I had caught many glimpses of bilbies while spotlighting and processing camera trap images during my internship, but I hadn’t had the chance to experience them up close.
Needless to say, I jumped at the opportunity.
The bilbies in question were hiding out within the Arid Recovery reserve in South Australia. This reserve encompasses 123 km2 of arid habitat, with around half of that being completely feral-free, meaning no foxes, rabbits, or cats. The rest of the reserve is split into two expansions with low densities of cats and rabbits. These expansions provide researchers with opportunities for experimentation, allowing for comparisons between the expansions and outside the fence.
The Greater Bilby, alongside a vast number of our native species, is threatened by feral cats and red foxes. Being a predator-free reserve, much of Arid Recovery’s research focuses on managing this threat.
And while feral cat control is crucial to prevent current impacts on our native species, it is unlikely we will ever be able to completely eradicate feral cats from the Australian landscape. Currently, native species struggle not only from the sheer density of cats but also because some species, particularly populations kept long-term in feral-free reserves, are naïve to the predators. They simply don’t recognise, or are not quick enough to recognise, the threat the cats pose to them.
There’s some chance populations will eventually learn to avoid this (relatively new) predator. Indeed, some species, such as Australian black snakes, have evolved to avoid eating the poisonous cane toad since it moved through their territory. However, such species still suffered major declines when the toad first arrived, and many of our native mammals, like the bilby, are already threatened by other factors (such as habitat restriction). The sheer density of cats is probably enough to push them towards extinction faster than they can evolve to face the threat. So, what can we do to help them along?
How about training them ourselves?
If we expose bilbies to low densities of cats, enough to give them experience with the predator, but not enough to substantially lower their population, could we kickstart the evolutionary process, and give bilbies a better chance outside predator free reserves? Previous research on Burrowing Bettongs (an insane species you’ve never heard of) suggests we can, but perhaps bilbies will react differently.
Enter PhD student Alexandra Ross (hereafter known as Aly).
Aly’s project involves comparing the predator aversion of bilbies from two different populations within the Arid Recovery reserve, one exposed to cats (at a low density) and one not. The hope is that bilbies which have been exposed to cats should have greater predator aversion and therefore greater survival rates once rereleased.
To test this predator aversion, Aly had to observe in the field how long individual bilbies took to emerge from a burrow within a controlled pen. But to do this she needed to catch some first.
The trouble is bilbies are not trap-happy. Unlike bettongs who will stop at nothing to get their hands on a peanut bait, bilbies are much more cautious and so it is practically impossible to survey them by setting out traps. Instead, you must catch them by hand while spotlighting at night.
Aly therefore required bilby chasers, and I was one of them. Our job was to jump out of a 4WD as quickly as possible, sprint our guts out towards a bilby, and manage to catch it safely in a soft felt capture bag. We would then take the bilby to a pen where Aly could conduct behavioural trials to test their predator aversion tactics, before taking them safely back to their capture point before dawn.
Setting out well after dark, we started driving within the reserve, three of us with our arms out the windows waving spotlights back and forth and back and forth. Our eyes searching and scanning and hoping for bilbies, and the moment one appeared…
Hands on door handles, us three volunteers in the back readied ourselves.
Aly slammed on the brakes and pulled the 4WD to a stop, yelling ‘GO GO GO!’. The moment the car halted we threw ourselves outside of it.
Nets in hand, we ran, we sprinted, we almost tore our muscles apart soaring out into the darkness. Adrenaline and instinct drove us on, the first 30 seconds of running we were barely conscious for determination.
The light from our head torches was shining out onto the dirt, sand, and rocks. The edge of our lights caught the flick of a white fluffy tail and we geared towards it, yelling encouragement to each other as we went.
Each time we tried to take some kind of strategic formation, one in the middle and one either side to cut the bilby off. Sometimes it worked. Normally it didn’t. The bilby was too fast, too agile, or disappeared down into a burrow.
If there was a sand dune we tried to cut them off from it. Once on the dunes we had no chance against the bilbies, they danced up the sand with no effort at all, while we slogged up as if our legs are already knee-deep in quicksand.
We were at our best on the swales: the flats in between sand dunes. Ideally the ground would be just dirt or low grass, but occasionally we would be running across rocky gibber plains, dreading a wrong step and an ankle-twisting landing.
It was a lucky break whenever we spotted a bilby close to the road. My first catch was right outside my door when I spotted him but he had deftly darted away by the time we humans were outside the car.
But I ran like absolute hell, not daring to take my eyes away from that tuft of white fur for a moment. We all ran out into the darkness, leaping over bushes and hoping against wild hope that we would eventually wear him out.
Thankfully he ran into a collection of bushes and I and another volunteer were soon onto him and gently placing him into a felt capture bag. Success!
Each captured bilby was kept for the least amount of time as possible to minimise stress, and released in the exact location they were picked up with plenty of time for them to forage and return to their burrow before sun up.
Work like this is essential for threatened species conservation; effectively monitoring individuals and populations is critical to understanding how animals are going and how best to manage their ongoing survival.
Around half a century ago, we lost the Lesser Bilby to extinction. This time around we have so many hard-working land managers, researchers and volunteers trying to save the Greater Bilby. So this Easter (and the next) consider celebrating bilbies (not bunnies) to support their work.
The Greater Bilby is a bizarre, marvellous, and utterly unique Australian species, and it would be a mighty shame to lose it.
Simple study question: Can exposure to cats provide bilbies with the survival skills to live alongside feral cat populations?
Simple study answer: We’ll soon find out! (Research in progress.)
Importance: This work may provide a way to train up our native species to survive despite burgeoning cat populations.
In a word: Training