Swamp Sparrow (IMAGE) Duke University Caption Upon hearing the song of another male in his territory, a male swamp sparrow vigorously waves one wing at a time as a warning signal to ward off a potential intruder. Credit Photo by Robert Lachlan. Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.