Monitoring of effectiveness of bird flight diverters in preventing bird mortality from powerline collisions in Slovakia

Abstract

Flight observations and carcass searches were carried out along distribution power lines in Slovakia. 77 km of 22 kV and 110 kV lines were marked on a total of 108 sections to evaluate the effectiveness of three types of bird flight diverters (FireFly Bird Diverter, RIBE Bird Flight Diverter and SWAN-FLIGHT Diverter) designed to increase power line visibility. Numbers of carcasses were compared before and after installation of the devices and reaction distances on marked power lines were surveyed. We observed a 93.5% reduction (93 vs. 6) in the number of fatalities under the marked power lines after line marking (06/2016–06/2019) compared to the period before installation (12/2014–02/2016). 2,296 flight reactions were observed and an estimated total of 41,885 individuals (57 bird species belonging to 13 orders) were recorded with their reactions to marked lines in the period 06/2016–06/2019. After installation of bird diverters, there was a low proportion of flight distance observations at the closest distance, i.e. up to 5 m, indicating that birds reacted further away from marked lines. Although we lack flight observations for the period before the installation of diverters, the reactions of birds at greater distances and reduced number of bird victims under marked lines indicate that all tested diverters have a positive effect on reducing the number of avian collisions with power lines.

Flight altitudes of a soaring bird suggest landfill sites as power line collision hotspots

“…Even so, at that distance, because storks fly at an average speed of 10m/s when close to the reaction distance (80-150m), they only have 8s to change flight altitude and avoid collision, a short period considering their size.. Due to their low in-flight manoeuvrability, white storks' capacity to adjust paths to avoid power lines is very limited and primarily constrained by thermal uplift conditions, cloud cover and in specific circumstances of low sunlight, visibility, and high densities of lines. Previous studies showed observed in-field birds reaction to power lines beyond 25m (Brown and Drewien, 1995;Gális and Ševčík, 2019;Murphy et al, 2016a). To our knowledge, this is the first time we estimate a specific value of reaction distance of white storks to power lines.…”