Koala (Phascolarctos cinereus) is an iconic folivorous marsupial native to the sclerophyll forests and woodlands of Australia. Due to the ever-changing habitat, this species is highly vulnerable to anthropogenic factors such as habitat loss and fragmentation, and this is reflected in the increasing number of injured and/or diseased koalas over the years. The majority of adult koalas admitted at wildlife hospitals are deceased, either due to natural causes, or have to be euthanized. Thus, orphaned koala joeys constitute a substantial number of wildlife rescues, and mortality is also prevalent in koala joeys being hand-reared/rehabilitated, with little knowledge about the causes of such high rates of mortality. Wildlife hospitals/rehabilitation centres are inherently stressful, and although the hypothalamic–pituitary–adrenal (HPA) axis plays a vital role in mediating the stress endocrine function (by producing glucocorticoids such as cortisol), there are no studies quantifying glucocorticoids in koala joeys. To contribute to this dearth of research, we sampled a total of seven individuals residing at Port Macquarie Koala Hospital and noted their clinical information. Faecal samples were collected from all seven koala joeys during routine cage cleaning. In total, 123 faecal samples were collected, processed and analysed for cortisol using enzyme-immunoassay (EIA). We used the iterative baseline approach to determine baseline and peak concentrations of FCM in koala joeys. Baseline concentrations ranged between 14.11 ng/g – 51.10 ng/g (healthy – sick), whereas, peak FCM concentrations ranged between 25.65 ng/g – 56.58 ng/g (healthy – sick). There was a significant difference (p < 0.05) between FCM concentrations of healthy and impaired individuals. Healthy individuals displayed relatively consistent FCM concentrations, whereas, diseased individuals displayed a significant increase in FCM concentrations over time. Our study provides the first record of baseline and peak FCM concentrations in rescued koala joeys with their associated clinical condition. Future studies can use the iterative baseline approach to determine FCM concentration in wild koala joeys that can serve as a baseline to compare glucocorticoid levels of rescued joeys.

Direct and indirect anthropogenic factors play a massive role in driving wildlife species towards extinction. Longitudinal retrospective studies identify key ‘factors’ responsible for the decline in numbers of wildlife, however, lack the reasoning behind the events leading to mortality. The overarching aim of this study was to categorize these ‘factors’ into different stressor categories faced by reptiles to understand its impact on an individual, and to compare how each stressor category influences the survival of an individual. The results from this study indicated that almost half of the number of reptiles being hospitalized were due to exposure to preliminary stressors such as lawn mowing incidents and pet attack. Primary and secondary admissions were fairly equal in number, however the mortality rate for secondary admissions was drastically high (~80%). The discussion integrates species’ ecology and stress physiology which can prove to have multi-faceted benefits across the fields of ecology and animal welfare. Ecologists can use the results from this study to comprehend species’ activity patterns to better plan reptilian conservation programs, whereas, for wildlife clinicians and rehabilitators, assignment of stressor categories could be a beneficial tool for bolstering the welfare monitoring program for small native reptiles in clinical settings.