Dominique Potvin of the University of Melbourne, Australia says: "Urban birds might be becoming genetically distinct, which is the first step towards becoming a new 'urban' species." Unlike rural areas, towns have constant background noise, as well as buildings that reflect and distort sound. Since male birds use songs to defend their territories as well as to attract females, the urban din can cramp their style. "Whether a species can survive in urban habitats depends on whether or not it can adapt acoustically," says Potvin.