Mink in Assynt?
The number of American mink, Neovison vison, sightings in the northern Highlands has been steadily increasing in the last few years. A badly decomposed carcass was found on a farm on Loch Eriboll, Durness. This was confirmed to be an American mink by the University of Aberdeen. Examination of the skull makes it possible to identify between mink, ferret and pine marten. Each species’ skull has unique fissure lines and bone plates which can be used to identify a carcass from a long-dead specimen.
Since this discovery in 2011, there have been numerous sightings around Durness, Loch Eriboll and as far east as Bettyhill. Then, a live mink was captured and humanely destroyed in Assynt near Kylesku. South of Assynt there has been several records from Achiltibuie. In February 2012 a mink was seen, and later captured, on Tanera Mor, one of the Summer Isles. A small number were killed around the Gruinard area in March 2012 and then one in Contin in April 2012.
Mink rafts
Due to the increased activity in areas previously believed to be free of American mink, it was decided that Mink Officer, Gunnar Sholtz, should spend time assessing the size of the American mink population in Assynt. A large number of Mink rafts have been placed in likely places around Assynt. These rafts are designed to record the presence of mink using a clay surface to record footprints. Volunteers check them weekly for any signs of mink. Both Stoer and Lochinver Primary Schools monitor a raft for the Mink project.
On 21st March 2012 several of the children from Lochinver Primary discovered footprints on their Loch Culag raft. Experts are fairly sure the prints are those of a Mink. A live trap has now been set and we await news.
Alien species
The American mink is an alien species to Scotland, being native to North America. Once established in an area they create havoc with the regional wildlife. They cause the local extinction of water voles and the severe depletion of ground nesting birds such as terns and common gulls.
One of the aims of the Scottish Mink Initiative is to eradicate breeding mink from the far North of Scotland. That should help protect our nationally significant populations of water voles, salmonids, ground nesting birds and other aspects of native riparian biodiversity.
For more information or if you think you see a mink please contact Shona Marshall, West Sutherland Fisheries Trust at wsft@btconnect.com.
Oban conference
A recent presentation at the Scottish Ornithologists Club conference in Oban was delivered by Clive Craik of the Scottish Association for Marine Science. Clive highlighted the destructive power of mink with particular reference to breeding bird populations.
Clive has spent over 25 years studying mink and their impact on common gull and tern colonies on islands off the west coast of Argyll. He also has been involved in the setting up of tern rafts which have proved very successful in minimising the loss of terns due to mink predation.
Some of the photographs here are by Clive and show the devastating effect of mink on gull and tern colonies. These kills were, in each case, carried out by a single mink in one night with one bite to the back of the head/neck of the bird. Once the mink has killed it caches its food for future consumption. Unfortunately, in many cases the the dead birds are hidden in seaweed. The next high tide often washes the carcasses away meaning the mink has to kill again!
Mink, being generalist predators, will once they have found a food source, rapidly kill everything present. This can very quickly cause the complete failure of breeding success and drive the birds, voles, etc. to local extinction.
Sadly Assynt’s off-shore bird colonies are not safe from predation. Work by Clive has shown that the safe distance is around one kilometre. Most of our Assynt’s islands are therefore well within reach of these semi-aquatic carnivores.
UPDATE
As of 19th April 2012 nothing has been trapped at Loch Culag. However, on 16th April the mink raft in Little Assynt was visited and found to have several possible mink prints on the clay. It is likely that live traps will now be set here to see what turns up. Also, there has been a positive sighting of mink on Handa Island. Although not Assynt this is a worrying development as auks, terns and other nesting birds are returning for the breeding season.
D.Haines