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00:00:09,910 --> 00:00:11,080
The coast.

2
00:00:11,244 --> 00:00:14,284
The frontier
between land and sea.

3
00:00:17,183 --> 00:00:21,053
This is the most dynamic
of all the ocean habitats.

4
00:00:21,221 --> 00:00:24,061
The challenge here
is to survive change.

5
00:00:24,224 --> 00:00:26,294
Extreme change.

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00:00:53,653 --> 00:00:54,693
Cape Douglas,

7
00:00:54,854 --> 00:00:57,894
on the most westerly
of the Galapagos Islands,

8
00:00:58,058 --> 00:00:59,388
totally unprotected

9
00:00:59,559 --> 00:01:01,829
from the massive rollers
of the Pacific Ocean

10
00:01:01,995 --> 00:01:05,325
and one of the roughest
coastlines in the world.

11
00:01:40,967 --> 00:01:43,367
The marine iguanas
of the Galapagos

12
00:01:43,536 --> 00:01:46,206
are the world's only
seagoing lizards.

13
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Seaweed is all they eat.

14
00:01:56,916 --> 00:02:00,486
But doing so
is a dangerous business.

15
00:02:01,488 --> 00:02:04,458
The local crabs have become
specially flattened,

16
00:02:04,624 --> 00:02:07,294
minimizing the effect
of the pounding waves.

17
00:02:07,460 --> 00:02:11,600
And the iguanas have huge claws
to grip the rocks.

18
00:02:12,432 --> 00:02:15,302
This seaweed
really is fast food.

19
00:02:15,468 --> 00:02:18,668
There are only a few seconds
in which to grab a few mouthfuls

20
00:02:18,838 --> 00:02:22,138
before the next breaker
comes pounding in.

21
00:02:28,648 --> 00:02:32,788
Female iguanas feed
only on the exposed rocks,

22
00:02:32,952 --> 00:02:34,792
but the males, which are larger,

23
00:02:34,954 --> 00:02:39,124
swim and dive beneath
the surface to reach the weed.

24
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They go as deep as 10 meters.

25
00:02:43,663 --> 00:02:46,373
For there, beyond the
destructive reach of the waves,

26
00:02:46,533 --> 00:02:49,203
they find the best fronds.

27
00:02:49,369 --> 00:02:52,199
Being cold-blooded,
they have to return to land

28
00:02:52,372 --> 00:02:56,542
after about 10 minutes or so
to warm up again in the sun.

29
00:03:12,525 --> 00:03:15,155
Finding food
is not the only challenge

30
00:03:15,328 --> 00:03:16,528
for coastal residents.

31
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These rocky shores are hardly
a safe place to lay their eggs,

32
00:03:20,533 --> 00:03:24,103
and each year the marine iguanas
have to journey inland

33
00:03:24,270 --> 00:03:26,310
to find a more suitable one.

34
00:03:28,808 --> 00:03:31,408
The females lay their eggs
in burrows

35
00:03:31,578 --> 00:03:33,478
and leave them there to hatch.

36
00:03:33,646 --> 00:03:37,176
And to do that,
they need nice, soft sand.

37
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Down at the water's edge,

38
00:03:48,828 --> 00:03:51,928
it was easy to escape danger
in rocky crevices.

39
00:03:52,098 --> 00:03:55,928
But up here, the females
are dangerously exposed.

40
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A Galapagos hawk.

41
00:04:29,302 --> 00:04:32,472
The lizards don't give up
without a struggle.

42
00:04:52,959 --> 00:04:56,259
These hawks stay on the coast
all year,

43
00:04:56,429 --> 00:04:57,929
but they are exceptional.

44
00:04:58,097 --> 00:05:01,267
The majority of the birds
that frequent this frontier

45
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spend most of their time
elsewhere...

46
00:05:03,336 --> 00:05:05,396
in or above the open ocean.

47
00:05:05,572 --> 00:05:08,972
However, all sea birds
have to come to land

48
00:05:09,142 --> 00:05:10,812
in order to lay their eggs.

49
00:05:10,977 --> 00:05:13,107
And after spending
many lonely months

50
00:05:13,279 --> 00:05:14,909
searching the ocean for food,

51
00:05:15,081 --> 00:05:18,421
they have to re-establish
their social relationships.

52
00:05:20,653 --> 00:05:25,493
Frigate birds display
and exchange nesting material.

53
00:05:28,361 --> 00:05:30,931
Waved albatross dance.

54
00:05:42,642 --> 00:05:45,712
The need to lay their egg
on firm ground

55
00:05:45,878 --> 00:05:47,878
ties the albatross to the coast,

56
00:05:48,047 --> 00:05:50,547
but parental responsibilities
are shared.

57
00:05:50,717 --> 00:05:55,417
While one looks after the egg,
the other can go off to feed.

58
00:06:23,216 --> 00:06:24,216
The need to breed

59
00:06:24,384 --> 00:06:27,854
brings many different animals
to the coast each year

60
00:06:28,021 --> 00:06:29,691
for a few weeks.

61
00:06:29,856 --> 00:06:32,856
Male sea turtles
spend all their lives at sea.

62
00:06:33,026 --> 00:06:35,086
But the females, like birds,

63
00:06:35,261 --> 00:06:37,861
must come to land
to lay their eggs.

64
00:06:43,970 --> 00:06:45,300
To do that,

65
00:06:45,471 --> 00:06:49,141
green turtles that live and feed
off the coast of Brazil

66
00:06:49,309 --> 00:06:53,549
swim 1,500 miles
to the tiny island of Ascension

67
00:06:53,713 --> 00:06:57,523
that lies bang in the middle
of the Atlantic Ocean.

68
00:07:07,860 --> 00:07:11,100
Exactly how they manage
to navigate with such accuracy

69
00:07:11,264 --> 00:07:15,434
and find this tiny lump
of rock, just 7 miles wide,

70
00:07:15,601 --> 00:07:16,841
is a mystery.

71
00:07:19,572 --> 00:07:23,682
But each year, up to 5,000
turtles manage to do so.

72
00:07:23,843 --> 00:07:28,053
And then, close to the coast
of Ascension, they mate.

73
00:07:28,214 --> 00:07:31,624
Travelling to and from Ascension
and nesting here

74
00:07:31,784 --> 00:07:33,854
can take up to six months.

75
00:07:34,020 --> 00:07:38,590
And throughout that entire time,
none of them feed at all.

76
00:07:40,860 --> 00:07:44,260
After mating, a female has to
leave her natural element

77
00:07:44,430 --> 00:07:47,270
and haul herself up onto land.

78
00:07:47,433 --> 00:07:49,173
She does so at night,

79
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laying about three or four times
at around 15-day intervals.

80
00:07:53,639 --> 00:07:56,539
After that, she then swims
all the way back

81
00:07:56,709 --> 00:07:58,479
to the seas off Brazil.

82
00:07:58,644 --> 00:08:02,184
She returns to this very same
island throughout her life.

83
00:08:02,348 --> 00:08:06,418
Remarkably, all the world's sea
turtles return year after year

84
00:08:06,586 --> 00:08:10,016
to just a few traditional
breeding sites.

85
00:08:11,758 --> 00:08:15,088
Crab Island, in Australia,
is one of them.

86
00:08:17,363 --> 00:08:20,403
This tiny 2-mile-long
crescent of sand,

87
00:08:20,566 --> 00:08:23,536
lying a few miles off
Queensland's northerly tip,

88
00:08:23,703 --> 00:08:26,973
provides nesting sites
for half the entire population

89
00:08:27,140 --> 00:08:29,980
of one of the world's
rarest sea turtles.

90
00:08:30,143 --> 00:08:34,113
Flat back turtles are large...
over a meter long...

91
00:08:34,280 --> 00:08:35,680
but they have to be careful.

92
00:08:35,848 --> 00:08:38,248
There are other giant reptiles
here, too.

93
00:08:38,918 --> 00:08:41,018
Salt water crocodiles.

94
00:08:46,092 --> 00:08:48,662
Every night throughout the year,
there are flat backs

95
00:08:48,828 --> 00:08:52,828
burying their eggs all along
this lonely stretch of sand.

96
00:09:06,345 --> 00:09:10,945
Nine weeks later,
and things are about to happen.

97
00:09:16,122 --> 00:09:19,062
These eyes shining
in the darkness

98
00:09:19,225 --> 00:09:21,925
belong to night herons.

99
00:09:26,799 --> 00:09:28,469
As if from nowhere,

100
00:09:28,634 --> 00:09:32,204
hundreds of birds suddenly
appear on the sand dunes.

101
00:09:32,371 --> 00:09:34,871
Pelicans wait patiently.

102
00:09:35,641 --> 00:09:38,881
Jabiru storks pace up and down.

103
00:09:42,381 --> 00:09:46,491
Before long, they see
what they've been waiting for.

104
00:10:09,542 --> 00:10:13,042
Because these turtles lay
their eggs throughout the year,

105
00:10:13,212 --> 00:10:17,052
the hatchlings emerge night
after night in a steady trickle

106
00:10:17,216 --> 00:10:19,446
of beak-sized meals.

107
00:10:38,371 --> 00:10:40,441
Pelicans' broad beaks

108
00:10:40,606 --> 00:10:42,906
allow them to dig out
the hatchlings

109
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before the herons can spear them
on the surface.

110
00:10:51,017 --> 00:10:53,647
The surf may be hundreds
of meters away,

111
00:10:53,819 --> 00:10:56,489
and at least a third
of the tiny turtles

112
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do not survive the journey.

113
00:10:59,125 --> 00:11:01,855
And it's not just the birds
that take them.

114
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Crocodiles, sharks,
and hungry fish

115
00:11:08,234 --> 00:11:10,044
are all waiting in the shallows.

116
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In fact, only one
in every 100 hatchlings

117
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will survive to adulthood.

118
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Another beach,
another continent,

119
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and a very special night.

120
00:11:29,155 --> 00:11:31,815
Here in Costa Rica
there is a turtle

121
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which has found a way
of reducing these dangers.

122
00:11:35,127 --> 00:11:38,027
When Ridley's turtles arrive
to lay their eggs,

123
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they don't come in tens
or hundreds

124
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but in thousands.

125
00:11:43,369 --> 00:11:45,039
Over the next six days,

126
00:11:45,204 --> 00:11:49,374
around 400,000 females
will visit this beach.

127
00:11:51,177 --> 00:11:52,407
At the peak time,

128
00:11:52,578 --> 00:11:55,848
5,000 are coming and going
each hour.

129
00:11:56,015 --> 00:11:57,815
The beach gets so crowded

130
00:11:57,984 --> 00:11:59,654
that they have to clamber
over one another

131
00:11:59,819 --> 00:12:03,989
to find a bare patch of sand
where they can dig a nest hole.

132
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40 million eggs are laid
in these few days.

133
00:12:10,229 --> 00:12:12,629
So these turtles ensure
that, six weeks later,

134
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when their hatchlings emerge,
it's not just a trickle.

135
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It's a flood.

136
00:12:29,882 --> 00:12:32,822
On some nights,
over two million hatchlings

137
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race down to the sea together.

138
00:12:45,197 --> 00:12:47,527
With so many appearing
simultaneously,

139
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their predators are overwhelmed,

140
00:12:49,769 --> 00:12:54,239
and most of the young turtles
reach the sea safely.

141
00:13:06,218 --> 00:13:08,588
Leaving the sea
and emerging onto land

142
00:13:08,754 --> 00:13:10,294
is hard enough for turtles.

143
00:13:10,456 --> 00:13:13,456
It's even harder for fish.

144
00:13:20,499 --> 00:13:24,339
Each year, for hundreds of miles
along the Newfoundland coast,

145
00:13:24,503 --> 00:13:28,343
capelin throw themselves
onto the beaches.

146
00:13:53,733 --> 00:13:58,603
At least a million tons of fish
floundering out of the water.

147
00:13:58,771 --> 00:14:03,781
A real gift for scavenging
eagles and gulls.

148
00:14:22,328 --> 00:14:24,758
Odd though it may seem
for a fish,

149
00:14:24,930 --> 00:14:27,170
these capelin, like the turtles,

150
00:14:27,333 --> 00:14:30,673
have also come out of the sea
to breed.

151
00:14:41,614 --> 00:14:44,384
The males are trying to
fertilize the eggs

152
00:14:44,550 --> 00:14:47,420
that the females are depositing
in the sand.

153
00:14:47,586 --> 00:14:49,246
Like the Ridley's turtles,

154
00:14:49,421 --> 00:14:53,221
they have synchronized
their mass laying with the tide.

155
00:14:54,126 --> 00:14:56,996
In a few days, it will be over.

156
00:14:57,163 --> 00:14:59,203
Most of the capelin die

157
00:14:59,365 --> 00:15:03,735
but only after they've left
their eggs in the sand.

158
00:15:05,337 --> 00:15:08,407
Other capelin populations
lay their eggs in the ocean.

159
00:15:08,574 --> 00:15:11,944
So why do the Newfoundland fish
spawn on land?

160
00:15:12,111 --> 00:15:14,381
It seems that eggs deposited
in the beach

161
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may be safer from predators

162
00:15:16,315 --> 00:15:20,415
and develop faster than
in colder waters out to sea.

163
00:15:23,455 --> 00:15:25,255
But wherever they do so,

164
00:15:25,424 --> 00:15:28,934
the huge spawning shoals provide
the concentration of food

165
00:15:29,094 --> 00:15:33,064
that sea birds need
when they assemble to breed.

166
00:15:35,701 --> 00:15:39,541
95% of the world's sea birds
nest together,

167
00:15:39,705 --> 00:15:43,405
mostly in large,
spectacular colonies.

168
00:15:45,044 --> 00:15:47,114
This is Funk Island,

169
00:15:47,279 --> 00:15:50,009
40 miles off the coast
of Newfoundland,

170
00:15:50,182 --> 00:15:54,352
an isolated rock crammed
with breeding sea birds.

171
00:16:01,861 --> 00:16:04,561
This was the last
breeding ground

172
00:16:04,730 --> 00:16:08,370
for the flightless great auk,
sadly now extinct.

173
00:16:08,534 --> 00:16:12,404
Today it's still the world's
largest guillemot colony.

174
00:16:12,571 --> 00:16:15,171
Over a million of them share
the crowded island

175
00:16:15,341 --> 00:16:18,741
with 250,000 gannets.

176
00:16:19,979 --> 00:16:22,349
It's not for lack
of suitable sites

177
00:16:22,514 --> 00:16:25,854
that causes the sea birds
to breed in such densities.

178
00:16:26,018 --> 00:16:27,648
Here in the North Atlantic,

179
00:16:27,820 --> 00:16:30,020
there's a wide choice
of empty coastline

180
00:16:30,189 --> 00:16:31,919
that the birds could use.

181
00:16:32,091 --> 00:16:34,931
The key factor limiting
the size and location

182
00:16:35,094 --> 00:16:36,534
of sea bird colonies

183
00:16:36,695 --> 00:16:38,925
seems to be the availability
of food

184
00:16:39,098 --> 00:16:41,298
in the surrounding ocean.

185
00:16:45,337 --> 00:16:47,937
There are lots of hungry mouths
to feed

186
00:16:48,107 --> 00:16:50,937
and a constant demand for fish.

187
00:16:56,215 --> 00:16:59,515
Throughout the long summer days
at colonies like Funk,

188
00:16:59,685 --> 00:17:01,245
there's a continual stream

189
00:17:01,420 --> 00:17:04,520
of birds heading out
to the ocean to find food

190
00:17:04,690 --> 00:17:07,590
and returning with full crops
to feed their young.

191
00:17:16,602 --> 00:17:19,702
Gannets will travel
up to 200 miles from the colony

192
00:17:19,872 --> 00:17:22,612
on a single foraging trip.

193
00:17:22,775 --> 00:17:24,575
They're not fussy eaters

194
00:17:24,743 --> 00:17:28,413
and will take everything
from tiny sand eels to herring.

195
00:17:41,160 --> 00:17:42,490
Puffins, on the other hand,

196
00:17:42,661 --> 00:17:45,061
are very particular
about what they eat.

197
00:17:45,230 --> 00:17:47,770
And because they can only fly
short distances,

198
00:17:47,933 --> 00:17:49,873
they only nest
where there's a good supply

199
00:17:50,035 --> 00:17:52,695
of suitable food close by.

200
00:17:58,377 --> 00:18:01,347
One such place
is the Sea of Okhotsk

201
00:18:01,513 --> 00:18:04,183
in far eastern Russia.

202
00:18:05,951 --> 00:18:08,851
This is the island of Talan.

203
00:18:11,724 --> 00:18:15,594
Throughout the long Arctic
winter, it's encircled by ice.

204
00:18:15,761 --> 00:18:18,701
But as spring approaches,
that begins to break up,

205
00:18:18,864 --> 00:18:20,604
and sea birds that have spent
the winter

206
00:18:20,766 --> 00:18:23,596
feeding out on the open ocean
far to the south

207
00:18:23,769 --> 00:18:25,169
begin to return.

208
00:18:30,576 --> 00:18:33,746
Its isolated position
and steep cliffs

209
00:18:33,912 --> 00:18:36,952
make Talan a perfect
nesting site.

210
00:18:37,750 --> 00:18:40,720
The tufted puffins arrive first.

211
00:18:40,886 --> 00:18:42,146
These are the Pacific cousins

212
00:18:42,321 --> 00:18:46,021
of our less spectacular
Atlantic species.

213
00:18:49,461 --> 00:18:52,031
Horned puffins soon follow.

214
00:18:53,265 --> 00:18:57,595
In all, 14 different species
return to Talan each spring.

215
00:18:57,770 --> 00:19:01,240
And in just a few weeks,
the once-silent cliffs

216
00:19:01,407 --> 00:19:04,937
come alive to the calls
of 4 million breeding sea birds.

217
00:19:09,915 --> 00:19:13,075
This is a multi story avian city.

218
00:19:21,693 --> 00:19:24,163
Assembling
in these dense colonies

219
00:19:24,329 --> 00:19:27,269
after having spent
a largely solitary life at sea

220
00:19:27,433 --> 00:19:30,033
provides the birds
with the social stimulation

221
00:19:30,202 --> 00:19:33,372
that is the key to coordinating
their breeding.

222
00:19:34,873 --> 00:19:37,243
By nesting and laying together,

223
00:19:37,409 --> 00:19:39,079
they ensure that most
of their chicks

224
00:19:39,244 --> 00:19:42,414
will leave the nest
at exactly the same time.

225
00:19:42,581 --> 00:19:44,121
Just like the turtles,

226
00:19:44,283 --> 00:19:48,223
this is the way they spread
the impact of predators.

227
00:19:50,756 --> 00:19:52,716
The world's largest eagle.

228
00:19:52,891 --> 00:19:57,261
Steller's sea eagle, a third
as big again as a golden.

229
00:20:00,132 --> 00:20:01,372
Throughout the summer,

230
00:20:01,533 --> 00:20:05,273
the eagles hunt
in Talan's crowded colonies.

231
00:20:16,715 --> 00:20:18,945
Riding on the up drafts,

232
00:20:19,118 --> 00:20:20,688
they patrol
the top of the cliffs,

233
00:20:20,853 --> 00:20:23,793
looking out for any kittiwake
that ventures too far

234
00:20:23,956 --> 00:20:25,816
from the rock face.

235
00:20:30,863 --> 00:20:35,103
Suddenly, the huge eagle stoops
with the aerial agility

236
00:20:35,267 --> 00:20:36,327
of a falcon.

237
00:20:43,775 --> 00:20:46,235
Coordinated panic
among the kittiwakes

238
00:20:46,411 --> 00:20:47,981
confuses their attacker.

239
00:21:02,227 --> 00:21:05,157
But the eagle doesn't give up.

240
00:21:16,842 --> 00:21:19,342
And it has got one.

241
00:21:33,158 --> 00:21:37,598
Another kind of sea bird on Talan
has a particularly effective way

242
00:21:37,763 --> 00:21:39,863
of defending itself
against predators.

243
00:21:40,032 --> 00:21:43,632
But it doesn't appear
until an hour before sunset.

244
00:21:47,472 --> 00:21:51,012
As if from nowhere,
dense swarms of sea birds

245
00:21:51,176 --> 00:21:53,306
suddenly arrive offshore.

246
00:21:57,149 --> 00:21:59,779
They've spent the day
feeding far away,

247
00:21:59,952 --> 00:22:03,292
where the sea ice
has already broken up.

248
00:22:03,455 --> 00:22:07,525
They are crested auklets,
hardly bigger than starlings.

249
00:22:07,693 --> 00:22:10,263
A million of them return
to Talan each year

250
00:22:10,429 --> 00:22:13,129
to nest in its fields
of boulders.

251
00:22:19,338 --> 00:22:23,108
For the hour before sunset,
the hillsides come alive

252
00:22:23,275 --> 00:22:25,635
with huge flocks
of circling auklets.

253
00:22:25,811 --> 00:22:27,141
They're nervous.

254
00:22:27,312 --> 00:22:30,822
No one wants to be
the first to land.

255
00:22:36,088 --> 00:22:37,958
Auklets are very social

256
00:22:38,123 --> 00:22:40,093
when they are back together
at the coast.

257
00:22:40,259 --> 00:22:43,029
One of the advantages
of nesting in such densities

258
00:22:43,195 --> 00:22:45,425
may be the chance
to share information

259
00:22:45,597 --> 00:22:47,467
on good feeding sites.

260
00:22:47,633 --> 00:22:50,843
It also gives them
the opportunity to court.

261
00:22:55,007 --> 00:23:00,407
But perhaps most importantly,
there is safety in numbers.

262
00:23:04,716 --> 00:23:08,286
Ravens and peregrines circle
above the scree slope

263
00:23:08,453 --> 00:23:09,993
every evening.

264
00:23:24,736 --> 00:23:26,336
By taking off together,

265
00:23:26,505 --> 00:23:29,805
the auklets hope to confuse
the predators.

266
00:23:59,371 --> 00:24:03,141
Eventually,
their persistence pays off.

267
00:24:13,051 --> 00:24:15,621
The birds that face
the greatest challenge

268
00:24:15,787 --> 00:24:19,757
in coming to the coast to nest
are surely the penguins.

269
00:24:31,603 --> 00:24:33,103
Unable to fly,

270
00:24:33,271 --> 00:24:37,581
they have no alternative
but to brave the immense waves.

271
00:24:48,487 --> 00:24:50,757
Most penguins live
in the Southern Ocean,

272
00:24:50,922 --> 00:24:54,862
and they have to accept
being hurled about by the surf.

273
00:25:12,377 --> 00:25:14,877
Whatever the weather,
the penguin parents

274
00:25:15,046 --> 00:25:18,176
have to come back
to feed their chicks.

275
00:25:26,925 --> 00:25:29,525
A southern sea lion bull.

276
00:25:29,694 --> 00:25:30,964
He knows the penguins

277
00:25:31,129 --> 00:25:34,269
always use the same
traditional landing beach.

278
00:25:39,004 --> 00:25:40,774
Having braved
the thundering surf,

279
00:25:40,939 --> 00:25:43,839
the penguins have to make
a mad dash across open rock

280
00:25:44,009 --> 00:25:45,779
to get to their nests.

281
00:26:07,332 --> 00:26:10,902
Despite his massive size
and a body adapted for swimming,

282
00:26:11,069 --> 00:26:12,569
the bull chases the penguins

283
00:26:12,737 --> 00:26:16,607
for 40 or 50 meters
across the rocks.

284
00:27:08,326 --> 00:27:10,026
Having caught his penguin,

285
00:27:10,195 --> 00:27:13,125
the sea lion carries it out
into deeper water,

286
00:27:13,298 --> 00:27:16,198
where, by violently thrashing
the little body,

287
00:27:16,368 --> 00:27:18,838
he skins his meal.

288
00:27:26,578 --> 00:27:28,378
The seas around the Falklands

289
00:27:28,547 --> 00:27:31,017
are some of the roughest
in the world.

290
00:27:33,151 --> 00:27:34,791
In spite of that,

291
00:27:34,953 --> 00:27:36,523
the Southern Ocean
is home to millions

292
00:27:36,688 --> 00:27:39,718
of tiny sea birds hardly bigger
than swallows.

293
00:27:39,891 --> 00:27:40,991
Petrels.

294
00:27:41,159 --> 00:27:42,289
Being so small,

295
00:27:42,460 --> 00:27:44,500
they are very vulnerable
to the bad weather.

296
00:27:44,663 --> 00:27:47,773
A severe storm can blow them
miles off course

297
00:27:47,933 --> 00:27:51,103
and keep them away
from their nests for days.

298
00:27:51,269 --> 00:27:54,369
But these birds have developed
a very effective solution

299
00:27:54,539 --> 00:27:56,209
to that problem.

300
00:27:58,276 --> 00:28:00,836
They lay a rather special egg.

301
00:28:01,012 --> 00:28:04,452
Most birds' eggs, left exposed
for even a few hours,

302
00:28:04,616 --> 00:28:06,576
will chill and never hatch.

303
00:28:06,751 --> 00:28:08,721
But these eggs are different.

304
00:28:08,887 --> 00:28:12,117
They can be left for several
days without incubation

305
00:28:12,290 --> 00:28:13,560
and remain undamaged

306
00:28:13,725 --> 00:28:17,055
while the parents
struggle home through the storm.

307
00:28:18,930 --> 00:28:22,200
Prions have also come up
with a good way

308
00:28:22,367 --> 00:28:25,067
to avoid most predators.

309
00:28:25,637 --> 00:28:29,737
They never come back
to the coast until after dark.

310
00:28:31,276 --> 00:28:34,076
These are thin-billed prions.

311
00:28:34,713 --> 00:28:37,653
Their burrows honeycomb
this hillside in the Falklands.

312
00:28:37,816 --> 00:28:40,546
It's deserted throughout
the daylight hours.

313
00:28:40,719 --> 00:28:41,919
But as soon as it's dark

314
00:28:42,087 --> 00:28:44,687
and difficult
for airborne predators to hunt,

315
00:28:44,856 --> 00:28:46,816
the prions return.

316
00:28:54,099 --> 00:28:56,899
As soon as they land, they call.

317
00:29:02,040 --> 00:29:03,370
The problem, of course,

318
00:29:03,541 --> 00:29:06,711
is finding your burrow
among all the others.

319
00:29:07,946 --> 00:29:10,746
He's listening out
for his mate's call.

320
00:29:12,817 --> 00:29:14,547
And down he goes.

321
00:29:21,393 --> 00:29:23,633
The Alaskan coast.

322
00:29:23,795 --> 00:29:28,265
It's spring, and the last of
the winter storms is subsiding.

323
00:29:29,901 --> 00:29:32,401
The plankton in this sea
is in bloom again.

324
00:29:32,570 --> 00:29:37,340
And just offshore, humpback
whales have returned to feed.

325
00:29:43,314 --> 00:29:45,284
For these huge animals,

326
00:29:45,450 --> 00:29:48,220
there's a real risk of coming
into such shallow water.

327
00:29:48,386 --> 00:29:52,256
And each year a good number
of them pay the price.

328
00:29:57,295 --> 00:30:00,355
It's an ignominious ending
for an ageing whale.

329
00:30:00,532 --> 00:30:04,502
But so much flesh
will not go to waste.

330
00:30:05,637 --> 00:30:09,467
A black bear emerges cautiously
from the woods.

331
00:30:18,249 --> 00:30:21,419
Visitors to the coast
that don't come to breed

332
00:30:21,586 --> 00:30:23,616
have usually come to scavenge.

333
00:30:23,788 --> 00:30:25,718
A whole range
of different animals

334
00:30:25,890 --> 00:30:29,160
have learned to exploit
the enormous quantity of food

335
00:30:29,327 --> 00:30:33,057
that washes up every day
on coastlines around the world.

336
00:30:34,699 --> 00:30:36,969
But like so much at the coast,

337
00:30:37,135 --> 00:30:40,435
the quantity of flotsam
and jetsam is unpredictable.

338
00:30:40,605 --> 00:30:43,865
Nobody can rely on it alone.

339
00:30:47,212 --> 00:30:50,952
This carcass even attracted
a shy pack of wolves

340
00:30:51,116 --> 00:30:53,346
only too happy
to anoint themselves

341
00:30:53,518 --> 00:30:55,448
with the scent of rotting whale.

342
00:31:00,425 --> 00:31:01,655
It was months

343
00:31:01,826 --> 00:31:04,926
before the scavengers
finally cleaned up all the meat

344
00:31:05,096 --> 00:31:09,126
on this huge and unpredictable
gift from the sea.

345
00:31:14,072 --> 00:31:17,042
Whales give birth
to their young at sea

346
00:31:17,208 --> 00:31:20,078
and so can spend
their entire lives there.

347
00:31:20,245 --> 00:31:21,905
Other marine mammals,

348
00:31:22,080 --> 00:31:24,550
ones that are in fact
distant cousins of bears,

349
00:31:24,716 --> 00:31:28,986
have to return each year
to their ancestral home on land.

350
00:31:34,292 --> 00:31:35,162
The high Arctic.

351
00:31:35,326 --> 00:31:38,326
Here lives one of them...
the walrus.

352
00:31:47,639 --> 00:31:51,409
Walruses spend
nearly all their lives at sea.

353
00:31:51,576 --> 00:31:53,576
But each year
for just a few weeks,

354
00:31:53,745 --> 00:31:56,245
they have to return
to the coast.

355
00:31:57,949 --> 00:31:59,949
They seek out isolated beaches,

356
00:32:00,118 --> 00:32:04,188
like this one on Round Island
in the far northern Pacific.

357
00:32:04,355 --> 00:32:07,585
Suitable sites like this,
free from bears,

358
00:32:07,759 --> 00:32:11,699
are so scarce that at times
as many as 14,000 animals

359
00:32:11,863 --> 00:32:14,633
will cram themselves
onto this one beach.

360
00:32:23,608 --> 00:32:26,738
When they first emerge from
the sea, the walrus are white.

361
00:32:26,911 --> 00:32:27,781
That's because,

362
00:32:27,946 --> 00:32:31,106
being warm-blooded animals
living in a very cold ocean,

363
00:32:31,282 --> 00:32:33,852
they conserve heat
by keeping their blood

364
00:32:34,018 --> 00:32:36,988
concentrated in the core
of their bodies.

365
00:32:37,155 --> 00:32:39,185
On land, it's warm enough

366
00:32:39,357 --> 00:32:42,427
for them to allow their outer
blood vessels to dilate,

367
00:32:42,594 --> 00:32:46,604
and that turns their skin
from white to pink.

368
00:32:54,239 --> 00:32:57,669
Now they can moult
the outer layers of their skin,

369
00:32:57,842 --> 00:33:00,942
rubbing themselves
up against the rocks.

370
00:33:04,148 --> 00:33:05,778
But more than anything else,

371
00:33:05,950 --> 00:33:08,350
coming to land
brings the walrus relief

372
00:33:08,519 --> 00:33:09,599
from having to spend energy

373
00:33:09,721 --> 00:33:11,791
maintaining
their body temperature

374
00:33:11,956 --> 00:33:13,986
in an icy-cold ocean.

375
00:33:16,995 --> 00:33:21,055
Heat conservation, in fact,
may well be the primary reason

376
00:33:21,232 --> 00:33:26,272
so many sea mammals are forced
to return to the land each year.

377
00:33:30,808 --> 00:33:35,008
The world's coldest seas
are in Antarctica.

378
00:33:35,179 --> 00:33:38,719
Each spring, half the world's
southern elephant seals return

379
00:33:38,883 --> 00:33:41,323
to the island of South Georgia.

380
00:33:42,587 --> 00:33:45,587
Elephant seals have
particularly thick insulation

381
00:33:45,757 --> 00:33:47,487
of blubber that keeps them warm.

382
00:33:47,659 --> 00:33:52,029
For them, breeding is the only
reason to leave the sea.

383
00:33:57,035 --> 00:34:01,405
With temperatures down to -20
and 100-mile-an-hour winds,

384
00:34:01,572 --> 00:34:03,872
it can't be comfortable
out on the beach.

385
00:34:04,042 --> 00:34:08,052
But heat dissipates more rapidly
through water than through air.

386
00:34:08,212 --> 00:34:10,882
So even in these conditions,
their young,

387
00:34:11,049 --> 00:34:13,119
which at first don't have
a thick coat of blubber,

388
00:34:13,284 --> 00:34:16,354
will be far warmer on the land.

389
00:34:17,255 --> 00:34:19,755
Once the males are established
on the beach,

390
00:34:19,924 --> 00:34:21,694
the females soon follow.

391
00:34:26,097 --> 00:34:28,397
Within just 10 days,

392
00:34:28,566 --> 00:34:33,566
the empty beach fills up
with 6,000 elephant seals.

393
00:34:34,372 --> 00:34:35,742
Almost immediately,

394
00:34:35,907 --> 00:34:39,737
the females give birth to pups
sired the previous year.

395
00:34:49,520 --> 00:34:51,220
Their milk is very rich,

396
00:34:51,389 --> 00:34:54,319
and the pups grow
astonishingly quickly.

397
00:35:01,632 --> 00:35:05,642
In just three weeks,
they turn from thin bags of skin

398
00:35:05,803 --> 00:35:08,773
to fat balls of blubber.

399
00:35:08,940 --> 00:35:10,810
As soon as they've given birth,

400
00:35:10,975 --> 00:35:13,735
the females become
sexually receptive again.

401
00:35:13,911 --> 00:35:16,511
And it's now
that the advantages of breeding

402
00:35:16,681 --> 00:35:19,121
in such dense colonies
become clear.

403
00:35:19,283 --> 00:35:22,093
Females can make their choice
from many males,

404
00:35:22,253 --> 00:35:27,663
while successful males can have
access to lots of females.

405
00:35:32,463 --> 00:35:36,733
But to gain that access
and control a harem of females,

406
00:35:36,901 --> 00:35:40,041
a bull must be prepared
to fight.

407
00:36:00,725 --> 00:36:03,555
The larger the male,
the louder the roar

408
00:36:03,728 --> 00:36:05,998
and the more likely he is
to win.

409
00:36:15,406 --> 00:36:17,506
When males are well matched,

410
00:36:17,675 --> 00:36:22,045
these bloody battles will last
20 minutes or more.

411
00:36:40,064 --> 00:36:43,574
Eventually, the loser retreats
into a stream,

412
00:36:43,734 --> 00:36:46,304
already pink with his own blood.

413
00:36:57,281 --> 00:36:59,851
These battles
certainly help females select

414
00:37:00,017 --> 00:37:01,247
the strongest bulls,

415
00:37:01,419 --> 00:37:03,989
but they bring great dangers
for the pups.

416
00:37:14,699 --> 00:37:17,129
Each year, in the denser parts
of the colony,

417
00:37:17,301 --> 00:37:20,771
a fifth of the pups
are crushed to death.

418
00:37:20,938 --> 00:37:22,768
This is why
it may be better to mate

419
00:37:22,940 --> 00:37:26,480
at the edge of the beach,
close to the sea.

420
00:37:31,849 --> 00:37:34,549
Less dominant males hide
in the surf.

421
00:37:34,719 --> 00:37:36,589
They're waiting to try and steal

422
00:37:36,754 --> 00:37:40,594
an illicit mating with females
as they come and go.

423
00:37:44,262 --> 00:37:47,562
This male knows that he's been
spotted by the big bull

424
00:37:47,732 --> 00:37:51,372
who claims all the females
on this part of the beach.

425
00:38:53,864 --> 00:38:57,174
Breeding in groups
can bring advantages to pups

426
00:38:57,335 --> 00:38:59,465
as well as to adults.

427
00:39:05,243 --> 00:39:07,313
Along the coast of Patagonia,

428
00:39:07,478 --> 00:39:09,908
southern sea lions breed
together each year

429
00:39:10,081 --> 00:39:12,551
in groups
several hundred strong.

430
00:39:13,618 --> 00:39:15,088
For the growing pups,

431
00:39:15,253 --> 00:39:17,623
these colonies act
rather like a school.

432
00:39:17,788 --> 00:39:21,018
The bonds and relationships
developed here on the beach

433
00:39:21,192 --> 00:39:23,492
may be vital
for the rest of their lives.

434
00:39:23,661 --> 00:39:25,861
Sea lions are very social
animals.

435
00:39:26,030 --> 00:39:28,430
And as adults and young
forage together,

436
00:39:28,599 --> 00:39:30,299
they probably share information

437
00:39:30,468 --> 00:39:33,298
about the location
of good feeding sites.

438
00:39:35,940 --> 00:39:37,770
Conditions here
could hardly be better

439
00:39:37,942 --> 00:39:39,782
for the growing youngsters.

440
00:39:40,911 --> 00:39:42,081
As the tide goes out,

441
00:39:42,246 --> 00:39:45,376
it leaves behind
a selection of sheltered pools.

442
00:39:46,584 --> 00:39:49,654
Perfect places
for learning to swim.

443
00:40:23,988 --> 00:40:26,458
At high tide,
it's easy for the pups

444
00:40:26,624 --> 00:40:30,494
to take their first,
experimental dips in the surf.

445
00:41:03,728 --> 00:41:06,228
A killer whale.

446
00:41:07,865 --> 00:41:11,935
These young pups have never seen
anything like it before.

447
00:41:23,647 --> 00:41:26,747
The whales, though,
are very experienced.

448
00:41:26,917 --> 00:41:29,917
Each year, this same group
turns up along the coast

449
00:41:30,087 --> 00:41:33,957
at precisely the same time as
the pups are starting to swim.

450
00:41:44,235 --> 00:41:46,535
The whales need to surprise
the pups,

451
00:41:46,704 --> 00:41:50,544
so they've stopped calling
to one another and keep silent.

452
00:41:58,849 --> 00:42:01,079
Speed is everything.

453
00:42:04,588 --> 00:42:07,588
The whales do not take pups
that are out of the water,

454
00:42:07,758 --> 00:42:10,788
but sometimes their momentum
drives them right up the beach.

455
00:42:10,961 --> 00:42:14,061
And then there's real danger
of getting stuck.

456
00:43:47,925 --> 00:43:51,125
The whale has to thrash
in this frenzied way

457
00:43:51,295 --> 00:43:52,855
to get off the beach.

458
00:43:53,030 --> 00:43:55,530
Most of the pups are taken
into deep water

459
00:43:55,699 --> 00:43:56,739
while they're still alive.

460
00:43:56,800 --> 00:44:00,670
And there the whales
apparently play with them.

461
00:44:24,395 --> 00:44:28,495
Often an adult whale is joined
in the game by a youngster.

462
00:44:28,666 --> 00:44:31,326
It may be learning
how to grab a seal pup

463
00:44:31,502 --> 00:44:34,172
before it risks
a drive up the beach.

464
00:44:41,912 --> 00:44:45,622
Whatever the reason,
the seal pup, still alive,

465
00:44:45,783 --> 00:44:49,823
is tossed back and forth
for over half an hour.

466
00:45:22,219 --> 00:45:24,119
Even when the pup is dead,

467
00:45:24,288 --> 00:45:26,858
the whales' sport
is not completely over.

468
00:45:56,353 --> 00:45:59,223
We can only speculate
at the real reasons

469
00:45:59,390 --> 00:46:02,760
behind this extraordinary
behaviour.

470
00:46:15,506 --> 00:46:19,636
But for the whales, the hunting
season is a short one.

471
00:46:19,810 --> 00:46:23,210
Before long, the pups learn
to stay well clear of the water,

472
00:46:23,380 --> 00:46:26,580
and the whales become
less and less successful.

473
00:46:26,750 --> 00:46:29,920
After just two weeks,
they move on.

474
00:46:30,621 --> 00:46:33,621
The killing season is over.

475
00:46:42,700 --> 00:46:45,700
That's how it often happens
along the coast.

476
00:46:45,869 --> 00:46:48,339
Things are always changing.

477
00:46:48,505 --> 00:46:51,535
They're never the same for long
in this,

478
00:46:51,709 --> 00:46:55,749
the most dynamic
of all the ocean's habitats.