A major study earlier this year that examined 492 protected areas in the USA found that 62 percent of the parks, wilderness areas and green spaces were twice as loud as they should be. About 21 percent were 10 times as loud. Chronic exposure to traffic, generators and airplanes can lead to negative consequences for wildlife. Researchers like Nathan Kliest are just getting a handle on exactly how all that noise impacts animals. Kliest, formerly of the University of Colorado Boulder and now at SUNY Brockport, recently investigated the impact of chronic noise on birds in the Southwest.
The results, reported in The Proceedings of the National Academy of Sciences, showed that mountain bluebirds avoided the noisy areas, and flycatchers also kept their distance, though they were a little more tolerant. Western bluebirds, however, seemed fine with increased noise levels and nested everywhere on the sites. But that doesn’t mean they were unaffected. Nestlings in high-noise areas had smaller body sizes and reduced feather growth.
The team also found something unexpected: All the birds nesting in noisy areas had lower baseline levels of corticosterone, a key stress hormone. “I was really surprised,” said Kleist, who thought the birds’ stress hormones would be through the roof. “I saw these decreasing baseline stress hormones while seeing decreasing reproductive and hatching success in western bluebirds. It was a juxtaposition of results I didn’t expect.”
There is still a lot to work out about how exactly noise impacts wildlife and human health, but Kleist said there’s mounting evidence that it’s an element policymakers and land managers need to begin thinking about. “Noise might not be good for wildlife or humans. It reduces the value of habitats like parks,” he said. “To make them as valuable and useful as possible to wildlife, we need to consider the impact of noise.”
This is an edited extract from an article published in Ecowatch.