Not neato, but good work by scientists for figuring it out.
A group of scientists have now shown that “Passerine Birds Breeding under Chronic Noise Experience Reduced Fitness.” Julia Schroeder of the University of Sheffield, UK, and colleagues write in their PLoS ONE article, “We found that nests in an area affected by the noise from large generators produced fewer young, of lower body mass, and fewer recruits.”
I was wondering about this just yesterday as I watched the neighborhood swallows darting about chasing insects and each other while their pip-like chirps were almost drowned out by the rush of traffic nearby. Did they have to chirp louder than normal to hear each other? Schroeder and colleagues provide some answers; see also a related BBC story, “Birds in cities ‘sing louder.'”
I also wonder how many birds are killed from traffic, noise, and loss of habitat as opposed to house cats and other predators. Anyone know of a study about that?