EVERY bird sings a different tune. Crows caws, chickadees whistle and hermit thrushes add a flute-like flourish. But can software identify each one even against busy background noise?
Timos Papadopoulos and colleagues at the University of Oxford are developing an algorithm to do just that.
Such algorithms could be a boon to conservationists, who regularly journey out on foot or in helicopters to tally up the number of birds living in a given area. If, instead, audio recordings could be converted into species counts, it would be easier to track whether a particular bird is in decline or changing its migration patterns.
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聯If recordings could be converted into species counts, we could track bird populations more easily聰
Bird sounds are tricky to sort through, says Dan Stowell at Queen Mary University of London. For one thing, we don鈥檛 know what the birds are saying, while recordings tend to be noisy and distant.
鈥淭here are 12 birds in a tree somewhere rather than one person talking into a microphone,鈥� Stowell says. 鈥淭hat鈥檚 what makes it a really interesting challenge.鈥�
To develop the tool, the Oxford team collected recordings of 15 different bird species found around Europe and Asia, including the common nightingale, the great tit and the song thrush. They blended recordings with different audio environments: in one case, the gentle background noise of an urban park; in another, the din of an open air market, dense with city sounds and people鈥檚 voices.
These mash-ups were used to train a machine learning algorithm to identify birdsong from distracting backgrounds. It fared less well for a few species with songs that are closer in frequency to the city noise ().
Other groups are working on their own bird algorithms, especially those that can identify different species. Stowell and his colleagues are testing an app called Warblr that tells different songs apart and is due to launch later this year. A team at the University of Wisconsin at Madison developed a similar app called WeBIRD, designed for local birds. And the Merlin app, developed at the Cornell Lab of Ornithology, helps citizens identify a bird they have spotted by asking a few simple questions about its size, colour and location.
An algorithm like the Oxford team鈥檚 could be a valuable addition, since data recordings taken in the wild can be bogged down with uninteresting sections, says Mario Lasseck of the Animal Sound Archive at the Natural History Museum in Berlin, Germany. Lasseck is an entrant in this year鈥檚 BirdCLEF competition to be held in Toulouse, France, in September to create automatic bird-classifying algorithms based on audio alone.
鈥淚f you have data from a forest where the bird was just singing for five minutes then it鈥檚 very useful to find out where these five minutes are,鈥� Lasseck says.
This article appeared in print under the headline 鈥淎sk the auto twitcher鈥�
