Difficulties of assessing the impacts of the 2019–2020 bushfires on koalas

• Published in: Austral ecology Vol. 48; no. 1; pp. 12 - 18
• Main Authors: Cristescu, Romane H, Gardiner, Riana, Terraube, Julien, McDonald, Kye, Powell, Dan, Levengood, Alexis L., Frère, Céline H
• Format: Journal Article
• Language: English
• Published: Richmond Blackwell Publishing Ltd 01.02.2023
• Subjects: conservation dog; Conservation status; detector dog; DNA fingerprinting; drone; feces; Fires; Forest & brush fires; Genetic fingerprinting; Geography; Habitats; Image acquisition; Impact damage; mortality; non‐invasive methods; Phascolarctos cinereus; Population density; Queensland; sniffer dog; Sniffer dogs; thermal imagery; thermography; vegetation; Wildfires; Wildlife; Wildlife habitats; Wildlife management; Queensland Australia; Australia; New South Wales Australia; Queensland
• DOI: 10.1111/aec.13120
• ISSN: 1442-9985

The 2019–2020 Australian bushfires were unprecedented both in extent and severity, impacting wildlife through direct mortality as well as habitat damage. More than 10% of koala habitat is estimated to have been affected by fires. Estimating the number of koalas lost is crucial to assess koala conservation status and to determine the appropriate management actions required. However, this is not a trivial task, as accurate data on koala distribution and population density before the fires is patchy. Acknowledging this weakness, we sought to estimate fire impact on koalas at specific sites, by comparing habitat areas affected by the fire with habitat areas that were unaffected by the fire, pairing closely related study sites (based on geography and vegetation). To compare koala density, we deployed two koala detection methods; drone‐acquired thermal imagery and detection dogs coupled with genetic fingerprinting, in four fire‐affected sites paired with four control sites in New South Wales and Queensland. Through drone surveys, we detected 140 koalas in 5,240 ha in New South Wales. The detection dogs found 144 scat samples corresponding to 79 unique koalas in 77 ha of transects in Queensland. Our preliminary results show many koalas were still present in fire‐affected areas after the 2019–2020 bushfire season. Koala density was 24 to 71% lower in fire‐affected sites compared with control sites in three of the habitat pairs, whereas unexpectedly, in the fourth pair, we observed a 317% higher koala density in the fire‐affected site. This underlined that koalas can be present in fire‐affected areas and that monitoring their health could be critical for months after the fires. We deployed two koala detection methods to compare koala density; drone‐acquired thermal imagery and detection dogs coupled with genetic fingerprinting, in four fire‐affected and four control sites in New South Wales and Queensland. Our preliminary results show many koalas were still present in fire‐affected areas following the 2019‐2020 bushfire season. Koala density was 24 to 71% lower in fire‐affected sites compared to control sites in three out of four of the habitat pairs.