Human-generated noise is bad for birds. For the larger species, it is worse. Birds rely on sound to find mates and avoid danger. Manmade cacophany, which is of low frequency, makes it difficult for bigger birds with low-frequency sound to hear each other’s chirps. So they are less likely to build nests in such areas. Larger birds, such as western scrub jays and pinyon jays, are important seed dispersers for trees like pines and oaks.

Source: Down To Earth, December 2011