The journal Oikos has just blogged about Dr. Christine Madliger’s new  paper entitled “Do baseline glucocorticoids simultaneously represent fitness and environmental quality in a declining aerial insectivore?” Christine’s results are some of the first to combine an examination of environmental variation and fitness to assess whether baseline glucocorticoids are the potent biomarkers they are always assumed to be. Researchers often simply assume that a causal link exists between the two, but Christine’s correlative and experimental work in free-living Tree swallows now calls this simplistic prediction into question. Great to see the world is beginning to look at this trait with a more complex eye. Great work Christine!