Dark-eyed Junco (IMAGE) Michigan State University Caption Danielle Whittaker, BEACON researcher, used dark-eyed juncos to demonstrate how bacteria in a bird's preen gland determines the scent of the bird Credit Nicole M. Gerlach Usage Restrictions With credit 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.