Growing evidence suggests that anthropogenic noise has deleterious effects on the behavior and physiology of free-living animals. These effects may be particularly pronounced early in life, when developmental trajectories are sensitive to stressors, yet studies investigating developmental effects of noise exposure in free-living populations remain scarce. To elucidate the effects of noise exposure during development, we examined whether noise exposure is associated with shorter telomeres, duller carotenoid-based coloration and reduced body mass in nestlings of a common urban bird, the great tit (Parus major). We also assessed how the noise environment is related to reproductive success. We obtained long-term measurements of the noise environment, over a ~24-h period, and characterized both the amplitude (measured by LAeq, LA90, LA10, LAmax) and variance in noise levels, since more stochastic, as well as louder, noise regimes might be more likely to induce stress. In our urban population, noise levels varied substantially, with louder, but less variable, noise characteristic of areas adjacent to a highway. Noise levels were also highly repeatable, suggesting that individuals experience consistent differences in noise exposure. The amplitude of noise near nest boxes was associated with shorter telomeres among smaller, but not larger, brood members. In addition, carotenoid chroma and hue were positively associated with variance in average and maximum noise levels, and average reflectance was negatively associated with variance in background noise. Independent of noise, hue was positively related to telomere length. Nestling mass and reproductive success were unaffected by noise exposure. Results indicate that multiple dimensions of the noise environment, or factors associated with the noise environment, could affect the phenotype of developing organisms, that noise exposure, or correlated variables, might have the strongest effects on sensitive groups of individuals, and that carotenoid hue could serve as a signal of early-life telomere length.

We studied the effects of the anthropogenic noise environment on the telomere length, body mass, and carotenoid-based coloration of great tit (Parus major) nestlings.  Nest boxes used in the study were located across a noise pollution gradient in Antwerp, Belgium.  The noise environment (LAeq, LA90, LA10, LAmax) was assessed using ~24 hr measurements using environmental noise monitoring kits.  We used a principal components analysis to extract the major axes of variation in the noise environment, and to assess the effect of both the mean and the variance of noise-level variables on the biotic response variables of interest.  

We measured the body mass (±0.1 g) of nestlings on day 15 and also took a small blood sample to assess telomere length at this time.  In addition, we gently extracted ~10-15 yellow contour feathers to measure carontenoid-based coloration. 

Abbreviations used in this dataset are: Cp-crossing threshold in the qPCR reaction used to measure relative telomere length; Et-efficiency of the telomere reaction, Er-efficiency of the GAPDH reaction, RTL-relative telomere length.