Songs to raise the dodo from the dead: Mike Gerrard finds out how computers can re-create the calls of extinct birds

BY 1907 the huia bird from New Zealand had sung its last song. The species became extinct because man encroached on its habitat in the forests and mountains of the North Island, introducing disease and predators. It was a beautiful bird with a metallic green/black plumage, white-tipped tail feathers, orange wattles on its cheeks and a long ivory-coloured bill. Paintings exist, but no photographs or recording of its song. Now, thanks to one man and his Macintosh computer, it is once again possible to listen to the sound of the huia.

Until he took early retirement in 1985, David Hindley had been head of music at Homerton College, Cambridge, for 23 years. Since then, he has devoted himself to the study of the musical qualities of birdsong, a field he has almost to himself.

'The majority of people dealing with birdsong are scientists, who look at it from a totally different angle,' he says. 'Scientists are always concerned with facts, and so conjecture or art is anathema to them. As soon as a musician begins to talk about birdsong in terms of beauty and value and so on, he is viewed with suspicion.'

Yet Mr Hindley's painstaking studies of recordings - analysing two and a half seconds of a single chaffinch's song and re-creating it on his synthesiser can take several weeks - show that there is considerable variation even within a bird's most recognisable call. We can tell a robin from a chaffinch, but a chaffinch can distinguish between other chaffinches. Some birds even have regional accents.

'How can a female recognise the male,' Mr Hindley asks, 'unless there's something about the quality of the male's song which makes it different from the others? In a small, localised environment, the songs of chaffinches will be very similar, but there will none the less be distinct differences, just as your voice is different from mine. The further you go away from a certain environment, the bigger the differences. The range of difference from a chaffinch at John O'Groats to a chaffinch at Land's End is quite considerable.'

Mr Hindley says that we cannot hope to understand the behaviour of birds until we have a fuller understanding of their sounds. We do break these down into mating calls, territorial calls and so on, yet what we regard as one territorial call may in fact be conveying several distinct messages.

None of this work would have been possible before the advent of the computer. A bird such as the skylark can make 200 sounds per second, and the song needs to be slowed down 16 times before each discrete note can be heard and analysed. One minute of birdsong takes up 10 megabytes of storage space, which is why Mr Hindley now has a 240-megabyte hard disc and still finds it too small.

He began modestly, with an Amstrad PCW, before graduating to a Macintosh. He now uses the Finale program on a Macintosh FX, linked to a Yamaha FY-77 synthesiser.

This combination produced the call of the huia for Lifesong, a collection of recordings of threatened bird species. The idea for the project came from the International Council for Bird Preservation as a way of drawing attention to the birds the world is in danger of losing. These include the Seychelles magpie robin, of which only about 20 exist, and the whooping crane, hunted down to its current population of just more than 100. The world has lost the songs of more than 100 bird species in the last 300 years, and today more than 1,000 species are threatened.

So how did Mr Hindley re-create the sound of a bird that became extinct before the technology was available to record it? The New Zealand Broadcasting Corporation sent him two recordings of elderly Maori trackers made in the Fifties, on which they imitated the song of the huia as they remembered it from their youth. There were also written descriptions, comparing the song to other New Zealand birds that still exist. These helped Mr Hindley create a haunting track, which lasts for five minutes and sets the huia's song against a background of other forest birds, such as the bellbird and grey warbler.

It is very different from the sound he was asked to create for last month's edition of the children's programme The Really Wild Show - the call of the dodo.

'That really was a fantasy,' he says. 'There's nothing in the literature that gives any description of the bird's song. There was one reference to a cry, which wasn't at all helpful, so all I could go on was that the bird was a pigeon. That got me listening to cooing sounds, to the turtle dove and birds of that kind. Then I thought that the dodo's large size would probably lower the pitch. I listened to other pigeon sounds - the barbary dove, particularly, which has quite a manic song, with a screaming sound in the middle of it - and thought perhaps the dodo might scream, too. It also had this huge bill, which it shed every year, rather like deer shed their antlers. Deer get rid of their antlers by rutting and fighting, and I thought that dodos would probably hit anything in sight and bash stones to get rid of their bills, so I included lots of percussive sounds as well. No one can say I'm wrong, because no one knows any better.'

The five minutes of the huia's song and the few seconds of the dodo's each took Mr Hindley several months of research. But his is not a well-rewarded activity. 'I get something like 0.5 per cent royalty on the Lifesong tape, which won't amount to very much. The small fee for The Really Wild Show didn't even cover the time involved in researching it. In fact,' he admits, 'what I'm getting is peanuts.'

'Lifesong' is available on CD ( pounds 12.99) and cassette ( pounds 8.99) from ManKind Music, 32 Aldridge Villas, London W11 1BW (p & p pounds 1 UK, pounds 2.50 overseas), with 10 per cent of proceeds going to ICBP conservation work.

(Photograph omitted)