Study Shows Bleak Outlook For Koalas In Mackay / Isaac Without Intervention

Central Queensland’s endangered koala population is facing a dire future if nothing is done to prevent the number of animals being killed by vehicles.

That’s according to CQUniversity and Griffith University koala researchers who have released findings from two separate studies focused on a stretch of the Peak Downs Highway, between Mackay and Nebo in Queensland.

Lead researcher CQUniversity’s Dr Rolf Schlagloth said Koala Research-CQ and its collaborators have analysed koala roadkill data spanning nearly a decade, and the outcomes aren’t good.

Over this 51km section of highway, 145 koalas were struck by vehicles in 2023 (to November 25), with 83 per cent of the koalas dying as a result. These koalas were otherwise in good health.

In comparison, 365 koalas in the entire South East Queensland region are sent into care due to vehicle collision each year. 

“There are horrendous numbers of koalas getting hit and killed by vehicles every year on this relatively short stretch of road, with no reduction in sight,” Dr Schlagloth said.

“We’ve found that because of the amount and the mostly uniform distribution of good quality habitat, koalas are unfortunately killed nearly anywhere along this highway.

“Driver visibility is also a contributing factor. We know that the better or greater the visibility a driver has, the less likely it is for a koala vehicle collision to occur.”

Separating koalas and vehicles is difficult on the existing highway, but researchers believe future avoidance of high-quality koala habitat for highway infrastructure, in addition to constructing or retrofitting protective or diversionary infrastructure – which has already been started by the managing authority in several locations – could help reduce roadkill.

However, initial attempts to separate traffic and wildlife via retrofitted bridges are yet to bring good news to researchers – and the koala population.

“We have monitored three bridges that had been retrofitted with short sections of wildlife exclusion/diversion fencing to encourage koalas (and other wildlife) to pass underneath the road rather than taking the risk of crossing the road proper,” Dr Schlagloth said.

“While rare usage of other, similar structures by koalas has been reported, unfortunately, despite monitoring these underpasses, we have not found any evidence of koalas having used them to get to the other side of the road, while we do have evidence of koalas having crossed the highway successfully and unsuccessfully near those underpasses.”

Researchers said there was evidence that wildlife exclusion fencing may be assisting in keeping koalas away from particular stretches of road (three study sites), but it did not facilitate koala crossings under the highway.

“Maybe koalas will use underpasses over time, or maybe more and longer fencing would be of benefit – further research here is paramount.

“Improving driver attention and their awareness of the potential for koalas to be on the road could also go a long way to reducing the deaths.

“This is most definitely not a sustainable situation for this endangered species.”
Dr Flavia Santamaria, a co-author of these studies stressed: “The Central Queensland koala population is also under threat from diseases like Chlamydia and retrovirus, and opportunities for specialist treatment for injured or sick koalas are not readily available in the region, making it even more important to reduce the number of koala vehicle collisions.”   

Griffith University researcher Dr Douglas Kerlin believed governments needed to step in to protect this koala population.

“Unfortunately, these koalas are not receiving enough protection from the Government. In Queensland, koalas are listed as ‘endangered’ under the Nature Conservation Act, but policies enacted by the State Government are currently focused on populations in South East Queensland, while koalas in places like Central Queensland are largely ignored.

“Similarly, much of the traffic along this highway is supplying mining activities in the Bowen Basin, but the Federal Government Environmental Protection and Biodiversity Conservation Act approvals process has only focused on the direct impacts of industry on koalas, and has largely ignored the wider indirect impacts, such as increased traffic volumes on transport infrastructure corridors.”

Dr Schlagloth also commended the tireless efforts of former citizen scientist, now CQUnversity Honours student, Charley Geddes who dedicated her time to monitoring the stretch of road all hours of the day or night to pick up dead koalas.

“Our understanding of this koala population is down to her dedication … given the level of population attrition caused by the road, this could be a koala population of national significance, one we would know very little about if it wasn’t for her work.”  

The latest studies were funded by the Department of Transport and Main Roads, and researchers believe further funding needs to be allocated to conserving this koala population.

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