City Song: Birds sing higher near urban traffic

City songbirds that stake out territories near loud traffic tend to pitch their songs at higher frequencies than do birds in quieter neighborhoods, Dutch researchers have found.

Recordings of a common European species, the great tit (Parus major), showed a higher minimum frequency in the noisier parts of Leiden, says Hans Slabbekoorn of Leiden University. In the loudest places, engine roars overlapped the lower frequencies of the tits' songs, Slabbekoorn and his Leiden colleague Margriet Peet report in the July 17 Nature.