Landscape-scale eradication of American mink: a successful feasibility trial

Abstract American mink were functionally eradicated from 5853 km 2 of eastern England within three years of the initiation of a comprehensive, strategically managed trap network operated by volunteers under professional supervision. The mink population had previously been much reduced by less intensive trapping over many years, but would have persisted if a more coordinated operation, including the introduction of a trapped cordon sanitaire to greatly reduce immigration, had not been set up. Trapping utilised ‘live’ cage traps placed on floating rafts and equipped with electronic monitoring devices. These ‘smart’ traps quickly alerted trappers to each door closure, initiating a prompt trap visit and either the humane dispatch of a mink or rapid release of a healthy non-target animal. The year-on-year decline in Catch Per Unit Effort (no. mink caught per 1000 trap nights), a good proxy for mink density, varied between 73 and 100%. It appears that the mechanism of eradication is lack of reproduction; no evidence of reproduction was found in the final 10 females caught in summer, when they would normally have shown signs of pregnancy or lactation. Having been dominant in the catch in the years preceding the study, males were scarcely caught during it. The most parsimonious explanation for reproductive failure is that females did not encounter a mate during their relatively short receptive period. This study demonstrates that American mink can be humanely eradicated from vast areas of Europe in a relatively short period of time and with little or no negative impact on non-target animals.