Singing Swamp Sparrow (IMAGE) Duke University Caption The dawn chorus of birdsong may be a warm-up routine that helps birds meet the physical demands of singing and deliver their best performance later in the day. Credit Photo by Robert Lachlan, Royal Holloway, University of London Usage Restrictions Please credit Robert Lachlan, Royal Holloway, University of London 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.