The large-scale removal of mammalian invasive alien species in Northern Europe

Abstract

Numerous examples exist of successful mammalian invasive alien species (IAS) eradications from small islands (<10 km2), but few from more extensive areas. We review 15 large‐scale removals (mean area 2627 km2) from Northern Europe since 1900, including edible dormouse, muskrat, coypu, Himalayan porcupine, Pallas' and grey squirrels and American mink, each primarily based on daily checking of static traps. Objectives included true eradication or complete removal to a buffer zone, as distinct from other programmes that involved local control to limit damage or spread. Twelve eradication/removal programmes (80%) were successful. Cost increased with and was best predicted by area, while the cost per unit area decreased; the number of individual animals removed did not add significantly to the model. Doubling the area controlled reduced cost per unit area by 10%, but there was no evidence that cost effectiveness had increased through time. Compared with small islands, larger‐scale programmes followed similar patterns of effort in relation to area. However, they brought challenges when defining boundaries and consequent uncertainties around costs, the definition of their objectives, confirmation of success and different considerations for managing recolonisation. Novel technologies or increased use of volunteers may reduce costs. Rapid response to new incursions is recommended as best practice rather than large‐scale control to reduce the environmental, financial and welfare costs. © 2016 Crown copyright. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Risk management to prioritise the eradication of new and emerging invasive non-native species

“…with terrestrial species receiving significantly higher scores than aquatics, which broadly reflects the findings of Genovesi (2005), Robertson et al (2016) and Simberloff (2009). Freshwater species generally received low scores; however, eradication was more likely to be feasible if the species occurred in lentic (still) rather than lotic (flowing) systems.…”

“…Bax et al 2002;Culver and Kuris 2000;Wotton et al 2004), and this is reflected in the result for Japanese sting winkle (Ocenebra inornata). We found no correlation between taxa and overall feasibility of eradication in our data; however, terrestrial vertebrates generally received moderate or higher scores for feasibility of eradication, which reflects experience from GB and elsewhere (Genovesi 2005;Robertson et al 2016). When combined with existing risk assessment scores our results demonstrate that the NNRM scheme can be used to prioritise the eradication of large numbers of non-native species across different taxa and environment.…”

The challenges of long‐term invasive mammal management: lessons from the UK

“…Eradications of muskrat Ondatra zibethicus , coypu Myocastor coypus , and Himalayan porcupine Hystrix brachyura were implemented to prevent potential economic losses from agricultural damage. These were among the largest successful mammal eradications worldwide, but required a substantial effort over many years to achieve (Robertson et al ).…”

“…Funding for repeated invasive species control across the same geographic areas year on year is difficult to obtain, yet often some action is necessary to mitigate damaging impacts. Management strategies that encompass a broader geographic scale are more cost‐effective (Robertson et al ), can take account of natural boundaries of suitable habitats (Goldstein et al ) and geographic barriers (such as elevation or coastlines), and can help reduce the likelihood or frequency of reinvasion of a cleared area (Robertson et al, ). Defining the appropriate ecologically meaningful scale depends on the species and its interaction with the landscape.…”

Quantifying site-level usage and certainty of absence for an invasive species through occupancy analysis of camera-trap data

“…When the objective of management is complete removal, but there is reinvasion potential, the terminology for invasive species work ranges from control (Allendorf and Lundquist 2003), area-wide suppression (Myers et al 2000), complete removal (Robertson et al 2016), to extirpation (Edge et al 2011;Parkes et al 2017). Using the term 'control' does not distinguish between objectives where complete removal is desired versus some other intensity of removal.…”