Stoat invasion, eradication and re-invasion of islands in Fiordland

Elliott, Graeme; Willans, Murray; Edmonds, Hannah; Crouchley, David

doi:10.1080/03014221003602166

Cited by 18 publications

(17 citation statements)

References 3 publications

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“…They are the primary nest predator in both alpine grasslands and beech forests (Smith et al 2008) and they are a primary agent of decline for over half of all forest birds of New Zealand currently threatened or significantly declining (Innes et al 2010). They pose one of the highest invasion risks to islands (Elliott et al 2010;Veale et al in press). There are numerous eye witness accounts of stoats swimming hundreds of meters from shore (Wodzicki and Bull 1951;Fitzgerald 1978;King and Moors 1979) and swimming is believed to be their primary island invasion pathway (Taylor and Tilley 1984;Veale et al in press).…”

Section: Introductionmentioning

confidence: 96%

Genetic population assignment reveals a long-distance incursion to an island by a stoat (Mustela erminea)

2011

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When new individuals from a pest species are detected after an eradication programme, it is important to determine if these individuals are survivors from the eradication attempt or reinvaders from another population, as this enables managers to adjust and improve the methodologies for future eradications and biosecurity. Rangitoto/Motutapu Islands in the Hauraki Gulf (New Zealand) had a multispecies mammalian pest eradication conducted in 2009. A year after this eradication a single stoat was trapped on the island. Using genetic population assignment we conclude that this individual was a reinvader, which probably swam a minimum distance of 3 km from the adjacent mainland. This swimming distance is greater than any previously known stoat incursions. Our results suggest that the original population on these islands was from natural dispersal rather than anthropogenic introduction and that it had some limited ongoing mixing with the mainland population. These findings highlight the invasion/reinvasion potential of stoats across large stretches of water, and will necessitate ongoing biosecurity indefinitely for these islands. The study also highlights the utility of genetic assignment techniques for assessing reinvasion, and emphasizes the need for pre-eradication genetic sampling of all pest species to enable such analyses to be carried out.

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Section: Introductionmentioning

confidence: 96%

Genetic population assignment reveals a long-distance incursion to an island by a stoat (Mustela erminea)

2011

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“…There, culling in all years should have a real chance of reducing the local density of stoats below the local carrying capacity, even to local extinction. Indeed, local extinction has been achieved on some islands, even where immigration is still possible (McMurtrie et al in press;Elliott et al 2010). At Pureora, the density index for stoats declined after the first year of trapping, and remained low for the following 4 years (King et al 1996b).…”

Section: Effects Of Culling On Long-term Population Dynamics Of Stoatsmentioning

confidence: 97%

Managing an invasive predator pre-adapted to a pulsed resource: a model of stoat (Mustela erminea) irruptions in New Zealand beech forests

King

Powell

2011

Biol Invasions

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The stoat (Mustela erminea) is a specialist predator that evolved to exploit the unstable populations of northern voles and lemmings. It was introduced to New Zealand, where it is pre-adapted to respond with a population irruption to the resource pulses that follow a heavy seedfall of southern beech (Nothofagus spp.). Culling stoats during an irruption is necessary to reduce damaging predation on nesting endemic birds. Culling might not reduce the stoat population long term, however, if high natural mortality exceeds culling mortality in peak years. During other phases of the beech-mast cycle, culling might have a greater effect on a smaller stoat population, whether or not damage prevention is critical. We developed a 4-matrix model to predict the effects of culling on k, the annual rate of change in the size of the stoat population, through the four annual phases of an average masting cycle, explicitly distinguishing between apparent and real culling. In the Post-seedfall phase of the cycle, large numbers of stoats are killed, but little of this extra mortality is additive; in other phases, culling removes larger proportions of smaller total numbers of stoats that would otherwise have lived. Culling throughout all phases is most effective at reducing stoat populations, but is also the most expensive option. Culling in Postseedfall plus Seed or Crash years is somewhat less effective but better than culling in one phase only. Culling has different short-term effects on stoat age distribution depending on the phase of the cycle when culling begins.

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“…In line with previous stoat eradications (Elliott et al 2010;McMurtrie et al 2011), the trap network was pre-baited (baited but traps not set) twice prior to the rodent eradication to minimize any potential for neophobia. Traps were initially baited with fresh rabbit meat and a single hen's egg to target stoats, but from December 2009 were baited with a variety of different bait types for hedgehogs.…”

Section: Trappingmentioning

confidence: 98%

“…The proposed grid was more intensive than those used in past successful stoat eradication attempts (Elliott et al 2010;McMurtrie et al 2011) because of the need to also target hedgehogs.…”

Section: Stoatsmentioning

confidence: 98%

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

Griffiths¹,

Buchanan²,

Broome³

et al. 2014

Biol Invasions

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An eradication program conducted on Rangitoto and Motutapu islands in New Zealand successfully removed stoats (Mustela erminea), cats (Felis catus), hedgehogs (Erinaceus europaeus occidentalis), rabbits (Oryctolagus cuniculus), mice (Musmusculus) and three species of rat (Rattus, R. exulans and R. norvegicus) from an area of 3,842 ha. The project was significant because it was completed so close to Auckland, New Zealand's largest city, but also, in contrast to many eradication projects, it targeted a suite of invasive mammals in a single operation. To achieve success and avoid conflict in the allocation of resources, target species were prioritized by likelihood of eradication success with resources allocated preferentially to species posing the greatest risk of failure and methods applied in a sequence that allowed each technique to capitalize on its predecessor. Consequences of applying this approach were increased operational efficiency, a shorter operation than planned and reduced project cost. When compared to other projects that targeted the same species but individually, we estimate the Rangitoto and Motutapu project to have cost less than 50 % of the total potential cost if each species had been removed in a discrete operation. Logistical efficiencies created by condensing several operations into one and the use of eradication and detection techniques that targeted multiple species are credited as having the greatest influence on the increased efficiencies observed.

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Stoat invasion, eradication and re-invasion of islands in Fiordland

Cited by 18 publications

References 3 publications

Genetic population assignment reveals a long-distance incursion to an island by a stoat (Mustela erminea)

Genetic population assignment reveals a long-distance incursion to an island by a stoat (Mustela erminea)

Managing an invasive predator pre-adapted to a pulsed resource: a model of stoat (Mustela erminea) irruptions in New Zealand beech forests

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

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