STORRS, CT—Shedding considerable light on a previously mystifying aspect of accidental avian death, a new study from the University of Connecticut has found that direct frontal impacts with clouds kill over 5 million birds every year. “Our observations, some of them quite harrowing, demonstrate that controlled, full-speed flight into a cloud is one of the leading causes of death among birds across nearly all species and spanning every continent on Earth,” said head researcher Rebecca Levin, explaining that bird eyesight has not evolved to perceive large masses of water droplets or ice crystals suspended in the atmosphere, leading birds to mistakenly believe their course is completely clear when in fact, dangerous, rock-hard clouds are directly in their flight path. “Conversely, many birds with extraordinary vision, such as eagles and hawks, seem to think they can fly right through clouds, shattering their spines almost immediately. The problem is probably made worse by the fact that many clouds seem so soft and fluffy.” Levin and her team hope that their study of bird deaths will help scientists understand why half of airline flights crash every year.