Sydney, May 18 (IANS): A once-thriving koala population is fast disappearing, according to Australian researchers who on Thursday called for action to save the marsupials from extinction.

Researchers from the University of the Sunshine Coast, Queensland, conducted a study in the Fraser Coast region and were shocked to discover a seemingly sudden and unexpected decline of koalas in the area, Xinhua news agency reported.

A public survey by the Tiaro and Land District Care Group in 2003 recorded numerous koala sightings, but the researchers were unable to find even a single koala in the area, suggesting a localised extinction may have already occurred.

"If we keep having these localised extinctions, we'll turn around in 10 years and there'll be no koalas left," researcher Anthony Schultz said.

"It was very surprising. Most of the time, when there is a large decline in population, we can say there was a specific reason for it. There's no obvious trigger and yet there's quite strong evidence for another localized extinction."

As part of the research commissioned by the Fraser Coast Council, Schulz visited the areas that were studied in the original survey to track the koala population, accompanied by detector dogs who are trained to sniff out koala faeces.

"The dogs are able to track scat from up to six months ago, so if they are not able to find anything, it means there have been no koalas in this area at all for the past six months," he said.

The findings surprised the researcher, who considered the area to be quite ideal for a healthy koala population, with a high prevalence of state forests.

The Australian Koala Foundation estimated there are less than 100,000 left in the wild and attributed habitat clearing as the primary reason for the decline.