This semi-aquatic species is a versatile opportunistic predator (2) (4), preying on rabbits (Oryctolagus cuniculus), water voles (Arvicola terrestris), and many other mammals, as well as a range of fish, birds, eggs, crayfish, and a variety of invertebrates (6). This species has had a devastating effect on native species; it has been implicated in the precipitous decline of the water vole, and poses a serious threat to game birds, fish and birds nesting on offshore islands (6). Although it can be active at any time during the 24-hour period, the activity of the American mink tends to peak at night and at dusk (6). They are solitary and territorial, with the male home range overlapping several female ranges (6). Mating occurs once a year, between February and April (6). During this time males leave their territories and increase their range in search of females (2). A single litter of four to seven young is produced between April and May (6). When they reach 13 to 14 weeks of age, the young disperse away from the place of birth (6).