Successful eradication of invasive vertebrates on Rangitoto and Motutapu Islands, New Zealand

Griffiths, Richard; Buchanan, Fin; Broome, Keith; Neilsen, John R.; Brown, Derek; Weakley, Michelle

doi:10.1007/s10530-014-0798-7

Cited by 29 publications

(32 citation statements)

References 26 publications

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“…by-kill of some of the predators followed by ground control to remove survivors (Griffiths et al 2015); and (iv) a growing intent to tackle islands inhabited by people (Glen et al 2013a). …”

Section: Control Of Possums As Vectors Of Bovine Tuberculosismentioning

confidence: 99%

“…The major issue for the predator-free model is whether survivors can be removed by niche control tools: they can be removed but usually at considerable cost (e.g. Griffiths et al 2015).…”

Section: Can 100% Of Targeted Populations Be Reliably Removed?mentioning

confidence: 99%

“…Based on the costs of the successful multispecies eradication on Rangitoto/Motutapu Islands (Griffiths et al 2015), the minimum cost to eradicate ship rats, mice, stoats and possums (and maybe cats and other predators) from the three main islands of New Zealand would be $1200 per ha. Across all of New Zealand this equates to about $32 billion or 15% of New Zealand's GDP.…”

Section: Rolling Out the Campaign In Space And Timementioning

confidence: 99%

See 2 more Smart Citations

Past, present and two potential futures for managing New Zealand’s mammalian pests

Parkes¹,

Nugent

Forsyth

et al. 2017

NZ J Ecol

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Abstract:In 2003, a review of how introduced mammals were managed as pests in New Zealand was published. Since then trends for the control of these mammals include moves from pest-by-pest prioritisation towards site-based and multiple-pest management, extension of large-scale aerial control of predators to include beech forests, increasing intensive management of sites by private and non-government agencies, and increasing effort by regional councils and managers of vectors of bovine tuberculosis. The current deployment is the sum of largely independent decisions made by different agencies and individuals with different priorities. National agencies might optimise their own decisions, but overall deployment will always be nationally suboptimal when objectives are set at regional or local scales. This system includes both small areas where most of the mammals present are managed intensively and large areas where fewer species are managed. We discuss how this deployment might evolve as a network of smaller core areas aiming to achieve zero or low densities of all or most pests, with surrounding halos with lesser control effort against fewer species, enough to allow for at least 'safe passage' of native animals between the cores. This system might work best along the more-or-less contiguous native habitats along the axial ranges of the North and South Islands, especially if agencies with a national mandate are prepared to act in the extensive areas between core sites. Some have asked whether the successful eradication of mammals on small islands can be scaled up to the main islands of New Zealand. The current version of this predator-free model aims at the ubiquitous ship rat, brushtail possum and stoat. A key need for the predator-free model is a tool that kills 100% of each of the three main target species, ideally with one large-scale, socially-acceptable application. Without this tool the cost to find and kill survivors would raise the costs of national eradication to about $32 billion, assuming current costs of multiple-species eradications on islands. For sustained control options, research is needed to inform the frequency and intensity of control, and thus the best control tools. The ability to detect target pests at low densities and management of reinvasion are essential for achieving zero or low pest density goals. We suggest that the core/halo model of pest management, within a network of assets to be protected, will best protect New Zealand's biodiversity for the foreseeable future. The national scale pest-or predator-free aspiration is not currently (and may never be) feasible and risks diverting resources from more optimal solutions, as occurred with the 'last rabbit' and 'last deer' programmes promoted last century.

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Section: Control Of Possums As Vectors Of Bovine Tuberculosismentioning

confidence: 99%

“…The major issue for the predator-free model is whether survivors can be removed by niche control tools: they can be removed but usually at considerable cost (e.g. Griffiths et al 2015).…”

Section: Can 100% Of Targeted Populations Be Reliably Removed?mentioning

confidence: 99%

Section: Rolling Out the Campaign In Space And Timementioning

confidence: 99%

See 1 more Smart Citation

Past, present and two potential futures for managing New Zealand’s mammalian pests

Parkes¹,

Nugent

Forsyth

et al. 2017

NZ J Ecol

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show abstract

“…The implementation or operational cost 2 to aerially sow brodifacoum baits (Broome et al 2014) against rodents averaged c. $300 ha -1 for New Zealand projects on uninhabited islands (e.g. for Campbell Island see McClelland (2001); for Rangitoto-Motutapu Islands see Griffiths et al (2015); and for Raoul, Little Barrier and Hen Islands see Holmes et al (2016) and references therein). However, costs on inhabited or farmed islands can be much higher as a consequence of having to work around people and livestock, e.g.…”

Section: Costsmentioning

confidence: 99%

“…The cost to remove survivors is variable, and of course depends on the number of non-rodent species present, but is usually high. For example, on Rangitoto-Motutapu Islands, the cost to remove and validate success for the four non-rodent species (stoats, cats, hedgehogs and rabbits) was about the same as to remove the rodents (Griffiths et al 2015) -with sobering extrapolations for attempting the whole of New Zealand with current methods (Parkes et al 2017). Eradicating cats, stoats, pigs and possums requires different strategies and tools for each species, although of course where they are sympatric there are some costs shared between the species if they are managed simultaneously.…”

Section: Costsmentioning

confidence: 99%

Eradicating mammals on New Zealand island reserves: what is left to do?

Parkes¹,

Byrom²,

Edge³

2017

NZ J Ecol

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Abstract:In 2016, the New Zealand Government announced a policy to rid the country of key introduced predators (possums (Trichosurus vulpecula), ship rats (Rattus rattus), Norway rats (R. norvegicus) and mustelids (Mustela spp.)) by 2050. An interim goal under this policy is to remove all mammalian predators (the key species as well as mice (Mus musculus), kiore (R. exulans), cats (Felis catus), pigs (Sus scrofa) and hedgehogs (Erinaceus europaeus)) from island nature reserves by 2025. We identify the New Zealand islands over one hectare managed as reserves by the Department of Conservation (DOC) that have mammalian predators that can be eradicated. There are over 850 islands, islets, stacks and vegetated rocks in the New Zealand archipelago. We exclude islands in lakes and rivers and those smaller than one hectare, which leaves 616 islands, less than half of which are under some form of reserve status (286 islands entirely managed by DOC and 13 under mixed tenures but with some reserve land). One or more mammalian predators are known to occur on 48 of these islands, with the Government's 2050 target species on 42 islands and other predators (in the absence of the target species) on six islands. The Government's 2025 goal nominates one class of reserve, nature reserves. Of the 48 islands, just four islands are classed as nature reserves -two (Mauitaha and Araara Islands) with protected kiore in the Hen and Chickens group and two in the Auckland Islands group (Auckland with mice, cats and pigs; and Masked with mice and cats) -i.e. none with the key species of the wider 2050 goal. Therefore, we consider other reserve classes but place more or less strict risks of reinvasion, as indexed by known swimming ranges of the predators, to judge the feasibility of eradication. Relaxing the reserve class of the island, but not our selection of swimming ranges, results in 15 candidate islands where all mammalian predators present could be eradicated for the 2025 interim goal. Decisions on which islands to select for the programme need to consider costs and other constraints to eradicate different combinations of predators, and whether the island and its predators provide templates for the wider vision of a predator-free New Zealand, i.e. whether any of the key 2050 predators are present, the size of the island, and/or the presence of human inhabitants that complicate the predators to be targeted or constrain the use of some control methods.

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Disentangling effects of invasive species and habitat while accounting for observer error in a long‐term amphibian study

et al. 2019

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The invasive American bullfrog (Lithobates catesbeianus) and a variety of non‐native sport fish commonly co‐occur in lowland lentic habitats of the western United States. Both invasive taxa are implicated in declines of native amphibians in this region, but few long‐term studies of communities exist. Further, field studies of invasive–native interactions are complicated by confounding habitat modifications and observation errors. We surveyed amphibians and measured habitat characteristics for 12 yr across 38 wetland sites within the Willamette Valley, Oregon, USA. We assessed the influence of invasive species, habitat, and their interactions on the distributions of five native amphibian species using a multispecies dynamic occupancy model that accounted for false‐negative and false‐positive detections. In general, habitat characteristics—such as within‐pond vegetation cover, surrounding forest, and drought severity—were important for local persistence of native species when bullfrogs co‐occurred. We also found evidence of a cumulative negative effect of bullfrogs and non‐native fish (families Centrarchidae and Ictaluridae) on northern red‐legged frog (Rana aurora) local persistence that was mediated by the dominance of invasive reed canarygrass (Phalaris arundinacea). Non‐native fish and bullfrogs had variable effects on native amphibian species, but neither invasive taxon appears to be causing declines in occupied sites within our study area. Moreover, species relationships with habitat differed when invaders were present, indicating that certain habitats may increase persistence of native amphibians in the invaded landscape.

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Successful eradication of invasive vertebrates on Rangitoto and Motutapu Islands, New Zealand

Cited by 29 publications

References 26 publications

Past, present and two potential futures for managing New Zealand’s mammalian pests

Past, present and two potential futures for managing New Zealand’s mammalian pests

Eradicating mammals on New Zealand island reserves: what is left to do?

Disentangling effects of invasive species and habitat while accounting for observer error in a long‐term amphibian study

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