Nobody likes traffic—including birds. Even moderate road noise drives many  from their habitat, and new evidence suggests bad health effects for those that stick around.

Weight loss, for example. Birds exposed to traffic sounds lost body mass during fall migration, a period when they need to gain fat to fuel their long flights, according to a study from Idaho’s Boise State University.

"Birds are at their physiological limits" when migrating, says study co-author Heidi Ware, education and outreach director of the university's Intermountain Bird Observatory, and the noise distracts them from feeding. Beyond weakening the birds for their long trip south, Ware says, the lower weight can hurt breeding chances in the spring.

The research, published Monday in the Proceedings of the