Study raises concern over fox sightings

A SCIENTIFIC report has cast doubt on Tasmania’s use of anecdotal fox sightings to justify its fruitless 14-year hunt for the pest.

The report, published in Conservation Biology, found the number of fox sightings recorded in Tasmania directly correlated with unsubstantiated statements made by a taskforce set up to stop foxes gaining a foothold in the state and subsequent media coverage.

The peer-reviewed paper, written by six authors including Tasmanian veterinary pathologist David Obendorf, found the reporting and subjective assessment of these uncorroborated sightings may have contributed to the “flawed assessment” of the presence of an invasive species.

The report says anecdotal reports were heavily relied upon in the first years of the taskforce to justify an eradication program, which used 1080 baiting.

That baiting program was later expanded to the entire island.

“Our results suggest that anecdotal sightings are highly susceptible to cognitive biases and when used to qualify a species presence can contribute to flawed risk assessments,” says the “Accounting for Trends in Anecdotal Fox Sightings” article.

“Data of known quality and precision is required to reliably confirm a unique invasive species incursion.”

In 2001, it was widely reported that red foxes had been deliberately released in Tasmania. That claim was later shown to be baseless.

“Regardless, by 2013, a total of 3153 anecdotal fox sightings had been reported by members of the public and this implied the wide distribution of foxes,” the report says.

The number of sightings ranked as reliable by the fox program in any year decreased as the total number of sightings increased, and showed an “observer-expectancy bias”.

There were 215 fox sightings in Tasmania between July 2013 and March 22 last year — two years after the taskforce was scrapped and when media reports about taskforce activities had all but ground to a halt.

“Between 2011-2013, a monthly media index for foxrelated stories was significantly linked to 15 equivocal claims of physical evidence used to support the existence of a fox population,” the report says.

Co-author Clive Marks, of Nocturnal Wildlife Research, found there had been little critical assessment of anecdotal information as part of an “evidence-based approach for confirming invasive species incursions and directing eradication efforts”.

The fox taskforce, which spent about $50 million in state and federal funding, was disbanded in 2014. A fox watch and act team is now part of Biosecurity Tasmania.

Tasmanian MLC and fox sceptic Ivan Dean has taken his concerns about the eradication program to the Integrity Commission.