On International Threatened Species Day, a new report commissioned by the World Wide Fund for Nature-Australia found the 2019-20 bushfires resulted in the loss of about 71% of koala populations in fire affected areas at six locations on the north coast of New South Wales.
Four major blazes – the Wardell fire, the Busby’s Flat fire, the Crestwood-Lake Innes fire, and the Hillville Road fire – swept through the study areas.
The koala occupancy declines at the six fire grounds varied from 34% in an area of the Lake Innes Nature Reserve near Port Macquarie, to a likely 100% loss in the Kiwarrak area south of Taree, where researchers could find no evidence that any koalas survived.
On the up-side, the report, released on the eve of National Threatened Species Day, found koalas were five-times more likely to survive in areas where forest canopies were unburnt or partially burnt compared to fully burnt.
“This is the first scientific study to enter charred forest and quantify the impact of the bushfire crisis on koalas. WWF commissioned this research to provide credible information on our national icon, loved at home and abroad. A 71% decline is massive, nearly three quarters of koalas in these locations were lost.
“That’s why it’s so important that national environment laws are strengthened to protect koalas and all threatened species,” said WWF-Australia CEO Dermot O’Gorman.
Ecological consultancy Biolink surveyed 123 sites at the six fire grounds searching for scats below large koala food trees. Finding unburnt scats confirmed that at least some koalas had lived through the fires.
Biolink chose locations with pre-fire koala occupancy data to enable a comparison to post-fire occupancy.
Dr Stephen Phillips, specialist koala ecologist at Biolink, said the capacity of koala populations to recover will depend on the severity of the fire in their area, the original population size, management actions taken to assist populations to rebuild, and whether there is sufficient recovery time before the next fire event.
“We’ve got to identify where the remaining koala populations are located in each fire affected area, the size of each population, and focus our conservation efforts on those populations which remain viable. We need to wrap them in cotton wool,” Dr Phillips said.
The report outlines actions to assist recovery. Field work by Biolink confirmed the accuracy of the Google Earth Engine Burnt Area Map (GEEBAM) which detects how badly the tree canopy has been burnt.
Where GEEBAM indicates forest canopy is unburnt or only partially affected, logging or other disturbances should cease until detailed assessments are made of the presence of koalas and the extent of their distribution.
Outside of these areas, preferred koala food trees with a diameter at breast height greater than 300mm should be retained to help koalas move across a landscape where fire damage has caused populations to become increasingly isolated.
“Fire breaks can be created around resident koala populations using low-intensity, hazard reduction burns but they must be carefully controlled. Hand-raking to remove fuel from around the bases of the larger koala food trees can reduce canopy scorch and help protect koalas,” Dr Phillips said.
Mr O’Gorman said people in Australia and around the world would be deeply concerned by the report’s findings.
“The Australian bushfires showed the world a future that nobody wants. Many parts of the globe will be experiencing more extreme bushfires due to climate change. Koala numbers may not recover before another blaze sweeps through the east coast causing localised extinctions,” said Mr O’Gorman.
“If populations of pandas or tigers faced a similar fate there would be an international outcry. WWF-Australia is calling for us as a nation to have koala bounce back plan to save east coast populations,” he said.
The report noted that fire was a contributing factor in the decline of koalas in the Tweed and Brunswick Coast, the eastern parts of Port Stephens LGA, and the Pilliga. The Pilliga koalas were once considered the single largest population remaining in NSW. In little more than two decades they declined so rapidly they are now thought to be functionally extinct.
“The plight of the Pilliga koalas is a sobering reality check of the challenges ahead for koala recovery and conservation, and also implies that the threat of localised extinctions is more immediate than we might otherwise have considered,” Dr Phillips said.
Story Source: WWF Australia