Biodiversity

Sorgente - Rizziconi line: monitoring of migratory flows of birdlife for optimal planning of decommissioning 

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Last year we published news of the experimental use of radar to monitor the passage of birdlife near the Strait of Messina, an area heavily crossed by migratory routes. The study made it possible to exclude significant risks for birds in the area where the Sorgente – Rizziconi line is planned to pass.

In 2012 Terna again monitored the passage of birdlife between Calabria and Sicily, within the “Nature Network 2000” areas, to obtain useful indications for planning the decommissioning of the old lines currently present in these areas, as prescribed by the Environmental Compatibility Decree for the Sorgente – Rizziconi line.

This second monitoring was of a traditional type, i.e. with observers on the ground, and was conducted 24 hours a day at the time of the spring migration of birds, from the middle of April to the middle of May 2012.

10,130 birds were counted in Sicily and 28,776 in Calabria.

The data recorded confirmed the low migratory flow in the area affected by the Terna power line both in the more easterly Peloritani zones and in the area of Aspromonte, showing that the zone in which the new power line is planned to pass is little involved in the birds' migration, particular birds of prey, which cross further to the South-East or along the Ionic coast, depending on the wind direction.

Most crossings are far from the future line, while those closer are at a height of more than 100 metres, a height which leads us to believe that the future line will not interfere with migration.

These positive results are currently being studied by the planning offices to define the technical aspects of future decommissioning.

 

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Terna's grid is spread out all over the country. The interaction of the grid with the surrounding natural environment and its impact on biodiversity take on different features during construction of new lines and operation of existing lines. In the construction stage the impact on biodiversity is associated with site work: opening of passages to arrive and erecting pylons, excavating the ground, removing residual materials. The work of constructing new lines and stations requires particular attention if it occurs near to or in protected areas. 

Once the line has been built, the relationship with biodiversity is two-fold. On the one hand, the route of the line may be a factor in increasing biodiversity and the protection of certain species. For example, when lines cross vast open areas or large areas with cereal monocultures, pylons and their bases constitute “islands” of biodiversity concentration. The bases of pylons, above all the largest ones, carrying High Voltage lines, are the only zones saved from intensive agriculture and subtracted from the activity of working and transforming the land. These are areas in which wild herbs and thorn bushes flourish and in them wild rodents take refuge because their den systems are not regularly destroyed by ploughing activities. They are also those around which birds of prey, which are the predators of these rodents, are concentrated. In fact, birds, and in particular birds of prey, often use power lines and pylons both as points from which to observe the territory and as nesting structures.

On the other hand, the presence of lines has potentially negative effects on biodiversity, which concern birds in particular. The risk of electrocution is not a concern for Terna's plants, because it is present only in the small space between the conductors typical of low- and medium-voltage lines, which can cause birds – above all large ones – to be electrocuted if they cross the route. The presence of High-Voltage lines is associated instead with the risk of collision. The actual occurrence of collisions depends on the density of birdlife and on the frequency of transits in flight near the lines. The significant factors in this sense are the routes of migratory birds – particularly important in Italy which is a “bridge” country from Europe to Africa – the location of wetlands around the country, and the presence of protected areas, reserves and parks.

In 2008 Terna signed an agreement with the LIPU (the Italian partner of Birdlife International) for a scientific study on the interaction between High-Voltage lines and birds.

The project was an important opportunity to study, for the first time in a systematic way and on a large national scale, the real interactions of birdlife with High- and Extra High-Voltage power lines of the National Electricity Transmission Grid (NTG). The only studies already available involved death by electrocution of birds that touch two wires at the same time with their two wings, typical of low- and medium-voltage grids.

The LIPU study, which was completed at the end of 2011, showed that the risk of birds colliding with High- and Extra High-Voltage electricity lines is modest in 4 of the 7 areas monitored. Near Lake Montepulciano and in the area of Mezzano – wetlands subject to migratory flows – there seem to be more risks for birdlife which require supplementary observations, also using new experimental approaches, to correctly assess the risk and identify possible mitigation measures. In the study carried out on the Strait of Messina, the need emerged for more detailed monitoring with the aid of appropriate technology, such as radar.