1
00:00:07,480 --> 00:00:10,800
As a new year starts,

2
00:00:10,800 --> 00:00:13,960
a new life begins.

3
00:00:19,000 --> 00:00:23,960
After nearly two months
of careful incubation,

4
00:00:23,960 --> 00:00:25,960
this king penguin chick

5
00:00:25,960 --> 00:00:29,960
is ready to face the world.

6
00:00:29,960 --> 00:00:32,960
A world she'll soon discover

7
00:00:32,960 --> 00:00:35,960
keeps changing all the time.

8
00:00:43,960 --> 00:00:45,960
In the far south,

9
00:00:45,960 --> 00:00:48,960
the days will soon get shorter...

10
00:00:49,960 --> 00:00:52,800
..the weather will worsen.

11
00:00:56,480 --> 00:01:00,960
And this little chick
must learn to adapt

12
00:01:00,960 --> 00:01:06,160
if she's to survive
her first year on Earth.

13
00:01:10,960 --> 00:01:13,960
In 365 days from now,

14
00:01:13,960 --> 00:01:17,960
the Earth will have come
full circle round the sun.

15
00:01:20,960 --> 00:01:23,960
As we journey through space,

16
00:01:23,960 --> 00:01:26,640
around this ball of fire,

17
00:01:26,640 --> 00:01:29,640
it fuels extraordinary change...

18
00:01:30,960 --> 00:01:34,480
..creating the seasons
that alter the worlds

19
00:01:34,480 --> 00:01:36,960
of almost every animal
on our planet.

20
00:01:41,960 --> 00:01:43,960
Determining when they move...

21
00:01:46,800 --> 00:01:47,960
..fight...

22
00:01:50,960 --> 00:01:52,960
..and when they raise a family.

23
00:01:57,640 --> 00:01:59,800
In this programme...

24
00:02:00,960 --> 00:02:04,960
..we'll see how animals
use incredible strategies

25
00:02:04,960 --> 00:02:07,960
to cope with
their ever-changing world...

26
00:02:09,960 --> 00:02:14,960
..as we travel full circle
through every season

27
00:02:14,960 --> 00:02:18,000
in a year on planet Earth.

28
00:02:52,960 --> 00:02:55,960
Nowhere in the Northern Hemisphere

29
00:02:55,960 --> 00:02:58,480
is winter as extreme

30
00:02:58,480 --> 00:03:00,960
or felt more harshly

31
00:03:00,960 --> 00:03:02,960
than in the High Arctic.

32
00:03:11,960 --> 00:03:14,960
This polar bear mum and cub

33
00:03:14,960 --> 00:03:19,800
are seeing the new year in...
in darkness.

34
00:03:20,960 --> 00:03:24,960
A night that will last
another 45 days.

35
00:03:49,000 --> 00:03:50,960
At the start of the year,

36
00:03:50,960 --> 00:03:53,960
the Northern Hemisphere is tilted

37
00:03:53,960 --> 00:03:56,960
almost as far away from the sun
as it can be.

38
00:03:57,960 --> 00:03:59,960
It's cold and dark.

39
00:04:03,960 --> 00:04:06,960
Food is thin on the ground.

40
00:04:09,960 --> 00:04:12,960
And not everyone will survive
long enough to see the sun

41
00:04:12,960 --> 00:04:15,960
when it eventually rises again.

42
00:04:25,960 --> 00:04:28,960
But even in these darkest months,

43
00:04:28,960 --> 00:04:31,960
the sun's presence
is still evident.

44
00:04:38,960 --> 00:04:43,800
As solar winds collide
with the Earth's magnetic field,

45
00:04:43,800 --> 00:04:45,160
they create a light show

46
00:04:45,160 --> 00:04:47,960
that's truly out of this world.

47
00:04:53,960 --> 00:04:56,960
The northern lights.

48
00:05:02,960 --> 00:05:04,160
This spectacle

49
00:05:04,160 --> 00:05:07,960
is hundreds of kilometres
above the Earth's surface.

50
00:05:12,960 --> 00:05:17,160
But it's only visible
when the sky is at its darkest.

51
00:05:23,960 --> 00:05:25,800
In February,

52
00:05:25,800 --> 00:05:29,320
the Northern Hemisphere
begins to face towards the sun.

53
00:05:36,960 --> 00:05:39,960
Days start to get longer
and warmer...

54
00:05:42,960 --> 00:05:45,960
..and winter
in these wooded valleys

55
00:05:45,960 --> 00:05:47,960
begins to lose its grip.

56
00:05:52,960 --> 00:05:55,960
But until it's gone for good,

57
00:05:55,960 --> 00:06:00,960
food for this red squirrel
is hard to come by.

58
00:06:09,960 --> 00:06:11,960
Squirrels don't hibernate.

59
00:06:13,960 --> 00:06:15,960
So, to get through winter,

60
00:06:15,960 --> 00:06:18,960
he relies on forward planning

61
00:06:18,960 --> 00:06:21,960
and a very good memory.

62
00:06:26,160 --> 00:06:29,960
In autumn,
he buried about 3,000 nuts...

63
00:06:31,320 --> 00:06:33,960
..carefully grouped
according to type.

64
00:06:35,960 --> 00:06:40,960
Now he must remember
where he left them.

65
00:06:43,960 --> 00:06:46,960
To help him, his hippocampus,

66
00:06:46,960 --> 00:06:49,960
the part of the brain
concerned with memory,

67
00:06:49,960 --> 00:06:51,960
has expanded.

68
00:06:55,160 --> 00:06:57,000
It's the same part of the brain

69
00:06:57,000 --> 00:06:59,640
that's first affected
with Alzheimer's,

70
00:06:59,640 --> 00:07:02,960
and researchers are hoping
we can learn more about it

71
00:07:02,960 --> 00:07:05,800
from studying squirrels.

72
00:07:08,640 --> 00:07:11,960
Whatever he's doing, it's working.

73
00:07:15,960 --> 00:07:16,960
Erm, mostly.

74
00:07:27,800 --> 00:07:30,960
Do you ever get that feeling
you're being watched?

75
00:07:37,960 --> 00:07:39,960
In late winter,

76
00:07:39,960 --> 00:07:42,960
most squirrels' stashes are empty,

77
00:07:42,960 --> 00:07:45,960
so thieves
are always on the lookout...

78
00:07:48,960 --> 00:07:52,800
..and will steal anything
they can get their paws on.

79
00:08:41,960 --> 00:08:46,960
Finally, he can finish
his breakfast in peace.

80
00:08:48,960 --> 00:08:51,960
In these bitterly cold months,

81
00:08:51,960 --> 00:08:54,960
competition for food
is at its fiercest.

82
00:08:58,960 --> 00:09:02,960
Nowhere more so
than on the east coast of Japan.

83
00:09:06,480 --> 00:09:08,000
Steller's sea eagles

84
00:09:08,000 --> 00:09:11,960
are one of the most powerful raptors
in the world.

85
00:09:14,960 --> 00:09:17,960
And with a wingspan
of over two metres,

86
00:09:17,960 --> 00:09:19,960
one of the largest.

87
00:09:22,960 --> 00:09:26,960
Now that much of the sea
is frozen solid,

88
00:09:26,960 --> 00:09:28,960
these big bruisers

89
00:09:28,960 --> 00:09:32,960
resort to underhand
means to get fish.

90
00:10:15,960 --> 00:10:17,960
Harmony will only be restored

91
00:10:17,960 --> 00:10:19,960
when the temperature rises,

92
00:10:19,960 --> 00:10:21,960
sea ice melts

93
00:10:21,960 --> 00:10:24,960
and fishing gets easier again.

94
00:10:41,000 --> 00:10:46,960
Our planet is now three months into
its annual journey around the sun.

95
00:10:50,960 --> 00:10:53,960
As days in the Northern Hemisphere

96
00:10:53,960 --> 00:10:55,960
continue to get longer and warmer...

97
00:10:59,960 --> 00:11:04,960
..in the Southern Hemisphere,
they're getting shorter and colder.

98
00:11:19,960 --> 00:11:23,960
The king penguin chick is
now four months old,

99
00:11:23,960 --> 00:11:27,000
and beginning to spread her wings.

100
00:11:29,960 --> 00:11:31,640
To adapt to the cold,

101
00:11:31,640 --> 00:11:36,160
she's become the proud owner
of this fine feather coat,

102
00:11:36,160 --> 00:11:40,160
and is already
50 times her birth weight...

103
00:11:41,960 --> 00:11:45,960
..thanks to plenty of fish takeaways
from her parents.

104
00:11:56,960 --> 00:12:00,960
To keep their not-so-little one fed,

105
00:12:00,960 --> 00:12:03,960
Mum and Dad
are falling over backwards

106
00:12:03,960 --> 00:12:06,960
with constant trips to the sea.

107
00:12:17,640 --> 00:12:23,480
As parents, it can sometimes
feel like you're doing all the work.

108
00:12:32,320 --> 00:12:35,960
But the chick's months
of being waited on

109
00:12:35,960 --> 00:12:37,960
are coming to and end.

110
00:12:41,320 --> 00:12:45,000
As the days continue to get shorter
this far south,

111
00:12:45,000 --> 00:12:47,960
the water is getting colder.

112
00:12:52,960 --> 00:12:54,960
Currents are shifting

113
00:12:54,960 --> 00:12:59,160
and prime feeding areas
are moving further away.

114
00:13:03,960 --> 00:13:08,960
Soon, her parents will be gone
for months on end,

115
00:13:08,960 --> 00:13:13,640
and the chick
will be left to fend for herself.

116
00:13:20,320 --> 00:13:23,960
As life in the Southern Hemisphere
gets harder,

117
00:13:23,960 --> 00:13:28,960
in the Norther Hemisphere,
it's getting easier.

118
00:13:33,960 --> 00:13:37,960
Spring is in full flow.

119
00:13:46,960 --> 00:13:50,960
Day length
is now longer than night...

120
00:13:51,960 --> 00:13:56,960
..and solar energy
reaching the ground has increased.

121
00:14:01,960 --> 00:14:03,960
A splash of rain,

122
00:14:03,960 --> 00:14:08,960
and the north transforms
into a sea of colour.

123
00:14:11,960 --> 00:14:13,960
New growth.

124
00:14:15,960 --> 00:14:17,960
New life.

125
00:14:19,960 --> 00:14:22,960
And new opportunities.

126
00:14:34,480 --> 00:14:38,960
On the largest, highest plateau
in the world,

127
00:14:38,960 --> 00:14:42,960
the locals
have never had it so good.

128
00:14:45,960 --> 00:14:49,960
Thanks to the new spring growth,

129
00:14:49,960 --> 00:14:52,960
these pikas are having a feast...

130
00:14:54,800 --> 00:14:56,960
..and a baby boom.

131
00:14:59,960 --> 00:15:04,160
And pikas aren't the only
ones to thrive in spring.

132
00:15:05,960 --> 00:15:10,320
This season
is enough to put a very big smile

133
00:15:10,320 --> 00:15:13,960
on one hungry resident's face.

134
00:15:17,960 --> 00:15:23,000
The Tibetan fox
has the widest gape of any fox.

135
00:15:23,000 --> 00:15:26,960
All the better to eat pika with.

136
00:15:31,960 --> 00:15:37,960
In fact, over 90% of
this wily predator's diet is pika.

137
00:15:43,960 --> 00:15:46,320
When she can catch one.

138
00:15:48,960 --> 00:15:51,960
Pikas have hundreds of boltholes,

139
00:15:51,960 --> 00:15:56,960
and are quick to warn each other
when they spot danger.

140
00:16:14,640 --> 00:16:17,960
Teamwork keeps them one step ahead.

141
00:16:31,640 --> 00:16:34,960
But not everyone's paying attention.

142
00:16:40,960 --> 00:16:44,960
The fox hunts
every morning and evening,

143
00:16:44,960 --> 00:16:47,320
not just for her,

144
00:16:47,320 --> 00:16:50,960
but for her three
eight-week-old cubs.

145
00:16:57,960 --> 00:17:01,960
Usually the father helps
to feed his cubs.

146
00:17:03,960 --> 00:17:05,960
But he has disappeared,

147
00:17:05,960 --> 00:17:08,960
leaving Mum
to bring them up on her own.

148
00:17:11,960 --> 00:17:13,960
Not easy.

149
00:17:14,960 --> 00:17:18,960
But with so much food around,
and a hard-working mum,

150
00:17:18,960 --> 00:17:21,960
the cubs have a good chance
of making it.

151
00:17:25,960 --> 00:17:28,960
Across the Northern Hemisphere,

152
00:17:28,960 --> 00:17:31,960
this is the time to start a family.

153
00:17:33,960 --> 00:17:39,640
Though one animal
is a little slow to get going.

154
00:17:42,960 --> 00:17:46,960
Up here at 2,000 metres,

155
00:17:46,960 --> 00:17:49,000
it can feel more like winter.

156
00:17:52,480 --> 00:17:53,960
But at last,

157
00:17:53,960 --> 00:17:58,960
the sun has pushed the temperature
up to five degrees,

158
00:17:58,960 --> 00:18:03,960
making all the difference
to one cold-blooded creature.

159
00:18:08,960 --> 00:18:11,960
A common European frog.

160
00:18:14,960 --> 00:18:18,960
He's been hibernating
in an underground stream

161
00:18:18,960 --> 00:18:20,960
for over six months.

162
00:18:21,960 --> 00:18:25,960
Now he's desperate to get a mate.

163
00:18:25,960 --> 00:18:30,160
And there, in that pond,
is where the party is.

164
00:18:32,960 --> 00:18:35,960
So, he had better hop to it.

165
00:18:39,960 --> 00:18:42,960
He needs to move in daylight

166
00:18:42,960 --> 00:18:45,960
to make the most
of the sun's warmth.

167
00:18:47,960 --> 00:18:50,320
But his muscles are slow to warm up.

168
00:18:53,800 --> 00:18:55,960
Hot-blooded in passion,

169
00:18:55,960 --> 00:18:58,960
cold-blooded in body.

170
00:19:02,160 --> 00:19:04,960
A frustrating combination.

171
00:19:17,960 --> 00:19:19,960
Other males have emerged.

172
00:19:25,960 --> 00:19:28,800
The first to the pond

173
00:19:28,800 --> 00:19:30,960
will have the pick of the females.

174
00:19:52,960 --> 00:19:55,960
But our guy has... run out of steam.

175
00:20:01,000 --> 00:20:03,960
The others are pairing up.

176
00:20:07,960 --> 00:20:11,960
Try as he might, he just can't move.

177
00:20:14,960 --> 00:20:18,960
As the sun's powerful rays
beam down,

178
00:20:18,960 --> 00:20:23,800
slowly his body
starts to warm again.

179
00:20:24,960 --> 00:20:27,960
The last five metres

180
00:20:27,960 --> 00:20:29,960
takes all he's got.

181
00:20:40,160 --> 00:20:41,960
He may be late...

182
00:20:46,960 --> 00:20:50,960
..but things have turned out
pretty well after all.

183
00:20:53,960 --> 00:20:56,960
It's not just his world

184
00:20:56,960 --> 00:20:57,960
that's hotting up.

185
00:21:07,320 --> 00:21:11,960
We are now halfway through
our annual orbit...

186
00:21:12,960 --> 00:21:17,960
..and the Northern Hemisphere
is tilting towards the sun.

187
00:21:20,960 --> 00:21:22,960
Summer has begun.

188
00:21:26,960 --> 00:21:30,960
As we enter
the hottest season of the year,

189
00:21:30,960 --> 00:21:35,960
life prepares to adapt again
to the changes it brings.

190
00:21:50,960 --> 00:21:54,960
For some, this is a time to feast

191
00:21:54,960 --> 00:21:57,960
and a chance to store energy...

192
00:21:59,960 --> 00:22:02,960
..as food becomes more abundant.

193
00:22:10,960 --> 00:22:15,000
Nowhere more so
than in Southwest China.

194
00:22:21,320 --> 00:22:23,960
Here, the landscape is dominated

195
00:22:23,960 --> 00:22:27,000
by the fastest-growing plant
on the planet.

196
00:22:30,960 --> 00:22:32,960
Bamboo.

197
00:22:38,960 --> 00:22:44,960
In summer, it can grow
a staggering one metre a day.

198
00:22:48,960 --> 00:22:52,960
Giving one animal
the vital chance it needs

199
00:22:52,960 --> 00:22:54,960
to pile on the pounds.

200
00:23:02,960 --> 00:23:05,960
The giant panda.

201
00:23:11,960 --> 00:23:16,960
In winter, this mum has to eat
poor-quality bamboo leaves.

202
00:23:20,960 --> 00:23:24,960
But now she can eat
as many nutritious shoots

203
00:23:24,960 --> 00:23:26,320
as she can manage.

204
00:23:32,640 --> 00:23:33,960
As her diet changes,

205
00:23:33,960 --> 00:23:36,960
so too do her gut bacteria,

206
00:23:36,960 --> 00:23:41,640
helping her lay down fat
for leaner months ahead.

207
00:23:45,960 --> 00:23:47,960
While she tucks in,

208
00:23:47,960 --> 00:23:52,960
her 11-month-old cub
takes the chance to explore.

209
00:23:57,960 --> 00:24:03,960
Apart from when they're little,
all giant pandas live alone.

210
00:24:06,960 --> 00:24:11,960
The cub will be independent
in just five months,

211
00:24:11,960 --> 00:24:15,160
and is starting to test
how it feels.

212
00:24:20,960 --> 00:24:25,160
Although shoots
are higher quality than leaves,

213
00:24:25,160 --> 00:24:29,960
Mum still needs to eat
up to half her body weight a day

214
00:24:29,960 --> 00:24:31,960
to get enough nutrients.

215
00:24:34,960 --> 00:24:38,960
Her cub, on the other hand,
isn't yet weaned.

216
00:24:41,960 --> 00:24:44,960
And although he's old enough
to eat solid food,

217
00:24:44,960 --> 00:24:49,960
for him, it's...
take it or leave it.

218
00:24:53,960 --> 00:24:58,800
Her meal could stretch on
for 14 hours.

219
00:25:01,960 --> 00:25:04,960
But on a diet
of Mum's fat-rich milk,

220
00:25:04,960 --> 00:25:07,960
he can afford to take it easy.

221
00:25:23,160 --> 00:25:27,960
Mum has four months to fatten up
before winter.

222
00:25:41,960 --> 00:25:43,960
But some things in life

223
00:25:43,960 --> 00:25:46,960
are even more important than bamboo.

224
00:25:57,160 --> 00:26:01,640
This is the pair's
last summer together.

225
00:26:06,960 --> 00:26:10,960
Soon, this little bear
must learn to live on his own.

226
00:26:16,960 --> 00:26:19,960
Until then, Mum will do all she can

227
00:26:19,960 --> 00:26:23,480
to help him
stand on his own four feet.

228
00:26:34,800 --> 00:26:38,960
Summer here
is the wettest time of year.

229
00:26:40,960 --> 00:26:43,320
Over 70cm of rain

230
00:26:43,320 --> 00:26:45,960
can fall in a single month.

231
00:26:48,640 --> 00:26:50,160
While in the south,

232
00:26:50,160 --> 00:26:53,160
in Australia's Northern Territory,

233
00:26:53,160 --> 00:26:55,960
there is serious drought.

234
00:26:59,960 --> 00:27:05,960
Out here, bush fires
can spread 25km each day.

235
00:27:07,960 --> 00:27:10,800
Months without rain,

236
00:27:10,800 --> 00:27:14,960
and dry grasslands,
are like a tinderbox.

237
00:27:14,960 --> 00:27:17,960
It only takes a tiny spark

238
00:27:17,960 --> 00:27:20,960
to set
these flammable plants alight.

239
00:27:20,960 --> 00:27:26,960
Add wind...
and the woodland is ablaze.

240
00:27:32,960 --> 00:27:36,640
Those that can flee for their lives.

241
00:27:41,960 --> 00:27:44,960
But not everyone has the nerve.

242
00:27:45,960 --> 00:27:48,960
Or the know-how.

243
00:27:51,640 --> 00:27:54,960
These hooded parrot chicks

244
00:27:54,960 --> 00:27:56,160
are one month old.

245
00:28:00,960 --> 00:28:05,960
They're getting ready to fledge,
but they've left it too late.

246
00:28:08,160 --> 00:28:09,960
As well as the flames,

247
00:28:09,960 --> 00:28:13,160
deadly fire hawks
are on the prowl...

248
00:28:14,960 --> 00:28:17,960
..looking for creatures
flushed out by the fire.

249
00:28:26,960 --> 00:28:29,960
The chicks have missed their chance.

250
00:28:48,960 --> 00:28:54,640
Bush fires kill billions of animals
every year...

251
00:28:59,960 --> 00:29:04,960
..which is why the chicks' parents
have planned ahead.

252
00:29:13,960 --> 00:29:16,480
The home they've chosen,

253
00:29:16,480 --> 00:29:19,960
this termite mound
made of sand and clay,

254
00:29:19,960 --> 00:29:21,960
is fireproof.

255
00:29:30,480 --> 00:29:35,960
And this scorched ground is,
in fact, what the chicks need

256
00:29:35,960 --> 00:29:37,960
to tempt them out.

257
00:29:41,640 --> 00:29:45,160
The grasses
have dropped their seeds,

258
00:29:45,160 --> 00:29:50,800
just in time for the parrots'
first meal out as a family.

259
00:29:53,960 --> 00:29:56,960
In less than a week,
the chicks will leave home...

260
00:29:58,960 --> 00:30:01,960
..and the parents
will be empty-nesters

261
00:30:01,960 --> 00:30:04,960
until they breed again next year.

262
00:30:09,960 --> 00:30:12,960
The winds that gave fuel
to these fires

263
00:30:12,960 --> 00:30:15,960
are the south-easterly trade winds.

264
00:30:16,960 --> 00:30:18,960
Vast currents of air

265
00:30:18,960 --> 00:30:22,640
that are carried west
as the Earth rotates,

266
00:30:22,640 --> 00:30:25,960
and pulled north
towards the heat of the sun.

267
00:30:28,960 --> 00:30:31,960
As they sweep over the Indian Ocean,

268
00:30:31,960 --> 00:30:34,960
they change the direction
of the currents beneath...

269
00:30:36,960 --> 00:30:38,800
..creating conditions

270
00:30:38,800 --> 00:30:43,000
for the sea's most important
food source to thrive.

271
00:30:44,640 --> 00:30:46,480
Plankton.

272
00:30:46,480 --> 00:30:49,480
Microscopic plants and animals.

273
00:30:50,480 --> 00:30:54,480
The staple food
of almost every marine ecosystem.

274
00:31:00,960 --> 00:31:03,160
The miniature plants

275
00:31:03,160 --> 00:31:06,960
produce over half of the oxygen
that we breathe.

276
00:31:18,320 --> 00:31:20,960
On this coral reef,

277
00:31:20,960 --> 00:31:22,960
they feed fish.

278
00:31:24,480 --> 00:31:25,960
From the smallest...

279
00:31:29,960 --> 00:31:30,960
..to the largest.

280
00:31:46,960 --> 00:31:49,800
Reef manta rays,

281
00:31:49,800 --> 00:31:51,960
with a four-metre wingspan,

282
00:31:51,960 --> 00:31:55,960
make a seasonal migration
around these atolls,

283
00:31:55,960 --> 00:31:57,960
following the plankton.

284
00:32:16,960 --> 00:32:21,960
Swimming one behind the other,
they catch plankton

285
00:32:21,960 --> 00:32:24,960
from the slipstream
of the manta in front.

286
00:32:26,960 --> 00:32:29,960
And as the leader turns,

287
00:32:29,960 --> 00:32:33,000
they form what's known as
a feeding cyclone...

288
00:32:34,960 --> 00:32:37,960
..channelling
the tiny plants and animals

289
00:32:37,960 --> 00:32:40,800
into their super-sized mouths.

290
00:32:46,960 --> 00:32:49,960
These gentle giants

291
00:32:49,960 --> 00:32:53,960
need a constant flow of water
to breathe.

292
00:32:56,960 --> 00:32:59,960
So, with their wing-like fins,

293
00:32:59,960 --> 00:33:02,480
these birds of the sea

294
00:33:02,480 --> 00:33:04,960
are always on the move...

295
00:33:05,960 --> 00:33:09,960
..returning to this bay
year after year

296
00:33:09,960 --> 00:33:13,320
in numbers up to 5,000 strong

297
00:33:13,320 --> 00:33:17,960
for the biggest manta feeding
aggregation in the world.

298
00:33:23,960 --> 00:33:28,480
While the mantas
are free to follow their food...

299
00:33:29,960 --> 00:33:31,960
..in the same ocean,

300
00:33:31,960 --> 00:33:34,640
6,000km south...

301
00:33:35,960 --> 00:33:40,000
..the king penguin chick
is close to starving.

302
00:33:56,960 --> 00:33:59,480
It's been four months

303
00:33:59,480 --> 00:34:02,960
since her parents left
to find food,

304
00:34:02,960 --> 00:34:06,960
and she hasn't eaten
in all that time.

305
00:34:16,960 --> 00:34:20,960
Most parents have returned
with bellies full of fish.

306
00:34:25,960 --> 00:34:29,320
But hers
have yet to make an appearance.

307
00:34:35,960 --> 00:34:37,960
In response to fasting,

308
00:34:37,960 --> 00:34:41,960
her metabolism and growth rate
have slowed.

309
00:34:43,960 --> 00:34:45,960
Beneath all that fluff,

310
00:34:45,960 --> 00:34:49,960
she's lost 70% of her body weight...

311
00:34:50,960 --> 00:34:54,160
..and is now just 4kg.

312
00:34:58,960 --> 00:35:02,960
King penguin chicks
can survive without food

313
00:35:02,960 --> 00:35:04,960
longer than any other bird.

314
00:35:07,960 --> 00:35:13,960
But each year, half starve to death
waiting for their parents to return.

315
00:35:34,960 --> 00:35:39,960
But her mum and dad
aren't going to let that happen.

316
00:35:41,960 --> 00:35:45,960
They arrive in the nick of time.

317
00:36:03,960 --> 00:36:05,960
With her parents' help,

318
00:36:05,960 --> 00:36:09,800
this chick
has made it to eight months.

319
00:36:11,960 --> 00:36:12,960
The time it's taken

320
00:36:12,960 --> 00:36:17,960
for our planet to journey
two thirds of its way round the sun.

321
00:36:22,960 --> 00:36:24,960
By the time it's gone full circle,

322
00:36:24,960 --> 00:36:28,640
this chick must be ready
to go it alone.

323
00:36:44,160 --> 00:36:48,320
As we enter
the final leg of our journey,

324
00:36:48,320 --> 00:36:53,960
in the north,
the sun's rays become less intense.

325
00:36:55,960 --> 00:36:57,960
Temperatures fall.

326
00:36:58,960 --> 00:37:02,960
And this triggers
a season of spectacular change.

327
00:37:10,960 --> 00:37:12,000
Autumn.

328
00:37:18,320 --> 00:37:21,960
And it's not only the leaves
that are changing colour.

329
00:37:24,960 --> 00:37:26,960
In Northeast India,

330
00:37:26,960 --> 00:37:29,160
heads are turning.

331
00:37:38,960 --> 00:37:44,960
Because the one and only male
in this group of golden langurs

332
00:37:44,960 --> 00:37:47,960
has never looked so good.

333
00:37:50,960 --> 00:37:54,960
For most of the year,
he's creamy-white in colour.

334
00:37:54,960 --> 00:38:00,960
But in the breeding season,
his coat turns a stunning gold,

335
00:38:00,960 --> 00:38:02,960
making him irresistible

336
00:38:02,960 --> 00:38:05,960
to the troop's six females.

337
00:38:11,960 --> 00:38:13,960
These shy langurs

338
00:38:13,960 --> 00:38:15,960
are becoming
increasingly endangered.

339
00:38:17,960 --> 00:38:20,960
As their habitat has fragmented,

340
00:38:20,960 --> 00:38:25,800
their numbers have halved
in the last 30 years.

341
00:38:29,960 --> 00:38:33,960
There are only 6,500 left
in the world.

342
00:38:41,640 --> 00:38:43,960
But this male is doing his best

343
00:38:43,960 --> 00:38:45,960
to get those numbers rising.

344
00:38:53,960 --> 00:38:57,960
And he's not the only one
feeling hot-blooded right now.

345
00:39:04,960 --> 00:39:07,960
As temperatures continue to fall,

346
00:39:07,960 --> 00:39:12,960
in Northern Norway,
this alpha male musk ox

347
00:39:12,960 --> 00:39:15,480
prepares to breed.

348
00:39:18,960 --> 00:39:23,960
He's responsible
for all the youngsters and females

349
00:39:23,960 --> 00:39:24,960
in his harem.

350
00:39:24,960 --> 00:39:28,960
And autumn is when it's hardest
to defend them.

351
00:39:44,960 --> 00:39:48,960
To prepare for the hardship
of winter to come,

352
00:39:48,960 --> 00:39:52,960
these 400kg herbivores

353
00:39:52,960 --> 00:39:55,960
have gown an extra layer
of insulation

354
00:39:55,960 --> 00:39:58,960
beneath their long, shaggy
outer coats.

355
00:39:58,960 --> 00:40:03,960
One of the warmest natural fibres
in the world.

356
00:40:09,960 --> 00:40:12,000
But for the alpha male,

357
00:40:12,000 --> 00:40:15,960
there's a much more pressing
problem than the cold.

358
00:40:22,000 --> 00:40:24,800
Lone males

359
00:40:24,800 --> 00:40:28,960
that come here to steal his harem.

360
00:40:32,960 --> 00:40:36,960
It's the alpha's job
to fight them off.

361
00:40:40,640 --> 00:40:43,960
He sidesteps
to make himself look bigger.

362
00:40:46,960 --> 00:40:49,480
But his rival is an equal match...

363
00:40:51,960 --> 00:40:54,960
..and is not backing down.

364
00:41:06,480 --> 00:41:11,960
Running head-on towards each other
at 50kph

365
00:41:11,960 --> 00:41:14,960
is like driving towards
an oncoming car.

366
00:41:24,960 --> 00:41:26,960
If the alpha's defeated,

367
00:41:26,960 --> 00:41:29,960
he'll lose all his females.

368
00:41:32,160 --> 00:41:35,960
Ten-centimetre skulls and horns

369
00:41:35,960 --> 00:41:39,160
protect them
from fatal brain injury.

370
00:41:55,000 --> 00:41:58,480
The challenger
is finally chased off...

371
00:42:00,960 --> 00:42:03,960
..leaving the alpha free to mate

372
00:42:03,960 --> 00:42:06,960
with all the females in his harem.

373
00:42:08,960 --> 00:42:10,960
For this season, at least.

374
00:42:15,960 --> 00:42:18,960
It's now almost 12 months

375
00:42:18,960 --> 00:42:22,960
since our journey
round the sun began.

376
00:42:25,960 --> 00:42:28,960
But before the Earth
comes full circle...

377
00:42:30,000 --> 00:42:34,960
..the penguin chick
has one final challenge to overcome.

378
00:42:38,960 --> 00:42:41,960
It's time for her to leave home.

379
00:42:44,960 --> 00:42:48,960
She's now sporting
a fully-waterproof adult coat...

380
00:42:50,960 --> 00:42:54,960
..having gone through
that awkward teenage stage

381
00:42:54,960 --> 00:42:56,960
and shed her fluffy down.

382
00:43:06,480 --> 00:43:09,960
She must now swap
the safety of her island home

383
00:43:09,960 --> 00:43:12,960
for the big blue beyond.

384
00:43:19,960 --> 00:43:22,640
But her path to adulthood...

385
00:43:25,320 --> 00:43:27,960
..is full of killer whales.

386
00:43:39,960 --> 00:43:45,960
Up ahead, less cautious penguins
take the plunge.

387
00:43:50,960 --> 00:43:54,960
And their commotion
distracts the predators.

388
00:43:59,960 --> 00:44:01,960
It's her chance!

389
00:44:10,960 --> 00:44:13,960
She's almost through
the danger zone.

390
00:44:20,960 --> 00:44:22,960
But she's been spotted.

391
00:44:22,960 --> 00:44:26,960
These six-tonne killers are faster.

392
00:44:35,960 --> 00:44:38,960
But only in a straight line.

393
00:44:45,960 --> 00:44:47,960
The penguin may be young...

394
00:44:52,960 --> 00:44:55,960
...but she's already agile enough
to get away.

395
00:44:59,960 --> 00:45:03,960
Not bad for her first-ever swim.

396
00:45:09,000 --> 00:45:11,960
For the next three years,

397
00:45:11,960 --> 00:45:15,960
this ocean will be her home...

398
00:45:16,960 --> 00:45:21,960
..until she returns
to this exact same spot

399
00:45:21,960 --> 00:45:24,160
to raise a family of her own.

400
00:45:31,480 --> 00:45:34,800
Our planet has now completed

401
00:45:34,800 --> 00:45:39,960
its 940 million-kilometre orbit
around the sun.

402
00:45:41,480 --> 00:45:46,960
And the penguin has completed
her first year of life.

403
00:45:46,960 --> 00:45:51,000
But the journey doesn't end here.

404
00:45:51,000 --> 00:45:55,960
As one year draws to a close,

405
00:45:55,960 --> 00:45:59,320
the next is already beginning.

406
00:46:00,960 --> 00:46:02,960
Across the globe,

407
00:46:02,960 --> 00:46:07,960
life will continue to be shaped
by the sun's influence.

408
00:46:11,000 --> 00:46:13,960
It drives seasonal changes...

409
00:46:14,960 --> 00:46:17,960
..nurtures incredible diversity...

410
00:46:18,960 --> 00:46:20,480
..and unites us all...

411
00:46:23,960 --> 00:46:25,960
..as we journey together

412
00:46:25,960 --> 00:46:30,960
through another year
on planet Earth.

413
00:46:38,960 --> 00:46:40,960
Subtitles by accessibility@itv.com