P2.9 Thursday, Jan. 5 Effects of anthropogenic noise on song sparrow song DE JESUS, Carrie E*; HOESE, William; California State University Fullerton; California State University Fullerton email@example.com
Song sparrow (Melospiza melodia) males use songs for territorial defense and mate attraction. These acoustic signals may be masked by anthropogenic noise thereby reducing their effectiveness. Avian species reduce the effects of masking by changing when they sing to times with reduced noise, singing more frequently, singing louder, and shifting lower frequencies upward. Previous studies on song sparrows found that the minimum frequency was higher in males in noisy locations compared with males in quieter locations. We compared the songs of males singing in a high-noise location (adjacent to a 12 lane highway) with those of males in a low-noise location (undeveloped riparian habitat) in southern California to determine if all songtypes in a repertoire were similarly shifted in the noisy location. We hypothesized that song sparrows in noisy sites would have songs with higher minimum frequencies and narrower bandwidths compared to song sparrows in quieter sites. Repertoires from five males each in noisy and quiet sites were recorded during the spring of 2010 and 2011. Recordings were made with a Marantz PMD661 solid state recorder and Sennheiser condenser microphone. Ambient noise levels at each location were measured with a sound pressure level meter. We identified songtypes and measured the following characteristics from five songs from each songtype: minimum frequency, maximum frequency, and bandwidth. Sites varied with levels of anthropogenic noise: high 65 dBa (±SD 4.59), and low noise 45 dBa (±SD 5.01). Songs from the noisy site had a significantly higher minimum frequency than songs from the quiet site. There were no significant differences for maximum frequency or bandwidth between sites. Our findings provide additional evidence that individuals modify their vocal production in response to anthropogenic noise.