Urban mammals in Italy: how common species shape communities’ differentiation

Urban areas, and the share of population inhabiting them, are rapidly expanding, with significant impacts on biodiversity. Nevertheless, multi-city comparative studies on urban wildlife –specifically mammal communities – remain scarce, particularly in Italy. Thus, we investigated how a standard evaluation of green cover and fragmentation, designed for a national biodiversity monitoring program, and regional context shape medium-and large-sized mammal assemblages in four Italian cities in Northern, Central, and Southern Italy (Milan, Rome, Florence, Campobasso). We deployed a total 48 camera traps across 1 km² grid cells covering two gradients of green cover and fragmentation. We accumulated 8,759 trapping days and 17,996 independent detections of 12 wild species. Species’ detections were generally consistent with their known national distribution, except for the unexpected occurrence of wild boar and wolf in Milan. Contrary to expectations, we found no significant effects of green areas extent or fragmentation on community composition, suggesting that alternative metrics or spatial scales may be more appropriate for capturing urban mammals’ distribution patterns. Nevertheless, our results revealed significant differences in community composition among cities (PERMANOVA, p=6e-04), with Milan showing the most distinct assemblage compared with Florence, Rome, and Campobasso. The Random Forest analysis identified the red fox (Vulpes vulpes) and the eastern cottontail rabbit (Sylvilagus floridanus) as the most influential species driving inter-city differences, followed by the wild boar (Sus scrofa), crested porcupine (Hystrix cristata), martens (Martes spp.), and the European hedgehog (Erinaceus europaeus). Overall, this work provides a baseline for further investigations of urban mammal ecology in Italy.