A framework for prioritising present and potentially invasive mammal species for a national list

The European Union (EU) has recently adopted a regulation on invasive alien species that foresees the possibility of developing lists of species of National Concern. We developed a prioritisation process for alien mammals already established in Italy, but not yet included in the EU list (n = 6 species) and a systematic horizon-scanning procedure to obtain ranked lists for those species that are already introduced worldwide or traded in Italy (n = 213). Experts were asked to score these species, by evaluating their likelihood of establishment and spread and the magnitude of their potential impacts on biodiversity, economy, human-health and society. The manageability of each species was also evaluated, both for the proritisation and the horizon-scanning processes. We produced five lists that ranked species according to their potential spread and impacts and their manageability. These will allow policy-makers to select outputs according to a balance between risk assessment and risk management, establishing priorities for alien species management at the national level.