How did the koala cross the road?

It sounds like an Aussie joke, but getting koala safely past the traffic is the subject of a world-first study, which has tracked wildlife movement in unprecedented detail.

The research confirmed that koalas were making use of a series of retrofitted underground passages in Brisbane, designed to help the animals cross roads safely.

Suburban traffic is predicted to increase in southeast Queensland over the next few decades, threatening koala populations. The experimental crossing tunnels, known as eco-passages, were implemented by the Queensland Department of Transport and Main Roads, who also funded the study.

The research team, based at Griffith University, used a “world-first” combination of technologies to track individual koalas over 30 months, uncovering the animals’ road-crossing habits in surprising detail.

As Darryl Jones, co-author of the paper, explains, it was previously unknown whether the structures were even being used.

“We expected the animals to take a while to get used to them,” Jones said. “I was the first sceptical person to say they’re not that smart.”

The unbelievers, however, were proven incorrect.

“To our great surprise they were using them three weeks into it. Can you teach koalas new tricks? You can – that’s the point.”

The study recorded the crossings of 72 individual koalas at six sites across Queensland, from Kallangur in the north to Redland City in the southeast.

Over the 30 months they recorded 130 crossings made by 21% of the monitored koalas. Of these, 41 crossing koalas were confirmed to have used the retrofitted eco-passages, with the possibility the usage was even higher (a percentage of crossings were excluded based on lack of evidence).

The findings, published by the CSIRO this week, are based on data collected by motion-activated cameras, GPS collars and newly developed wireless identification tags that allowed the team to distinguish between individual koalas.

“This is all about trying to make absolutely sure that koalas are using some of the structures we’ve put out for them to get safely under roads,” Professor Jones said.

The research shines light on the effectiveness of structures, which can be a significant financial investment for councils.

“All over the place on the Gold Coast and in Brisbane, there are special koala specific tunnels and ledges that are allowing [koalas] to cross. Those animals are not going to be hit anymore, so that’s good news.”