Biodiversità degli Ardeidi lungo un gradiente di urbanizzazione nel territorio della Città Metropolitana di Torino

The territory of the ¿Città Metropolitana¿ of Torino represents an important site for the migration routes and for the breeding of the Ardeidae, which in recent decades have gone to occupy the urban areas of the city. The continuous fragmentation of natural habitats and the overbuilding that reduce the presence of wetlands and arboreal vegetation - both necessary conditions for the survival of these species - have led to the use of urban fringes, as well as private parks, as nesting sites. From the analysis of five heronries located on the territory of the ¿Città Metropolitana¿ of Torino emerges an inversely proportional relationship between biodiversity and urbanization. In heronries located in a more urbanized environment, are mainly observed the overwintering of Gray herons and the summery visiting and/or transient migrations of a few other species (such as Little Egret, Cattle Egret and Great Egret). Moving towards more rural areas, where urbanization has less impacted, or towards areas included still in the urban context but protected and designated as SPAs (e.g. the heronries of Isolone Bertolla and of Lake Candia), we can find an increase in the biodiversity botch of the gregarious Ardeidae (including Red Heron, Night Heron, Little Egret) and of the not gregarious ones (Bittern and Little Bittern).