Evaluation of physiological stress in the Koala (Phascolarctos cinereus) ensued from extreme environmental change

Koalas (Phascolarctos cinereus) are the only extant representatives of Australia’s unique marsupial family Phascolarctidae and were listed as nationally Vulnerable in 2012. Causes of mortality are diverse, although the disease chlamydiosis, dog attacks, collisions with cars, and loss of habitat represent the principal reasons for the continued species decline. Sick and/or injured wild Koalas that are rescued and enter into wildlife hospitals can provide useful information on the sub-lethal impacts of environmental stressors on wildlife.In this research, we evaluated physiological stress in wild koalas during treatment and recuperation in a veterinary clinic setting. A recently validated non-invasive faecal glucocorticoid metabolite (FGM) enzyme immunoassay(EIA) was employed to quantify nominal baseline levels of stress hormones in the koala.The intensity of stressors was identified using routine health checks. Stressors were categories as acute environmental trauma (dog-attacks and collision with cars) and prolonged disease (chlamydia) and climatic variability (summer heat waves/forest fires). We provide results to show the variation in FGMs in these rescued wild koalas and their association with the stressor categories. We also show the changes in FGMs in Koalas during treatment and recuperation period. Our non-invasive FGM EIA provides a sensitive assay system to detect the physiological response of wildlife to extreme environmental changes. We recommend the integration of conservation physiology tools into wildlife management programs that will provide vital information on the animal response to environmental change and management interventions from a unique physiological perspective.