LONDON - Sing high, sing fast. This is what songbirds have to do to survive in the din of city life, a study has found.
Scientists say in the latest Current Biology that songbirds living in forests sing more slowly and in lower frequencies than their cousins whohave opted for an urban lifestyle.
The study was carried out on great tits living in 10 European cities and in 10 nearby forests. Scientists analysed the way the birds used songs to attract mates and establish territorial boundaries.
"Birds sing faster in the cities compared with forests. The forest birds sing low and they sing slow," said Hans Slabbekoorn, of Leiden University in the Netherlands.
Great tits living in noisy cities have to compete with the low-frequency sounds of heavy traffic which means that their own songs go up in pitch to make themselves heard.
City birds sing faster because they deliberately shorten the first notes of each song compared with their forest cousins. Dr Slabbekoorn said this appeared to be the result of differences in average wind speed between the two types of habitat.
In forests, air turbulence is much lower on average than in relatively open urban areas. The lower turbulence means the birds can afford to sing long first notes, which do not get distorted.
The study was carried out in major cities, including London, Nottingham, Amsterdam, Paris, Brussels and Prague, and could help to explain why some wild birds avoid urban life.
The capacity of great tits to sing within a relatively wide frequency range, and the ability to adjust their songs by leaving out lower frequencies, seems to be critical to their ability to thrive in cities. It could also explain why some birds disappear while others increase.
