Urban Bioacoustics - It's Not Just Noise
 
P. Warren, M. Katti, and M. Ermann

 
The acoustic environment plays a major role in shaping animal communication systems. Humans, particularly in cities, profoundly alter the acoustic structure of their environment. Several recent articles have identified effects of noise on animal communication and behaviour. These studies, however, serve to highlight the surprising dearth of research on the behavioural responses of animals to altered acoustic environments. We argue that noise level is not the only aspect of urban bioacoustics that researchers should explore. In addition to elevated noise levels, urban areas are characterized by a predominance of linear rather than point sources of noise, many vertical reflective surfaces, and, predictable diurnal variation in noise levels and sound transmission. All of these characteristics have parallels in natural environments. This suggests that cities are a fruitful area for future research on the evolution of animal communication systems, with implications for conservation in human-altered environments more generally. We present and illustrate a conceptual overview of the acoustic properties of urban areas as well as pilot data from studies conducted in Phoenix, Arizona.
 

 
Keywords: bioacoustics, noise, birds, animal communication, built structure