Rapid expansion of the American mink poses a serious threat to the European mink in Spain

The American mink (Neovison vison) was introduced in Europe for fur farming in the 1920s and feral populations were formed due to escapes or intentional releases to the wild thereafter. Nowadays, the species is widely distributed across much of the continent, and is considered the main cause of extinction of the European mink (Mustela lutreola). In Spain, the first populations of the American mink were formed in the 1980s and since then a continuous expansion in their range has been observed. We describe the expansion process of the American mink based on reports of its distribution in the literature, focusing particularly on its increasing overlap with the distribution of the native, endangered European mink. Over the 27 years (1985–2012), the distribution area of non-native mink in Spain increased by 17 times, with an average annual increment of 16.5% and no significant variation among populations. By 2012, a quarter of continental Spain was occupied by the American mink and its presence was confirmed in one-third of the distribution area of the European mink. The status of native mink has worsened drastically in Spain over the last years and urgent conservation measures are required to stop further spread of the American mink.