Author	Lane MR, Lowe A, Vukcevic J, Clark RG, Madani G, Higgins DP, Silver L, Belov K, Hogg CJ, Marsh KJ 24
Year	2023
Population	56 koalas in the Snowy Monaro Shire of NSW impacted by the 2019–20 bushfires, 31 of which were rescued, rehabilitated and released, 9 of which were non‐rescued and living in the burnt environment and 16 of which were non‐rescued and living in the non‐burnt environment.
Intervention studied	Health of rescued and released koalas after bushfire compared with non‐rescued koalas in burnt and unburnt habitat.
Outcome studied	Health data and long‐term health risks for rehabilitated koalas who have been released into burnt habitats.
Design and sample size	After the 2019–20 bushfires, 31 koalas in the Snowy Monaro region of NSW were rescued and rehabilitated between January and March 2020. Initial health data was collected from all individuals however 12 of them were fitted with trackers when released and their health data was compared with non‐rescued koalas also fitted with trackers in the same area at pre‐release (May–December 2020) and recapture (February–May 2021). Due to the mosaic of fire burn, the non‐rescued group was divided into nine individuals from burnt habitat and 16 individuals from unburnt habitat.
	Three health checks were conducted ‐ the initial health check on the 31 rescued koalas, the pre‐release health check on the 12 rehabilitated koalas fitted with trackers and the non‐rescue groups, and the recapture health check on individuals still fitted with trackers ‐ by this stage, the rehabilitated group contained four individuals and the non‐rescue groups contained eight individuals from burnt habitat and six from unburnt habitat.
	Health checks were conducted under sedation and koalas were checked for age (from tooth wear), sex, presence of burns, young in pouch, physical condition, abdominal fill and aural health. In addition, blood collection was performed for haematology, biochemistry and genetic analysis, and ocular swabs, genital swabs and ear tissue biopsy were taken, and Chlamydia status was determined.
Main findings	There was a statistically significant difference in body condition score (BCS) in the rehabilitated koala group between rescue, pre‐release and recapture health checks. The BCS at the initial check was very low (1.3 out of 5), but by recapture, there was no significant difference between BCS of koalas in the rehabilitated and the nonrescue groups. This indicates that within four months of fire, there is sufficient quantity and quality of food to support healthy koalas.
	Three of the rehabilitated koalas had burn injuries at rescue, one of which required regular bandaging, and all made a full recovery.
	Ocular chlamydiosis was detected in three individuals in the rehabilitation group and none in the non‐rescue groups. Urogenital chlamydiosis was detected in 58% of the rehabilitated group, 44% of the non‐rescue from burnt habitat group and 63% of the non‐rescue from non‐burnt habitat group. It was found that rates of chlamydial shedding did not differ between groups indicating rehabilitation or fire did not have a major impact on Chlamydia status.
	Blood biochemistry parameters were mostly within reference intervals while the following differences are relevant to koala rehabilitation: Urea concentrations were higher for rehabilitated and non‐rescue koala groups in the burnt habitat compared with non‐rescue koalas in the unburnt habitat, but by the recapture health check urea was not significantly different between groups, and this could indicate improvement in nutritional status. The liver enzyme AST was elevated at the initial health check in rehabilitated koalas and this could indicate stress.
	Haematology results were also within the reference range for most individuals with no significant differences found between koala groups or health checks for PCV, TPP, haemoglobin, MCHC, platelet count, leukocytes, monocytes, eosinophils or basophils, and while differences were found between lymphocyte and neutrophil values, they were within reference range. There was no significant difference found between haematology parameters and Chlamydia status or survival rates.
Limitations	Of the 56 koalas in the original survey, only a small subset ultimately received health checks, with the final health check involving only four individuals from the rescued group and eight individuals from the nonrescued groups. Given the small sample size, individual variation and that some differences noted were within reference ranges, it is questionable whether conclusions can be made about haematology and biochemistry parameters.