DOI: 10.5061/dryad.d51c59zz9
title: Anthropogenic noise is associated with telomere length and carotenoid-based coloration in free-living nestling songbirds

description: 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.
description: 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. 
description: 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.