Effects of noise on avian abundance and productivity at the landscape scale

Abstract

Songbirds, with their reliance on acoustic communication, may be especially sensitive to potential population consequences of anthropogenic noise. Regional studies suggest that many species avoid noisy areas, and in some cases non-avoiding individuals experience reduced fitness. However, multiple studies of a species sometimes produce conflicting results, perhaps due to localized processes that overpower or exacerbate noise effects. Many studies also use abundance as an imperfect proxy for population persistence. To address these issues, we paired large published datasets—from the MAPs (Monitoring Avian Productivity and Survivorship) program and the U.S. National Parks Service noise map—to assess noise levels and bird demographics across the continental United States. We modeled effects of noise on songbird diversity, abundance, productivity, and physical condition (fat score), accounting for temporal and spatial variation. At the continental scale, diversity decreased with increasing noise, but other effects varied by species. For example, least flycatchers become more abundant with increasing noise, and red-breasted nuthatches less abundant. Effects on fat and productivity also varied by species, with abundance trends not consistently matching productivity. Landscape-scale models such as those presented here may facilitate range-wide conservation measures and help identify species or groups that are most at risk.