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- Written by: Vanessa
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Photo: Hedgehogs are found right across the motu. Photo credit: Simon Gooding.
Our Pest Free Banks Peninsula programme is removing a number of pest species off Kaitōrete, including mustelids (weasels, stoats and ferrets), possums, feral cats and the hedgehog, all to help save and restore our precious ecosystems and taonga species.
It’s a funny thing. Hedgehogs have had this incredibly effective cute-washing campaign for years. Think Beatrix Potter and other children’s story’s featuring garden animals. However beloved, we need to recognise that they have real impacts on New Zealand’s special creatures, because they are above all else, very effective ground hoovers.
There is plenty of trail camera evidence of hedgehogs getting tucked into birds’ eggs, chicks and lizards; and scat has shown up all the indigestible parts of various beetles that they consume. We know that they are predators in Aotearoa, but some prey species eaten by hedgehogs can go unnoticed as they are soft-bodied (as in easily digestible and not seen in scat) and not likely to be seen on camera. So how do we know exactly what else hedgehogs are impacting on?
Photos: Kupe's grassmoth (L) and pohowera/banded dotterel (R), two species that would benefit from hedgehog removal. Credit DOC.
While there is plenty of research on hedgehogs overseas, there is much less on how hedgehogs use our landscape here in NZ. And Maryanne Walker, Lincoln University MSc student, along with her mentor Dr Alison Evans from the Christchurch City Council, are about to delve deeper into hedgehog diet preferences – especially on our ecologically important site, Kaitōrete.
They intend on using a study method first proposed by Arsalan Emami-Kyoyi on their study on NZ fur seals. This means that they are looking to collect scat samples in the field and will be using eDNA techniques to identify species against an international DNA (Barcode) database. This will mean that some samples from our native species not yet sequenced will also need to be collected and sent away to be compared against scat samples. This technique should show what the hedgehog has eaten that would otherwise be undetectable under a microscope or seen on camera. While this explanation is simplistic, it gives you an overall understanding of what they are trying to achieve.
Essentially, it is a non-invasive way to detect the diet of hedgehogs, to know what damage they may be causing and to emphasise the need for controlling them. Exciting stuff!
Let’s learn a little bit about Maryanne to start with and we’ll let her tell you about where her study will be going.
Photo: Karin (PFBP conservation dog handler), Nightshade and Maryanne at the idyllic Kaitōrete site.
Hi Maryanne, so pleased to see you tackling an important area of study! How about you tell us a little bit about yourself?
I'm originally from Nelson and that is where most of my family is still. I was lucky that my dad has a bach at the Nelson Lakes, Rotoiti, so I essentially grew up with every holiday in the bush or on the lake. I also have an aunt who’s an entomologist so always saw cool invertebrates and learned about them.
But surprisingly I actually came to Lincoln University to study a Bachelor of Agricultural Science, influenced by my mum's father who is a small-scale sheep/beef farmer. I have always loved science and being around animals so farming made sense back then. I stuck with it for a year and a half till I took an extra class – an entomology course, and I fell in love with the creepy crawlies! Looking back, I feel crazy doing 5 classes through covid but feel so fortunate to have done that as it influenced me to change my whole degree.
To be fair, invertebrates are pretty cool. What else drew you into conservation?
I completed my Bachelor of Science - in Conservation and Ecology in 2021 and completed two summer scholarships with the Pest Management and Conservation department. This included an invertebrate survey on Banks Peninsula across the Wildside, and the second was a lizard survey in the same areas. I thoroughly enjoyed these, both from being out in these amazing locations, as well as connecting with a bunch of cool landowners and Banks Peninsula Conservation Trust people and hearing their stories. But mostly because of exploring the habitats and seeing what influenced abundance hands-on instead of just reading about it.
I’ve also done lab demonstrating and field assistant work. It honestly feels like I'm just going on an adventure and having fun and I get to call it work.
I feel pretty lucky to have found conservation and now I’m in, I think I'm hooked. I am currently working towards an MSc majoring in conservation and ecology.
So how do you go from invertebrates to hedgehogs?
While considering a research topic for my master’s, Dr Cor Vink (my Lincoln University supervisor) suggested a project that he and Dr Evans had wanted a student to get their hands on. Initially, I was hesitant and the DNA/molecular side of it was a bit daunting, but in the end, I decided that this was an opportunity to up-skill in an area that isn’t common, yet will have a growing demand in, while still staying relevant to entomology.
What do you hope comes out of your research?
With my research, I hope that it can be used to open people's eyes to the damage that the 'not so cute' hedgehogs are doing. It seems to be a common theme that people always mention hedgehogs being an unmeasured threat, well now I'm hoping we can get some quantified impact to add to their conviction.
Additionally, if the methods used are successful for hedgehogs, then they have the potential to be adapted for other mammalian species to explore the complete diets of these species.
Photo: Kaptiō spider clutching egg sacs. Found on Kaitōrete in the sand dunes.
It’s such an exciting area to be in, well done so far! What would you say to other students thinking of getting into conservation research?
My advice would be to ask lots of questions, make as many contacts as you can and say yes to opportunities when they come. My career has never felt structured like I knew where I was going, and I still don't. I've been spending it following the serotonin and exploring what I found interesting. Don't worry about your friends thinking you are weird for crawling on the ground turning over logs looking for beetles (metaphorically or literally), before you know it, you'll find it hard to turn over a log without a like-minded friend by your side.
From us at Pest Free Banks Peninsula, we look forward to seeing how you get on in your study! Any information we can get to understand species like hedgehog, brings us all one step closer to understanding how to eliminate them and help our native species thrive once again.
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Many New Zealanders are not aware that hedgehogs are significant predators in our natural landscapes. Credit: Claudia Buchner
Part of the windswept Kaitōrete has been cleared of hedgehogs to protect vulnerable wildlife, in a proof of concept that’s thought to be a national first.
Canterbury based Pest Free Banks Peninsula (PFBP) is one of the country’s larger community-led, agency and iwi supported projects aiming to rid pest species off the Peninsula. Together, they have managed to achieve something remarkable.
PFBP have provided a proof of concept that hedgehogs can be removed from Kaitōrete, one of two project elimination sites for the programme. It is believed this is the first time a proof of concept has been achieved on mainland New Zealand and outside of a fenced sanctuary.
A three-step detection method was used to determine the area was free of hedgehogs. This included an array of leghold traps and trail cameras, followed by a number of sessions with the programme’s hedgehog conservation dog, Nightshade.
Nightshade consistently picks up hedgehogs in front of the programme’s trapping network, but zero detections behind it. PFBP dog handler Karin Bos explains, “Nightshade showed no sign of hedgehogs within the containment zone of 45 ha on any of the passes through the site. With nothing in the leghold lines either or showing up on cameras, we are confident there are no remaining hedgehogs in this area.”
Nightshade getting ready to grid search the containment zone (L), and with her GPS collar on (R), so her movements can be tracked. Credit PFBP.
PFBP Senior Team Lead, Tim Sjoberg agrees; “Dogs’ sense of smell is so sensitive that the possibility of the highly trained dog missing a hedgehog on multiple passes are remote”.
They have achieved this milestone through an intensive trap network, using a mixture of live capture traps and kill traps, to target a range of pest species under the elimination strategy. Other species targeted on Kaitōrete include mustelids (weasels, stoats and ferrets), possums and feral cats. With the network beginning at the western end, they have progressively moved the traps eastward, as an area is cleared. The backdoor from the west has been closed with a network of traps and an active fence system.
“We’re using a mixture of traditional methods and new technology at this site,” Sjoberg explains. “We will adapt our processes as we progress, and as new methods and products come to market.” With the information learned from this elimination work, PFBP hopes to also see the other pest species responding in the same way as hedgehogs. “We have more conservation dogs due on the ground soon, to help with our detection mahi.”
With PFBP’s partners the Department of Conservation, Christchurch City Council and Environment Canterbury all contributing to research and control on Kaitōrete, and support from Papatipu Rūnanga, community groups and landowners, this is a programme that has serious backers in the pest free movement.
In Christchurch City Council’s Regional Parks Biodiversity Team Leader Alison Evans’ experience, hedgehogs are often overlooked as pests. “They have detrimental impacts on native biodiversity in Aotearoa. They are indiscriminate predators and are responsible for population declines of many native species including lizards and invertebrates. They are also a problem for ground dwelling and nesting birds, like the pohowera/banded dotterel, by eating the eggs and young chicks.”
Environment Canterbury’s Regional Leader Biodiversity Shaun Burkett agrees. “Kaitōrete is an important habitat for many species of indigenous biodiversity and is such a unique environment. It’s encouraging to see that the PFBP adaptive approach is working.”
DOC Mahaanui Operations Manager Andy Thompson said it was exciting to see the work progressing to protect the area’s unique flora and fauna. A highlight was the way stakeholders were working together on the project.
It has been a challenge for this programme, and others across New Zealand to see hedgehogs in a light other than their cute portrayal in overseas literature. Sjoberg states, “It’s a challenge for sure, however, in our country where they have no natural predators, their populations are left uncontrolled, and they eat our native species at an alarming rate and can out compete them for food. It’s a different kind of story here.”
Kaitōrete is a unique and remarkable dryland ecosystem of international significance, home to a range of endangered plants, lizards, insects, and birds, including the katipō spider, shrubby tororaro, and pīngao. The area has great cultural significance to Ngāi Tahu and Te Wairewa and Te Taumutu rūnanga. It’s shaped like a narrow wedge set in between Te Waihora and the ocean, which makes it the ideal place to attempt to eradicate pests without a predator-proof fence as the narrow entry points can be defended from reinvasion.
Kaitōrete is home to a number of native species, some of which are only found at this site. Credit PFBP.
Next on the list is eliminating the other target pests in this challenging landscape. With PFBP onto a winning formula, there is hope that this landscape will soon allow native flora and fauna the chance to thrive once more.
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A fun blog from Jess, one of our awesome PFBP rangers.
Sometimes like a nature-driven soap opera, conservation work brings its own surprises and challenges. In the last few months, we have had a steady stream of bait station installations and servicing, and one day merges into another with little variation. Our first toxin section was relatively unchallenging terrain-wise which meant servicing the bait stations was a breeze, mostly…
There was one day that stood out. It was a crisp, sunny, late spring day, generally pleasant working conditions. Ollie and I zipped around the stations in our LUV, refilling bait stations as we went, moving between shelter belts, bush covenants and open pasture. Our day switched away from the norm when I found a young possum hanging out under a tree. It was very much alive, and I had nothing on me to swiftly dispatch it in a humane manner. So, I plucked it up by the tail. (Editor’s note – Jess is a professional, don’t try that at home). Yes, I have done this several times before. Trust me, I am an experienced possum wrangler. I then delicately manoeuvred the petulant teen-possum onto my pack to walk it back to the vehicle. It fell asleep on the walk back. Problem solved. Surely there won’t be any other distractions today…
Photo: (Left) Jess and her possum freeloader, (right) one of the bait stations she services.
Not long after the possum incident, we found a hidden bog, or more specifically it found us. I remember one of us remarking that the grass looked really green on this old farm track before naively driving forward onto it. Our LUV sank belly deep in the unexpected sludge. The miserable mire had been so well disguised! Our vehicle wasn’t going to budge so we hooked up the winch and safely got it out, only to discover there was no exit, the track on the other side disappeared into a steep impassable gully. That deceptively firm farm track led nowhere! To salvage the situation Ollie and I built an epic log bridge back across the bog so we wouldn’t get our LUV stuck AGAIN (one of the seven wonders of that farm I reckon). It was a success and almost like nothing untoward had even happened…other than for the fact both us and our vehicle were covered in mud. We were so embarrassed that we didn’t tell anyone until we got back to base. We didn’t even take photos! Everyone got a good laugh when we did fess up, so the incident was a good morale booster for the team at our expense. The lesson here; hidden bogs are a very real threat to efficient bait station maintenance schedules and should be avoided at all costs.
That was not an average day, our normal day involves slogging up hills in the heat, stopping, gasping for breath and looking out at the view again to remind yourself, YES, this hill will be WORTH IT! It can involve having frustrating battles with supplejack and bush lawyer and often losing, having to back out and find another way through. I have to be honest, installing, filling then removing bait stations is monotonous, physically challenging, and often uninspiring work. What makes up for it is the amazing views, serving the community, and the helping taonga of the Peninsula flourish.
And it is utterly splendid here...
Photo: You can't beat the Peninsula on any day!
I live for the little reminders that this is a job like no other. For example, when I am traversing difficult ground and going slowly, that’s when I notice things. The cool stuff like fungi and bugs and tiny native orchids! There are some pretty amazing things at our feet.
Photo: Stinkhorn can be found on the Peninsula, if you're lucky to stumble across it!
Thankfully in between the grueling bait station services we do get to work on other things (what I deem the fun stuff) such as setting up volunteer mustelid trap lines or installing what we have named the Bay Barrier. This barrier is a long grid of AT 220 automated traps spanning from Duvauchelle to Okains Bay. The Bay Barriers implementation signals an exciting new era of our project. This is part of the defense plan which will reduce possum reinvasion. It is my hope that everything that PFBP and the community do together these next few years will really improve biodiversity and create a sanctuary for our special species. That hope of making a difference is what keeps our team putting one foot in front of the other on those steep hill day in, day out.
Photo: It's time to rest up for another day...
