Birds (IMAGE) Smithsonian Tropical Research Institute Caption By keeping their bodies warm at all times, birds and mammals may be effectively priming their immune systems to withstand virulent pathogens. Credit Michael Logan 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.