Power line “flappers” prove best deterrent for preventing bird deaths

Researchers at Oregon State University (OSU) College of Agricultural Sciences have found that a bird deterrent called a “flapper” could significantly reduce the number of our feathered friends being killed by colliding with power lines.

One of the major threats to birds is collisions with objects like wind turbines, windows and aircraft, with high-power lines estimated to account for about 170 million killed each year in the United States and a billion worldwide. Not only are the strikes devastating for bird populations, but they can also cause power outages and property damage.

To prevent this from happening, a wide variety of deterrents were developed, including the old-fashioned scarecrows, gas cannons, predator decoys, spinning mirrors, and metallic streamers. For power lines, a common deterrent used for almost 40 years are colorful PVC spirals spread along the cables to provide birds in flight with a clue that there’s a hazard ahead. The problem is, no one is sure how well they work and avian death rates among various species remain much too high.

Conducted in southern Spain, the three-year OSU study compared three kinds of deterrents or diverters: a yellow PVC spiral, an orange PVC spiral, and a 21 x 6.2 cm (8.3 x 2.4 in) spinning flapper made of three orange and red polypropylene blades covered in reflective stickers.

The yellow PVC spiral
The yellow PVC spiral


For the experiment, 13 km (8 mi) of Spanish power lines were marked every 10 m (33 ft) with orange spirals, 10 km (6 mi) with yellow spirals, and another 13 km length with flappers. Meanwhile, 16 km (10 mi) had no markers and served as a control. Every 40 days, the area under the lines was searched for birds and 131 representing 32 species were eventually found.

At the end of the study, the international team found that the flapper had a 70-percent lower kill rate than the control and was significantly better than either of the spirals. OCU says that this is significant because, though the flappers and spirals cost about the same to make, the flappers are faster and easier to install, meaning that there’s less downtime during which the power lines have to be switched off to install the diverters.

“Colored PVC spiral is the most commonly used flight diverter by far, but the flapper diverter was the one showing the largest reduction in mortality with the lowest variation across different power lines, habitats and bird communities,” Morandini says. “We suggest to consider the flapper as the first choice when installing bird flight diverters, recommending to increase future research in testing its material durability and resistance against vibrations and color loss.”

The research was published in Global Ecology and Conservation.

Source: OSU

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