Anthropogenic noise weakens territorial response to intruder's songs

Noise pollution degrades natural acoustic conditions, potentially interfering with bird communication. However, exactly how noise impacts the ability of the signal receiver to detect and discriminate vocalizations from conspecifics remains understudied in field settings. We performed a natural experiment to determine the effect of noise pollution on the territorydefense behaviors of two emberizid sparrows exposed to carefully constructed playbacks of conspecific intruder songs. Although all birds reacted to the playbacks, response latency increased with noise levels. This suggests that noise interferes with signal reception and may indicate impaired signal discrimination. We place these results in the context of a receiver’s “listening area” and the significant impact of noise pollution on this receivercentric perceptual acoustic range. This work informs conservation efforts and provides a much needed fieldbased examination of the disruptive impact of noise pollution on behaviors directly related to reproduc-