In this month’s Gosforth Nature Reserve Journal, NHSN naturalist, Christopher Wren, takes a closer look at the invasive American Mink and the impact on native wildlife.
Non-native invasive mammals have caused havoc to native wildlife across the world. Populations of introduced Stoats in New Zealand have devastated the local ground-nesting birds since the nineteenth century, and closer to home and more recently, Hedgehogs in the Outer Hebrides and Stoats in Orkney have caused similar problems. On the British mainland the two most damaging non-native mammals are American Grey Squirrels and American Mink. The squirrels were introduced, also in the nineteenth century, and have since displaced native Red Squirrels from large parts of the country. American Mink escaped or were maliciously released from fur farms in the 1950s and 1960s and are now found in all parts of the country apart from northern Scotland and some islands. Farmed mink were bred in a variety of colours but the feral population has mainly reverted to the natural dark brown colour.
Mink are semi-aquatic mammals, members of the Mustelid family that includes, Weasels, Stoats, Polecats, Pine Martens, Otters and Badgers. They eat small mammals, kingfishers, sand martins, birds ’eggs, frogs, crayfish, and fish and have been responsible for a 94% reduction in the numbers of our native Water Voles.
We only occasionally see mink in Gosforth Nature Reserve, three times in the past 10 years as far as I am aware. There is some evidence that mink avoid areas where there is a strong otter presence so our resident otters may be helping to discourage them. When a mink has appeared in the reserve it has been detected on a trail camera before any other evidence of its presence.
A mink is much smaller than an otter, has a furrier tail and swims with a “doggy paddle”, much higher in the water. This video shows a swimming mink.
Eradication of American Grey Squirrels from Great Britain looks to be an impossible task but there is a glimmer of hope as far as American Mink are concerned. Mink are easy to trap but live traps have to be checked once or twice a day, making it a laborious and expensive enterprise. The recent introduction of smart traps which alert the trapper by text message and email when the trap is sprung have proved to be 100% reliable and have reduced the workload by 97%. Using scent-baited smart traps mink have been almost completely eliminated from East Anglia in a very short time and the programme is being rolled out to adjacent areas and other parts of the country.
For more information about American Mink, please visit the links below:
https://mammal.org.uk/blog/2021/05/smart-mink-traps-by-tony-martin-invasive-species-week
https://mammal.org.uk/blog/is-eradication-of-invasive-mink-now-possible