2020

Overhead lines can have a high risk potential for birds. During flight, birds can collide with the structure, as the conductors and especially the earth wires are often difficult to see. The collision may lead to death or injury. To study the influence of overhead lines on the avifauna, a video monitoring system was installed on the line in the autumn of 2017. The idea behind this project is to gain a complete overview of how many individuals are present in the area surrounding a line section or cross the line within a defined period. On the basis of these data, one can obtain findings on the collision rate compared to the overall bird population. Furthermore, insights on the manner in which birds cross the overhead line can be acquired by analysing the video recordings.

The study was conducted from 11/2017 to 12/2018. The monitoring system consists of a camera system installed on the corner post of a tower at about nine metres height, as well as a solar panel for the power supply and a data storage unit. The research corridor covers a 400 metre long span. The monitoring system traced the flight movements of birds in a perimeter of approx. 100 metres around the conductors of the observed span. The system is equipped with a sensor system, so that images are only captured when birds are actually present near the line. The registered video sequences were then analysed by ornithologists. The number of sequences to be analysed exceeded expectations: 571 per month on average. The explanation for this large bird population is the location of the observation area in the Unteres Odertal national park, directly on the west bank of the Oder river. The area is an SPA in accordance with the EU Directive 2009/147/EC (Birds Directive). The choice of the observation area was made together with the regional ornithological station and the nature conservation authority.

During the one-year period (Dec 2017 - Dec 2018), 4,822 line crossings by individuals or flocks could be observed based on the video recordings. The 4,822 analysed power line crossings involved 107,143 birds. Nearly 60 % could be identified at species level. Nearly all individuals could be identified at order, family or genus level. The result showed that approx. half (45 %) of the individuals crossing the lines fly over the line. Approx. one quarter cross the line between the earth wires or conductors, and another quarter cross below the line. Of the 4,822 observed power line crossings by individuals or flocks, five collisions with the power line could be documented. This leads to a collision rate of 0.1 %. The colliding birds could be identified at the species level. Mainly concerned are large birds (geese, mute swans). For these birds, a higher collision rate must therefore be recorded.