Despite their exceptional visual acuity, raptors – birds of prey – do not detect some obstacles like glazed surfaces, or are too late in detecting certain moving objects, like airplanes. In France, over 800 collisions of birds with planes are reported annually in France, where researchers have The deterrent pattern on display at Lourdes-Tarbes-Pyrénées. Source: Anthony Boigné, Université de Rennesdeveloped a new means of repelling these birds from specific areas.

In analyzing how captive raptors reacted to a series of visual stimuli, the scientists determined that one pattern triggered avoidance behavior by means of an optical illusion. The design consists of concentric black circles on a white background, creating a so-called "looming" effect, giving the birds the impression of an imminent collision.

The pattern was tested at Lourdes-Tarbes-Pyrénées Airport, near an area where raptors forage in the summer. It was displayed continuously throughout the day on two LED screens positioned in strategic locations, while a total of 8,800 observations were made at points all over the airport zone. Rapid modification of the birds' distribution was observed -- they stayed clear of areas from which the screens were visible. This avoidance behavior was still observable after five weeks of continuous pattern display.

The raptor population increased in places where the displays were out of view, and at a time when their food supply was nonetheless abundant in all areas -- confirming the pattern's efficacy. Scientists from CNRS and Université de Rennes developed this sustainable solution for repelling raptors from high-risk areas. The research is published in PLOS ONE.