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We are being replaced! Don Don MacNeill donmacneill@eastlink.ca - AN ARTICLE FOR YOU, FROM ECONOMIST.COM - AUTOMATED TWITCHING Aug 27th 2008 A new device may take the sitting around out of bird-watching ORNITHOLOGY is one of the few branches of science to which amateurs still make an important contribution. One reason is that there are lots of bird-watchers around to collect the screeds of distribution and habitat data that the science of ecology relies on. And one reason that there are so many bird-watchers (as opposed to, say, mammal-watchers) is that birds tend to advertise their presence in a way that most animals do not. Many have showy plumage, and many (not always the same ones) have mellifluous songs--meaning that a lot of bird-watching is actually bird-listening. Neither bird-watchers nor bird-listeners can be around all the time, however, so to make the process more systematic Daniel Wolff of the University of Bonn is trying to build a bird-song-recognition system that can sit in a piece of habitat and listen for the calls of particular species until its power runs out. And it seems to work. He recently conducted a trial of the system in an area of lakes to the north-east of Berlin, where it looked for Savi's warbler, a small and rare bird that loves reed beds and sounds rather like a cricket, and also for a more common species, the chaffinch. Dr Wolff programmed his system by plundering the Archive of Animal Sounds at Humboldt University in Berlin--where the calls, growls and chirrups of 110,000 species are kept. Having obtained the songs of his chosen species he applied a mathematical procedure called a Fourier transform to them. This decomposes a complex waveform into its underlying components--and a sound, however complex, is simply a wave in the air. The brain, avian or human, does something similar naturally. The result, whether performed by transistors or nerve cells, is a pattern that certainly differs from species to species and may differ from individual to individual. Dr Wolff's bio-acoustic monitor is thus quite capable of distinguishing warblers and chaffinches among the din of insects, frogs, rain and wind that constitute the auditory background of a marsh. The next task, he says, is to make the system versatile enough to program itself by recognising what is and is not birdsong, regardless of the species. If that were possible, the device could catalogue all the distinct songs it came across, chalk up the species that it recognised and signal the arrival of a bird that was not in the database if no match could be found. In that case, a search of the Humboldt archive would be in order. Which is all very good and scientific, and will undoubtedly aid an understanding of natural habitats and how they change. But romantics may be pleased to note that the human ear is still superior in some ways. Dr Wolff doubts that even his super-dooper self-programming system would be able to recognise the song of the nightingale. It is, he says, too rich. Fourier, apparently, cannot transform everything. See this article with graphics and related items at http://www.economist.com/science/tm/displaystory.cfm?story_id=11999753
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