Controversial idea could aid recovery of bushfire-affected koala populations

“Many koalas were rescued and taken into care in the aftermath of the 2019 and 2020 bushfires but their fate remains uncertain,” said Dr Janette Norman, a molecular biologist and Senior Research Fellow at Southern Cross University.

“Restrictive translocation policies mean that some healthy koalas won’t be returned to the wild because their immediate habitat has been lost.”

With koala numbers decimated it is important that as many koalas as possible are released back into the wild in bushfire-affected areas, Dr Norman emphasised.

“Even a small increase in the number of breeding koalas can improve the rate of population recovery and limit the loss of genetic diversity.”

The proposal, contained in a paper published this month in the Wildlife Research journal by Dr Norman and Professor Les Christidis, also from Southern Cross University, suggests that NSW government policies governing the release of rescued and rehabilitated koala may hinder the recovery of bushfire-affected populations.

”In most cases release back into the wild can only take place within one kilometre of the animal’s original location. With the extent of habitat loss in many areas it will be difficult to meet this requirement,” Dr Norman said.

The authors propose using a spatial genetic framework to inform the selection of release sites for rescued and rehabilitated koalas.

“Using DNA-based approaches we can easily determine how koala populations are structured and prioritise release sites accordingly,” said Dr Norman.

“Depending on the extent of habitat loss, koalas can be released back into their existing home range or translocated to another area within the population. In some cases, it may be beneficial, or necessary, to translocate koalas into another population.”

The idea is controversial, Dr Norman acknowledged, as translocated koalas can experience high rates of mortality.

“We believe these risks can be minimised when koalas are translocated into areas that they would disperse to naturally – the spatial framework enables those areas to be identified.”

The need for a more flexible approach is supported by recent research that showed koalas disperse further than previously thought.

In a 2019 study, Dr Norman and colleagues found that koalas in the Lismore area, in the NSW Northern Rivers region, dispersed on average 5.6 kilometres with long distance movements up to 16.8 kilometres being relatively common. Koalas are known to disperse even further when their habitat is disturbed, such as during a bushfire.

“Release sites for translocated koalas should be based on these natural patterns of dispersal rather than being constrained by inappropriate translocation limits such as the 1 km rule,” Dr Norman said.

“Dispersal patterns vary amongst populations so it makes sense that translocation limits should also vary.

“Translations not only have the potential to support the recovery of bushfire-affected populations but could be used to bolster the health of koala populations in areas where their habitat has become fragmented and natural dispersal patterns disrupted.”

About the study

Title: A spatial genetic framework for koala translocations: where to now?

Scientific journal: Wildlife Research

Digital publication: doi.org/10.1071/WR20055

Media contact: Sharlene King, media office at Southern Cross University, 0429 661 349 or scumedia@scu.edu.au