Forgotten Fauna Part 20: How the fox spread across the Australian continent… and can we train our wildlife to better cope with ferals?

Two interesting things have popped up since last month’s forgotten fauna instalment about the Woylie, that are worth exploring, as they add some additional interesting colour and context to the ongoing story of our forgotten mainland fauna…

The spread of the fox across Australia

Firstly, a couple of weeks ago there was an interesting story in The Conversation, outlining research which used multiple information sources to enable the development of a model that more accurately charts the spread of the European Red Fox across the Australian continent. For more information you can read the journal article here.

One of the primary sources of data for this study, is incredibly interesting research that was published in late 2018, which took the time required to compile accounts of the arrival of the fox (i.e. first sightings) from across Australia, to more accurately map the invasion front of the fox after its deliberate successful release in Victoria in the early 1870s.

In this fascinating study, hundreds of location specific ‘first fox sightings’ were extracted from the newspaper archive (shown below), allowing ‘contours of spread’ to be drawn, charting the rapid movement of foxes (also shown below) from their original release locations near Melbourne. Please click either image to enlarge.

Consistent with the more recent modelling study, these accounts indicate that foxes had successfully colonised most, if not all, of the most ecologically suitable portions of the continent for this feral species by the 1930s, or a period of around 60 years. For a continent of this size, this is truly remarkable, and devastatingly so.

If you are interested to learn more about the ecological catastrophe that unfolded in the wake of this rapid advance, this is a theme I have previously explored in earlier installments of this series of blogs that you can read here:

• Part 3 – The event that changes everything – foxes establish in the region
• Part 4 – Remembering the last Dingo at Mt Richmond… and, why did the fox run rampant?
• Part 5 – So, just how unique is Tasmania’s wildlife?
• Part 6 – The demise of our forgotten fauna… and what do the Fox and Cane Toad have in common?
  

The other thing that really leapt out at me after glancing at the map of Australia, is how significant it is that Tasmania is still coloured white, with its environment somehow managing to successfully resist attempts to introduce foxes there. As I mentioned in Part 18, the presence of direct competition in the form of Devils is hypothesised as a likely key reason for foxes never establishing on the island.

For the integrity of Tasmanian ecosystems, and several species of wildlife that became extinct on the mainland soon after the fox’s arrival, this is incredibly fortuitous. Yes, sometimes positive conservation outcomes have relied heavily (perhaps disproportionately) on luck!

Can we train our threatened wildlife to better cope with foxes?

The second story that appeared in The Conversation, literally just after our last newsletter came out, provided a fascinating update on the trajectory of the Woylie / Yalgi (Brush-tailed Bettong), at the Marna Banggara project site on Yorke Peninsula in SA. The thing that is fascinating about this project, is that it is aiming for the suppression of foxes and cats, behind a fence that is not perfectly sealed (due to openings at roadways), which means that introduced predator eradication is not the goal. This design, which does allow for a degree of slow re-invasion, provides a fascinating alternative case study for threatened species recovery in the presence of a suppressed introduced feral predator population.

Although this might sound counter-intuitive, given the spectacular success of predator-free enclosures elsewhere in Australia, as we explored last month that security for critters inside these fences comes at a significant behavioural and evolutionary cost – that is, the loss of a fear response that over time, makes them increasingly less likely to ever survive outside the fence in the presence of predators.

With this in mind, the Marna Banggara site is offering a highly important ‘middle ground’ research opportunity, to not only see what level of fox and cat suppression is required to re-establish sustainable threatened native mammal populations, but also to see whether these species will positively adapt to the presence of these predators over time, to make them more resilient, in more settings in the future. Unlike the first wave of fox invasion outlined earlier in this story, which unfolded rapidly and without constraint (in the Yorke Peninsula area approx. 120-130 years ago), this time we’d be buying our most vulnerable species of wildlife valuable time to adapt, respond and evolve…. well, at least that is the key theory that is being tested!

The story has an added fascinating experimental ingredient, because multiple source bettong populations were used in the initial re-introductions – each with different behavioural and size characteristics based on their origin. This included animals from both inside and outside fences in WA, and also smaller, more naïve animals from an offshore island population (Wedge Island) in SA.

The study revealed that bettongs from predator-exposed founder populations had a larger foot length (implying ability to escape more rapidly) and greater body weights than those from predator-naïve populations, indicative of potential adaptive benefits for predator evasion and resource competition. Survival rates were initially higher in animals released from populations that had both larger individuals and previous predator exposure.

This study – and future outcomes from the Marna Banggara project – offer valuable insights to all of us who have an interest in threatened mammal recovery – especially achieving successful future reintroductions of wildlife outside of fences. This remains the hope as we look to undo some of the damage done, ever since the fox advanced unimpeded across the landscape all those years ago…

To learn more about this study, please read the Conversation story here (also by clicking on the image below), or you can click here to see the published journal article (available as a pdf) in Global Ecology and Conservation.