How traits affect bird responses to anthropogenic noise - a meta-analysis

Abstract

Anthropogenic noise is a consequence of the expansion of humans across the globe. It has been labeled as a pollutant and threatens the health of not only humans, but wildlife as well. Birds are at an increased risk of being negatively affected by anthropogenic noise because of their reliance on acoustic information. Research has shown that noise can impact different aspects of bird behavior (e.g., foraging) and have negative consequences on their fitness (e.g., reproduction). Exploring how ecological and life-history traits make a species more, or less, vulnerable to anthropogenic noise is important to mitigating the negative impacts of this pollutant. We performed a meta-analysis to explore how birds varied in their responses to anthropogenic noise. We then explored how traits contribute to a variety of responses most directly related to fitness (physiology, reproduction, and growth). We found that species traits mediated the affects of noise on birds. Anthropogenic noise more negatively affected the physiology (e.g., stress hormones) and growth (e.g., body mass) of bird species with larger body sizes and that vocalized at a lower frequency. Several other traits including nesting height, nest type, foraging height, and song range were also predictive of growth responses to anthropogenic noise. Birds with open nests and with nests closer to the ground were found to have their growth more negatively affected. In addition, birds that fed mainly between 2m above the ground to canopy level and that had a wider song frequency range were found to have their growth more negatively affected. We did not find any traits to be related to reproductive responses but did see differences in responses among noise types. Industrial noises (e.g., resource extraction) had the most negative affect on reproductive responses. Our research indicates that the impacts of noise vary among responses and species. Birds are at risk of experiencing decreases in fitness due to anthropogenic noise, but more research is needed to determine how anthropogenic noise affects communities and populations.