Social factors, not anthropogenic noise or artificial light, influence onset of dawn singing in a common songbird

With worldwide increases in artificial light and anthropogenic noise, understanding how these pollutants influence animals allows us to better mitigate potential negative effects. Both light and noise affect the timing of daily activities, including the onset of dawn song in birds, yet the influence of these pollutants compared with social factors that also influence song onset remains unknown. We investigated the onset of dawn song, testing hypotheses aimed at understanding the influences of light and noise pollution as well as male competition, pairing status, and breeding stage on timing of dawn singing by male House Wrens (Troglodytes aedon). Overall, models with social factors fit song onset data better than models with abiotic factors of noise and sky glow, and the highest ranking model included nesting stage, number of male neighbors, and temperature. Males began singing earlier when they were building nests and when mates were fertile than during later nesting stages. Males also sang earlier as the number of male neighbors increased. The timing of dawn song by male House Wrens appeared unaffected by day-to-day variation in light and noise pollution, with social factors having larger effects on the onset of daily behavior in this species.