Counting Cats Off Familiar Tracks

Sometimes we can be completely oblivious to places just off our usual tracks.

Australia is such a particularly vast continent that it can be somewhat awe-inspiring to consider how much of the country most Australians have never set foot in. Living in one of the smaller states, Victoria, I tend to assume I’ve pretty much seen it all.

So, it was refreshing to have the chance to go on a little exploratory adventure within my own state, in the coastal Glenelg region right on the border of Victoria and South Australia. This is one of those gorgeous places where patches of bush extend to the coastline, and while it’s relatively close to my usual haunts, the area was completely new to me.

Just as Glenelg has been hiding just off my tracks for years, the movements and habits of feral cats in Victoria have been similarly elusive. The impact feral cats have on Australian wildlife is well documented and undeniable, but the situation in Victoria remains somewhat mysterious.

[caption id="attachment_271" align="aligncenter" width="3264"] Some shifty looking feral cats caught mid-meal on camera. Images: Zoï Banikos, Matt Rees.[/caption]

This is partly due to feral cats not being classified as a pest in Victoria (yet), despite recommendations to do so in the Feral Cat Threat Abatement Plan, and the Northern Territory, Queensland, and South Australia already classifying them in this way. This technicality dramatically restricts the work researchers can do, preventing any trapping or radio-tracking of cats to establish densities or home ranges. Trapping cats can be near impossible anywhere, but if a researcher happens to catch one in Victoria they’re obliged to take it straight to a vet or animal shelter, just as you would with a domestic cat.

Another complication is that much of the Australian landscape is currently baited for foxes, and there’s evidence that foxes in turn control cats. So, it may be possible that fox baiting is actually further boosting feral cat numbers in Victoria...

Such a murky situation has led Matt Rees, a PhD candidate at the University of Melbourne with a questionable appetite for cats and caffeine, to embark on a project aiming to investigate cat numbers in these areas. Matt hopes to not only look at cat numbers but to investigate the relationship between cats and foxes. For example, cats may live in different areas to foxes, or they might only be active at times of day when foxes aren’t around.

After arriving from Queensland and being told his grand plans for cat trapping were impossible with the Victorian legislation, Matt has moved to using camera traps for the field component of his research.

Camera traps are just what they sound like – cameras where photos are triggered using motion or infrared sensors – and they are both a researcher’s blessing and curse. They allow for relatively non-invasive data collection from a distance, and over a long period of time. However, it can take many many hours to process the resulting footage. To increase the chances of the target species being seen by the cameras, lures, such as peanut butter baits for mammals, can be used to attract the target species.

So after a day of driving, Matt, myself, and another keen volunteer arrived at our home for the week and started constructing cat lures. This procedure involved us ripping up a horde of oil absorbing material (usually used by mechanics #reviewforscience) chucking it in a bucket and backing the hell away. Then Matt (because after all, it is his project) stirred the material in a wealth of tuna oil until it was soaked through and sufficiently pungent enough to attract a subsequent wealth of cats.

[caption id="attachment_272" align="alignnone" width="3264"] Matt demonstrating a more traditional use of the feather boa, and volunteer Steph preparing the cat lures. Images: Matt Rees.[/caption]

Donning gloves, we then embarked on the decidedly finicky job of fitting these stinking scraps of material into bait traps, which we then lovingly decorated with chopped up feather boas. (Non-ecologists should know this strange mix of craft and DIY is pretty standard in science).

Once we had each cat lure looking as delicately attractive as a cat lure with a feather boa can, we cooked up the traditional pre-fieldwork storm and Matt laid out a laminated map of his camera trap sites, perfectly arranged in a grid formation across the forest.

The cameras were split between two broad areas: areas baited for foxes, and areas without baiting. So, by recording cats and determining their density in these areas, Matt can figure out whether foxes are having an impact on cats – by changing their behaviour or habitat use – and therefore whether fox baiting may actually be heightening cat numbers. Matt is repeating this across other forests in Victoria, to see if he can find any consistent patterns.

So the next day we were out in the forest, attempting to get as close as possible to those points marked on Matt's map. Often fieldwork like this involves long treks with backpacks stashed with cameras, steep terrain and bush-bashing through potentially snake-ridden shoulder-high grass. We had it relatively easy in comparison because we were working in the beautifully flat and accessible Annya State Forest. Apart from one area with swampy terrain and grass towering above our heads, the GPS points tended to lie only a few easy hundred metres off the tracks.

[caption id="attachment_277" align="alignnone" width="3264"] Some of the critters we found: a confused koala, some kind of outstanding platyhelminthes (anyone?), one of many spiders on it's self-made mansion, and some abandoned emu eggs... Images: Matt Rees.[/caption]

Because of this, the fieldwork was mainly bushwalking through gorgeous Eucalypt forest, allowing us to spot a few cool critters on the way. The most recurring were the spiders, including a variety of colourful and spiny species which were surprisingly difficult to spot until you had pretty much destroyed their meticulous web work.

Eventually we would reach a set GPS point (or get as close as the terrain would allow) and start looking around for the perfect tree to mount the camera on. Once the camera was done we set up a cat lure and cleared the vegetation around it to prevent the camera trapping nightmare that is endless video footage of grass waving in the wind.

[caption id="attachment_273" align="alignnone" width="3264"] The ideal camera trap set-up: a clear space (with orchids untouched), one of our specially prepared cat lures, and, of course, the camera. Images: Matt Rees.[/caption]

Once we had checked (and double checked) the camera set-up was perfect, we trudged back through the forest, keeping our eyes peeled for spider webs. Unfortunately we usually failed at the latter, and were often still peeling remnant spider silk off our jackets once we were back in the car. Given a few months, Matt would be back with another car of keen volunteers, heading back into the forest to retrieve all the cameras.

From there, it’s on to processing the camera trap images, counting cats, and teasing out  how each individual moves around in their environment. Matt's endless number of photographs will unearth answers to our questions around feral cats in this forested environment, informing future management of cats and foxes, and further uncovering the mystery of feral cats in Victoria.

Study question: How many cats are out there, and does fox control actually benefit feral cats?

Importance: This work will inform future management of feral cats, and potentially foxes, in Victorian forests and similar environments across Australia.

In a word (almost): Forest ferals!

Read more about Matt’s research on his blog here.