Background
Koalas (Phascolarctos cinereus) can be found on the east-coast of Queensland, New South Wales, the Australian Capital Territory, Victoria, and South-Australia (Woinarski & Burbidge, 2020). Despite being an important contributor to both the ecosystem and the tourism industry, koala populations are declining across most of their range within Australia (Woinarski & Burbidge, 2020). After previously being listed as ‘vulnerable to extinction’, in February of 2022, the Australian Government officially listed koalas as ‘endangered’ in Queensland, New South Wales, and the Australian Capital Territory (Australian Government, 2022). This change was made due to koala population decline resulting from key threats such as climate change, habitat loss, dog predation, vehicle strike, and disease (Australian Government, 2022). Despite the fact that multiple threats often present in a given habitat regardless of the location, it is the scale of these threats relative to the population that can adversely impact the persistence of koalas (Youngentob et al., 2021). Of course, endocrinology allows vertebrates to display plasticity in response to environmental threats (Denver, 2009; Wingfield, 2013). However, it has been well documented that over-activation of the physiological mediators involved in responding to threats can create undue stress, causing deleterious effects on health which often leads to a greater susceptibility to disease (Sapolsky et al., 2000). Individually, conservation physiology and social science are disciplines frequently employed in the conservation of wildlife. However, this thesis will utilise both to enhance animal welfare and drive positive conservation outcomes of wild koalas in South-East Queensland.
Aims
- Outline the primary threats for wild koalas within South-East Queensland who are reported to veterinary clinics, and how these threats affect the likelihood of each koala either being released, euthanised, or dying.
- Measure the homeostatic health parameters for South-East Queensland koalas using faecal glucocorticoid metabolite concentrations.
- Measure the agreement of two cortisol enzyme-immunoassays used to determine koala faecal glucocorticoid metabolites.
- Assess the behavioural intention of people living in South-East Queensland to promote positive koala conservation.
Methodology
To meet the first aim, I analyzed 50,858 reports that had been made to the South-East Queensland Wildlife Hospital Network between 1997 and 2019. A test was performed to determine the effect of age, sex, and aetiology on the outcome of a koala.
To meet the second aim, I used faecal glucocorticoid metabolite concentrations from wild, captive, healthy and sick koalas to replicate the “Reactive Scope Model”, a model proposed to measure the physiological mediators associated with the stress response.
To meet the third aim, I measured the agreement between two cortisol enzyme-immunoassays, one of which is biologically validated for koala faeces, but is extremely time consuming, uses antibodies that are difficult to procure locally, and cannot be performed in house, whereas the other is quick to perform, uses antibodies that are easy to procure locally, and can be performed in house, but it is not yet biologically validated.
To meet the fourth aim, I conducted a survey based on the “Theory of Planned Behaviour” to measure the behavioural intention of people living in South-East Queensland to promote positive koala conservation.
Outcomes
By tracking trends over time, we can assess whether conservation measures are effective in reducing hospital admissions of koalas. Long-term data can also help detect shifts in koala populations and their health.
Developing a model that can assist with measuring the physiological mediators associated with the stress response can provide those managing wild koala populations with an insight into the health issues related to chronic stress by avoiding the invasive task of capture and release.
Building a case for validating a commercially available cortisol enzyme-immunoassay will make it easier for those managing wild koala populations for habitat restoration or translocation programs to detect disease early, which is critical for wild koala health management and preventing disease outbreaks.
Finally, social science research can provide evidence and recommendations to influence conservation policies and regulations related to koalas and their habitats. This may involve advocating for stronger protections or incentives for habitat conservation and ensures that conservation efforts are not only ecologically sound but also considerate of the social and cultural contexts in which they occur.
References
Australian Government. (2022). EPBC Act List of Threatened Fauna. https://www.environment.gov.au/cgi-bin/sprat/public/publicthreatenedlist.pl
Denver, R. J. (2009). Structural and functional evolution of vertebrate neuroendocrine stress systems. Annals of the New York Academy of Sciences, 1163(1), 1-16. https://doi.org/10.1111/j.1749-6632.2009.04433.x
Sapolsky, R. M., Romero, L. M., & Munck, A. U. (2000). How do glucocorticoids influence stress responses? Integrating permissive, suppressive, stimulatory and prepartive actions. Endocrine Reviews, 21(1), 55-89.
Wingfield, J. C. (2013). The comparative biology of environmental stress: Behavioural endocrinology and variation in ability to cope with novel, changing environments. Animal Behaviour, 85(5), 1127-1133. https://doi.org/10.1016/j.anbehav.2013.02.018
Woinarski, J., & Burbidge, A. A. (2020). Phascolarctos cinereus (amended version of 2016 assessment) (IUCN Red List of Threatened Species). https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjy6svstfb-AhVymFYBHen_ANsQFnoECAwQAQ&url=https%3A%2F%2Fwww.iucnredlist.org%2Fspecies%2Fpdf%2F166496779&usg=AOvVaw0mddzuDs3e3FTZlBQ7PFv8
Youngentob, K. N., Marsh, K. F., & Skewes, J. (2021). A review of koala habitat assessment criteria and methods (A report prepared for the Department of Agriculture, Water and the Environment, Canberra). https://www.agriculture.gov.au/sites/default/files/documents/review-koala-habitat-assessment-criteria-and-methods-2021.pdf