ZIP Annual Report 2018-19

Page 1

Annual Report 2018–19


ZIP field ranger Alex Edwards surveys the raging Perth River, autumn 2019 (CHAD COTTLE)


A kea at Willowbank Wildlife Reserve, Canterbury, photographed during ZIP’s trials to reduce the risk to kea from aerial predator removal operations (p. 26) (CHAD COTTLE)

Photos by Al Bramley, Becky Clements, Briar Cook, Chad Cottle, Jenny Dent, John Allen, Nigel Broadbridge (and our trail cameras!) Maps by Nic Braaksma Printed on 100% recycled stock

Contents Forewords


Devon McLean, Board Chair


Al Bramley, Chief Executive


ZIP Board


The Challenge


ZIP Team


Our Approach


The 2018–19 Work Programme Minimising Reinvasion of Predators HIGHLIGHT ONE:

Rivers as Barriers to Ship Rats

Initial Removal Projects HIGHLIGHT TWO: SIDEBAR:

Perth River Valley Predator Removal Operation

Reducing Risk to Kea

Detect and Respond Projects HIGHLIGHT THREE:

Using Lured Trail Cameras to Detect Stoats at Low Density

13 14

18 20

24 26 28


Projects to Develop and Produce New Devices


Support to Other Predator-Free Projects


Future Directions


Financial Summary


Founding Partners




Financial Statements and Auditors’ Report







Forewords He waka eke noa. We are all in this canoe together.

Devon McLean, Board Chair The mission to deliver a predator-free New Zealand is one that relies on the collective action of a diverse range of New Zealanders, including national and local Government, iwi, the commercial and philanthropic sectors, and the broader New Zealand community. During the last year, ZIP has worked alongside many of these parties to enable progress toward the predator-free goal, and has provided advice, tools and techniques in support of several large-scale predator removal projects across the country. BELOW:

ZIP Board Chair Devon McLean (JOHN ALLEN)

With the successful completion of a major predator removal trial in the Perth River valley during winter 2019, ZIP has also made great strides towards proving the ‘Remove and Protect’ model to completely, and permanently, remove predators at the landscape scale on the mainland. I’d like to take this opportunity to thank our partners – the NEXT Foundation, Department of Conservation, Morgan Foundation, Jasmine Social Investments, and Predator Free 2050 Limited – for their ongoing support. I’d also like to extend my gratitude to the ZIP Board of Directors, Charles Daugherty and David Flacks, and ZIP/DOC Senior Liaison Mike Slater, who have continued to commit their time, energy and wisdom in support of ZIP’s mission. Finally, to Al Bramley and the ZIP team – thank you, and congratulations on all that you have achieved during the past year.


Al Bramley, Chief Executive When ZIP began operations in early 2015, the goal of a predator-free New Zealand had not yet been announced, and very few people believed it was possible. Fast-forward four years, and it has been amazing to see how the momentum towards this goal has increased. With the support of our partners, including Te Rūnanga o Makaawhio, the last year has provided the opportunity to run the first large-scale test of the Remove and Protect model, at the Perth River valley field site in South Westland. While there is still much to do to replicate and refine the removal, detection and response techniques that make up this predator management approach, the opportunity to deliver the Remove and Protect model at even larger scales is almost upon us. It’s time to seriously plan for the complete removal of introduced predators from our wild places. To progress our research and development programme, ZIP relies on the support, advice and encouragement of many groups and individuals (too numerous to name here, but listed on pp. 50–51). We have achieved a lot during the last year, but we certainly have not done it alone!


ZIP Chief Executive Al Bramley (BRIAR COOK)

Finally, a word to my team: Thank you for all that you do. You continue to impress me with your drive, capability, and willingness to learn from – and adapt to – our evolving context. It’s truly a privilege to work alongside you all. Ngā mihi nui.

ZIP Board The ZIP Board met four times during 2018–19. Senior liaison with DOC is through Mike Slater (Deputy Director-General – Operations, Department of Conservation). Mike is not a Board Director, but represents the Department as a partner at Board meetings.


The Challenge The three mammalian predator species that cause the majority of ecological damage to New Zealand’s native biodiversity are possums, rats and stoats. They collectively devour an estimated 70,000 birds, chicks and eggs every night – along with a significant number of invertebrates, reptiles and amphibians. The damage possums do to native forests is also well documented: they are the major cause of the decline of many tree species, including pōhutukawa, kāmahi, kōtukutuku and rātā. The goal to completely rid New Zealand of these three predator species was set by the government in 2016, but it is a goal that New Zealanders have been gearing up to take on for some time. In fact, this year is the 60th anniversary of an impressive record of successful predator eradications from offshore islands, which began in 1959 with the removal of Norway rats from Maria Island (Ruapuke) in the Hauraki Gulf. In the intervening decades New Zealanders have successfully removed predators from over 100 islands within our waters. Today, these predator-free environments are safe havens where native species flourish.


On the New Zealand mainland, the story has been a little more complicated. Conservationists have developed and refined methods to control predators across relatively large areas using traps and the targeted use of toxins, and created fenced sanctuaries that act as small predator-free ‘islands’. But the high cost of predator fencing, and the ongoing costs associated with sustained predator control, limit the scale at which these techniques can be applied. In addition, without border defences, the persistence of introduced predators, and the speed of their population growth, prevents many native species and ecosystems from reaching their full potential.


Pīwauwau (rock wren), Perth River research area, photographed during pre-operational monitoring in March 2019 (CHAD COTTLE)

ZIP was established in February 2015 to rapidly develop the new knowledge and operationally-ready, socially acceptable methods required to completely remove possums, rats and stoats from large mainland areas and prevent their re-establishment – a model we call ‘Remove and Protect’. Achieving this will enable communities to restore native biodiversity to a level that could (in time) rival that of predator-free offshore islands, across progressively larger mainland areas. It is also expected to reduce

New Zealand’s dependence on the repeated large-scale application of toxins. And it will bring New Zealand closer to achieving predator-free status. ZIP was not established to develop new biological or genetic methods such as spreading infertility, using a virus, gene drive technology, or otherwise manipulating genes to cause possums, rats or stoats to decline to extinction. These techniques appear to offer significant potential for predator control in New Zealand, but are unlikely to be available for wide-scale deployment for many years. In contrast, the methods currently used under the Remove and Protect model are, for the most part, a matter of advancing tools and techniques that are already available and generally accepted for use by the New Zealand public.



Al Bramley


Kristin Kennedy


Duncan Kay



Nate St Hill

Jenny Dent


Matt Chisnall


Chad Cottle




Tom Agnew

Ben Blain

Robina Brock



Katie Coster


Piper Douglas


Alex Edwards


Michael Tunnicliff



Chelsea Price




He aha te mea nui o te ao? He tangata, he tangata, he tangata. What is the most important thing in the world? It is people, it is people, it is people.





Phil Bell

Nick Mulgan

Joseph Arand

John Wilks



Courtney Hamblin

Susannah Aitken



Helen Nathan


Maggie Nichols

Caroline Wallace


Madeline Bramley


Nic Braaksma



Elaine Murphy (0.1 FTE) James Russell (0.1 FTE) James Ross (0.1 FTE)


Since our last annual report, the ZIP team has continued to grow, and there have been some changes to sites and roles. To ensure that it remains a useful reference for as long as possible, the organisation chart on the previous pages is current as at 1 November 2019. This year we welcomed two new team members – GIS and Data Analyst Nic Braaksma and Predator Behaviour Team Lead Jenny Dent (initially hired as a Predator Behaviour Technician). Caroline Wallace, our Projects and Products Support, also became a permanent member of the team. We have continued to build and maintain personal connections across the ZIP team, by enabling all staff to join the work at our field sites, the predator behaviour facility (at Lincoln) and the ZIP office (in Wellington, adjacent to Zealandia Sanctuary). Twice-yearly meetings are also held to enable the whole team to connect as a group and update one another on the work programme at each site.



ZIP team members photographed at Cape Jackson Wilderness Retreat, December 2018 (CHAD COTTLE)

In August 2019 we introduced a new Employee Assistance Programme, to provide team members with confidential access to a range of services to support personal wellbeing at work and at home. Much of our work involves long distance travel to remote field sites, where the weather is frequently wet and cold, the terrain comprises steep and slippery hill and mountain slopes and challenging stream and river crossings. The Perth River research area also contains the added challenge of snow, ice and avalanche risk. During 2018–19, our staff spent approximately 2,500 days in the field. We recorded 17 work-place incidents, which included 7 injuries (none of which resulted in permanent harm). We investigated each incident, and shared what we learned across the team to minimise the risk of it happening again.

Our Approach I orea te tuatara ka patu ki waho. A problem is solved by continuing to find solutions.

ZIP’s work programme comprises five broad categories: Category of Work 1. Establish and maintain barriers to minimise reinvasion by possums, rats and stoats 2. Completely remove possums, rats and stoats from an area protected by the barrier(s) 3. Detect and respond to any predators that survive the initial removal or breach the barrier(s) 4. Develop and produce new traps, detection devices and lures 5. Provide support and advice to help enable predator free projects to achieve their goals

Our broad approach is to develop and refine the Remove and Protect model over increasingly larger field sites, until it is ready to deploy at the landscape scale. BELOW:

Resolution Bay, Queen Charlotte Sound, the home of the Bottle Rock field team (CHAD COTTLE)

We have been operating a 440 hectare field development site at Bottle Rock Peninsula, in the Queen Charlotte Sound, since ZIP’s inception in 2015. The Bottle Rock site is where we trial tools and techniques in a relatively small field area, in order to test and refine their readiness to be deployed at larger sites.


the landscape scale. The scale of the research area has also given us an opportunity to begin testing methods for the complete, permanent, removal of stoats.


Newly certified possum detection dog Pepper with her handler Michael Tunnicliff at Bottle Rock peninsula (AL BRAMLEY)

To date, we have largely focused on possums and ship rats at Bottle Rock, because their relatively small home ranges and dispersive abilities are well suited to research at a site of this scale. Stoats, in comparison, are much more mobile, with an ability to disperse many kilometres in a couple of days. Larger sites are required to test and develop methods for the complete removal and interception of stoats. Last year we began a programme of research and development work at a 12,000 hectare site in the Perth River valley, South Westland. Here, we are further developing an approach to completely remove possums, and potentially rats, from a large area that includes natural lowland to alpine ecosystems – and to prevet their re-establishment. Ultimately, the goal is to protect the natural values of the area, ideally without the ongoing use of aerial toxins at


The Perth River valley was selected as the first large-scale site to develop the Remove and Protect approach in consultation with DOC and Te Rūnanga o Makaawhio for several reasons: (i) the valley contains valued biodiversity particularly rātā and kāmahi, and as such was already subject to regular possum control – including five aerial 1080 operations since 1997; (ii) ZIP already had strong working relationships with the local DOC team, who supported earlier trials and were involved in the project from its inception; (iii) the site was deemed by Makaawhio to be a suitable location for this type of research and development within their rohe; (iv) the alpine and river boundaries made it a suitable place to test the effectiveness of these natural features as barriers to predator invasion; (v) the scale of the site (approximately 12,000 hectares) was considered to be a prudent ‘first step’ towards proving the Remove and Protect model; and (vi) the site, while remote, is relatively accessible by helicopter from the Whataroa road end. In addition to the work carried out at our field development sites, we are continuing to research and develop lures, tools and techniques at a predator behaviour research facility in Lincoln, which we opened in June 2016. This facility enables us to rapidly test potential ideas, and refine them, before trialling developments that show promise at field development sites. It also enables us to quickly terminate ideas that fail to perform as anticipated. This facility also provides Lincoln University students with useful work experience in predator related research and development (including seven who have gone on to join the ZIP team in permanent roles). RIGHT TOP:

A ZIP field ranger crosses the upper Perth River using a 3-wire bridge installed in early 2019 to enable safe, timely and cost-effective servicing of traps and detection devices (CHAD COTTLE) RIGHT BOTTOM:

Members of the ZIP field team analyse rat carcasses under ultraviolet light at the Lincoln Predator Behaviour Facility, February 2019 (BRIAR COOK)



We work closely with a range of engineering contractors (listed on p. 51) to help us design and manufacture new devices and, once the development phase is completed, to supply them.

Assessing and mitigating the potential short-term impacts of the Perth River predator removal operation on kea has been a major focus of our work during 2018–19 (refer to Highlight 1: pp. 18–19).

Because the overall positive impact of removing possums, rats and stoats from New Zealand ecosystems is well documented, ZIP generally doesn’t measure the benefits to native biodiversity of any new predator management methods. However, part of our process to develop new methods involves anticipating whether a method could have potential adverse impacts on native biodiversity, and addressing any concerns.

During 2018–19 ZIP has also had an increasing role in providing tools, technical support and advice to Predator-Free project groups around New Zealand, to help them achieve their goals. BELOW:

Predator Behaviour Technician Becky Clements sets a live-capture rat trap during trials at the Lincoln predator behaviour facility (JENNY DENT)


Field ranger Piper Douglas takes a well-earned break in the Perth River valley, winter 2019 (CHAD COTTLE)

The 2018–19 Work Programme Titiro whakamuri; kokiri whakamua. Look back and reflect, so that you can move forward.

The main knowledge/tool gaps that we planned to address in 2018–19, and the results of the work, are outlined in the following tables.

Three of these projects are highlighted in more detail in this report, and several others are described on our website (


Minimising Reinvasion of Predators Knowledge/Tool Gap



Can further refinements be made to the possum natural barrier, to improve its performance and the cost efficiency of the Remove and Protect model?

1. Undertake small scale field trial to determine whether adding an aluminium band to trees below possum leghold platforms results in more possum catches than a ‘standard’ ZIP leg hold trap set-up, by forcing possums to walk up the ramp to the trap platform in order to access the lure, rather than climbing the trunk of the tree

Surprisingly, the tubes appeared to reduce line effectiveness during a trial along the first line of the Bottle Rock virtual barrier. We suspect that the tubes may act to distract or make it harder for possums to access traps.

2. Determine whether prefeeding with stand-alone ZIP MotoLure automated lure dispensers improves the trapping effectiveness of the first line of the virtual barrier for rats at Bottle Rock

This trial ran from September 2018 to June 2019, during which time 143 rats were caught in the first line of the barrier.

Captive trials at Lincoln indicated that a 300mm wide coil, if installed correctly, is sufficient to ‘force’ 80% of possums to access the trap by climbing the ramp, rather than the tree. However, footage in the Perth has confirmed that large South Westland possums are able to cross a 300mm coil!


A possum investigates an aluminium tube installed below a leghold trap during trials at Bottle Rock peninsula (TRAIL CAMERA)

The virtual barrier we have developed to date does not yet intercept enough rats to make it cost efficient in the absence of natural barriers. Development of the virtual barrier is an ongoing challenge; we learn by trying a version and then measuring the results.


Prefeeding with egg mayonnaise was found to increase rat catch in the barrier by approximately 40%. 83 rats were caught on the prefed section of the line, and 60 were caught on the alternating control section.

Knowledge/Tool Gap



3. Determine whether trap line effectiveness improves or degrades with repeated presentation of the same trap and lure in the rat virtual barrier

We have continued to observe that rat trap line effectiveness improves with repeated presentation in the virtual barrier, indicating that it is not necessary to vary lure or trap type to improve efficacy.

4. Complete an assessment in the Perth River catchment of the effectiveness of rivers as a natural barrier to ship rats

Refer to Highlight 1 (pp. 18–19)


A ZIP ranger installs a MotoLure, found to increase rat catch in the virtual barrier by 40% when used as a prefeeding device (BECKY CLEMENTS)

In 2017–18, ZIP established that even a small braided river can act as a natural barrier to the movement of possums; however the effectiveness of large, cold, fast-flowing rivers as barriers to ship rats is uncertain. If rivers are a good barrier, then this may influence the boundaries of large mainland areas where possums and rats are targeted under a ‘Remove and Protect’ model.


Field Team Lead Courtney Hamblin surveys a rock ‘bridge’ in the headwaters of the Barlow River, Perth River valley, October 2018 (CHAD COTTLE)


Knowledge/Tool Gap



5. Undertake a field trial to determine the strength (or otherwise) of river valley headwaters (where it starts at glaciers and braids, before main flow forms) as barriers to possums and ship rats; especially in summer/low flow conditions, to inform the reinforcement network layout in those areas.

No reliable method has yet been identified to bio-mark possums. As a result, the field trial to determine the rate of possum reinvasion and the management actions required is being redesigned for implementation during summer 2019–20. In addition, pre-operational abundance indexing in the Perth River valley indicated that very few ship rats are likely to be present above 800 metres. The rat trial is unlikely to proceed due to the lack of ship rats at the trial site (the head of the Barlow River, at an elevation of approximately 1,000 metres).

The animal welfare performance of some commonly-used kill traps has not yet been confirmed.

6. Assess the animal welfare performance of the BT200 kill trap for stoats (at request of Predator Free Wellington)

Testing at Lincoln found that, for stoats, the BT200 kill trap, in a double set, double entrance ‘baffled’ wooden tunnel, meets the NAWAC (2011) specification for acceptable killing effectiveness of a Class A kill trap.

7. Assess the animal welfare performance of the DOC200 kill trap for ship rats

Testing at Lincoln found that, for ship rats, the standard DOC200 kill trap, in a single set, single entrance ‘baffled’ wooden box, met the NAWAC (2011) specification for acceptable killing effectiveness of a Class A kill trap.


A stoat investigates a BT200 trap box during animal welfare performance testing at ZIP’s predator behaviour facility in Lincoln (TRAIL CAMERA)


Knowledge/Tool Gap



Some anecdotal evidence exists that predators may cross rivers by utilising back-country swing bridges

8. Develop a gate that prevents possums, ship rats and stoats from crossing bridges, without preventing human access.

A predator gate, fitted with a rolled aluminium cap, was installed on Scone River bridge in April 2018.

9. Develop an urban ‘virtual barrier’, to help enable the Predator Free Wellington rat eradication in Miramar Peninsula

ZIP is providing advice to Predator Free Wellington and Greater Wellington Regional Council to progress development of an urban virtual barrier, and associated coast/road barriers, to prevent rats from re-establishing on Miramar Peninsula.

The gate is monitored using trail cameras; to date no predators have been observed crossing the bridge.


The predator gate installed on the Scone River bridge to prevent possums, rats and stoats crossing the river (CHAD COTTLE)

No methods currently exist to prevent predator reinvasion into urban areas (without the use of fences or geographic barriers)



Knowledge/Tool Gap In 2017, ZIP ran a trial in Remutaka Forest Park, which provided strong evidence that even relatively small, braided rivers are an effective barrier to possum movement. In 2018 we began a similar trial in the Perth River valley research area, to test whether larger rivers, reinforced with a line of traps, could also be effective barriers to the movement of ship rats.

Method The Perth River research area is bordered to the south and west by the Bettison Stream, Perth and Barlow Rivers – all of which are glacial-fed fast flowing waterways with generally rocky margins, including large boulders and rock faces. We began bio-marking rats along a 3.2km section of the true left side of the Perth River and Scone Creek in April 2018, using a line of ZIP MotoLure automated lure dispensers containing a food lure (initially peanut butter, which was later changed to mayonnaise), laced BELOW:

Mayonnaise hand-mixed with rhodamine B bio-marker, as used to mark rats during the 2018 Perth River barrier trial (CHAD COTTLE)


A DOC200 trap box fitted with a ZIP MotoLure, on the true right side of the Perth River, winter 2018 (BRIAR COOK)

with rhodamine B bio-marker. Rhodamine B, when consumed, internally stains carcasses a bright pastel orange when viewed under UV light. In rats it is also metabolised into growing whiskers for up to 70 days, where it shows up as a solid band of vivid yellow/ orange fluorescence under a fluorescence microscope. A line of kea-safe Goodnature A24 rat traps was also installed along the true left side, at 50m spacing, to ‘reinforce’ the river barrier by reducing the local rat population. In August 2018, we established a line of traps along the true right side of the Perth River and Scone Creek, directly across the river from the line of ZIP MotoLures containing the bio-marker. This trap line consisted of 155 single-set DOC200 traps (in standard wooden BELOW:

A rat whisker stained with rhodamine B bio-marker, viewed under fluorescence microscope (BRIAR COOK)


box with baffles) at 20 metre spacing, each of which was lured with egg mayonnaise, dispensed via ZIP MotoLure. Traps were checked approximately every 10 days, depending on weather and site access. All rat carcasses caught on the true right were examined on site (via field autopsy) for traces of rhodamine B staining, which would indicate that they had crossed the river. Whisker samples were collected from every caught rat for analysis under the fluorescence microscope at Lincoln University.

Results After seven months of continuous bio-marking and trapping, between August 2018 and March 2019, 169 rats had been caught on the true right of the river. Whisker samples from one rat caught in January 2019 contained clear signs of rhodamine B, indicating that at least one rat had crossed the river during the trial period. As a point of comparison, a total of 82% (32/39) of rats caught and analysed on the true left side of the river in April 2018 were found with traces of rhodamine B, meaning this proportion of the resident population (as a minimum) had been feeding from the ZIP MotoLures. This suggests that there is a reasonably high likelihood that any rats that did cross the river would contain signs of the bio-marker.

The trial ran across different seasons; including winter where the river levels are lowest but the water is at its coldest, and rat breeding and dispersal activity is likely to be minimal; but also spring/summer when the river levels rise significantly as snow and ice melts, and rat breeding and dispersal activity increases. Interestingly, we also caught 20 stoats on the true right side of the river during this trial, none of which showed signs of rhodamine B staining that would indicate they had crossed the river.

Discussion and next steps While the low rate of invasion across the river observed during this trial is encouraging, an even lower rate is likely to be required for us to be confident that this approach is a suitable option to protect large mainland sites. To that end, we are actively exploring a range of options to further ‘reinforce’ the river barriers, to reduce reinvasion to a rate of <1 rat per year, across the 19km stretch of river that surrounds this field site. This project is also described as a Finding on the ZIP website,



Initial Removal Projects Knowledge/Tool Gap



A standard aerial 1080 approach to control possums and rats over large areas does not completely remove them.

1. Test a new approach to completely remove possums and rats through the aerial application of 1080 in the Perth River valley, South Westland. We call this approach ‘1080 to Zero’.

Refer to Highlight 2 (pp. 24–26)

2. Determine the relative abundance of possums, rats and stoats within the Perth River valley prior to the proposed predator removal operation

Refer to Highlight 2 (pp. 24–26)

3. Determine the limit in elevation of ship rats and possums in the Perth River valley to inform the baiting strategy in the predator removal operation, and the extent of the detection network required to detect survivors and reinvaders

Using lured trail cameras, we recorded possum presence at 1,431 metres above sea level, rats at 1,240 metres, and stoats at 1,431 metres. The upper observation limits for possums and stoats were most likely due to the lack of cameras at higher elevations. Consequently, both phases of the predator removal operation targeted all vegetated areas (i.e. up to 1,700m above sea level).

The continued presence of predators limits the ecological outcomes of the operation and generates significant ongoing control costs.


A female ngirungiru (South Island tomtit) in the Perth River valley - one of the taonga species expected to benefit from the predator removal operation (CHAD COTTLE)

Although ship rats were recorded at 1,240 metres, a significant decline in density occurred above 800 metres.


Knowledge/Tool Gap



4. Quantify whether aversion bait is effective for kea, and devise a strategy to use it in the 1080 to Zero operation in the Perth River valley

Refer to Highlight 2 – Sidebar (pp. 26–27)

5. Quantify the effect of providing tahr carcasses as an alternative food/distraction to reduce bait consumption, and devise a strategy to use it in the 1080 to Zero operation in Perth River valley

Refer to Highlight 2 – Sidebar (pp. 26–27)

6. Assess survivorship of kea through a 1080 to Zero operation

Refer to Highlight 2 – Sidebar (pp. 26–27)

7. Assess survivorship of pīwauwau/ rock wren through a 1080 to Zero operation

With the assistance of DOC staff, we carried out two pre-operational visual surveys of pīwauwau in selected parts of the alpine zone, both within and outside the operational area. The results to date indicate that there are more than 100 pīwauwau in the research area. These surveys will be repeated in late spring 2019 as weather and snow/ice conditions allow access.


A possum caught on camera in heavy alpine snow at 1,340 metres, during winter 2018 in the Perth River valley (TRAIL CAMERA)

The potential risk to ‘non-target’ species of the 1080 to Zero approach is not well understood.


Six kea feeding on a tahr carcass deployed by ZIP in the Perth River valley, August 2018 (TRAIL CAMERA)


Knowledge/Tool Gap



8. Assess survivorship of whio through a 1080 to Zero operation

The main rivers bordering, and within, the research area were aerially surveyed before, during, and after the 1080 to Zero operation. 8 whio were recorded during pre-operational monitoring. Repeat surveys after each phase of the operation recorded 6 and 8 whio, respectively. While the sample size is small (this area is known to hold a low-density whio population), these results suggest that the predator removal operation does not appear to have had any negative impact on whio.


Male pÄŤwauwau photographed at Lord River during pre-operational monitoring in March 2019 (BRIAR COOK)


Knowledge/Tool Gap



9. Assess survivorship of tahr through a 1080 to Zero operation

In a project developed by the Game Animal Council with support from ZIP, New Zealand Deerstalker Association, Professional Hunting Guides Association, and DOC, 21 tahr were radio-collared within the Perth River research area during winter 2018.


Whio in Lower Barlow River, in June 2019 (CHAD COTTLE)

15 and 14 radio-collared tahr were present in the research area during the first and second phases of the predator removal operation, respectively. Monitoring with Sky Ranger confirmed that all of these animals survived the operation.

A small population of possums is persisting on Bottle Rock peninsula, and compromising our ability to measure effectiveness of the virtual barrier.

10. Completely remove all individual possums that are currently within the Protected area at Bottle Rock

By June 2019, very few possums were being detected within the protected area, suggesting that we had successfully removed the resident population. We then returned to managing incursion through the barrier.



A possum detected in the Perth River research area after the first phase of the predator removal operation (TRAIL CAMERA)


Knowledge/Tool Gap Current standard methods for the aerial application of 1080 enable a significant reduction in the number of possums, rats and stoats at the landscape scale on the mainland – but do not completely remove them. Consequently, in order to protect native species, predator control must be repeated on an ongoing basis, which generates significant ongoing costs (which limits the scale of areas able to be treated), and some community misgivings. With a view to helping enable a predator-free New Zealand, ZIP is attempting to develop a modified technique for the aerial application of 1080 to completely remove possums and rats from large mainland areas. Between 2016 and 2018, ZIP ran trials on Taranaki Mounga (Egmont National Park), and in the Jackson-Arawhata confluence (South Westland), the results of which suggested that the modified technique for applying 1080, known as ‘1080 to Zero’, can completely remove possums from a treatment area, and may also be capable of completely removing rats. Encouraged by these results, we worked with the Department of Conservation and Te Rūnanga o Makaawhio to initiate a 24

programme of work at a site in the Perth River valley, South Westland, to test and refine this technique. Through this work we sought to completely, and permanently, remove possums (and potentially rats) from 12,000 hectares of rugged and remote back-country. This Highlight documents the completion of the 1080 to Zero component of the predator removal operation carried out across 8,659 hectares within this site during winter 2019.

The Trial Predator abundance prior to the operation was measured using a highly sensitive network of 143 lured trail cameras (refer to Highlight 3, pp. 31–34), deployed over an average period of 45 days. Lured trail cameras were chosen after a trial conducted during winter 2018 (refer to Highlight 3, pp. 31–34) found this method to be significantly more sensitive than standard monitoring protocol. Before the first phase of the operation, 95% of cameras detected a possum; 69% detected a rat; and 45% detected a stoat. We then compared these detection rates with research from similar habitat, including from Westland. Based on that, and the extent of preferred habitat and elevation of the area,

we were able to estimate a starting population of 8,000–20,000 possums; 3,500–9,000 rats; and 20–40 stoats across the Perth River valley research area. All aspects of the 1080 to Zero technique are designed to maximise the likelihood of target animals encountering, and then consuming, the toxic bait. Unlike a standard aerial operation, the ‘1080 to Zero’ approach is carried out in two phases, with the application of toxic bait preceded by two non-toxic prefeed applications for each phase (to ‘train’ the possums and rats that the bait is a safe food source). Bait is also sown in such a way as to ensure full coverage of the treatment area (with overlapped baiting swaths, and no exclusion zones), leaving no gaps for target predators to miss out on bait. The first phase of the operation was completed in April 2019, and the second phase was completed in July. It is worth noting that during 2019 a ‘mega mast’ occurred across much of New Zealand. A mega mast is a year in which beech and rimu forests seed heavily, creating a significant natural food source for rodents. While there is only limited rimu and no beech within the

Perth River valley, it was a particularly heavy fruiting year within the treatment area for several native plant species, including miro and coprosma.

Results During the 13 weeks after the first application of toxin, 15% of cameras detected a possum; 8% detected a rat; and 5% detected a stoat. The stoat detections all occurred during the first four days, suggesting that the stoats later died from secondary poisoning. Based on these detections, our team was able to model the populations of possums, rats and stoats that remained in the treatment area after the first phase of the predator removal operation. Our estimates ranged from 13–35 possums and 5–15 rats across the research area – in other words, a likely knock-down of over 99.5% of the resident possum and rat population. This was an excellent result for an aerial 1080 operation, which we think reflects (i) the benefits of two rounds of prefeeding, (ii) the careful attention to applying a consistent coverage of bait across the entire operational area (with no exclusion zones or gaps), and (iii) the ideal weather conditions, with toxic baiting followed by 6 dry nights.


The mean weekly rate of possum, rat and stoat detections within the Perth River valley, before and after the first phase of the predator removal operation; the red dotted line represents the application of toxin on 13–14 April 2019


The intensive detection effort that followed the first phase of the operation enabled us to identify areas to target during the second phase. As a result, we were able to reduce the Phase Two treatment area by 25%, to 6,153 hectares. This is likely to have further mitigated the risks to kea and other non-target species within the research area without compromising the predator removal effort. The second phase of the operation was completed in July 2019. Since then our team has been carrying out intensive detection in the area, to determine whether the second phase succeeded in removing the small number of individual possums and rats that survived the first phase, and to confirm the impact of the operation on stoats. While early indications are promising, with three

possums, two rats, and no stoats detected as at 30 September 2019, this work will need to continue for several months to verify the success of the operation and complete any mop-up. An intensive ground-based trapping response has been initiated at the site of each detection. If the predator removal is successful, and we also successfully develop techniques to prevent predators from re-establishing, we anticipate that this work will help restore the mauri of the Perth River valley and safeguard its many natural treasures. Furthermore, if we can successfully develop an approach to completely, and permanently, remove introduced predators, then this approach could be applied to protect native species elsewhere in South Westland.


Reducing Risk to Kea Predator control using aerial 1080 has an overall beneficial impact on kea populations. In one recently published study, kea nest survival at a monitored site increased from 46.4% before the application of 1080, to 84.8% after the application of 10801. However, kea have an inquisitive nature, and some individual kea have died as a result of 1080 poisoning through direct consumption of baits. Consequently, from its inception, the research and development work programme in the Perth River valley has considered ways to reduce risk to kea from the predator removal operation. In November 2018, we ran a trial at Willowbank Wildlife Reserve which demonstrated that kea quickly learn to avoid cereal baits after being exposed to baits laced with a high concentration of a secondary repellent, anthraquinone (a behaviour known as learned food aversion).

Learned aversion relies upon consistency between baits, including how they look. Because kea, unlike humans, are able to see colours within the UV spectrum, we worked with our colleagues at the University of Auckland and Callaghan Innovation to investigate how cereal baits appear from a kea’s perspective. We found that kea are unlikely to be able to discern a visual difference between baits that contain anthraquinone and those that do not. We also ran two trials in the Perth River valley, which confirmed that the carcasses of tahr (an ungulate species originally from the Himalayas, which are abundant in the Perth River valley) are significantly more attractive to kea than cereal baits alone. The trial sites were monitored using trail cameras, which observed a high level of kea activity.

1. Kemp JR, Mosen C, Elliott GP, Hunter CM 2018. Effects of the aerial application of 1080 to control pest mammals on kea reproductive success. New Zealand Journal of Ecology 42: 158–168 26


A kea caught on camera at a tahr carcass during trials in the Perth River valley, November 2018 (TRAIL CAMERA)

Encouraged by these trials, we deployed tahr carcasses and baits containing anthraquinone at 21 sites above the alpine boundary of the operational area (i.e. above the altitudinal range of possums, rats and stoats), prior to and during each phase of the 1080 to Zero operation, to draw kea away from toxic baits and increase the likelihood of exposure to the aversion bait. The use of tahr carcasses to mitigate risks to kea was supported by the Game Animal Council, New Zealand Deerstalkers Association, and DOC. Of a total sample of 30 kea that we radio-tagged in 2018, 13 were present in the research area during the first phase of the operation, 11 of which survived. 12 kea were present during the second phase (the 11 survivors and another bird that had returned

to the area), and all 12 survived. While it is sad to lose any kea, it is important to note that all of the adult female kea in the radio-tagged sample survived. This is a positive outcome for the population, because the ground-nesting habits and extended nesting cycle of adult female kea make them particularly vulnerable to predation, and therefore most likely to benefit from the removal of predators. ZIP is working with the Kea Conservation Trust to monitor the kea nests within this area to confirm their breeding success.

ZIP’s kea risk mitigation measures are also described as Findings and associated technical reports on the ZIP website,

“I’ve shot and recovered tahr in these hills for a long time, and kea have always followed me in search of a free feed. But I have never seen as many kea in the Perth Valley area as when I was deploying tahr to deliberately feed those kea for ZIP. What they are doing to protect that valley seems to be working, and I’m stoked to be a part of it.” Gus Gordon, Glacier Country Helicopters 27

Detect and Respond Projects Knowledge/Tool Gap



How to efficiently detect a ship rat incursion at landscape scale?

1. Refine the ‘Gen One’ model, to inform the detection network layout for the Perth River valley research area

Data gathered during a trial carried out in the Jackson-Arawhata trial site during 2017–18 has been used to inform the design of a rat detection network targeting the first generation of invading rats within the Perth River valley. Using a 100m × 700m network of devices, we expect to detect a rat breeding event within 15 weeks.

The dispersal ranges of individual invading rats can be highly variable, and therefore a very dense network of devices would be required to reliably detect a single invader. However, the footprint of the first generation of offspring is expected to be much larger and, provided they can be removed quickly, could require fewer detection devices.

Model outputs will be updated on an ongoing basis as new data from the Perth River valley site and elsewhere become available.

9 weeks

15 weeks

Number of simulations

12 weeks


1 Probability of detection


Monte Carlo simulations of the probabilities of detecting a litter of ship rat pups in the first 9, 12 or 15 weeks of life (NICK MULGAN) An automated system for reporting the detection of rats. Rats are highly reproductive and can quickly establish a population. It’s critical to know as soon as possible when a rat is present in an otherwise ‘rat free’ area, so that a prompt response can be initiated. It is also important to be able to quickly retrieve caught animals, in good condition, to enable analysis of age, sex and breeding status.


2. Investigate the use of a tunnel-architecture trap, with automatic reporting, to quickly and reliably detect a rat incursion at landscape scale.

A new tunnel architecture trap (refer to p. 35, 36 and 38) is currently undergoing field testing at Bottle Rock, Lincoln, and the Perth River valley. The trap is designed to be compatible with both the ZIP MotoLure automated lure dispenser and the ZIP OutPost remote reporting system.

Knowledge/Tool Gap



Can we use wildlife cameras coupled with ZIP MotoLures to better detect stoats?

3. Initiate a trial in the Perth River valley to determine whether wildlife cameras coupled with ZIP MotoLures can be used to provide more sensitive and timely detection of stoats

Refer to Highlight 3 (pp. 31–34)

The ability to reliably bio-mark possums and stoats using a single, long-lasting, bio-marker would enhance our ability to efficiently measure the effectiveness of management activities (e.g. by tracking movement of animals through a ‘barrier’ system).

4. Develop reliable bio-marking of possums and stoats

Trials at Lincoln during 2017–18 indicated that egg mayonnaise laced with rhodamine B bio-marker is highly palatable to both possums and stoats, and can be reliably delivered via the ZIP MotoLure.

Can we improve our detection toolset for confirming the presence/ absence of possums and rats within our field sites?

5. Continue to develop predator detection dog capability within the ZIP team

The best practice deployment of tracking tunnels is not sensitive enough to detect the presence of all stoats. In addition, stoats are so mobile that timely information is needed to initiate a targeted response.


Trail cameras paired with ZIP MotoLures were found to be a highly sensitive method to detect possums, rats and stoats (TRAIL CAMERA)

Unfortunately, to date, we have been unable to reliably bio-mark possums using this method. Trials are ongoing to assess whether this method has potential as a means for bio-marking stoats.

Pepper, a possum detection dog, and Baxter, a rat detection dog, are both now fully certified. Ongoing training and handling of these dogs is the responsibility of two members of the ZIP field team, Chelsea Price and Michael Tunnicliff.


Knowledge/Tool Gap



6. Release radio-collared possums at Bottle Rock field site, in order to determine how long it takes for them to be caught in the lean detection system

This trial was put on hold while the team focused on re-eradicating possums from Bottle Rock. However, the success of the re-eradication suggests that the lean detection system on the peninsula is working well, so this trial may no longer be required.


Rat detection dog handler Chelsea Price and her dog Baxter prepare to cross a swing bridge fitted with a predator gate in the Perth River valley (CHAD COTTLE)

It is unknown how long it takes for a possum to be caught in a lean network of traps (i.e. the ‘lean detection system’). The longer a possum is ‘free to roam’ within a protected area, the greater the risk that it will encounter another possum, then stop roaming (making it harder to detect) and breed.


Surviving or invading possums at Perth River valley are likely to be fitted with radio collars after they are caught, to see how and where lonely possums roam in that landscape.


A stoat caught on camera during pre-operational indexing in the Perth River valley, April 2018 (TRAIL CAMERA)


Knowledge/Tool Gap Detecting stoats when they are in low numbers is challenging. This Highlight describes the interim results of a project with the primary objective to determine the stoat density in the Perth River valley, using trail cameras paired with ZIP MotoLures. A secondary objective was to determine the level of interaction of stoats with the lure dispenser, to help us to understand the potential of this device as part of an invasion response strategy.

The standard method to determine the relative abundance of stoats is to place tracking tunnels along survey lines throughout the area of interest, bait the tunnels with a piece of rabbit meat bait for a period of three fine days, and then check the tracking card/paper inside the tunnels to see whether any stoat footprints have been recorded2.

2. National Pest Control Agencies 2015. A1 possum population monitoring using the trap-catch, waxtag and chewcard methods.


However, the standard method generally does not detect stoats to the desired degree of sensitivity when they are at low density3. That’s because the three-day period of monitoring is not long enough to detect stoats; in part because animals are usually reluctant to interact with a newly installed device, and only a portion of their range will include the tracking tunnel network, making encounter less than certain. Longer periods are generally not feasible because it is too expensive to manually refresh the bait, and because a longer period increases the risk of damage to the tracking paper as a result of wet weather. The lack of sensitivity when stoats are at low density is a significant limitation that can compromise the success of programmes designed to protect native species that are very susceptible to stoat predation (e.g. kiwi chicks). It is also a limitation where the goal of the operation is the complete removal of stoats, as in the case of the Remove and Protect model that we are seeking to develop. In these situations, a more sensitive method is needed to detect stoats and assess the effectiveness of an operation and/or detect incursion. Using cameras is generally considered to be a more sensitive method because cameras can be deployed for longer periods without the operational requirement to frequently change the bait (when used un-lured), the memory cards are less vulnerable to the adverse effects of wet weather, and stoats do not have to interact with the camera in order to be detected.


Egg mayonnaise delivered from a ZIP MotoLure (automated lure dispenser) (BECKY CLEMENTS)

Method ZIP has developed an automated lure dispenser – the ZIP MotoLure. 95 MotoLures were paired with Browning Dark Ops (6HD-940) trail cameras on a grid of approximately 700 × 500 metres (or one every 35 hectares) throughout the Perth River valley research area, at altitudes ranging from 250 to 1,240 metres above sea level. This density of network was to ensure there was at least 1 lured camera within a stoat home range (which can range from 30–800 hectares4). In total, the array of dispensers and cameras covered approximately 3,700 hectares of rātā-kāmahi forest and sub-alpine vegetation. The ZIP MotoLure can deliver a small amount of semi-liquid lure at a desired volume and frequency for up to one year before requiring servicing. Egg mayonnaise has

3. Smith DH, Weston KA 2017. Capturing the cryptic: a comparison of detection methods for stoats (Mustela erminea) in alpine habitats. Wildlife Research 44(5): 418-426 4. King CM ed. 2005. The handbook of New Zealand mammals. 2nd edition. Melbourne, Oxford University Press. 610 pp.


long been known to be palatable to stoats5. For this project we used “Best Foods” brand mayonnaise; we confirmed its palatability through pen trials at our Lincoln predator behaviour facility. Each MotoLure delivered 0.15ml of egg mayonnaise, three times a day, for a minimum period of three weeks during June and July 2018.

In comparison, when we used the standard indexing protocol over the same area two months earlier, only 1.7% of 60 tracking tunnels (i.e. 1 tunnel) detected a single stoat.


38% of the cameras that detected stoats (i.e. 15 cameras) also recorded stoats interacting with a lure dispenser on at least one occasion. Stoats were recorded as interacting with a MotoLure on multiple days at 10% of the cameras (i.e. 4 cameras). A stoat was determined to have “interacted” with the dispenser if the images showed it clearly eating the lure, or investigating the MotoLure, or changing its behaviour by moving towards the MotoLure rather than past it. Owing to the constraints of the camera settings, we expect that the actual number of interactions is likely to be higher than the level of interaction recorded.

Of the 95 cameras, 41% (i.e. 39 cameras) detected stoats on at least one occasion, of which 46% (i.e. 18 cameras) detected stoats on multiple days.

On the basis of these detections, we were then able to estimate stoat abundance within the research area through an occupancy modelling approach.

The cameras in this project were programmed to take a burst of three images whenever an animal was detected, with each image 0.3 seconds apart, and a 5 second delay between each burst. These settings were designed to maximise the length of time that the camera could run for before the SD memory card was full.

5. King CM, Powell RA 2007. The natural history of weasels and stoats: ecology, behavior and management. 2nd edition. New York, Oxford University Press. 446 pp.



A stoat feeds from a ZIP MotoLure in the Perth River valley detection network (TRAIL CAMERA)

We used the abundance-induced heterogeneity (RN) model, which assumes that animal abundance and detection probability are linked. The model can be informed by adding covariates for each camera trap site (in this case, altitude) and subsequently estimates the average number of animals at the camera site level, which can then be averaged for cameras across the study area. The RN model also estimates a probability of detection for an animal across a site given their history of detection at each camera. The model determined that both stoat abundance and detection probability varied depending on the altitude of different camera trap sites, and using this information, estimated a total of 31 stoats across the camera network, with a range of 21–46.

Discussion This project confirmed that a comprehensive network of paired lure dispensers and cameras, deployed for three weeks, will detect approximately 30 times more stoats than a standard tracking tunnel method deployed over three days. It cost approximately $17,000 of field team time to install the network of 95 paired lure dispensers and cameras, and to subsequently remove them. This equates to approximately $5/ha over the course of the project (or $60/ha annually if run continuously as a detection system).


Each image recorded by the cameras was reviewed by a team member, at a rate of c.2,500 images per hour. Less than 1% of the images were of the target – i.e. stoats! The majority of the other images were of possums (59%) and rats (20%), or were unable to be identified (17%). Clearly the number of non-targets can significantly influence the time required for data processing. Other related expenses included establishing the survey lines the devices are located on, helicopter transport (approximately 5 hours), and the capital cost of the MotoLures and cameras (i.e. approximately $125 and $220 excl. GST each, respectively). Despite the high labour costs, the vastly increased sensitivity of detection (across all target species) warranted deployment of a full network of 143 lured cameras across the Perth River site, for research and development purposes (i.e. survivor detection after the predator removal operation). In order to make camera-based detection an efficient approach for protecting large mainland areas, ZIP is exploring the potential of artificial intelligence and remote reporting to ‘weed out’ non-target detections and remove the requirement for regular manual servicing of cameras. This project is also described as a Finding on the ZIP website,

Projects to Develop and Produce New Devices Knowledge/Tool Gap



1. Develop a highly effective ‘tunnel’ trap for rats and stoats, and productionise it through tooling to final manufacture.

Plastic tooling of the first version of the tunnel trap, currently known as the ‘ZIPinn’, was completed in China during June 2019. 350 units are currently being deployed in the Perth River valley, and another 125 at Bottle Rock.


Field ranger Jono Dobbs prepares to deploy our prototype tunnel-architecture rat and stoat trap at the Perth River valley field site, winter 2019 (CHAD COTTLE) Can we improve the effectiveness of devices used to catch and detect ship rats and stoats? ‘Tunnel’ architecture traps have been found to be 1.5 times more effective at trapping ship rats than standard single-entry trap boxes. Testing of both the prototype ‘ZIP200’ tunnel trap, and the DOC200 trap in a single-entry box, revealed that some ship rats are able to trigger these devices without being caught.

The trap comprises a plastic tunnel with spring-loaded doors at each end, which close instantly when a rat or stoat activates one of two treadles in the centre of the tunnel. Caught animals are then automatically euthanised using carbon dioxide, a standard humane laboratory technique. The trap is designed to be compatible with both ZIP’s MotoLure automated lure dispenser and OutPost remote reporting system.


Knowledge/Tool Gap



In the ‘Remove and Protect’ model, it is important that all animals that engage the trap are caught, and then able to be quickly retrieved, in good condition, to enable analysis of age, sex and breeding status.

2. Field test prototypes of a new tunnel trap (the ‘ZIPinn’) to confirm its performance, relative to the TUN200/DOC200, and its effectiveness in catching and killing rats

Behavioural trials at Lincoln found that ship rats interacted significantly more quickly with the ZIPinn than with the TUN200 trap, and that each trigger event resulted in a successful catch (i.e. no rats escaped from the prototype ‘tunnel trap’).

We do not have a proven ‘social’ lure for rats.

3. Continue to investigate the effectiveness of a range of audio lures

These trials are currently on hold due to higher priority work underway at Lincoln, along with the ongoing challenges associated with communicating with rats in the ultrasonic spectrum.

4. Investigate the ability of an electric grid to deter possums, rats and stoats

Trials at Lincoln during 2017–18 found that the electric grid was likely to be an effective deterrent for possums and stoats, but would need to be re-designed in order to be effective against ship rats.

Treadle weight testing is continuing at Lincoln and Bottle Rock to optimise rat catch, while minimising false spring-offs.

This may be important in rat-free areas where there is abundant food but rats are lonely.

There are no tools to prevent possums, rats and stoats from passing through openings in fence barriers. In agricultural or urban environments, predator fences are likely to have gaps (e.g. to enable vehicles to pass through).


A ship rat attempts to climb over a prototype low-height fence capped with a length of 90mm diameter HDPE pipe during trials at the Lincoln predator behaviour facility (BECKY CLEMENTS)


Development is currently on hold to enable progress with higher priority work.

Knowledge/Tool Gap



Predator fencing is typically custom-designed and built, making it an expensive option for large sites.

5. Productionise the low height predator fence for possums, rats and stoats to support other projects

Trials at Lincoln during 2017–18 found that a 1.1 metre high predator fence (with standard capping and mesh) contained 22/23 stoats, 20/21 possums and 20/20 ship rats.

A productionised low height predator fence could make this tool affordable and suitable for use in a wider range of places (e.g. around farms and residential areas, where standard predator fences might not be desirable).

To further reduce the cost of predator fencing, an alternative design using lower-cost capping materials was constructed in mid-April 2019, and is currently undergoing testing at ZIP’s Lincoln facility. The design consists of a 1.1 metre high fence, capped with a 160mm diameter plastic pipe. To date only two possums have attempted to cross the fence.

We need a remote system that can transmit data over long distances (to enable timely response to incursions). Our ultra-high frequency ‘daisy chain’ automated reporting system works well within our barrier lines, where devices are typically spaced less than 20m apart. However, we also need a system that can transmit results where the network of devices to detect and respond to incursions is separated by longer distances.

6. Assist the development of a low height rat-specific fence and solutions for road and coastal ends, to support the Predator Free Miramar Peninsula project (within Predator Free Wellington)

An 800mm high fence, constructed with 12mm mesh and capped with a 110mm diameter HDPE pipe, was found to prevent 15/16 ship rats, and 3/3 Norway rats, from crossing during trials at Lincoln.

7. Continue to develop a hybrid system for remote data transmission, using a long-range, low powered radio (LoRa) backbone, our ‘daisy chain’ technique to get into hard to reach terrain, and the Iridium satellite network.

Ongoing improvements are being made to the LoRa system, including optimising the timing of the satellite communications component and improving the antenna design to increase the range of automated reporting nodes (currently estimated at over 200 metres in unfavourable terrain).

The initial design used a 90mm diameter pipe cap, but his was increased to 110mm after 2/15 ship rats were able to cross the fence.

The new node design is now being manufactured and productionised for deployment in the Perth River valley, along with several partner projects.


Knowledge/Tool Gap



While trail cameras are known to be a highly effective method for detecting survivors and incursions, the high service costs associated with these devices limits the scale at which they can be used

8. Develop a low-powered field-ready artificially intelligent (A.I.) camera for sensitive, efficient, detection of stoats (and in time, possums)

With the support of Predator Free 2050 Limited, we have initiated a project to develop a low-powered field-ready A.I. camera. Early testing of machine learning tools for the image recognition component of A.I. is underway.

To enable landscape-scale deployment of the possum ‘lean detection’ and ‘virtual barrier’ systems, a highly effective, production-ready leghold trap platform is required.

9. Refine and productionise possum leghold trap platform

The ZIP PosStop possum trap platform is now available for purchase, along with optional ZIP OutPost automated reporting functionality.


Our automated reporting rat and stoat trap, currently known as the ‘ZIPinn’, fitted with a ZIP OutPost trap node (left) and ZIP MotoLure (right), undergoing field testing in the Perth River valley (CHAD COTTLE)


A ranger installs the ZIP PosStop leghold trap platform at Bottle Rock peninsula (CHAD COTTLE)


Knowledge/Tool Gap



Non-target species may be at risk from leghold traps used in the Perth River valley possum ‘lean detection’ system.

10. Develop and field-test a leghold trap with daytime lockout functionality, to minimise the risks to non-target species that are active during the day

The trap is currently undergoing field testing at the Taranaki Taku Tūranga project site. Not unexpectedly, given the nature of research and development, some bugs were identified, and testing is ongoing to confirm whether these have been addressed by subsequent software improvements. The lockout mechanism works to ‘close’ traps, rendering them safe during the daytime. However, kea in the Perth River valley have learnt how to disable the trap by interfering with the trap chain or jaws. Consequently, we now intend to use cameras as our primary detection tool for possums in kea habitat, and carry out targeted trapping using the ZIP OutPost reporting system in response to any camera detections.

Thermal camera survey and hunting capability of predators, and other pests, is limited.

11. Investigate the pathway to rebuild high resolution thermal camera survey and hunting capability within New Zealand, to assist the rural and remote eradication of possums, goats, pigs, wallabies and feral cats (to support both ZIP’s work and the work of several partner projects)

ZIP is currently discussing the need and project parameters with potential collaborators, team members, technical suppliers and funders. Leveraging connections made at a US trade expo during autumn 2019, a cooled thermal camera was hired from a French company, Sofradir, for comparative detection trials at Bottle Rock. The cooled thermal camera proved to be 2–3 times better at identifying thermal signatures of animals than the ‘uncooled’ technology currently in use in New Zealand and Australia.


An uncooled thermal camera undergoing evaluation at Bottle Rock Peninsula for aerial hunting and survey of invasive species (CHAD COTTLE)


Support to Other Predator-Free Projects Project

Project description

Support/ advice provided by ZIP

Taranaki Taku Tūranga – Towards a Predator-Free Taranaki***

Taranaki aims to be the first predator-free region in the country, under the Taranaki Taku Tūranga project led by the Taranaki Regional Council.

ZIP supported DOC and Taranaki Regional Council to plan and review a ‘1080 to Zero’ possum removal operation, as part of a project to restore the Kaitake Range.

It is understood to be the largest predator-free project of its kind in the world, removing predators from rural, urban and conservation land, and then preventing their re-establishment.

Predator Free Hawke’s Bay*

The Predator Free Hawke’s Bay Project builds on the success of the Cape to City and Poutiri Ao ō Tane projects. The first phase of this project, led by the Hawke’s Bay Regional Council, will focus on removing possums, and controlling feral cats and mustelids, across the 15,000 hectare Mahia Peninsula.

ZIP has also been grateful for the opportunity to work alongside the Taranaki Taku Tūranga team to develop and deploy a ‘virtual barrier’ of leghold traps, with ZIP OutPost automated reporting functionality, and daytime lockout, to prevent possums re-populating the Kaitake Range following the possum removal operation.

ZIP has provided advice, support and tools to assist the Hawke’s Bay Regional Council to plan, implement and review the possum removal phase of the Mahia Peninsula restoration project.

The project aims to reduce the costs of farmland predator control by at least 50 percent, enabling redeployment of resources and ultimately a shift in focus from suppression to eradication across rural landscapes.

Maukahuka Pest Free Auckland Island**

Following the successful eradication of mice from Antipodes Island, DOC, Ngai Tahu and NEXT Foundation are investigating the feasibility of eradicating pigs, feral cats and mice from Auckland Island (Maukahuka) in the New Zealand subantarctic island region. Maukahuka is the last island in the New Zealand subantarctic region that has predators on it.


ZIP has provided advice to the Maukahuka (Auckland Island) eradication project team to help build the business case for eradication; investigate the utility of ZIP tools (including the MotoLure and OutPost automated reporting system); and explore the potential of thermal aerial hunting to remove pigs and feral cats.


Project description

Support/ advice provided by ZIP

Te Manahuna Aoraki Project**

Te Manahuna Aoraki is a large-scale conservation project focused on restoring the iconic natural landscapes and threatened species of the upper Mackenzie Basin and Aoraki National Park.

ZIP assisted the project team to install the mustelid control components of the restoration project, and is working alongside the team to explore the feasibility of a robust predator fence for use at high altitude.

Launched in November 2018, the project will enhance biodiversity across 310,000 hectares of stunning New Zealand landscapes, including braided river systems, alpine habitats and Aoraki/ Mount Cook National Park.


A fencing contractor installs a section of predator fence at a site in Canterbury, to assess its suitability for use at high altitude (NIGEL BROADBRIDGE) Predator Free Wellington***

Predator Free Wellington is a charitable organisation supported by Wellington City Council, Greater Wellington Regional Council, NEXT Foundation and Predator Free 2050 Ltd, with the vision of enabling Wellington to become New Zealand’s first predator free city – and the world’s first predator-free capital.

ZIP is providing advice to Predator Free Wellington and Greater Wellington Regional Council to progress development of barriers (both ‘virtual’ and physical) to prevent rats from invading Miramar Peninsula. ZIP has also assisted with testing of traps and lures, and provided other advice to the operational team as the eradication progresses.



Project description

Support/ advice provided by ZIP

The Predator Free Dunedin project draws on the combined effort of 20 conservation related agencies and groups, building on community restoration efforts over more than ten years and recent TB predator control investments by OSPRI.

ZIP will soon test a fence design developed by the Predator Free Dunedin project group to prevent possums re-establishing on the Otago Peninsula. The fence design is based on a standard stock fence fitted with chicken mesh and three hotwires. Some anecdotal success has been reported, which our testing will seek to verify.


The site of the urban ‘virtual barrier’ designed by ZIP in support of Predator Free Wellington’s efforts to protect Miramar Peninsula against reinvasion by rats (BRIAR COOK) Predator Free Dunedin*

The project aims to remove possums from 9,000 hectare Otago Peninsula and suppress possums and mustelids across landscapes north of Dunedin bordered by State Highway 1, to create a halo around Orokonui Ecosanctuary.



Project description

Support/ advice provided by ZIP

Predator Free 2050 Limited is a Crown-owned, charitable company established to help deliver the New Zealand government’s ambitious goal of eradicating possums, stoats and rats by 2050.

ZIP provides support and technical advice to assist candidate projects to prepare project plans for Predator Free 2050 Limited.


A possum-specific fence designed by the Predator Free Dunedin project group, which will be tested at ZIP’s predator behaviour facility in Lincoln. (AL BRAMLEY)

Predator Free 2050 Limited

Predator Free 2050 Limited provides co-funding to enable predator removal projects at landscape scale and the breakthrough science needed to underpin them.

* Supported by Predator Free 2050 Limited ** Supported by NEXT Foundation *** Supported by both Predator Free 2050 Limited and NEXT Foundation

At the request of Predator Free 2050 Limited, ZIP also provides ongoing general support and advice to help enable funded projects to achieve their goals. We expect this demand for advice and support to grow as more predator-free projects get underway.

We have also continued to publish Findings, technical reports, literature reviews and updates on the ZIP website,, to make our learning and progress easily accessible to others.



A ZIP ranger stands at the confluence of the Perth and Barlow Rivers (CHAD COTTLE)

Future Directions WhÄ ia te iti kahurangi ki te tĹŤohu koe me he maunga teitei. Seek the treasure you value most dearly; if you bow your head, let it be to a lofty mountain.

44 F U T U R E DI R E C T I O NS

The next two years promise to be another challenging and stimulating period for the ZIP team, in which we expect to continue to make progress toward enabling the complete and permanent removal of possums, rats and stoats from large mainland areas for the long term, sustainable protection of native biodiversity. Now that we have undertaken the predator removal operation in the Perth River valley, we will focus on developing and refining tools and techniques to detect and respond to surviving and/or invading predators in back-country, largely forested areas, in order to prevent them from re-establishing there. The response options will likely comprise the intensive use of traps and/or toxins, at small scale. We will also need to be vigilant for fallen trees that could provide natural bridges into the protected area and remove such trees as soon as they are detected. In addition to continuing our work to protect and restore the Perth River valley, we are investigating options to replicate and refine the approach applied there at an adjacent site (yet to be confirmed) in the Whataroa River catchment. Doing so would also enable us to learn how well the approach works during a season where the vegetation is not expected to fruit heavily (providing abundant natural food for possums and rats) as it did last season. We may also take the opportunity to test how well a single toxin treatment (after two pre-feeds) can remove predators from a treatment area. We expect to also increase our investment in two projects to rapidly research and develop exciting new predator management tools/ techniques. The first project is to develop a low-power, remote-reporting camera with on-board artificial intelligence, to detect possums, rats and stoats in back-country forests (as briefly described on p. 38). This tool will improve our ability to sensitively detect predators and the timeliness of our response, while significantly reducing the overall cost of doing so. We expect this device could also be useful for other conservation management purposes.

The second project will investigate the feasibility of rebuilding and improving New Zealand’s capacity to use helicopter-based thermal imagery to assist in the removal of the final animal pests from a treatment area and to survey the treatment area to confirm predator/pest freedom. This tool (as briefly outlined on p. 39) could be used to manage an expanded suite of predators including goats, pigs, wallabies and feral cats. In part, this project is necessary owing to the unexpected passing of Grant Halverson – a remarkable pioneer in this field of conservation management. We have completed development of the ZIP PosStop (possum leghold trap system) and the ZIP MotoLure (the automated lure dispenser), and started to supply these products to the managers of predator free projects throughout New Zealand. We expect to complete development of the ZIP OutPost remote reporting system (in part, through field testing with predator free projects), so that it can be made available to others as well. The supply of ZIP-developed products is a new addition to our range of activities – and something that brings us a lot of satisfaction, because these operationally-ready tools help other people to achieve predator freedom to restore native biodiversity on the mainland. The expressions of interest in ZIP-developed products and support that we have received from predator-free managers indicates to us that this coming year will be a busy one for our product supply team.


Financial Summary Founding Partners



Kea spotted in the Perth River valley in May 2019, after the first phase of the predator removal operation (CHAD COTTLE)


Financial Statements and Auditors’ Report ZIP’s 2018–19 financial statements were prepared by The Business Advisory Group (TBAG) and audited by PWC. We are pleased that a favourable audit was received. A full set of statements is available at The chart below provides a summary of expenditure (excluding depreciation) in 2018–19. Minimise Reinvasion of Predators Empower the ZIP Team $648k

12% Support Others




13% $1,804k


Completely Remove Predators


22% $522k

Develop/Produce New Devices

10% Detect/Respond to Reinvasion 47

Glossary 1080 to Zero

modified approach to aerially applying 1080, developed by ZIP with advice A from DOC, OSPRI and Manaaki Whenua – Landcare Research, to completely remove introduced predators. The approach differs from a ‘standard’ 1080 operation in that it is carried out in two phases, the application of toxic bait is preceded by two non-toxic ‘prefeed’ applications, the toxic sowing rate during the first phase is 4kg/ha (as opposed to 2kg/ha) and bait is sown in such a way as to ensure full coverage of the treatment area (no exclusion zones, and overlapping baiting swaths).


self-resetting multi-species kill trap targeting rats and stoats, developed A by Goodnature.

Complete removal

he removal from an area of all individuals in a species, or enough individuals T that the remaining population is no longer viable (i.e. functionally extinct).

Gen One

An approach ZIP is developing to design a lean system to detect an emerging population of rats in an otherwise rat-free area, by determining the spatial ‘footprint’ of a litter of juvenile ship rats and then targeting their complete removal.

Lean detection

sparse network of devices to detect invading possums, rats or stoats in a A protected area and enable a rapid response before a population can establish.


oRa is radio technology that has been developed to enable low data rate L communications to be made over long distances using very low power levels.


SPRI is a partnership between primary industries and the government to O manage two national programmes – NAIT and TBfree. NAIT provides the national animal identification and traceability system and TBfree aims to eradicate bovine TB from New Zealand by 2055.

Protected area

n area under protection, which has been cleared of possums, rats and A stoats. The protected area is behind a barrier – either natural or virtual – and contains a ‘lean’ detection network to detect and enable a rapid response to the presence of invaders.


non-toxic bio-marker that fluoresces bright green under a UV light, and A temporarily stains the digestive tract of animals that have ingested it, along with any areas of skin, fur or feathers that have contacted the marker.

Remove and Protect The ZIP operating model whereby possums, rats and stoats are completely

removed from large mainland areas, and prevented from re-establishing. Rhodamine B

dye, sometimes used as a bio-marker. Rhodamine B fluoresces pastel A orange under a UV light, and temporarily stains the fur and digestive tract of animals that have ingested it. In addition, it is detectable as a vivid yellow/ orange glowing ‘band’ in the growing whiskers of rats, when observed under a fluorescence microscope.

Snap trap

wooden, metal, or plastic trap with a powerful snap hinge intended to kill A rodents instantly on contact. Snap traps are typically used with bait to lure the rodent to the trap.

48 G L O SS A RY

Trail camera

camera used to capture and store photographs in remote settings. Trail A cameras are commonly used by hunters, researchers and conservation managers to covertly observe animals in the wild.


prototype rat and stoat trap box developed by ZIP, which contained A two side-by-side DOC200 kill traps in a wooden ‘run-through tunnel’ box (superceded by the ZIPinn tunnel trap).

Virtual barrier

n intensive network of trap lines installed to prevent invasion by possums, rats A and/or stoats into an area under protection.

ZIP MotoLure

novel automated lure dispenser developed by ZIP that is capable of dispensing A a fresh food-based liquid or semi-liquid lure in the field every night for up to a year.

ZIP OutPost

n automated reporting system developed by ZIP to enable timely transfer of A data from the field. The OutPost system is compatible with ZIP’s suite of devices, and can reduce the labour costs associated with monitoring a network of traps by over 90%.

The OutPost system includes LoRa (low-powered radio)-enabled automated reporting trap nodes; satellite boxes to receive and transmit data; and a webserver to notify the status of devices and enable users to interface with the system. ZIP PosStop

A PCR No. 1 Leg-hold trap presented in a raised platform developed by ZIP. Each component of this device has been carefully designed and extensively tested to maximise the effectiveness and efficiency of possum trapping operations (catching over 20% more possums than a ‘standard’ raised set), while reducing potential risks to non-target species.


trap developed by ZIP for rats and stoats, which consists of a tunnel with a A spring-loaded door at each end. When either one of two treadle plates within the centre of the tunnel is activated by a rat or stoat, both doors close. The caught animal is then automatically euthanised using carbon dioxide gas, a standard humane laboratory technique. Currently undergoing testing at ZIP’s research sites. (The ZIPinn trap is likely to be given a different name when ZIP makes it available for purchase.)


Science and Technical Ranger Briar Cook collects whisker samples from a rat caught during ZIP's river barrier trials in the Perth River valley, May 2018 (CHAD COTTLE)


Acknowledgements Ehara taku toa i te toa takitahi, engari he toa takitini My success is not mine alone – it is the success of a collective.

ZIP is grateful for the ongoing support and advice of our founding partners and funders (refer to p. 46), along with: Cacophony Project Callaghan Innovation Federated Farmers Federated Mountain Clubs Forest and Bird Game Animal Council Greater Wellington Regional Council Hawkes Bay Regional Council Kea Conservation Trust Lincoln University Manaaki Whenua – Landcare Research Maukahuka Pest Free Auckland Island New Zealand Deerstalkers Association OSPRI Predator Free Dunedin Predator Free Hawke’s Bay Predator Free New Zealand Trust Predator Free Wellington Project Janszoon Taranaki Mounga Project ABOVE:

Department of Conservation Engineering Manager Jono Calder surveys the site of a 3-wire bridge across the Perth River to enable safe, timely and cost-effective servicing of traps and detection devices (AL BRAMLEY)

Taranaki Regional Council Taranaki Taku Tūranga Tararua Tramping Club Te Manahuna Aoraki Project Te Rūnanga o Makaawhio Te Rūnanga o Ngai Tahu University of Auckland West Coast District Health Board West Coast Regional Council West Coast Tai Poutini Conservation Board Westland District Council ZEALANDIA


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