Koala response to post-fire recovery of forest habitat

Context The koala (Phascolarctos cinereus) is now listed as Endangered for most of its range, mainly due to habitat loss; however, wildfire is an increasing factor. Extensive wildfires in South-east Queensland in 2019 allowed us to monitor habitat recovery on a 230-ha property, and assess habitat preferences of koalas in this location and in the surrounding region of 12,000 km2. Aims The study aimed to determine if areas with koala presence records tend to burn more than others; if koalas are selective for forest type, terrain, tree species and tree size; and if their habitat recovers after fire and koala recolonisation occurs. Methods We used the Spot Assessment Technique on the property to survey for koala scat presence and tree species use. We measured GeoCBI on the property, and extrapolated this regionally using Differenced Normalised Burn Ratio from Sentinel-2 data to estimate fire severity. We used Atlas of Living Australia koala records as regional sample points for forest type, burn estimates, elevation, slope and aspect. Key results The proportion of regional koala occurrence records in burnt areas was not significantly different to random. Koalas mostly utilised three particular tree species in our local study area and one of four forest types. Koala presence decreased after the first year of fire recovery, then increased slightly in the fourth year. Koalas consistently utilised larger trees. Regionally, koalas notably preferred two forest types out of 85 used. Most koalas occurred on flatter, lower elevations. Southern and eastern aspects were preferred. Conclusions Koalas are selective for forest type, terrain, tree species and tree size. Implications Contrary to some other studies, which found that koala population recovery after fire took months, our study suggests that population recovery after fire could take years, and death or removal of large trees following severe fires will lead to reduced koala habitat.