2024

"Collisions with power lines affect birds worldwide, including countries such as Belgium where a
nationwide model indicated high avian collision risk in the IJzerbroeken region (seasonally
flooded riverside wetlands). Large numbers of waterbirds winter in this area, which is crossed by
a 70-kV transmission line. To manage avian collision risk, the transmission system operator,
Elia, installed AB Hammarprodukter’s FireFly™ FF line markers incorporating reflective, glow-
in-the-dark, high contrast, and moving elements intended to increase the visibility of the
transmission line to flying birds. We evaluated the effectiveness of FireFly line markers by
comparing the numbers of avian carcasses found during 11 surveys annually in 2001 and 2018
(22 total surveys) before line markers were installed compared with 11 surveys conducted
in 2021 after line marking. Before line marking, we found 30 avian carcasses attributable to
collision in 2001 and 113 in 2018. After, we found six carcasses attributable to collision in 2021.
In 2021, FireFly line markers correlated with a reduction in collision rate, depending on the pre-
treatment year and species group, of at least 85% and up to 100%. The line was composed of two
configurations, with half of the spans (two-thirds of the monitored line length) supported by tall
pylons with shield wires, and half of the spans supported by shorter pylons without shield wires.
After line marking, six collisions (100% in 2021) occurred on spans supported by tall pylons, and
none (0%) occurred on spans supported by short pylons. Thus, in 2021, FireFly line markers
correlated with an observed mortality reduction of at least 73% and up to 100%, depending on
the configuration being considered. These findings suggest FireFly line markers substantially
reduced wintering bird collisions in our study area."