Chronic anthropogenic noise disrupts glucocorticoid signaling and has multiple effects on fitness in an avian community

Abstract

Anthropogenic noise is a pervasive pollutant that decreases environmental quality by disrupting a suite of behaviors vital to perception and communication. However, even within populations of noise-sensitive species, individuals still select breeding sites located within areas exposed to high noise levels, with largely unknown physiological and fitness consequences. We use a study system in the natural gas fields of northern New Mexico to test the prediction that exposure to noise causes glucocorticoid-signaling dysfunction and decreases fitness in a community of secondary cavity-nesting birds. In accordance with these predictions, and across all species, we find strong support for noise exposure decreasing baseline corticosterone in adults and nestlings and, conversely, increasing acute stressor-induced corticosterone in nestlings. We also document fitness consequences with increased noise in the form of reduced hatching success in the western bluebird (Sialia mexicana), the species most likely to nest in noisiest environments. Nestlings of all three species exhibited accelerated growth of both feathers and body size at intermediate noise amplitudes compared with lower or higher amplitudes. Our results are consistent with recent experimental laboratory studies and show that noise functions as a chronic, inescapable stressor. Anthropogenic noise likely impairs environmental risk perception by species relying on acoustic cues and ultimately leads to impacts on fitness. Our work, when taken together with recent efforts to document noise across the landscape, implies potential widespread, noise-induced chronic stress coupled with reduced fitness for many species reliant on acoustic cues.

Keywords: acoustic environment; anthropogenic noise; birds; perceived predation risk; stress response.

Fig. 1.

This conceptual figure shows the study system design and the acoustic properties of sites with and without compressor noise. (Left) The three nested spatial scales included in the study: the full system (Top), loud and quiet pairs (Middle), and individual sites (Bottom). The Bottom shows nest boxes (labeled 1–10) arrayed around the site center, which was the centroid location of a well pad. (Center) A spectrogram of recorded background noise at a louder area (Upper) and quieter area (Lower). The songs of four common species that are found in RCHMA, including representatives from this study are included to depict the masking potential of noise: (a) spotted towhee; (b) plumbeous vireo; (c) ash-throated flycatcher; and (d) western bluebird). (Right) Power spectra that show the amplitude or “power” of compressor noise at frequencies between 0 and 12 kHz.

Fig. 2.

The graph shows the relationship between cort and noise in all three species and two life stages. Baseline cort levels for both adults and nestlings were negatively affected by noise (Left and Center Columns, respectively), while acute stress-induced cort levels in nestlings were positively affected by noise (Right Column). For each model, the effect of noise was consistent across species, irrespective of species-specific cort levels. The gray-shaded areas indicate the 85% CIs for each estimated effect.

Fig. 3.

Hatching success in the western bluebird was negatively affected by noise. The gray-shaded area indicates the 85% CI.

Fig. 4.

The relationship between noise exposure and nestling development, represented by principal components axes, in all three species. Noise exposure had a nonlinear effect on feather development (Upper Row) and body size (Lower Row) in nestlings that was supported across species. The gray-shaded areas indicate the 85% confidence intervals for each estimated effect.

Fig. 5.

Adult female baseline cort, measured during incubation, was positively associated with hatching success. The gray-shaded areas indicate the 85% confidence intervals for each estimated effect.