The relationship between the grid and the surrounding environment and the impact of the former on biodiversity differs according to whether the stage in question is that of construction or of operation. In the construction stage, the impact on biodiversity is connected with the worksite. The construction of lines1 and stations requires particular care if it takes place near or inside protected areas. 

Once the line has been constructed, it has a two-fold relationship with the environment. On the one hand, its route may increase biodiversity and protect some species. When lines cross large open areas or extensive areas of grain monoculture, for example, the pylons and their bases constitute “islands” of concentrated biodiversity. Pylon bases, especially larger ones which support high-voltage lines, are the only places spared by the intensive agriculture and its intensive working and transformation of the land. These are the places where spontaneous grasses and brambles grow, in which wild rodents take refuge, because their den systems are not destroyed periodically by ploughing. They are also the places where predators of the rodents, birds of prey, congregate. In effect, birds, especially those of prey, commonly use electric lines and their pylons for both observing the surroundings and nesting.   

On the other hand, the lines have potentially negative effects on biodiversity, which regard birds in particular. Terna’s infrastructure does not present any risk of electrocution, which is connected with the narrow space between the conductors that characterises low- and medium-voltage lines[1] and can lead to the electrocution of birds – especially large ones – flying through them. High-voltage lines, instead, create the risk of collision. Actual collisions depend on the density of the birdlife and the frequency with which the birds fly near the lines. The most important factors are the routes of migratory birds – particularly important in Italy, which constitutes a bridge between Europe and Africa – the location of wetlands in the area, and the presence of protected areas, sanctuaries, and parks.  

 Type of bird of prey


1 Given the wingspan of the bird species, in Italy high-voltage lines are not normally considered to be a risk for electrocution, which, instead, has been identified as the most important cause of death for accidents involving birds on low- and medium-voltage lines. The most important scientific study is still V. Penteriani, “L’impatto delle linee elettriche sull’avifauna”, WWF Italia, Serie Scientifica no. 4, 1998.