Canopy porosity mediates foraging behaviors in songbirds in the presence of anthropogenic noise pollution, Pellston Plains, MI (2025)

Anthropogenic noise pollution is an increasingly prevalent environmental stressor that can modulate animal behavior. Noise pollution alters acoustic landscapes, influencing behavior that relies on acoustic stimuli. Traffic noise is a considerable source of anthropogenic noise, and the behavioral effects on songbirds may be influenced by forest structure through attenuation and the alteration of sound propagation. We experimentally exposed songbirds visiting feeders to recorded traffic noise across forest habitats that varied in vegetation structure and canopy porosity. Using replicated feeder trials and LiDAR-derived measures of forest structure, we quantified foraging and vigilance behaviors before, during, and after noise exposure and analyzed responses using linear mixed-effects models. Traffic noise exposure did not significantly alter foraging or vigilance behavior across species. In contrast, forest structure significantly influenced behavior, with increased canopy vegetation associated with reduced foraging and increased vigilance during limited phases of the trials, particularly during early morning periods. Results indicate that habitat structure, rather than short-term traffic noise exposure, was the primary driver of behavioral variation in this system. Attenuation caused by canopy vegetation density and porosity may outweigh the behavioral effects of traffic noise, highlighting the importance of structural habitat features in shaping responses to anthropogenic sound.