Original subtitles

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