The Blue Planet (2001): Season 1, Episode 8 - Coasts - full transcript
The boundary between land and sea is an exciting place, with seabirds, turtles, and marine mammals constantly coming and going.
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,
Iooking 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,
Iooking 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