The Future Of

Skinks | Dr Holly Bradley

Episode Summary

Love lizards? Learn all about the Western Spiny-tailed Skink, a punkish reptile with a penchant for living in log castles.

Episode Notes

Love lizards? Learn all about the Western Spiny-tailed Skink, a punkish reptile with a penchant for living in log castles. 

Sarah is joined by Dr Holly Bradley from Curtin’s School of Molecular and Life Sciences, who shares her research of an elusive skink that’s found nowhere else on Earth except Western Australia. She talks about how a novel use of light technology is helping conservationists to understand the skink’s habitat needs and ensure its ongoing survival. 

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Connect with our guest

Dr Holly Bradley, Researcher, School of Molecular and Life Sciences, Curtin University.

Holly has recently completed her PhD within Curtin’s School of Molecular and Life Sciences. Her research focuses on understanding the ecology of the endangered Western Spiny-tailed Skink (Egernia stokesii badia), to help improve translocation management and conservation of the subspecies.

Her research interests include conservation biology, threatened species management and restoration ecology.

Connect with Holly: 

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Transcript

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Behind the scenes

Host: Sarah Taillier
Researcher, Recorder and Editor: Zoe Taylor
Executive Producers: Anita Shore and Jarrad Long
Assistant Producer: Alexandra Eftos
Social Media Coordinator: Amy Hosking

First Nations Acknowledgement

Curtin University acknowledges the traditional owners of the land on which Curtin Perth is located, the Whadjuk people of the Nyungar Nation, and on Curtin Kalgoorlie, the Wongutha people of the North-Eastern Goldfields; and the First Nations peoples on all Curtin locations.

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Episode Transcription

Jessica Morrison:

00:00 This is The Future Of where experts share their vision of the future and how their work is helping shape it for the better.

Sarah Taillier:

00:09 I'm Sarah Taillier. In this episode, I was joined by Dr Holly Bradley from Curtin’s School of Molecular and Life Sciences. We chatted about the Western Spiny-tailed Skink, an unusual reptile that boasts a punkish spiky tail and has a penchant for living in log castles in WA's Wheatbelt and Midwest regions. Holly and I spoke about how a novel use of light technology is helping researchers understand what makes a skink's home his castle, and ensure the ongoing survival of the species. If you'd like to find out more about this research, you can visit the links provided in the show notes.

Sarah Taillier:

00:49 Holly, reptiles are pretty interesting creatures, but the Western Spiny-tailed Skink is especially unique. Can you tell us a little bit about this punkish lizard?

Holly Bradley:

01:00 Sure. So the Western Spiny-tailed Skink is a subspecies of Egernia stokesii that just occurs in WA. They live in the Midwest and the Wheatbelt region, which is right in the middle of WA, and they look like a bobtail lizard, so a lot of people around Perth might have seen bobtails before. They're about 20 centimetres from their nose to the base of their tail, but they look a little bit different because they have spiny scales particularly on their tail.

Holly Bradley:

01:29 And they're also quite unusual for a reptile because they live in family groups, they're quite social. They all live together in what we call a log castle. This is a fallen over tree or a series of logs that are overlapping together and they all live together there. Unfortunately, they're also endangered so they're at risk of a number of different things, including loss of habitat. In the Wheatbelt, a lot of their habitats already gone, unfortunately, and they're still clearing in the Midwest. And there's things like introduced predators, which is not great. But other than that, not really a lot was known about them, so that's why I did my PhD for the last four years, figuring out some of their basic ecology, like their diet, so what they eat, what eats them, predator management that might need to occur and also what makes an optimal log pile.

Sarah Taillier:

02:23 When we are looking at where they live in those little log castles, in a world first, you've been using a type of light technology called LIDAR to digitally recreate the skink's home. How does the LIDAR work and how will it help with conservation of the skink?

Holly Bradley:

02:41 LIDAR stands for light detection and ranging, and it's a technology... Basically it's a machine and it shoots a series of lasers towards an object and the lasers help measure distance and maps that object. And if you take scans all around that object, you can piece together a 3D model and replicate it on the computer and kind of analyse and take measurements and have a very specific and accurate 3D model of that object. And usually this is done at quite a large scale, so you put the LIDAR technology on a plane or a drone and you fly over a landscape, map a big land form. But we wanted to see if we could take that and use it at a very small scale on the ground and map log piles.

Holly Bradley:

03:27 We took LIDAR technology and scanned all around different log piles or log castles. And we wanted to map and see if the log piles that the skinks do choose were different to the ones they didn't and see if there were any trends. And luckily it did work. We had some success and we found some trends so we created really accurate 3D models, not only of the log castle, but the surrounding vegetation. And we found that there were some trends in what the skinks chose. It made sense because they're colony species and they live in families together. They like the longer log pile, probably more space, more hollows to hide in and have some space from each other. They also like some shade, so some vegetation cover, likely because they're a reptile so they need some areas to thermoregulate, so some spots in the sun, some spots in the shade, also likely to hide from predators.

Holly Bradley:

04:27 But they liked less vegetation cover at the canopy level, so the highest level, which is likely because we found that birds can be an issue. The less perching options up high is probably better for the skinks. Yeah. It's good that not only do we now know that they like log piles, but now specifically what kind of log piles they need. This is useful, for example, in the future if translocations happen, which means moving them away from a threat. We know exactly what kind of log pile we want to move them into or to recreate or at a mine site, for example, if they're restoring habitat from where it's being cleared before, we know exactly what kind of log castles we want to put back to encourage the skinks to also come back.

Sarah Taillier:

05:14 Amazing. And you really paint that picture so well of that technology, just kind of flooding a bunch of lasers over this log. So interesting. What's actually involved? You were just touching on translocation, what's actually involved in translocation and will this method become more prevalent in the future conservation of native animals like skink?

Holly Bradley:

05:38 Yeah, so for my project, I was interested in mitigation translocation. That's a form of translocation where you are mitigating an immediate threat. For example, if there are skinks in a log pile and that habitat's going to be cleared, you're moving those lizards away from that immediate threat to somewhere where it's safe. Now, unfortunately with this kind of translocation, it's very reactive and very quick. And so there's often not a lot of planning involved or monitoring to see if it's actually successful. For it to be an effective conservation tool, there does need to be a high investment of time.

Holly Bradley:

06:14 For example, before you actually move the animals, taking the time to scout and find suitable habitat to put them into. Figuring out the optimal log pile, seeing if there's those types of log piles in that habitat, if there's suitable carrying capacity. Are there already lots of skinks in the place you're going to put them into or feral species? Making sure you've controlled feral cat numbers, for example, in the area that you're going to put them into before you put a threatened species into that area.

Holly Bradley:

06:50 A high investment of time and resources is important. Also, it's important to undertake an experimental approach so that we can improve for the future. For example, reptiles exhibit high homing and movement behaviour after a translocation. Basically, they become stressed and want to flee as soon as you put them somewhere. Trialling different methods, such as... There's something called soft release, which is where you put a temporary fence around the log pile to make sure the skinks get used to the site, settle in their home for an amount of time. And then you take the fence away. You can trial different methods like that for different amounts of time and see if that's effective and continue improving for the future.

Holly Bradley:

07:40 Yeah, we can continue improving techniques and this means that mitigation translocations could have the potential to be useful in the future, but translocation should always be the last option. And the first priority is always conserving the natural habitat of that animal. And unfortunately, at the moment, translocations don't really have great success rates. I did a global study of mitigation translocations around the world and unfortunately less than a quarter reported self-sustaining populations in their papers, so there's not really evidence that it's a reliable tool right now. It has potential in the future, but yeah, there has to be a high investment of time and resources.

Sarah Taillier:

08:29 Sure. You mentioned predators a little earlier as well. And that's something that your research has looked at. You found through your research that the skink's predators like to hunt near mining sites, which encroach on the skink's homes. What are some of the ways both predators and mining sites can be better managed?

Holly Bradley:

08:51 Yeah, that's a good question. For my research, I did a few different trials to try and figure out what the predators were for the skinks. The first thing I did was create plasticine replica models of the skinks and put those out in the bush. And luckily because the plasticine is quite pliable, anything attacks it the bite and peck marks are retained, and then I can through that ID what predators have attacked the models, so what would attack a lizard of that shape and size. That was interesting. And then I also conducted predatory bird surveys. I went out in the bush and saw what birds I could see and also what birds I could see around log piles in particular.

Holly Bradley:

09:31 And then I also put camera traps out in the bush for about three years. So these are cameras that are motion triggered. If I put them near a log pile, I can see what predators move past. But as well as seeing what moves past cameras also had the benefit of I could see their behaviour. So what was actually actively hunting around log piles with skinks. That was really interesting. That helped me build a picture of what predators were out there and what targeted the skink. And so what we found was that corvids, which are crows and ravens, actually actively... There were higher relative activity around log piles with skinks in them, so they seemed to be able to detect the skinks quite well.

Holly Bradley:

10:17 And feral cats seem to be a problem because they could not only capture a juvenile, but they were also capable of capturing and feeding on adult skinks. And unfortunately, because the skinks live in a permanent home in a colony, once a cat finds one, it could quite easily keep coming back every night and finding and wiping out a whole colony. That was interesting, but unfortunate for the skinks.

Holly Bradley:

10:45 In terms of management, the first thing is feral predators control is really important. For cats, targeted and continuous management is important because it's quite easy for if you control the numbers of cats in an area, replacement individuals from surrounding areas can come in and the cats are still a problem, so it's not a short term solution. Continuous management is important. And for the corvids, we found they increased in abundance around landfill sites at the mine site. Even though these are native predators, their numbers can artificially be inflated around sites where humans are and where there's food. It's really important to control landfill sites and make sure that fauna don't have access to any food scraps or potential food sources from humans, so this means that we keep their numbers to natural levels otherwise they can suppress the numbers of all the surrounding prey in the area.

Holly Bradley:

11:57 To give threatened species, in particular, the best chance, controlling not only native predators but feral predators are important.

Sarah Taillier:

12:05 I can't go past the plasticine models that you mentioned. What type of state were they when you would get them back, and how could you tell what had been attacking them?

Holly Bradley:

12:16 The crows were actually quite aggressive. They'd go for the head, the tail and then remove the limb, so you'd be left with kind of just a blob with lots of indents. It was mostly corvids that did attack the plasticine so it was pretty easy to tell because they all look the same, but that was the benefit of the cameras as well. I had some cameras out there with the plasticine, so that also helped me ID what would attack them.

Sarah Taillier:

12:46 So where were you actually travelling out to to be able to do this work?

Holly Bradley:

12:49 This was in the Midwest. I conducted all my field work on a mining tenement, so that was about a 50 kilometre stretch of pockets of habitat where the skinks would live. I put the plasticine at sites where log piles were and without log piles to see if predation levels would differ.

Sarah Taillier:

13:10 Wow. It's so interesting. I can just imagine you examining them and just having these little mangled bits of plasticine to work with at the end. The State of the Environment report was released in July and it painted a pretty grim picture of Australia's environment. For example, and you are well across this, we have the worst mammal extinction rate of any country in the world and we have more foreign plant species than native. As a conservation biologist, how do you feel about the future of our native flora and fauna?

Holly Bradley:

13:46 Well, I think that acknowledging the state that our fauna and flora's in is an important step in addressing the issue. And as you mentioned, the state of the environment report was a good wake up call for us to know that our fauna and threatened species are in a poor and deteriorating state, unfortunately, and increased monitoring and investment are needed to protect many of our threatened species and ecosystems. And whilst this is a concerning state for our environment to be in, it does give me hope that this will promote an increased awareness and dedication to conservation.

Holly Bradley:

14:27 And every small action helps. Even if you're not a conservation biologist, anybody can plant trees and plants in their own gardens and help create habitat corridors or even food plants for threatened species. Pecans are a good tree that can help feed our threatened black cockatoos or even looking into local initiatives or tree planting days in our local area. Everything helps. And I think one important thing is educating yourself and doing research and educating yourself on important issues and how to work together to fix them is an important step towards taking informed positive action, which I think is the way forward.

Sarah Taillier:

15:14 Holly, you've previously worked as a sloth technician. Tell me more about this role.

Holly Bradley:

15:19 Sure. When I finished my honours research here in Perth, I was hired as a sloth technician and I went over to Costa Rica for a year and worked there. And so this role was to our knowledge, some of the first research into if a sloth is injured or orphaned and rehabilitated, can it be released back into the wild and be wild again? It was a team of international biologists. We all came from all over the world to work with the sloths and there was a big release cage in the jungle, so it matched almost canopy height. The sloths could get used to the jungle for an amount of time until they were ready. And then we would open the cage door and they could come and go as they pleased. And then hopefully over time they travel further and further from the cage and don't need us anymore.

Holly Bradley:

16:10 And the sloths had radio collars. We put collars on them so we could radio track them through the jungle, and they were nocturnal so we worked at nighttime. And so each of us were assigned a different sloth for a few hours each night and we'd track them through the jungle and then observe their behaviour. And we'd also observe wild sloth behaviour and then compare the two and see if the release sloths were acting like wild sloths.

Holly Bradley:

16:35 And it wasn't all easy. It was a jungle. It was a lot of heavy rainfall and mud up to your knees, and nighttime work on your own, and I even got stung by a scorpion the size of my hand at one point, which was a bit scary, but it was also amazing because being in the jungle for that amount of time, I got to see so much wildlife. You'd be surrounded by fireflies. And there were toucans and capuchin monkeys and coatis and tamanduas which are type of fluffy ant eater that climb in the trees. And they were pretty special. And even some mornings, if you were lucky enough for your sloth to go down to the beach, you could watch the sunrise over the ocean, which was pretty special. But yeah, it was exciting to be a part of research that could help us understand about rehabilitation and release better to help sloths become wild again.

Sarah Taillier:

17:30 Wow. From the jungles on the other side of the world to traipsing around outback Midwest, you have seen some amazing places. So many great conversation starters for a barbecue.

Holly Bradley:

17:42 Yeah. And they're pretty different.

Sarah Taillier:

17:45 Absolutely. Just circling back for a moment, you've mentioned a couple of times that the Western Spiny-tailed Skinks are social creatures. What does that actually look like?

Holly Bradley:

17:57 We don't know how many live together. I saw up to six in the Midwest, but for Egernia stokesii in the middle of Australia, they can group together up to 17 individuals, but it means in their log pile, the permanent log pile that they call home, they all live together and reside in that same space and it's usually related individuals. I saw mum, dad and a few babies living together.

Sarah Taillier:

18:26 Are there different kind of areas in the log castle used for different things or is it all just kind of sleep zone?

Holly Bradley:

18:36 I didn't study it, but from what I saw, they had different hollows that they could sleep and rest in. But the one distinct thing was that they'd have a latrine pile outside the log, so they were pretty clean and they'd all go to the toilet in the same place.

Sarah Taillier:

18:50 How sophisticated. And so the technology that you are using, this LIDAR technology, given you've been able to find these trends for such an interesting creature, what are your hopes for how this technology might be able to be used in this space?

Holly Bradley:

19:06 Yeah. So the idea was to use the Western Spiny-tailed Skink as a case study to see if it was effective. And yeah, luckily we did find trends, so the hope is for the future that it could be used for any threatened species, which is hard to observe and understand. For example, rock pile habitat which might look the same to us, but if we map it, maybe we can find different trends or even cave habitat that different threatened bats might use. The hope is that it can be effective for the future in figuring out the very specific needs of threatened species.

Sarah Taillier:

19:40 Holly, what actually inspired you to become a conservation biologist?

Holly Bradley:

19:45 I think it was because growing up, I grew up in the [Perth] hills surrounded by wildlife. Things like brushtail possums and quenda were in my backyard. Being surrounded by it meant I got to appreciate it. But where I grew up, I also saw a lot of loss of bushland and wilderness, so I was also very aware of the need to conserve it and that's something needed to be done.

Holly Bradley:

20:12 Conservation biology is all about the protection and preservation of the bush and biodiversity, not only to help reduce the loss of our threatened species, but also to make sure we have resilient and healthy ecosystems as well as healthy and improve the wellbeing of our own human communities. I was always interested in the outdoors and working outdoors with wildlife, but I was also always interested in applied research. Research that has on the ground conservation and management outcomes too.

Sarah Taillier:

20:49 Thank you, Holly, for coming in today and guiding us through your fascinating career and research and the lives of some equally fascinating creatures.

Holly Bradley:

20:59 Thank you very much.

Sarah Taillier:

21:00 You've been listening to The Future Of, a podcast powered by Curtin University. As always, if you've enjoyed this episode, please share it and don't forget to subscribe to The Future Of on your favourite podcast app. Bye for now.