A 29-year retrospective analysis of koala rescues in New South Wales, Australia

Abstract

The koala (Phascolactos cinereus) is currently listed by both the IUCN and the Australian Governments Threatened Species Scientific Committee as vulnerable to extinction with a decreasing population trend. This listing can be attributed to climate change and its impact on ecosystems, and anthropomorphic environmental change due to extensive land clearing and habitat fragmentation. These have both been proven to induce stress, which influences the onset of disease. This novel study performed a retrospective analysis whereby records for 12,543 wild, rescued koalas in New South Wales (NSW), Australia were studied in order to determine trends in koala sightings, clinical admissions and injury diagnoses over a period of 29 years (1989-2018). Results indicated that between all three study locations (Port Stephens, Port Macquarie and Lismore), the most common reason koalas were admitted into care was because of disease, the most common disease diagnosed was signs of chlamydia, and the most common outcome for koalas admitted into care was released. At Port Stephens, mature and female koalas were diagnosed with a disease more than any other age or sex, while juvenile and male koalas were released (back into the wild) more than any other age or sex. Additionally, there were fewer koalas with a disease and fewer koalas released in Port Stephens as each year progressed. At Port Macquarie, mature and male koalas were diagnosed with a disease more than any other age or sex, while juvenile and female koalas were released more than any other age or sex. Additionally, there were more koalas with a disease and fewer koalas released in Port Macquarie as each year progressed. At Lismore, adult and female koalas were diagnosed with a disease more than any other age or sex, while joey and male koalas were released more than any other age or sex. Additionally, there were more koalas with a disease and fewer koalas released in Lismore as each year progressed. Determining trends in clinical admissions and diagnosis over such a substantial period of time is an important factor in preventing the continuing decline of koalas throughout Australia, and in particular NSW. It is important to note that there are cultural differences between koala rescue groups in the three study locations (Port Stephens, Port Macquarie and Lismore). These differences may be reflected in the outcomes of koala patients as each group are driven by their own management team. It is essential that any further decline of koala populations is prevented, however this can only be achieved through informed recommendations through research studies such as these. These recommendations should lead to government legislation which can provide stronger protection to koala habitat.