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Rapid urbanization of natural habitat has led to an increase in environmental noise levels, resulting in adverse effects for wildlife. This global trend is of special concern for avian species that rely on vocal communication to defend their territories and attract mates, as low frequency anthropogenic noise produced by industrial machinery and traffic is known to mask lower frequency portions of their songs. Many bird species have been shown to adjust the frequency and/or temporal characteristics of their vocalizations in urban areas to minimize this masking effect of noise and ensure their vocalizations are heard. However, for species naturally characterized by moderate to high levels of intraspecific variation in their vocalizations, the presence of noise may also affect where individuals singing different song types choose to settle and defend territories. Song types with higher frequency components may therefore be more suited to noisier habitats and individuals singing lower frequency songs may preferentially settle in quieter areas. This study examined male Field Sparrow (Spizella pusilla) song types across an urbanization gradient to determine how song type frequencies vary within and among populations. We recorded 289 male Field Sparrows at 11 sites in southwest Michigan spanning a rural to urban gradient. We used Avisoft - SASLabPro to analyze temporal and spectral characteristics of whole songs and sweep and trill components separately. We classified songs into song types using cluster analysis and analyzed how song type frequencies varied across sites exposed to different levels of anthropogenic noise, and within sites in relation to noise sources.
Cushway, Kelsey, "The effects of anthropogenic noise on the spatial distribution of Field Sparrow song" (2019). Honors Theses. 3164.