Science is a vixen

May 30, 2016  •  Leave a Comment

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.

Bettongia gaimardi cuniculus (Tasmanian Bettong).  Favorite late night snack of red foxes.Bettongia gaimardi cuniculus (Tasmanian Bettong)<a href="http://bie.ala.org.au/species/Bettongia+gaimardi" target="_self">Bettongia gaimardi cuniculus (Tasmanian Bettong)</a><br/> <br/><a href="http://www.iucnredlist.org/details/2783/0" target="_self">IUCN Status: Near Threatened</a><br/> <br/>The IUCN page for Tasmanian Bettong lists the reason for the &ldquo;near threatened&rdquo; status assessment in 2008 as being due to the &ldquo;recent introduction of the Red Fox&rdquo;. That&rsquo;s not surprising because the Red fox is considered the main culprit for the extinction of the other bettong subspecies (<a href="http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=66656" target="_blank">Bettongia gaimardi gaimardi</a>) on the mainland.<br/> <br/>The fox problem in Tasmania was a huge deal&hellip;. a few years ago. I couldn&rsquo;t recall hearing about it recently so I want digging and what I found blew my mind. It&rsquo;s a story with layers like an onion, and is way too big to tell here, so I&rsquo;ll do a blog entry and link it here.<br/> <br/>In the meantime, enjoy looking at this cute guy and sleep a bit easier. A lot has changed in eight years. In fact they&rsquo;ve even been <a href="http://www.mfgowoodlandexperiment.org.au/bettong.html" target="_blank">reintroduced to the mainland</a> and are apparently doing well.

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:

  • In 1998 a fox definitely made it to Tassie.  It wandered off a cargo ship in Burnie, was captured on video, and footprints were found on the nearby beach.  Attempts were made to find it, but it proved elusive.
  • There were alleged conspiracies in 1997 & 1999 by three hunters to bring fox pups to Tassie from the mainland.  Their plan was to raise and breed them, and then release populations at three disparate locations in Tassie.  Freedom of Information requests show the police investigated, and thought this information was credible, and presented it to the relevant State Minister, and Federal Senator.
  • Also in 2001 a Fox carcass was handed in having been reportedly shot at Symmons Plains.  An analysis of the stomach content deemed the animal has consumed Tasmanian endemic (Pseudomys higginsi).  This was taken as confirmation that said fox had been alive and feeding in Tasmania.
  • In 2003 another fox carcass was found as road kill on the Bass highway near Burnie and handed in.
  • In 2006 another road kill carcass was handed in.  This was also apparently road kill, this time from near Corana.

 

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:

  • Creating a DNA test designed to uniquely identify foxes.
  • Conducting field work using specially trained dogs to find "scat" which was then subjected to that DNA analysis
  • Operating a phone line for reporting sightings, and evaluating the validity thereof.
  • Conducting a 1080 baiting scheme in line with the sighting and scat analysis.

 

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:

  • Physical evidence in the form of carcases and skull handed in.
  • Numerous reported sightings that were evaluated as credible / reliable.
  • Of the ~10,000 scats found, 56 to 61 (depending on timeframe) tested positive for fox DNA.
  • A decline in sightings in areas where baiting was carried out which was taken as a statistical confirmation that baiting was effectively countering an existent population.

 

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.

 


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