Meeting Abstract
Since first publication in 2008, feather corticosterone (CORT) has become a widely used metric of stress physiology in birds. Feather CORT has been correlated with various facets of avian biology including breeding success, coloration, and nutritional status. However, we still know very little about how measures of metabolites in feathers relate to circulating CORT levels. Two studies have evaluated the relationship between plasma CORT and feather CORT metabolites, but have only noted a relationship when animals with CORT implants are included in the analysis. This is not especially surprising, as plasma CORT levels represent one brief moment in time, while the feather is grown over a period of days to weeks. The variation in CORT experienced by the animal over this extended time frame is unlikely to be represented in the one time-point measured in the plasma. We used a more integrated measure of CORT secretion – fecal glucocorticoid metabolites (FGM) – to look for relationships between feather CORT and general glucocorticoid status in individuals. To this end, we brought house sparrows into captivity, pulled two tail feathers, and collected fecal samples over the next 3-4 weeks of feather growth. We are currently measuring the fecal glucocorticoid metabolites in the samples, and will compare individual variation in FGM to individual variation in feather CORT metabolites.
