HAVE WE FOUND A NATURE-MADE SOLUTION TO FENCING?

The ‘Islands in the Sky’ project seeks environments that naturally fence out predators and operate as safe havens for threatened mammals. The WWF-Australia Rewilding Team have recently returned from Mount Talaterang in NSW, a kind of ‘Lost World’ and a potential future mammal release site. Read on to hear from Rob Brewster, on his four ventures to this rugged and remote landscape to test the ‘Islands in the Sky’ theory.  

The first time I laid eyes on an aerial photograph of Mount Talaterang, I was drawn to the place. Approximately 300 hectares of forest, swamp, creeks, heath, and rocky outcrops – all surrounded by hundreds of feet of cliffs. My intention? To determine whether this remote area is operating as a natural safe haven for native mammals without the need for a 'man-made' fence. 

This is not to say that fencing isn’t effective; by 2025 WWF-Australia supporters will be supporting the reintroduction and post-release monitoring of mammals in over 5,000 hectares of fenced landscapes. But fenced safe havens bring their own sets of challenges. For wildlife, it can result in a loss of genetic diversity within a population, reducing predator awareness over time. Operationally, they’re expensive and require ongoing maintenance. So if we can find strategies that use the same concept, but rather than using wires and posts, use natural landscape features, perhaps we can grow our safe haven strategy.  

A while ago, I came across a research paper (Kimber et al. 2020) on foxes in coastal areas which demonstrated a significant difference in fox densities depending on the region’s geography. 

And so, a theory was borne, and with it, an insatiable thirst to prove whether there are naturally occurring alternatives to fencing. Our ‘Islands in the Sky’ project looks at environments (often treacherous and remote) that are naturally keeping out predators and operating as safe havens for wildlife. The rocky outcrop at the top of Mount Talaterang is one such place. 

The landscape on Mount Talaterang is likely suitable for a broad suite of wildlife, including long-nosed potoroos, southern brown bandicoots and brush-tailed rock-wallabies. But first, we needed to test our theory. Do plateaus that are hard to reach have fewer, or perhaps even no foxes!? We planned and prepared for four trips to the rugged and isolated plateau. Walking there is possible – but extremely difficult. Fortunately, my colleagues at NSW National Parks were also interested in finding out more about ‘Islands in the Sky’. I was offered a piggyback on one of their own chopper missions. They would drop my team off on the top of Talaterang and continue on towards Pigeon House Mountain to pick up their cargo. It would give us exactly four hours to deploy 20 sensor cameras before flying out in the hour before dark.  

We landed in a swamp. Jumping out of the chopper into ankle-deep water was just a small taste of things to come. For the next four hours, the team of WWF and National Parks staff battled its way down Talaterang Creek, slid down rockfaces, pushed our way through burnt scrub and finally emerged on a rocky outcrop where we found a clearing for the chopper to pick us up. But it was only a partial success. We missed out on getting our final six sensor cameras. Inevitably, we’d need to return on foot to set up the rest. After a very wet night camped just below the summit on our second expedition, we managed to get the final cameras out, retreating the following day.  

Returning to retrieve the sensor cameras on our third expedition to the mountain was probably our most gruelling task yet. The plan involved walking in and out over two days, with a campout on the far side of the plateau.   

But it was worth it when the images started pouring in. Quoll after quoll, bandicoots galore, native bush rats. We even captured images of wombats and pondered just how they’d made it to the top of the plateau and survived without a significant in-flow of new wombats. Could this population have been trapped there for millennia? It was truly the “Lost World” we’d hoped to find.  

That's when we realised- not a single fox. Our control site a little over two kilometres away - a more connected landscape on Mount Bushwalker - was covered in foxes. Every night, we’d see them trotting past our cameras. But on Talaterang? Nothing. Not a single fox. Now that’s not to say they aren’t there. Or don’t occasionally make their way up there. But something about this landscape was keeping their numbers right down.    

Our fourth and final mission to Mount Talaterang involved animal trapping to sample the genetics of mammals living on the top. The aim was to quantify the level of isolation of Mount Talaterang’s mammals. To determine this, we needed to take a tiny ear biopsy from animals we trapped. We brought 60 cage traps with us. Our expedition would again piggyback on a NSW National Parks helicopter job in the area.  

Because of thunderstorms and some tight chopper schedules, we were given a single night to accomplish our goal – to catch enough animals to provide a reasonable genetic sample size for analysis. Our traps were dropped into us using a helicopter and two very large bags on a 'long-line' (a cable) suspended from the helicopter. Over an extremely rainy 24 hours, we managed to deploy 60 traps and were able to collect genetic samples from 10 native bush rats.    

So what’s next for Mount Talaterang? We’re still crunching the collected data, but this place could play a special role in rewilding southeastern Australia. This ‘Islands in the Sky’ could one day be used to create source populations of threatened mammals to support reintroductions. And perhaps we’ll locate other similarly suitable plateaus that could be used for coordinated rewilding ventures. Despite the difficulties of getting to Talaterang, the fence created by the cliff line is a permanent one. We’re keeping this ‘Island’ on our radar and will let you know what happens next!