Scottish Invasive Species Initiative — American Mink Control for Water Vole Recovery (UK)

American mink (Neovison vison), escaped or released from fur farms across Britain, are the main driver behind a historic decline of more than 90% in the range of the water vole, the UK's fastest-declining native mammal. Scotland's response began with the Scottish Mink Initiative (2011-2015), a £920,000 programme covering 20,000 km² of Tayside, Aberdeenshire, Moray and the Cairngorms, later expanded to 30,000 km² with a network of more than 480 volunteers.

Since 2017 the Scottish Invasive Species Initiative (SISI), led by NatureScot, has scaled this approach across roughly 3 million hectares of northern Perthshire, Angus, Aberdeenshire, Moray and Highland. Its first phase (2017-2023) was funded by the National Lottery Heritage Fund (£1.59M) and NatureScot (£0.5M) plus in-kind contributions, for a total project value of £3.34M; a second phase (2023-2026) is backed by a further £2.08M from the Scottish Government's Nature Restoration Fund. More than 500 volunteers now operate over 600 mink rafts and traps.

Interim figures show 71 mink removed by December 2018, rising to 109 by June 2019. SISI itself reports anecdotal recovery of previously extinct local water vole populations, though no published cumulative population count is available.

A peer-reviewed comparator study from England's River Monnow catchment found mink removal a necessary but not sufficient condition for water vole persistence, with releases of captive-bred voles still needed to sustain a recovering population. The programme's own materials note that mink quickly recolonise trapped areas from nearby populations if coverage lapses, meaning sustained, large-scale trapping is required rather than a one-off campaign. Even long-running English efforts modelled on Scotland's approach have recorded unconfirmed mink sightings years into near-zero catch rates, underlining how hard full eradication is to prove.