Kia Pākiki Canterbury – pest control and Predator Free

In this Kia Pākiki Canterbury podcast, Science Communicator Tom Goulter and co-host Associate Professor Adrian Paterson from Lincoln University interview Professor James Ross from Lincoln University.

They discuss topics such as James’s work in pest control, the Predator Free project and Zero Invasive Predators’ predator behaviour enclosure.

Kia Pākiki Canterbury is a monthly podcast presented by the Canterbury branch of the Royal Society Te Apārangi.

Transcript

Tom Goulter

We’re here with James Ross. Professor James Ross is co-director of Lincoln University’s Centre of Wildlife Management and Conservation. He’s Improved Toxins and New Devices champion in Biological Heritage New Zealand’s National Science Challenge, and he sits on the technical advisory groups for Taranaki Maunga, Pest Free Banks Peninsula and Zero Invasive Predators. James, how’d you get into this work?

Professor James Ross

Initially, my first 5 years out of school, I worked for a bank, so I had the unfortunate distinction of my best subject was financial accounting. I arrived at Lincoln University and started off as a parks and rec student. I was looking for something that had some inside, outside, and as more of the ecology subjects started to come online from second and third year, started to find them more and more interesting. And then I suppose it came into the whole conservation thing. You reach a fork in the road where it’s kind of like do you want to count things or do you want to kill things?

And at that point, the killing thing appealed more to me. Some of the tech that was starting to come on board, so some of the aerial control stuff. It was early – with using helicopters and bait buckets, early GPS technology, was pretty exciting. With some of the early days, it was like Campbell Island, 10,000 hectares offshore island in New Zealand. We’ve just taken rodents off them.

There were some pretty cool things that were starting to happen around that time, and I think that was that enthusiasm was the thing that originally drew me to that. Like we’ve got all of these great stories about Little Blue, the Chatham Island robin, and clearing things off Breaksea Island. The breakthrough was Breaksea Island and then Kapiti Island. And there was always going to be a point where we ran out of those offshore islands, and can we do something similar on the mainland? And that’s what’s kept me involved and interested in it.

When I started, most of my work was possum-focused because it was around bovine TB. OSPRI had money. They’re still working towards their eradication of bovine TB by 2040. They’re going to try and do it 10 years earlier than Predator Free is going to do it. And their early stuff was around optimising aerial control and investigating alternatives to aerial control. So can we do more ground control more effectively, more cost-effective?

The Predator Free really was then bringing in other species, and it was probably the response to a Parliamentary Commissioner for the Environment report around battle for the birds, saving our birds. And it said that we’re losing the battle, and particularly in beech forest, large tracts of native forest, and that we need to do something about it. What then happened after that was an injection of private funding. And that’s kind of changed it a lot, actually. So that my early work I would have either done on my own or I would have worked with one of the CRIs, whereas now I work a lot with privately funded organisations, and they work quite differently to CRIs, not surprisingly. Their attitude would be that how we used to do things was too expensive and too slow. And so they’re kind of looking at conservation in a business way. How do we get maximum gains for minimum amount of effort?

Associate Professor Adrian Paterson

Just to make it obvious, CRIs are Crown Research Institutes, which are essentially the government’s science arm, which are about to change and be merged.

Professor James Ross

I don’t have a lot to do with them. I mean, the Crown Research Institutes also won’t fund PhDs. And so the biggest challenge that we face now is finding money to fund postgrad students. And so a lot of these places, another one I work with is Banks Peninsula Predator Free, they’ll provide logistical support. They’ll do big expensive trial work with you, but they generally don’t have the money to fund like stipends. And that’s always a challenge is we can always get lots of students, but how do we keep them all fed?

Tom Goulter

Tell us a bit about the work of Zero Invasive Predators.

Professor James Ross

Yeah, well, they were an interesting one, and it’s like, so they’ve just had their 10-year anniversary at the university. And when they set up back in 2015, they started up with private money. So there was a couple of wealthy Kiwis, and they set up a thing called the NEXT Foundation, and they put down 100 million of their own dollars basically into it, and one of them was the research arm of that, which was Zero Invasive Predators. And their thing was all about we think we can remove stuff, but how do we defend? And so how do we defend that scale? So we’re talking over 10,000 hectares. And so most of the work that they’ve been doing has been around that work.

Tom Goulter

Because it’s one thing to remove predators from an area, but keeping an area predator free, that’s a whole different challenge again.

Professor James Ross

Yeah, well, they like to come back. We kind of had good technology for things like possums already, getting rid of maybe high 90s, but getting those last few. So a lot of their work has kind of been more around the barrier technology but then also how do you find them when there’s only a few of them left in large areas is also a big part of their theme as well.

Tom Goulter

Can’t fence everywhere off.

Professor James Ross

Well, they didn’t want to use fences. That was part of their other one. So their early work up in the Queen Charlotte Sounds – they had a 400 hectare area called Bottle Rock – was they originally looked and said, “Could we trap the peninsula?” So we would set up a virtual barrier of traps about 2 kilometres wide, and could we use that to stop animals coming back onto the peninsula area after we’ve removed them all.

Associate Professor Adrian Paterson

And so by virtual barrier you’re kind of meaning it’s not a fence.

Professor James Ross

Not fenced. Yeah, it’s not a fence. But essentially, they were lines of traps, and their big thing initially with that was that the cost of servicing all those traps just wouldn’t work. So their big thing was around wireless communication, so when a trap was activated, you only then go and service the trap. And they thought that that was the way forward, and it reduced their labour costs by about 90%. And so a lot of the early work was that, and a lot of their earlier work, too, was around geographical features that would prevent animals from reinvading. So their next big site in the Perth Valley, South Westland, is surrounded by the Southern Alps and two major river systems. Early work they found was that possums didn’t seem to like crossing across rivers. And in another study with genetics, we found that possums living on one side of a river, they were using the bridge, so man-made structures basically, to move backwards and forwards, and you could find the relatedness around the bridge.

Tom Goulter

Tell us about the status of the Predator Free 2050 mahi.

Professor James Ross

There’s still 18 projects, but I don’t know, you probably heard, so the Predator Free 2050 Limited, the government company, has been disestablished. So the management role of that now will go back to the Department of Conservation, which was kind of sad because they were great to work with and 10 people lost their jobs. Early on from them we actually funded a couple of our PhD students with Predator Free 2050 money, and they were great to work with. I don’t know how the new management will work, but the projects themselves are funded through until 2028. So Predator Free Banks Peninsula is funded through until then, and they see themselves as operating as they have, waiting to hear what will happen in terms of the oversight management side of things. So I think they’re good. I communicate with them regularly, and they’re motivated and keen and passionate about what they’re doing and very keen to keep pushing and advancing on what they’ve done. So the Banks Peninsula project, they’re looking to remove possums off 10,000 hectares of Banks Peninsula, the wild side. It’s a very ambitious project, but they actually now have got over 300 landowners.

Associate Professor Adrian Paterson

So the wild side is mostly from sort of Akaroa over to the east, I guess.

Professor James Ross

Yeah, so think of it over that side. Le Bons Bay and actually – and in Akaroa as well. We’re about to do another research trial now where they’ve almost completed the 10,000 hectares. They’ve got traps and infrastructure in there. Now we’re moving to the how do we defend that area? How do we stop new animals from coming into that area?

Associate Professor Adrian Paterson

Have you got any clues?

Professor James Ross

Yeah, there’s a few. I still think though it will be difficult to do without some form of a barrier, and even if it’s a leaky fence. So if we think of the traditional predator-proof fence at 1.8 metres tall, it’s designed to keep everything out. What we’re really looking to is preventing, in this case, possum and rodent reinvasion. And so some of the early work we did with Zero Invasive Predators found that we could do that with fences as low as 800 millimetres. And so even if the odd animal gets through, if we have a good enough surveillance system on the other side of it, we should be able to pick them up before they can establish and start breeding. So to me, it needs a leaky, some form of a barrier that you can then work to that barrier and then defend behind the barrier.

Tom Goulter

What predators are the most common in Waitaha Canterbury?

Professor James Ross

I’m amazed in Banks Peninsula how many possums we’ve been pulling out. Certainly, possums and rats would be the big ones over that wild side area. But if you go out to the other area we work on is Birdlings Flat. The main thing we pull out of there is hedgehogs, weasels and mice. Quite different. Possums are a rarity.

Associate Professor Adrian Paterson

So hedgehogs is probably something which might surprise people because people seem to love hedgehogs. And yet they’re probably often public enemy number one when it comes to this, the impacts that they have on an area. And yet they’re quite late to the party from a research point of view. We’re only really just getting going with hedgehogs.

Professor James Ross

Early research like in the braided river areas, if we’re thinking, identified hedgehogs as major nest egg predators. So when they were looking at black stilt recovery, the thing that they noticed was the things that killed the adults were cats and the things that stole eggs were hedgehogs. They were your top two. And people started to look at that.

Quite recently, we started to kind of even look where hedgehogs are. They’re right up to the alpine. They’re in every habitat. And they’re hibernating up in the alpine. They’re not moving back down again. They’re staying up there and they’re breeding up there. And so I think people underestimate how much of an impact they have. They’re almost like little vacuum cleaners. We don’t know a lot about their biology. We don’t know where or why they hibernate, what drives that. They disappear.

We find it difficult to monitor them. Like we tried to do a mark recapture exercise around Kaitorete, Birdlings Flat. We marked about 20 hedgehogs and went back with 30 people 2 weeks later and couldn’t find a marked hedgehog. They are increasingly difficult, and the old adage in our thing is if you can’t monitor them, you can’t manage them. And so quite often it’s like trying to understand more.

But getting funding is one, and that’s kind of – so some of the backlash to Predator Free 2050, and this is happening at the moment, was that we should add other species to the list. I think we shouldn’t. I think we should focus on what we’ve got and then target them. Certainly, I can understand some of the backlashes with the focus on possums, rodents and mustelids, as we’re forgetting things like feral pigs and deer, and you’ll get a lot of other people starting to complain about deer are becoming an increasing problem. Pigs are becoming increasing problems, and I can understand that. The other big push recently has been around cats, feral cats. And if you’re doing control in an area where there’s people, which is what they’re doing with 300 landowners over on Banks Peninsula, they’re going to have cats.

So how do you manage that relationship is quite important. Most people would agree that what we’re doing is good and they would say protecting native species is a positive thing. The argument is around the choice of control tool, and that’s always where the controversy comes in. And you’ll get some people that are always going to be anti-poisons. And there are a lot of different things that you need to consider when you’re looking at control tools around non-targets, selectiveness, same kind of thing. Animal welfare is the one that pushes it, but then also there’s by-kill of things that are valued by people – game animals or domestic animals. You need to factor in that. It’s tricky to please everybody.

Tom Goulter

Tell us what goes on at Zero Invasive Predators’ predator behaviour enclosure.

Professor James Ross

Sure. Well, one of the good things they have there is a large outdoor observation pen. So we have a 2 hectare outside pen. It’s got a predator fence around it that’s turned inside out, so it prevents animals from getting out as opposed to animals getting in. And the thing that we’ve been doing there is around these multi-kill traps is combination lures. How do we attract animals consistently to traps? You get the easy ones early on. How do you then get the ones that are a little bit wary or naïve, or not naïve, but wary and avoidant, neophobic, I suppose you could say? And so some of the work we’ve been doing is looking at combinations of audio, visual and social lures. So audio, we play a possum sound. And we found like we tried aggressive, we tried come hither. We tried all of those ones, and we found that aggressive possum – we had distressed possum, that seemed to drive them away.

Associate Professor Adrian Paterson

Not too surprising.

Professor James Ross

But aggressive possum seemed to work, but there might be some seasonal behaviour there as well. It works better at certain times of the year. In terms of the visual, any light source seemed to work with them, but the social one is the one we’ve just finished working on, and we’ve been looking at – so this is attracting possums to cage traps and which ones they go in. And we’ve looked at using urine and poo, and we’ve also used possum tails, we’ve used bedding material. We’ve looked at a whole combination of are those things important in a combination?

And we’ve even got into the new one with – and it’s really difficult to design a trial to do this – is scent lure, scent trails. So are possums, that are primarily nocturnal, following scent trails left by other animals? Trouble is in doing that in a pen trial is how do you remove the scent trails and set it up for the next trial when the animal’s been running around everywhere. But we’re also thinking about fake trails. So why we’re interested in that is that when we first started doing the thermal camera work, and we would have it set up looking at a chew card, animals would just walk past it. Wouldn’t interact with it. And we think, oh, well, our traps aren’t very good or our chew cards aren’t very good. All of a sudden then maybe a mouse or a hedgehog turned up to that chew card, and then next night a possum turned up. Then next night more rats turned up. And it was like, OK, how do we establish these scent trails so that they make these devices more attractive? So that’s some of the work that we do in with the outdoor pen work with Zero Invasive Predators.

Associate Professor Adrian Paterson

Might be worth just talking through some of the tools that you use.

Professor James Ross

Yeah. Well, it’s come a long way. If you think 10 years ago, we were using chew cards and tracking tunnels, and then it went to trail cameras. Trail cameras would probably be the one I use the most – basically what we call passive infrared cameras, so they detect movement. So if something moves past them, like if you jump up and down outside your floodlight outside, it detects that you’re there and switches on. And we can use those as a non-invasive way of trying to monitor where animals are, and we can have lured sites that we attract them to and use that as a monitoring tool.

When things get really low, numbers get really, really, really low, now we’re starting to work towards thermal cameras. So thermal cameras, what’s the difference? They’re on all the time. And all they’re looking for is a heat signature. And they have a much wider view. And so we’re increasing the sensitivity of our monitoring tools. What the next stage is, and we’re trying to get there now, is self-reporting cameras. So a camera that detects something has the ability through AI to identify it and then report it back. So we get instant real-time surveillance. And probably I think what we’ll end up with is our ultimate tool will be a kill trap, which also monitors and reports back – I’ve killed 10 possums this week, I’ve seen two that didn’t go in the trap – and then you can work the management response to that.

Associate Professor Adrian Paterson

There were three weka that put their heads in the trap, and I didn’t kill them.

Professor James Ross

Non-targets is the big thing, and that’s like what a lot of people don’t think about is that traps catch non-targets as well. And so our response to that with some of these early multi-kill traps that we have out now, like the AT220s, which target possums and rats. They can do 100 kills. They have little lure dispensers that are putting out lure every day. What if a non-target turns up? And our response to that previously is we only have them on at night, OK, and that way then we can’t target birds.

They are looking around AI now to distinguish between target and non-target. The thing about AI though is it does require a lot of training, and it generally is site-specific. So they trained an AI algorithm to detect cats in photos from the Auckland Islands. They brought it to New Zealand Hawke’s Bay, and it fell over. It just wouldn’t work. And it’s completely different habitat, different background, different everything. And so I think AI does have a lot of potential as a labour saver, but you have to actually be prepared to commit to the training side of it. And that training is ongoing. And look, there’s citizen science opportunity there too. There is a lot of people that love to go on sites and identify photos for you free of charge, and I don’t think we should undercount the role of citizen science in something like that as well.

Associate Professor Adrian Paterson

Talk us through the process of how you get approval to do these types of things.

Professor James Ross

Well, for kill traps, it was like initially anyone could put a kill trap out on the market, and there wasn’t really any rules or instructions around was a trap have good welfare or not. So again, my colleagues at Landcare Research looked around a classification system for traps. So they considered an A classification as the animal’s irreversibly unconscious in less than 30 seconds. A B trap was an animal’s irreversibly unconscious in less than 3 minutes. So one’s going to be targeting the brain, and the other one might be more of a strangulation trap. And then other groups like the Department of Conservation would say, “Well, we won’t let you use traps on conservation land unless they meet the B standard”, OK? You can go out and buy traps that haven’t been tested. There aren’t any rules around stopping that. There have been a couple of traps that have been prohibited but generally not. And that’s kind of the thing. For traps, I think time until unconsciousness and death is quite easy to monitor.

When you come into toxins, which is an important part of – so any new toxin, you have to talk about animal welfare, and they all work differently. So poisons have different modes of action, and time to death is one metric only. It might be more about – well, the animal’s unconscious in 30 seconds but doesn’t die for a day, but that’s considered humane – is how do we actually measure those parameters is quite a challenging one. And there’s been some really good work done on that, but it’s certainly more around it’s more than time to death. If you’re talking about the anticoagulants, the reason they work so well is they have delayed onset of poisoning symptoms. So the animal doesn’t become bait-shy, is what we say. They eat a little bit of it, they don’t get sick. They eat a little bit more, they don’t get sick. Eventually, they eat a lethal dose, and they die. From an animal welfare point of view, they rank very poorly because of the time involved, but then you need to look at what are the physiological symptoms of poisoning. What is the behaviour of the animal? How long until they’re unconscious? Are they actually capable of feeling pain at this point?

And it’s usually with the poisons people find that a lot more difficult around those kind of things than traps. If you ask people, they’d say, “What are the most humane ways of killing animals?” Well, it’s shooting and trapping. But as I said, traps also can kill non-targets. The animal might come in at a weird angle and not get hit the way it’s supposed to be. Shooting as well, you may wound the animal. Are you using the right calibre rifle? How do you deal with an animal that you’ve wounded at 200 metres away? They all have animal welfare. But when you talk to a group and they go, “Well, how long does it take for an animal to die after eating 1080?” And you go, “Well, generally less than 24 hours.” How can that be humane? And I can understand that, but it’s more than just time to death. It’s the other symptoms and other things that they go through as well. And the Three Rs too – with that dropping drone trap, we won’t test that on real animals until we have high confidence that it actually could work.

Tom Goulter

That’s right. What’s the last thing that made you curious?

Professor James Ross

I’m reading a book (Tiny Blunders Big Disasters series, by Jarod Knott) at the moment about how small things create big events, so like that butterfly flaps its wings somewhere and creates a hurricane somewhere else. And actually the thing that made me really interested was about, we always talk about how colonisers take diseases to new countries, cholera and TB and all the rest of it. But I’m reading about how the early sailors, Columbus, actually contracted syphilis and took it back to Europe and what impact that that may have had, that one thing, that one voyage may have had on the European history and probably our history as well. But then also talking about some of the great leaders in time and who may have been quite severely impacted by syphilis and died young and what impact that had on world history. So yeah, I’m finding that really – and we were just talking before about the chauffeur with the Franz Ferdinand assassination. If he’d turned right instead of left, did that end up creating World War I and World War II? I’m finding that very interesting to read, bit morbid by the sounds of it. But those interesting little things, I suppose you could bring it back to what we’re doing. What would be that single little thing maybe we did 30 years ago that means we’re where we are now? And maybe there’s that one little moment with Predator Free that might come at some point as well that ends up being the big thing that takes us to the next level.

Tom Goulter

It’s a really interesting perspective. Thanks very much for your time, James.

Professor James Ross

Not a problem. Been great to be here.

Acknowledgements

Tom Goulter
Associate Professor Adrian Paterson
Professor James Ross
Kia Pākiki Canterbury logo, © Plains Media/Royal Society Te Apārangi (Canterbury Branch)
Images of Tom Goulter, Adrian Paterson and James Ross, © Royal Society Te Apārangi