Urban Noise Threatens Dawn Chorus and Bird Populations – European researchers are increasingly concerned about accumulating evidence that urban and suburban noise is having dramatic effects on bird populations. Some birds may be adapting by developing new behaviors, perhaps changing dramatically enough to be considered new species: nightengales sing up to 14dB more loudly in the city (some at 95dB, enough to cause discomfort to human ears), great tits are singing at a higher pitch, and robins have abandoned their noisy dawn (i.e. rush hour) chorus and now sing at night, when it is quieter. Birds must hear each other in order to mate and warn each other of predators. Declining populations of house sparrows (down by two-thirds over the past couple of decades) and overall bird populations (down 20% in the past four years) could be due to difficulty in finding mates, or abandonment of urban and suburban habitat.Source: Daily Mail, 3/26/08 [READ ARTICLE]