No country for native crayfish: importance of crustaceans in the diet of native and alien Northern raccoons

The Northern raccoon Procyon lotor is a native mesocarnivore of NorthAmerica which has been introduced to many Eurasian countries, where invasivepopulations currently occur. Regarding Italy, the species is present in Lombardyand in the Foreste Casentinesi National Park (Tuscany and Emilia-Romagna). Inthis work, we conducted a review on food habits of the Northern raccoon both inthe native and in the introduced ranges, and we firstly reported the evidence onthe impact of this species on native crayfish in Central Italy. We retrieved 18papers published between 1932 and 2020, 14 from the native range and four fromthe invasive range. We analysed the frequency of occurrence of nine food categories(mammals, birds, reptiles, amphibians, fish, insects, crustaceans, fruits,and others). After fruits, crustaceans (where available) were the main food itemsdetected in raccoon scats (up to 60% of the total diet, in the frequency ofoccurrence). In September 2019, we detected a total of 37 dead adult freshwaterwhite-clawed crayfish Austropotamobius pallipes complex in Central Italy, withevident signs of predation by the Northern raccoon. The local population ofNorthern raccoon is fast expanding its range, whereas the local population ofA. pallipes complex is declining. This crayfish species is protected by national andinternational laws. Thus, a monitoring program involving all stakeholders andinstitutions dealing with in environmental management, aiming at removing allraccoons currently present in this area of Central Italy, should be carried out inthe short term to limit the potential impacts exerted by the fast-spreading of this invasive mammal.