1
00:00:10,005 --> 00:00:13,285
(CHIRRUPING AND ANIMAL CALLS)

2
00:00:13,325 --> 00:00:15,645
(SQUAWKING AND CHIRPING)

3
00:00:15,685 --> 00:00:19,165
DAVID ATTENBOROUGH: The natural world
is filled with sound.

4
00:00:19,205 --> 00:00:21,285
(THUNDERCLAP)

5
00:00:21,325 --> 00:00:23,205
(CLUCKING)

6
00:00:23,245 --> 00:00:25,205
(BELLOWS AND SCREECHES)

7
00:00:25,245 --> 00:00:27,245
(ROARS HOARSELY)

8
00:00:27,285 --> 00:00:31,285
But so far,
we've been hearing only part of it.

9
00:00:31,325 --> 00:00:32,525
(CHIRRUPS AND CLICKS)

10
00:00:32,565 --> 00:00:33,845
(PULSATING SQUEAKS)

11
00:00:33,885 --> 00:00:36,365
The most advanced audio technology

12
00:00:36,405 --> 00:00:39,805
can now record sounds
that we can't even hear.

13
00:00:39,845 --> 00:00:41,205
(DEEP VIBRATING HUM)

14
00:00:41,245 --> 00:00:43,005
(RATTLING)

15
00:00:43,045 --> 00:00:47,085
(WHOOPING CALL)

16
00:00:47,125 --> 00:00:49,605
(SOFT CLICKING)

17
00:00:49,645 --> 00:00:51,445
(CHIRPS)

18
00:00:52,365 --> 00:00:55,885
For some animals,
sound is the key to survival.

19
00:00:55,925 --> 00:00:57,045
(BUZZING)

20
00:00:57,085 --> 00:00:58,285
(CLICKS AND SQUEAKS)

21
00:00:59,205 --> 00:01:01,325
They use sound to hunt...

22
00:01:01,365 --> 00:01:03,365
(FRANTIC SCREECHING)

23
00:01:03,405 --> 00:01:05,244
(DEEP GROWLING)

24
00:01:05,285 --> 00:01:06,765
..and escape.

25
00:01:06,805 --> 00:01:08,805
(PADDING AND RUSTLING)

26
00:01:08,845 --> 00:01:10,605
(SOFT THUDDING)

27
00:01:13,965 --> 00:01:17,765
Sound can make the difference
between life and death.

28
00:01:19,005 --> 00:01:20,365
(SCUFFING)

29
00:01:20,405 --> 00:01:21,925
(SCUFFING AND PATTERING)

30
00:01:21,965 --> 00:01:23,405
(HISSES)

31
00:01:23,445 --> 00:01:25,965
It's time to open your ears

32
00:01:26,005 --> 00:01:29,285
to life
as you've never heard it before.

33
00:01:29,325 --> 00:01:32,525
(GRUMBLING AND TRUMPETING)

34
00:01:36,925 --> 00:01:38,925
(CHIRRUPING AND TWITTERING)

35
00:01:39,965 --> 00:01:42,405
(SQUAWKING AND SCREECHING)

36
00:01:42,445 --> 00:01:44,445
(DEEP RUMBLING GROWL)

37
00:01:48,805 --> 00:01:49,805
(CHIRRUPING)

38
00:01:52,125 --> 00:01:54,125
(SQUAWKING AND SCREECHING)

39
00:01:55,085 --> 00:01:57,445
(GRUNTING)

40
00:01:57,484 --> 00:01:59,484
(CHITTERING AND CROAKING)

41
00:02:01,485 --> 00:02:03,485
(CACOPHONY OF ANIMAL CALLS)

42
00:02:06,125 --> 00:02:08,125
(SOFT MOANING)

43
00:02:10,965 --> 00:02:12,965
(CHIRPS)

44
00:02:14,125 --> 00:02:17,805
Dawn on the African savanna.

45
00:02:17,845 --> 00:02:19,885
(GRUNTING)

46
00:02:19,925 --> 00:02:21,445
(BELLOWING)

47
00:02:22,565 --> 00:02:24,565
(GRUNTING AND BELLOWING)

48
00:02:28,925 --> 00:02:31,645
It's the best time of the day

49
00:02:31,685 --> 00:02:35,245
for lions to broadcast their message.

50
00:02:36,045 --> 00:02:37,045
(GRUNTS)

51
00:02:38,245 --> 00:02:39,365
(BELLOWS HOARSELY)

52
00:02:41,845 --> 00:02:43,965
(BELLOWS HOARSELY)

53
00:02:44,005 --> 00:02:46,245
(BELLOWING CONTINUES)

54
00:02:46,285 --> 00:02:51,405
As the sun rises,
cold air is trapped near the ground.

55
00:02:52,645 --> 00:02:54,565
Because it's denser than warm air,

56
00:02:54,605 --> 00:02:58,005
it allows sound to travel further
before dissipating.

57
00:02:58,045 --> 00:02:59,645
(GRUNTING ECHOES)

58
00:02:59,685 --> 00:03:00,685
(GRUNTS)

59
00:03:03,725 --> 00:03:06,445
It's a declaration to other prides

60
00:03:06,485 --> 00:03:09,005
of his ownership
of these hunting grounds...

61
00:03:11,245 --> 00:03:14,845
..and the key to his
and his pride's survival.

62
00:03:14,885 --> 00:03:16,525
(RUMBLING GROWL)

63
00:03:16,565 --> 00:03:18,405
(BELLOWS)

64
00:03:18,445 --> 00:03:22,525
It's one of the greatest
acoustic displays of power in nature.

65
00:03:22,565 --> 00:03:24,365
(HIGH-PITCHED BELLOW)

66
00:03:26,045 --> 00:03:27,245
(DEEP RUMBLING ROAR)

67
00:03:30,685 --> 00:03:31,725
(GRUNTS AND ROARS)

68
00:03:34,565 --> 00:03:35,605
(GRUNTS AND ROARS)

69
00:03:37,405 --> 00:03:39,325
(GRUNTS)

70
00:03:39,365 --> 00:03:42,605
He can be heard
up to five miles away.

71
00:03:42,645 --> 00:03:44,525
(RUMBLING ROAR)

72
00:03:44,565 --> 00:03:46,005
(DEEP GRUNTING)

73
00:03:46,045 --> 00:03:47,925
But even this isn't far enough

74
00:03:47,965 --> 00:03:50,285
to reach the boundaries
of their territory.

75
00:03:53,165 --> 00:03:57,005
It spans over 150 square miles.

76
00:03:58,325 --> 00:04:00,805
To defend an area
as immense as this,

77
00:04:00,845 --> 00:04:03,725
the pride must roam and roar.

78
00:04:03,765 --> 00:04:05,765
(SONOROUS RUMBLING ROAR)

79
00:04:09,925 --> 00:04:13,485
But some members are too small
to get very far.

80
00:04:13,525 --> 00:04:15,805
(YOWLS)

81
00:04:19,485 --> 00:04:23,045
This pride is protected
by three brothers.

82
00:04:25,685 --> 00:04:28,565
Together, they head off on patrol.

83
00:04:33,485 --> 00:04:38,405
A lion's roar sends a clear message
to other prides.

84
00:04:42,685 --> 00:04:46,325
But sound can also be used
in more subtle ways.

85
00:04:46,365 --> 00:04:48,365
(CHIRRUPING)

86
00:04:49,045 --> 00:04:51,005
(TWITTERING AND CHIRPING)

87
00:04:51,045 --> 00:04:53,045
(LOW BUZZING)

88
00:04:53,925 --> 00:04:55,925
(BUZZING CONTINUES)

89
00:04:57,605 --> 00:04:59,605
(BUZZING AND HUMMING)

90
00:05:05,805 --> 00:05:07,485
(INTENSE BUZZING)

91
00:05:08,485 --> 00:05:13,205
This garden is filled with the sound
of the buzzing of bees.

92
00:05:13,245 --> 00:05:18,205
It's a sign that the plants have been
successful in attracting pollinators

93
00:05:18,245 --> 00:05:20,365
with their brightly-coloured flowers

94
00:05:20,405 --> 00:05:22,405
and seductive smells.

95
00:05:24,325 --> 00:05:26,325
(INTENSE BUZZING)

96
00:05:27,205 --> 00:05:30,405
The buzzing sound
we associate with bees

97
00:05:30,445 --> 00:05:35,245
is a by-product created by
the beating wings as they fly.

98
00:05:35,285 --> 00:05:37,285
(BUZZING)

99
00:05:38,365 --> 00:05:40,365
(BUZZING)

100
00:05:40,405 --> 00:05:43,965
But some bees
take advantage of their buzz,

101
00:05:44,005 --> 00:05:47,445
and use it,
in a surprisingly sophisticated way,

102
00:05:47,485 --> 00:05:50,965
to get to a supply of food
that others can't reach.

103
00:05:51,845 --> 00:05:53,845
(BUZZING)

104
00:06:00,085 --> 00:06:03,245
One such bee lives underground.

105
00:06:06,485 --> 00:06:08,485
(BUZZING THRUM)

106
00:06:09,965 --> 00:06:14,005
These are buff-tailed bumblebees.

107
00:06:15,605 --> 00:06:17,445
For the colony to survive,

108
00:06:17,485 --> 00:06:20,525
each worker must collect
as much pollen as she can

109
00:06:20,565 --> 00:06:22,565
with which to feed their young.

110
00:06:22,605 --> 00:06:24,685
(CONTINUOUS BUZZING THRUM)

111
00:06:25,565 --> 00:06:28,525
Searching for it
is a constant preoccupation.

112
00:06:33,365 --> 00:06:35,325
(SOFT RUSTLING)

113
00:06:35,365 --> 00:06:37,164
(INTREPID MUSIC)

114
00:06:42,805 --> 00:06:44,805
(BUZZING)

115
00:06:50,485 --> 00:06:52,685
It's spring in England...

116
00:06:55,725 --> 00:06:57,645
(BUZZING)

117
00:06:57,685 --> 00:06:59,125
(SOFT FLUTTERING)

118
00:07:00,725 --> 00:07:02,205
(FLUTTERING AND CLICKING)

119
00:07:02,245 --> 00:07:03,725
(GENTLE BUZZING)

120
00:07:03,765 --> 00:07:07,085
..and she is not the only one
in search of food.

121
00:07:09,085 --> 00:07:12,565
Competition for pollen and nectar
is high.

122
00:07:14,325 --> 00:07:17,485
And poppies are putting on a show.

123
00:07:19,805 --> 00:07:21,645
Packed full of pollen,

124
00:07:21,685 --> 00:07:25,365
they flaunt it at the top
of long filaments called anthers.

125
00:07:26,725 --> 00:07:28,725
(BUZZING)

126
00:07:29,445 --> 00:07:31,805
These flowers are a free-for-all...

127
00:07:33,285 --> 00:07:35,965
..and everyone
is seeking a share of the bounty.

128
00:07:36,005 --> 00:07:38,005
(BUZZING)

129
00:07:40,445 --> 00:07:43,085
(HARMONIOUS BUZZING)

130
00:07:53,885 --> 00:07:57,245
But she doesn't need to compete
with other species

131
00:07:57,285 --> 00:08:00,685
if she can find
a particular kind of flower.

132
00:08:02,245 --> 00:08:04,245
(SOFT FLUTTERING)

133
00:08:11,445 --> 00:08:14,005
She's found
what she's been looking for...

134
00:08:14,045 --> 00:08:16,245
(SOFT BUZZING AND FLUTTERING)

135
00:08:16,285 --> 00:08:18,085
..a type of nightshade.

136
00:08:18,885 --> 00:08:20,885
(BUZZING)

137
00:08:25,005 --> 00:08:27,605
Its flowers are less striking

138
00:08:27,645 --> 00:08:29,285
and, unlike poppies,

139
00:08:29,325 --> 00:08:33,005
its pollen is locked up
inside long yellow anthers.

140
00:08:35,684 --> 00:08:39,564
The only way for it to escape
is through tiny holes.

141
00:08:43,804 --> 00:08:45,805
The bumblebee holds the key

142
00:08:45,845 --> 00:08:48,365
that unlocks this treasury of pollen.

143
00:08:50,125 --> 00:08:51,845
Sound.

144
00:08:52,965 --> 00:08:54,885
Locking in her wings,

145
00:08:54,925 --> 00:08:58,285
she uses her flight muscles
to vibrate her whole body,

146
00:08:58,325 --> 00:09:02,005
buzzing up to 370 times a second.

147
00:09:02,045 --> 00:09:05,245
(INTENSE BUZZING)

148
00:09:09,565 --> 00:09:13,565
This sonic assault
blasts the pollen loose.

149
00:09:13,605 --> 00:09:15,605
(BUZZING CONTINUES)

150
00:09:25,005 --> 00:09:29,605
She then grooms the pollen
down into sticky sacs on her legs

151
00:09:29,645 --> 00:09:31,645
and flies off to the next flower.

152
00:09:31,685 --> 00:09:33,685
(INTENSE BUZZING)

153
00:09:38,605 --> 00:09:42,565
Very few species
can buzz-pollinate in this way,

154
00:09:42,605 --> 00:09:48,085
so bumblebees have nearly exclusive
access to the nightshades' pollen.

155
00:09:48,125 --> 00:09:50,125
(INTENSE BUZZING)

156
00:09:55,645 --> 00:09:58,445
The bee's pollination buzz
is higher pitched

157
00:09:58,485 --> 00:10:00,485
than that made during flight.

158
00:10:03,325 --> 00:10:06,605
It's the same frequency
as the musical note D.

159
00:10:06,645 --> 00:10:08,645
(HIGH-PITCHED BUZZING)

160
00:10:13,965 --> 00:10:16,445
She's like a living tuning fork.

161
00:10:18,245 --> 00:10:21,725
Some buzz pollinators
can vary their pitch,

162
00:10:21,765 --> 00:10:24,685
fine-tuning it
to suit different flowers.

163
00:10:24,725 --> 00:10:28,485
So pollen is released
in the most efficient way.

164
00:10:33,565 --> 00:10:36,685
Fully loaded,
she returns to the hive.

165
00:10:44,205 --> 00:10:46,565
She has successfully used sound

166
00:10:46,605 --> 00:10:49,605
to help secure the pollen
her colony needs.

167
00:10:49,645 --> 00:10:52,005
(CONTINUOUS HUMMING)

168
00:10:56,645 --> 00:10:58,885
We tend to take bees for granted...

169
00:10:59,685 --> 00:11:04,045
but it's not just plants
that depend on them, we do too.

170
00:11:05,205 --> 00:11:08,245
Many of our crops rely on pollinators

171
00:11:08,285 --> 00:11:10,725
like bees and other insects.

172
00:11:12,125 --> 00:11:15,365
Worryingly, bee populations,

173
00:11:15,405 --> 00:11:18,725
together with those
of many other insect pollinators,

174
00:11:18,765 --> 00:11:22,565
are in serious decline
around the world.

175
00:11:23,525 --> 00:11:25,365
And with their numbers plummeting,

176
00:11:25,405 --> 00:11:29,925
both the natural world and our own
food supplies are in danger.

177
00:11:29,965 --> 00:11:31,645
(CONTINUOUS BUZZING)

178
00:11:31,685 --> 00:11:34,245
Bees need our help

179
00:11:34,285 --> 00:11:37,325
and without them
and the sound of their buzz,

180
00:11:37,365 --> 00:11:40,405
the future for us all
would look bleak.

181
00:11:42,165 --> 00:11:44,165
(INTENSE BUZZING)

182
00:11:48,245 --> 00:11:51,125
Sound provides the key
to this partnership

183
00:11:51,165 --> 00:11:53,325
between bumble bees and plants.

184
00:11:55,845 --> 00:11:59,245
But not all relationships in nature
are as harmonious.

185
00:11:59,285 --> 00:12:01,365
(BIRDSONG)

186
00:12:01,405 --> 00:12:03,405
(DISTANT BIRD CALLS)

187
00:12:04,485 --> 00:12:07,165
The Bahama Islands in the Caribbean.

188
00:12:14,725 --> 00:12:17,005
The sand flats here are the home

189
00:12:17,045 --> 00:12:19,605
of garden eels and razorfish.

190
00:12:19,645 --> 00:12:21,645
(WATER BURBLES GENTLY)

191
00:12:26,765 --> 00:12:29,245
(FAINT SQUEAKING)

192
00:12:29,285 --> 00:12:32,125
But there is trouble in paradise.

193
00:12:32,165 --> 00:12:34,165
(ECHOEY CLICKING AND SQUEAKING)

194
00:12:36,285 --> 00:12:38,605
The sound of approaching danger.

195
00:12:38,645 --> 00:12:42,565
(ECHOEY RHYTHMIC SQUEAKING)

196
00:12:42,605 --> 00:12:44,605
It's a cue to hide.

197
00:12:44,645 --> 00:12:47,165
(ECHOEY WHISTLING AND SQUEAKING)

198
00:12:52,285 --> 00:12:54,445
(SQUEAKING AND CLICKING)

199
00:12:54,485 --> 00:12:58,645
A mixed groups
of spotted and bottlenose dolphins.

200
00:12:58,685 --> 00:13:00,885
(SQUEAKING AND WHISTLING)

201
00:13:03,525 --> 00:13:07,805
Their whistles and squeaks are part
of their continuous conversations...

202
00:13:07,845 --> 00:13:09,485
(CLICKING)

203
00:13:09,525 --> 00:13:13,525
..with a range of frequencies
seven times greater than ours.

204
00:13:13,565 --> 00:13:15,565
(HIGH-PITCHED SQUEAKING)

205
00:13:16,725 --> 00:13:18,725
(CLICKING AND SQUEAKING)

206
00:13:25,765 --> 00:13:28,405
To hunt for food, they must split up.

207
00:13:28,445 --> 00:13:30,965
(CLICKING AND WHISTLING)

208
00:13:31,005 --> 00:13:35,445
Each dolphin
needs 15 kilograms of fish a day.

209
00:13:36,605 --> 00:13:39,085
(CHIRRUPING)

210
00:13:39,125 --> 00:13:41,405
But, thanks to their rowdy arrival,

211
00:13:42,365 --> 00:13:44,365
there isn't a morsel in sight.

212
00:13:47,085 --> 00:13:49,085
The hunt is on.

213
00:13:51,245 --> 00:13:54,205
(LOW GRUMBLING)

214
00:13:56,250 --> 00:13:58,245
(LOW GRUMBLING)

215
00:13:59,245 --> 00:14:01,645
(CLICKING AND CHIRRUPING)

216
00:14:01,685 --> 00:14:04,885
The bottlenose dolphins
now switch from whistles

217
00:14:04,925 --> 00:14:07,245
to bursts of fast clicks,

218
00:14:07,285 --> 00:14:09,445
up to 200 per second.

219
00:14:09,485 --> 00:14:11,485
(RAPID CLICKING)

220
00:14:14,245 --> 00:14:16,285
(INTENSE HIGH-FREQUENCY CLICKING)

221
00:14:18,605 --> 00:14:22,885
These high-frequency clicks
are sent out like a sonar beam

222
00:14:22,925 --> 00:14:25,885
through an organ in the forehead
called a melon,

223
00:14:25,925 --> 00:14:28,725
with which
they can scan the ocean floor.

224
00:14:28,765 --> 00:14:30,765
(RAPID CLICKING)

225
00:14:38,525 --> 00:14:42,405
When the beam of sound
hits a fish hiding beneath the sand,

226
00:14:42,445 --> 00:14:46,405
it's reflected back,
revealing its location.

227
00:14:46,445 --> 00:14:47,925
(CLICKING)

228
00:14:47,965 --> 00:14:49,565
Using echolocation,

229
00:14:49,605 --> 00:14:52,645
the dolphins are able
to create a visual map

230
00:14:52,685 --> 00:14:54,885
of what is hidden
under the sea floor.

231
00:14:54,925 --> 00:14:57,565
(RAPID CLICKING)

232
00:15:06,365 --> 00:15:09,285
Some of these clicks
are ten times higher

233
00:15:09,325 --> 00:15:12,165
than the sounds our ears can detect.

234
00:15:12,205 --> 00:15:14,405
(HIGH-PITCHED CLICKING)

235
00:15:14,445 --> 00:15:15,765
(SILENCE)

236
00:15:15,805 --> 00:15:19,845
High-frequency sounds
are most effective at close range,

237
00:15:19,885 --> 00:15:24,245
enabling the dolphins to pinpoint
their prey with great precision.

238
00:15:31,925 --> 00:15:36,725
But there is more to these
pirouettes than meets the eye.

239
00:15:36,765 --> 00:15:38,845
(CLICKING)

240
00:15:38,885 --> 00:15:43,565
Scientists have recently discovered
that bottlenose dolphins

241
00:15:43,605 --> 00:15:46,885
favour their
right side when scanning the seabed.

242
00:15:49,365 --> 00:15:54,045
The right side of the head
usually produces the sonar clicks.

243
00:15:54,085 --> 00:15:58,365
And the right side is also better
at detecting the returning echo.

244
00:15:58,405 --> 00:16:00,405
(CLICKING)

245
00:16:01,485 --> 00:16:03,485
(MELLIFLUOUS MUSIC)

246
00:16:11,925 --> 00:16:15,845
The only evidence that there has been
a sonar search here

247
00:16:15,885 --> 00:16:18,725
are small craters in the sand.

248
00:16:33,085 --> 00:16:36,005
Dolphins use sound with great effect

249
00:16:36,045 --> 00:16:38,045
to find their food.

250
00:16:38,885 --> 00:16:41,965
But in other places,
a quieter approach

251
00:16:42,005 --> 00:16:44,245
is the key to a successful hunt.

252
00:16:45,805 --> 00:16:47,805
(DISTANT SQUAWKING)

253
00:16:48,805 --> 00:16:50,845
(DISTANT CHIRRUPING)

254
00:16:50,885 --> 00:16:52,645
(SQUAWKING)

255
00:16:52,685 --> 00:16:54,685
(SOFT RUSTLING)

256
00:16:55,325 --> 00:16:58,165
In the forests of Manitoba
in Canada,

257
00:16:58,205 --> 00:17:02,565
the great grey owl
is a master of silence.

258
00:17:11,485 --> 00:17:13,844
Specially-adapted flight feathers

259
00:17:13,885 --> 00:17:16,285
allow him to approach silently.

260
00:17:17,005 --> 00:17:19,005
(WIND GUSTS GENTLY)

261
00:17:28,324 --> 00:17:31,925
His prey is hidden
under a blanket of snow.

262
00:17:38,645 --> 00:17:40,645
(SOFT SNUFFLING)

263
00:17:43,005 --> 00:17:44,925
Voles.

264
00:17:47,485 --> 00:17:51,085
Finding them in this vast,
snow-covered landscape

265
00:17:51,125 --> 00:17:53,485
seems an impossible task.

266
00:17:57,045 --> 00:17:59,965
To combat the extreme cold,

267
00:18:00,005 --> 00:18:02,685
he must catch seven voles a day.

268
00:18:04,445 --> 00:18:07,325
His ears will be
his most effective weapon.

269
00:18:09,925 --> 00:18:11,685
(SNUFFLES AND SQUEAKS)

270
00:18:13,245 --> 00:18:16,085
Voles need to feed continuously

271
00:18:16,125 --> 00:18:18,045
or they will freeze to death.

272
00:18:18,845 --> 00:18:20,845
(HIGH-PITCHED SQUEAKING)

273
00:18:21,645 --> 00:18:23,845
(PATTERING FOOTSTEPS)

274
00:18:23,885 --> 00:18:28,045
They constantly dig tunnels
to find new food supplies...

275
00:18:29,805 --> 00:18:32,125
..unaware of the danger above.

276
00:18:32,165 --> 00:18:34,165
(SNUFFLING AND SCUFFLING)

277
00:18:37,205 --> 00:18:40,405
Hidden under a face
covered by feathers,

278
00:18:40,445 --> 00:18:42,885
the owl's ears are positioned

279
00:18:42,925 --> 00:18:46,725
at slightly different levels
on either side of his head.

280
00:18:49,045 --> 00:18:51,645
Sound will hit one ear
before the other,

281
00:18:51,685 --> 00:18:55,605
allowing him to pinpoint his prey
with great accuracy.

282
00:19:01,645 --> 00:19:04,365
His acoustic arsenal
doesn't stop there.

283
00:19:07,685 --> 00:19:10,045
The large facial ruff,

284
00:19:10,085 --> 00:19:13,445
formed from feathers that are
particularly stiff and dense,

285
00:19:13,485 --> 00:19:17,485
help to amplify sound
and funnel it towards the ears.

286
00:19:26,445 --> 00:19:28,445
(RUSTLING AND SQUEAKING)

287
00:19:30,805 --> 00:19:33,285
Through half a metre of snow,

288
00:19:33,325 --> 00:19:37,005
the sound of scampering feet
is inaudible to us.

289
00:19:40,405 --> 00:19:42,685
But it's loud enough for him.

290
00:19:48,445 --> 00:19:50,445
With the help of a specialist camera

291
00:19:50,485 --> 00:19:54,725
equipped
with 60 highly-sensitive microphones,

292
00:19:54,765 --> 00:19:57,485
we can reveal
what the owl is hearing.

293
00:19:58,485 --> 00:19:59,885
(FAINT SCUFFLING)

294
00:19:59,925 --> 00:20:03,925
The camera visualises
where the vole is beneath the snow.

295
00:20:06,685 --> 00:20:07,685
(SNUFFLES)

296
00:20:18,725 --> 00:20:20,725
And he's off.

297
00:20:24,885 --> 00:20:26,725
(SCUFFLES AND SNIFFS)

298
00:20:31,805 --> 00:20:33,805
(CRUNCHING)

299
00:20:38,205 --> 00:20:40,285
This time he's missed.

300
00:20:46,565 --> 00:20:48,565
(RUSTLING)

301
00:20:49,845 --> 00:20:54,925
Despite his acute hearing,
hunting in snow is a challenge.

302
00:20:57,925 --> 00:21:00,445
The snow not only muffles sound,

303
00:21:00,485 --> 00:21:02,485
it bends it too.

304
00:21:05,405 --> 00:21:08,285
While it appears
as if the vole is here,

305
00:21:08,325 --> 00:21:10,325
it's actually over there.

306
00:21:15,165 --> 00:21:18,805
The only way to defeat
this acoustic illusion,

307
00:21:18,845 --> 00:21:22,245
is for the owl
to get directly above the vole,

308
00:21:22,285 --> 00:21:25,285
where sound is no longer distorted
by the snow.

309
00:21:25,325 --> 00:21:27,325
(WIND GUSTS SOFTLY)

310
00:21:37,725 --> 00:21:41,885
As he flies,
he tracks the sound as it changes.

311
00:21:43,885 --> 00:21:45,965
(SUSPENSEFUL MUSIC)

312
00:21:49,285 --> 00:21:53,165
The closer he gets,
the less the sound is bent.

313
00:21:55,725 --> 00:21:59,765
Directly above the vole,
he can pinpoint his target.

314
00:22:06,085 --> 00:22:07,445
(VOLE SQUEAKS)

315
00:22:18,525 --> 00:22:20,525
The great grey owl's hearing

316
00:22:20,565 --> 00:22:23,005
is its key to securing a meal.

317
00:22:25,165 --> 00:22:28,885
For others,
it's crucial to avoid being eaten.

318
00:22:29,925 --> 00:22:32,325
(CHIRRUPING)

319
00:22:32,365 --> 00:22:35,685
In the Arizona desert,
it's the height of summer.

320
00:22:38,565 --> 00:22:42,525
Daytime temperatures
are over 40 degrees Celsius.

321
00:22:43,845 --> 00:22:46,525
So it's best to be active at night.

322
00:22:48,645 --> 00:22:51,965
Filming under infra-red lights
with a specialist camera...

323
00:22:53,245 --> 00:22:55,245
..we can see everything.

324
00:22:55,285 --> 00:22:57,045
(WIND GUSTS SOFTLY)

325
00:22:59,165 --> 00:23:01,525
But to a kangaroo rat,

326
00:23:01,565 --> 00:23:03,565
it's nearly pitch black.

327
00:23:06,965 --> 00:23:10,725
In the dark,
her most valuable ally is sound.

328
00:23:10,765 --> 00:23:12,765
(WIND GUSTS AND PLANTS RUSTLE)

329
00:23:13,725 --> 00:23:15,285
(SNIFFS)

330
00:23:19,565 --> 00:23:23,565
Her mission tonight is to collect
as many seeds as she can.

331
00:23:26,685 --> 00:23:28,685
But food is scarce...

332
00:23:30,725 --> 00:23:32,725
..and competition fierce.

333
00:23:33,725 --> 00:23:35,085
(SNIFFS)

334
00:23:36,765 --> 00:23:39,805
And, in the dark,
it's hard to spot danger.

335
00:23:40,565 --> 00:23:42,205
(SCUFFLING)

336
00:23:42,245 --> 00:23:44,245
(FOREBODING MUSIC)

337
00:23:45,445 --> 00:23:47,525
(SOFT RUSTLING)

338
00:23:48,605 --> 00:23:52,045
Her ears are 90 times
more sensitive than ours...

339
00:23:52,805 --> 00:23:54,805
and hollow spaces in her skull

340
00:23:54,845 --> 00:23:56,845
act like an echo chamber,

341
00:23:56,885 --> 00:23:59,405
amplifying the faintest of sounds.

342
00:23:59,445 --> 00:24:01,245
(RUSTLING)

343
00:24:02,765 --> 00:24:04,445
(RUSTLING)

344
00:24:05,645 --> 00:24:07,845
But she has
another problem tonight.

345
00:24:08,525 --> 00:24:10,525
(WIND HOWLS)

346
00:24:11,885 --> 00:24:13,885
(WIND GUSTS AND SAND RUSTLES)

347
00:24:13,925 --> 00:24:15,205
Wind.

348
00:24:15,245 --> 00:24:17,205
(WIND HOWLS)

349
00:24:17,965 --> 00:24:20,165
(SAND RUSTLES)

350
00:24:23,205 --> 00:24:26,925
She might not hear a predator
until it's too late.

351
00:24:32,085 --> 00:24:34,485
This time, it's just a stick.

352
00:24:36,085 --> 00:24:39,205
But, in the darkness,
she's right to be cautious.

353
00:24:43,525 --> 00:24:46,765
Snakes can pick up
the sounds of scampering feet

354
00:24:46,805 --> 00:24:48,765
through their lower jaw.

355
00:24:49,525 --> 00:24:51,085
(SOFT RUSTLING)

356
00:24:55,205 --> 00:24:56,205
(SNIFFS)

357
00:24:57,325 --> 00:25:00,325
She's made it
to her favourite feeding spot.

358
00:25:01,805 --> 00:25:04,285
But she's not alone for long.

359
00:25:13,645 --> 00:25:19,605
She warns him to stay away
by drumming her foot on the ground.

360
00:25:19,645 --> 00:25:21,645
(TAPPING)

361
00:25:24,885 --> 00:25:27,925
(TAPPING ECHOES)
He can decipher her size and strength

362
00:25:27,965 --> 00:25:29,965
from her signal.

363
00:25:30,005 --> 00:25:32,005
(TAPPING)

364
00:25:35,325 --> 00:25:37,045
He drums back.

365
00:25:37,085 --> 00:25:39,285
(TAPPING)

366
00:25:39,325 --> 00:25:41,885
It's a battle of beats.

367
00:25:41,925 --> 00:25:43,925
(TAPPING ECHOES)

368
00:25:45,205 --> 00:25:47,525
(TAPPING CONTINUES)

369
00:25:50,565 --> 00:25:51,845
Stalemate.

370
00:25:52,845 --> 00:25:54,885
There's only one
way to resolve this.

371
00:25:55,645 --> 00:25:57,645
(DRAMATIC ORCHESTRAL MUSIC)

372
00:26:17,045 --> 00:26:18,845
(MUSIC FADES)

373
00:26:21,805 --> 00:26:23,805
Dinner time at last.

374
00:26:36,085 --> 00:26:37,845
She hears something.

375
00:26:39,565 --> 00:26:41,565
(OMINOUS MUSIC)

376
00:26:45,205 --> 00:26:48,765
Just out of striking range,
she drums again...

377
00:26:49,565 --> 00:26:51,565
(TAPPING)

378
00:26:52,805 --> 00:26:56,925
..this time to alert the snake
it's been spotted.

379
00:26:58,845 --> 00:27:00,845
But just to be sure...

380
00:27:00,885 --> 00:27:02,285
(SCUFFING AND RUSTLING)

381
00:27:04,125 --> 00:27:06,685
(RUSTLING)

382
00:27:06,725 --> 00:27:08,245
(HISSES)

383
00:27:11,645 --> 00:27:13,645
Message received.

384
00:27:20,765 --> 00:27:23,485
While kangaroo rats
use the ground as a drum

385
00:27:23,525 --> 00:27:25,845
to drive their enemies away...

386
00:27:26,565 --> 00:27:29,845
others are summoned
by seismic sounds.

387
00:27:33,885 --> 00:27:35,885
(LOW GRUMBLING)

388
00:27:38,886 --> 00:27:40,885
(LOW GRUMBLING)

389
00:27:41,885 --> 00:27:43,885
(WIND WHISTLES)

390
00:27:46,205 --> 00:27:48,205
(WHOOSHING)

391
00:27:50,725 --> 00:27:53,325
Amboseli National Park in Kenya.

392
00:27:54,925 --> 00:27:57,845
It hasn't rained here
in nearly a year...

393
00:27:57,885 --> 00:27:59,885
(DEEP GRUMBLING)

394
00:28:01,165 --> 00:28:04,725
..and the dry season
has turned into a severe drought.

395
00:28:06,485 --> 00:28:08,805
(CACOPHONY OF SCREECHING
AND SQUAWKING)

396
00:28:12,325 --> 00:28:15,525
For elephants,
the situation is desperate.

397
00:28:15,565 --> 00:28:18,045
(LOW GRUMBLING)

398
00:28:19,045 --> 00:28:21,765
With no food or water
for miles around,

399
00:28:21,805 --> 00:28:24,645
the matriarch
must wait for a message...

400
00:28:25,685 --> 00:28:28,765
..a sound that will travel
through the ground.

401
00:28:29,525 --> 00:28:31,245
(LOW GRUMBLING)

402
00:28:31,285 --> 00:28:33,285
(HUFFING)

403
00:28:37,525 --> 00:28:40,805
If it arrives,
it will guide them from disaster.

404
00:28:44,685 --> 00:28:47,525
The young calves
are especially vulnerable.

405
00:28:49,485 --> 00:28:50,885
(GRUNTING)

406
00:28:51,685 --> 00:28:56,245
Their mother's milk will dry up
if rain doesn't arrive soon.

407
00:28:58,685 --> 00:29:00,685
(WIND WHISTLES)

408
00:29:03,085 --> 00:29:05,085
(LOW GRUMBLING)

409
00:29:09,765 --> 00:29:11,565
(RUMBLING AND GUSTING)

410
00:29:11,605 --> 00:29:15,805
A hundred miles away,
a storm has broken...

411
00:29:15,845 --> 00:29:17,845
(THUNDERCLAP)

412
00:29:21,445 --> 00:29:23,525
..and the elephants have heard.

413
00:29:24,845 --> 00:29:26,045
(THUNDER RUMBLES)

414
00:29:26,085 --> 00:29:28,005
(LIGHTNING CRACKLES)

415
00:29:29,285 --> 00:29:31,285
Not with their ears...

416
00:29:32,965 --> 00:29:34,885
..but with their feet.

417
00:29:35,605 --> 00:29:37,805
(RAIN SPLATTERS)

418
00:29:38,765 --> 00:29:42,045
The sound of the storm
sends low-frequency vibrations

419
00:29:42,085 --> 00:29:44,485
through the ground.

420
00:29:44,525 --> 00:29:46,965
(AMPLIFIED RUMBLING)

421
00:29:48,805 --> 00:29:50,965
The herd picks up the vibrations

422
00:29:51,005 --> 00:29:54,565
through a network of nerves
in the fatty pads of their feet.

423
00:29:54,605 --> 00:29:56,605
(AMPLIFIED RUMBLING)

424
00:29:57,605 --> 00:29:59,645
(HEAVY SPLASHING)

425
00:30:02,605 --> 00:30:04,165
By lifting one foot,

426
00:30:04,205 --> 00:30:07,405
they can make better contact
on the ground with the other.

427
00:30:09,645 --> 00:30:12,045
(STEADY PATTERING)

428
00:30:12,085 --> 00:30:15,565
It's the message the matriarch
has been waiting for.

429
00:30:15,605 --> 00:30:17,605
(LOW GRUMBLING)

430
00:30:18,645 --> 00:30:21,485
She gives a low "let's go" rumble.

431
00:30:22,965 --> 00:30:24,965
(LOW GRUMBLING)

432
00:30:25,645 --> 00:30:28,005
It's echoed by her sisters.

433
00:30:28,045 --> 00:30:30,045
(GRUNTING AND GRUMBLING)

434
00:30:34,085 --> 00:30:36,645
The journey ahead is treacherous...

435
00:30:38,085 --> 00:30:41,045
..but the sound of the storm
will be their guide.

436
00:30:41,085 --> 00:30:42,485
(TRUMPETING)

437
00:30:44,165 --> 00:30:45,485
(GRUNTS AND SCREECHES)

438
00:30:47,925 --> 00:30:49,925
(LOW GRUMBLING)

439
00:30:53,805 --> 00:30:55,805
(WIND WHOOSHES)

440
00:30:56,525 --> 00:30:59,085
Finally,
after two days on the move...

441
00:31:00,085 --> 00:31:02,085
..they've made it.

442
00:31:04,885 --> 00:31:08,845
Their ability to detect sound
a hundred miles away

443
00:31:08,885 --> 00:31:10,885
has saved the herd.

444
00:31:12,805 --> 00:31:14,805
(THUNDER RUMBLES)

445
00:31:16,765 --> 00:31:20,965
Elephants aren't the only ones
who respond to the sound of rain.

446
00:31:23,925 --> 00:31:26,685
But sometimes
sounds can be deceptive.

447
00:31:30,725 --> 00:31:34,605
In Vancouver, in Canada,
it's also raining.

448
00:31:36,485 --> 00:31:39,085
(HISSING AND PATTERING)

449
00:31:46,165 --> 00:31:48,165
(STEADY PATTERING)

450
00:32:07,405 --> 00:32:11,805
Underground the soil
is teeming with earthworms.

451
00:32:13,605 --> 00:32:18,165
Some rise to the surface
in search of food or mates.

452
00:32:20,925 --> 00:32:24,765
But if the ground isn't wet enough,
they risk drying out.

453
00:32:26,965 --> 00:32:30,085
Sound helps them
pick the opportune moment.

454
00:32:31,685 --> 00:32:33,445
(SPLASHING)

455
00:32:33,485 --> 00:32:35,245
As the rain hits the ground,

456
00:32:35,285 --> 00:32:39,525
it creates vibrations
that travel down into the soil.

457
00:32:44,725 --> 00:32:48,725
They are picked up by sensitive
nerve cells in the worm's skin.

458
00:32:50,805 --> 00:32:54,125
As they rise,
the tumultuous pitter-patter

459
00:32:54,165 --> 00:32:56,165
is music to their senses.

460
00:32:57,365 --> 00:32:59,365
(STEADY PATTERING)

461
00:33:01,245 --> 00:33:04,765
But it is also a sound
that can seal their fate.

462
00:33:06,325 --> 00:33:09,765
Worms aren't the only ones
on the move.

463
00:33:11,645 --> 00:33:13,445
(GULLS SQUAWKING)

464
00:33:13,485 --> 00:33:15,965
Outside the city, a flock of gulls

465
00:33:16,005 --> 00:33:19,205
are co-ordinating their
morning departure from the roost.

466
00:33:19,245 --> 00:33:22,245
(CACOPHONY OF SQUAWKING
AND SCREECHING)

467
00:33:32,045 --> 00:33:36,165
Thanks to the rain, they've got
a special meal on the menu today.

468
00:33:37,605 --> 00:33:38,925
Worms!

469
00:33:40,765 --> 00:33:43,165
But by the time they arrive,

470
00:33:43,205 --> 00:33:45,485
the downpour is over...

471
00:33:48,645 --> 00:33:51,525
..and the worms
are already retreating.

472
00:33:56,005 --> 00:33:58,165
Dining options look scarce...

473
00:33:59,325 --> 00:34:02,085
..but the gulls have a crafty trick.

474
00:34:04,285 --> 00:34:07,165
For it to work,
they must find their rhythm.

475
00:34:07,845 --> 00:34:09,845
(SOFT RHYTHMIC TAPPING)

476
00:34:15,525 --> 00:34:20,525
Paddling creates vibrations that
likely mimics the sound of rain.

477
00:34:24,525 --> 00:34:27,244
It's a dance of deception.

478
00:34:29,125 --> 00:34:32,365
(MUFFLED TAPPING)
The worms rise once again.

479
00:34:32,405 --> 00:34:34,405
(MUFFLED TAPPING)

480
00:34:39,325 --> 00:34:42,445
They can't resist
the rhythmic rain dance.

481
00:34:48,525 --> 00:34:50,005
(RHYTHMIC TAPPING)

482
00:35:00,885 --> 00:35:02,445
(STEADY PATTERING)

483
00:35:02,485 --> 00:35:06,285
Another shower
brings an acoustic climax.

484
00:35:07,125 --> 00:35:08,765
(RHYTHMIC TAPPING)

485
00:35:14,565 --> 00:35:17,165
The rainy season
will last all winter,

486
00:35:17,205 --> 00:35:20,325
so worms are on the menu
until spring.

487
00:35:23,845 --> 00:35:27,045
For these gulls,
the cunning use of sound

488
00:35:27,085 --> 00:35:29,285
helps them win an easy meal.

489
00:35:34,205 --> 00:35:36,205
But in other parts of the world,

490
00:35:36,245 --> 00:35:39,725
the stakes are higher
for both predator and prey.

491
00:35:41,885 --> 00:35:43,885
(LOW GRUMBLING)

492
00:35:46,890 --> 00:35:48,885
(LOW GRUMBLING)

493
00:35:49,885 --> 00:35:51,205
(INSECTS CHIRRUPING)

494
00:35:51,245 --> 00:35:52,765
(LION GRUNTS)

495
00:35:52,805 --> 00:35:55,965
As night falls
on the African savanna,

496
00:35:56,005 --> 00:36:00,085
the air is filled
with sounds of a formidable hunter.

497
00:36:01,725 --> 00:36:03,445
(LIONS BELLOW)

498
00:36:04,765 --> 00:36:06,925
(BELLOWING CONTINUES)

499
00:36:07,965 --> 00:36:10,485
(BELLOWING)

500
00:36:11,365 --> 00:36:14,885
(DEEP RUMBLING GROWL)

501
00:36:14,925 --> 00:36:16,965
On the other side of the territory,

502
00:36:17,005 --> 00:36:20,325
the females of the pride
are preparing to hunt.

503
00:36:22,285 --> 00:36:26,405
Over 30 strong,
they must make a kill every night.

504
00:36:30,005 --> 00:36:32,005
(SOFT GROWLING)

505
00:36:32,045 --> 00:36:34,765
Close by, a hyena den.

506
00:36:34,805 --> 00:36:36,885
(SOFT SQUEAKING)

507
00:36:38,925 --> 00:36:42,845
The adults must also head out
to find their next meal.

508
00:36:47,485 --> 00:36:51,085
Hyenas will often steal
if the opportunity arises...

509
00:36:53,645 --> 00:36:56,365
..even from their deadliest foes.

510
00:36:57,605 --> 00:37:02,045
But separated from the males,
this pride is vulnerable.

511
00:37:06,285 --> 00:37:10,965
For a successful heist,
the hyenas rely on sound.

512
00:37:13,565 --> 00:37:16,325
First,
the lionesses need to make a kill.

513
00:37:16,365 --> 00:37:18,365
(GROWLING AND GRUNTING)

514
00:37:18,405 --> 00:37:21,885
With a noisy family in tow,
that can be tricky.

515
00:37:21,925 --> 00:37:23,525
(YOWLING)

516
00:37:23,565 --> 00:37:25,405
(MOOING AND GRUNTING)

517
00:37:25,445 --> 00:37:28,165
Wildebeest have gathered
together for safety.

518
00:37:28,205 --> 00:37:30,325
(MOOING AND GRUNTING)

519
00:37:34,125 --> 00:37:37,885
In the darkness,
they have to rely on their hearing.

520
00:37:40,045 --> 00:37:42,045
(DISTANT MOOING AND GRUNTING)

521
00:37:50,725 --> 00:37:53,765
The lioness
makes a stealthy approach...

522
00:38:02,765 --> 00:38:05,005
..but there is a problem

523
00:38:05,045 --> 00:38:07,445
(SNUFFLING AND RATTLING)

524
00:38:07,485 --> 00:38:11,485
A porcupine is a playful distraction
for the youngsters.

525
00:38:11,525 --> 00:38:13,245
(QUILLS RATTLE)

526
00:38:13,285 --> 00:38:16,165
The sound of shaking quills
is a warning...

527
00:38:16,205 --> 00:38:17,605
(QUILLS RATTLE)

528
00:38:17,645 --> 00:38:19,805
(SNARLING)

529
00:38:19,845 --> 00:38:21,485
(YOWLING)

530
00:38:22,245 --> 00:38:24,725
..and the wildebeest
have heard the commotion.

531
00:38:29,245 --> 00:38:31,245
(THUNDERING HOOVES)

532
00:38:35,165 --> 00:38:37,165
They have blown it for her.

533
00:38:38,965 --> 00:38:40,445
(GRUNTING AND GROWLING)

534
00:38:40,485 --> 00:38:44,325
They will take the rattle of shaking
quills more seriously next time.

535
00:38:46,285 --> 00:38:48,405
(MOOING AND GRUNTING)

536
00:38:54,365 --> 00:38:57,525
The pride
have detected another opportunity.

537
00:39:00,205 --> 00:39:02,205
A warthog burrow.

538
00:39:08,925 --> 00:39:10,085
(GROWLING)

539
00:39:10,125 --> 00:39:12,125
(WARTHOG SCREECHES)

540
00:39:12,165 --> 00:39:14,125
(SNARLING)

541
00:39:14,165 --> 00:39:16,165
(WARTHOG SCREECHES)

542
00:39:17,685 --> 00:39:19,685
(SLURPING AND CRUNCHING)

543
00:39:20,525 --> 00:39:24,925
The sound of their feast
carries far in the cool night air...

544
00:39:26,925 --> 00:39:29,325
..and the hyenas have heard.

545
00:39:30,445 --> 00:39:32,445
(CRUNCHING AND SLURPING)

546
00:39:38,205 --> 00:39:42,845
But there are too many lions here
to steal this meal alone.

547
00:39:46,925 --> 00:39:49,485
She will need the full force
of her clan.

548
00:39:50,485 --> 00:39:52,925
(LOW WHOOPING CALL)

549
00:39:52,965 --> 00:39:56,005
She sends a message
to rally her troops.

550
00:39:56,045 --> 00:39:58,045
(WHOOPING CALL)

551
00:40:02,445 --> 00:40:04,445
(WHOOPING CALL)

552
00:40:05,925 --> 00:40:09,845
Directed at the ground, her message
resonates further and faster

553
00:40:09,885 --> 00:40:11,725
than it would through air.

554
00:40:11,765 --> 00:40:13,285
(CHITTERING AND SQUEAKING)

555
00:40:13,325 --> 00:40:15,325
(CHITTERING)

556
00:40:16,725 --> 00:40:18,725
(HIGH-PITCHING SQUEAKING)

557
00:40:20,725 --> 00:40:22,165
(CHITTERING)

558
00:40:22,205 --> 00:40:24,565
Even with numbers now on their side,

559
00:40:24,605 --> 00:40:27,685
sound is critical
if they're to steal this meal.

560
00:40:27,725 --> 00:40:29,725
(WHOOPING AND CHITTERING)

561
00:40:31,325 --> 00:40:33,765
(SNARLING)

562
00:40:33,805 --> 00:40:36,205
Calling unites the clan.

563
00:40:36,245 --> 00:40:38,365
They must approach
as a tight-knit group,

564
00:40:38,405 --> 00:40:40,725
making as much noise as they can.

565
00:40:40,765 --> 00:40:43,005
(CACOPHONY OF WHOOPING AND
CHITTERING)

566
00:40:48,005 --> 00:40:49,845
(LOW GROWL)

567
00:40:49,885 --> 00:40:51,885
(HYENAS SCREECH)

568
00:40:55,365 --> 00:40:57,365
(HYENA SCREECHES)

569
00:40:59,805 --> 00:41:01,805
(LION SNARLS)

570
00:41:03,605 --> 00:41:05,125
(YELPING AND WHIMPERING)

571
00:41:05,165 --> 00:41:06,845
(SNARLS)

572
00:41:07,685 --> 00:41:09,685
(SCREECHING AND ROARING)

573
00:41:11,205 --> 00:41:14,685
The noise of the battle
has alerted more lions.

574
00:41:16,085 --> 00:41:17,445
(SNARLING)

575
00:41:17,485 --> 00:41:18,765
(FRANTIC SCREECHING)

576
00:41:19,645 --> 00:41:21,645
(YOWLING)

577
00:41:22,365 --> 00:41:23,965
(YELPING)

578
00:41:24,005 --> 00:41:25,245
(LOW GROWL)

579
00:41:25,285 --> 00:41:28,125
It's game over for the hyenas.

580
00:41:28,165 --> 00:41:30,005
(HIGH-PITCHED SCREECHING)

581
00:41:30,885 --> 00:41:32,885
The brothers have returned.

582
00:41:33,725 --> 00:41:35,965
(YELPING)

583
00:41:42,725 --> 00:41:44,725
(BIRDS TWITTERING)

584
00:41:49,885 --> 00:41:54,045
After a successful night,
the pride is well fed.

585
00:41:57,565 --> 00:42:00,125
Some will spend the day dozing.

586
00:42:03,205 --> 00:42:06,485
But for others,
it's time to reaffirm

587
00:42:06,525 --> 00:42:08,885
the prides' ownership
of their territory.

588
00:42:08,925 --> 00:42:09,965
(GROWLS HOARSELY)

589
00:42:15,005 --> 00:42:16,005
(GRUNTS)

590
00:42:23,765 --> 00:42:26,525
We are only
just beginning to understand

591
00:42:26,565 --> 00:42:29,565
the many ways that animals use sound.

592
00:42:32,485 --> 00:42:35,165
For us,
the sound of the natural world

593
00:42:35,205 --> 00:42:38,085
is a source of peace
and tranquillity.

594
00:42:40,125 --> 00:42:44,285
For other animals,
it's a tool they have to master

595
00:42:44,325 --> 00:42:47,165
in order to hunt and survive.

596
00:43:06,685 --> 00:43:09,405
MAN: Yep.
WOMAN: It is so cold out here.

597
00:43:10,245 --> 00:43:13,125
MAN: I think just over here
to the left looks pretty good.

598
00:43:13,165 --> 00:43:15,645
OK.
We have picture.

599
00:43:15,685 --> 00:43:19,245
Our film crew have come
to Manitoba in Canada

600
00:43:19,285 --> 00:43:21,565
in search of the great grey owl.

601
00:43:23,125 --> 00:43:26,925
Yeh, that looks like
a promising spot.Oh, OK.

602
00:43:27,885 --> 00:43:30,285
I think there were
some owls here last week.

603
00:43:32,125 --> 00:43:33,925
But, like many of our shoots,

604
00:43:33,965 --> 00:43:37,525
we rely on the work of others
who've come before us.

605
00:43:39,285 --> 00:43:41,845
For years, scientists have wondered

606
00:43:41,885 --> 00:43:46,645
exactly how the owl penetrates the
layers of snow that conceal its prey.

607
00:43:51,045 --> 00:43:55,085
Biologists Chris Clark and Jim Duncan
are on a mission.

608
00:43:55,125 --> 00:43:57,725
This is excellent.
There's a plunge hole right here

609
00:43:57,765 --> 00:44:00,205
where the great grey hit the snow.

610
00:44:01,845 --> 00:44:04,365
They are armed with a special tool.

611
00:44:04,405 --> 00:44:06,005
I'll grab the battery.
OK.

612
00:44:06,045 --> 00:44:08,085
An acoustic camera.

613
00:44:08,125 --> 00:44:12,165
This version
has 40 sensitive microphones

614
00:44:12,205 --> 00:44:17,685
that pinpoint sound, while a tiny
camera films its exact location.

615
00:44:18,485 --> 00:44:21,725
It should allow them to see exactly
what the owl is hearing.

616
00:44:21,765 --> 00:44:23,805
(RUSTLING)

617
00:44:23,845 --> 00:44:26,325
This camera is wonderful
because it visualises

618
00:44:26,365 --> 00:44:28,285
where the sound is coming from.

619
00:44:28,325 --> 00:44:30,325
So I'm able to look and see,

620
00:44:30,365 --> 00:44:32,765
how does the environment
affect the sound.

621
00:44:32,805 --> 00:44:34,325
(MUFFLED RUSTLING)

622
00:44:38,205 --> 00:44:40,565
Snow is a formidable barrier.

623
00:44:44,365 --> 00:44:47,845
For the vole,
it's a cloak of invisibility.

624
00:44:47,885 --> 00:44:49,405
(SNUFFLING)

625
00:44:49,445 --> 00:44:54,485
To the owl, it's an obstacle that
must be overcome by hearing alone.

626
00:44:55,645 --> 00:44:57,685
52cm?
Yeah.

627
00:44:58,845 --> 00:45:01,925
The researchers
bury a speaker under the snow

628
00:45:01,965 --> 00:45:04,645
which will play the sound
of a foraging vole.

629
00:45:04,685 --> 00:45:06,685
(HIGH-PITCHED SQUEAKING)

630
00:45:07,565 --> 00:45:09,605
They will bury it
at different depths

631
00:45:09,645 --> 00:45:13,645
and use the acoustic camera to see
how the snow affects the sound.

632
00:45:15,525 --> 00:45:17,965
The speaker is now visible
in the camera view.

633
00:45:18,005 --> 00:45:20,285
This black thing right here,
that's the speaker.

634
00:45:20,325 --> 00:45:22,845
And the acoustic camera,
that blob of colour,

635
00:45:22,885 --> 00:45:25,365
is localising the sound
coming from the speaker.

636
00:45:27,605 --> 00:45:30,205
But the playback
from the snow-covered speaker

637
00:45:30,245 --> 00:45:32,205
reveals a surprise

638
00:45:32,245 --> 00:45:36,165
- the snow dramatically alters
the location of the sound.

639
00:45:37,325 --> 00:45:41,165
(MUFFLED SQUEAKING)That metre stick
is above the speaker

640
00:45:41,205 --> 00:45:44,325
and there's a blob of colour
where the acoustic camera

641
00:45:44,365 --> 00:45:47,085
perceives the sound
to be coming out of the snow.

642
00:45:47,125 --> 00:45:51,005
It's amazing. The snow is bending
the path that the sound is taking.

643
00:45:51,805 --> 00:45:56,405
As a result, if an owl were to try
to localise the sound of the vole,

644
00:45:56,445 --> 00:46:00,285
from where it hears the sound, it
would miss and hit the wrong spot.

645
00:46:01,485 --> 00:46:05,965
But Chris realises there is a way
for the owl to overcome this problem.

646
00:46:13,005 --> 00:46:14,605
As the owl is coming in,

647
00:46:14,645 --> 00:46:17,565
it's listening to pinpoint
the location of the vole.

648
00:46:19,605 --> 00:46:22,885
Because of the snow,
it sounds like the vole is here...

649
00:46:24,205 --> 00:46:26,205
..when it's actually there.

650
00:46:28,685 --> 00:46:30,765
But as the owl gets closer,

651
00:46:30,805 --> 00:46:34,565
it starts to overcome the effect
that snow has on the sound.

652
00:46:38,285 --> 00:46:43,245
For the first time Chris realises
why, at this point in its attack,

653
00:46:43,285 --> 00:46:45,325
the great grey owl hovers.

654
00:46:46,885 --> 00:46:51,565
The acoustic camera reveals that
it's now in the perfect position.

655
00:46:53,245 --> 00:46:56,365
The sweet spot for the owl
is when it's right above the prey.

656
00:46:57,365 --> 00:47:00,405
Directly above the vole,
the snow doesn't bend the sound

657
00:47:00,445 --> 00:47:02,765
so the owl can pinpoint
exactly where the vole is.

658
00:47:04,485 --> 00:47:06,245
(SQUEAKING)

659
00:47:06,285 --> 00:47:09,085
Only then does the owl plunge.

660
00:47:10,365 --> 00:47:11,685
(VOLE SQUEAKS)

661
00:47:11,725 --> 00:47:13,085
Wow!

662
00:47:13,125 --> 00:47:16,165
It's completely amazing that
these owls can localise their prey

663
00:47:16,205 --> 00:47:17,805
just by listening.

664
00:47:22,965 --> 00:47:25,845
I love doing this kind of research
and, through that,

665
00:47:25,885 --> 00:47:28,525
understand the natural world
and the amazing things

666
00:47:28,565 --> 00:47:31,165
that species
like the great grey owl are doing.

667
00:47:33,485 --> 00:47:35,965
For decades,
researchers had believed

668
00:47:36,005 --> 00:47:40,165
that there was more to discover about
the great grey owl's acute hearing.

669
00:47:42,565 --> 00:47:45,565
Now they've finally uncovered
the complex ways

670
00:47:45,605 --> 00:47:49,365
it uses sound
to hunt its prey in snow.

671
00:47:52,565 --> 00:47:54,085
Alrighty.

672
00:47:56,285 --> 00:47:58,125
(THUNDERCLAP)
(CROAKS)

673
00:47:58,805 --> 00:48:01,285
As the story of sound continues...

674
00:48:01,325 --> 00:48:02,565
(DEEP HUMMING)

675
00:48:03,565 --> 00:48:08,245
..we reveal how animals use sound
to fight off competition...

676
00:48:08,285 --> 00:48:09,325
(WHOOPING)

677
00:48:09,365 --> 00:48:11,125
(RAPID THUDDING)

678
00:48:11,165 --> 00:48:14,645
..and use songs
in their quest to win a mate.

679
00:48:14,685 --> 00:48:16,125
(STRIDENT SQUAWKS)

680
00:48:17,805 --> 00:48:19,365
(INSECTS CHIRRUPING)

681
00:48:21,005 --> 00:48:23,005
(SOFT RUMBLING ROAR)

682
00:48:23,045 --> 00:48:25,045
(SQUAWKING AND CHIRRUPING)

683
00:48:25,085 --> 00:48:27,085
(WHOOPING CALL)

684
00:48:29,005 --> 00:48:32,165
(ANIMAL SOUNDS CONTINUE)

685
00:48:33,805 --> 00:48:35,925
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