The occurrence of wild-living American Mink Neovison vison in Transylvania, Romania

American Mink Neovison vison is a common wild-living alien species across most of northern Europe, but few data are available about wild presence in Eastern Europe. Field observations and collected specimens from the last 25 years indicate wild-living American Mink along the River Mureș in Transylvania, Romania. These are likely to have originated from fur farms, three of which existed in the area. Earlier observations suggested only the presence of escapees; more recent records might imply the existence of wild populations. Part of the study area held European Mink Mustela lutreola until at least the 1990s. This highly threatened species might still occur there. The presence of the alien species might reduce its chances of survival.