way to get off the beach.
Most of the pups are taken into deep
water while they're still alive.
And there the whales - apparently.
Play with them.
Often an adult whale is joined
in the game by a youngster.
It may be learning how to grab a seal pup
before it risks a drive up the beach.
Whatever the reason the seal pup.
Still alive
is tossed back and forth
for over half an hour.
Even when the pup is dead, the whales'
sport is not completely over.
We can only speculate at the real reasons
behind this extraordinary behaviour.
But for the whales, the hunting
season is a short one.
Before long the pups learn to
stay well clear of the water
and the whales become less
and less successful.
After just two weeks, they move on.
The killing season is over.
That's how it often happens
along the coast.
Things are always changing.
They're never the same
for long in this,
the most dynamic of all
the ocean's habitats
between land and sea.
This is the most dynamic
of all the ocean habitats.
The challenge here is
to survive change.
Extreme change.
Cape Douglas, on the most
westerly of the Galapagos islands,
totally unprotected from the massive
rollers of the Pacific Ocean
and one of the roughest
coastlines in the world.
The marine iguanas of the Galapagos
are the world's only sea-going lizards.
Seaweed is all they eat,
but doing so is a dangerous business.
The local crabs have
become specially flattened,
minimising the effect
of the pounding waves.
And the iguanas have huge
claws to grip the rocks.
This seaweed really is fast food.
There are only a few seconds
in which to grab a few mouthfuls
before the next breaker
comes pounding in.
Female iguanas feed
only on the exposed rocks,
but the males which are larger swim and
dive beneath the surface to reach the weed.
They go as deep as ten metres,
for there beyond the destructive reach
of the waves, they find the best fronds.
Being cold-blooded they
have to return to land
after about ten minutes or
so to warm up again in the sun.
Finding food is not the only
challenge for coastal residents.
These rocky shores are hardly
a safe place to lay their eggs
and each year the marine iguanas
have to journey inland
to find a more suitable one.
The females lay their eggs in burrows
and leave them there to hatch,
and to do that they
need nice soft sand.
Down at the water edge, it was easy
to escape danger in rocky crevices,
but up here the females
are dangerously exposed.
A Galapagos hawk.
The lizards don't give up
without a struggle.
These hawks stay on the coast all year
But they are exceptional.
The majority of the birds
that frequent this frontier
spend most of their time elsewhere.
In or above the open ocean.
However all seabirds have to come
to land in order to lay their eggs.
And after spending many lonely
months searching the ocean for food,
they have to re-establish
their social relationships.
Frigate birds display and
exchange nesting material.
Waved albatross dance.
The need to lay their egg on firm ground
ties the albatross to the coast
but parental responsibilities
are shared.
While one looks after the egg,
...the other can go off to feed.
The need to breed brings
many different animals
to the coast each year
for a few weeks.
Male sea turtles spend all
their lives at sea, but the females,
like birds, must come to
land to lay their eggs.
To do that green turtles that live
and feed off the coast of Brazil
swim fifteen hundred miles to the
tiny island of Ascension
that lies bang in the middle
of the Atlantic Ocean.
Exactly how they manage to
navigate with such accuracy
and find this tiny lump of rock,
just seven miles wide is a mystery.
But each year up to five thousand
turtles manage to do so and then,
close to the coast of Ascension,
they mate.
Travelling to and from Ascension and
nesting here can take up to six months
and throughout that entire time,
none of them feed at all.
After mating a female has to
leave her natural element
and haul herself up onto land.
She does so at night,
laying about three or four times
at around fifteen day intervals.
After that she then swims all the way
back to the seas off Brazil.
She returns to this very same
island throughout her life.
Remarkably, all the world's sea turtles
return year after year
to just a few traditional
breeding sites.
Crab Island, in Australia,
is one of them.
This tiny two-mile long crescent of sand,
lying a few miles off
Queensland's northerly tip,
provides nesting sites
for half the entire population
of one of the world's
rarest sea turtles.
Flat-backed turtles are large,
over a metre long
but they have to be careful.
There are other giant
reptiles here too.
Salt-water crocodiles.
Every night throughout the year
there are flat-backs burying their eggs
all along this lonely stretch of sand.
Nine weeks later and things
are about to happen.
These eyes shining in the darkness
belong to night herons.
As if from nowhere, hundreds of birds
suddenly appear on the sand dunes.
Pelicans wait patiently.
Jabiru storks pace up and down.
Before long they see what
they've been waiting for.
Because these turtles lay
their eggs throughout the year,
the hatchlings emerge night after night
in a steady trickle of beak sized meals.
Pelican's broad beaks allow
them to dig out the hatchlings
before the herons can spear
them on the surface.
The surf may be hundreds of metres away
and at least a third of the tiny turtles
do not survive the journey.
And its not just the birds
that take them.
Crocodiles, sharks and hungry fish
are all waiting in the shallows.
In fact only one in every hundred
hatchlings will survive to adulthood.
Another beach, another continent,
and a very special night.
Here in Costa Rica there is a turtle which
has found a way of reducing these dangers.
When Ridley's turtles arrive
to lay their eggs
they don't come in tens or hundreds...
but in thousands.
Over the next six days around four hundred
thousand females will visit this beach.
At the peak time, five thousand
are coming and going each hour.
The beach gets so crowded that
they have to clamber over one another
to find a bare patch of sand
where they can dig a nest hole.
Forty million eggs are laid
in these few days.
So these turtles ensure
that six weeks later
when their hatchlings emerge
it's not just a trickle.
It's a flood.
On some nights, over two million
hatchlings race down to the sea together.
With so many appearing simultaneously,
the predators are overwhelmed and most
of the young turtles reach the sea safely.
Leaving the sea and emerging onto
land is hard enough for turtles.
It'd even harder for fish.
Each year for hundreds of miles
along the Newfoundland coast,
capelin throw themselves
onto the beaches.
At least a million tonnes of
fish floundering out of the water
a real gift for scavenging
eagles and gulls.
Odd though it may seem for a fish,
these capelin,
like the turtles, have also
come out of the sea to breed.
The males are trying to
fertilise the eggs
that the females are
depositing in the sand.
Like the Ridley's turtles,
they have synchronised their mass
laying with the tide.
In a few days it will be over.
Most of the capelin die but only after
they've left their eggs in the sand.
Other capelin populations
lay their eggs
in the ocean so why do the
Newfoundland fish spawn on land.
It seems that eggs deposited in
the beach may be safer
from predators and develop faster
than in colder waters out to sea.
But wherever they do so,
the huge spawning shoals
provide the concentration of food that
seabirds need when they assemble to breed.
Ninety five percent of the
world's seabirds nest together,
mostly in large spectacular colonies.
This is Funk Island forty miles
off the coast of Newfoundland
an isolated rock crammed
with breeding sea-birds.
This was the last breeding ground for the
flightless Great Auk, sadly now extinct.
Today it's still the world's
largest Guillemot colony.
Over a million of them share the
crowded island with 250,000 gannets.
It's not the lack of suitable sites
that causes the seabirds
to breed in such densities.
Here in the North Atlantic,
there's a wide choice of
empty coastline that
the birds could use.
The key factor limiting the size
and location of seabird colonies
seems to be the availability of food
in the surrounding ocean.
There are lots of hungry mouths to feed
and a constant demand for fish.
Throughout the long summer days
at colonies like funk,
There's a continual stream of birds,
heading out to the ocean to find food
and returning with full crops
to feed their young.
Gannets will travel up
to two hundred miles
from the colony on
a single foraging trip.
They are not fussy eaters
and will take everything
from tiny sand eels to herring.
Puffins, on the other hand,
are very particular about
what they eat and because they can
only fly short distances,
they only nest where there's a good
supply of suitable food close by.
One such place is the sea of Okhotsk
in far eastern Russia.
This is the island of Talan.
Throughout the long arctic winter,
it is encircled by ice.
But as spring approaches,
that begins to break up
and seabirds that have spent
the winter feeding out
on the open ocean far to
the south begin to return.
Its isolated position and steep cliffs
make Talan a perfect nesting site.
The Tufted Puffins arrive first.
These are the Pacific cousins of
our less spectacular Atlantic species.
Horned puffins soon follow.
In all, fourteen different species
return to Talan each spring
and in just a few weeks
the once silent cliffs
come alive to the calls of
4 million breeding seabirds.
This is a multi-storey avian city.
Assembling in these dense colonies after
having spent a largely solitary life
at sea provides the birds with
the social stimulation
that is the key to co-ordinating
their breeding.
By nesting and laying together
they ensure that
most of their chicks will leave
the nest at exactly the same time.
Just like the turtles this is the way
they spread the impact of predators.
The world's largest eagle.
Steller's sea eagle.
A third as big again as a golden.
Throughout the summer, the eagles
hunt in Talan's crowded colonies.
Riding on the updrafts,
they patrol the top of the cliffs,
looking out for any Kittiwake
that ventures too far from the rock face.
Suddenly the huge eagle stoops
with the aerial agility of a falcon.
Co-ordinated panic among the kittiwakes
confuses their attacker.
But the eagle doesn't give up.
And it has got one.
Another kind of seabird on Talan
has a particularly effective way
of defending itself against predators
but it doesn't appear until
an hour before sunset.
As if from nowhere, dense swarms of
seabirds suddenly arrive off-shore.
They're spent the day feeding far away,
where the sea ice has already broken up.
They are crested auklets,
hardly bigger than starlings.
A million of them return to Talan each
year to nest in its fields of boulders.
For an hour before sunset,
the hillsides comes alive
with huge flocks of circling auklets
They're nervous.
No one wants to be the first to land.
Auklets are very social when
they are back together at the coast.
One of the advantages of nesting
in such densities
may be the chance to share
information on good feeding sites.
It also gives them the
opportunity to court.
But perhaps most importantly,
there is safety in numbers.
Ravens and peregrines circle above
the scree slope every evening.
By taking off together,
the auklets hope to confuse the predators.
Eventually their persistence
pays off.
The birds that face the
greatest challenge in coming
to the coast to nest are
surely the penguins.
Unable to fly, they have no alternative
but to brave the immense waves.
Most penguins live in the southern ocean
and they have to accept being
hurled about by the surf.
Whatever the weather, the penguin parents
have to come back to feed their chicks.
A southern sea lion bull
he knows the penguins always use
the same traditional landing beach.
Having braved the thundering surf,
the penguins have to make a mad dash
across open rock to get to their nests.
Despite his massive size and
a body adapted for swimming,
the bull chases the penguins for forty
or fifty metres across the rocks.
Having caught his penguin, the sea lion
carries it out into deeper water where,
by violently thrashing the little body,
he skins his meal.
The seas around the Falklands are some
of the roughest in the world.
In spite of that, the southern ocean
is home to millions of tiny seabirds
hardly bigger than swallows-petrels.
Being so small they are very
vulnerable to the bad weather.
A severe storm can blow
them miles off course
and keep them away from
their nests for days.
But these birds have developed a very
effective solution to that problem.
They lay a rather special egg.
Most bird's eggs, left exposed for even
a few hours, will chill and never hatch.
But these eggs are different.
They can be left for several days
without incubation and remain undamaged...
...while the parents struggle
home through the storm.
Prions have also come up with
a good way to avoid most predators.
They never come back to the
coast until after dark.
These are Thin-billed Prions.
Their burrows honeycomb this
hillside in the Falklands.
It'd deserted throughout
the daylight hours...
...but as soon as it's dark
and difficult for airborne
predators to hunt...
...the prions return.
As soon as they land, they call.
The problem, of course...
...is finding your burrow
among all the others.
He's listening out for
his mate's call...
...and down he goes.
The Alaskan coast.
It's spring and the last of
the winter storms is subsiding.
The plankton in this sea is in
bloom again and just off shore,
humpback whales have
returned to feed.
For these huge animals, there is a real
risk in coming into such shallow water
and each year a good number
of them pay the price.
It is an ignominious ending
for an ageing whale.
But so much flesh will not go to waste.
A black bear emerges
cautiously from the woods.
Visitors to the coast that don't come to
breed, have usually come to scavenge.
A whole range of different animals
have learnt to exploit
the enormous quantity of food...
...that washes up everyday on
coastlines around the world.
But like so much at the coast
the quantity of flotsam
and jetsam is unpredictable.
Nobody can rely on it alone.
This carcass even attracted
a shy pack of wolves only too happy
to anoint themselves with the...
...scent of rotting whale.
It was months before the
scavengers finally
cleaned up all the meat
on this huge and...
...unpredictable gift from the sea.
Whales give birth to their young at sea
and so can spend their entire lives there.
Other marine mammals - one of that are
in fact distant cousins of bears
have to return... each year to
their ancestral home on land.
The high arctic
Here lives one of them... the walrus.
Walruses spend nearly
all their lives at sea,
but each year for just a few weeks...
...they have to return to the coast.
They seek out isolated beaches
like this one on Round Island in the...
...far northern Pacific.
Suitable sites like this,
free from bears, are so scarce...
...that at times as many as
fourteen thousand animals
will cram themselves on to this...
...one beach.
When they first emerge from
the sea the walrus are white.
That's because being warm-blooded
animals living in very cold ocean,
they conserve heat by...
...keeping their blood concentrated
in the core of their bodies.
On land it's warm enough for them
to allow their...
...outer blood vessels to dilate and
that turns their skin from white to pink.
Now they can moult the outer
layers of their skin,
rubbing themselves up
against the rocks.
But more than anything
else coming to land
brings the walrus relief
from having to spend energy
maintaining their body temperature
in an icy-cold ocean.
Heat conservation, in fact, may well
be the primary reason so many...
...sea mammals are forced to
return to the land each year.
The world's coldest seas
are in Antarctica.
Each spring, half the world's
Southern Elephant seals
return to the island
of South Georgia.
Elephant seals have particularly thick
insulation of blubber that keeps them warm.
For them breeding is the only
reason to leave the sea.
With temperatures down
to minus 20...
...and hundred mile an hour winds,
it can't be comfortable out on the beach,
but heat dissipates more
rapidly through water...
...than through air so even
in these conditions...
...their young which at first
don't have a thick coat
of blubber will be far
warmer on the land.
Once the males are established on the
beach the females soon follow.
Within just ten days the empty beach
fills up with six thousand elephant seals.
Almost immediately the females give
birth to pups sired the previous year.
Their milk is very rich and the pups
grow astonishingly quickly.
In just three weeks they turn form thin
bags of skin to fat balls of blubber.
As soon as they've given birth,
the females become sexually
receptive again...
...and it's now that the
advantages of breeding
in such dense colonies become clear.
Females can make their
choice from many males,
while successful males can
have access to lots of females.
But to gain that access and
control a harem of females,
the bull must be prepared to fight.
The larger the male, the louder the roar
and the more likely he is to win.
When males are well matched these bloody
battles will last twenty minutes or more.
Eventually, the loser retreats into
a stream already pink with his own blood.
These battles certainly help females
select the strongest bulls...
...but they bring great
dangers for the pups.
Each year, in the denser
parts of the colony,
a fifth of the pups are
crushed to death.
This is why it may
be better to mate
at the edge of the beach
close to the sea.
Less dominant males hide
in the surf.
They are waiting to try
and steal an illicit mating...
...with females as
they come and go.
This male knows he has been
spotted by the big bull
who claims all the females
on this part of the beach.
Breeding in groups can bring advantages
to pups as well as to adults.
Along the coast of Patagonia southern sea
lions breed together each year
in groups several hundred strong.
For the growing pups these colonies
act rather like a school.
The bonds and relationships
developed here on the beach
may be vital for the
rest of their lives.
Sea lions are very social animals
and as adults and young forage together,
they probably share...
...information about the location
of good feeding sites.
Conditions here could hardly be better
for the growing youngsters.
As the tide goes out it leaves behind
a selection of sheltered pools.
Perfect places for
learning to swim.
At high tide...
...it is easy for the pups to take their
first experimental dips in the surf.
A killer whale.
These young pups have never seen
anything like it before.
The Whales though are
very experienced.
Each year this same group turns
up along the coast
at precisely the same time
as the pups are starting to swim.
The whales need to surprise the pups,
so they have stopped calling
to one another and keep silent.
Speed is everything.
The whales do not take pups
that are out of the water,
but sometimes their momentum
drives them right up the beach
and then there's real danger
of getting stuck.
The whale has to thrash in this
frenzied way to get off the beach.
Most of the pups are taken into deep
water while they're still alive.
And there the whales - apparently.
Play with them.
Often an adult whale is joined
in the game by a youngster.
It may be learning how to grab a seal pup
before it risks a drive up the beach.
Whatever the reason the seal pup.
Still alive
is tossed back and forth
for over half an hour.
Even when the pup is dead, the whales'
sport is not completely over.
We can only speculate at the real reasons
behind this extraordinary behaviour.
But for the whales, the hunting
season is a short one.
Before long the pups learn to
stay well clear of the water
and the whales become less
and less successful.
After just two weeks, they move on.
The killing season is over.
That's how it often happens
along the coast.
Things are always changing.
They're never the same
for long in this,
the most dynamic of all
the ocean's habitats