Environmental noise influences song frequency of Yellow Warblers (Dendroica petechia) in Grand Teton National Park

We explored how Yellow Warblers (Dendroica petechia) alter their songs when encountering noise in Grand Teton National Park. Different strategies for avoiding signal masking are used by other species of birds, yet there is a lack of information of birds’ responses to higher noise levels -- above 65 dB; such levels are often found in National Parks that have many visitors. In this study, we investigated singing behavior of Yellow Warblers when facing noise that ranged from 30 dB to 80 dB. In these preliminary results, we found that some features of Yellow Warblers did not appear to change with background noise level, including mean minimum frequency, bandwidth and song length. Other song features we studied did show small but statistically significant changes with higher background noise, including the peak frequency and the mean minimum frequency, both of which were significantly negatively correlated with the level of background noise. This result is different from the positive correlations that are typically observed.  We speculate that this difference is due to the very high dB levels of background noise that we observed.   Featured photo by wagon16 on Flickr. https://flic.kr/p/G2W6Bk