Can Birds Still Be Heard? Assessing Song Detection in Urban Landscapes

Acoustic communication is essential for bird behavior, mediating inter- and intraspecific interactions, such as mate attraction and territory defense. These communication strategies are influenced by environmental factors including vegetation structure, microclimate, and ambient sound levels. Environmental factors affect sound propagation and the signal-to-noise ratio, which in turn impacts how far a sound can be heard by bird individuals and how effectively individuals can communicate with one another. Urban environments, however, present unique acoustic challenges for birds. Anthropogenic noise from traffic, construction, and human voices can mask natural sounds, significantly reducing the effective range of bird songs and increasing the biological costs of vocal communication. Additionally, buildings and roads alter sound transmission in various ways: while buildings can block or scatter sound waves, road corridors flanked by structures may enhance sound propagation. Although past studies have explored the impacts of human-made noise and urban structures on sound transmission, much less is understood about how these factors specifically affect the propagation of bird songs in urban landscapes. This project aims to address this knowledge gap by empirically measuring the detection range of songs from common urban bird species in Munich (Germany). We conduct controlled sound propagation experiments by broadcasting bird songs through a loudspeaker at gradually increasing distances from a recording device. By quantifying how signal characteristics and sound levels are expected to diminish with distance, and by analyzing anticipated frequency-dependent degradation using novel methods, the study aims to generate detailed propagation profiles for each species. Experiments are replicated across various urban locations that represent diverse landscape configurations, including open parks, tree-lined paths, and areas bordered by dense buildings. This approach will capture the influence of both physical structures and fluctuating human noise levels. The resulting data will contribute to new predictive models of bird song detection ranges under different urban conditions. This work is part of a broader effort to design sustainable, biodiversity-supportive urban green spaces. By enhancing our understanding of how urban infrastructure affects the transmission of natural sounds, the research will provide valuable insights for urban planners aiming to create sound environments that benefit both wildlife and human residents.