User:Jonathan C Reynolds/sandbox

Mink raft

A mink raft is a device developed by scientists at the Game & Wildlife Conservation Trust (GWCT) to detect the presence of American Mink, an ecologically damaging invasive alien species in Europe and other countries around the world. Rafts are deployed at intervals along rivers and other water courses, where they are explored by the naturally inquisitive mink. A simple natural medium housed under a tunnel on the raft records footprints of visiting mink (and other animals). Mink often make return visits to the same raft, which can therefore also be used as a trap site. This leads to a highly focussed and effective lethal control programme, with demonstrated benefits for native prey species.

Development
Prototype mink rafts were developed by GWCT scientists Jonathan Reynolds and Mike Short during 2002-2003, originally as a research tool. The concept arose from the fact that mink were rarely seen when present, and were usually surveyed by looking for characteristic field signs (footprints and faeces) in likely locations such as mid-stream rocks, muddy shores or under bridges. However, on some rivers these kind of locations can be very widely spaced, and may not be present at all. The basic idea of the mink raft was to artificially provide a small patch of footprint recording medium in an appealing structure at intervals along the river. Footprint recording was already an established method used to detect other mustelid species, usually on paper using ink or a chemical reaction. Given that mink in this habitat are likely to be wet, paper was not an ideal recording medium. The inventors chose instead to use something resembling natural river mud, developing a standardised medium that could be mixed to the right consistency from dry sand and wet potters' clay. The problem was how to keep the recording medium in a receptive state, as the exposed recording medium could be washed out by a rise in water level, or conversely dry out and become unreceptive. Experience during the coypu eradication campaign in the 1970s, recorded by Baker et al ####, had shown that mink were keen to explore small floating structures. The mink raft is designed to hold a shallow 1 cm layer of recording medium approximately 2 cm above the water level. The medium is kept moist by using flower-arranging foam (Oasis) to wick water up by capillary action from beneath the raft.

The finished design was trialled on the River Avon, Hampshire (southern central England) in 2004. This was one of the first rivers colonised by mink in the 1950s, and the site of an early failed eradication attempt by the Ministry of Agriculture, Fisheries and Food. In 19##, an estimated 6,000 mink were released by animal rights activists from a fur farm close to the river at Ringwood. This provoked a higher level of trapping by some individuals; but others admitted to being disillusioned, either because they rarely caught mink, or because there seemed to be no end to the problem.