Behaviour 2019
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Anthropogenic noise affects song structure in a vocal mimic, the gray catbird Dumetella carolinensis
Dana L. Moseley1,2, Morgan L. Rhodes1, Jennifer C. To1, Elizabeth Neslund1, Lauren O'Brien1, Brian S. Evans2, T. Brandt Ryder2, 3. 1James Madison University, Harrisonburg, VA, United States; 2Smithsonian Migratory Bird Center, Washington, DC, United States; 3Bird Conservancy of the Rockies, Fort Collins, CO, United States

Urban noise pollution can negatively impact songbirds because low-frequency noise often masks portions of birds’ mating signals and reduces signal transmission. Previous research has demonstrated that birds in more urban habitats have song structural differences that enhance signal transmission through noise. These studies have focused mostly on species with short, stereotyped songs with limited repertoires. Gray catbirds (Dumetella carolinensis, family: Mimidae) sing long bouts containing mimicked, improvised, and invented elements – presenting a big data problem to quantify differences. We hypothesized anthropogenic noise impacts catbirds’ song structure, such as frequency, entropy, and duration. We recorded males along an urban gradient from VA to the D.C. metro region and quantified the noise level and degree of urbanization. Song minimum, maximum, and peak frequencies increased significantly as noise levels increased, demonstrating catbirds in more urban areas sing higher frequency songs likely limiting the negative effects of noise masking. These differences indicate anthropogenic noise has impacted songs of a vocal mimic similar to species with stereotyped singing styles.