As I mentioned in my last post, the University of New South Wales (UNSW) and Arid Recovery (AR) have teamed together to explore and potentially improve anti-predator responses in threatened species on the Reserve. Reintroductions of these native species often fail due to a lack of effective anti-predator responses (Moseby et al. 2011). The anti-predator responses of threatened species may improve by exposing them to low predation pressure (four cats and two Western Quolls), allowing for successful reintroductions outside the AR Reserve.
Do you think Sepia (Western Quoll) could pass as a terrifying predator? Credit: Kimberley Solly
As well as taxidermy cats (as above), there are FOUR feral cats scaring bettongs in RLX. Credit: Lisa Steindler
I’ve been involved with many facets of this project during my time at AR. One of my favourite parts is determining approach distances for collared bettongs, which helps establish how aware bettongs are of potential predators and indicates something about an individual’s behavior. The concept is simple. Imagine you’re a bettong who’s never been exposed to a feral cat before. A naive bettong wouldn’t be aware of a predator approaching and therefore would be an easy target. However, if you had been exposed to cats and perhaps even survived an attack by one you would be more wary and harder to approach. This would improve your anti-predator response, making you harder to eat and increasing your chances of reproductive success. We want to know if this process is happening. Therefore we preformed approach distance experiments on bettongs in expansions without predators and compared them to the approach distances of bettongs in Red Lake and the Northern where there are predators.
Determining a bettong’s approach distance requires a strong head torch and stellar radio tracking skills. Bettongs are nocturnal so can only be approached at night. A normal experiment goes as follows. One, drive to a bettong warren where you know a collared bettong lives, attempting to avoid lizards, hopping mice, and other bettongs and bilbies on the road. Two, get your tracking gear out, turn the gain all the way up on the receiver and flip the yagi antenna vertically, listening for a telltale beep that will indicate that the collared individual you’re tracking is nearby. Three, if you’re close enough flip the yagi horizontally and turn the gain down. This is when the fun begins.
I watched Bec’s headlamp bob in the distance, blinking like a distant lighthouse when she walked up and over a sand dune. “Ok channel 17, you’re mine.” I headed straight towards the loudest blip I could hear from the receiver. As I walked I swiveled the yagi from left to right correcting my path to always head towards the loudest beep. That meant I was heading towards the collared animal. I struggled up and over a sand dune, trying not to trip on acacia bushes or fall into a bone-dry mulga tree. As I came over the crest of the dune the beep got even louder, becoming distorted. I turned the gain down and kept moving forward.
As you get closer and closer to the individual it’s important to be constantly adjusting the gain and your direction. You can make more sensitive directional corrections with a low gain, but turn it down too far and you won’t be able to hear the collar anymore.
I heard a farting noise and saw a bettong sprint out from under a saltbush. I had reached the gibber plain in between two dunes. I noticed that bettong didn’t have a collar, but based on the loudness of the beep I knew I must have been getting close. After about 10 meters I looked slightly to my left and saw a pair of shining eyes crouching under a bluebush. “Gotcha,” I muttered under my breath. This bettong did have a collar. He looked at me, slowly hopped out from under the bush and then took off towards my left. The beep became softer as he ran off, so I knew he was the collared individual I had been tracking. I paced out 12 meters from my position to the bush I initially saw him under. My first bettong approach distance, done!
Gotcha! This bettong was trapped and measured but didn't want to leave the bag. Credit: Evan Griffith
You read that right, bettongs fart. And no we’re not talking about flatulence. It’s actually their alarm call, however, it can be very handy to scientists working in the outback. When in doubt, blame it on the bettongs! Occasionally, you’ll be tracking a bettong and the beep will get louder and louder and then fade. This usually indicates the animal is running away from you before you get close enough to see it. The first couple times this happens we follow it again, but after the third time we stop. If you kept going you might walk across the entire Reserve and never see the collared individual! Not seeing the bettong after three approaches is a very interesting result that indicates that they may have a heightened awareness of potential threats.
Even though approach distance experiments can run late into the night I enjoyed every session. Since most outback animals are nocturnal you really can’t get a feel for just how much life there is on the Reserve until you go out at night. From nightjars to geckos, western brown snakes to the stick-nest rats, biblies and bettongs, it is never quiet. Standing on top of a dune, bathed in moonlight and watching the reflection of hundreds of eyes is an experience that should not be missed.
Written by Evan Griffith, ARC and Arid Recovery intern