Meeting Abstract
Vocal responses to anthropogenic noise have been documented in a growing number of songbird species. It is important to understand whether these song adjustments are primarily proximate changes reflecting developmental plasticity and/or behavioral flexibility, or longer-term ultimate consequences of selection on vocal performance. Few studies have investigated these differences. Furthermore, human noise pollution is often accompanied by structural changes to the habitat, including the introduction of noisy roadways and the removal of native vegetation. To date, no studies have simultaneously investigated the impact of both acoustic and structural disturbance on the same species. The relevance of each of these variables must be quantified if we wish to refine our understanding of the ways in which human activities influence avian communication via noise pollution. We report a study of breeding eastern bluebirds (Sialia sialis) that quantifies both among- and within-male song adjustments in response to ambient noise, and also investigated whether anthropogenic habitat modifications explained variations in song parameters. We found that males in noisier sites produced both higher-pitched and louder songs than birds in quieter areas. Likewise, individual males demonstrated immediate adjustments to noise disturbance, increasing their song amplitude between periods of quiet and loud ambient noise. Both spectral and temporal aspects of a male’s song were related to whether his habitat was more ‘natural’ or ‘anthropogenic.’ These results indicate that male song adjustments may represent simultaneous and flexible responses to multiple human habitat modifications. We suggest that human habitats provide an ideal setting in which to perform ‘natural experiments’ on animal behavior and cognition.
