1 00:00:03,560 --> 00:00:05,480 LOW PEEPING 2 00:00:07,680 --> 00:00:10,520 SHARP CHIRPING 3 00:00:10,520 --> 00:00:13,840 LILTING SONG 4 00:00:13,840 --> 00:00:15,800 LOW, BABBLING CALL 5 00:00:15,800 --> 00:00:18,120 HIGH, REPEATING CALL 6 00:00:18,120 --> 00:00:20,080 CHATTERING SONG 7 00:00:20,080 --> 00:00:28,000 DAWN CHORUS BUILDS 8 00:00:30,040 --> 00:00:32,480 SHRILL, WHIRLING CALL 9 00:00:32,480 --> 00:00:38,560 On a clear spring morning like this, the dawn chorus is at its peak. 10 00:00:38,560 --> 00:00:41,040 DAWN CHORUS CONTINUES 11 00:00:41,040 --> 00:00:45,880 There are surely few more enchanting natural soundscapes than this. 12 00:00:45,880 --> 00:00:49,560 DAWN CHORUS CONTINUES 13 00:00:49,560 --> 00:00:54,160 But this avian choir does not sing for us. 14 00:00:58,680 --> 00:01:03,120 These are songs of seduction and weapons of war. 15 00:01:04,520 --> 00:01:08,640 Males are defending territories and attracting mates. 16 00:01:08,640 --> 00:01:10,800 LOW CHIRPING 17 00:01:10,800 --> 00:01:12,120 COOING 18 00:01:12,120 --> 00:01:14,280 Singing is dangerous. 19 00:01:14,280 --> 00:01:15,360 CUCKOO! 20 00:01:15,360 --> 00:01:16,720 HIGH, CHATTERING SONG 21 00:01:16,720 --> 00:01:19,400 It reveals the bird's location to predators. 22 00:01:20,800 --> 00:01:23,880 But it also offers a huge reward - 23 00:01:23,880 --> 00:01:25,920 the chance to attract a female and 24 00:01:25,920 --> 00:01:29,200 pass on genes to the next generation. 25 00:01:29,200 --> 00:01:33,000 That, Charles Darwin said, is why song evolved. 26 00:01:35,040 --> 00:01:38,400 It was an example of what he called sexual selection. 27 00:01:41,960 --> 00:01:47,040 But, today, new discoveries are transforming those long-held ideas. 28 00:01:49,240 --> 00:01:50,480 For this programme, 29 00:01:50,480 --> 00:01:54,360 I've chosen some of my favourite recordings from the natural world 30 00:01:54,360 --> 00:01:57,560 that have revolutionised our understanding of song. 31 00:02:00,160 --> 00:02:02,480 There are seven recordings of it 32 00:02:02,480 --> 00:02:05,880 that have particular interest for me. 33 00:02:05,880 --> 00:02:07,520 Some are lovely, 34 00:02:07,520 --> 00:02:09,360 some are surprising, 35 00:02:09,360 --> 00:02:11,960 and one almost broke my heart. 36 00:02:11,960 --> 00:02:14,520 But all of them broke new ground. 37 00:02:14,520 --> 00:02:21,000 ANIMALS SING 38 00:02:25,040 --> 00:02:28,840 BIRDSONG, INSECTS BUZZING 39 00:02:30,800 --> 00:02:34,280 I've recorded many sounds of the natural world over the years... 40 00:02:36,040 --> 00:02:38,800 ..and I've learned that there is, perhaps surprisingly, 41 00:02:38,800 --> 00:02:41,640 no scientific definition of song. 42 00:02:44,000 --> 00:02:45,560 We tend to use the word 43 00:02:45,560 --> 00:02:49,040 to describe sounds that seem, to our ears, beautiful. 44 00:02:49,040 --> 00:02:51,640 TUNEFUL WHISTLING 45 00:02:54,080 --> 00:02:58,480 It is, in truth, a somewhat whimsical label, 46 00:02:58,480 --> 00:03:02,160 but it has been attached to some of nature's greatest marvels. 47 00:03:02,160 --> 00:03:04,800 Just listen to this. 48 00:03:04,800 --> 00:03:09,600 WHALE SONG 49 00:03:20,080 --> 00:03:25,320 Each of my seven chosen songs was recorded in my lifetime. 50 00:03:26,560 --> 00:03:27,960 BOUNCING CHIRP 51 00:03:27,960 --> 00:03:31,440 The oldest was made when I was five. 52 00:03:31,440 --> 00:03:33,960 The most recent, just a few years ago. 53 00:03:33,960 --> 00:03:37,680 CHATTERING SONG 54 00:03:37,680 --> 00:03:40,560 None is closer to my heart than the first one... 55 00:03:40,560 --> 00:03:41,960 HONKING CALLS 56 00:03:41,960 --> 00:03:45,000 ..which I made back in 1960. 57 00:03:45,000 --> 00:03:46,280 HE CHUCKLES 58 00:03:46,280 --> 00:03:51,360 WHOOPING CALLS 59 00:03:59,800 --> 00:04:03,120 Recording audio in the field in remote parts of the world 60 00:04:03,120 --> 00:04:05,600 was almost unheard of. 61 00:04:05,600 --> 00:04:10,640 There was certainly no money in the BBC budget for a sound recordist, 62 00:04:10,640 --> 00:04:14,200 but I did manage to get hold of a very rare thing indeed - 63 00:04:14,200 --> 00:04:17,360 a battery-driven portable tape recorder - 64 00:04:17,360 --> 00:04:19,840 so that I could record sounds myself. 65 00:04:22,440 --> 00:04:26,480 It was a cumbersome piece of kit, but cutting-edge at the time, 66 00:04:26,480 --> 00:04:29,760 and I was determined to use it to record a singer 67 00:04:29,760 --> 00:04:32,120 that no-one had ever recorded before. 68 00:04:33,360 --> 00:04:36,640 Madagascar's largest lemur, the indri. 69 00:04:39,280 --> 00:04:42,120 EERIE WHOOPING CALLS 70 00:04:42,120 --> 00:04:44,560 PAST ATTENBOROUGH: This noise was no bird call. 71 00:04:44,560 --> 00:04:46,960 I had never heard anything like it before. 72 00:04:46,960 --> 00:04:49,000 It must be the voice of the indris. 73 00:04:49,000 --> 00:04:53,400 CALLS CONTINUE 74 00:04:53,400 --> 00:04:55,760 PRESENT ATTENBOROUGH: Using my new equipment, 75 00:04:55,760 --> 00:04:59,040 I made the first-ever audio recording of the indri. 76 00:04:59,040 --> 00:05:02,400 CALLS CONTINUE 77 00:05:06,120 --> 00:05:09,520 But could we also capture them on camera as well? 78 00:05:11,240 --> 00:05:14,440 PAST: The song was so loud that it seemed impossible 79 00:05:14,440 --> 00:05:17,640 that the animals could be more than 20 or 30 yards away, 80 00:05:17,640 --> 00:05:19,200 but where were they? 81 00:05:19,200 --> 00:05:21,960 CALLS CONTINUE 82 00:05:21,960 --> 00:05:24,760 PRESENT: Until now, no-one had even managed 83 00:05:24,760 --> 00:05:28,720 to photograph a living one, let alone film it. 84 00:05:28,720 --> 00:05:31,400 PAST: Infuriatingly, the bush was so thick 85 00:05:31,400 --> 00:05:33,880 that I could see no sign of them, whatever. 86 00:05:33,880 --> 00:05:36,400 CALLS CONTINUE 87 00:05:36,400 --> 00:05:40,200 So the question was, how could we get close enough 88 00:05:40,200 --> 00:05:42,760 to get a clear view of them without frightening them? 89 00:05:44,280 --> 00:05:47,560 "Well," I thought, "what about doing it the other way around 90 00:05:47,560 --> 00:05:51,760 "and trying to persuade them to get closer to us 91 00:05:51,760 --> 00:05:54,000 "by playing their calls?" 92 00:05:58,880 --> 00:06:02,600 RECORDING OF INDRI CALLS PLAYS 93 00:06:02,600 --> 00:06:06,040 And they did exactly what I hoped they would do. 94 00:06:06,040 --> 00:06:11,280 RECORDING CONTINUES 95 00:06:11,280 --> 00:06:15,360 NEARBY CALLS 96 00:06:15,360 --> 00:06:18,520 They called in return, came down close to us, 97 00:06:18,520 --> 00:06:20,600 stared at us, still calling. 98 00:06:20,600 --> 00:06:23,640 INDRIS CALL 99 00:06:26,880 --> 00:06:29,360 PRESENT: I was thrilled - 100 00:06:29,360 --> 00:06:33,120 we had recorded their song and filmed them singing. 101 00:06:36,040 --> 00:06:38,720 But why had this trick worked? 102 00:06:38,720 --> 00:06:41,640 INDRI CALL 103 00:06:44,240 --> 00:06:47,040 Well, because they thought that the song I was playing 104 00:06:47,040 --> 00:06:50,240 meant a competitor was close by, 105 00:06:50,240 --> 00:06:52,720 and their response was to sing. 106 00:06:55,800 --> 00:06:59,680 And this suggested one thing. 107 00:06:59,680 --> 00:07:03,320 There are such things as battle songs. 108 00:07:03,320 --> 00:07:05,200 INDRI HOOTS 109 00:07:06,360 --> 00:07:10,560 Songs that say, "Get out, this is my territory!" 110 00:07:10,560 --> 00:07:12,640 INDRIS CALL 111 00:07:13,640 --> 00:07:17,040 GENTLE BIRDSONG 112 00:07:17,040 --> 00:07:19,240 It seemed to be a clear example 113 00:07:19,240 --> 00:07:22,480 of Darwin's theory of sexual selection. 114 00:07:24,400 --> 00:07:27,760 A male singing to defend his breeding patch. 115 00:07:29,240 --> 00:07:31,840 But this was still just guesswork. 116 00:07:34,000 --> 00:07:38,080 We suspected that songs could be weapons of war, 117 00:07:38,080 --> 00:07:41,040 but it was the next recording that proved it. 118 00:07:45,120 --> 00:07:49,120 LILTING CHIRPS 119 00:07:53,200 --> 00:07:55,200 LILTING CHIRPS 120 00:07:55,200 --> 00:07:58,760 This is the song of a male great tit. 121 00:07:58,760 --> 00:08:01,280 A call, a very simple song. 122 00:08:03,840 --> 00:08:05,880 It was recorded by a scientist 123 00:08:05,880 --> 00:08:09,400 who's been a pioneer in understanding animal song. 124 00:08:10,920 --> 00:08:12,680 Professor John Krebs. 125 00:08:14,360 --> 00:08:17,120 He was the one who proved for the first time 126 00:08:17,120 --> 00:08:20,600 exactly why my playback trick in Madagascar had worked. 127 00:08:28,120 --> 00:08:30,760 Spring 1975. 128 00:08:33,280 --> 00:08:37,480 Back then, John was a young lecturer at the University of Oxford, 129 00:08:37,480 --> 00:08:41,080 researching the birds in woodland just outside the city. 130 00:08:42,920 --> 00:08:47,280 First, he plotted the territories of all the pairs of great tits. 131 00:08:48,720 --> 00:08:52,360 Next, he recorded the songs of the males. 132 00:08:52,360 --> 00:08:56,000 REPEATING HIGH-LOW CHIRPS 133 00:08:59,120 --> 00:09:01,880 Female great tits do not sing. 134 00:09:04,400 --> 00:09:07,000 Then, on a particular morning in February, 135 00:09:07,000 --> 00:09:11,200 I came out with mist nets to catch the birds, 136 00:09:11,200 --> 00:09:14,240 and I caught all the pairs of birds that were in the woods. 137 00:09:15,560 --> 00:09:18,960 Now there were no great tits, 138 00:09:18,960 --> 00:09:21,680 just empty great tit territories. 139 00:09:21,680 --> 00:09:24,760 BIRDSONG 140 00:09:24,760 --> 00:09:29,160 In some, John replaced the great tits with loudspeakers 141 00:09:29,160 --> 00:09:34,200 that played the sounds of the birds that he had temporarily removed. 142 00:09:34,200 --> 00:09:36,600 RECORDING OF GREAT TIT SONG PLAYS 143 00:09:36,600 --> 00:09:39,120 If the song was a "keep out" signal, 144 00:09:39,120 --> 00:09:42,080 then new great tits would avoid these patches. 145 00:09:42,080 --> 00:09:46,600 RECORDING CONTINUES 146 00:09:46,600 --> 00:09:49,200 Other territories were left silent. 147 00:09:49,200 --> 00:09:52,480 No speakers, no great tit song. 148 00:09:53,600 --> 00:09:58,200 New great tits should realise these spaces were empty and available, 149 00:09:58,200 --> 00:10:00,000 and settle there quickly. 150 00:10:00,000 --> 00:10:02,680 RECORDING CONTINUES 151 00:10:02,680 --> 00:10:06,480 But how would John know that it was due to a great tit song 152 00:10:06,480 --> 00:10:08,760 that newcomers had been deterred? 153 00:10:10,680 --> 00:10:13,080 Perhaps any sound would have had the same effect. 154 00:10:14,840 --> 00:10:19,960 So, in some territories, he played a recording of a tin whistle. 155 00:10:19,960 --> 00:10:23,120 RECORDING OF TUNELESS TIN WHISTLE PLAYS 156 00:10:23,120 --> 00:10:24,640 He could have chosen anything, 157 00:10:24,640 --> 00:10:28,280 as long as it sounded nothing like a great tit. 158 00:10:28,280 --> 00:10:30,360 And then I watched to see what happened, 159 00:10:30,360 --> 00:10:32,520 and new birds came into the wood, 160 00:10:32,520 --> 00:10:34,720 because this is a prime breeding area, 161 00:10:34,720 --> 00:10:36,720 so birds love to come here to breed. 162 00:10:38,160 --> 00:10:40,240 IT CHIRPS 163 00:10:40,240 --> 00:10:43,640 John discovered that the first territories that were taken 164 00:10:43,640 --> 00:10:45,720 were the silent territories, 165 00:10:45,720 --> 00:10:47,960 and the ones with the tin whistle. 166 00:10:47,960 --> 00:10:49,800 TIN WHISTLE RECORDING CONTINUES 167 00:10:49,800 --> 00:10:53,320 Crucially, the territories in which the great tit song was played 168 00:10:53,320 --> 00:10:57,320 remained empty of new great tits. 169 00:10:57,320 --> 00:11:00,240 By looking at the detail of that pattern of settling, 170 00:11:00,240 --> 00:11:03,440 I was able to show experimentally 171 00:11:03,440 --> 00:11:06,480 that song is an effective "keep out" signal. 172 00:11:08,040 --> 00:11:11,720 THEY SING 173 00:11:11,720 --> 00:11:14,840 Professor Krebs' predictions were exactly right. 174 00:11:14,840 --> 00:11:19,760 Song was a "keep out" signal to other great tits. 175 00:11:22,720 --> 00:11:26,320 For the very first time, there was scientific evidence 176 00:11:26,320 --> 00:11:31,440 that song was being used to intimidate rivals, 177 00:11:31,440 --> 00:11:35,800 just as I had seen with the indris in Madagascar in the '60s. 178 00:11:38,040 --> 00:11:41,200 How astonishing that it was only in 1975 179 00:11:41,200 --> 00:11:44,160 that this was proved for the first time. 180 00:11:45,480 --> 00:11:48,560 The song of the great tit had made history. 181 00:11:51,720 --> 00:11:54,160 LILTING CHIRPS 182 00:11:54,160 --> 00:11:57,200 BIRDSONG 183 00:12:03,680 --> 00:12:06,000 Open a window in spring, 184 00:12:06,000 --> 00:12:08,920 and these are the singers that serenade us. 185 00:12:08,920 --> 00:12:11,360 CUCKOO! CUCKOO! 186 00:12:11,360 --> 00:12:12,720 Songbirds. 187 00:12:14,840 --> 00:12:16,520 They make up about half 188 00:12:16,520 --> 00:12:19,240 of the 10,000 species of birds in the world. 189 00:12:21,320 --> 00:12:24,840 Five of my sevens songs are sung by them. 190 00:12:28,120 --> 00:12:33,160 Birds have the most advanced vocal organs in the entire natural world. 191 00:12:33,160 --> 00:12:34,680 DEEPENING CHIRPS 192 00:12:34,680 --> 00:12:38,680 We have our voice box at the top of our windpipe, 193 00:12:38,680 --> 00:12:42,080 but their equivalent is at the base of theirs - 194 00:12:42,080 --> 00:12:44,760 it's an organ called a syrinx. 195 00:12:44,760 --> 00:12:48,400 They're the only creatures on Earth to have one of these, 196 00:12:48,400 --> 00:12:50,240 and the syrinx of the songbird 197 00:12:50,240 --> 00:12:52,640 is the most complex of them all. 198 00:12:52,640 --> 00:12:53,680 BIRD SINGS 199 00:12:53,680 --> 00:12:55,480 As breath passes through it, 200 00:12:55,480 --> 00:12:57,520 muscles contract and vibrate, 201 00:12:57,520 --> 00:13:00,160 creating the sounds we call song. 202 00:13:00,160 --> 00:13:01,840 It can produce different notes 203 00:13:01,840 --> 00:13:04,560 from the left and right sides simultaneously. 204 00:13:04,560 --> 00:13:06,320 COMPLEX BIRDSONG 205 00:13:06,320 --> 00:13:11,120 It's like having two voice boxes that can operate at the same time. 206 00:13:11,120 --> 00:13:12,920 CHATTERING SONG 207 00:13:12,920 --> 00:13:15,520 So this is how songbirds can perform 208 00:13:15,520 --> 00:13:19,720 such unparalleled feats of vocal gymnastics. 209 00:13:19,720 --> 00:13:23,400 But working out WHY they do is far more complex. 210 00:13:23,400 --> 00:13:27,440 REPEATING RASPING CHIRPS 211 00:13:27,440 --> 00:13:29,480 REPEATING BUZZING CALL 212 00:13:29,480 --> 00:13:35,240 Each note lasts just a tiny moment and then disappears. 213 00:13:35,240 --> 00:13:38,800 HIGH, BUBBLING CALL 214 00:13:38,800 --> 00:13:43,240 That presents anyone who wants to study it with a problem. 215 00:13:43,240 --> 00:13:45,520 HIGH, RAPID SONG 216 00:13:45,520 --> 00:13:48,360 But there are two relatively recent inventions 217 00:13:48,360 --> 00:13:51,000 that have helped us to capture songs. 218 00:13:51,000 --> 00:13:52,840 CHATTERING CALL 219 00:13:52,840 --> 00:13:57,800 It was with a gun mic like this, inside its windshield, 220 00:13:57,800 --> 00:14:04,000 that John Krebs caught the fleeting sound of the great tit. 221 00:14:04,000 --> 00:14:08,040 But it was the ability to take that recorded sound 222 00:14:08,040 --> 00:14:11,520 and then turn it into a visual picture 223 00:14:11,520 --> 00:14:14,560 that enabled us to analyse that sound 224 00:14:14,560 --> 00:14:16,960 and reveal its full complexity. 225 00:14:18,600 --> 00:14:19,840 LILTING GREAT TIT SONG 226 00:14:19,840 --> 00:14:23,200 This is an animation of the male great tit song, 227 00:14:23,200 --> 00:14:26,520 generated by a machine called a spectrograph. 228 00:14:28,680 --> 00:14:32,320 It changes the song into an image that's possible to read. 229 00:14:32,320 --> 00:14:33,840 DEEP CHIRPS 230 00:14:33,840 --> 00:14:38,080 Slowed down, we can see that the great tit song is relatively simple. 231 00:14:38,080 --> 00:14:39,760 CHIRPS CONTINUE 232 00:14:39,760 --> 00:14:44,360 It's composed of two notes - one high and one low - repeated. 233 00:14:45,600 --> 00:14:47,640 REPEATED HIGH CHIRPS 234 00:14:47,640 --> 00:14:49,280 What we hear is very similar 235 00:14:49,280 --> 00:14:51,360 to what we can see on the spectrograph. 236 00:14:51,360 --> 00:14:53,040 CHIRPS CONTINUES 237 00:14:53,040 --> 00:14:55,520 But compare that to the song of the male wren. 238 00:14:55,520 --> 00:14:59,000 HIGH, RAPID, COMPLEX SONG 239 00:15:00,200 --> 00:15:04,280 What we hear is not what the bird hears. 240 00:15:04,280 --> 00:15:08,240 Birds live on a different timescale, 241 00:15:08,240 --> 00:15:11,440 at a different pace from us. 242 00:15:11,440 --> 00:15:15,480 And they can hear details in their song 243 00:15:15,480 --> 00:15:19,520 that are impossible for us to hear. 244 00:15:21,400 --> 00:15:25,520 It's only when we use a spectrogram that these details are revealed 245 00:15:27,880 --> 00:15:29,200 A trill... 246 00:15:30,480 --> 00:15:33,000 ..a connecting note... 247 00:15:33,000 --> 00:15:35,200 ..another trill... 248 00:15:35,200 --> 00:15:37,800 ..and then a rapid burst of trills at the end. 249 00:15:37,800 --> 00:15:39,600 RAPID TRILLS 250 00:15:39,600 --> 00:15:42,520 Now we can see that there are perhaps 100 notes 251 00:15:42,520 --> 00:15:46,360 or more in a song that may last only a few seconds. 252 00:15:46,360 --> 00:15:48,960 RAPID TRILLS 253 00:15:48,960 --> 00:15:52,440 SLOWED, UNDULATING BIRDSONG 254 00:15:53,440 --> 00:15:55,000 RAPID TRILLS 255 00:16:02,200 --> 00:16:08,160 What the spectrograms show are these songs are far more complicated 256 00:16:08,160 --> 00:16:12,560 and complex than we could possibly have imagined. 257 00:16:12,560 --> 00:16:15,960 But why complicate things so? 258 00:16:15,960 --> 00:16:19,000 The calls of the indri and the great tit 259 00:16:19,000 --> 00:16:20,840 worked perfectly well. 260 00:16:22,080 --> 00:16:24,520 The answer, of course, is sex. 261 00:16:33,120 --> 00:16:38,320 That is the reason why so many birds have such complex mating songs. 262 00:16:38,320 --> 00:16:42,880 CHIRPS AND CHIRRUPS 263 00:16:42,880 --> 00:16:46,040 Females seem to prefer them. 264 00:16:46,040 --> 00:16:48,680 The more intricate and detailed the song is, 265 00:16:48,680 --> 00:16:51,080 the better the male's chances. 266 00:16:55,560 --> 00:16:58,640 And my third song helps to explain why. 267 00:17:01,720 --> 00:17:04,200 RHYTHMIC BIRDSONG 268 00:17:07,520 --> 00:17:12,280 It's a recording of a nightingale that is my next chosen song. 269 00:17:12,280 --> 00:17:15,520 NIGHTINGALE SINGS 270 00:17:15,520 --> 00:17:19,000 This is a male singing for a mate. 271 00:17:20,600 --> 00:17:25,360 Just as with the great tit, the females do not sing. 272 00:17:25,360 --> 00:17:29,160 But they are the ones the males are singing for. 273 00:17:29,160 --> 00:17:31,960 So why do they prefer more complex songs? 274 00:17:38,920 --> 00:17:42,920 It's a question that has puzzled scientists for centuries. 275 00:17:45,280 --> 00:17:48,400 Charles Darwin's answer was that the females 276 00:17:48,400 --> 00:17:51,120 have an aesthetic sense. 277 00:17:51,120 --> 00:17:54,280 After all, human beings appreciate beauty. 278 00:17:54,280 --> 00:17:56,960 Why shouldn't other animals do so too? 279 00:17:59,200 --> 00:18:02,680 But the question Darwin didn't answer was 280 00:18:02,680 --> 00:18:06,200 WHY should the females have an aesthetic sense? 281 00:18:08,560 --> 00:18:12,800 Here on the streets of Berlin, we might just find the answer. 282 00:18:15,960 --> 00:18:21,680 Spring attracts over 2,000 nightingales to this city each year. 283 00:18:21,680 --> 00:18:25,560 They flock to Berlin because it's filled with green space, 284 00:18:25,560 --> 00:18:28,880 much of which has been left untamed. 285 00:18:28,880 --> 00:18:32,320 And it's these wild places that they love. 286 00:18:36,200 --> 00:18:40,960 In one of its most popular parks, a male nightingale. 287 00:18:44,120 --> 00:18:48,280 He, like the other males, arrived from Africa a few weeks ago 288 00:18:48,280 --> 00:18:52,200 and has spent his time singing to defend a breeding patch. 289 00:18:54,280 --> 00:18:59,520 But tonight, when the lights go out, he will change his tune 290 00:18:59,520 --> 00:19:02,360 because the females have arrived. 291 00:19:02,360 --> 00:19:06,000 RAPID CHIRPS 292 00:19:07,440 --> 00:19:12,160 Nightingales migrate at night, and when the females fly in, 293 00:19:12,160 --> 00:19:16,400 under cover of dark, they are met with songs of seduction. 294 00:19:16,400 --> 00:19:21,440 COMPLEX TWEETS, TRILLS AND CHIRPS 295 00:19:26,760 --> 00:19:32,200 Dr Conny Landgraf made our recording of the nightingale's song. 296 00:19:37,440 --> 00:19:41,280 So right now, there's one... Oh, no there is a second male. 297 00:19:41,280 --> 00:19:45,000 So it's already two males in a vocal contest. 298 00:19:47,000 --> 00:19:51,760 What the females do is that they do not take the first male that comes 299 00:19:51,760 --> 00:19:57,160 their way, but they prospect and inspect different male territories. 300 00:19:57,160 --> 00:19:59,600 And this is like a speed dating that is actually 301 00:19:59,600 --> 00:20:01,680 going on in the middle of the night. 302 00:20:01,680 --> 00:20:04,240 OVERLAPPING BIRDSONGS 303 00:20:04,240 --> 00:20:08,800 Each male sings his heart out and the females listen. 304 00:20:09,840 --> 00:20:11,040 DING 305 00:20:11,040 --> 00:20:12,240 Time's up! 306 00:20:12,240 --> 00:20:15,080 What does the next potential mate sound like? 307 00:20:15,080 --> 00:20:17,440 DING Time's up again. 308 00:20:17,440 --> 00:20:19,840 Does the next one have a better song? 309 00:20:19,840 --> 00:20:21,360 QUICKFIRE CHIRPS 310 00:20:21,360 --> 00:20:22,560 DING 311 00:20:25,880 --> 00:20:33,040 Nightingales have extremely large song repertoires, up to 250 songs. 312 00:20:33,040 --> 00:20:38,360 And also they are able to produce really challenging 313 00:20:38,360 --> 00:20:43,720 syllables and phrases, thinking of trill or bass elements. 314 00:20:43,720 --> 00:20:47,280 So these are very fast, repeated single notes. 315 00:20:47,280 --> 00:20:49,040 So this is remarkable. 316 00:20:50,400 --> 00:20:53,480 The more complex his song, 317 00:20:53,480 --> 00:20:56,280 the more beautiful it seems to the female. 318 00:20:57,520 --> 00:21:00,760 But why? Does the female have an aesthetic sense, 319 00:21:00,760 --> 00:21:03,560 as Darwin suggested? 320 00:21:03,560 --> 00:21:08,000 Conny and her team set up an experiment to find out. 321 00:21:08,000 --> 00:21:12,760 First, they recorded males singing at the beginning of spring. 322 00:21:13,800 --> 00:21:17,520 Then they set up cameras to record nightingale nests 323 00:21:17,520 --> 00:21:19,280 later in the season. 324 00:21:21,600 --> 00:21:25,760 Male nightingales play a crucial role in feeding chicks. 325 00:21:31,880 --> 00:21:35,280 What we found in the end was that there was indeed 326 00:21:35,280 --> 00:21:38,360 a very strong correlation between his song 327 00:21:38,360 --> 00:21:40,800 and feeding rates at the nest. 328 00:21:40,800 --> 00:21:44,720 So it's like a promise that the males give to the females 329 00:21:44,720 --> 00:21:46,160 to be good fathers. 330 00:21:49,000 --> 00:21:51,800 So, for example, a male could be saying, 331 00:21:51,800 --> 00:21:54,840 "Hey, there, I'm a healthy, strong man, 332 00:21:54,840 --> 00:21:59,200 "I know this area and all the best feeding places very well, 333 00:21:59,200 --> 00:22:02,120 "so come settle down and mate with me." 334 00:22:06,400 --> 00:22:10,480 Females, Darwin said, chose the males with the most beautiful 335 00:22:10,480 --> 00:22:15,320 songs, and my third recording has demonstrated why. 336 00:22:15,320 --> 00:22:17,680 Better singers are better fathers. 337 00:22:19,440 --> 00:22:22,920 Songs can be a promise of devoted parenthood. 338 00:22:36,480 --> 00:22:39,720 There are some songs that it's impossible for me 339 00:22:39,720 --> 00:22:42,840 to imagine life without. 340 00:22:42,840 --> 00:22:44,800 ROBIN SINGS 341 00:22:44,800 --> 00:22:47,680 Songs that accompany our daily lives. 342 00:22:49,680 --> 00:22:52,720 It's one of the most characteristic sounds, and to my ear 343 00:22:52,720 --> 00:22:55,960 is one of the most delightful of the English winter - 344 00:22:55,960 --> 00:22:58,080 the song of the robin. 345 00:23:02,280 --> 00:23:04,480 These are the songs that Charles Darwin 346 00:23:04,480 --> 00:23:06,080 would have listened to as a boy. 347 00:23:07,240 --> 00:23:12,000 And much of our research into song has centred on British species. 348 00:23:14,000 --> 00:23:17,720 Indeed, for much of the last century, we thought birdsong 349 00:23:17,720 --> 00:23:20,400 originated here in northern latitudes. 350 00:23:23,200 --> 00:23:27,920 But what if Darwin had been raised on the other side of the world? 351 00:23:27,920 --> 00:23:30,720 Would his theories about song have been different? 352 00:23:32,720 --> 00:23:35,960 CACOPHONY OF ANIMAL CALLS 353 00:23:35,960 --> 00:23:38,400 The forests of Australia. 354 00:23:45,360 --> 00:23:48,760 Out here, scientists are in the process of changing 355 00:23:48,760 --> 00:23:51,440 many of our old ideas about song. 356 00:23:52,960 --> 00:23:55,480 HOOTING CRY 357 00:23:56,720 --> 00:24:01,000 They found fossil and DNA evidence of early songbirds, 358 00:24:01,000 --> 00:24:04,200 which show that this, in fact, is where song began. 359 00:24:09,320 --> 00:24:12,320 It was here in Australia that the ancestors 360 00:24:12,320 --> 00:24:15,320 of all songbirds first evolved. 361 00:24:23,880 --> 00:24:27,960 Song number four is from one of the original songbirds' 362 00:24:27,960 --> 00:24:30,000 most remarkable descendants. 363 00:24:31,640 --> 00:24:35,360 And it's one that amazes me every time I hear it. 364 00:24:35,360 --> 00:24:40,280 QUIZZICAL WHISTLES 365 00:24:41,920 --> 00:24:46,200 It was recorded in the forests just outside Melbourne, 366 00:24:46,200 --> 00:24:49,440 and it was the first time that wild birdsong had ever 367 00:24:49,440 --> 00:24:51,520 been broadcast in Australia. 368 00:24:52,760 --> 00:24:54,360 BIRD CALLS 369 00:24:58,280 --> 00:25:02,720 The song of the lyrebird, in my view, is one of the most complex 370 00:25:02,720 --> 00:25:06,960 and beautiful in the whole of the natural world. 371 00:25:06,960 --> 00:25:09,640 And what gives it its complexity 372 00:25:09,640 --> 00:25:12,680 is the talent that a lyrebird has 373 00:25:12,680 --> 00:25:13,880 for mimicry. 374 00:25:16,080 --> 00:25:17,520 ON RECORD: Crimson parrot. 375 00:25:17,520 --> 00:25:19,600 BIRD CALLS 376 00:25:22,000 --> 00:25:24,040 The kookaburra. 377 00:25:24,040 --> 00:25:25,520 BIRD CALLS 378 00:25:27,680 --> 00:25:30,840 The descendants of that lyrebird, I'm happy to say, 379 00:25:30,840 --> 00:25:33,600 are still singing in those forests, 380 00:25:33,600 --> 00:25:36,440 and I've been lucky enough to listen 381 00:25:36,440 --> 00:25:38,040 to one of them myself. 382 00:25:39,520 --> 00:25:45,560 It was the 1990s when the BBC series Life Of Birds took me to Australia. 383 00:25:48,640 --> 00:25:53,240 I wanted to film a lyrebird who was the most astounding mimic. 384 00:25:56,960 --> 00:26:00,800 To persuade females to come close and admire his plumes, he sings 385 00:26:00,800 --> 00:26:03,240 the most complex song he can manage, 386 00:26:03,240 --> 00:26:06,640 and he does that by copying the songs of all the other birds 387 00:26:06,640 --> 00:26:08,000 he hears around him, 388 00:26:08,000 --> 00:26:09,640 such as the kookaburra. 389 00:26:11,600 --> 00:26:13,240 KOOKABURRA CALL 390 00:26:14,440 --> 00:26:18,520 He can imitate the calls of at least 20 different species. 391 00:26:22,040 --> 00:26:26,080 He also, in his attempt to out-sing his rivals, incorporates other 392 00:26:26,080 --> 00:26:29,040 sounds that he hears in the forest. 393 00:26:29,040 --> 00:26:30,320 CLICKING 394 00:26:30,320 --> 00:26:32,080 That was a camera shutter. 395 00:26:38,200 --> 00:26:39,720 And again. 396 00:26:43,280 --> 00:26:45,480 And now a camera with a motor drive. 397 00:26:47,120 --> 00:26:48,960 CLICK AND WHIR 398 00:26:48,960 --> 00:26:51,000 ALARM BLARES 399 00:26:52,920 --> 00:26:54,640 And that's a car alarm. 400 00:27:03,600 --> 00:27:08,240 And now the sounds of foresters and their chainsaws working nearby. 401 00:27:08,240 --> 00:27:10,320 BUZZING 402 00:27:13,520 --> 00:27:15,240 SAWING 403 00:27:16,680 --> 00:27:20,360 Since this remarkable clip was broadcast, millions of people 404 00:27:20,360 --> 00:27:22,040 have watched it online. 405 00:27:24,120 --> 00:27:27,960 Scientists have discovered a lot more about lyrebird song 406 00:27:27,960 --> 00:27:30,200 since that recording was made. 407 00:27:30,200 --> 00:27:34,800 That particular bird was accustomed to the presence of human beings 408 00:27:34,800 --> 00:27:39,320 nearby, but much wilder birds produce something 409 00:27:39,320 --> 00:27:40,960 even more fascinating. 410 00:27:43,160 --> 00:27:46,320 Sunrise, Sherbrooke Forest, today. 411 00:27:48,720 --> 00:27:50,880 One voice in the dawn chorus 412 00:27:50,880 --> 00:27:54,760 is louder than any other - the male lyrebird. 413 00:27:58,400 --> 00:28:00,400 BIRD CALLS 414 00:28:03,040 --> 00:28:07,560 It's the breeding season and they're busy trying to attract mates. 415 00:28:14,200 --> 00:28:17,320 Clearing undergrowth from the forest floor creates 416 00:28:17,320 --> 00:28:19,760 an arena for his mating display. 417 00:28:27,680 --> 00:28:30,720 Once the stage is set, the show can begin. 418 00:28:32,800 --> 00:28:36,000 CALLING 419 00:28:36,000 --> 00:28:38,760 It's unlike any other in the natural world. 420 00:28:42,080 --> 00:28:43,960 Since I heard this song, 421 00:28:43,960 --> 00:28:47,680 scientists have analysed it and broken it down into parts. 422 00:28:51,840 --> 00:28:54,480 Song A comes first. 423 00:28:54,480 --> 00:28:56,640 CLICKS AND WHISTLES 424 00:29:00,160 --> 00:29:06,040 Now song B, a loud low shriek, which alternates with song C, 425 00:29:06,040 --> 00:29:08,480 a quiet, very soft clicking sound. 426 00:29:16,480 --> 00:29:18,640 A female arrives. 427 00:29:20,640 --> 00:29:22,080 But no, she loses interest. 428 00:29:25,920 --> 00:29:29,800 What he does next will need to be even more impressive. 429 00:29:40,360 --> 00:29:44,240 Few have analysed the grand finale of the male lyrebird song 430 00:29:44,240 --> 00:29:48,960 more intensively than Dr Anastasia Dalziell. 431 00:29:48,960 --> 00:29:53,120 She and her team were the first ones to film it properly. 432 00:29:54,600 --> 00:29:58,040 We thought no-one's going to believe us until we've actually filmed it. 433 00:29:58,040 --> 00:30:02,320 It's really not like anything else that has been described previously 434 00:30:02,320 --> 00:30:04,520 in birds or any other animals. 435 00:30:08,520 --> 00:30:11,760 It was by studying the recordings from their remote camera 436 00:30:11,760 --> 00:30:14,720 that the team were able to understand the real secret 437 00:30:14,720 --> 00:30:16,920 of the male lyrebird song. 438 00:30:18,480 --> 00:30:22,560 And it's this footage together with our own that enables us to show 439 00:30:22,560 --> 00:30:26,400 this remarkable behaviour on television for the first time. 440 00:30:28,480 --> 00:30:32,760 Having sung A, B and C and been rejected, the male now 441 00:30:32,760 --> 00:30:34,000 begins Song D. 442 00:30:35,200 --> 00:30:37,080 So this final song, 443 00:30:37,080 --> 00:30:41,960 it's the sound of a flock of small birds mobbing, 444 00:30:41,960 --> 00:30:46,280 reacting to a stationary or a hidden predator like a snake. 445 00:30:46,280 --> 00:30:48,920 And this was totally bizarre. 446 00:30:48,920 --> 00:30:52,080 So why is he imitating a flock of birds? 447 00:30:53,720 --> 00:30:55,960 Well, a predator means danger. 448 00:30:55,960 --> 00:30:59,800 So at the sound of an alarm call, the female freezes. 449 00:31:04,640 --> 00:31:07,240 The forest is no longer a safe place. 450 00:31:11,000 --> 00:31:14,760 Now the male takes advantage of her panic. 451 00:31:14,760 --> 00:31:17,080 He jumps on top of her to mate. 452 00:31:19,760 --> 00:31:22,600 It's hard for us to see her under his feathers, 453 00:31:22,600 --> 00:31:25,600 and it's hard for her to see out from under them. 454 00:31:27,040 --> 00:31:31,480 He's doing everything he can to disorientate and confuse her. 455 00:31:36,360 --> 00:31:39,080 The male is actually telling her a big fib - 456 00:31:39,080 --> 00:31:41,880 don't leave me because out there, there's a hidden predator 457 00:31:41,880 --> 00:31:43,520 that you haven't seen. 458 00:31:43,520 --> 00:31:46,000 To put it another way, it's like saying, 459 00:31:46,000 --> 00:31:47,960 "Baby, it's dangerous outside. 460 00:31:47,960 --> 00:31:51,400 "Come back here with me where it's nice and safe." 461 00:31:55,080 --> 00:31:59,240 The lyrebird is, in fact, a bird that tells lies. 462 00:32:01,000 --> 00:32:03,520 His song is an acoustic illusion. 463 00:32:05,600 --> 00:32:07,600 Up to now, scientists have thought 464 00:32:07,600 --> 00:32:10,400 that song was an honest signal from the male. 465 00:32:11,560 --> 00:32:17,000 But it seems song can also be manipulative and false. 466 00:32:31,040 --> 00:32:35,080 scientist Victoria Austin is studying the female lyrebird. 467 00:32:38,960 --> 00:32:40,800 What she's listening for 468 00:32:40,800 --> 00:32:43,400 is something very few people have heard. 469 00:32:44,480 --> 00:32:47,480 So what I'm doing now is just preparing my recorder 470 00:32:47,480 --> 00:32:51,760 because we're about to head to a nest and we're hoping to be able 471 00:32:51,760 --> 00:32:54,600 to record the female lyrebird that resides in that area. 472 00:32:57,240 --> 00:33:01,240 The female lyrebird is the opposite of her flashy mate. 473 00:33:01,240 --> 00:33:02,640 She's secretive. 474 00:33:05,160 --> 00:33:09,000 When she is seen, she's often mistaken for a juvenile male. 475 00:33:11,240 --> 00:33:14,680 To most people, she's invisible, 476 00:33:14,680 --> 00:33:17,120 but Victoria knows how to find her. 477 00:33:19,800 --> 00:33:23,800 This old nest suggests that she may be nearby. 478 00:33:24,880 --> 00:33:26,360 And there she is. 479 00:33:27,880 --> 00:33:31,920 This rarely heard sound is her whistle song. 480 00:33:31,920 --> 00:33:33,760 CALLING 481 00:33:37,560 --> 00:33:40,120 In Darwin's theory of sexual selection, 482 00:33:40,120 --> 00:33:45,200 males sing to attract females, and females drive the evolution 483 00:33:45,200 --> 00:33:48,400 of song by preferring ever more complex songs. 484 00:33:50,240 --> 00:33:53,720 The females themselves do not sing. 485 00:33:53,720 --> 00:33:57,720 Yet here we are listening to a female lyrebird singing. 486 00:34:00,360 --> 00:34:03,040 So what is the function of her song? 487 00:34:06,480 --> 00:34:09,440 Well, the female raises her chicks alone. 488 00:34:12,520 --> 00:34:17,280 The male plays no part, so it's extremely important 489 00:34:17,280 --> 00:34:20,720 for her to maintain her territory and the food within it. 490 00:34:22,160 --> 00:34:26,600 She uses song to let everyone know that it's her patch. 491 00:34:26,600 --> 00:34:28,400 CALLING 492 00:34:31,600 --> 00:34:34,120 And Victoria is also researching 493 00:34:34,120 --> 00:34:36,760 whether song helps her in other ways. 494 00:34:38,200 --> 00:34:41,240 In the last few years, she's been recording their songs 495 00:34:41,240 --> 00:34:43,160 across the Blue Mountains. 496 00:34:47,760 --> 00:34:52,320 This is one of them - a female mimicking a goshawk. 497 00:34:52,320 --> 00:34:54,160 BIRDSONG 498 00:34:59,080 --> 00:35:00,400 It's very accurate. 499 00:35:00,400 --> 00:35:03,480 If you were to play this call alongside an actual goshawk, 500 00:35:03,480 --> 00:35:05,880 it'd be very difficult to tell the difference, if you were able 501 00:35:05,880 --> 00:35:08,480 to tell the difference at all. 502 00:35:08,480 --> 00:35:12,080 So what is the purpose of this perfect impersonation? 503 00:35:14,360 --> 00:35:18,560 She's using it to deceive predators into thinking she's more dangerous 504 00:35:18,560 --> 00:35:20,240 than she actually is. 505 00:35:25,600 --> 00:35:29,120 She is just as talented as the more famous male. 506 00:35:32,240 --> 00:35:35,480 So the biggest purpose of what we're doing working 507 00:35:35,480 --> 00:35:40,720 with these female lyrebirds is to dispel this long-held myth that only 508 00:35:40,720 --> 00:35:42,800 recently was shown not to be true, 509 00:35:42,800 --> 00:35:45,800 and that is the idea that female birds don't sing, 510 00:35:45,800 --> 00:35:47,240 or that it's very rare. 511 00:35:47,240 --> 00:35:49,600 And that's just simply not the case. 512 00:35:52,760 --> 00:35:57,240 This surely challenges Darwin's theory, 513 00:35:57,240 --> 00:36:00,440 as does my next revolutionary song. 514 00:36:08,800 --> 00:36:12,000 My fifth song was also recorded in Australia. 515 00:36:14,080 --> 00:36:18,920 It, too, like the song of the female lyrebird, has rarely been heard. 516 00:36:21,600 --> 00:36:26,240 It's important because its existence changes our idea 517 00:36:26,240 --> 00:36:28,080 of what song actually is. 518 00:36:29,800 --> 00:36:31,720 BIRDSONG 519 00:36:33,840 --> 00:36:38,200 This is a fairly common Australian bird called a fairy wren. 520 00:36:42,600 --> 00:36:46,840 We filmed these birds for a BBC series back in the 1990s. 521 00:36:51,240 --> 00:36:56,120 We went there to film it because it's extremely promiscuous. 522 00:36:56,120 --> 00:37:00,520 Both male and female will mate with many different partners. 523 00:37:01,600 --> 00:37:06,160 But what few people realised at the time, and I certainly didn't, 524 00:37:06,160 --> 00:37:09,840 was that it's not just the male that sings. 525 00:37:12,400 --> 00:37:14,040 The female does, too. 526 00:37:20,360 --> 00:37:23,760 This is Canberra Botanical Gardens. 527 00:37:25,560 --> 00:37:28,640 Professor Naomi Langmore was the scientist 528 00:37:28,640 --> 00:37:31,120 who made our fairy wren recording. 529 00:37:32,240 --> 00:37:36,800 She was one of the first to realise the significance of female song. 530 00:37:40,760 --> 00:37:44,880 The male fairy wren, with glorious, iridescent blue and striking 531 00:37:44,880 --> 00:37:47,640 black plumage is rather difficult to miss. 532 00:37:51,120 --> 00:37:52,760 So where is the female? 533 00:37:53,800 --> 00:37:57,280 Well, not at the top of a perch like the male, 534 00:37:57,280 --> 00:38:00,080 but instead here, hiding in the bushes. 535 00:38:02,480 --> 00:38:06,680 She is comparatively rather dull - a drab brown. 536 00:38:07,880 --> 00:38:12,080 Because females are often less flashy and eye-catching than males, 537 00:38:12,080 --> 00:38:14,920 it's very easy to miss female song. 538 00:38:14,920 --> 00:38:17,520 BIRDSONG 539 00:38:17,520 --> 00:38:19,360 But sing she does. 540 00:38:22,640 --> 00:38:26,120 Just as male song is used in competition with other males, 541 00:38:26,120 --> 00:38:30,120 female song seems to be in competition with other females. 542 00:38:31,600 --> 00:38:34,840 But why didn't we hear her before now? 543 00:38:34,840 --> 00:38:39,320 Is it really just because she's less noticeable than the male? 544 00:38:39,320 --> 00:38:41,320 In the history of the study of birdsong, 545 00:38:41,320 --> 00:38:44,600 most research was done in the northern hemisphere, in Europe 546 00:38:44,600 --> 00:38:47,000 and North America, and in those regions, 547 00:38:47,000 --> 00:38:49,280 female song is comparatively rare. 548 00:38:49,280 --> 00:38:52,720 And so researchers working in those regions generalised 549 00:38:52,720 --> 00:38:55,960 from what they were observing in their local birds and assumed 550 00:38:55,960 --> 00:38:59,600 that male song was the norm throughout the world. 551 00:38:59,600 --> 00:39:02,360 A male-biased view of birdsong had, 552 00:39:02,360 --> 00:39:05,440 to an extent, deafened us to female song. 553 00:39:06,720 --> 00:39:10,000 So when I was doing my research, it was basically assumed 554 00:39:10,000 --> 00:39:13,640 that it's the male that sings and the female doesn't. 555 00:39:13,640 --> 00:39:16,280 Maybe that's because most of the scientists were males 556 00:39:16,280 --> 00:39:17,720 who were studying birdsong. 557 00:39:17,720 --> 00:39:20,960 But now there's a new generation of female scientists coming through 558 00:39:20,960 --> 00:39:24,600 studying birdsong all around the world 559 00:39:24,600 --> 00:39:28,040 and discovering that actually female song is very common 560 00:39:28,040 --> 00:39:30,280 and occurs in more species than not. 561 00:39:31,480 --> 00:39:34,440 And it's only now that they're properly being heard. 562 00:39:36,080 --> 00:39:40,120 Naomi and her colleagues have discovered that in 64% 563 00:39:40,120 --> 00:39:44,080 of all songbird species, females sing. 564 00:39:45,160 --> 00:39:47,240 And that, in the distant past, 565 00:39:47,240 --> 00:39:49,600 the ancestors of all songbirds 566 00:39:49,600 --> 00:39:53,000 would have had both male and female singers. 567 00:39:57,640 --> 00:40:02,160 When birdsong began, perhaps all female birds sang. 568 00:40:05,640 --> 00:40:08,440 So why don't all female birds sing today? 569 00:40:10,320 --> 00:40:12,200 The answer is migration. 570 00:40:14,160 --> 00:40:18,440 Male migrants like the nightingale arrive in their breeding grounds 571 00:40:18,440 --> 00:40:22,720 before the female. They set up and defend the breeding 572 00:40:22,720 --> 00:40:26,000 territories, so the females don't need to sing. 573 00:40:28,600 --> 00:40:32,440 In species that don't migrate, like the lyrebird and fairy wren, 574 00:40:32,440 --> 00:40:35,280 then often the females will have their own territory. 575 00:40:39,480 --> 00:40:41,360 And they will sing to defend it. 576 00:40:45,000 --> 00:40:49,080 This female song challenges the way scientists have thought about 577 00:40:49,080 --> 00:40:52,080 sexual selection for the last hundred years. 578 00:40:53,200 --> 00:40:55,480 This recent discovery is a paradigm shift. 579 00:40:55,480 --> 00:40:57,320 It's extremely exciting, 580 00:40:57,320 --> 00:40:59,480 and it really forces us again 581 00:40:59,480 --> 00:41:03,080 to reconsider what we think of as birdsong. 582 00:41:05,160 --> 00:41:08,760 Birdsong was fundamental to the formulation of Darwin's theory 583 00:41:08,760 --> 00:41:10,240 of sexual selection, 584 00:41:10,240 --> 00:41:13,000 and the discovery that females sing as well 585 00:41:13,000 --> 00:41:15,200 makes us challenge that theory. 586 00:41:16,920 --> 00:41:20,640 Because our perception of birdsong has been biased 587 00:41:20,640 --> 00:41:23,080 towards the northern hemisphere, 588 00:41:23,080 --> 00:41:27,680 we have been unaware of some of the most thrilling bird songs 589 00:41:27,680 --> 00:41:30,520 on the planet, but that view is changing. 590 00:41:34,920 --> 00:41:38,320 Our understanding of song is continually developing, 591 00:41:38,320 --> 00:41:40,960 and all the time we're learning new things. 592 00:41:40,960 --> 00:41:45,200 It's a mystery that needs real research to unravel it, 593 00:41:45,200 --> 00:41:47,160 and we're still learning. 594 00:41:49,240 --> 00:41:52,880 How exciting it is to think of the discoveries 595 00:41:52,880 --> 00:41:55,480 that are about to be made about birdsong. 596 00:42:06,240 --> 00:42:10,640 This next ground-breaking recording reminds us just how thrilling 597 00:42:10,640 --> 00:42:12,920 those new discoveries could be... 598 00:42:14,920 --> 00:42:19,480 ..because it revealed to us an entirely different world of song. 599 00:42:23,760 --> 00:42:29,240 Few animal songs are more beautiful than the ones that are recorded 600 00:42:29,240 --> 00:42:34,520 on this disc, and yet had it not been for recent technological 601 00:42:34,520 --> 00:42:38,840 advances, we would never have known that such songs existed. 602 00:42:42,120 --> 00:42:44,800 The waters off the coast of Bermuda. 603 00:42:45,920 --> 00:42:50,000 US Navy engineers are using underwater microphones called 604 00:42:50,000 --> 00:42:53,600 hydrophones to listen for enemy submarines. 605 00:42:55,000 --> 00:42:57,080 This is what they pick up. 606 00:42:58,080 --> 00:43:00,480 LOW GROWLING 607 00:43:02,640 --> 00:43:06,920 It's not a submarine or indeed any kind of man-made noise. 608 00:43:10,880 --> 00:43:15,000 I'll always remember the first time I heard those songs. 609 00:43:16,600 --> 00:43:19,800 It brought back to my mind the stories of sailors 610 00:43:19,800 --> 00:43:21,720 in the old sailing ship days 611 00:43:21,720 --> 00:43:23,480 out at sea in their bunks, 612 00:43:23,480 --> 00:43:27,560 hearing those wonderful, eerie sounds resonating through the ship. 613 00:43:29,240 --> 00:43:33,040 It didn't come, of course, from a mermaid, but something perhaps 614 00:43:33,040 --> 00:43:38,080 even more extraordinary - a gigantic creature weighing many tonnes. 615 00:43:38,080 --> 00:43:39,120 A whale. 616 00:43:40,720 --> 00:43:42,480 WHALE SONG 617 00:43:47,360 --> 00:43:52,080 Almost unbelievably, this was the first time that anyone had ever 618 00:43:52,080 --> 00:43:54,520 identified the sound of a whale. 619 00:43:56,800 --> 00:44:00,240 When biologist Dr Roger Payne heard it, he was thrilled. 620 00:44:02,080 --> 00:44:07,680 It was back in 1967 about that I met a fellow named Frank Watlington, 621 00:44:07,680 --> 00:44:09,440 who became a great friend, 622 00:44:09,440 --> 00:44:12,600 and he played a sound to me of humpback whales. 623 00:44:13,960 --> 00:44:15,920 WHALE SONG 624 00:44:15,920 --> 00:44:20,520 It was the most beautiful thing I had ever heard from nature. 625 00:44:29,320 --> 00:44:34,000 The first time I ever went swimming with a whale that was singing, 626 00:44:34,000 --> 00:44:38,440 it's such an incredible experience, it's completely shattering. 627 00:44:41,760 --> 00:44:45,560 It feels like, when you get close to one, that something 628 00:44:45,560 --> 00:44:48,360 has put its hands on your chest and is shaking you 629 00:44:48,360 --> 00:44:50,280 until your teeth rattle. 630 00:44:50,280 --> 00:44:53,680 My first thought was, I wonder if I can stand this, I wonder 631 00:44:53,680 --> 00:44:56,920 if this is actually going to kill me somehow. 632 00:45:01,280 --> 00:45:05,160 The question was, would we call these sounds songs? 633 00:45:08,080 --> 00:45:10,280 Some were short, like birdcalls, 634 00:45:10,280 --> 00:45:11,760 but others were longer, 635 00:45:11,760 --> 00:45:13,560 some up to half an hour. 636 00:45:20,120 --> 00:45:23,520 Speeded up, this is what they sounded like. 637 00:45:23,520 --> 00:45:25,760 HIGH-PITCHED SONG 638 00:45:29,120 --> 00:45:31,440 They sounded like birdsong. 639 00:45:34,320 --> 00:45:36,280 Roger called them songs. 640 00:45:44,080 --> 00:45:48,480 In the late 1970s, I too went swimming with humpback whales. 641 00:45:51,520 --> 00:45:55,880 I remember seeing this creature below me and then hearing its song. 642 00:45:55,880 --> 00:45:58,120 EERIE WHOOPING 643 00:46:01,320 --> 00:46:05,880 It was thought they sing for the same reason as birds - 644 00:46:05,880 --> 00:46:09,480 males singing to rivals and potential mates. 645 00:46:11,560 --> 00:46:14,600 But no-one has ever seen a female listening. 646 00:46:17,240 --> 00:46:20,640 In truth, no-one really knows why whales sing. 647 00:46:24,080 --> 00:46:28,720 But one thing is certain - the sound of their song saved them from us. 648 00:46:31,320 --> 00:46:36,200 In 1970, Roger released an album called Songs Of The Humpback Whale. 649 00:46:37,880 --> 00:46:41,000 At the time, we had been killing whales, 650 00:46:41,000 --> 00:46:43,000 mainly for their oil, for centuries. 651 00:46:47,640 --> 00:46:51,840 We were very close to exterminating them out of sheer greed. 652 00:46:53,600 --> 00:46:55,600 Then we heard their song. 653 00:47:00,200 --> 00:47:05,240 Whole bunches of people in several countries began making organisations 654 00:47:05,240 --> 00:47:09,560 to save the whales and the Save the Whales movement was born, 655 00:47:09,560 --> 00:47:12,320 and in many ways that was sort of the beginning 656 00:47:12,320 --> 00:47:14,400 of the conservation movement. 657 00:47:19,520 --> 00:47:23,560 The conscience of the world was woken by this song of the whale. 658 00:47:25,160 --> 00:47:27,880 We heard it just in time to save them. 659 00:47:27,880 --> 00:47:29,720 ECHOING SHRIEK 660 00:47:32,520 --> 00:47:35,240 But for my next and final singer, 661 00:47:35,240 --> 00:47:37,320 there was no such reprieve. 662 00:47:39,200 --> 00:47:40,680 BIRDSONG 663 00:47:46,120 --> 00:47:50,200 There are few songs more haunting than this. 664 00:47:56,280 --> 00:48:01,320 It's a male Hawaiian 'o'o bird calling for a mate. 665 00:48:04,280 --> 00:48:06,600 But is he singing into silence? 666 00:48:08,680 --> 00:48:09,880 Habitat destruction 667 00:48:09,880 --> 00:48:13,960 and the introduction of invasive species have decimated 668 00:48:13,960 --> 00:48:17,800 many Hawaiian songbirds, including the 'o'o. 669 00:48:19,480 --> 00:48:23,960 It may well be that by the time this recording was made, 670 00:48:23,960 --> 00:48:26,640 there were no females left alive. 671 00:48:27,960 --> 00:48:33,840 It's the sound of a male singing for a mate who no longer exists. 672 00:48:36,480 --> 00:48:39,920 The 'o'o has since been declared extinct. 673 00:48:43,440 --> 00:48:48,280 He was the last of an entire bird family found nowhere else on Earth. 674 00:48:48,280 --> 00:48:49,760 Now gone. 675 00:48:52,920 --> 00:48:58,600 There is no more dramatic reminder of this loss than this sound. 676 00:48:58,600 --> 00:49:00,640 BIRDSONG 677 00:49:13,480 --> 00:49:17,640 And how many more songs have we lost in other parts of the planet? 678 00:49:19,960 --> 00:49:24,040 Here in Britain, it's estimated that 38 million birds 679 00:49:24,040 --> 00:49:28,280 have disappeared from our skies in the last 60 years. 680 00:49:28,280 --> 00:49:30,680 One in five gone. 681 00:49:34,160 --> 00:49:37,240 Climate change, habitat deterioration 682 00:49:37,240 --> 00:49:40,800 and the resulting decrease in food and other resources 683 00:49:40,800 --> 00:49:43,080 are thought to be the main factors 684 00:49:43,080 --> 00:49:45,360 behind this catastrophic decline. 685 00:49:47,400 --> 00:49:50,840 It's now up to us to decide how many more songs 686 00:49:50,840 --> 00:49:51,960 we will allow 687 00:49:51,960 --> 00:49:53,440 to fade into silence. 688 00:50:03,400 --> 00:50:06,920 These songs enrich our lives, too. 689 00:50:06,920 --> 00:50:11,200 They're surely amongst the loveliest in the universe. 690 00:50:11,200 --> 00:50:16,920 And without them, our lives would truly be impoverished. 691 00:50:16,920 --> 00:50:21,720 And what is lost when the songs fall silent is more than just 692 00:50:21,720 --> 00:50:26,560 an enchanting operatic backdrop to our own lives, 693 00:50:26,560 --> 00:50:31,600 because for the creatures that sing them, songs are far more than that. 694 00:50:33,400 --> 00:50:35,160 They are a weapon of war... 695 00:50:36,400 --> 00:50:40,800 ..a serenade, a promise of parenthood, a daring deceit... 696 00:50:42,960 --> 00:50:45,920 ..or perhaps something even more astonishing 697 00:50:45,920 --> 00:50:47,920 that we are yet to discover. 698 00:50:49,760 --> 00:50:54,520 Each one a marvellous example of the spectacular survival strategies 699 00:50:54,520 --> 00:50:57,920 that animals have developed in order to stay alive. 700 00:50:57,920 --> 00:50:59,920 WHALE SONG 701 00:50:59,920 --> 00:51:02,520 That is why I'll never cease to wonder at 702 00:51:02,520 --> 00:51:04,120 the beautiful sounds 703 00:51:04,120 --> 00:51:05,880 we call song. 704 00:51:08,000 --> 00:51:09,880 CHIRPING 705 00:51:29,160 --> 00:51:32,800 Few sounds of nature are more beloved by this nation 706 00:51:32,800 --> 00:51:35,560 than that of the nightingale. 707 00:51:35,560 --> 00:51:38,600 And there's one more recording of it that I have memories 708 00:51:38,600 --> 00:51:40,520 of listening to as a child. 709 00:51:41,760 --> 00:51:47,440 It was made by the BBC two years before I was born, in May 1924. 710 00:51:48,560 --> 00:51:53,120 It's a cello accompanied by a nightingale. 711 00:51:53,120 --> 00:51:55,960 In this country, it was ground-breaking. 712 00:51:58,840 --> 00:52:04,720 It is, in fact, the first live broadcast of any wild animal song. 713 00:52:10,800 --> 00:52:15,480 The idea came from a celebrated cellist called Beatrice Harrison. 714 00:52:17,920 --> 00:52:21,720 RECORDING: One night when I'd been playing for hours, 715 00:52:21,720 --> 00:52:24,800 I suddenly heard the note 716 00:52:24,800 --> 00:52:28,320 of the most heavenly bird, 717 00:52:28,320 --> 00:52:33,040 and it struck me how lovely it would be if he could be broadcast. 718 00:52:36,640 --> 00:52:40,880 The nation held its breath while Beatrice played. 719 00:52:40,880 --> 00:52:45,160 It was the first time that the wild world of nature 720 00:52:45,160 --> 00:52:47,320 came straight into your living room. 721 00:52:51,120 --> 00:52:55,480 Perhaps a million listeners tuned in to that first broadcast. 722 00:52:59,000 --> 00:53:03,040 It was so popular, the BBC made it an annual event. 723 00:53:05,880 --> 00:53:10,800 The performance became so celebrated that Beatrice was asked to recreate 724 00:53:10,800 --> 00:53:14,240 it for a 1943 film with Sir Laurence Olivier. 725 00:53:14,240 --> 00:53:16,360 CELLO PLAYS 726 00:53:19,320 --> 00:53:21,080 BIRD CALLS 727 00:53:28,360 --> 00:53:31,760 It was far from the first time, of course, that the nightingale 728 00:53:31,760 --> 00:53:34,040 had made a cultural appearance. 729 00:53:35,280 --> 00:53:41,000 The nightingale has inspired poets and musicians for ages, and perhaps 730 00:53:41,000 --> 00:53:45,440 the most famous poem of all is by John Keats. 731 00:53:46,720 --> 00:53:50,360 Thou was not born for death, immortal Bird! 732 00:53:50,360 --> 00:53:54,280 No hungry generations tread thee down, 733 00:53:54,280 --> 00:53:58,240 The voice I hear this passing night was heard 734 00:53:58,240 --> 00:54:01,480 In ancient days by emperor and clown. 735 00:54:03,520 --> 00:54:08,000 Keats wrote those lines in Hampstead in London, 736 00:54:08,000 --> 00:54:11,440 but he wouldn't hear a nightingale there today. 737 00:54:17,960 --> 00:54:20,800 There are no nightingales in London now. 738 00:54:22,120 --> 00:54:26,480 In fact, we've lost over 90% of nightingales in this country 739 00:54:26,480 --> 00:54:28,320 in the last 50 years. 740 00:54:31,560 --> 00:54:32,760 What a tragedy. 741 00:54:36,240 --> 00:54:39,000 The causes are still not fully understood... 742 00:54:40,920 --> 00:54:45,280 ..but habitat deterioration probably played a significant part. 743 00:54:51,480 --> 00:54:55,160 In one small corner of Britain, however, there is a place trying 744 00:54:55,160 --> 00:54:58,240 to provide the nightingale with a safe haven. 745 00:54:59,800 --> 00:55:06,080 The Knepp Estate in West Sussex - 3,500 acres that was once farmland. 746 00:55:08,120 --> 00:55:12,400 But the soil here wasn't suited to modern-day intensive agriculture. 747 00:55:13,840 --> 00:55:17,280 Since 2001, it's been left to nature. 748 00:55:19,880 --> 00:55:24,960 There aren't many rewilding projects in Britain as pioneering as this. 749 00:55:28,800 --> 00:55:30,680 Wildlife now thrives here... 750 00:55:34,960 --> 00:55:38,200 ..including some of the country's rarest species. 751 00:55:43,840 --> 00:55:46,320 CUCKOO CALL 752 00:55:46,320 --> 00:55:49,960 This, for many of Britain's best-loved songbirds, 753 00:55:49,960 --> 00:55:53,000 is an ideal place for shelter and food. 754 00:55:58,920 --> 00:56:02,960 The nightingale is one of many species found at Knepp. 755 00:56:04,800 --> 00:56:08,440 Here, dense, almost impenetrable thorny scrub 756 00:56:08,440 --> 00:56:10,880 provides their ideal nesting site. 757 00:56:16,800 --> 00:56:21,440 Today, it's late spring and one nest of chicks is being ringed. 758 00:56:25,000 --> 00:56:28,760 This makes it possible to gather vital information that can help 759 00:56:28,760 --> 00:56:30,560 monitor population numbers. 760 00:56:34,880 --> 00:56:38,480 There are estimated to be more than 40 nightingale territories 761 00:56:38,480 --> 00:56:40,360 in this area of the estate. 762 00:56:44,360 --> 00:56:46,840 Back when it was intensively farmed, 763 00:56:46,840 --> 00:56:48,680 there were only nine. 764 00:56:49,880 --> 00:56:52,920 Few places in Britain have nightingales increasing 765 00:56:52,920 --> 00:56:54,200 in such numbers. 766 00:56:58,640 --> 00:57:02,080 It gives us hope, perhaps, that the British countryside 767 00:57:02,080 --> 00:57:05,320 could once more be filled with the nightingale's 768 00:57:05,320 --> 00:57:07,840 beautiful and iconic song. 769 00:57:13,880 --> 00:57:19,640 How wonderful it would be if each of us could say we've heard the songs 770 00:57:19,640 --> 00:57:23,200 of the Earth and we've saved them. 771 00:57:23,200 --> 00:57:25,440 BIRDSONG 772 00:57:32,320 --> 00:57:34,360 WHALE SONG 773 00:57:51,600 --> 00:57:54,880 BIRD AND WHALE SONG