Wily scientific tricks trap foxes

Dr David Dall, CEO of pest-control company Pestat, took a small, anonymous silver spraycan to last month's BioFestival agbiotech conference in Melbourne.

He took obvious delight in watching people's facial expressions when they learned what it contained. Nobody volunteered for a test spray. The can had never been used, but few molecules of its noisome contents, lingering on the nozzle after manufacture, confirmed emphatically that it was not Chanel No 5.

Pestat's new fox attractant -- an extract of fermented chicken eggs -- has an odour so offensive to humans that a short spray into the air-conditioning system would have cleared the conference venue in seconds. But foxes and other canids find it so alluring that they'll travel a kilometre or more upwind to investigate.

Dall said a one-second burst on the soil would attract any canid in the area -- fox, dog or dingo. The trick is to combine it with an edible bait that is ambrosia to foxes, but repellent to dogs and dingoes.

In a video-monitored experiment in the ACT's Brindabella Ranges, at a safe remove from human senses, researchers from the CRC for Pest Animal Control found that in 80 visits by all species, not one dog, dingo or native dasyurid predator took the bait.

There was no poison in the experimental baits, but the CRC's researchers may have found a perfect coup de grace to complement the double-whammy combination of attractant and bait. Delving deep into the old research literature, they exhumed a long-forgotten poison that never made it from laboratory to field. Dall told the conference the poison is selectively and highly toxic to eutherian carnivores, but appears to be harmless to marsupial predators.

Its identity is a commercial secret, but Dall says that, 15 months into a three-year research project, it looks superior in almost every respect to the widely used vertebrate poison sodium fluoracetate, or '1080'.

"It's faster-acting and kills more rapidly than 1080, and seems to be more humane," he said. "The animals go into deep sleep, then into a coma. And, unlike 1080, if a farm dog or pet accidentally takes a bait, there's an antidote.

"It has increased potential for broad-scale application. You can't distribute 1080 baits by air, because of the risk to marsupials like quolls. We expect it will not be toxic to quolls, which would open the way to do aerial baiting to control foxes in national parks and reserves."

But Dall told the BioFestival conference that, despite its promise, the new technological package wouldn't be a magic bullet for the European fox.

The great hope for controlling foxes is the radical immunocontraceptive technology being developed by the CRC for Pest Animal Control. It will employ a genetically modified, canid-specific virus as a vaccine to induce an immune reaction that destroys the female's ova.

"The technological focus has to be on the cause, not the symptoms," Dall said. " We need to lower their reproduction rate, and inhibit the recruitment of new breeding animals to the population."

Trail of evidence

The European fox has been implicated the demise of 24 native vertebrate species across Australia since it was infamously introduced in the mid-1800s to provide sport for hounds and gentlemen hunters in pink.

A similar ecological catastrophe now threatens fauna-rich and formerly fox-free Tasmania. Foxes are being sighted in rural areas in north-eastern Tasmania, and the carcass of a road-killed fox was found on a road in the area last November.

The fox's mysterious arrival in northern Tasmania was initially through to be the result of a chance introduction -- one theory was that a pregnant vixen from Melbourne's fox-infested Docklands region had stowed away in a shipping container and escaped when it was unloaded in Tasmania.

But the Tasmanian Department of Primary Industries, Water and Environment (DPIWE) is now convinced the introduction was deliberate.

While no charges have been laid, an ongoing investigation has given credence to an unlikely theory linking the release of foxes in Tasmania to the federal government's compulsory gun legislation, passed in the wake of the Port Arthur massacre.

There have been persistent rumours in Tasmania that several members of a rural family, or families, in the Launceston area smuggled a number of foxes across Bass Strait, secretly bred them in captivity, then released them into the wild.

According to the rumour, they were seeking to avenge the loss of their right to own guns, or believed they could force the Tasmanian government to restore legal gun ownership in the states to control or eradicate foxes.

Chris Ems, head of DPIWE's Fox-Free Taskforce, which is attempting to eradicate foxes from the island state, declined to comment on the rumoured motives.

But he confirmed the taskforce had "very good information", from independent sources, that several people who were known to each other had brought in 20 fox cubs from Victoria in 2000, and reared and released them.

The task force had conducted an intensive investigation of properties in the Launceston area, but it had been unable to find physical evidence of foxes being bred in captivity.

But the task force now has access to a new DNA forensic technique developed by Canberra University PhD student Oliver Berry, that can identify fox scats. DPIWE helped fund the project.

Ems confirmed that the technique would be used in to help determine the extent of the fox's spread in Tasmania - and could be used to identify the the property, or properties, where the foxes were bred, if DNA residues could be found.

The task force was also involved in developing Pestat's potent new fox attractant, and recently distributed 60 spraycans and poisoned baits to landholders around Tasmania, to determine how far foxes have spread, and to eliminate them.

Tassie tigers too?

DPIWE has helped fund an extension of the research project by Dr Oliver Berry, the Canberra University PhD who developed the DNA test to identify fox scats.

Berry has been working to extend the technology to identify other carnivore species -- eutherian and marsupial -- from their scats.

Fox task force leader Chris Ems said the technology would allow researchers to identify the scats of quolls, the Tasmanian devil and "other marsupial carnivores" of interest, whose status in the wild was uncertain.

There have been numerous sightings of the supposedly extinct thylacine or Tasmanian tiger, particularly in north-western and north-eastern Tasmania, since the last known representative of the species died in the Hobart Zoo in 1932.

Berry's new scat-analysis technique now offers Tasmanian wildlife authorities, with community help, the chance to confirm or disprove claims that the world's largest marsupial carnivore is alive and well.