"The fast pace of city-life affects all urbanites - even the feathered ones. Dutch researchers Hans Slabbekoorn and Ardie den Boer-Visser of Leiden University studied the songs of the great tit, a forest-dwelling bird that has adapted well to urban life, in the middle of ten major European cities. They compared the songs to those of great tits living in nearby forest sites, and found that the city-dweller's songs were markedly shorter, faster and higher-pitched than those of forest birds. The difference, Slabbekoorn says, can be explained by the constant low-frequency noise, such as the roar of traffic, with which city birds must compete.
This adaptability is good news for great tits, but according to Slabbekoorn, birds whose songs do not change will be at a real disadvantage in city settings. "The same set of urban species becomes more and more common in all cities, he says, " and traffic noise may well play an important role in this loss of diversity."