Land use influences the faecal glucocorticoid metabolites of multiple species across trophic levels

Human landscape modification is amongst the greatest drivers of biodiversity loss. Measuring faecal glucocorticoid metabolites (FGM) in wildlife is of great value to measure the impact of human activities on local biodiversity because FGM offer a non-invasive way of measuring an animal's response to changes in its environment in the form of adrenocortical activity. Here, we measure the concentration of FGM in three native Australian mammal species belonging to different trophic levels: the Tasmanian devil (Sarcophilus harrisii) and the spotted-tailed quoll (Dasyurus maculatus), both carnivores, and an omnivore that is primarily an arboreal folivore, the brushtail possum (Trichosurus vulpecula), and compare the FGM concentrations across three major land uses: agricultural, plantation and National Parks. We find that land use influences the FGM concentration in all three species and that general patterns emerge in FGM concentrations across multiple species and trophic levels in relation to land use. Specifically, plantation landscapes are associated with the lowest median and range of variation of FGM concentration in all species with several plausible explanations depending on the species. Our results suggest that measuring FGM in multiple species can offer a time- and cost-efficient snapshot of how different animals experience the same environment, potentially simplifying FGM interpretation. This study is the first to apply a community approach to understand how multiple species of different trophic levels respond collectively, and separately, to different land use types.