Global warming is increasing extreme and unpredictable weather events globally, yet it is unclear how environmental uncertainty may adversely affect organismal physiology. One way to approach this problem is to determine how organisms that have evolved under naturally unpredictable environments have adapted to these conditions. Three main physiological traits are shown to help vertebrates to cope with environmental stressors, including (i) immune function, (ii) glucocorticoid hormones and (iii) oxidative stress. Differences in physiology among species correlate with global environmental gradients, demonstrating there is a relationship between physiology and habitat conditions. However, life-history differences among species can confound these analyses, thus it remains unclear which physiological traits can help individuals within a species cope with environmental uncertainty. We explore how populations of superb starlings (Lamprotornis superbus) that have naturally evolved in unpredictable habitats cope physiologically with differences in total annual rainfall and uncertainty in rainfall within Kenya. Specifically, we compare physiology among 9 populations of superb starlings that experience drastic differences in rainfall. Preliminary results indicate that glucocorticoids are elevated in birds living in habitats where rainfall is unpredictable (including baseline, stress-induced and ACTH-challenged glucocorticoid levels). These results suggest that elevated glucocorticoids allow superb starlings to live under unpredictable environmental conditions. This research demonstrates how species cope physiologically under diverse and variable environments, enhancing our ability to predict how vertebrates facing environmental unpredictability due to global warming may respond.