Last spring, Justine Kummer was loafing on her couch when she heard a loud bang on the window in front of her. Startled, she ran outside to investigate the noise, and her heart sank as her fears were confirmed: A robin lay dead on the ground, killed by striking her windowpane. Her story is far from unique; window strikes at people’s homes kill at least 150 million birds each year in the U.S. But for Kummer, the robin’s death was more personal. At the time, she was wrapping up the Birds and Windows Project, a University of Alberta citizen science endeavor studying what makes certain homes more dangerous to birds than others. That night, she dutifully filled out the online form she had designed, detailing the location and size of her house, its windows, and any bird-attracting features like feeders or birdbaths. Then she uploaded a photo of the dead robin. “It really hurt,” Kummer says. “I thought I was going to get through the whole project without having to enter...