“Manufactured noise coming from everything from natural-gas development to automobiles is increasingly considered a major pollutant. Eighty-three percent of the land area in the continental United States, for instance, now sits within two-thirds of a mile of a road, according to a 2003 study.
To test noise’s effects, Dr. Barber of Boise State and several colleagues built a “phantom road” in a forest outside Boise, Idaho, that is a popular stopover for birds during fall migration. The road consisted of a half-kilometer array of speakers through the woods that broadcast automobile noise and could be switched on and off.
Noise alone, they found, had harmful effects on many of the birds. “What we found was that they had lower overall body condition and they gained significantly less weight when the road was ‘on,’ ” Dr. Barber said. The findings are under review for publication.”