Western bluebird (IMAGE) University of California - Davis Caption A western bluebird perches on a tree branch. Tree canopy is especially important for birds during heat waves and extreme temperatures. Credit Daniel Karp/UC Davis Usage Restrictions Credit must be given to the creator. Only noncommercial uses of the work are permitted. No derivatives or adaptations of the work are permitted. License CC BY-NC-ND 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.