Evidence of suboscine song plasticity in response to traffic noise fluctuations and temporary road closures

This study investigates how noise reduction (road closure) mitigates the effect of traffic noise on the acoustic communication of the Eastern wood pewee (Contopus virens) (EAWP), a suboscine passerine. Songs were passively recorded at sites where the traffic pattern of the nearest road was either relatively constant or reduced on a weekly basis during a 36 h road closure. Five song attributes, low frequency traffic noise amplitude (LAeq) measured within 20 s of each song, and full-spectrum background noise levels (LAeq) characteristic of each territory were measured and analysed in order to better understand how EAWP respond to variation in traffic noise levels. EAWP adjusted its spectral song attributes by increasing song tonality to improve transmission in immediate response to fluctuations in traffic noise. The results suggest that song adjustments are responses to traffic noise levels at the time of their song, instead of the average background noise level measured per territory. This study provides a better understanding of how suboscine communication is affected by traffic noise, as well as the potential mitigating effect of noise reduction for animal acoustic communication.