Once confined to urban areas, anthropogenic noise is now ubiquitous, raising concerns about behavioral and distributional impacts on species. These concerns are particularly relevant for birds, due to a strong reliance on vocal communication. To date, locally scaled studies have consistently shown that most bird species decline, and some are capable of altering their vocal behavior in noisy environments. However, identification of traits that predict sensitivity to noise pollution has remained elusive.
We evaluated continental-scale breeding season associations with anthropogenic noise pollution for 323 species in the contiguous USA. We used observations from the eBird citizen-science database to model probability of occurrence for each species at a 3 km spatial resolution. We calculated average breeding season associations with noise pollution for each species weighted by probability of occurrence. Estimates of anthropogenic noise pollution were derived from sound models developed by the National Park Service. We evaluated how association with noise pollution differed among birds based on migratory behavior, breeding habitat affinity, and body mass. With 64 species having vocal trait information, we evaluated differences in song complexity, song duration, and song pitch based on body mass and breeding habitat affinity.
Results/Conclusions
Differences in life history, morphology, and vocal communication were all reflected in breeding season associations with noise pollution at the continental scale for North American breeding birds. Birds grouped by breeding habitat differed significantly in their associations with anthropogenic noise pollution (F = 53.75, p < 0.001). Forest breeding birds were associated with the lowest levels, whereas birds that breed predominantly in anthropogenic environments were associated with the highest levels. Forest and non-forest birds differed significantly in song complexity (t = -3.03, p = 0.004) but not song duration or pitch. We identified a significant nonlinear relationship between body mass and noise pollution for all birds and a significant negative association with song pitch (rho = −0.543, p < 0.001) for the subset of species with vocal trait data. There is mounting evidence that anthropogenic noise can alter community structure and function, yet it is rarely considered in conservation planning and restoration efforts. Identifying which traits best predict sensitivity to anthropogenic noise is an important step towards understanding the mechanisms driving species declines in noisy environments and will facilitate integrating effects of noise pollution into global change research.