1
00:00:10,005 --> 00:00:12,525
(HOOTING AND PIPING)

2
00:00:12,565 --> 00:00:13,645
(HONKING)

3
00:00:13,685 --> 00:00:16,765
DAVID ATTENBOROUGH: The natural
world is filled with sound.

4
00:00:16,805 --> 00:00:19,445
(CLICKING, THUNDER CRASHING)

5
00:00:19,485 --> 00:00:21,365
(CLUCKING)

6
00:00:21,405 --> 00:00:23,045
(BRAYING)

7
00:00:23,085 --> 00:00:24,205
(GROWLING)

8
00:00:25,125 --> 00:00:28,885
But, so far, we've been hearing
only part of it.

9
00:00:31,125 --> 00:00:34,365
Some animals call
even before they enter the world.

10
00:00:34,405 --> 00:00:36,885
(SQUEAKING, SOFT HONKING)

11
00:00:36,925 --> 00:00:37,965
(RATTLING SOUND)

12
00:00:40,325 --> 00:00:43,285
Others use sound to communicate
with their siblings.

13
00:00:43,325 --> 00:00:45,005
(CHATTERING)

14
00:00:48,525 --> 00:00:49,725
Or call to their parents.

15
00:00:49,765 --> 00:00:51,605
(GROUP SQUAWKING)

16
00:00:51,645 --> 00:00:55,725
Using the most advanced
audio technology,

17
00:00:55,765 --> 00:00:57,605
we can listen to them all...
(DRAWN-OUT WHINE)

18
00:00:59,285 --> 00:01:02,365
..to reveal how baby animals
use sound to stay alive...

19
00:01:02,405 --> 00:01:03,405
(WHINES)

20
00:01:04,365 --> 00:01:07,165
..in a world where the odds
are stacked against them.

21
00:01:07,205 --> 00:01:08,965
(HOWLING)

22
00:01:16,085 --> 00:01:18,365
(ANIMATED BIRDSONG)

23
00:01:20,925 --> 00:01:23,245
The most perilous time
in an animal's life

24
00:01:24,044 --> 00:01:25,965
is at its very beginning.

25
00:01:29,365 --> 00:01:30,485
(CHUCKLES)

26
00:01:32,205 --> 00:01:34,484
These little cygnets are just
three days old.

27
00:01:41,685 --> 00:01:44,845
And at this stage of their lives,
and for some months to come,

28
00:01:44,885 --> 00:01:47,044
they are unable to fly.

29
00:01:48,525 --> 00:01:53,405
As a consequence, they are easy prey
for a gull or a fox.

30
00:01:56,205 --> 00:02:00,805
But there's just one thing
that is of extreme importance

31
00:02:00,845 --> 00:02:02,205
to their survival.

32
00:02:02,245 --> 00:02:04,165
And that...is sound.

33
00:02:04,205 --> 00:02:06,285
(CHIRPING)

34
00:02:17,285 --> 00:02:20,725
The Kalahari Desert
in southern Africa.

35
00:02:22,165 --> 00:02:24,805
(CHIRRUPING)

36
00:02:24,845 --> 00:02:27,765
This is the home of a kind of
burrowing mongoose...

37
00:02:29,605 --> 00:02:30,925
Meerkats.

38
00:02:30,965 --> 00:02:33,005
(HIGH-PITCHED CHIRPING
AND GRUNTING)

39
00:02:34,565 --> 00:02:37,525
This season's pups are taking
their first steps in the world

40
00:02:37,565 --> 00:02:39,925
outside their family's home.

41
00:02:45,045 --> 00:02:46,205
(CHATTERS)

42
00:02:49,005 --> 00:02:50,925
(SHORT SCREECHES)

43
00:02:55,045 --> 00:02:57,205
(SQUAWKS)

44
00:02:59,965 --> 00:03:03,405
In time, they will get to know
the sounds of everything

45
00:03:04,485 --> 00:03:06,805
that's going on around them.

46
00:03:07,805 --> 00:03:09,165
(FLIES BUZZING)

47
00:03:09,205 --> 00:03:10,245
(SNORTS)

48
00:03:10,285 --> 00:03:14,925
But just now, what they want
is breakfast.

49
00:03:15,685 --> 00:03:17,965
And to get it,
they must make themselves heard.

50
00:03:18,005 --> 00:03:19,485
(SQUEAKS)

51
00:03:20,605 --> 00:03:23,765
The smallest pup has an injured foot

52
00:03:23,805 --> 00:03:25,805
and keeping up with the rest is
a struggle.

53
00:03:30,285 --> 00:03:31,685
(HIGH-PITCHED GRUNTS)

54
00:03:35,084 --> 00:03:38,165
Once they emerge, meerkat pups
need more food

55
00:03:38,205 --> 00:03:40,845
than their own parents
can provide,

56
00:03:40,885 --> 00:03:44,685
so they must persuade other adults
to feed them.

57
00:03:44,725 --> 00:03:46,365
(PURRS)

58
00:03:51,605 --> 00:03:54,245
But in this harsh country,

59
00:03:54,285 --> 00:03:56,965
food isn't easy to find.

60
00:03:58,565 --> 00:04:02,125
Temperatures can reach over 45C,

61
00:04:02,165 --> 00:04:04,525
and most food is hidden underground.

62
00:04:07,405 --> 00:04:11,245
So a meerkat's life is dominated
by digging.

63
00:04:12,645 --> 00:04:15,285
They may have to shift
their entire body weight in sand

64
00:04:15,325 --> 00:04:18,805
to find just one mouthful to eat.

65
00:04:21,404 --> 00:04:24,325
After all this hard work,
the helpers can be more interested

66
00:04:24,365 --> 00:04:26,205
in feeding themselves than the pups.

67
00:04:26,245 --> 00:04:28,925
(RAPID PURRING)

68
00:04:33,605 --> 00:04:37,005
So the youngsters beg continuously.

69
00:04:37,045 --> 00:04:39,765
(SQUEAKING AND PURRING)

70
00:04:44,805 --> 00:04:47,605
The moment food is found,

71
00:04:47,645 --> 00:04:50,885
each pup switches to a high-pitched
begging call

72
00:04:50,925 --> 00:04:54,285
in an attempt to ensure that it,
and not its siblings,

73
00:04:54,325 --> 00:04:55,485
gets the mouthful.

74
00:04:55,525 --> 00:04:56,805
(ALL CHATTERING AND SQUEAKING)

75
00:05:01,765 --> 00:05:04,605
And those who make this begging call
more intensely

76
00:05:04,645 --> 00:05:06,885
get the food.

77
00:05:07,805 --> 00:05:12,805
The biggest pup is successful,
and the smallest misses out again...

78
00:05:14,245 --> 00:05:15,765
..and again.

79
00:05:20,405 --> 00:05:24,085
Staying close to an adult
increases the chances of being heard

80
00:05:24,125 --> 00:05:25,565
and being fed.

81
00:05:27,805 --> 00:05:31,045
But this brings its own hazards.

82
00:05:33,205 --> 00:05:36,645
(PUP SQUEAKS)

83
00:05:38,164 --> 00:05:40,485
Finally, the small one does get
a mouthful.

84
00:05:44,325 --> 00:05:47,525
But he takes a long time
to eat it...

85
00:05:51,845 --> 00:05:55,365
..and when he looks up,
everyone else has gone.

86
00:05:55,405 --> 00:05:56,805
(SOFT SQUEAK)

87
00:06:01,525 --> 00:06:04,485
If there's one thing more important
to a meerkat than food,

88
00:06:05,445 --> 00:06:06,965
it's family.

89
00:06:08,685 --> 00:06:12,885
Without their guidance, he wouldn't
last for long in this intense heat.

90
00:06:15,965 --> 00:06:17,085
(CHIRPS)

91
00:06:17,125 --> 00:06:18,645
He calls for help.

92
00:06:18,685 --> 00:06:20,925
(CHIRPS)

93
00:06:23,725 --> 00:06:25,045
(LONG CHIRP)

94
00:06:25,085 --> 00:06:27,045
Making such a noise, however,
has risks.

95
00:06:27,085 --> 00:06:28,205
(CHIRPS)

96
00:06:34,205 --> 00:06:35,805
(DISTANT CHIRP)

97
00:06:37,325 --> 00:06:39,085
At last an adult hears him.

98
00:06:39,965 --> 00:06:41,164
(SQUEAKING)

99
00:07:00,125 --> 00:07:04,205
But the heat and exhaustion
have taken their toll.

100
00:07:05,085 --> 00:07:06,605
It may be too late.

101
00:07:08,365 --> 00:07:11,685
His sister encourages him
to get back on his feet.

102
00:07:11,725 --> 00:07:14,325
(CHEEPING)

103
00:07:28,685 --> 00:07:32,765
Once again, the little meerkat
has been saved...by sound.

104
00:07:35,565 --> 00:07:38,925
(URGENT BARKING)

105
00:07:40,445 --> 00:07:45,245
As the pups grow, they will face
many new challenges...

106
00:07:47,164 --> 00:07:49,845
..including predators.

107
00:07:51,605 --> 00:07:54,885
Sound will be invaluable to help
them navigate these dangers.

108
00:07:54,925 --> 00:07:56,925
(CROAKING)

109
00:07:58,085 --> 00:08:02,405
But some baby animals use sound
before they even enter the world.

110
00:08:03,285 --> 00:08:04,885
(BIRDS HOOT AND PIPE)

111
00:08:06,365 --> 00:08:08,085
The swamps of South America.

112
00:08:12,325 --> 00:08:13,805
There is danger everywhere.

113
00:08:13,845 --> 00:08:16,485
(SNORTING)

114
00:08:20,245 --> 00:08:23,565
One vigilant mother here is
on guard.

115
00:08:25,565 --> 00:08:26,645
A caiman.

116
00:08:28,965 --> 00:08:32,365
Over two metres long and weighing
around 60 kilograms,

117
00:08:32,405 --> 00:08:36,845
she lives by ambushing prey
in these murky waters.

118
00:08:39,205 --> 00:08:41,564
On the bank, close to the river,

119
00:08:42,285 --> 00:08:43,485
there is a great mound.

120
00:08:47,925 --> 00:08:50,245
It's her nest.

121
00:08:55,205 --> 00:08:56,845
And inside, there are her eggs,

122
00:08:58,965 --> 00:09:00,845
30 or so of them.

123
00:09:05,725 --> 00:09:10,045
Her nest-guarding duties, however,
are coming to an end.

124
00:09:13,805 --> 00:09:16,045
The young, still within the eggs,

125
00:09:16,085 --> 00:09:18,765
are approaching one of the most
dangerous moments

126
00:09:18,805 --> 00:09:20,565
they will ever face.

127
00:09:20,605 --> 00:09:22,965
And they are squeaking.

128
00:09:24,205 --> 00:09:26,525
(PULSING SQUEAKS)

129
00:09:26,565 --> 00:09:30,045
Their chances of survival
will depend on these noises.

130
00:09:32,045 --> 00:09:36,285
We have a special camera
with 60 super-sensitive microphones

131
00:09:36,325 --> 00:09:39,965
which can show us which squeak
is coming from which egg.

132
00:09:40,005 --> 00:09:41,765
(SQUEAKING)

133
00:09:41,805 --> 00:09:44,485
(SQUEAKING)

134
00:09:46,525 --> 00:09:47,925
The first starts to hatch.

135
00:09:50,085 --> 00:09:52,245
(SQUEAKING)

136
00:09:52,285 --> 00:09:56,005
But the youngsters would stand
a much better chance of survival

137
00:09:56,045 --> 00:09:58,885
if they all hatched simultaneously.

138
00:09:58,925 --> 00:10:00,085
(VARIOUS TONES OF SQUEAKING)

139
00:10:00,885 --> 00:10:02,085
So they call to one another

140
00:10:02,125 --> 00:10:05,205
to indicate how close they are
to emerging.

141
00:10:06,645 --> 00:10:09,405
(SHORT GRUNTS AND SQUEAKS)

142
00:10:12,005 --> 00:10:14,405
It succeeds in struggling free
from the egg.

143
00:10:18,405 --> 00:10:20,125
But it has a problem.

144
00:10:20,165 --> 00:10:21,725
(BIRDS CHIRPING)

145
00:10:23,405 --> 00:10:26,125
The nest that once kept them
all safe...

146
00:10:27,645 --> 00:10:29,205
..now keeps them trapped.

147
00:10:29,245 --> 00:10:31,565
(GULPING SQUEAKS AND HONKS)

148
00:10:35,165 --> 00:10:38,085
The calls of the emerged
now encourage the others

149
00:10:38,125 --> 00:10:40,645
to break out of their eggs.

150
00:10:40,685 --> 00:10:42,965
(HONKS)

151
00:10:44,605 --> 00:10:48,445
But they still can't get out of
the nest without help.

152
00:10:51,885 --> 00:10:54,325
Individually,
they can barely be heard.

153
00:10:54,365 --> 00:10:56,165
(HONKS)

154
00:10:57,325 --> 00:11:01,165
But together they become loud enough
for their mother to hear them.

155
00:11:01,205 --> 00:11:04,405
(MANY HONKING SIMULTANEOUSLY)

156
00:11:04,445 --> 00:11:06,765
(CHORUS OF HONKS)

157
00:11:06,805 --> 00:11:10,645
She has been waiting for these
sounds for nearly 70 days.

158
00:11:11,805 --> 00:11:15,285
(ANIMATED HONKING)

159
00:11:21,045 --> 00:11:22,765
(HONKING)

160
00:11:24,765 --> 00:11:26,125
And she goes into action.

161
00:11:27,885 --> 00:11:30,725
(HATCHLINGS HONK AND CHITTER)

162
00:11:57,485 --> 00:12:00,125
One by one,
she picks her hatchlings up

163
00:12:00,165 --> 00:12:02,365
and takes them down to the water.

164
00:12:19,445 --> 00:12:23,245
The last to hatch
are sometimes forgotten.

165
00:12:24,805 --> 00:12:28,685
But with the nest fully opened,
they can now get out.

166
00:12:30,605 --> 00:12:33,445
But they have no idea
where their mother is.

167
00:12:35,085 --> 00:12:38,365
(HONK AND CHITTER)
Once again, they are saved by sound.

168
00:12:42,005 --> 00:12:44,845
They can recognise the voices
of their siblings

169
00:12:44,885 --> 00:12:46,845
and follow the sound to the water...

170
00:12:46,885 --> 00:12:49,765
where their mother
will guard them all.

171
00:12:50,565 --> 00:12:52,245
(CHITTERING)

172
00:12:53,885 --> 00:12:57,805
Sound has guided them on the first
and most hazardous journey

173
00:12:57,845 --> 00:12:59,005
of their lives.

174
00:13:02,885 --> 00:13:05,365
(CHITTERING)

175
00:13:16,645 --> 00:13:17,965
(CUCKOO CALLS)

176
00:13:18,005 --> 00:13:22,005
(SHEEP BLEATS, WOODPECKER TAPS,
WOOD PIGEON COOS)

177
00:13:22,045 --> 00:13:25,525
(BLACKBIRDS SING, BEES BUZZING)

178
00:13:25,565 --> 00:13:27,365
The sounds of an English spring.

179
00:13:28,205 --> 00:13:32,045
(BIRDSONG AND BUZZING)

180
00:13:37,085 --> 00:13:39,165
For many of the animals
that live here,

181
00:13:39,965 --> 00:13:42,085
they carry important messages.

182
00:13:44,085 --> 00:13:46,125
(BEE BUZZING)

183
00:13:48,005 --> 00:13:52,085
This bee has discovered that the
flowers are now producing nectar.

184
00:13:55,565 --> 00:13:57,485
She gathers all she can...

185
00:13:59,925 --> 00:14:02,925
and then flies back
with the good news.

186
00:14:02,965 --> 00:14:04,805
(BUZZES)

187
00:14:06,845 --> 00:14:09,925
Her colony has been inactive
during the colder months.

188
00:14:11,525 --> 00:14:15,285
But now the time has come
for action.

189
00:14:15,325 --> 00:14:17,565
(HIVE BUZZES)

190
00:14:26,005 --> 00:14:27,525
(AMPLIFIED BEATING SOUND)

191
00:14:28,685 --> 00:14:31,045
The forager conveys her news

192
00:14:31,085 --> 00:14:34,445
by repeatedly thumping her abdomen
on the comb.

193
00:14:34,485 --> 00:14:41,445
Bees, like many insects,
don't have ears,

194
00:14:43,325 --> 00:14:45,925
so they can't hear airborne sounds.

195
00:14:45,965 --> 00:14:49,005
(BEATING SOUNDS)

196
00:14:49,045 --> 00:14:51,285
(BUZZING)

197
00:14:52,045 --> 00:14:56,205
But they can feel the vibrations
she makes on the comb...

198
00:14:56,245 --> 00:14:59,565
(RAPID TAPPING)

199
00:14:59,605 --> 00:15:04,805
..detecting it with the sense organs
in their legs.

200
00:15:04,845 --> 00:15:06,645
(ECHOEY TAPS)

201
00:15:11,845 --> 00:15:14,445
And those that are still asleep

202
00:15:14,485 --> 00:15:18,765
are alerted by her signal that drums
directly into their body.

203
00:15:18,805 --> 00:15:21,005
(CONSTANT TAPPING)

204
00:15:27,525 --> 00:15:31,485
Eventually, the workers are roused
into action.

205
00:15:51,885 --> 00:15:55,245
Within days,
the hive's depleted stores

206
00:15:55,285 --> 00:15:58,405
are restocked with nectar
and pollen...

207
00:15:59,685 --> 00:16:03,965
..food that will fuel the production
of the next generation of bees.

208
00:16:11,525 --> 00:16:13,845
When a colony has grown so much

209
00:16:13,885 --> 00:16:17,645
that it contains
around 40,000 individuals,

210
00:16:17,685 --> 00:16:19,885
it prepares to swarm.

211
00:16:20,925 --> 00:16:26,045
But a new swarm will need a queen,
and the old queen has already left.

212
00:16:28,045 --> 00:16:30,285
There are several contenders
for the role

213
00:16:30,325 --> 00:16:33,685
who are developing in particularly
large cells.

214
00:16:35,805 --> 00:16:38,845
Tiny super-sensitive microphones

215
00:16:38,885 --> 00:16:41,485
enable us to hear
an extraordinary call,

216
00:16:41,525 --> 00:16:42,805
like the quacking of a duck.

217
00:16:42,845 --> 00:16:44,485
(REPEATED QUACKS)

218
00:16:50,725 --> 00:16:53,405
The unhatched queens are signalling

219
00:16:53,445 --> 00:16:55,485
that they're ready to emerge.

220
00:16:55,525 --> 00:16:56,845
(QUACK-LIKE CHORUS)

221
00:16:57,965 --> 00:17:01,205
The workers detect the vibrations
of these calls

222
00:17:01,245 --> 00:17:05,965
and in response they start
to release the first queen.

223
00:17:06,005 --> 00:17:07,084
(QUACKING)

224
00:17:11,205 --> 00:17:13,965
If two queens are released
at the same time,

225
00:17:14,005 --> 00:17:16,925
they will fight one another
to the death.

226
00:17:18,165 --> 00:17:20,645
So, she does her best to make sure

227
00:17:20,685 --> 00:17:23,685
that her rivals remain
in their cells.

228
00:17:24,805 --> 00:17:26,565
(WHINING SOUND)

229
00:17:26,604 --> 00:17:31,285
She does that by making a sound
beekeepers call a toot.

230
00:17:31,325 --> 00:17:33,485
(WHINY TOOT)

231
00:17:34,525 --> 00:17:35,685
(DEEPER HUM)

232
00:17:35,725 --> 00:17:37,645
Slowed down a thousand times

233
00:17:37,685 --> 00:17:41,485
and using new software that converts
vibration to colour,

234
00:17:41,525 --> 00:17:44,645
we can see
how she creates this call.

235
00:17:44,685 --> 00:17:46,885
(HUM)

236
00:17:50,965 --> 00:17:53,285
The vibrations travel down her legs,

237
00:17:53,325 --> 00:17:57,005
across the comb, and are detected
by the legs of the workers.

238
00:18:00,885 --> 00:18:04,165
(TOOTING)

239
00:18:04,205 --> 00:18:08,325
As she toots, the whole colony,
for a few seconds,

240
00:18:08,365 --> 00:18:12,925
stops moving...
(RUSTLING STOPS)

241
00:18:12,965 --> 00:18:16,765
..in recognition that a new queen
has ascended the throne.

242
00:18:18,725 --> 00:18:22,525
Each toot
is answered by a chorus of quacks

243
00:18:22,565 --> 00:18:25,605
from the rival queens
who are still within their cells

244
00:18:25,645 --> 00:18:27,565
and eager to emerge.

245
00:18:28,685 --> 00:18:31,925
But as long as the new queen
continues tooting,

246
00:18:31,965 --> 00:18:34,445
the workers will not release
her rivals.

247
00:18:37,125 --> 00:18:40,885
The crowned queen toots
repeatedly until, after a few days,

248
00:18:40,925 --> 00:18:44,765
she prepares to depart with half
of the workers in a swarm.

249
00:18:44,805 --> 00:18:46,845
(HUGE SQUEAKS AND RUSTLING)

250
00:18:47,805 --> 00:18:50,405
The sounds in the hive become
increasingly intense,

251
00:18:50,445 --> 00:18:54,045
until finally the swarm leaves
the nest.

252
00:18:55,645 --> 00:18:58,165
(UPLIFTING MUSIC)

253
00:19:05,685 --> 00:19:08,365
They re-assemble
on a nearby branch...

254
00:19:11,645 --> 00:19:14,925
..and a new colony
will soon be established.

255
00:19:22,605 --> 00:19:24,405
(CHORUS OF CROAKS AND HONKS)

256
00:19:28,765 --> 00:19:30,365
Many animals,
when they first appear,

257
00:19:30,405 --> 00:19:33,925
rely on their parents
for everything they need

258
00:19:33,965 --> 00:19:36,245
and use sound to keep in touch
with them.

259
00:19:36,285 --> 00:19:40,005
(CROAKING AND HONKING)

260
00:19:42,685 --> 00:19:48,165
20,00 flamingos breeding
off the Yucatan coast in Mexico.

261
00:19:51,085 --> 00:19:53,405
The noise here is deafening.

262
00:19:53,445 --> 00:19:55,805
(CHORUS OF GRUNTS AND HONKS)

263
00:19:57,045 --> 00:20:01,245
The chicks, nonetheless, are able
to exchange intimate sounds

264
00:20:01,285 --> 00:20:02,445
with their parents.

265
00:20:11,445 --> 00:20:14,205
(CROAKS)

266
00:20:14,245 --> 00:20:16,725
This one has only just hatched.

267
00:20:19,565 --> 00:20:23,045
The colony provides protection
for its members.

268
00:20:23,085 --> 00:20:29,005
But living in such a huge crowd
is nonetheless hazardous.

269
00:20:29,045 --> 00:20:32,485
the chick's very survival depends on
its ability

270
00:20:32,525 --> 00:20:35,845
to recognise the voices
of its parents.

271
00:20:38,245 --> 00:20:41,365
So it must learn to do so quickly,

272
00:20:41,405 --> 00:20:42,925
because within ten days of hatching,

273
00:20:42,965 --> 00:20:45,725
it and its parents will leave
the nest.

274
00:20:45,765 --> 00:20:46,925
(CROAKS, CHICK CHIRRUPS)

275
00:20:48,325 --> 00:20:51,525
The call of each flamingo is unique.

276
00:20:53,045 --> 00:20:55,445
It's a kind of vocal fingerprint.

277
00:20:55,485 --> 00:20:58,205
(CROAKS)
How the chick manages in such a din

278
00:20:58,245 --> 00:21:03,285
to memorise and pick out the calls
of its parents is unimaginable.

279
00:21:03,325 --> 00:21:05,285
But it does so.

280
00:21:05,325 --> 00:21:07,005
(CROAKS)

281
00:21:07,045 --> 00:21:09,965
(CHIRRUPING)

282
00:21:13,405 --> 00:21:14,725
(HONKING)

283
00:21:14,765 --> 00:21:16,925
(SOFT MUSIC)

284
00:21:23,165 --> 00:21:27,085
This one is taking its first steps
out of the nest.

285
00:21:29,685 --> 00:21:33,205
But it's not really ready
for the wider world.

286
00:21:38,525 --> 00:21:40,965
Eventually it becomes
a little braver.

287
00:21:42,325 --> 00:21:44,765
but now it has a new problem.

288
00:21:45,925 --> 00:21:49,965
It's growing fast and both it
and its parents need food.

289
00:21:51,845 --> 00:21:56,005
To get it, the adults must leave
the colony and their chick.

290
00:21:57,845 --> 00:22:00,565
The chick cannot fly and will be
unable to do so

291
00:22:00,605 --> 00:22:02,165
for another three months.

292
00:22:02,205 --> 00:22:05,725
So, until then,
it's very vulnerable.

293
00:22:07,845 --> 00:22:12,485
There are hundreds of youngsters
with the same problem.

294
00:22:12,525 --> 00:22:16,885
The young gather together
in an enormous creche.

295
00:22:18,245 --> 00:22:20,045
There's safety in numbers.

296
00:22:24,445 --> 00:22:28,085
A few adults have stayed behind
to keep the creche together.

297
00:22:31,605 --> 00:22:34,045
The others eventually return.

298
00:22:35,605 --> 00:22:39,125
But now each must recognise
its own chick

299
00:22:39,165 --> 00:22:41,885
among the densely packed flock
of thousands.

300
00:22:41,925 --> 00:22:44,605
(CACOPHONY OF CLUCKING
AND CHITTERING)

301
00:22:50,845 --> 00:22:53,805
Amazingly, each family trio —
male, female and chick —

302
00:22:55,645 --> 00:22:58,245
are able to recognise
one another's voices.

303
00:23:01,085 --> 00:23:02,085
(CROAKING)

304
00:23:03,765 --> 00:23:07,085
Distinguishing individual calls
among this deafening chorus

305
00:23:07,125 --> 00:23:08,285
must be difficult.

306
00:23:10,085 --> 00:23:12,725
And this male can't find his chick.

307
00:23:12,765 --> 00:23:13,925
(CROAKING)

308
00:23:15,485 --> 00:23:18,845
Adults aren't the only ones
who are searching.

309
00:23:22,525 --> 00:23:25,085
A crocodile is lurking nearby.

310
00:23:29,125 --> 00:23:30,845
(CALLS) The chick calls...

311
00:23:30,885 --> 00:23:32,245
(CROAKS)

312
00:23:32,285 --> 00:23:34,805
But it can't hear
its father's reply.

313
00:23:39,725 --> 00:23:42,165
The crocodile attacks.

314
00:23:45,085 --> 00:23:47,405
(ANXIOUS CHITTER)

315
00:23:59,565 --> 00:24:01,965
(HUGE CHORUS OF CALLS AND CROAKS)

316
00:24:08,805 --> 00:24:10,685
It's failed to grab a chick,

317
00:24:10,725 --> 00:24:14,885
but it did create dangerous
confusion in the flock.

318
00:24:17,245 --> 00:24:19,485
The chick has become separated
from the others

319
00:24:19,525 --> 00:24:21,685
and seems to be lost.

320
00:24:21,725 --> 00:24:23,525
(CHITTERS)

321
00:24:27,445 --> 00:24:30,565
It begs for food from any individual
that passes.

322
00:24:30,605 --> 00:24:32,405
(CHITTERS)

323
00:24:36,765 --> 00:24:40,205
Its father, in another part of
the flock, keeps calling.

324
00:24:40,245 --> 00:24:42,245
(CROAKS)

325
00:24:43,445 --> 00:24:46,365
But the chick is too far away
to hear him.

326
00:24:50,765 --> 00:24:54,245
And this is how many chicks
meet their end.

327
00:24:58,525 --> 00:25:00,285
But not this one.

328
00:25:07,405 --> 00:25:09,405
(HIGH-PITCHED CHIRRUP)
It keeps calling.

329
00:25:11,965 --> 00:25:14,445
And from across the lagoon...
(CROAKS)

330
00:25:14,485 --> 00:25:15,565
..its father replies.

331
00:25:17,525 --> 00:25:20,965
(CHITTERING AND CROAKING)

332
00:25:21,005 --> 00:25:23,725
The unique sound of the chick's
voice has been recognised

333
00:25:23,765 --> 00:25:28,205
by its father, and the two at last
are re-united.

334
00:25:36,485 --> 00:25:38,485
As young animals grow,

335
00:25:38,525 --> 00:25:42,605
they learn to recognise oncoming
dangers and become big enough

336
00:25:42,645 --> 00:25:45,365
for their voices to sound an alarm.

337
00:25:55,165 --> 00:25:57,005
(CHORUS OF HOWLS)

338
00:25:59,885 --> 00:26:01,605
A wolf pack, in Ontario, Canada.

339
00:26:05,405 --> 00:26:08,285
(EERIE HOWLING)

340
00:26:09,325 --> 00:26:12,765
This communal howl binds the pack
together

341
00:26:12,805 --> 00:26:15,485
and registers their ownership
of a territory.

342
00:26:15,525 --> 00:26:18,565
(WOLVES HOWLING)

343
00:26:22,085 --> 00:26:25,725
With only around 500
of these Eastern wolves left,

344
00:26:25,765 --> 00:26:29,245
this heart-stopping sound is now
extremely rare.

345
00:26:29,285 --> 00:26:30,885
(ALL HOWLING)

346
00:26:32,005 --> 00:26:35,405
But this chorus has some new voices.

347
00:26:35,445 --> 00:26:38,045
(HOWLING AND BARKING)

348
00:26:38,085 --> 00:26:41,365
It's August and the pups
are joining in.

349
00:26:43,445 --> 00:26:46,085
These youngsters, however,
create a problem...

350
00:26:46,925 --> 00:26:49,245
..one that could endanger them all.

351
00:26:50,085 --> 00:26:52,365
(BIRDSONG)

352
00:26:57,685 --> 00:26:59,605
(DRONE OF BUZZING)

353
00:27:00,525 --> 00:27:02,485
(CHIRPS)

354
00:27:02,525 --> 00:27:05,205
Now, in summer,
the days are over 14 hours long.

355
00:27:08,525 --> 00:27:11,405
So the wolves have to hunt
in the light.

356
00:27:14,405 --> 00:27:16,525
(WHINES)

357
00:27:18,085 --> 00:27:21,085
The pups are too big
to stay in the den,

358
00:27:21,125 --> 00:27:25,485
but too inexperienced to join in
the hunt.

359
00:27:25,525 --> 00:27:31,285
So the adults leave them
in an open area - a rendezvous site.

360
00:27:32,085 --> 00:27:36,765
Its very openness makes
it a great place for play.

361
00:27:36,805 --> 00:27:40,325
But this is a particularly dangerous
time in their lives.

362
00:27:41,245 --> 00:27:44,725
Half of them won't live beyond
their first year.

363
00:27:46,125 --> 00:27:50,405
What happens here and now will
determine whether these will do so.

364
00:27:58,045 --> 00:28:02,125
Two of the youngsters know exactly
where they are supposed to stay.

365
00:28:02,165 --> 00:28:05,645
But their sister can't resist
exploring.

366
00:28:21,285 --> 00:28:22,685
(HIGH-PITCHED TWEET)

367
00:28:25,725 --> 00:28:29,885
Distracted, she doesn't notice that
a black bear is approaching.

368
00:28:33,285 --> 00:28:37,725
This is one of the few animals
that will kill a wolf pup.

369
00:28:39,885 --> 00:28:43,245
The wandering youngster seems
unaware of the danger.

370
00:28:45,645 --> 00:28:47,365
But her brothers are.

371
00:28:50,645 --> 00:28:53,085
(DISTANT HOWLING)

372
00:28:53,125 --> 00:28:54,965
They sound the alarm.
(BOTH HOWL)

373
00:28:57,525 --> 00:29:01,445
Alerted, the wandering pup spots
the bear.

374
00:29:03,645 --> 00:29:04,725
(HOWLING)

375
00:29:10,325 --> 00:29:11,445
(BARKS)

376
00:29:16,565 --> 00:29:18,845
(BARKING AND HOWLING)

377
00:29:18,885 --> 00:29:22,645
Now the lives of all three pups
are at risk.

378
00:29:25,245 --> 00:29:28,765
But, as the bear moves in,
she hears a different call.

379
00:29:32,125 --> 00:29:33,565
It's her own cub.

380
00:29:33,605 --> 00:29:35,245
And he needs his mother.

381
00:29:35,285 --> 00:29:36,325
(GROANS)

382
00:29:38,685 --> 00:29:41,205
(GROANS)

383
00:29:41,245 --> 00:29:42,565
(HOWLS)

384
00:29:42,605 --> 00:29:44,965
It's been a lucky escape
for the pups...

385
00:29:45,005 --> 00:29:46,005
(HOWLING)

386
00:29:46,805 --> 00:29:49,165
..but they are not yet
in the clear.

387
00:29:51,365 --> 00:29:53,165
The pups' howls are shorter
and higher-pitched

388
00:29:53,205 --> 00:29:55,285
than those of the adults...

389
00:29:57,525 --> 00:30:00,605
..but they can still be heard
many miles away.

390
00:30:03,125 --> 00:30:06,845
(DEEPER HOWL)
And they are answered.

391
00:30:08,285 --> 00:30:10,045
(HOWLS)

392
00:30:14,245 --> 00:30:17,085
The sound has alerted an adult wolf.

393
00:30:20,525 --> 00:30:22,805
(PURPOSEFUL MUSIC)

394
00:30:24,925 --> 00:30:27,045
(HOWLS)

395
00:30:28,765 --> 00:30:29,805
It's their father.

396
00:30:31,045 --> 00:30:32,365
(PUPS WHIMPER)

397
00:30:32,405 --> 00:30:34,405
He's returned with food
for the pups.

398
00:30:35,445 --> 00:30:37,125
(EXCITED YELPS)

399
00:30:40,205 --> 00:30:45,525
As dusk falls, the pack celebrates
with a reunion chorus.

400
00:30:45,565 --> 00:30:48,245
(DISTANT CHORUS OF HOWLS)

401
00:30:49,405 --> 00:30:52,965
Their voices have been crucial
in keeping the pack together.

402
00:30:53,005 --> 00:30:55,565
(DISTANT EERIE HOWLS)

403
00:30:55,605 --> 00:30:58,245
But many animals issue
warning calls

404
00:30:58,285 --> 00:31:01,165
that contain
far more complex information.

405
00:31:01,205 --> 00:31:02,965
(WHIMPERING)

406
00:31:05,765 --> 00:31:09,525
The meerkats, as they grow,
learn how to find their own meals.

407
00:31:12,165 --> 00:31:15,125
And they are discovering how
to avoid becoming someone else's.

408
00:31:17,405 --> 00:31:20,405
The desert is full of
hungry mouths...

409
00:31:21,845 --> 00:31:25,605
..and meerkats are small
and obviously edible.

410
00:31:28,685 --> 00:31:31,485
Their defence is neither armour
nor weapon.

411
00:31:33,845 --> 00:31:36,365
Instead, they use sound -

412
00:31:36,405 --> 00:31:38,205
a complicated system of alarms.

413
00:31:41,605 --> 00:31:44,685
These calls are not just
generalised alerts.

414
00:31:44,725 --> 00:31:47,365
(SHORT WHOOPS)

415
00:31:50,125 --> 00:31:52,325
This one warns of
a flying predator...

416
00:31:53,805 --> 00:31:55,285
(SHORT WHOOPS CONTINUE)

417
00:31:55,325 --> 00:31:58,045
..and those hearing it look up
and scan the sky.

418
00:31:58,085 --> 00:31:59,085
(WHOOPING)

419
00:32:06,765 --> 00:32:10,485
Danger on the ground is indicated
by a different call.

420
00:32:10,525 --> 00:32:12,925
(HIGHER-PITCHED HOOTS)

421
00:32:14,005 --> 00:32:15,365
Best to look around.

422
00:32:17,645 --> 00:32:19,405
(GRUNTING)

423
00:32:21,645 --> 00:32:25,965
Snakes are identified by
a third signal.

424
00:32:28,325 --> 00:32:31,885
(GRUNTS)

425
00:32:31,925 --> 00:32:34,245
A call from the look-out
summons others

426
00:32:34,285 --> 00:32:36,325
to come and help drive it away.

427
00:32:36,365 --> 00:32:38,365
(COBRA HISSES, MEERKATS GROWL)

428
00:32:45,125 --> 00:32:47,565
Meerkat warnings are so detailed

429
00:32:47,605 --> 00:32:50,045
that they can be a bit confusing
for youngsters.

430
00:32:54,085 --> 00:32:57,325
So the best thing is to do
what everybody else is doing.

431
00:32:58,205 --> 00:32:59,645
(SQUEAKS)

432
00:33:01,925 --> 00:33:04,365
The calls also carry
other information,

433
00:33:04,405 --> 00:33:07,685
such as how fast a predator
is approaching.

434
00:33:09,165 --> 00:33:12,485
And there is one call
which should never be ignored.

435
00:33:12,525 --> 00:33:14,045
(SHORT GRUNTS)

436
00:33:14,085 --> 00:33:19,525
This is the high-urgency call,
a warning of immediate danger.

437
00:33:19,565 --> 00:33:23,405
(SERIES OF SHORT GRUNTS)

438
00:33:23,445 --> 00:33:26,125
Not to react to this
could be disastrous.

439
00:33:29,645 --> 00:33:33,605
So when you hear this call...
(GRUNTING)

440
00:33:33,645 --> 00:33:35,165
..run for your life!

441
00:33:42,885 --> 00:33:44,925
(GRUNTS)

442
00:33:44,965 --> 00:33:46,965
(BIRDSONG AND CACKLING)

443
00:33:49,525 --> 00:33:53,125
Sounds in the open air are important
for many animals.

444
00:33:54,885 --> 00:33:58,725
But there is another world of sound
with which we are far less familiar.

445
00:33:59,885 --> 00:34:03,045
We can't hear very well underwater,

446
00:34:03,085 --> 00:34:06,725
because our ears are shaped
to work in the air.

447
00:34:07,485 --> 00:34:11,485
But there is a way in which we can
eavesdrop on this underwater world,

448
00:34:11,525 --> 00:34:14,885
by using a special kind of
underwater microphone

449
00:34:14,925 --> 00:34:17,445
called a hydrophone.

450
00:34:21,405 --> 00:34:24,765
(PULSING CHIRP-LIKE SOUNDS)

451
00:34:24,805 --> 00:34:28,164
I don't know exactly what's making
those noises,

452
00:34:28,204 --> 00:34:32,485
it's probably some small
invertebrates or maybe a small fish.

453
00:34:32,525 --> 00:34:36,445
We've known for some time that
quite a lot of fish produce sounds.

454
00:34:37,445 --> 00:34:40,485
It's only recently, however,
that scientists have discovered

455
00:34:40,525 --> 00:34:43,644
just how widespread that ability is.

456
00:34:54,445 --> 00:34:59,885
The ocean covers around 70% of
our planet's surface.

457
00:35:06,165 --> 00:35:08,285
And sound also plays a crucial role

458
00:35:08,325 --> 00:35:12,285
in the lives of many of the animals
that live in it.

459
00:35:12,325 --> 00:35:14,285
(CROAKING AND CREAKING SOUNDS)

460
00:35:17,805 --> 00:35:20,205
Coral reefs are surprisingly
noisy places.

461
00:35:21,325 --> 00:35:22,405
(DEEP CROAKS)

462
00:35:23,965 --> 00:35:25,965
Many of these sounds are made
by fish.

463
00:35:27,485 --> 00:35:30,845
(GRUNTING AND CROAKING)

464
00:35:40,405 --> 00:35:42,925
Here too, sound can be important

465
00:35:42,965 --> 00:35:45,685
from the very beginning of
an animal's life.

466
00:35:47,325 --> 00:35:51,845
Without it, one of the most
strikingly coloured fish on the reef

467
00:35:51,885 --> 00:35:54,205
would never find its way home.

468
00:35:58,445 --> 00:36:00,845
It's just days before a full moon

469
00:36:00,885 --> 00:36:04,565
and this female clownfish is about
to lay her eggs.

470
00:36:10,205 --> 00:36:12,285
Clownfish live in small communities,

471
00:36:13,525 --> 00:36:18,285
each based around a particularly
large anemone.

472
00:36:23,765 --> 00:36:28,485
In this busy colony,
only two adults will reproduce -

473
00:36:28,525 --> 00:36:31,205
the largest, the dominant female...

474
00:36:32,125 --> 00:36:35,685
..and her partner, the next in size,
the dominant male.

475
00:36:37,565 --> 00:36:40,805
There's a strict hierarchy,
one that's based on size,

476
00:36:40,845 --> 00:36:43,285
but policed by sound.

477
00:36:44,925 --> 00:36:46,125
(CROAKY GRUNTS)

478
00:36:46,165 --> 00:36:50,285
Her larger body enables her
to make the deepest sound

479
00:36:50,325 --> 00:36:54,565
by snapping her teeth together
to produce pops and pulses.

480
00:36:54,605 --> 00:36:57,445
(PULSING GRUNTS)

481
00:37:02,325 --> 00:37:04,965
(SHORT GRUNTS)

482
00:37:07,165 --> 00:37:10,005
The male signals
his subordinate status

483
00:37:10,045 --> 00:37:12,125
by quivering his head

484
00:37:12,165 --> 00:37:14,365
and producing a purring noise.

485
00:37:16,805 --> 00:37:20,845
And everyone around the anemone
knows that she is the boss.

486
00:37:25,845 --> 00:37:28,965
At full moon, she will be ready
to lay eggs.

487
00:37:31,445 --> 00:37:34,485
So the group needs to find
a firm surface for them.

488
00:37:36,685 --> 00:37:39,005
A coconut shell, brought in
by the currents,

489
00:37:39,045 --> 00:37:41,085
would be ideal.

490
00:37:43,485 --> 00:37:45,765
But it needs to be moved
into the right position.

491
00:37:47,805 --> 00:37:50,565
She indicates her needs
with a low-pitched grunt,

492
00:37:50,605 --> 00:37:55,325
and the juveniles in the colony
comply by shaking their heads.

493
00:38:03,005 --> 00:38:04,965
(MYSTERIOUS MUSIC)

494
00:38:05,005 --> 00:38:09,325
Working together, they manoeuvre
the coconut shell into position.

495
00:38:12,045 --> 00:38:15,365
Team work takes a lot of
co-ordination,

496
00:38:15,405 --> 00:38:18,205
and a lot of grunting
and jaw-grinding.

497
00:38:25,965 --> 00:38:30,125
Next, the stage needs
to be prepared.

498
00:38:36,365 --> 00:38:38,085
And at last, the moment arrives.

499
00:38:44,685 --> 00:38:48,045
She lays her eggs in neat lines.

500
00:39:02,925 --> 00:39:07,405
The male then makes HIS contribution
- fertilising the eggs.

501
00:39:14,445 --> 00:39:16,005
Now he takes charge.

502
00:39:20,245 --> 00:39:24,085
For the next seven days, he will fan
and clean the eggs as they develop.

503
00:39:34,165 --> 00:39:37,485
Three more days and the embryos
begin to respond

504
00:39:37,525 --> 00:39:39,805
to the sounds around them.

505
00:39:39,845 --> 00:39:41,765
(GRUNTING)

506
00:39:41,805 --> 00:39:45,965
The sounds that they hear now
could play a critical role

507
00:39:46,005 --> 00:39:48,405
in the next stage of their lives.

508
00:39:53,685 --> 00:39:58,205
But a different sort of noise is
already threatening their survival.

509
00:40:04,485 --> 00:40:07,845
The male reacts to the noise of
a boat as he would to a predator.

510
00:40:12,885 --> 00:40:14,805
If there is constant motor traffic,

511
00:40:14,845 --> 00:40:18,845
he spends more time hiding
and less tending the eggs...

512
00:40:18,885 --> 00:40:21,325
so they are more vulnerable
to predators and disease.

513
00:40:21,365 --> 00:40:24,725
(THRUM OF MOTOR BOAT)

514
00:40:25,925 --> 00:40:29,285
The noise around these reefs
has increased dramatically

515
00:40:29,325 --> 00:40:33,845
in recent decades, and that has
affected the lives of the fish here.

516
00:40:36,565 --> 00:40:40,245
But the clownfish father has managed
to keep his young healthy,

517
00:40:40,285 --> 00:40:43,165
and a week later,
they begin to change.

518
00:40:46,285 --> 00:40:49,245
The plankton-sized fry wriggle free

519
00:40:49,285 --> 00:40:53,045
and are then swept away from
the reef by ocean currents.

520
00:40:53,085 --> 00:40:55,485
(UPLIFTING CELLO MUSIC)

521
00:41:03,765 --> 00:41:08,685
For ten days, the larval fish drift
out in the open ocean.

522
00:41:14,645 --> 00:41:16,245
(BIRDS CRY)

523
00:41:20,205 --> 00:41:24,125
By the time that each is about
the size of a grain of rice,

524
00:41:24,165 --> 00:41:27,765
they are strong enough to swim
against the current.

525
00:41:28,965 --> 00:41:32,245
And they need to find their way
back to a reef.

526
00:41:40,205 --> 00:41:43,565
The key to their homecoming
is sound.

527
00:41:45,725 --> 00:41:50,645
Underwater, the sounds of a reef
can be heard for many miles around.

528
00:41:50,685 --> 00:41:55,285
The tiny young clownfish can hear
this noise and swim towards it.

529
00:41:58,725 --> 00:42:02,085
They can even judge the health of
a reef by its sound.

530
00:42:02,125 --> 00:42:05,485
The noisier it is,
the more vigorous it is.

531
00:42:05,525 --> 00:42:07,525
(CLACKING AND BUBBLING)

532
00:42:26,165 --> 00:42:29,885
The anemone will provide him with
shelter and sanctuary

533
00:42:29,925 --> 00:42:33,645
for the rest of his life.

534
00:42:33,685 --> 00:42:36,325
Sound has brought him home.

535
00:42:36,365 --> 00:42:38,285
(UPLIFTING MUSIC)

536
00:42:40,925 --> 00:42:44,445
For these fish, and for many other
baby animals,

537
00:42:44,485 --> 00:42:48,925
sound is crucial for launching
themselves into the world

538
00:42:48,965 --> 00:42:53,485
and learning what they need to stay
safe and to thrive.

539
00:42:54,565 --> 00:42:58,045
For them, sound is survival.

540
00:43:04,965 --> 00:43:07,445
(GENTLE MUSIC)

541
00:43:22,645 --> 00:43:24,725
What's one of the close ones
over here...

542
00:43:24,765 --> 00:43:28,525
Biologist Mark Meekan
became fascinated by coral reefs

543
00:43:28,565 --> 00:43:29,845
more than 30 years ago.

544
00:43:31,045 --> 00:43:33,525
'Coral reefs are these incredible
habitats

545
00:43:33,565 --> 00:43:37,365
and I've always been struck by
their diversity

546
00:43:37,405 --> 00:43:39,725
and just incredible beauty.'

547
00:43:39,765 --> 00:43:43,485
Today he is fighting to save
these reefs

548
00:43:43,525 --> 00:43:46,125
from the ravages of climate change.

549
00:43:46,165 --> 00:43:49,805
This is Australia's Ningaloo Reef

550
00:43:49,845 --> 00:43:52,525
that stretches along the country's
western coast.

551
00:43:54,485 --> 00:43:55,765
But over decades of research,

552
00:43:55,805 --> 00:43:58,445
Mark discovered something else —

553
00:43:58,485 --> 00:44:01,725
that coral reefs are full of sound.

554
00:44:04,165 --> 00:44:06,485
A hunch about the significance
of this inspired him

555
00:44:06,525 --> 00:44:11,405
to try and find a way to use
this sound to save coral reefs.

556
00:44:13,005 --> 00:44:14,845
'If we could hear underwater,

557
00:44:14,885 --> 00:44:18,645
we would hear this cacophony of
hoots and yowls,

558
00:44:18,685 --> 00:44:21,445
really strange screams made by fish.

559
00:44:22,605 --> 00:44:26,125
And these little fish may actually
be helping the coral to grow.

560
00:44:26,165 --> 00:44:31,725
Basically, by sheltering in
the coral, pooping in the coral,

561
00:44:31,765 --> 00:44:33,125
fertilising the coral.

562
00:44:35,045 --> 00:44:38,765
A healthy reef is really
very noisy.'

563
00:44:38,805 --> 00:44:41,085
This sound is key.

564
00:44:41,125 --> 00:44:44,965
After hatching, reef fish are swept
out to sea.

565
00:44:45,005 --> 00:44:48,965
When they return,
they use these healthy sounds

566
00:44:49,005 --> 00:44:51,685
to choose the reef
that will be their home.

567
00:44:51,725 --> 00:44:54,045
And this was just a wow moment.

568
00:44:54,085 --> 00:44:57,925
We suddenly thought, "We can
actually use this to help the reef."

569
00:45:00,485 --> 00:45:05,285
The result is a multi-million-dollar
project with one goal —

570
00:45:05,325 --> 00:45:10,325
to discover if sound can also help
save a dying reef.

571
00:45:16,005 --> 00:45:20,525
The first step is to collect three
and a half tons of coral debris.

572
00:45:22,445 --> 00:45:24,845
It's alive and extremely vulnerable.

573
00:45:28,925 --> 00:45:31,325
Mark's team build
60 experimental reefs.

574
00:45:34,285 --> 00:45:38,445
Underwater speakers are guided
to some of these and turned on.

575
00:45:41,125 --> 00:45:43,405
It's their job to attract fish

576
00:45:43,445 --> 00:45:46,165
by playing the sounds of
a healthy reef.

577
00:45:47,325 --> 00:45:51,285
The results will be compared
to experimental reefs

578
00:45:51,325 --> 00:45:53,245
without speakers.

579
00:45:57,885 --> 00:46:00,965
At Ningaloo, it's a new moon.

580
00:46:03,765 --> 00:46:06,445
Tonight,
the reef fish are coming home.

581
00:46:08,325 --> 00:46:09,885
(BUBBLING AND POPPING SOUNDS)

582
00:46:09,925 --> 00:46:13,405
At the experimental sites,
speakers are on,

583
00:46:13,445 --> 00:46:17,125
broadcasting the sounds of
a healthy reef.

584
00:46:19,285 --> 00:46:20,965
OK, get ready, Daphne.

585
00:46:21,005 --> 00:46:23,445
They are laying out light traps

586
00:46:23,485 --> 00:46:26,685
and assessing if the speakers are
attracting fish

587
00:46:26,725 --> 00:46:30,285
to the experimental reefs with sound

588
00:46:30,325 --> 00:46:32,405
versus ones without.

589
00:46:33,365 --> 00:46:34,685
And they are!

590
00:46:34,725 --> 00:46:36,805
'We actually got the fish to come.

591
00:46:38,285 --> 00:46:41,485
They arrived in big numbers
on the reefs.'

592
00:46:45,445 --> 00:46:50,365
Mark's team have been photographing
these reefs for 12 months.

593
00:46:54,805 --> 00:46:57,765
Now they're going to see if the fish
have helped the coral to grow again.

594
00:47:01,245 --> 00:47:05,565
So, on the left here, we've got our
patch reef model from one year ago.

595
00:47:05,605 --> 00:47:09,365
And on the right-hand side, our reef
model from a couple of days ago.

596
00:47:09,405 --> 00:47:13,405
You can see fairly obviously
already

597
00:47:13,445 --> 00:47:16,205
there's been a fair bit of growth
over the year.

598
00:47:18,525 --> 00:47:22,245
Wow!
This one's roughly 20cm across,

599
00:47:22,285 --> 00:47:23,645
maximum diameter,

600
00:47:23,685 --> 00:47:26,005
and the same colony a year later,
it's almost 40.

601
00:47:26,045 --> 00:47:30,045
So we've doubled in size.
Fantastic, man.

602
00:47:31,445 --> 00:47:32,685
(LAUGHS)

603
00:47:32,725 --> 00:47:34,405
Wow.

604
00:47:34,445 --> 00:47:35,805
(SOUNDS OF PIPS AND POPS)

605
00:47:37,805 --> 00:47:40,005
oral reefs today are in such a state

606
00:47:40,045 --> 00:47:43,645
that we're beyond shouting
to everybody that it's bad.

607
00:47:43,685 --> 00:47:47,245
We have to move into doing something
about it.

608
00:47:50,525 --> 00:47:54,565
The sound made by fish might just be
a vital tool

609
00:47:54,605 --> 00:47:58,645
to help scientists save coral reefs
around the globe.

610
00:48:03,605 --> 00:48:06,645
(SPRINGTIME BIRDSONG)

611
00:48:09,125 --> 00:48:11,405
(CUCKOO CALLS)

612
00:48:13,725 --> 00:48:16,245
(BLACKBIRD SINGS)

613
00:48:17,925 --> 00:48:20,685
(SHEEP BLEATS)

614
00:48:25,805 --> 00:48:27,565
(WOOD PIGEON COOING)

615
00:48:33,605 --> 00:48:36,045
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