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The coast - the frontier
between land and sea
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00:00:50,783 --> 00:00:54,963
This is the most dynamic
of all the ocean habitats
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00:00:54,964 --> 00:00:58,092
The challenge here is
to survive change
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00:00:58,093 --> 00:01:02,254
Extreme change
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00:01:29,408 --> 00:01:33,579
Cape Douglas, on the most
westerly of the Galapagos islands,
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00:01:33,580 --> 00:01:37,760
totally unprotected from the massive
rollers of the Pacific Ocean
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and one of the roughest
coastlines in the world
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The marine iguanas of the Galapagos
are the world's only sea-going lizards
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00:02:32,039 --> 00:02:36,200
Seaweed is all they eat,
but doing so is a dangerous business
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00:02:39,349 --> 00:02:42,477
The local crabs have
become specially flattened,
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00:02:42,478 --> 00:02:45,605
minimising the effect
of the pounding waves
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00:02:45,606 --> 00:02:49,778
And the iguanas have huge
claws to grip the rocks
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This seaweed really is fast food
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There are only a few seconds
in which to grab a few mouthfuls
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before the next breaker
comes pounding in
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00:03:08,579 --> 00:03:11,707
Female iguanas feed
only on the exposed rocks,
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00:03:11,708 --> 00:03:15,869
but the males which are larger swim and
dive beneath the surface to reach the weed
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00:03:21,103 --> 00:03:23,188
They go as deep as ten metres,
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for there beyond the destructive reach
of the waves, they find the best fronds
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00:03:29,456 --> 00:03:32,584
Being cold-blooded they
have to return to land
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after about ten minutes or
so to warm up again in the sun
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Finding food is not the only
challenge for coastal residents
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These rocky shores are hardly
a safe place to lay their eggs
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00:04:01,815 --> 00:04:04,942
and each year the marine iguanas
have to journey inland
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00:04:04,943 --> 00:04:09,104
to find a more suitable one
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00:04:11,210 --> 00:04:15,381
The females lay their eggs in burrows
and leave them there to hatch,
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and to do that they
need nice soft sand
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00:04:29,991 --> 00:04:34,172
Down at the water edge, it was easy
to escape danger in rocky crevices,
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but up here the females
are dangerously exposed
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A Galapagos hawk
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The lizards don't give up
without a struggle
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00:05:37,847 --> 00:05:42,008
These hawks stay on the coast all year
But they are exceptional
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00:05:43,061 --> 00:05:47,242
The majority of the birds
that frequent this frontier
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00:05:47,243 --> 00:05:51,413
spend most of their time elsewhere
- in or above the open ocean
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However all seabirds have to come
to land in order to lay their eggs
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And after spending many lonely
months searching the ocean for food,
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00:06:00,810 --> 00:06:04,970
they have to re-establish
their social relationships
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00:06:07,077 --> 00:06:11,238
Frigate birds display and
exchange nesting material
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00:06:15,419 --> 00:06:19,591
Waved albatross dance
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00:06:30,039 --> 00:06:34,200
The need to lay their egg on firm ground
ties the albatross to the coast
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00:06:36,296 --> 00:06:38,391
but parental responsibilities
are shared
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While one looks after the egg,
...the other can go off to feed
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00:07:11,794 --> 00:07:15,964
The need to breed brings
many different animals
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to the coast each year
for a few weeks
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00:07:19,104 --> 00:07:23,274
Male sea turtles spend all
their lives at sea, but the females,
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00:07:23,275 --> 00:07:27,436
like birds, must come to
land to lay their eggs
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00:07:33,713 --> 00:07:37,874
To do that green turtles that live
and feed off the coast of Brazil
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00:07:38,927 --> 00:07:43,099
swim fifteen hundred miles to the
tiny island of Ascension
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that lies bang in the middle
of the Atlantic Ocean
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00:07:58,762 --> 00:08:02,942
Exactly how they manage to
navigate with such accuracy
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00:08:02,943 --> 00:08:07,104
and find this tiny lump of rock,
just seven miles wide is a mystery
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00:08:11,296 --> 00:08:15,457
But each year up to five thousand
turtles manage to do so and then,
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close to the coast of Ascension,
they mate
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00:08:19,639 --> 00:08:23,810
Travelling to and from Ascension and
nesting here can take up to six months
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00:08:25,906 --> 00:08:30,067
and throughout that entire time,
none of them feed at all
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00:08:33,216 --> 00:08:36,343
After mating a female has to
leave her natural element
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00:08:36,344 --> 00:08:40,515
and haul herself up onto land
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She does so at night,
laying about three or four times
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at around fifteen day intervals
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00:08:46,783 --> 00:08:50,953
After that she then swims all the way
back to the seas off Brazil
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00:08:50,954 --> 00:08:55,135
She returns to this very same
island throughout her life
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00:08:55,136 --> 00:08:59,297
Remarkably, all the world's sea turtles
return year after year
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to just a few traditional
breeding sites
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Crab Island, in Australia,
is one of them
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00:09:10,788 --> 00:09:13,926
This tiny two-mile long crescent of sand,
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00:09:13,927 --> 00:09:17,055
lying a few miles off
Queensland's northerly tip,
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provides nesting sites
for half the entire population
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00:09:21,227 --> 00:09:25,408
of one of the world's
rarest sea turtles
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00:09:25,409 --> 00:09:28,536
Flat-backed turtles are large,
over a metre long
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- but they have to be careful
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00:09:30,623 --> 00:09:33,750
There are other giant
reptiles here too
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Salt-water crocodiles
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Every night throughout the year
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there are flat-backs burying their eggs
all along this lonely stretch of sand
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00:10:01,938 --> 00:10:06,099
Nine weeks later and things
are about to happen
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00:10:13,419 --> 00:10:17,591
These eyes shining in the darkness
belong to night herons
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00:10:23,858 --> 00:10:28,029
As if from nowhere, hundreds of birds
suddenly appear on the sand dunes
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00:10:29,082 --> 00:10:33,253
Pelicans wait patiently
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00:10:33,254 --> 00:10:37,414
Jabiru storks pace up and down
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00:10:40,564 --> 00:10:44,725
Before long they see what
they've been waiting for.
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00:11:08,751 --> 00:11:11,878
Because these turtles lay
their eggs throughout the year,
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the hatchlings emerge night after night
in a steady trickle of beak sized meals
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00:11:39,013 --> 00:11:43,194
Pelican's broad beaks allow
them to dig out the hatchlings
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before the herons can spear
them on the surface
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00:11:51,548 --> 00:11:53,632
The surf may be hundreds of metres away
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and at least a third of the tiny turtles
do not survive the journey
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00:11:59,890 --> 00:12:04,061
And its not just the birds
that take them
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00:12:07,200 --> 00:12:11,381
Crocodiles, sharks and hungry fish
are all waiting in the shallows
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00:12:11,382 --> 00:12:15,543
In fact only one in every hundred
hatchlings will survive to adulthood
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00:12:25,992 --> 00:12:30,152
Another beach, another continent,
and a very special night
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00:12:31,206 --> 00:12:35,377
Here in Costa Rica there is a turtle which
has found a way of reducing these dangers
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00:12:37,473 --> 00:12:40,600
When Ridley's turtles arrive
to lay their eggs
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00:12:40,601 --> 00:12:44,773
they don't come in tens or hundreds...
but in thousands
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00:12:46,869 --> 00:12:51,030
Over the next six days around four hundred
thousand females will visit this beach
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00:12:54,179 --> 00:12:58,340
At the peak time, five thousand
are coming and going each hour
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00:12:59,393 --> 00:13:03,573
The beach gets so crowded that
they have to clamber over one another
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00:13:03,574 --> 00:13:07,735
to find a bare patch of sand
where they can dig a nest hole
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00:13:10,874 --> 00:13:14,012
Forty million eggs are laid
in these few days
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00:13:14,013 --> 00:13:17,140
So these turtles ensure
that six weeks later
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00:13:17,141 --> 00:13:21,302
when their hatchlings emerge
it's not just a trickle
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It's a flood
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On some nights, over two million
hatchlings race down to the sea together
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With so many appearing simultaneously,
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the predators are overwhelmed and most
of the young turtles reach the sea safely
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00:14:12,462 --> 00:14:16,643
Leaving the sea and emerging onto
land is hard enough for turtles
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00:14:16,644 --> 00:14:20,805
It'd even harder for fish
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00:14:27,083 --> 00:14:31,253
Each year for hundreds of miles
along the Newfoundland coast,
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capelin throw themselves
onto the beaches
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At least a million tonnes of
fish floundering out of the water
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00:15:07,783 --> 00:15:11,955
- a real gift for scavenging
eagles and gulls
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00:15:31,799 --> 00:15:34,927
Odd though it may seem for a fish,
these capelin,
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00:15:34,928 --> 00:15:39,089
like the turtles, have also
come out of the sea to breed
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The males are trying to
fertilise the eggs
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00:15:54,762 --> 00:15:58,932
that the females are
depositing in the sand
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00:15:58,933 --> 00:15:59,975
Like the Ridley's turtles,
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they have synchronised their mass
laying with the tide
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In a few days it will be over
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00:16:08,329 --> 00:16:12,500
Most of the capelin die but only after
they've left their eggs in the sand
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00:16:16,682 --> 00:16:18,766
Other capelin populations
lay their eggs
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00:16:18,767 --> 00:16:22,939
in the ocean so why do the
Newfoundland fish spawn on land
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00:16:23,992 --> 00:16:27,119
It seems that eggs deposited in
the beach may be safer
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from predators and develop faster
than in colder waters out to sea
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00:16:35,473 --> 00:16:38,601
But wherever they do so,
the huge spawning shoals
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provide the concentration of food that
seabirds need when they assemble to breed
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00:16:47,997 --> 00:16:52,168
Ninety five percent of the
world's seabirds nest together,
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mostly in large spectacular colonies
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00:16:58,436 --> 00:17:02,597
This is Funk Island forty miles
off the coast of Newfoundland
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00:17:03,660 --> 00:17:07,821
- an isolated rock crammed
with breeding sea-birds
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00:17:16,184 --> 00:17:20,345
This was the last breeding ground for the
flightless Great Auk, sadly now extinct
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00:17:22,441 --> 00:17:26,622
Today it's still the world's
largest Guillemot colony
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00:17:26,623 --> 00:17:30,784
Over a million of them share the
crowded island with 250,000 gannets
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00:17:34,976 --> 00:17:37,060
It's not the lack of suitable sites
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that causes the seabirds
to breed in such densities
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00:17:41,233 --> 00:17:44,360
Here in the North Atlantic,
there's a wide choice of
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empty coastline that
the birds could use
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00:17:47,500 --> 00:17:50,627
The key factor limiting the size
and location of seabird colonies
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seems to be the availability of food
in the surrounding ocean
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00:18:01,067 --> 00:18:05,228
There are lots of hungry mouths to feed
and a constant demand for fish
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00:18:12,548 --> 00:18:15,676
Throughout the long summer days
at colonies like funk,
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There's a continual stream of birds,
heading out to the ocean to find food
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00:18:20,901 --> 00:18:25,062
and returning with full crops
to feed their young
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00:18:33,425 --> 00:18:36,553
Gannets will travel up
to two hundred miles
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00:18:36,554 --> 00:18:39,691
from the colony on
a single foraging trip
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00:18:39,692 --> 00:18:42,820
They are not fussy eaters
and will take everything
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00:18:42,821 --> 00:18:46,982
- from tiny sand eels to herring
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00:18:59,527 --> 00:19:01,611
Puffins, on the other hand,
are very particular about
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what they eat and because they can
only fly short distances,
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they only nest where there's a good
supply of suitable food close by
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00:19:17,265 --> 00:19:21,436
One such place is the sea of Okhotsk
in far eastern Russia
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This is the island of Talan
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00:19:30,842 --> 00:19:35,012
Throughout the long arctic winter,
it is encircled by ice
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00:19:35,013 --> 00:19:38,141
But as spring approaches,
that begins to break up
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00:19:38,142 --> 00:19:41,280
and seabirds that have spent
the winter feeding out
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on the open ocean far to
the south begin to return
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00:19:50,676 --> 00:19:54,837
Its isolated position and steep cliffs
make Talan a perfect nesting site
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00:19:59,019 --> 00:20:01,114
The Tufted Puffins arrive first
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00:20:01,115 --> 00:20:05,276
These are the Pacific cousins of
our less spectacular Atlantic species
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00:20:10,500 --> 00:20:14,681
Horned puffins soon follow
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00:20:14,682 --> 00:20:18,852
In all, fourteen different species
return to Talan each spring
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00:20:18,853 --> 00:20:23,034
and in just a few weeks
the once silent cliffs
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come alive to the calls of
4 million breeding seabirds
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00:20:31,377 --> 00:20:35,548
This is a multi-storey avian city
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Assembling in these dense colonies after
having spent a largely solitary life
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at sea provides the birds with
the social stimulation
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00:20:52,254 --> 00:20:56,426
that is the key to co-ordinating
their breeding
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00:20:58,522 --> 00:21:01,649
By nesting and laying together
they ensure that
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00:21:01,650 --> 00:21:05,831
most of their chicks will leave
the nest at exactly the same time
168
00:21:05,832 --> 00:21:09,992
Just like the turtles this is the way
they spread the impact of predators
169
00:21:14,185 --> 00:21:18,355
The world's largest eagle
- Steller's sea eagle
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00:21:18,356 --> 00:21:22,517
A third as big again as a golden
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00:21:24,623 --> 00:21:28,784
Throughout the summer, the eagles
hunt in Talan's crowded colonies
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00:21:41,318 --> 00:21:45,499
Riding on the updrafts,
they patrol the top of the cliffs,
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00:21:45,500 --> 00:21:49,661
Iooking out for any Kittiwake
that ventures too far from the rock face
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00:21:55,939 --> 00:22:00,099
Suddenly the huge eagle stoops
with the aerial agility of a falcon
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00:22:09,506 --> 00:22:13,666
Co-ordinated panic among the kittiwakes
confuses their attacker
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00:22:29,340 --> 00:22:33,501
But the eagle doesn't give up
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00:22:43,949 --> 00:22:48,110
And it has got one
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00:23:00,655 --> 00:23:04,816
Another kind of seabird on Talan
has a particularly effective way
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00:23:05,869 --> 00:23:07,954
of defending itself against predators
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00:23:07,955 --> 00:23:12,126
- but it doesn't appear until
an hour before sunset
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00:23:16,308 --> 00:23:20,479
As if from nowhere, dense swarms of
seabirds suddenly arrive off-shore
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00:23:26,746 --> 00:23:30,918
They're spent the day feeding far away,
where the sea ice has already broken up
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00:23:33,014 --> 00:23:37,184
They are crested auklets,
hardly bigger than starlings
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00:23:37,185 --> 00:23:41,356
A million of them return to Talan each
year to nest in its fields of boulders
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00:23:49,709 --> 00:23:52,847
For an hour before sunset,
the hillsides comes alive
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00:23:52,848 --> 00:23:57,018
with huge flocks of circling auklets
They're nervous
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00:23:57,019 --> 00:24:01,180
No one wants to be the first to land
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00:24:07,458 --> 00:24:10,585
Auklets are very social when
they are back together at the coast
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00:24:10,586 --> 00:24:13,724
One of the advantages of nesting
in such densities
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00:24:13,725 --> 00:24:17,895
may be the chance to share
information on good feeding sites
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00:24:17,896 --> 00:24:22,057
It also gives them the
opportunity to court
192
00:24:26,249 --> 00:24:30,410
But perhaps most importantly,
there is safety in numbers
193
00:24:36,687 --> 00:24:40,848
Ravens and peregrines circle above
the scree slope every evening
194
00:24:57,565 --> 00:25:01,725
By taking off together,
the auklets hope to confuse the predators
195
00:25:34,094 --> 00:25:38,265
Eventually their persistence
pays off
196
00:25:47,671 --> 00:25:50,799
The birds that face the
greatest challenge in coming
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00:25:50,800 --> 00:25:54,961
to the coast to nest are
surely the penguins
198
00:26:07,506 --> 00:26:11,666
Unable to fly, they have no alternative
but to brave the immense waves
199
00:26:25,244 --> 00:26:27,339
Most penguins live in the southern ocean
200
00:26:27,340 --> 00:26:31,501
and they have to accept being
hurled about by the surf
201
00:26:50,303 --> 00:26:54,463
Whatever the weather, the penguin parents
have to come back to feed their chicks
202
00:27:05,955 --> 00:27:08,040
A southern sea lion bull
203
00:27:08,041 --> 00:27:12,212
- he knows the penguins always use
the same traditional landing beach
204
00:27:17,436 --> 00:27:19,531
Having braved the thundering surf,
205
00:27:19,532 --> 00:27:23,693
the penguins have to make a mad dash
across open rock to get to their nests
206
00:27:46,666 --> 00:27:50,847
Despite his massive size and
a body adapted for swimming,
207
00:27:50,848 --> 00:27:55,009
the bull chases the penguins for forty
or fifty metres across the rocks
208
00:28:50,340 --> 00:28:54,511
Having caught his penguin, the sea lion
carries it out into deeper water where,
209
00:28:55,565 --> 00:28:59,725
by violently thrashing the little body,
he skins his meal
210
00:29:10,174 --> 00:29:14,335
The seas around the Falklands are some
of the roughest in the world
211
00:29:16,442 --> 00:29:20,602
In spite of that, the southern ocean
is home to millions of tiny seabirds
212
00:29:21,656 --> 00:29:24,794
hardly bigger than swallows-petrels
213
00:29:24,795 --> 00:29:27,922
Being so small they are very
vulnerable to the bad weather
214
00:29:27,923 --> 00:29:31,050
A severe storm can blow
them miles off course
215
00:29:31,051 --> 00:29:35,232
and keep them away from
their nests for days
216
00:29:35,233 --> 00:29:39,394
But these birds have developed a very
effective solution to that problem
217
00:29:42,533 --> 00:29:45,671
They lay a rather special egg
218
00:29:45,672 --> 00:29:49,832
Most bird's eggs, left exposed for even
a few hours, will chill and never hatch
219
00:29:51,928 --> 00:29:54,013
But these eggs are different
220
00:29:54,014 --> 00:29:57,152
They can be left for several days
without incubation and remain undamaged...
221
00:29:57,153 --> 00:30:01,314
...while the parents struggle
home through the storm
222
00:30:05,495 --> 00:30:09,667
Prions have also come up with
a good way to avoid most predators
223
00:30:10,720 --> 00:30:14,881
They never come back to the
coast until after dark
224
00:30:16,987 --> 00:30:20,115
These are Thin-billed Prions
225
00:30:20,116 --> 00:30:24,286
Their burrows honeycomb this
hillside in the Falklands
226
00:30:24,287 --> 00:30:26,371
It'd deserted throughout
the daylight hours...
227
00:30:26,372 --> 00:30:28,467
...but as soon as it's dark
228
00:30:28,468 --> 00:30:31,596
and difficult for airborne
predators to hunt...
229
00:30:31,597 --> 00:30:35,758
...the prions return
230
00:30:40,993 --> 00:30:45,153
As soon as they land, they call
231
00:30:49,345 --> 00:30:50,387
The problem, of course...
232
00:30:50,388 --> 00:30:54,549
...is finding your burrow
among all the others
233
00:30:55,602 --> 00:30:59,783
He's listening out for
his mate's call...
234
00:30:59,784 --> 00:31:03,945
...and down he goes.
235
00:31:09,180 --> 00:31:11,264
The Alaskan coast
236
00:31:11,265 --> 00:31:15,426
It's spring and the last of
the winter storms is subsiding
237
00:31:18,565 --> 00:31:22,746
The plankton in this sea is in
bloom again and just off shore,
238
00:31:22,747 --> 00:31:26,907
humpback whales have
returned to feed
239
00:31:32,142 --> 00:31:36,303
For these huge animals, there is a real
risk in coming into such shallow water
240
00:31:37,356 --> 00:31:41,528
and each year a good number
of them pay the price
241
00:31:46,752 --> 00:31:49,879
It is an ignominious ending
for an ageing whale
242
00:31:49,880 --> 00:31:54,052
But so much flesh will not go to waste
243
00:31:55,105 --> 00:31:59,266
A black bear emerges
cautiously from the woods
244
00:32:08,672 --> 00:32:12,843
Visitors to the coast that don't come to
breed, have usually come to scavenge
245
00:32:14,939 --> 00:32:18,067
A whole range of different animals
have learnt to exploit
246
00:32:18,068 --> 00:32:20,152
the enormous quantity of food...
247
00:32:20,153 --> 00:32:24,324
.....that washes up everyday on
coastlines around the world
248
00:32:25,378 --> 00:32:29,548
But like so much at the coast
the quantity of flotsam
249
00:32:29,549 --> 00:32:31,634
and jetsam is unpredictable
250
00:32:31,635 --> 00:32:35,806
Nobody can rely on it alone
251
00:32:38,945 --> 00:32:43,105
This carcass even attracted
a shy pack of wolves only too happy
252
00:32:44,169 --> 00:32:45,211
to anoint themselves with the...
253
00:32:45,212 --> 00:32:49,373
...scent of rotting whale
254
00:32:52,512 --> 00:32:54,607
It was months before the
scavengers finally
255
00:32:54,608 --> 00:32:57,735
cleaned up all the meat
on this huge and...
256
00:32:57,736 --> 00:33:01,897
...unpredictable gift from the sea
257
00:33:07,132 --> 00:33:11,293
Whales give birth to their young at sea
and so can spend their entire lives there
258
00:33:13,389 --> 00:33:17,569
Other marine mammals - one of that are
in fact distant cousins of bears
259
00:33:17,570 --> 00:33:21,731
- have to return... each year to
their ancestral home on land
260
00:33:28,009 --> 00:33:32,170
The high arctic
Here lives one of them...the walrus
261
00:33:42,619 --> 00:33:45,756
Walruses spend nearly
all their lives at sea,
262
00:33:45,757 --> 00:33:47,842
but each year for just a few weeks...
263
00:33:47,843 --> 00:33:52,004
...they have to return to the coast.
264
00:33:53,057 --> 00:33:56,195
They seek out isolated beaches
like this one on Round Island in the...
265
00:33:56,196 --> 00:33:59,323
...far northern Pacific
266
00:33:59,324 --> 00:34:03,495
Suitable sites like this,
free from bears, are so scarce...
267
00:34:03,496 --> 00:34:06,633
...that at times as many as
fourteen thousand animals
268
00:34:06,634 --> 00:34:08,719
will cram themselves on to this...
269
00:34:08,720 --> 00:34:12,881
...one beach
270
00:34:19,159 --> 00:34:22,286
When they first emerge from
the sea the walrus are white
271
00:34:22,287 --> 00:34:26,457
That's because being warm-blooded
animals living in very cold ocean,
272
00:34:26,458 --> 00:34:29,596
they conserve heat by...
273
00:34:29,597 --> 00:34:33,767
...keeping their blood concentrated
in the core of their bodies
274
00:34:33,768 --> 00:34:36,896
On land it's warm enough for them
to allow their...
275
00:34:36,897 --> 00:34:41,068
...outer blood vessels to dilate and
that turns their skin from white to pink
276
00:34:51,517 --> 00:34:54,644
Now they can moult the outer
layers of their skin,
277
00:34:54,645 --> 00:34:58,806
rubbing themselves up
against the rocks
278
00:35:00,913 --> 00:35:04,040
But more than anything
else coming to land
279
00:35:04,041 --> 00:35:07,168
brings the walrus relief
from having to spend energy
280
00:35:07,169 --> 00:35:11,341
maintaining their body temperature
in an icy-cold ocean
281
00:35:15,522 --> 00:35:18,650
Heat conservation, in fact, may well
be the primary reason so many...
282
00:35:18,651 --> 00:35:22,822
...sea mammals are forced to
return to the land each year
283
00:35:29,089 --> 00:35:33,260
The world's coldest seas
are in Antarctica
284
00:35:34,314 --> 00:35:37,441
Each spring, half the world's
Southern Elephant seals
285
00:35:37,442 --> 00:35:41,623
return to the island
of South Georgia
286
00:35:41,624 --> 00:35:45,785
Elephant seals have particularly thick
insulation of blubber that keeps them warm
287
00:35:46,838 --> 00:35:50,999
For them breeding is the only
reason to leave the sea
288
00:35:57,276 --> 00:35:59,361
With temperatures down
to minus 20...
289
00:35:59,362 --> 00:36:03,533
...and hundred mile an hour winds,
it can't be comfortable out on the beach,
290
00:36:04,586 --> 00:36:06,671
but heat dissipates more
rapidly through water...
291
00:36:06,672 --> 00:36:10,842
...than through air so even
in these conditions...
292
00:36:10,843 --> 00:36:13,981
...their young which at first
don't have a thick coat
293
00:36:13,982 --> 00:36:18,152
of blubber will be far
warmer on the land
294
00:36:18,153 --> 00:36:22,314
Once the males are established on the
beach the females soon follow
295
00:36:27,549 --> 00:36:31,710
Within just ten days the empty beach
fills up with six thousand elephant seals
296
00:36:35,902 --> 00:36:40,063
Almost immediately the females give
birth to pups sired the previous year
297
00:36:51,555 --> 00:36:55,726
Their milk is very rich and the pups
grow astonishingly quickly
298
00:37:04,089 --> 00:37:08,250
In just three weeks they turn form thin
bags of skin to fat balls of blubber
299
00:37:12,432 --> 00:37:13,473
As soon as they've given birth,
300
00:37:13,474 --> 00:37:16,612
the females become sexually
receptive again...
301
00:37:16,613 --> 00:37:19,741
...and it's now that the
advantages of breeding
302
00:37:19,742 --> 00:37:22,869
in such dense colonies become clear
303
00:37:22,870 --> 00:37:24,965
Females can make their
choice from many males,
304
00:37:24,966 --> 00:37:29,127
while successful males can
have access to lots of females
305
00:37:36,447 --> 00:37:40,618
But to gain that access and
control a harem of females,
306
00:37:40,619 --> 00:37:44,779
the bull must be prepared to fight
307
00:38:05,667 --> 00:38:09,838
The larger the male, the louder the roar
and the more likely he is to win
308
00:38:21,330 --> 00:38:25,491
When males are well matched these bloody
battles will last twenty minutes or more
309
00:38:47,421 --> 00:38:51,592
Eventually, the loser retreats into
a stream already pink with his own blood
310
00:39:05,170 --> 00:39:09,350
These battles certainly help females
select the strongest bulls...
311
00:39:09,351 --> 00:39:13,512
...but they bring great
dangers for the pups.
312
00:39:22,918 --> 00:39:25,003
Each year, in the denser
parts of the colony,
313
00:39:25,004 --> 00:39:29,174
a fifth of the pups are
crushed to death
314
00:39:29,175 --> 00:39:32,313
This is why it may
be better to mate
315
00:39:32,314 --> 00:39:36,475
at the edge of the beach
close to the sea
316
00:39:40,667 --> 00:39:43,794
Less dominant males hide
in the surf
317
00:39:43,795 --> 00:39:46,923
They are waiting to try
and steal an illicit mating...
318
00:39:46,924 --> 00:39:51,084
...with females as
they come and go
319
00:39:54,234 --> 00:39:56,318
This male knows he has been
spotted by the big bull
320
00:39:56,319 --> 00:40:00,480
who claims all the females
on this part of the beach
321
00:41:06,260 --> 00:41:10,421
Breeding in groups can bring advantages
to pups as well as to adults
322
00:41:17,742 --> 00:41:21,903
Along the coast of Patagonia southern sea
lions breed together each year
323
00:41:22,956 --> 00:41:27,136
in groups several hundred strong
324
00:41:27,137 --> 00:41:31,308
For the growing pups these colonies
act rather like a school
325
00:41:31,309 --> 00:41:34,436
The bonds and relationships
developed here on the beach
326
00:41:34,437 --> 00:41:37,575
may be vital for the
rest of their lives
327
00:41:37,576 --> 00:41:41,737
Sea lions are very social animals
and as adults and young forage together,
328
00:41:42,790 --> 00:41:43,832
they probably share...
329
00:41:43,833 --> 00:41:48,004
...information about the location
of good feeding sites
330
00:41:50,100 --> 00:41:54,261
Conditions here could hardly be better
for the growing youngsters
331
00:41:55,314 --> 00:41:59,485
As the tide goes out it leaves behind
a selection of sheltered pools
332
00:42:01,581 --> 00:42:05,742
Perfect places for
learning to swim
333
00:42:40,207 --> 00:42:41,249
At high tide...
334
00:42:41,250 --> 00:42:45,411
...it is easy for the pups to take their
first experimental dips in the surf
335
00:43:21,961 --> 00:43:26,131
A killer whale
336
00:43:26,132 --> 00:43:30,293
These young pups have never seen
anything like it before
337
00:43:42,838 --> 00:43:45,966
The Whales though are
very experienced
338
00:43:45,967 --> 00:43:49,094
Each year this same group turns
up along the coast
339
00:43:49,095 --> 00:43:53,266
at precisely the same time
as the pups are starting to swim
340
00:44:03,715 --> 00:44:05,800
The whales need to surprise the pups,
341
00:44:05,801 --> 00:44:09,962
so they have stopped calling
to one another and keep silent
342
00:44:19,368 --> 00:44:23,539
Speed is everything
343
00:44:25,635 --> 00:44:28,762
The whales do not take pups
that are out of the water,
344
00:44:28,763 --> 00:44:31,891
but sometimes their momentum
drives them right up the beach
345
00:44:31,892 --> 00:44:36,063
and then there's real danger
of getting stuck
346
00:46:13,149 --> 00:46:17,309
The whale has to thrash in this
frenzied way to get off the beach
347
00:46:18,373 --> 00:46:22,543
Most of the pups are taken into deep
water while they're still alive
348
00:46:22,544 --> 00:46:26,705
And there the whales - apparently
- play with them
349
00:46:50,731 --> 00:46:54,902
Often an adult whale is joined
in the game by a youngster
350
00:46:54,903 --> 00:46:59,063
It may be learning how to grab a seal pup
before it risks a drive up the beach
351
00:47:09,523 --> 00:47:12,650
Whatever the reason the seal pup
- still alive
352
00:47:12,651 --> 00:47:16,812
- is tossed back and forth
for over half an hour
353
00:47:51,277 --> 00:47:55,438
Even when the pup is dead, the whales'
sport is not completely over
354
00:48:27,806 --> 00:48:31,967
We can only speculate at the real reasons
behind this extraordinary behaviour
355
00:48:46,598 --> 00:48:50,768
But for the whales, the hunting
season is a short one
356
00:48:50,769 --> 00:48:54,950
Before long the pups learn to
stay well clear of the water
357
00:48:54,951 --> 00:48:58,078
and the whales become less
and less successful
358
00:48:58,079 --> 00:49:02,249
After just two weeks, they move on
359
00:49:02,250 --> 00:49:06,422
The killing season is over
360
00:49:15,828 --> 00:49:17,912
That's how it often happens
along the coast
361
00:49:17,913 --> 00:49:21,041
Things are always changing
362
00:49:21,042 --> 00:49:24,169
They're never the same
for long in this,
363
00:49:24,170 --> 00:49:28,341
the most dynamic of all
the ocean's habitats
31678
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