Lines and birdlife


EN14Lines have potentially negative effects on birdlife. While the risk of electrocution characterizes low- and medium-voltage lines, Terna’s high-voltage lines can be dangerous particularly for the risk of collision. This is why on stretches of line characterized by the frequent presence of birds in transit, the Company has installed special devices called “dissuaders”, which, with their encumbrance and the noise made when they are blown by the wind, make the lines easier to perceive by the birds in flight.

  2011 2010 2009
No. of lines concerned 40 37 30
No. of lines concerned 171 159 146
Total No. of dissuaders 9,116 8,917 8,845

Criteria for location of dissuaders in the planning phase: the Trino-Lacchiarella power lineEN14

In 2011, work began on the construction of the 380 kV Trino- Lacchiarella line. 70% of the line will be built with low environmental impact supports. This solution was decided on taking into consideration the context of the landscape being crossed, as the more harmonic shape of a single pole minimizes the visual impact of the future line.

In compliance with the requests of the Technical Commission for the Environmental Impact Assessment EIA-SEA, the Region of Piedmont and the Ministry for Cultural Heritage and Activities, Terna investigated the technical feasibility of placing dissuaders in order to mitigate the potential impact of the power line on birdlife.

With the aid of the scientific contribution of the Animal Biology Department of the University of Pavia, Terna identified the segments of the power line that should be made more visible with the installation of spirals. An analysis also indicated that only the guard wires needed to be made more visible, whereas the conductors, having three circuits, (i.e. there will be three cables for each phase), are easily seen and recognized by birds, and do not pose a threat.

Once the segment was identified, and the need to place dissuaders only on guard wires was assessed, the structure of the planned supports was verified, taking into account the installation of the spirals on the guard wire with a center distance of not less than 25 meters. This distance is based on the most cautious indications for birdlife recommended by the Department of Animal Biology of the University of Pavia.


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

The project represented an important opportunity to systematically study for the first time, and on a large national scale, the actual interactions of birdlife with the high- and extra-high-voltage lines of the National Transmission Grid (NTG). The only studies available regarded the phenomenon of the electrocution of birds whose wings touch two wires at the same time, which is typical of low- and medium-voltages lines.

LIPU’s study highlighted that collision risk for birds with HV and EHV electricity lines is low in 4 out 7 areas monitored. Near the lake in Montepulciano and in the Mezzano area – which are wet areas subject to migratory flows – increased risks seem to exist for birds, suggesting additional observations also with new experimental approaches, for a correct risk assessment and identification of possible mitigation measures. The study conducted on the Strait of Messina stressed the need of a more detailed monitoring with the aid of appropriate technology, such as the use of radar.

For some time Terna has been involved in experimenting with alternative uses of electricity lines to benefit biodiversity. Worthy of particular mention is the placement of nest boxes for predatory birds atop the pylons. Numerous studies have indicated that electricity lines function as observation points for predatory birds on the hunt, who perch on the supports due to the height and protection they offer from predators.

In 2011, Terna continued its support to the “nests on pylons” initiative in collaboration with the ornithological association Ornis italica, which, through the years, has resulted in the installation of nearly 500 boxes suitable for bird nesting. The constant monitoring of the boxes by a group of researchers has allowed for the collection of biological and ethological data, and has shown a positive effect in terms of biodiversity. Among the main species that have occupied the boxes is the kestrel, a species of small falcons that have adapted to living in manmade areas, the horned owl, and the European roller.

Also in the 2011 reproductive season, the boxes on the pylons were monitored to collect data on reproduction (see the following box).

In 2011, Terna continued its collaboration with Ornis Italica with the Birdcam Project, which entailed installing cameras in artificial nests so that the reproductive period of the birds could be followed online at, as well as on Terna’s website. The webcam connection also allows for the remote scientific observation of animal behavior by researchers.

The 2011 reproductive season in the nests on Terna’s pylons

Nidi su tracciati Terna

Kestrels, cuckoo falcons, peregrine falcons, horned owls and European rollers are the species of birds that have chosen to spend their reproductive seasons in the artificial nests on Terna’s high voltage pylons.

The monitoring of artificial nests was carried out by Ornis italica's ornithologists, who, in 2011, inspected nearly 10% of the over 500 nests placed on the grid's pylons in Lazio, Tuscany, Umbria and Emilia-Romagna.

In the Parma area, 31 kestrel nests were monitored and 99 chicks were ringed. For the first time, a nest with a pair of cuckoo falcons was spotted with three chicks, all of which were ringed two weeks after birth. The nature of colonial falcons to reuse old nests lends hope that in 2012 this first couple and their chicks will return to settle more permanently in the area. The other new nests which were created to foster the reproduction of this medium/small-sized migratory falcon were, instead, occupied by kestrels. In the same area there was no evidence of European rollers or horned owls in the nests.

Also nests in the Mazzano area, in the province of Ferrara, which were installed for the cuckoo falcons, were occupied instead by kestrels. Completely unexpected, on the other hand, was the presence of bats (the Lesser Noctule) in daytime rest in a very tight space between a nest wall and the pylon support.

Two nests located in the Ferrara area hosted pairs of European rollers, from which 8 chicks flew away: considering the rareness of the species in this area, the occupation of the nests is an important success, perhaps the beginning of a greater future colonization.

In Lazio, nearly 60 nest boxes intended for European rollers and horned owls have been monitored. With respect to 2010, the presence of pairs of European rollers has almost doubled (there were 15 in 2010, and 25 in 2011) and the number of horned owls has also increased. In all, 98 European rollers and 12 horned owls were born, the majority of which were ringed. No monitoring of the reproduction of kestrels took place in 2011.

In some cases, the nest box is outfitted with a webcam that provides the scientific community 24/7 – as well as enthusiasts - with round-the-clock viewing of all phases of reproduction, from the laying of the egg to its hatching and up to the moment the chicks spread their wings to fly away.

The adoption of new technology for the audio and visual transmission in HD has further improved the quality of the streaming. An “eggcam” was tested, which allowed for close-up shots of the egg being laid and, subsequently, cracking open. These novelties broadened the vast audience of enthusiasts: the first posting on YouTubeshowing an egg being laid was uploaded by an American birdwatcher.