Bird strikes—the collision between birds and aircraft—are among the most common aviation hazards. They destroy planes, kill people, and, in the United States alone, cause an estimated $700 million in damage each year. One possible approach to reducing collisions lies in outfitting planes with warning lights that would help birds notice their approach and avoid a collision, but the differences between human and avian sight—which include a wider color space and higher sensitivity to ultraviolet light in birds—make developing such solutions complicated. Now, researchers have found that blue LED lights (with a wavelength of 470 nm) are the most conspicuous to brown-headed cowbirds, which often collide with aircraft. The scientists fitted lights of this color to a small, remote-controlled model airplane. They then recorded the reactions of cowbirds in cages to this plane—both when stationary and when flying toward the birds—with the lights on, off, and pulsing. The researchers found that having the lights on made the cowbirds five times more likely to exhibit an alert response (such as stretching their necks, raising their heads, or crouching) to the stationary plane than without; the birds were also twice as quick to respond to planes with lights than to planes without lights. Similarly, although the time the birds took to react to the moving plane got slower as the plane’s speed increased, the presence of flashing lights helped the birds react faster than to those without. Based on their results, reported in The Condor, the researchers propose a number of preliminary concepts that could help birds better avoid aircraft—such as runway lights that illuminate in sync with taxiing planes and onboard lights that flash during taxiing and shine continuously during takeoff. Similar approaches could be adapted for stationary obstacles, too—such as skyscrapers or wind turbines—to help reduce collisions.