Traffic Noise Exposure in Eggs and Nesting Birds Leads to Lifelong Fitness Reduction

A new study has revealed that eggs and nesting baby birds exposed to moderate levels of human-made traffic noise experience significant, direct, and cumulative negative effects on their long-term development and fitness. The findings emphasize the disruptive impact of noise on physiology, development, and reproduction, resulting in lifelong fitness reduction. The study calls for a re-evaluation of the threat posed by human-made noise and the need for noise reduction measures.

The Growing Concern of Noise Pollution

Noise pollution has become a global problem, even in the most remote places on Earth. While the negative impacts of exposure to human-made noise pollution on animals have been well documented, including effects on acoustic communication and behavior, recent studies have begun to show adverse effects on physiology, reproduction, and development across various animal species, as well as in humans. However, little is known about how noise impairs development and fitness, and whether noise sound waves are inherently harmful for developing young or simply disturbs and/or alters parental behaviors.

Studying the Impact of Noise on Zebra Finch Development

To better understand these impacts, Alizée Meillère and colleagues investigated the fitness impact of developing wild zebra finch birds in a moderately noisy environment. They exposed soon-to-be-hatching eggs and postnatal nesting birds to specific acoustic environments, including recordings of traffic noise (at levels that birds routinely encounter in an urban environment), zebra finch songs, or silence.

The study found that noise doesn’t just alter adult behavior but had direct impacts on bird growth and fitness when only eggs are exposed to noise. Birds exposed to moderate human-made traffic noise in the egg experienced long-term impacts, including impaired nesting growth, shorter telomere length, and reduced fitness as adults.

“The study of Meillère et al. on zebra finches reinforces the notion of negative noise impact on chicks as they develop in the egg, an effect that extends to pre-natal exposure to noise in other species, including humans,” writes Hans Slabbekoorn in a related Perspective.

The findings suggest that the acoustic environment of breeding birds in cities and along highways should be better managed, and that the acoustic comfort in hospital environments for pregnant mothers and babies warrants special attention. The study underscores the need for a reassessment of the threat posed by human-made noise and the importance of implementing noise mitigation measures to protect wildlife and human health.

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