Most species of songbirds rely on vocal communication as a vital tool for information transfer, reproduction, and survival. With recent expansions in human development and urbanization, songbirds are responding to these environmental changes. Several studies have observed developments in bird singing behavior in response to low frequency anthropogenic noise. These changes include birds singing at higher frequencies in areas of more anthropogenic noise, as well as changes in how often they sing. This study explored whether these changes occur within populations of Northern Cardinals inhabiting Vermont’s most densely populated county, Chittenden County. I quantified maximum and minimum frequencies (pitch), as well as singing rate with respect to time of day and background noise levels. The results suggest that cardinals sing at higher frequencies when anthropogenic noise levels are higher in Chittenden County, Vermont. Additionally, there was evidence to support cardinals singing at higher frequencies during later, and louder times of day within louder locations. The results of the study did not demonstrate other behavioral changes occur based on loudness as related to time of day, such as singing rate. However further testing is necessary to understand the full extent of the impacts of anthropogenic noise on Northern Cardinals in Vermont.
Read full paper here: https://scholarworks.uvm.edu/hcoltheses/475/