The American mink in Europe: status, impacts, and control

Biological Conservation (Impact Factor: 3.79). 11/2007; 134:470-483. DOI: 10.1016/j.biocon.2006.09.006

ABSTRACT We examine the distribution of American mink Mustela vison in 28 European countries, and we review the impacts of this invasive species and the efforts made so far in controlling it. Our study reveals that, although mink farms are mostly concentrated in northern countries, mink are widely distributed across Europe, and that in some countries mink are apparently declining, although in most cases the causes are unknown. Countries for which the impact of mink on native species has been studied show that mink can have a significant effect on ground-nesting birds, rodents, amphibians and mustelids. The overall economic impact of feral mink seems to be relatively small but can be significant in specific regions. Recently, a number of eradication and local control projects have been carried out throughout Europe, indicating that these actions could be effective to protect native species. A consistent body of knowledge is starting to accumulate on issues concerning the American mink as an invasive alien species, but, as this review highlights, for most European countries there is currently a limited knowledge about its distribution or impacts. Taking all these observations together, we present some of the actions that have recently emerged as effective for dealing with this species and discuss which considerations may further encourage competent European authorities to take action to prevent and mitigate impacts of American mink.

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    ABSTRACT: Background SNH’s Hebridean Mink Project (HMP) uses intensive and systematic trapping by professional trappers to achieve eradication of American mink (Neovison vison) in the Western Isles. Phase 2 of the project started in 2007 and is scheduled to end in March 2014. It implements a standardised trapping regime over multiple years, so a large data set has been assembled which can be used to inform management decisions in the HMP area as well as in other areas where mink eradication is envisaged. Statistical analyses of these data to date have been limited. The aim of the present project was to optimise the amount that can be learned from the HMP by providing a scientific analysis of what has happened to the population of mink in the Outer Hebrides during the project. It also aimed to examine how the findings can be applied more widely and in future mink control schemes elsewhere in areas where similar habitats are occupied by mink. Main findings A hierarchical statistical model based on capture histories of mink caught in four habitat compartments over three seasons fitted to the HMP data yielded credible estimates of the number of individuals that escaped capture and of demographic parameters of the culled mink population. In the model, mink that escape capture in the fraction of a given habitat trapped during a given season, as well as those mink in the non-trapped portion of that habitat compartment, contribute to the population in the next season. These mink may survive, reproduce and/or move between compartments. The daily probability that a mink in the vicinity of open traps was caught varies between 0.15 and 0.30, increasing over the study years. A probability of capture of 0.3 implies that about 24% of females present in an area escape trapping after 4 days. There was no evidence of evolving trap-shyness under selection imposed by trapping. It is estimated that there is a mean of 0.33 independent female offspring per adult female and almost no mortality due to causes other than trapping. There are very high movement rates between habitats by individuals or their offspring, especially during the summer to winter transition. A high proportion of these individuals were found to move into the large mountain and moorland compartment which was treated as a single habitat type in this report We estimated there were 350 females in SPRING 2008. Our last reliable estimate is that 61 females bred in 2011 across the whole of HMP area. The number of breeding females was estimated to have been reduced by approximately 80% in 4 years. The rate of decline of the mink population in each habitat was roughly constant from 2009-2010, but slowed down in 2011 relative to previous years. The statistical model, which fully accounts for all sources of uncertainty, yields a wide range of predictions on the dynamics of the Lewis and Harris mink population beyond 2011. The possibilities that the population recovered in late 2012 or is nearly extinct are both consistent with the data at hand. A model initialised with mink population size from SPRING 2011 and ignoring the uncertainty around demographic rates, was used to simulate the likely outcomes if systematic (as opposed to reactive) trapping had continued beyond 2011. This yields a distribution of likely times to extinction with the earliest extinctions occurring in 2014 and the latest in 2021. The most common outcomes are the Lewis and Harris mink population would have gone extinct in 2015 or 2016. In 80% of simulations mink had gone extinct by 2017. Those dates could be brought forward if the current trapping regime was more effective, but no data were available to explore whether this is the case. The key features that affected success are the combination of high mink mobility, the fact that not all mink are caught in a trapping session and, crucially, the fact that only a fraction of a habitat compartment could feasibly be trapped in a season. Thus scenarios involving redeployment of trapping effort to maximise the proportion of habitat trapped in two seasons, shorter trapping sessions, no trapping in one season, and reduced trapping in the habitat with highest emigration rate hasten extinction. Modelling approaches similar to those used here could be applied to data with a different structure but this would require substantial further model development.
    01/2014: pages 42; Scottish Natural Heritage.
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    ABSTRACT: Understanding changes over time in the distribution of interacting native and invasive species that may be symptomatic of competitive exclusion is critical to identify the need for and effectiveness of management interventions. Occupancy models greatly increase the robustness of inference that can be made from presence/absence data when species are imperfectly detected, and recent novel developments allow for the quantification of the strength of interaction between pairs of species. We used a two-species multi-season occupancy model to quantify the impact of the invasive American mink on the native European mink in Spain through the analysis of their co-occurrence pattern over twelve years (2000–2011) in the entire Spanish range of European mink distribution, where both species were detected by live trapping but American mink were culled. We detected a negative temporal trend in the rate of occupancy of European mink and a simultaneous positive trend in the occupancy of American mink. The species co-occurred less often than expected and the native mink was more likely to become extinct from sites occupied by the invasive species. Removal of American mink resulted in a high probability of local extinction where it co-occurred with the endemic mink, but the overall increase in the probability of occupancy over the last decade indicates that the ongoing management is failing to halt its spread. More intensive culling effort where both species co-exist as well as in adjacent areas where the invasive American mink is found at high densities is required in order to stop the decline of European mink.
    Biological Conservation 08/2014; 176:21–29. · 3.79 Impact Factor
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    Conservation Biology 02/2014; · 4.36 Impact Factor


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May 28, 2014