Alien mammals in Europe: updated numbers and trends, and assessment of the effects on biodiversity.

This study provides an updated picture of mammal invasions in Europe, based on detailed analysis of information on introductions occurring from the Neolithic to recent times. The assessment considered all information on species introductions, known extinctions and successful eradication campaigns, to reconstruct a trend of alien mammals' establishment in the region. Through a comparative analysis of the data on introduction, with the information on the impact of alien mammals on native and threatened species of Europe, the present study also provides an objective assessment of the overall impact of mammal introductions on European biodiversity, including information on impact mechanisms. The results of this assessment confirm the constant increase of mammal invasions in Europe, with no indication of a reduction of the rate of introduction. The study also confirms the severe impact of alien mammals, which directly threaten a significant number of native species, including many highly threatened species. The results could help to prioritize species for response, as required by international conventions and obligations.