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This study analyzed 20 years of invasive American mink control data in relation to water vole populations, revealing that resident adult mink have far greater negative impacts on water voles than transient individuals, with effects extending up to 20 km versus only 2 km respectively. Long-term predator control altered mink demographics and spatial distribution, with water voles benefiting primarily from reductions in resident mink rather than overall mink population decreases. The research demonstrates that considering individual-level variation in invasive predators, rather than total abundance alone, provides more accurate assessment of conservation outcomes.
Why it matters
The findings suggest that targeted removal of specific problem individuals (resident mink) could be more effective than blanket eradication efforts, potentially optimizing limited conservation resources. This framework can inform spatially explicit management strategies for invasive species control by establishing empirically-based buffer zones around vulnerable native populations.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
1. When eradication is unfeasible, invasive predator control should evaluate how removal affects ecological responses by native species. Assessments often use total invasive predator abundance to evaluate prey responses, yet intraspecific variation in diet and space use means that some subgroups cause disproportionate impacts. Identifying these problem individuals, and the spatial scales over which their impacts operate, can enable targeted spatially explicit removal to maximise impact reduction. However, despite individual-level information is often already collected during trapping operations it is seldom included when analysing predator impacts, potentially biasing the conservation outcomes expected under blanket removal. 2. We use a novel framework and two decades of invasive predator control data to estimate how individual variation in residency status influences the distance-dependent impacts of invasive American mink Neogale vison on water vole Arvicola amphibius occupancy across two prey surveys. We also develop a sub-model to predict mink residency status for individuals with missing age data. 3. The probability of capturing adult mink decreased with elevation and years of control, indicating that long-term control altered the resident population and demographic composition of mink around water vole sites. 4. Distance-dependent negative impacts of mink varied by residency status, becoming negligible at approximately 20 km from water vole sites for resident mink and 2 km for transient. The spatial scale of mink impacts was largest during the first vole survey when resident mink were more abundant, and declined rapidly for the second survey, when mink were less abundant and spatially clustered. Our results suggest that water voles have benefited mostly from reducing resident mink rather than the total population, especially in early control phases. 5. Managers can use our framework to develop spatially explicit and impact-based strategies, not restricted to invasive species control, to construct empirically informed management buffers around populations of conservation concern. Long-term efforts will change the landscape and invasive predator contexts, and thus we recommend iteratively updating and re-evaluating management outcome evaluations. We argue that incorporating individual heterogeneity improves our understanding of ecological mechanisms influencing management success but that the suitability of targeted strategies should be evaluated for target socioecological contexts.
Source: One scale does not fit all: invasive predator identity determines the impact on native prey