Cortisol and conservation: understanding barriers to the recovery of a critically endangered species using stress physiology

Abstract

Chronic exposure to high levels of glucocorticoid hormones can be detrimental to survival and reproduction. Captive breeding and release may inadvertently subject animals to conditions that elicit an increase in glucocorticoids, if conditions in captivity or habitats in the wild are inadequate. The critically endangered Vancouver Island marmot (Marmota vancouverensis) was used to investigate variability in hair cortisol concentration, a measure of systemic glucocorticoid exposure. Marmots were sampled from the captive, captive-release and wild populations. Captive animals had significantly lower cortisol levels than wild animals. Several marmots were also sampled from the historic wild population that lived on Vancouver Island prior to the proliferation of anthropogenic disturbances. A comparison between contemporary and historic animals showed that marmots at most colonies had cortisol levels that were the same as historic level. Three colonies had significantly elevated cortisol levels. Cortisol concentration in the wild was best explained by proximity of a colony to logging roads.