1
00:00:06,006 --> 00:00:07,465
[theme tune playing]

2
00:00:19,394 --> 00:00:21,646
[David Attenborough]
Sixty thousand years ago,

3
00:00:22,147 --> 00:00:25,608
humans left Africa for the first time.

4
00:00:30,697 --> 00:00:33,408
Since then, we haven't stopped,

5
00:00:34,325 --> 00:00:37,162
traveling to every corner of the Earth.

6
00:00:40,040 --> 00:00:43,543
But our journey is just one of many.

7
00:00:44,711 --> 00:00:46,296
At any given moment,

8
00:00:47,213 --> 00:00:50,467
billions of animals are on the move.

9
00:00:50,550 --> 00:00:52,302
[music becomes stirring]

10
00:00:54,220 --> 00:00:57,932
And the health of our planet
depends on it.

11
00:00:59,267 --> 00:01:00,351
[music abates]

12
00:01:09,402 --> 00:01:11,571
[music fades, intensifies]

13
00:01:18,703 --> 00:01:23,666
Migration is the most vital
survival strategy.

14
00:01:23,750 --> 00:01:25,210
[music intensifies]

15
00:01:28,338 --> 00:01:29,589
Whether to feed…

16
00:01:32,175 --> 00:01:33,176
to breed…

17
00:01:33,968 --> 00:01:34,844
[elephants roar]

18
00:01:34,928 --> 00:01:36,471
…or to find a new home.

19
00:01:43,561 --> 00:01:46,022
And it's not without risk.

20
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[music intensifies]

21
00:01:50,777 --> 00:01:53,113
-[growls]
-[screeches]

22
00:01:53,905 --> 00:01:55,031
[trills]

23
00:01:55,115 --> 00:01:58,952
This series traces extraordinary journeys

24
00:01:59,035 --> 00:02:03,039
in a world that is changing
faster than ever.

25
00:02:03,123 --> 00:02:04,874
[rousing music playing]

26
00:02:07,460 --> 00:02:11,047
And only now
are we beginning to understand

27
00:02:12,132 --> 00:02:14,050
that all life on Earth

28
00:02:15,552 --> 00:02:19,055
depends on the freedom to move.

29
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[music intensifies]

30
00:02:27,981 --> 00:02:28,815
[music ends]

31
00:02:32,026 --> 00:02:33,236
[somber music fades in]

32
00:02:33,319 --> 00:02:34,362
[wind howling]

33
00:02:45,165 --> 00:02:49,502
Every year, this land in Botswana
is transformed.

34
00:02:52,463 --> 00:02:56,885
These scars are the only sign
that it was covered by water

35
00:02:56,968 --> 00:02:58,678
just three months ago.

36
00:02:59,179 --> 00:03:01,014
[poignant music playing]

37
00:03:03,766 --> 00:03:06,019
Then, rich and green.

38
00:03:07,937 --> 00:03:10,773
Now, baked and barren.

39
00:03:19,949 --> 00:03:24,287
This change drives animals
to move en masse.

40
00:03:24,370 --> 00:03:25,580
[bellowing]

41
00:03:27,749 --> 00:03:30,001
[dramatic tribal music playing]

42
00:03:39,427 --> 00:03:43,723
Cape buffalo are marching
across the Kalahari Desert

43
00:03:43,806 --> 00:03:46,517
towards the last remaining water.

44
00:03:54,192 --> 00:03:58,571
Groups have come together
and formed a mega herd.

45
00:04:00,031 --> 00:04:01,074
[grunting]

46
00:04:09,249 --> 00:04:11,084
The largest in Africa.

47
00:04:13,753 --> 00:04:15,004
[music continues]

48
00:04:20,176 --> 00:04:21,552
[music abates]

49
00:04:21,636 --> 00:04:25,390
All are making the same annual pilgrimage

50
00:04:26,432 --> 00:04:28,977
to one remote marsh.

51
00:04:31,521 --> 00:04:33,022
[chirping]

52
00:04:35,942 --> 00:04:39,195
And others are relying on them to do so.

53
00:04:42,949 --> 00:04:46,536
These lions are buffalo specialists.

54
00:04:53,084 --> 00:04:55,336
And the mega herd's arrival

55
00:04:55,420 --> 00:04:58,589
is the most important event of their year.

56
00:05:02,093 --> 00:05:06,306
For weeks, they've been waiting
for the buffalo army.

57
00:05:09,642 --> 00:05:13,646
Eyes fixed on every shape
crossing the horizon.

58
00:05:13,730 --> 00:05:15,565
[menacing music playing]

59
00:05:22,280 --> 00:05:23,948
[buffalo calls]

60
00:05:25,325 --> 00:05:26,409
[growls softly]

61
00:05:26,492 --> 00:05:29,078
[birds shrieking]

62
00:05:29,162 --> 00:05:30,538
[insects buzzing]

63
00:05:33,458 --> 00:05:35,543
[growls softly]

64
00:05:35,626 --> 00:05:36,878
Finally.

65
00:05:38,838 --> 00:05:40,673
[dramatic music playing]

66
00:05:49,349 --> 00:05:50,391
[music abates]

67
00:05:50,475 --> 00:05:52,352
[rasping, snorting]

68
00:05:52,435 --> 00:05:56,981
The approaching horde
is a wall of horns and muscle.

69
00:06:10,411 --> 00:06:13,373
But the lions must find a weakness.

70
00:06:31,224 --> 00:06:32,975
And this could be it.

71
00:06:34,018 --> 00:06:35,520
A lone bull.

72
00:06:37,313 --> 00:06:39,565
He may be separate from the herd,

73
00:06:39,649 --> 00:06:42,735
but he is four times heavier than a lion

74
00:06:43,319 --> 00:06:46,614
and one of Africa's
most dangerous animals.

75
00:06:49,075 --> 00:06:51,702
The pride must approach with care.

76
00:06:57,834 --> 00:06:59,210
[buffalo snorting]

77
00:07:01,295 --> 00:07:06,092
One by one, they casually walk towards him

78
00:07:06,175 --> 00:07:08,761
as if uninterested in a hunt.

79
00:07:20,815 --> 00:07:24,110
In fact, they're falling into position.

80
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[menacing music playing]

81
00:07:39,083 --> 00:07:41,085
-[lion growls]
-[buffalo snorts]

82
00:07:44,380 --> 00:07:46,382
[buffalo snorting]

83
00:07:49,552 --> 00:07:51,012
[music intensifies]

84
00:07:55,808 --> 00:07:56,726
[lion roars]

85
00:08:13,409 --> 00:08:16,412
The females take it in turns to attack…

86
00:08:22,084 --> 00:08:23,544
tiring the bull.

87
00:08:25,796 --> 00:08:27,798
[dramatic tribal music playing]

88
00:08:34,722 --> 00:08:37,934
Now, the heavier males join the fight.

89
00:08:38,017 --> 00:08:39,310
[music intensifies]

90
00:08:42,522 --> 00:08:43,731
[buffalo bellows]

91
00:08:48,945 --> 00:08:50,321
[lions snarl]

92
00:08:57,745 --> 00:08:59,539
[buffalo groans]

93
00:09:04,585 --> 00:09:05,628
[music abates]

94
00:09:07,171 --> 00:09:08,631
[buffalo bellowing]

95
00:09:11,759 --> 00:09:12,969
[bellowing fades]

96
00:09:13,052 --> 00:09:16,180
The pride has honed
their technique so well

97
00:09:16,931 --> 00:09:18,724
that in just three minutes,

98
00:09:19,934 --> 00:09:23,604
they have defeated
their most formidable opponent.

99
00:09:23,688 --> 00:09:25,356
[stillness]

100
00:09:32,154 --> 00:09:33,531
[music fades away]

101
00:09:33,614 --> 00:09:36,409
The migration on which the lions depend

102
00:09:36,492 --> 00:09:39,704
is one of millions driven by the seasons.

103
00:09:40,830 --> 00:09:42,540
And they, in turn,

104
00:09:43,165 --> 00:09:45,585
are a consequence of another journey.

105
00:09:45,668 --> 00:09:46,502
[music reprises]

106
00:09:46,586 --> 00:09:50,298
Our planet's year-long loop
around the sun.

107
00:09:54,093 --> 00:09:55,386
As it travels,

108
00:09:55,469 --> 00:10:00,474
it does so on a tilt
of 23 and a half degrees.

109
00:10:03,728 --> 00:10:06,772
And it is this that creates our seasons.

110
00:10:06,856 --> 00:10:08,274
[music intensifies]

111
00:10:09,650 --> 00:10:14,030
To understand how,
keep your eye on the North Pole.

112
00:10:16,490 --> 00:10:19,994
For half the year,
it's angled away from the sun,

113
00:10:20,578 --> 00:10:23,039
bringing darkness and winter.

114
00:10:23,122 --> 00:10:24,081
[music soars]

115
00:10:28,085 --> 00:10:31,964
For the other half,
it swings towards the sun,

116
00:10:32,757 --> 00:10:34,717
bringing longer days.

117
00:10:42,975 --> 00:10:45,311
It's this annual cycle

118
00:10:45,394 --> 00:10:48,898
that drives the greatest movements
of life on Earth.

119
00:10:51,734 --> 00:10:56,864
And in the Northern Hemisphere,
this brings the year's biggest change.

120
00:10:59,533 --> 00:11:00,576
Spring.

121
00:11:07,750 --> 00:11:09,460
[music fades out, ends]

122
00:11:11,045 --> 00:11:15,841
In late March, the days lengthen faster
than at any other time.

123
00:11:18,052 --> 00:11:20,054
[poignant string music playing]

124
00:11:20,554 --> 00:11:24,350
Sunlight increases,
quickly heating the land.

125
00:11:25,017 --> 00:11:26,018
[thunder rumbles]

126
00:11:26,102 --> 00:11:27,812
Triggering rainstorms.

127
00:11:30,064 --> 00:11:33,150
The Northern Hemisphere
suddenly becomes warmer

128
00:11:34,360 --> 00:11:35,361
and wetter.

129
00:11:37,780 --> 00:11:39,281
Perfect for plants.

130
00:11:40,658 --> 00:11:42,034
[music intensifies]

131
00:11:47,832 --> 00:11:50,459
The land turns green.

132
00:11:54,046 --> 00:11:55,423
[music fades away]

133
00:11:55,506 --> 00:12:01,303
And one animal exploits the boom
in plant growth like no other.

134
00:12:01,804 --> 00:12:03,222
-[chirping]
-[tiny footsteps]

135
00:12:08,811 --> 00:12:10,229
A week ago,

136
00:12:10,312 --> 00:12:12,606
this desert locust in Ethiopia

137
00:12:13,315 --> 00:12:17,278
was a shy, solitary creature
that moved very little.

138
00:12:20,239 --> 00:12:21,741
[dark playful music playing]

139
00:12:21,824 --> 00:12:23,451
Not anymore.

140
00:12:30,166 --> 00:12:32,710
When available food skyrockets,

141
00:12:33,419 --> 00:12:36,672
locusts switch to swarm mode.

142
00:12:37,757 --> 00:12:39,175
[music intensifies]

143
00:12:39,258 --> 00:12:40,301
[chorus of chirping]

144
00:12:40,384 --> 00:12:41,927
They start marching

145
00:12:42,678 --> 00:12:45,306
and multiply ten times faster.

146
00:12:45,806 --> 00:12:48,100
[strident string music playing]

147
00:12:54,148 --> 00:12:55,900
As their numbers explode,

148
00:12:55,983 --> 00:12:58,194
they strip the land bare.

149
00:13:02,448 --> 00:13:05,409
So to find more and more food,

150
00:13:05,493 --> 00:13:08,245
they must keep moving.

151
00:13:09,663 --> 00:13:11,081
[music intensifies]

152
00:13:26,514 --> 00:13:28,307
The swarm grows.

153
00:13:32,728 --> 00:13:34,230
And grows.

154
00:13:34,772 --> 00:13:36,190
[music intensifies]

155
00:13:38,651 --> 00:13:41,862
Devouring every plant in its path.

156
00:13:45,157 --> 00:13:47,159
But this is just the start.

157
00:13:49,036 --> 00:13:52,289
On foot, they can only move so far.

158
00:13:52,915 --> 00:13:53,999
[music ends abruptly]

159
00:13:55,376 --> 00:13:56,502
To go further,

160
00:13:58,087 --> 00:14:00,256
they must change form.

161
00:14:01,048 --> 00:14:02,341
[soft squelching]

162
00:14:12,226 --> 00:14:14,228
They grow wings.

163
00:14:17,523 --> 00:14:19,108
[suspenseful music playing]

164
00:14:22,653 --> 00:14:24,572
[music becomes uplifting]

165
00:14:36,166 --> 00:14:39,086
Now, with an even larger appetite,

166
00:14:39,670 --> 00:14:42,756
the entire army takes to the sky.

167
00:14:45,634 --> 00:14:47,469
[music becomes dramatic]

168
00:14:51,974 --> 00:14:52,850
They eat…

169
00:14:54,852 --> 00:14:56,020
and fly.

170
00:15:01,942 --> 00:15:02,902
Eat…

171
00:15:04,945 --> 00:15:05,988
and fly.

172
00:15:06,071 --> 00:15:07,615
[cacophonous buzzing]

173
00:15:13,996 --> 00:15:17,207
They come together to form a super swarm,

174
00:15:18,375 --> 00:15:20,794
200 billion strong.

175
00:15:23,005 --> 00:15:26,175
The biggest seen in 70 years.

176
00:15:30,471 --> 00:15:34,516
It consumes 400,000 tons of food

177
00:15:34,600 --> 00:15:36,435
every single day.

178
00:15:40,648 --> 00:15:43,609
So if the whole swarm is to feed,

179
00:15:43,692 --> 00:15:46,612
it must move further and faster.

180
00:15:46,695 --> 00:15:48,155
[music intensifies]

181
00:15:54,954 --> 00:15:57,581
It travels 100 kilometers a day

182
00:15:57,665 --> 00:16:00,292
across farmland and towns.

183
00:16:09,551 --> 00:16:10,886
[music abates]

184
00:16:10,970 --> 00:16:13,973
It sweeps across country after country…

185
00:16:16,350 --> 00:16:18,394
and most astonishing of all,

186
00:16:18,477 --> 00:16:20,896
it even crosses the Red Sea.

187
00:16:27,152 --> 00:16:32,741
It's the first time a swarm clears
the Himalayas and reaches Tibet.

188
00:16:34,493 --> 00:16:35,869
[music intensifies]

189
00:16:37,871 --> 00:16:39,498
Everywhere it goes,

190
00:16:41,375 --> 00:16:42,960
it brings chaos.

191
00:16:54,346 --> 00:16:58,976
It will keep moving
until the changing seasons bring drought.

192
00:17:01,311 --> 00:17:04,023
For when their food finally disappears…

193
00:17:06,817 --> 00:17:08,235
so will they.

194
00:17:09,319 --> 00:17:11,196
[music fades out abruptly]

195
00:17:14,575 --> 00:17:16,618
[solemn drumbeat reverberates]

196
00:17:16,702 --> 00:17:18,996
[metallic percussive sound reverberates]

197
00:17:19,496 --> 00:17:24,293
In April, day length in the North
continues to rise.

198
00:17:24,376 --> 00:17:26,628
[subdued expectant music playing

199
00:17:26,712 --> 00:17:30,799
The increase in sunlight warms the oceans,

200
00:17:30,883 --> 00:17:33,594
creating vast algal blooms

201
00:17:33,677 --> 00:17:36,180
and a sudden abundance of food.

202
00:17:39,600 --> 00:17:42,728
For one animal,
this is the moment to travel.

203
00:17:45,230 --> 00:17:48,192
[music becomes suspenseful]

204
00:17:51,653 --> 00:17:55,908
Midnight on a remote island
off British Columbia.

205
00:17:59,328 --> 00:18:00,370
Underground…

206
00:18:02,456 --> 00:18:04,041
something stirs.

207
00:18:08,253 --> 00:18:09,963
[whimsical music playing]

208
00:18:10,464 --> 00:18:11,423
[chirruping]

209
00:18:11,507 --> 00:18:15,886
This ancient murrelet chick
has only just hatched,

210
00:18:17,805 --> 00:18:22,101
yet it's about to face
the toughest journey it will ever make.

211
00:18:25,729 --> 00:18:27,731
She hasn't had her first meal

212
00:18:28,607 --> 00:18:30,609
and urgently needs food.

213
00:18:31,193 --> 00:18:34,113
[warbling]

214
00:18:34,196 --> 00:18:35,823
Mum makes contact.

215
00:18:35,906 --> 00:18:36,865
[chick chirruping]

216
00:18:38,450 --> 00:18:39,910
[warbling]

217
00:18:40,619 --> 00:18:44,331
Across the island,
hungry chicks emerge from their burrows

218
00:18:46,041 --> 00:18:48,210
following their parents' calls.

219
00:18:50,587 --> 00:18:53,340
But if they're expecting to eat now,

220
00:18:54,341 --> 00:18:56,301
they're going to be disappointed.

221
00:18:57,427 --> 00:18:59,346
[music intensifies]

222
00:19:02,141 --> 00:19:04,393
This is the only seabird

223
00:19:04,935 --> 00:19:07,938
that is fed exclusively at sea.

224
00:19:08,021 --> 00:19:09,148
[music abates]

225
00:19:10,232 --> 00:19:13,026
The chicks just need to get there.

226
00:19:13,110 --> 00:19:15,279
[peeping]

227
00:19:15,362 --> 00:19:17,197
They can't yet fly,

228
00:19:17,781 --> 00:19:19,867
so their only way to the ocean

229
00:19:20,784 --> 00:19:21,952
is on foot.

230
00:19:22,035 --> 00:19:24,329
-[quirky dramatic music playing]
-[peeping]

231
00:19:25,873 --> 00:19:27,749
[chicks peeping]

232
00:19:29,585 --> 00:19:33,589
While waiting till nightfall makes sense
to avoid predators,

233
00:19:34,381 --> 00:19:37,634
it's a little harder to see
where you're going.

234
00:19:37,718 --> 00:19:38,719
[squeaks]

235
00:19:39,386 --> 00:19:40,220
[soft thud]

236
00:19:45,267 --> 00:19:48,103
And when you're barely bigger
than a golf ball,

237
00:19:49,062 --> 00:19:51,231
anything can be an obstacle.

238
00:19:51,315 --> 00:19:52,900
-[thuds]
-[music stops abruptly]

239
00:19:53,567 --> 00:19:54,610
[chirps]

240
00:19:54,693 --> 00:19:55,527
[music reprises]

241
00:19:55,611 --> 00:19:56,820
[all chirping]

242
00:19:56,904 --> 00:20:00,407
Their way may be blocked
by the lowest of logs…

243
00:20:02,534 --> 00:20:04,912
and the smallest of streams.

244
00:20:05,454 --> 00:20:07,039
[peeping]

245
00:20:08,540 --> 00:20:09,416
[music abates]

246
00:20:10,000 --> 00:20:13,879
For some, the journey is over
before it has even begun.

247
00:20:14,379 --> 00:20:16,381
[muffled cheeping]

248
00:20:16,924 --> 00:20:18,926
[music reprises]

249
00:20:22,137 --> 00:20:24,306
But not for this chick.

250
00:20:24,848 --> 00:20:27,559
[optimistic music playing]

251
00:20:28,060 --> 00:20:30,020
Finally, the beach.

252
00:20:31,313 --> 00:20:35,692
And it's the last land
it will touch for two years.

253
00:20:36,318 --> 00:20:38,320
[chirping]

254
00:20:41,323 --> 00:20:42,449
To find Mother,

255
00:20:42,950 --> 00:20:45,077
it calls into the darkness.

256
00:20:46,578 --> 00:20:48,580
[gentle piano music playing]

257
00:20:49,665 --> 00:20:50,874
[chirping]

258
00:20:57,089 --> 00:20:58,590
[chick peeping]

259
00:21:00,008 --> 00:21:01,426
Together again.

260
00:21:04,888 --> 00:21:07,516
But the chick has still not eaten.

261
00:21:12,604 --> 00:21:14,314
To reach the nearest food,

262
00:21:14,398 --> 00:21:16,149
they paddle nonstop

263
00:21:17,943 --> 00:21:21,363
for a remarkable 70 kilometers.

264
00:21:27,995 --> 00:21:30,539
Here, Mother can finally dive

265
00:21:30,622 --> 00:21:33,583
to collect
the chick's first meal of krill.

266
00:21:34,793 --> 00:21:37,170
But this is just a pit stop.

267
00:21:39,881 --> 00:21:43,427
The pair paddle
a further thousand kilometers.

268
00:21:46,430 --> 00:21:50,350
It's a month-long migration
to the rich northern seas

269
00:21:50,434 --> 00:21:51,810
where they can feast.

270
00:21:53,437 --> 00:21:58,400
It's probably the longest journey made
by any newly hatched bird.

271
00:21:58,900 --> 00:22:00,652
[music becomes rousing]

272
00:22:04,740 --> 00:22:07,743
And because the oceans
are so productive in summer,

273
00:22:08,702 --> 00:22:13,457
the murrelets can spend
virtually their entire lives at sea.

274
00:22:18,587 --> 00:22:21,923
-[single piano key plays]
-[metallic percussive sound reverberates]

275
00:22:26,470 --> 00:22:30,057
1600 kilometers northwest of Hawaii

276
00:22:31,183 --> 00:22:33,727
lies a remote speck of land,

277
00:22:35,437 --> 00:22:36,480
Laysan.

278
00:22:40,692 --> 00:22:44,321
Home to one of the world's
largest seabirds.

279
00:22:44,988 --> 00:22:46,907
[whimsical music playing]

280
00:22:48,700 --> 00:22:50,911
The Laysan albatross.

281
00:22:51,828 --> 00:22:52,913
[quacks, beak clacks]

282
00:22:55,791 --> 00:22:58,543
This chick, six weeks old,

283
00:22:58,627 --> 00:23:02,672
will become
a supreme long-distance traveler…

284
00:23:02,756 --> 00:23:04,216
[music becomes comical]

285
00:23:04,299 --> 00:23:09,513
…flying millions of kilometers
in its 60-year life.

286
00:23:11,181 --> 00:23:13,892
Now, however, at four months old,

287
00:23:13,975 --> 00:23:15,727
it's still flightless

288
00:23:16,561 --> 00:23:18,522
and going nowhere.

289
00:23:19,189 --> 00:23:20,524
[whimsical music playing]

290
00:23:23,527 --> 00:23:24,945
Unlike the murrelet,

291
00:23:25,028 --> 00:23:27,572
it depends on food being brought to it

292
00:23:28,156 --> 00:23:29,491
by its parents.

293
00:23:32,577 --> 00:23:36,456
But they could be fishing
up to 3,000 kilometers away.

294
00:23:37,874 --> 00:23:40,252
-So it may be waiting a while.

295
00:23:41,420 --> 00:23:43,880
-[comical music playing]
-Through pouring rain…

296
00:23:47,592 --> 00:23:49,136
…blasting winds…

297
00:23:51,721 --> 00:23:53,765
and baking heat.

298
00:23:55,225 --> 00:23:56,268
[music intensifies]

299
00:23:59,646 --> 00:24:00,564
[music ends]

300
00:24:03,316 --> 00:24:06,945
Every bird crossing the horizon
brings hope.

301
00:24:12,159 --> 00:24:14,077
-[shrieks]
-[expectant music playing]

302
00:24:14,161 --> 00:24:15,328
An albatross.

303
00:24:18,540 --> 00:24:20,083
But the wrong kind.

304
00:24:21,668 --> 00:24:22,961
A black-footed.

305
00:24:23,462 --> 00:24:24,796
[music intensifies]

306
00:24:25,297 --> 00:24:28,341
Though she has almost certainly
brought food.

307
00:24:28,425 --> 00:24:29,301
[clucking]

308
00:24:31,386 --> 00:24:34,848
Starving, the Laysan chick tries its luck.

309
00:24:34,931 --> 00:24:36,057
[shrieks]

310
00:24:37,809 --> 00:24:39,978
-[squealing]
-[shrieks]

311
00:24:42,272 --> 00:24:46,401
Clearly, for this mother,
it's family first.

312
00:24:50,071 --> 00:24:51,072
[peeps, beak clacks]

313
00:24:53,700 --> 00:24:54,826
[beak clacking]

314
00:24:56,036 --> 00:24:57,621
[somber music playing]

315
00:24:59,748 --> 00:25:02,167
But what looks like a lifeline…

316
00:25:02,250 --> 00:25:03,335
[peeping weakly]

317
00:25:03,418 --> 00:25:05,629
…could be a death sentence.

318
00:25:05,712 --> 00:25:06,755
[peeping stops]

319
00:25:08,757 --> 00:25:12,344
Across the island, chicks are dying.

320
00:25:12,886 --> 00:25:14,513
[music becomes more somber]

321
00:25:17,349 --> 00:25:20,685
There is now so much plastic in our oceans

322
00:25:22,020 --> 00:25:26,149
that it reaches
even the most remote islands on Earth.

323
00:25:27,359 --> 00:25:29,694
Carried here by the currents.

324
00:25:34,783 --> 00:25:38,286
The parents mistake
small floating pieces for food

325
00:25:38,787 --> 00:25:40,789
and bring it to their young,

326
00:25:40,872 --> 00:25:43,166
accidentally killing them.

327
00:25:43,250 --> 00:25:45,710
-[beak clacking]
-[music intensifies]

328
00:25:47,629 --> 00:25:50,590
It's almost certain
that every chick on the island

329
00:25:50,674 --> 00:25:52,634
has plastic in its stomach.

330
00:25:52,717 --> 00:25:53,552
[cheeps softly]

331
00:25:55,220 --> 00:25:58,640
Those that are fed too much
starve to death.

332
00:26:04,396 --> 00:26:07,607
Laysan albatross
are in the greatest danger.

333
00:26:09,484 --> 00:26:13,238
They consume more plastic
than any other seabird.

334
00:26:14,573 --> 00:26:17,242
And it's getting worse each year.

335
00:26:17,867 --> 00:26:19,536
[music becomes rousing]

336
00:26:26,668 --> 00:26:28,003
[music abates]

337
00:26:28,795 --> 00:26:31,840
At last, after nearly three weeks at sea…

338
00:26:34,050 --> 00:26:36,511
the chick's father returns.

339
00:26:40,432 --> 00:26:42,350
[whimsical music playing]

340
00:26:43,893 --> 00:26:45,395
[shrieking]

341
00:26:46,187 --> 00:26:48,523
Having spent so long apart,

342
00:26:50,275 --> 00:26:52,861
they need to renew their bond.

343
00:26:53,945 --> 00:26:55,447
[chirping, beak clacking]

344
00:26:55,530 --> 00:26:57,699
[chick peeping, beak clacking]

345
00:27:02,996 --> 00:27:07,000
This could be the last meal
the chick is ever given.

346
00:27:09,419 --> 00:27:12,964
And almost certainly contains plastic.

347
00:27:13,506 --> 00:27:15,675
[tense poignant music playing]

348
00:27:19,220 --> 00:27:20,263
[chick chirping]

349
00:27:23,308 --> 00:27:24,517
[chick chirping]

350
00:27:25,268 --> 00:27:26,895
[distant chirping]

351
00:27:26,978 --> 00:27:31,149
Its father returns
to a life traveling the Pacific.

352
00:27:32,984 --> 00:27:35,570
And the chick is left to its fate.

353
00:27:38,990 --> 00:27:41,409
But it's not over for him yet.

354
00:27:41,910 --> 00:27:43,912
[tense music playing]

355
00:27:44,788 --> 00:27:48,416
Albatrosses normally throw up
hard-to-digest parts,

356
00:27:48,500 --> 00:27:50,960
like squid beaks and bones.

357
00:27:55,006 --> 00:28:00,595
Ejecting lighters and bottle caps,
however, is more of a challenge.

358
00:28:03,515 --> 00:28:04,891
[music intensifies]

359
00:28:09,479 --> 00:28:10,605
[music crescendos]

360
00:28:11,106 --> 00:28:12,232
[cheeps, clacks beak]

361
00:28:13,024 --> 00:28:14,234
But this chick…

362
00:28:16,152 --> 00:28:17,487
is a survivor.

363
00:28:17,570 --> 00:28:20,490
-[whimsical French music playing]
-[cheeping]

364
00:28:21,825 --> 00:28:23,118
And with that,

365
00:28:23,201 --> 00:28:26,579
he is one step closer to takeoff.

366
00:28:28,456 --> 00:28:31,084
In a few weeks, on the right wind,

367
00:28:31,167 --> 00:28:34,462
he will finally be able
to make his big debut

368
00:28:34,546 --> 00:28:37,757
as one of the greatest ocean travelers.

369
00:28:42,220 --> 00:28:43,430
[music fades out]

370
00:28:44,931 --> 00:28:47,851
The course of our tilted planet
through space

371
00:28:47,934 --> 00:28:50,979
affects one place more than any other.

372
00:28:51,521 --> 00:28:54,190
[disquieting classical music playing]

373
00:28:57,110 --> 00:28:59,070
Summer in the North.

374
00:29:02,615 --> 00:29:05,410
The Arctic now faces the sun

375
00:29:05,493 --> 00:29:08,747
and is bathed in round-the-clock daylight,

376
00:29:08,830 --> 00:29:11,541
melting an ocean covered in ice.

377
00:29:12,041 --> 00:29:13,793
[music becomes rousing]

378
00:29:23,928 --> 00:29:26,097
To survive in this shifting world,

379
00:29:26,681 --> 00:29:29,350
life must move with it.

380
00:29:33,772 --> 00:29:34,606
[snorts]

381
00:29:35,356 --> 00:29:37,192
[music becomes menacing]

382
00:29:44,199 --> 00:29:45,241
[music abates]

383
00:29:50,914 --> 00:29:53,792
[growling]

384
00:29:59,881 --> 00:30:03,760
This young polar bear's home
changes so much each year

385
00:30:04,344 --> 00:30:07,055
that he can't keep to a limited territory.

386
00:30:11,184 --> 00:30:14,562
Instead, he must roam
for thousands of kilometers

387
00:30:14,646 --> 00:30:16,231
in search of seals.

388
00:30:17,315 --> 00:30:19,400
[quirky string music playing]

389
00:30:28,785 --> 00:30:32,247
But every summer,
as the ice begins to melt,

390
00:30:33,623 --> 00:30:35,959
he must spend less time walking…

391
00:30:39,838 --> 00:30:41,506
and more time swimming.

392
00:30:42,632 --> 00:30:44,467
[music becoming dramatic]

393
00:30:48,012 --> 00:30:51,099
Now, for almost eight hours a day.

394
00:30:59,566 --> 00:31:01,484
[snorting]

395
00:31:01,568 --> 00:31:05,697
He can smell prey from 30 kilometers away.

396
00:31:06,656 --> 00:31:07,699
[music abates]

397
00:31:09,534 --> 00:31:13,955
So he knows
that this bearded seal is nearby.

398
00:31:14,038 --> 00:31:14,998
[seal snorts]

399
00:31:17,584 --> 00:31:19,168
[tense music playing]

400
00:31:19,252 --> 00:31:21,462
[sniffing]

401
00:31:27,510 --> 00:31:30,263
The seal is unaware of the danger.

402
00:31:30,763 --> 00:31:31,598
[croaks softly]

403
00:31:32,557 --> 00:31:35,351
And the bear needs to keep it that way.

404
00:31:39,981 --> 00:31:41,357
[music intensifies]

405
00:31:57,332 --> 00:31:58,625
[music continues]

406
00:32:02,670 --> 00:32:03,630
[croaks]

407
00:32:03,713 --> 00:32:05,465
[music becomes chaotic]

408
00:32:09,510 --> 00:32:10,762
[music fades out]

409
00:32:11,262 --> 00:32:12,221
[snorts]

410
00:32:16,601 --> 00:32:20,730
The success rate
of hunting from the water is very low.

411
00:32:24,609 --> 00:32:26,945
[gentle classical music playing]

412
00:32:34,077 --> 00:32:35,620
[sniffing]

413
00:32:38,081 --> 00:32:40,083
[music becomes suspenseful]

414
00:32:41,292 --> 00:32:42,585
[music abates]

415
00:32:42,669 --> 00:32:45,588
Maybe third time will be lucky.

416
00:32:47,632 --> 00:32:49,008
[sniffs]

417
00:32:56,766 --> 00:32:58,059
[music continues]

418
00:33:11,280 --> 00:33:12,699
[music intensifies]

419
00:33:16,744 --> 00:33:18,496
[music becomes chaotic]

420
00:33:24,460 --> 00:33:25,753
[music fades out]

421
00:33:27,422 --> 00:33:28,923
[stillness]

422
00:33:32,719 --> 00:33:34,470
[subdued music playing]

423
00:33:38,891 --> 00:33:44,272
This young bear has yet to master
the art of stalking from the sea.

424
00:33:46,274 --> 00:33:48,359
But it's important that he does.

425
00:33:49,444 --> 00:33:52,905
He may have to rely on it
more and more each year.

426
00:33:55,450 --> 00:33:56,534
[yawns]

427
00:33:58,536 --> 00:34:00,455
Our climate is warming.

428
00:34:00,955 --> 00:34:02,790
[poignant music playing]

429
00:34:06,919 --> 00:34:09,881
And nowhere is this
having a greater effect

430
00:34:10,548 --> 00:34:12,050
than in the Arctic.

431
00:34:16,054 --> 00:34:18,806
This year, the temperature climbs

432
00:34:18,890 --> 00:34:22,769
to a staggering 38 degrees Celsius…

433
00:34:26,564 --> 00:34:29,442
melting sea ice faster than ever.

434
00:34:32,862 --> 00:34:36,991
And one Arctic animal
is affected more than most.

435
00:34:37,075 --> 00:34:38,326
[music continues]

436
00:34:47,251 --> 00:34:48,211
To feed,

437
00:34:48,294 --> 00:34:52,548
walrus need a combination
of a shallow seabed,

438
00:34:54,175 --> 00:34:55,843
abundant clams,

439
00:34:57,011 --> 00:35:00,765
and ice floes on which to rest.

440
00:35:02,934 --> 00:35:04,769
[walrus rasping, snorting]

441
00:35:10,983 --> 00:35:14,195
But there are now fewer places to do so.

442
00:35:16,364 --> 00:35:17,365
[music abates]

443
00:35:17,448 --> 00:35:21,119
Making each summer
more difficult than the last.

444
00:35:21,786 --> 00:35:22,703
[music resumes]

445
00:35:22,787 --> 00:35:25,456
Especially so for a new mother.

446
00:35:26,415 --> 00:35:28,042
[calf chirping]

447
00:35:29,293 --> 00:35:30,503
[mother rasps]

448
00:35:30,586 --> 00:35:35,466
Three days ago, she had to leave the herd
to give birth on her own.

449
00:35:38,469 --> 00:35:42,014
And since then,
she hasn't left her calf's side.

450
00:35:44,142 --> 00:35:46,394
-[calf grunts]
-[mother growls]

451
00:35:53,985 --> 00:35:57,530
Nursing mothers need
nearly twice as much food.

452
00:35:59,115 --> 00:36:03,286
But they can't leave their calves alone
while they themselves feed.

453
00:36:05,997 --> 00:36:08,875
So she must go in search of others

454
00:36:09,792 --> 00:36:12,253
to help her care for her young.

455
00:36:20,678 --> 00:36:24,140
A newborn walrus
is able to swim from day one.

456
00:36:28,561 --> 00:36:31,606
But he's not yet strong enough
to travel far.

457
00:36:35,151 --> 00:36:37,403
So, for his first journey,

458
00:36:38,529 --> 00:36:40,364
he hitches a ride.

459
00:36:46,370 --> 00:36:48,289
[music becomes whimsical]

460
00:36:53,419 --> 00:36:55,630
With fewer ice floes each year,

461
00:36:55,713 --> 00:36:58,341
they must swim further to find help.

462
00:37:03,137 --> 00:37:06,766
And until then, his mother can't feed.

463
00:37:15,274 --> 00:37:17,401
Even when they do find others,

464
00:37:17,944 --> 00:37:22,114
the ice must be low enough
for the calf to climb out.

465
00:37:24,033 --> 00:37:25,284
[rasps]

466
00:37:26,869 --> 00:37:27,954
Too high.

467
00:37:28,037 --> 00:37:29,997
[rasping]

468
00:37:38,506 --> 00:37:40,508
[growling]

469
00:37:43,010 --> 00:37:44,720
This looks just right.

470
00:37:51,102 --> 00:37:53,854
But with suitable ice in short supply,

471
00:37:53,938 --> 00:37:56,482
space is very limited.

472
00:37:58,359 --> 00:38:00,736
-[attacker growls]
-[mother grunting]

473
00:38:02,947 --> 00:38:05,324
[both snarling]

474
00:38:05,408 --> 00:38:06,867
[roaring]

475
00:38:12,164 --> 00:38:14,166
[snarling, roaring]

476
00:38:17,461 --> 00:38:21,132
-It's not the welcome they needed.
-[calf softly grunting]

477
00:38:26,971 --> 00:38:28,806
[poignant music playing]

478
00:38:32,226 --> 00:38:34,687
Even when there's enough ice,

479
00:38:34,770 --> 00:38:38,065
without anyone to help,
she is unable to feed

480
00:38:38,649 --> 00:38:40,401
and must stay with her calf.

481
00:38:44,155 --> 00:38:45,698
-[calf barks]
-[mother rasps]

482
00:38:51,662 --> 00:38:53,789
Their search must go on.

483
00:38:56,375 --> 00:39:00,171
The calf will depend on her
for the next three years.

484
00:39:02,631 --> 00:39:04,216
Wherever she goes,

485
00:39:05,051 --> 00:39:06,510
they will go together.

486
00:39:07,636 --> 00:39:09,013
[music intensifies]

487
00:39:11,682 --> 00:39:16,312
In the next decade, the summer sea ice
could disappear altogether.

488
00:39:24,403 --> 00:39:25,446
If that happens,

489
00:39:25,529 --> 00:39:28,783
even for the Arctic's
most seasoned travelers,

490
00:39:29,367 --> 00:39:31,619
there may be nowhere left to go.

491
00:39:32,286 --> 00:39:33,662
[music intensifies]

492
00:39:42,421 --> 00:39:44,298
[music fades out]

493
00:39:46,801 --> 00:39:48,302
In late June,

494
00:39:48,386 --> 00:39:52,348
the North feels the full impact
of the Earth's tilt

495
00:39:53,224 --> 00:39:56,936
and receives more daylight
than at any other time.

496
00:39:58,270 --> 00:40:00,773
And, in one corner of the Pacific,

497
00:40:00,856 --> 00:40:04,193
this creates the greatest opportunity
of the year.

498
00:40:07,905 --> 00:40:09,532
[somber music playing]

499
00:40:12,368 --> 00:40:13,536
For six months,

500
00:40:13,619 --> 00:40:18,040
Alaska's Bering Sea
appears lifeless and empty.

501
00:40:32,596 --> 00:40:34,682
Then, one day in June…

502
00:40:37,184 --> 00:40:39,395
all that changes.

503
00:40:43,482 --> 00:40:45,359
Humpback whales arrive

504
00:40:46,193 --> 00:40:48,195
after a month-long voyage…

505
00:40:52,283 --> 00:40:55,995
for the biggest event in their calendar.

506
00:40:58,414 --> 00:40:59,999
Thousands of them.

507
00:41:00,708 --> 00:41:02,918
[music becoming dramatic]

508
00:41:03,002 --> 00:41:04,670
Across the Pacific,

509
00:41:04,753 --> 00:41:07,256
other travelers are also on their way.

510
00:41:09,884 --> 00:41:13,095
Sooty shearwaters
race to get there in time…

511
00:41:17,099 --> 00:41:20,686
flying 1,000 kilometers a day nonstop.

512
00:41:23,063 --> 00:41:25,191
The occasion is so important,

513
00:41:25,274 --> 00:41:27,943
they come from the other side
of the world.

514
00:41:30,529 --> 00:41:32,907
At 65,000 kilometers,

515
00:41:33,407 --> 00:41:36,911
it's the longest animal migration
on Earth.

516
00:41:38,871 --> 00:41:39,830
[music intensifies]

517
00:41:43,584 --> 00:41:46,212
A million of them join the whales.

518
00:41:54,345 --> 00:41:56,430
All have come to feed.

519
00:42:02,895 --> 00:42:04,355
[music intensifies]

520
00:42:06,690 --> 00:42:10,986
It's one of the greatest gatherings
of life on Earth.

521
00:42:15,824 --> 00:42:17,785
Here, five months ago,

522
00:42:18,285 --> 00:42:21,205
there were just
seven hours of light a day.

523
00:42:23,958 --> 00:42:26,627
Now, there are 17.

524
00:42:29,171 --> 00:42:34,218
The change triggers an explosion
in the numbers of plankton and krill.

525
00:42:36,387 --> 00:42:41,517
For the whales, it may be the only time
they feed in the entire year.

526
00:42:43,644 --> 00:42:44,603
Over the summer,

527
00:42:45,604 --> 00:42:49,775
each scoops up 900 tons of food.

528
00:42:59,410 --> 00:43:03,539
They all have just 90 days
to eat as much as they can.

529
00:43:09,295 --> 00:43:11,297
Soon, the days will shorten

530
00:43:11,797 --> 00:43:14,466
and bring an end to the great feast.

531
00:43:16,385 --> 00:43:19,305
Then, every one of them will return south.

532
00:43:22,141 --> 00:43:25,853
The opportunities brought
by our tilted planet's journey

533
00:43:25,936 --> 00:43:29,023
can be enormous yet fleeting.

534
00:43:29,857 --> 00:43:30,899
[music abates]

535
00:43:33,193 --> 00:43:35,779
After a month of long summer days,

536
00:43:36,280 --> 00:43:39,825
temperatures in the North Pacific
are reaching their peak.

537
00:43:45,497 --> 00:43:48,542
An ocean predator detects the change

538
00:43:48,626 --> 00:43:50,669
and sets a new course.

539
00:43:50,753 --> 00:43:52,880
[suspenseful music playing]

540
00:44:01,597 --> 00:44:02,931
A tiger shark

541
00:44:03,432 --> 00:44:07,394
on a thousand-kilometer odyssey
across the Pacific.

542
00:44:14,526 --> 00:44:16,987
Guided by the Earth's magnetic field,

543
00:44:18,113 --> 00:44:21,367
she swims in a straight line
towards her target…

544
00:44:25,412 --> 00:44:27,414
Laysan Island.

545
00:44:30,042 --> 00:44:31,710
And she's not the only one.

546
00:44:33,212 --> 00:44:34,546
[music intensifies]

547
00:44:36,090 --> 00:44:40,844
This species makes some
of the longest journeys of all sharks.

548
00:44:43,389 --> 00:44:47,643
And hunts a bigger range of animals
than any other.

549
00:44:49,269 --> 00:44:50,688
Including even

550
00:44:51,563 --> 00:44:52,523
birds.

551
00:44:53,065 --> 00:44:54,108
[music abates]

552
00:44:58,904 --> 00:45:02,408
The Laysan albatross chick hasn't eaten

553
00:45:02,491 --> 00:45:06,787
since he was abandoned by his parents
two weeks ago.

554
00:45:06,870 --> 00:45:09,164
[whimsical French music playing]

555
00:45:10,582 --> 00:45:11,792
To find food,

556
00:45:12,292 --> 00:45:15,045
he must now leave the island.

557
00:45:17,589 --> 00:45:18,799
[chirping]

558
00:45:18,882 --> 00:45:23,679
But the world's largest seabirds
need a lot of lift.

559
00:45:24,430 --> 00:45:25,681
[music fades out]

560
00:45:26,265 --> 00:45:28,642
That could come at any moment.

561
00:45:33,856 --> 00:45:39,570
In July, the high ocean temperatures
generate tropical storms at sea…

562
00:45:43,991 --> 00:45:46,744
bringing wind to Laysan

563
00:45:47,911 --> 00:45:51,790
and the young albatross
a ticket out of here.

564
00:45:51,874 --> 00:45:54,168
[dramatic string music playing]

565
00:45:58,922 --> 00:46:01,049
The breeze continues to build

566
00:46:02,134 --> 00:46:05,804
until there's enough
to lift even an albatross.

567
00:46:10,017 --> 00:46:14,646
And the black-footed chicks
are always first to go.

568
00:46:17,900 --> 00:46:19,276
[music intensifies]

569
00:46:25,699 --> 00:46:27,618
[chirping]

570
00:46:28,327 --> 00:46:30,120
[music abruptly ends]

571
00:46:30,204 --> 00:46:33,290
A chick's first flight
is never a long one.

572
00:46:34,208 --> 00:46:36,168
[disquieting music playing]

573
00:46:37,920 --> 00:46:40,881
And here, it's often their last.

574
00:46:41,590 --> 00:46:45,761
[music becomes dramatic, fades out]

575
00:46:49,932 --> 00:46:51,183
[chirping softly]

576
00:46:52,309 --> 00:46:55,687
The tiger sharks have arrived.

577
00:46:55,771 --> 00:46:57,397
[menacing music playing]

578
00:47:01,276 --> 00:47:03,862
[music intensifies, abates]

579
00:47:07,533 --> 00:47:08,367
[squawking]

580
00:47:12,621 --> 00:47:14,498
And they are very effective.

581
00:47:15,123 --> 00:47:15,999
[music reprises]

582
00:47:24,174 --> 00:47:25,467
[music fades out]

583
00:47:27,261 --> 00:47:32,015
For the young albatross,
it's not exactly encouraging.

584
00:47:33,517 --> 00:47:35,853
-But it's now…
-[quirky dramatic music playing]

585
00:47:35,936 --> 00:47:36,770
…or never.

586
00:47:46,905 --> 00:47:48,907
If he reaches the open ocean,

587
00:47:49,491 --> 00:47:53,453
he may not touch land again
for five years.

588
00:47:55,706 --> 00:47:58,584
But there is no room for error.

589
00:48:00,127 --> 00:48:01,545
[music intensifies]

590
00:48:07,843 --> 00:48:10,596
Time to throw caution to the wind.

591
00:48:12,806 --> 00:48:13,891
[music builds]

592
00:48:13,974 --> 00:48:17,144
Time to fly.

593
00:48:17,227 --> 00:48:19,479
[music crescendoes]

594
00:48:19,563 --> 00:48:20,856
[music fades out]

595
00:48:21,356 --> 00:48:23,358
[theme tune playing]

596
00:49:11,406 --> 00:49:13,408
[music crescendoes]

597
00:49:47,693 --> 00:49:49,403
[music ends]