For the first few years I was in Tassie, the fox problem was a huge deal... a $50M seriously huge deal. However I've not heard anything about it in the last couple of years. So when looking up the IUCN status for bettong reminded me of the threat, I decided to look into where things stood. I wasn't expecting such an intriguing story.
Red foxes (Vulpes vulpes) were introduced to mainland Australia in 1845 so that sport hunters could kill at little touch of home. The foxes then proceeded to chomp through the abundance of small mammals that were on the menu. Many species such as the mainland bettongs retaliated by becoming extinct. Foxes were never introduce Tasmania, and since they are ill-equipped for driving jet skis, the small mammal life in the Island state is incredibly abundant, as is attested to by the amount of road kill. Lots and lots of road kill.
There have been foxes in Tassie - that's not disputed. However like most things in real life, "it's complicated". Here's a brief history:
The ramifications of a fox population becoming entrenched in Tasmania are enormous. Foxes are associated with serious decline in small mammal populations, but are opportunists and will take birds etc. if possible. The only silver lining was the belief that any incursion would have been suppressed by an established competitor: Tasmanian devils. Tragically, in the last few years the devil population has crashed due to the contagious facial tumour disease.
Any response to a fox incursion by necessity must be measured against the risks. State and Federal Governments set up the Tasmanian Fox Eradication Program. Over the years it was in operations it spent somewhere between $35M and $50M:
It is an understatement to say that there was contention and public scrutiny regarding the FEP. There were strong views both in defence of, and in favour of scrapping the FEP. From those in the later group, there were arguments about the validity and volume of the evidence that foxes were present at all. From those with a pro FEP point of view, there was substantial incontrovertible evidence that foxes were present:
Disagreement came about because no foxes were caught or even seen by the field workers in the FEP, shot (or even regularly sighted) by hunters, photographed or filmed. The public began to scrutinise the physical evidence, lack of corroborated sightings, and the improbability that the only evidence uncovered by the FEP was ~60 fox positive scats. This was further undermined, when a fox scat was found on Bruny Island: separated from the reset of the State by 2km of water. Under growing pressure, the Government created a review group with deep and diverse credentials to review the arguments for, methodologies of, and works undertaken by the FEP.
The panel examined the reports of mass fox releases by hunters, and the police investigation thereof. It seems that the police back tracked from their initial position to the pollies and come to the conclusion that there was no credible intelligence to support the story that hunters had released foxes.
Next, they compared the frequency of reported sightings with the volume of reporting in news media through time. They found a correlation, indicating that spikes in sightings followed spikes in media coverage. These spikes happened in months when foxes numbers would be at their lowest, and when fox sightings are typically fewest on the mainland: prior to breading season.
They also looked at the physical specimens handed in, and the analysis / interpretation thereof. The stories behind the discovery of the specimens were often questionable, and didn't match the state of the physical evidence. Further, the original analysis made conclusions draped in "definite" language, where speaking in "probabilities" would have been more appropriate. There is also a history of hoaxing with regard to foxes, so the review panel concluded that only physical evidence obtained through FEP or other rigorous field studies should be considered trustworthy.
Even with the rest of the evidence falling down, at least the DNA evidence would be rock solid, crushing any counter argument like a bowling ball in a hydraulic press. However, there was one critical factor in the DNA statistics that stands out: there were never multiple positive DNA results in the same location. Looking factors like the frequency of fox scats, the success rate of the dogs finding them, the size of a fox’s range, how viable DNA in scats is given the Tassie climate etc. they were able to calculate the probability of not finding at multiple positive scats in any of the field survey locations. It was almost zero.
Staring at a statistical aberration of this magnitude, the panel naturally scrutinised the DNA test. It was designed to test positive for fox DNA, and only fox DNA. However when the panel tested it with a range of DNA from other species, it returned positive for a large variety of animals including many common livestock (pigs and cows), invasive species (rabbit and hares), and native species (including devils). Thus, the most compelling scientific basis for continuing the FEP also fell, and the FEP with it.
For those interested, much more detail is available at the panel’s website: http://www.tasmanianfox.com. I’ve attempted to balance brevity and detail, but the nitty-gritty details are a fascinating journey for those so inclined.
Perhaps the most important finding of the panel is this: that science done for conservation, or wherever it’s used to influence policy, should be of the highest standard and open to scrutiny. I think this is true of government in general, though the exact opposite seems to be the norm.
More thoughts on that another time.