Everyone who has been in a major city knows how much noise it can produce. Trucks and cars roaring by, planes flying over, people calling on their phones…and so on.
All this ruckus creates lots of noise, which is generally of a pretty low frequency/tone. The problem is, lots of birds also use these same tones, so when they want to sing in a city, their songs cannot be heard by other birds due to so-called ‘auditory masking’. However, obviously we still have some birds in the city. How do they get around the problem?
Hans Slabbekoorn and Margriet Peet, two researchers from the Netherlands, show that great tits (Parus major), adjust their songs by producing more high pitched sounds than they normally would, in order to be heard in the city, giving the first example that human activity changes the song of birds.
Does this mean that the noise doesn’t matter, considering the birds found a solution? Not at all, there is evidence that birds in cities do less well than birds outside of the city due to the noise, so we would do well to reduce the amount of noise we create.
Slabbekoorn, H. & Peet, M. 2003. Birds sing at a higher pitch in urban noise. Nature 424, 267.