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

Foxes would bring disastrous ecological consequences for the island state of Tasmania. That's been stated so often that it is deserving of a fridge magnet.

While we should all be supportive of the intention of any effort that seeks to prevent foxes establishing in Tasmania, there is much more required than good intentions alone. After all, the road to hell is paved with them.

In the scientific equivalent of feeling the width and disregarding the quality, good intentions and programme names containing active verbs can sometimes seem good enough. However, callingsomething an 'eradication programme' is not the same as demonstrating that you have the potential to do just that.

The problem is that I still can't know if there is a free-living fox population in Tasmania or if there ever was. If a fox population is present, I can't know if it is being 'eradicated' either.

The devil, as always, is in the details.

Two known fox introductions, one in 1998 and another in 2001 stand as convincing evidence of 'free-living' foxes once existing in the Tasmanian environment in the recent past. In more than a decade since, the Tasmanian fox eradication programme has not managed to obtain conclusive direct evidence of a 'free-living' fox (ie. one that has perhaps been photographed by trail cameras; freshly killed by shooting; trapped; evidenced by fresh tracks or bait take; confirmed calling in the mating season or by locating a den, cub or a very recently dead carcass etc.).

Of course, the absence of evidence is not evidence of absence – granted.

Yet, given the Tasmanian government's claims of large-scale releases of up to 19 foxes prior to 2000 and thousands of public sightings and the investigations that followed, the dearth of convincing physical evidence has been surprising. Did the big fox release even happen as once claimed? Well, no one actually has presented any evidence for that either. Even the Tasmanian Police agree on that point.

Significantly, there is no evidence that even one 1080 bait has been taken by a fox; something regularly monitored on the mainland to the point of being a prosaic event. Instead, public sightings have been widely used to justify not only the start of the fox eradication programme but also its focus, the status of the assumed population and eradication success. Strangely, from 2003 fox sightings in Tasmania became progressively more common as the media campaign grew.

I'll be blunt. Reliance upon public sightings of foxes to target eradication efforts and to determine control effectiveness is pseudoscientific - and illogical. Public sightings are not scientific 'data' and should never be treated as such. They are unable to be replicated or controlled and without physical evidence located to corroborate them, they are totally useless. Otherwise the thylacine must also abound, not only in Tasmania, but also in mainland Australia where thousands of similar public sightings have been made over the decades. Accept public sightings, without corroboration, as a measure of a fox population, and you can bring the thylacine back from extinction with a similar piece of pseudoscience.

The Victoria government recently took a refreshing and commendably scientific approach to this very problem. Despite many sightings, dubious prints, stories and prey kills that many claim are proof of 'big cats' (pumas or panthers) in south-east Australia, scientists concluded that there just wasn't any reliable scientific data to suggest their existence was likely. The onus now remains squarely with those who make claims otherwise to find some – and that's how it should always be.

Thank goodness the Victorian government did not set about to eradicate big cats on the strength of public sightings, claims and dubious evidence.

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.

To many a discussion about the existence of the Tasmanian fox population seems tiresome given that fox carcasses have been found opportunistically in Tasmania – and they have been. It's a done deal to some. Eyes are raised skywards in disbelief and guffaws resound that such seemingly overwhelming evidence could be questioned. Based on this some throw their full support behind the intention to eradicate a fox population. This is the physical evidence most people point to.

Yet, hoaxing has driven a stake into the heart of reason. Unbridled precaution, especially the tendency to accept any fox evidence as confirmatory, has hammered it home.

Many fox carcasses and 'physical evidence' found in Tasmania (especially early ones) were very crude hoaxes; there are far more than the four now pointed to. All without exception have been provided in suspicious and/or very poorly documented circumstances where anonymity is a frequent hallmark. Even in the most critical cases you must suspend belief and accept backstories where mysterious parties have moved carcass from place to place for dubious motivations. Does this mean I know for sure that they are all hoaxes? Of course not. But the only reasonable conclusion, given the proven tendency for hoaxing, is that an opportunistically recovered fox carcass is not good prima facie evidence of a 'free-living' fox population. The quality of such evidence is not such that it can lead to a scientific conclusion of any merit. I have little hesitation in rejecting it as anything other than an indication that better physical evidence is required.

Only a measure indicating living, breathing, walking, free-ranging or breeding foxes says anything truly useful about the presence or absence of that population as well as the progress towards eradication. I'd even settle for a few good sets of fox prints to go with a multitude of supposedly 'reliable' sightings and fox positive scats – just once in seven years and 10,000 scat specimens. Because while the original Burnie fox left lashings of them in 1998, other Tasmanian foxes seem to be reticent to do so despite being pinpointed by so many Tasmanians. Now that's just weird.

Suspending scientific objectivity to rally to a cause is dangerous, no matter how worthy the cause and how good the intention. To accept any physical or anecdotal evidence of low evidentiary quality is naïve, but also contrary to what science is all about. That's why the Tasmanian fox programme fails as a science-based endeavor because it does not use testable and corroborated data to make claims of its capacity to eradicate. Areas of uncertainty become magnets for poor information, belief, wishful thinking and subterfuge.

The problem is we have sought to eradicate something that we cannot measure. You cannot eradicate something that lurks in the white noise of uncertainty.

But let's be clear once again. Single live foxes have been introduced into Tasmania in the recent past (2001, 1998 and before) and my bet is that they will be again. It will not be by accident when this happens and it is highly doubtful that it was to begin with. So we need to innovate and develop the capacity to detect what we fear rather than fear what we can't detect and do much about. Let's be honest about this for once.

Overall, the real capacity to detect or monitor a low abundance of free-living foxes and then apply a control measure of known and measurable effectiveness has not demonstratively improved in a very long time. There has not been adequate, effective and rapid innovation to this end, even though it has been urgent and necessary.

Sadly, spin that avoids admitting to these obvious inadequacies is bulwarking against the need for change and producing something better for the future. This political kneejerk may eventually backfire quite badly for Tasmania. It ensures that the island state will face its next fox incursion with the very same inadequacies intact and almost certain failure if a multiple fox releases ever do happen.

Spin-doctors have failed to communicate to the Tasmanian people the most fundamental issue, well known to population ecologists, andbest summarized by a few paraphrased words originally attributed to the 19^th century physicist and engineer Lord Kelvin:

"You cannot manage what you cannot measure."

Because if you can't find it, prove that you have killed it or know where it came from, or that it still exists or ever did - can you eradicate it? The answer is clearly no.