A western Bluebird (IMAGE) Proceedings of the National Academy of Sciences Caption This is a western bluebird. Credit Image courtesy of Dave Keeling (Emeritus, California Polytechnic State University, San Luis Obispo, CA). 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.