Coasts The Blue Planet

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 seagoing 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 to grab a few mouthfuls

before the next breaker comes pounding in.

Female iguanas feed only on the exposed rocks.

But the larger males swim and dive beneath the surface

to reach the weed.

They go as deep as ten metres.

For there, beyond the reach of the waves, they find the best fronds.

Being cold-blooded, they have to return to land after 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 eggs in burrows

and leave them there to hatch. To do THAT, they need nice, soft sand.

At the water's 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 come here spend most of their time elsewhere - in or above the ocean.

However, all seabirds have to come to land in order to lay their eggs.

After spending lonely months looking for food, they have to re-establish their social relationships.

Frigate birds display, and exchange nesting material.

Waved albatross dance.

The need to lay eggs on firm ground ties the albatross to the coast,

but parental responsibilities are shared - one looks after the egg,

and 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 1,500 miles to the tiny island of Ascension,

that lies bang in the middle of the Atlantic.

How they manage to navigate with accuracy

and find this tiny lump of rock - just seven miles wide - is a mystery.

But, each year, up to 5,000 turtles manage to do so

and then, close to the coast of Ascension, they mate.

Travelling to and from Ascension, and nesting here, takes six months.

Throughout that entire time, none of them feed at all.

After mating,

the female has to leave her natural element and haul herself onto land.

She does so at night, laying three or four times at 15-day intervals.

Then she swims back to the seas off Brazil.

She returns to this very same island throughout her life.

Remarkably, all the world's sea turtles return each 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 off Queensland's northerly tip,

provides nesting sites for half the entire population of one of the rarest turtles.

Flat-backed turtles are large - over a metre long.

They have to be careful. There are other giant reptiles here -

saltwater crocodiles.

Every night throughout the year,

flat-backs bury their eggs all along this lonely stretch of land.

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 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 each night in a steady trickle of beak-sized meals.

Pelicans' 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 a third of the tiny turtles do not survive the journey.

It's not just birds that take them.

Crocodiles, sharks and hungry fish are all waiting in the shallows.

Only one in every hundred hatchlings will survive to adulthood.

Another beach, another continent and a very special night.

In Costa Rica, there is a turtle which has found a way

to reduce these dangers. When Ridley's turtles arrive to lay their eggs, they don't come in hundreds,

but in thousands.

Over the next six days, around 400,000 females will visit this beach.

At the peak time, 5,000 are coming and going each hour.

The beach gets so crowded, they have to clamber to find a bare patch of sand where they can dig a nest hole.

40 million eggs are laid in these few days. 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 to the sea together.

With so many appearing at once, their 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's even harder for fish.

Each year, for hundreds of miles along the Newfoundland coast,

capelin throw themselves onto the beaches.

At least a million tons 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 come out of the sea to breed.

The males are trying to fertilise the eggs 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 them 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 left on the beach may be safer from predators and develop faster than in colder water.

Wherever they do so, the huge spawning shoals provide

the concentration of food that seabirds need when THEY assemble to breed.

95% of the world's seabirds

nest together, mostly in large, spectacular colonies.

This is Funk Island, 40 miles off the coast of Newfoundland -

an isolated rock crammed with breeding seabirds.

This was the last breeding ground for the flightless great auk, now extinct.

Today, it's still the world's largest guillemot colony -

over a million of them share the island with 250,000 gannets.

It's not the lack of suitable sites that causes the seabirds to breed in such densities.

In the North Atlantic, there's a wide choice of coastline they 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 days at colonies like Funk,

there's a continual stream of birds heading to the ocean to find food

and returning to feed their young.

Gannets travel up to 200 miles from the colony on one foraging trip.

They're not fussy eaters

and will take everything, from tiny sand eels to herring.

Puffins 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's encircled by ice.

As spring approaches, it breaks up,

and seabirds that have spent winter feeding on the ocean 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.

14 different species return 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 multistorey 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 chicks will leave the nest at the same time.

Like the turtles, this is the way they spread the impact of predators.

The world's largest eagle - Stellar's sea eagle -

as third as big again as a golden.

Throughout the summer, the eagles hunt in Talan's crowded colonies.

Riding on the updraughts, they patrol 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!

The birds that face the greatest challenge in coming to the coast to nest are surely the penguins.

Unable to fly, they have no choice but to brave the immense waves.

Most penguins live in the southern oceans, 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 beach.

The penguins now have to make a mad dash

across open rock to reach the nests.

Despite his massive size and a body adapted for swimming,

the bull chases the penguins for 40 or 50 metres across the rocks.

Having caught his penguin, the sea lion carries it out into deep water,

where, by violently thrashing the little body,

he skins his meal.

The Alaskan coast.

It's spring and the last of the winter storms is subsiding.

The plankton in the sea is in bloom again and, just offshore,

humpback whales have returned to feed.

For these huge animals, there's a real risk of coming into such shallow water,

and each year, a good number of them pay the price.

It's 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 animals exploit the enormous quantity of food that washes up every day

on the coastlines around the world.

But 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 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 - ones that are in fact distant cousins of bears -

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 northern Pacific. Sites like this - free from bears - are so scarce

that, at times, as many as 14,000 animals will cram themselves onto this one beach.

When they first emerge from the sea, the walrus are white.

That's because, being warm-blooded in a cold ocean, they conserve heat

by keeping blood concentrated in the core of their bodies.

On land, it's warm enough to allow their outer blood vessels to dilate,

and that turns their skin 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 spending 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 a 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 100mph winds, it can't be comfortable on the beach,

but heat dissipates more rapidly through water, 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 6,000 elephant seals.

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 from thin bags of skin

to fat balls of blubber.

As soon as they've given birth, the females become sexually receptive again.

Now 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,

a 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 20 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're waiting to steal an illicit mating, as the females come and go.

This male knows he's been spotted by the big bull, who claims all the females on this part of the beach.

Breeding in groups brings advantages to pups as well as to adults.

On 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 developed here on the beach may be vital for the rest of their lives.

Sea lions are social animals and, as adults and young forage together,

they share information about the location of good feeding sites.

Conditions could hardly be better for the youngsters.

As the tide goes out, it leaves a selection of sheltered pools.

Perfect places for learning to swim.

At high tide, it's easy for the pups to take their first dips in the surf.

A killer whale.

These pups have never seen anything like it before.

The whales, though, are experienced.

Each year, this same group turns up along the coast at the same time as the pups are starting to swim.

The whales need to surprise the pups, so they've 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 up the beach. 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 to deep water while they're still alive.

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 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 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 always change.

They're never the same for long

in this, the most dynamic of all the oceans' habitats.

Orcas, or killer whales, are highly intelligent social animals

that hunt in close family groups.

For Blue Planet, we filmed two very different pods of killer whales,

one hunting off the Californian coast, the other in Argentina.

Each had a totally different hunting technique

and filming their behaviour required not only patience

but an understanding of killer whale culture.

Only by getting under the skins of whales had we any chance of predicting what they would do next.

This windswept beach in Argentina is visited each year

by a particular pod of killer whales that come to prey on sea lion pups.

I was going to stand a much greater chance of filming the orcas

attacking young sea lions if I knew them as individuals.

Fortunately, park guard, Roberto Bubas, had watched orcas for many years

and could tell me not only what sex they were

but which was most likely to attack.

The problem was that when I first arrived

they weren't behaving as we expected.

They weren't attacking the sealion colonies. We had a long wait ahead.

Much further north, off California's Pacific coast,

a Blue Planet team spent two seasons working with another group of killer whales.

Yearly, this pod patrols the waters off Monterey Bay, San Francisco,

looking for very large prey indeed -

Gray whales migrating north in search of rich feeding grounds.

The main challenge was just finding the killer whales.

A plane searched round the clock,

giving directions to a boat-based team.

This was to prove one of the most ambitious of Blue Planet's missions.

Our team was advised by marine biologist, Nancy Black,

who had only witnessed one complete killer whale attack in 14 years of research at Monterey Bay.

Even when they were lucky enough to track down the killer whales,

rough weather made filming very difficult.

Frustrating! We followed these killer whales,

but as you can see, the sea's just got up.

It's 30, 35 knots and we couldn't keep up with them.

We've been 16 days out on the water - we've another six to go.

We're not gonna see it.

We're not really hitting big time. It's a funny kind of filming, its...frustrating!

Day after day at sea, with not a single frame of film to show for it.

Andy the dog is going to tell you what we saw... See? Nothing.

Back in Argentina, after two weeks of waiting,

Simon noticed a change in the behaviour of his killer whales.

The group of female orcas and their young, who had a reputation for being fine hunters,

at last moved towards the sea lion colony where our hide was situated.

The problem now was predicting when an attack might occur.

With Roberto's help, I could choose an individual,

and film it with high speed cameras that would reveal the action.

Ah! The film ran out at a crucial moment.

It's a real risk when you're running film through a camera at high speed.

But with careful timing and good fortune, everything came together.

LAUGHING

'After four weeks of working from dawn to dusk,

'the emotional release of finally witnessing this phenomenal behaviour

-'is indescribable.'

-INAUDIBLE

Back in California, things were also looking up.

Grey whale mothers and their calves had started to arrive at Monterey

on their migration north.

These are the killer whales' favoured prey.

These guys are pretty impressive,

It looks like they're heading somewhere, so fingers crossed.

Doug's hunch was right.

The killers kept up the hunt for five hours

until the calf was so exhausted, the mother was forced to stop.

And we had to watch as the pod came in to finish off the calf,

just a few metres from our inflatable.

If they'd taken a mind to it, they could have flipped us over.

On the other hand, I think they were concentrating on the whale.

We were able to get closer and not interfere.

It's just so completely exciting,

being beside it and almost filming down this animal's blowholes.

The whole thing is just turmoil and you really get a feeling for what the whale is going through.

It was only after the killer whales had moved on

that Doug felt it safe enough to dive in with the camera.

And I do remember it being almost spooky and eerie going underwater

and seeing the wounds on that baby whale

and feeling you should be looking over your shoulder,

to see if the big boys were coming back.

You're left with just an immense sense of relief,

which leaves you completely emotionally drained.

Subtitles by BBC

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