A problem of cunning tasmanian foxes or much less cunning innovation?

Eradication too requires scientific evidence and data – not just good intentions and belief. You must be able to reliably measure fox population changes relative to the application of your control method(s) to see if it can even be done. Eradication cannot be assumed to have occurred by the absence of evidence, especially if a programme is predicated upon equivocal and missing evidence to begin with. At the very least, you need to measure some index of control effectiveness in the field (eg. fox bait uptake maybe?). Otherwise you cannot even know if your control method might work.

It's common sense, not rocket science.

Which brings me to the scat DNA test that is said to describe the Tasmania fox population and largely justify the eradication program. Many people find it the most convincing of the evidence on hand that a fox population does indeed exists in Tasmania – and I agree, but only so long as it is subject to normal scientific precaution. I'm worried that this has not been the case.

From a pool of some 10,000 possible fox scats collected over seven years, some 63 (at the time of writing) widely spaced scats have been determined by the Canberra laboratory to come from a fox. Firstly, these few and dispersed samples might suggest that fox scats cannot be efficiently located and consequently scat detection is not a very useful monitoring technique. Foxes may be all over Tasmania by implication if this is the case. Alternatively it may be indicative of field or laboratory contamination or other error that no body knows about. That would sure account for how a fox-positive scat turned up on fox-free Bruny Island. It's just a little bit strange to find a single fox scat on an off shore island. Just as it's a little strange never to have found corroborating physical evidence very close to any fox positive scats or even two scats from the same fox.

So, I'm waiting for the eradication programme to confirm that the scat DNA technique is infallible and a fox has indeed made its way to Bruny Island and then disappeared. The conservation implications of this for fox free Australian islands are nothing short of extraordinary and demand analysis. Because it would mean that many Australian islands won't stay fox free and this is a disaster. But, if so, how come many islands with far narrower sea barriers than separate Bruny Island and Tasmania, sometimes surrounded by a peninsula full of foxes (eg. French Island for instance), have remained fox free? Otherwise it might seem to indicate some fallibility and error in the scat DNA results, which I feel is very likely in this case. And how big is this error overall; enough to explain 63/10,000 positives?

But let's put the issue of the reliability of scat DNA results to one side and look at two more practical and seldom discussed issues that have escaped any real public debate. They are at least as important.

Many (if not most) of the 'fox positive' scats took some 4-12 months to be analysed from scat collection to result. Hence, foxes can be born and disperse within a period of time shorter than that time take from scat collection to DNA analysis in many cases. Furthermore, a remarkable 60% of fox positive scats were quite recently reported to have been collected in 'urban' habitats, and not routinely followed up with baiting or any control response.

Taken together, this does not sound like the timely information and rapid response required for an effective 'eradication' strategy!

While 60% of these putative fox scats have been found in urban and peri-urban habitats, no other clearly corroborative physical evidence has been. According to the Tasmanian government that's because foxes can live among people and remain undetected by all but a few who see them. That's due to the cunning of foxes according to those running the programme. But that's quite a disingenuous position. You can't rely on the public to turn up evidence for you and physical evidence of foxes is certainly not impossible to find if you go looking where recent scats are found or genuine sightings are made. If the programme wants to claim this is not so, I suggest an experiment on the mainland is not before time.

After all, it's the physical evidence (or even a real fox!) found after competent and science-based investigations, that matters. If you can't find the physical evidence you can't really say that foxes are there, just like you can't say big cats abound in Victoria. Nor can you say that the scat DNA evidence of foxes has been corroborated by evidence of an actual fox that it is said to correspond with. Unless, that is, you believe that the scat DNA technique is 100% infallible from collection to result? If so, why not state this? The implications for other Australian fox free islands are nothing short of extraordinary if you do.

But if you're the sort of person who's more inclined to believe that because big cats are cunning, mobile and at very low density, the lack of physical evidence in Victoria just doesn't matter to you. Because you care more about what you want to believe than what the evidence suggests.

Everyone is capable of confirmation bias. The more firmly you are invested in an outcome the more you may look for evidence to support it, rather than to objectively test your own cherished ideas. You're not an objective arbiter of your own beliefs, despite what you might tell people. Science, unlike superstition and some government policy it would seem, should change when new evidence is found – or not found. If there is an absence of evidence or necessary corroboration, this should be honestly admitted. However if you strenuously control the media message to support your 'belief' and oppose and obstruct other reasonable and independent explanations, then at the very least, let's not call it science.