Birds in Cities

The helter-skelter of urban life even affects birds. I swear my cockatiel is better behaved since I left London; now I know why:

Rapid urbanisation around the world and the subsequent increase in ambient noise has proven problematic for animals which use sound to communicate. For birds in particular, city noises can mask the exchange of vital information and prevent males from attracting mates.

To see how birds reacted to increased noise, Hans Slabbekoorn of Leiden University recorded the songs of great tits in 10 European cities including London, Prague, Paris and Amsterdam. He then compared the songs with birds of the same species in nearby forests. The results, published today in the journal Current Biology, showed that songs important in attracting mates and defending territory were markedly different in the urban setting.

"The songs diverged in several parameters," said Dr Slabbekoorn. "In 10 out of 10 comparisons we found that birds in cities use a higher minimum frequency. The songs in cities are faster, especially the duration of the first element of each of those repetitive song phrases."

He explained the change as a response to increased low frequencies in cities, such as traffic noise.