PowerLines4Birds - How are we making power lines safer for birds?

Fireflies

The LIFE PowerLines4Birds project is an Iberian partnership between SPEA, Quercus, LPN, SEO, and E-REDES with the aim of mitigating the risk of mortality on power lines for seven endangered bird species. To this end, measures are being implemented to mitigate the risk of electrocution and collision. The aim is also to evaluate the effectiveness of innovative measures to simultaneously mitigate these two risks. In this series of news, we want to present the various mitigation measures being applied in the LIFE PowerLines4Birds project to safeguard birdlife. These include measures such as the Combined Solution to reduce the risk of electrocution, Firefly Bird Flappers (FBF) to reduce the risk of collision, eco-crossbar, and the burying of power lines to reduce both risks simultaneously.

Birds often benefit from energy transport structures, particularly pylons, for nesting, resting, or as hunting perches, as well as from power lines for resting and perching. However, these structures pose a substantial risk of electrocution and collision for birds. This issue raises significant conservation concerns, especially in a context where the electricity grid is rapidly expanding globally. In addition to the direct impact on birdlife, these occurrences can pose constraints for energy distribution companies due to service interruptions and the increased risk of fires.

Bird mortality on power lines: Electrocution and Collision

Electrocution occurs when birds use supports and simultaneously touch two phases of the power line or one phase of the power line and an element connected to the ground. It is more common in large species with a greater wingspan, such as storks (Ciconia ciconia), griffon vultures (Gyps fulvus), black vultures (Aegypius monachus), and Iberian imperial eagles (Aquila adalberti). Collision, on the other hand, occurs when a bird fails to perceive the overhead cable as an obstacle and crashes into the line as it approaches. The great bustard (Otis tarda), the heaviest flying bird in Europe, is a well-known example of a species vulnerable to collisions with power lines. Its speed, combined with its difficulty in maneuvering in flight and limited forward vision, makes it particularly prone to fatal collisions with power lines.  Both the risk of collision and electrocution are influenced by several factors, including the characteristics of the species itself (e.g., vision, morphology, phenology, behavior, circadian cycles, age, sex, and health status), site conditions (e.g., topography, weather conditions, habitat, and human disturbance), and factors specific to the power line (e.g., the arrangement of electrical cables on the supports).

Collision mitigation

The most commonly used measure to mitigate the risk of bird collisions with power lines is the installation of devices that increase the visibility of the lines to birds in flight.

The first devices began to be installed on the electricity distribution network in mainland Portugal very early on, and have continued to evolve to this day. Over the years, many different models of markers have been developed, which can vary in size, color, material, and function. They can be fixed or mobile, and also vary in installation methods and technical specifications. Some examples include single spirals, double spirals, Firefly Bird Flappers (FBF), better known as Fireflies, among others (Figure 1).

Figure 1 - Examples of power line markers used in electrical distribution networks: a) Raptor Clamp markers; b) Single spirals; c) Double spirals; d) Fireflies, tape type (left) and rotating type (right)

In general, to effectively mark a power line, markers must be detectable by a bird at a distance that allows it to avoid collision by changing its trajectory. Therefore, it is essential that the marker is visible in various weather and light conditions, and that it is designed with birds' vision in mind. For this reason, combinations of black and white or reflective and photoluminescent markers, with rotating or oscillating movement caused by the wind, are often recommended. The dimensions of the devices must also take into account the visual capacity of birds, however, as a general rule, the larger the marker, the greater the likelihood of it being detected. In any case, technical constraints must also be considered so that they can be safely applied to the power line. Another factor to consider is the durability of the materials, especially in adverse conditions, so that the equipment has a long life with little maintenance. Finally, the spacing between markers is an important factor, as the smaller the interval, the greater the likelihood of making the line visible to an approaching bird. For this reason, a spacing of 5 meters is often recommended on medium-voltage power lines in areas of greater risk.

Devices installed in the Project: Firefly Bird Flappers (FBF)

In order to mitigate the risk of birds colliding with power lines, two highly effective types of Firefly Bird Flappers (FBF) are being installed on medium and high voltage lines: ribbon type (Figure 2) and rotating type (Figure 3). The installation of these devices will cover 91 km of power lines identified as priority in 14 Special Protection Areas (SPAs) in Portugal.

Figure 2 - Left: Tape-type Firefly (1) Elastomer clip for attachment to electrical cable; (2) Neoprene tapes; (3) Aluminum plates; (4) Photoluminescent and retroreflective plates; (5) Stainless steel screws; Right: Tape-type Fireflies installed on a power line.

Both types of markers are more successful in reducing the risk of bird collisions when compared to single and double spirals, and although both rely on movement, rotating fireflies are distinguished by the fact that they spin around in the wind, which increases their visibility and effectiveness. In addition, ribbon-type and rotating FBFs have reflective and photoluminescent plates which, in the case of rotating ones, can produce a sparkling effect visible to birds from up to 450 meters away.

Figure 3 - Left: Rotary-type firefly; Right: Rotary fireflies installed on a power line.

Previous projects have shown that rotating fireflies are more effective for steppe bird species such as the bustard and the little bustard. This information is relevant when the LIFE PowerLines4Birds team identifies and proposes power lines for correction with collision mitigation measures in pseudo-steppe cereal regions.

Between 2023 and 2025, of the 91 km of lines proposed, around 50 km of medium and high-voltage power lines have already been marked with both types of devices.

Next time you pass by power lines, keep an eye out. You may be able to spot some of these devices.

About the project LIFE PowerLines4Birds