Removal of American mink (Neovison vison) from the Uists, Outer Hebrides, Scotland
Removal of American mink (Neovison vison) from the Uists, Outer Hebrides, Scotland
S. S. Roy . A. L. M. Chauvenet . P. A. Robertson 0 1 2 3
0 A. L. M. Chauvenet School of Biological Sciences, University of Queensland , Brisbane, QLD 4072 , Australia
1 Present Address: S. S. Roy International Union for the Conservation of Nature , 28 Rue Mauverney, 1196 Gland , Switzerland
2 S. S. Roy (&) A. L. M. Chauvenet P. A. Robertson National Wildlife Management Centre, Animal and Plant Health Agency , Sand Hutton, York YO41 1LZ , UK
3 P. A. Robertson Centre for Wildlife Management, School of Biology, Newcastle University , Newcastle upon Tyne NE1 7RU , UK
Since escaping from fur farms in the 1950s, American mink had colonised the 2800 km2 archipelago of the Outer Hebrides of Scotland. Between November 2001 and June 2006 the species was removed from a total of 850 km2 of the southernmost islands, collectively named the Uists, as part of a pilot study exploring the feasibility of large scale eradication throughout the archipelago. Animals were also con2 trolled in neighbouring South Harris (255 km ) to reduce the risk of recolonisation. The project used two main methods, the operation of coastal and riparian cage traps; and trapping at breeding dens located using trained dogs. In the Uists this resulted in 100,824 trap nights over 4 years. Den searches were carried out over 500 handler-days. Overall a total of 228 mink was caught in The Uists, with the last capture in March 2005. After this date, despite a further 7 months of intensive trapping and searching effort, no further signs of mink were found and they were considered likely to have been removed from this region. In the buffer area of South Harris, 41,674 trap nights over 4 years resulted in 240 captures with few animals being caught by the end of the project. This effort greatly reduced the risk of recolonisation from this region, although there was still a possibility of extant isolated populations remaining within the region, particularly on offshore islets, which would then be detected and trapped by a follow up programme. An adaptive management process resulted in significant increases in trapping efficiency. Improvements included optimisation of trap spacing and the frequency and duration of trap-line operation; improvements in the cage designs and use of lures. The protocols developed here were used in the subsequent eradication campaign in the remainder of the Outer Hebrides.
Invasive alien species; Removal; Wildlife management; Mink; Outer Hebrides
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Habitat loss and non-native species are considered the
two most important threats to global biodiversity
(Vitousek et al. 1997). Invasive carnivores have
caused substantial biodiversity loss, particularly on
islands (Nogales et al. 2013). The American mink
Neovison vison is a widely distributed invasive
carnivore, occurring in 28 European countries, The
eradication of invasive Mustelids in general can be
challenging (King et al. 2009), and most mink control
operations in Europe are long-term control operations
rather than eradications, for example in Iceland
(Bonesi and Palazon 2007) or at a local catchment
level in England (Reynolds et al. 2004).
Mink populations were established on the Outer
Hebrides of Scotland when animals escaped, or were
deliberately released, from fur farms in Carloway,
Dalmore and Steinish on the Isle of Lewis in the 1950s
(Fig. 1) (Angus 1993; Cuthbert 1973). Mink then
spread steadily southwards through Harris, and
although attempts were made to stop them from
colonising the Uists [North Uist, Benbecula and South
Uists (Angus 1993)], they were found in North Uist in
the 1990s and a population was discovered in South
Uist in 2002. Thus, they had successfully established
populations across the entire archipelago of 2800 km2
within 50 years of their initial release.
The Outer Hebrides support internationally
important habitats and bird populations. Mink have been
reported to have severe impacts on bird populations
(Clode and MacDonald 2002), in particular on
groundnesting species, and fish populations (Areal and Roy
2006; Bilsby 1999, 2001). In addition to direct impacts
on biodiversity, there are financial concerns in the
Outer Hebrides as eco-tourism, aquaculture, game
fishing and crofting are important elements of the local
economy to the estimated value of up to £30 million
annually (ERM 1996; James 2000).
Methods and results
The Hebridean Mink Project was established with the
objective of removing mink from North Uist,
Benbecula and South Uist and to reduce mink density from
neighbouring South Harris to minimise recolonisation
of the Uists. Descriptions of the project can be found in
Moore et al. (2003) and Roy (2012). The control site in
the Uists comprised approximately 356 islands and
skerries totalling 850 km2. The area contained a
complex mixture of freshwater and saltwater habitats,
with 1116 km of coastline, 2416 km of loch shore and
189 km of rivers and streams, (...truncated)