An invasive predator affects habitat use by native prey: American mink and water vole co‐existence in riparian habitats

This study examines the occurrence of invasive American mink Neovison vison and native water voles Arvicola amphibius along the shorelines of eutrophic lakes and at small midfield ponds in the Mazurian Lakeland, north‐east (NE) Poland. The main hypothesis tested in this study is that built‐up areas and small midfield ponds are avoided by mink; therefore, they can serve as refuges that protect water voles from mink predation. Floating rafts were used to monitor mink and water vole distribution. Mink presence was negatively associated with urbanization at lake shorelines and midfield ponds, and these two characteristics positively correlated with occurrence of water voles in the study area. The probability of occurrence of water voles was significantly lower at sites where mink occurred. The occupancy rates for mink at lakes and at midfield ponds were higher in autumn than in spring and conversely the occupancy rates for water voles were higher in spring and lower in autumn. Our study shows that within a postglacial landscape, urban areas and midfield ponds distant from lakes are avoided by the American mink and thus these areas may function as refuge habitats for water voles and may maintain populations of this rodent at the landscape scale despite the presence of mink. This study showed clear spatial segregation between the invasive American mink and water vole. Built‐up areas and midfield ponds distant from lakes are avoided by the American mink and thus they may function as refuge habitats for water voles. Mink predation may explain the high tolerance of water voles to riparian habitats adjoining human settlements, which was documented for the first time in our study.