Validation of an assay to measure glucocorticoid metabolites in the droppings of little penguins (Eudyptula minor)

Monitoring adrenal activity can provide insight into an animal’s physiological state and can be assessed non-invasively via excreta (e.g. bird droppings). However, before this technique can be used, it needs to be validated for each species. In this study, we biologically validated an assay for monitoring adrenocortical activity via faecal glucocorticoid metabolites (FGM) in little penguins (Eudyptula minor). The validation incorporated a pre-scheduled husbandry event that is potentially stressful (annual veterinary health check). Four penguins were randomly selected a priori and immediately following their veterinary examination, they were transferred to off-display housing to facilitate individual collection of droppings over the following five days. All penguins exhibited a peak in FGM concentrations within 24 h of the start of the health check and on average FGM concentrations increased six-fold above an individual’s mean baseline value. This validated FGM assay provides a valuable addition to the suite of tools available to monitor little penguins in zoos and in the wild.