The invasive alien raccoon dog (Nyctereutes procyonoides) proved to be a more frequent and opportunistic predator than any of the native predator species.
Alien species are recognised as presenting an increasingly global threat to native species, but we often lack evidence of their interactions and effects. For example, boreal nesting duck species have recently declined in abundance and in Finland more than half of the species are now classified as endangered. Alien predators have been suspected as playing a part in these declines and new studies suggest that this suspicion is justified. A joint Helsinki and Aarhus University study established more than 400 artificial nests containing farmed mallard (Anas platyrhynchos) eggs in normal duck nesting sites in Finland and Denmark, monitoring nest fates with wildlife cameras.
Invasive American mink pose a risk for birds nesting especially in wetlands & archipelago. It also is a threat for critically endangered European mink.