Invasive predators and the conservation of island birds: the case of American Mink Mustela vison and terns Sterna spp. in the Western Isles, Scotland

摘要

Capsule Colonies were larger and breeding success lower in mink-inhabited areas. Aims To examine the impact of mink on dense aggregations of ground-breeding seabirds on islands previously isolated from mammalian predators. Methods We compare 1990-93 tern breeding data with records before and after mink arrival. Results In the early 1990s, terns showed no preference for mink-free islands. The breeding behaviour and success of tern colonies in mink-inhabited areas did not significantly differ from that in mink-free areas. However, colonies were larger and breeding success lower in mink-inhabited areas compared to mink-free areas, trends which might reflect longer term mink impact. Conclusions As mink spread south there seems to be a gradual increase in tern colony size affecting Lewis, then Harris and, recently, the Sound of Harris.