Does ambient noise affect growth and begging call structure in nestling birds?

Much of the research examining the effects of ambient noise on communication has focused on adult birds using acoustic signals in mate attraction and territory defense. Here, we examine the effects of noise exposure on young birds, which use acoustic signals to solicit food from parents. We found that nestling tree swallows (Tachycineta bicolor) exposed to playbacks of white noise, within natural amplitude levels, from days 3 to 15 posthatch had begging calls with higher minimum frequencies and narrower frequency ranges than control nestlings raised in nests without added noise. Differences in begging call structure also persisted in the absence of noise. Two days after the noise was removed, experimental nestlings produced calls that were narrower in frequency range and less complex than control nestlings. We found no difference in growth between experimental and control nestlings. Our results suggest that long-term noise exposure affects the structure of nestling begging calls. These effects persist in the absence of noise, suggesting that noise may affect how calls develop. Copyright 2008, Oxford University Press.