Traffic noise affects embryo mortality and nestling growth rates in captive zebra finches.

Over the past two decades, studies of songbird populations have detected decreases in the reproductive success of individuals living in urban areas. Anthropogenic noise is considered to be particularly detrimental, however the exact relationship between noise and reproductive success is still unclear because noise is often correlated with many other detrimental factors (e.g., predation, reduced territory quality). We used an experiment to specifically test the effects of urban noise on reproduction of captive zebra finches (Taeniopygia guttata). We found that latency to breed and the size of successfully fledged clutches were consistent between groups, however success of initial nesting attempts was reduced by traffic noise. Further, this reduced success leading to increased numbers of nesting attempts by birds in the noise condition was due to higher levels of embryo mortality in the traffic noise treatment group, which also suffered a lag in nestling growth rates during the first two weeks post-hatch. While parental baseline circulating corticosterone was not chronically affected by noise treatment, we identified some interaction effects whereby certain reproductive measures (laying latency and clutch size) were most strongly affected by treatment when mothers had higher levels of baseline corticosterone. These results indicate that traffic noise may reduce reproductive success through changes in parental behaviour, and that traffic noise may disproportionately affect chronically stressed individuals during reproduction. J. Exp. Zool. 323A: 722-730, 2015.