A trial on Te Pākeka/Maud Island for reducing aerial baiting sow-rates for the eradication of house mice

Oyston, Emmanuel; Horn, Stephen; Murphy, Elaine

doi:10.20417/nzjecol.47.3499

Cited by 5 publications

(11 citation statements)

References 18 publications

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“…Increasingly, larger or more complex eradications are being proposed that will require adaptation of best practice (e.g. Horn et al 2022;Livingstone et al 2022;Oyston et al 2022). We recognize the interaction of pests, food resources and the environment mean there is likely no 'one size fits all' solution for these complex projects.…”

Section: Discussionmentioning

confidence: 99%

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Population trends of house mice during tussock mast seeding on Auckland Island

Sagar¹,

Cox²,

Horn³

et al. 2022

NZJE

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House mice (Mus musculus) are an invasive species on Auckland Island in the New Zealand subantarctic and planning for their eradication is underway. Mast seeding events cause rodent populations to irrupt, though little is known about this phenomenon in snow tussock grass (Chionochloa spp.) systems on Southern Ocean islands. The aim of this study was to understand population fluctuations of mouse abundance on Auckland Island for the 2 years following a mast event, and with which tools to monitor abundance, to inform planning of bait application for eradication. Mouse populations were studied using kill and live trapping at two sites on Auckland Island, and mouse density was estimated using spatially explicit capture-recapture models. Mouse population density was highest during summer mast seeding of Chionochloa antarctica and then declined the following winter and subsequently remained low for the following year. Breeding remained seasonal, with a pulse in early summer and a very low level continuing through winter in both years, regardless of mast conditions. These results are similar to those from other cool temperate Southern Ocean islands where seasonal resource availability appears to drive breeding. Throughout the study the capture probability of mice was generally higher when population density was lower, which highlights that conclusions about population trends could be misleading if abundance indices are not calibrated to measures of population density. Mouse eradication should preferentially take place outside of a mast event but would likely still succeed during and following a mast event. Our work fills a key knowledge gap about rodent population trends during mast events for Southern Ocean islands, which is particularly important where eradications are planned.

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Section: Discussionmentioning

confidence: 99%

“…The logistical challenges of completing bait spread at the scale of Auckland Island requires a deviation from current best practice (Horn et al 2022;Livingstone et al 2022;Oyston et al 2022). A lower bait sowing rate (two applications, each of 4 kg ha −1 brodifacoum) and timing operations during summer have been proposed, c.f.…”

Section: Introductionmentioning

confidence: 99%

Population trends of house mice during tussock mast seeding on Auckland Island

Sagar¹,

Cox²,

Horn³

et al. 2022

NZJE

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“…Applying bait in the summer greatly increases the likelihood of completing bait spread because there are more daylight hours and generally more stable weather for helicopter bait spreading (Table 3). These adaptations are supported by the results of a summer bait uptake trial on Auckland Island (Russell et al 2019) and recent successful mouse eradications on Adele Island (87 ha; Livingstone et al 2022) and Maud Island (318 ha; Oyston et al 2022) in winter using substantially lower bait application rates than New Zealand best practice on temperate islands. With the adjustments to the prescription, baiting can be completed by resourcing enough helicopters and pilots and conservatively planning the operational duration based on known weather trends (Table 2).…”

Section: Can It Be Done? All Individuals Of the Target Species Can Be...mentioning

confidence: 86%

“…Development requires construction of replicate cameras using available technology and establishing a work programme for suppliers to build capability . To eradicate mice, the bait bucket mechanism needs improvement to reliably sow 2 g baits at the required low application rates (Russell et al 2019;Livingstone et al 2022;Oyston et al 2022). Agricultural machinery already uses automated variable flow rate integrated with GPS ground speed which is adaptable to bait spread for invasive pests (Alameen et al 2019).…”

Section: Improving Eradication Toolsmentioning

confidence: 99%

The next frontier: assessing the feasibility of eradicating mammalian pests from Auckland Island

Horn¹,

Sagar²,

Frank³

et al. 2022

NZJE

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Auckland Island, the fifth largest island in New Zealand, is the only island in New Zealand's subantarctic region where introduced mammalian pests remain (pigs, Sus scrofa; mice, Mus musculus; cats, Felis catus). The island has unique biodiversity and is a key site for progressing New Zealand's goal to be free of several introduced predators by 2050. Recent island eradication successes have rekindled interest in eradicating pests from Auckland Island, and for the first time considering all three pests in one project. Over a 3-year period, we tested the feasibility of eradicating pigs, mice and cats by looking at what it would take to succeed, rather than what we could practically deliver with the tools we currently have. We proposed adaptations to current methods and used an evidence-based approach by undertaking large-scale field trials to test uncertainties and emerging technologies in-situ. We gathered data and evaluated proposed methods against five established principles of eradication while considering the logistics and infrastructure requirements of the project. Eradicating pigs, mice and cats from Auckland Island is worthwhile and feasible but dependent on further development of emerging technologies and capabilities for efficient delivery with an acceptable level of risk. Three eradication operations are required with specific sequencing and timing, supported by initial establishment of infrastructure. The project needs a large investment spread over 8 to 10 years to yield permanent and internationally important benefits with low ongoing cost to sustain. The feasibility study exposed the project's scale and was used to inform decision makers, who postponed the work in 2020 in response to the economic impacts of COVID-19. The study focusses future preparations on identified planning issues and dependencies to progress project readiness in anticipation of it being launched when economic conditions allow.

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“…Opportunities to test mouse eradication in a breeding population (Russell et al 2019;Horn et al 2022b) and with low sow rates (this paper; Oyston et al 2022) were considered necessary next steps to commit to more ambitious projects.…”

Section: Introductionmentioning

confidence: 99%

How low can you sow? House mouse eradication on Motuareronui/Adele Island

Livingstone¹,

Horn²,

Broome³

et al. 2022

NZJE

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House mice (Mus musculus) are highly invasive mammals and can cause extensive ecosystem damage on islands where they are the sole mammalian pest species. Capability to eradicate mice has improved in recent years. Mouse eradication has been achieved on large islands where mice cohabit with other rodents and islands where mice are the sole mammalian pest. As the islands targeted for eradication become larger and more challenging, reduced toxic cereal bait application rates can reduce both complexity and cost, and ultimately make currently unachievable operations feasible. Auckland Island (45 891 ha) in New Zealand's subantarctic region is a desirable target for mouse eradication. However, logistics at this scale indicate that the required bait volume using New Zealand's currently agreed best practice (two applications, each 8 kg ha −1 ) is not feasible using available resources. Small islands provide an opportunity to experiment with eradication methods with acceptable levels of risk. Here we test the eradication of mice from a small island in New Zealand using a low bait application rate. A single application of 3 kg ha −1 of rodent cereal baits containing brodifacoum was aerially applied on Motuareronui/Adele Island (87 ha) in New Zealand's Abel Tasman National Park, in winter 2017. Intensive monitoring immediately following bait application showed the mouse population rapidly succumbed to the baiting operation. Rodent dog checks 5 months after baiting increased confidence in the operations' success. A mouse was detected and caught 7 months later in a biosecurity trap network, but genetic analysis determined that this mouse was a recent incursion rather than the result of eradication failure. No further mice were caught, and the eradication was declared a success two summers after baiting. This study shows how undertaking, reporting on, and reviewing appropriate high-standard field trials can contribute to the evolution of best practice. This study adds to a growing body of evidence that low application baiting (relative to best practice) can be considered feasible for mouse eradications on islands where the benefits outweigh the risks, and points to further avenues of research to reduce risk and broaden the application of this method.

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A trial on Te Pākeka/Maud Island for reducing aerial baiting sow-rates for the eradication of house mice

Cited by 5 publications

References 18 publications

Population trends of house mice during tussock mast seeding on Auckland Island

Population trends of house mice during tussock mast seeding on Auckland Island

The next frontier: assessing the feasibility of eradicating mammalian pests from Auckland Island

How low can you sow? House mouse eradication on Motuareronui/Adele Island

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