Birds Driven Away by Road Noise, Study Confirms

The results of an experiment in Idaho suggest that road noise plays a significant negative role in the lives of birds in the wild.

Based on previous studies, researchers from Boise State University already knew road noise played a negative role on wildlife populations, but they said the results of prior studies were contaminated by other factors on the roadside including visual disturbances, collisions and chemical pollution.

To create a scenario where these confounding elements would not be a play, the researchers constructed a phantom road on a ridge near the Idaho Bird Observatory's field site on Lucky Peak, the southernmost peak on the Boise Ridge.

The researchers put speakers in trees and played roadway noises in four-days-on, four-days-off intervals during the regular autumn migratory period for area birds.

The results led to confirmation of what the previous studies put forth: roadway noises drive birds away.

"We documented more than a one-quarter decline in bird abundance and almost complete avoidance by some species between noise-on and noise-off periods along the phantom road," said Jesse Barber, assistant professor of biological sciences at Boise State. "There were no such effects at control sites. This suggests that traffic noise is a major driver of the effects of roads on populations of animals."

Christopher McClure, a post-doctoral research associate at Boise State's Department of Biological Sciences, said the study is "the first study to experimentally apply traffic noise to a roadless area at a landscape scale, thus avoiding the other confounding aspects of roads present in past studies."

The research is published in Proceedings of the Royal Society B: Biological Sciences.