Traffic noise is just another inconvenience for many of us. But for wildlife, noise from honking, and zooming vehicles can often be an insidious threat: it can degrade habitats without leaving any physical evidence of change, warns a recent study published in the Proceedings of the National Academy of Sciences.Road noise — even in moderate levels — pushes migrating birds away from their stopover habitats, researchers from Boise State University in Idaho found. Those that stay back become weak.“I was initially surprised that even moderate road noise — comparable to a suburban setting — would have such a wide-ranging impact on migrating birds,” William Laurance, a professor at James Cook University in Cairns, Australia, who was not involved in the study, told Mongabay. “On reflection, however, I guess such migrators have to be hyper-vigilent about noise, as they’re constantly moving to new areas where unseen predators could be lurking.”