Variable responses of waterfowl breeding populations to long‐term removal of introduced American mink

Abstract

It is suspected that feral American mink, an introduced predator in Europe, have seriously affected local densities of birds breeding in archipelagos and coastal areas. We studied the effects of mink removal on breeding densities of waterfowl in two manipulation and two control areas in the outer archipelago of SW Finland, Baltic Sea. The study was conducted in two phases: during 1992–2001 a total of 98 mink was removed from 60 islands and islets (total area 72 km2) whereas on 37 islands and islets (35 km2) mink was not removed. Additional mink removal and control areas were established during 1998–2001 to replicate the experiment. The breeding densities of the shelduck, tufted duck and the velvet scoter increased as a response to mink removal, while in the control areas their populations remained unchanged. The breeding densities of mallards increased during the first 7 yr of mink removal, but a steep decrease in the last study year resulted in a statistically non‐significant overall increase. The species with low breeding densities (the gadwall, northern shoveler, pintail and the red‐breasted merganser) increased as well. In contrast, the populations of large waterfowl species, the mute swan, greylag goose, common eider and the goosander, did not show obvious increases in breeding densities after mink removal. We conclude that feral mink may locally limit the breeding densities of some smaller waterfowl species and thus reduce the diversity of the waterfowl community in the outer archipelago.

Mink(Mustela vison)eradication to protect ground‐nesting birds in the Western Isles, Scotland, United Kingdom

“…These include velvet scoter (Melanitta fusca), red-breasted merganser (Mergus serrator), and black guillemot (Andersson 1999). Recent mink control experiments in Baltic Finnish islands have shown how mink removal benefits a wide range of ground-nesting (mainly aquatic) birds, especially smaller species (Nordstrom et al 2002(Nordstrom et al , 2003.…”

An invasive gull displaces native waterbirds to breeding habitats more exposed to native predators

“…Similarly, partially as a consequence of habitat loss, the global waterbird population has decreased by 44 % in the few past years alone (Delany et al 2010) and numerous studies have reported notable declines in waterbirds on a local scale (Crowe et al 2008;Ma et al 2009;Sandilyan et al 2010). However, very little is known about the part played by invasive species in this decline, with the exception of the well-documented role of predatory alien mammals such as, for instance, the American mink Neovison vison (Nordström et al 2002;Brzeziński et al 2012) or the raccoon Procyon lotor (Ellis et al 2007). …”

Voles on small islands: effects of food limitation and alien predation

“…Black adders (Vipera berus) are widespread in Scandinavian archipelagos (Forsman and Lindell 1997) and are regularly observed during summer on all study islands, though not during the autumn trapping before, and the spring trapping after, food supplementation which was carried out on cold days. Additionally, short-and longeared owls (Asio flammeus and A. otus) and Eurasian kestrels (Falco tinnunculus) may exert some predation pressure on voles during spring and autumn migration Nordström et al 2002).…”

“…In the archipelagos of the Baltic Sea, mink have been shown to exert strong predation pressure on voles, sea-birds and amphibians, thus having vast detrimental effects on the biodiversity (Ahola et al 2006;Banks et al 2004Banks et al , 2008Nordström et al 2002;Nordström and Korpimäki 2004). The American mink is a North American mustelid which has continually escaped from Fennoscandian fur farms for more than 60 years and is now widespread throughout semi-aquatic ecosystems in Finland (Kauhala 1996;Niemimaa 1995).…”