Population consequences of physiological responses to stressors: A road map for endocrine data

Environmental change causes physiological effects that can last years in long-lived species, yet there is a dearth of methods for quantifying such effects and their population consequences across the necessary decadal timescales. The Population Consequences of Multiple Stressors (PCoMS) framework is intended to link short-term responses to stressors to health, then to vital rates and from there to population-level effects. To date, implementations of the PCoMS framework have primarily focused on behavioral responses of marine mammals to stressors, enabled by data available from biologging devices. However, technological advances have facilitated the collection of physiological data, particularly hormones, through techniques such as extraction and quantification of hormones in respiratory vapor (blow), feces, vibrissae, blubber, skin, and baleen, amongst others. Using baleen specimens from bowhead whales (Balaena mysticetus) that were sampled for stable isotopes and adrenal, thyroid, and reproductive hormones, we demonstrate how these individual histories can be used within the PCoMS framework to begin modelling the linkages between ecological change, anthropogenic actions, individual physiology, and potential population impacts.