This is Scientific American's 60-second Science, I'm Jason Goldman.About a billion birds die from flying into buildings each year in North America.Suspicions have been that birds may perceive the open areas behind glass as safe passageways.Or they may mistake the reflected foliage for the real thing.Researchers would like to reduce collisions,which requires a solid understanding about what makes a bird more or less likely to die by smacking into a building in the first place."There was, and still is, relatively little known at a broad scale. Most studies are at one small study site."Jared Elmore, a graduate student in natural resource ecology and management at Oklahoma State University.He and his colleagues used a previously created data set of building collisions for birds at 40 sites throughout Mexico, Canada and the U.S.The first finding was obvious: bigger buildings with more glass kill more birds. But the details were more noteworthy."We found that life history predicted collisions.Migrants, insectivores and woodland-inhabiting species collided more than their counterparts."Most migratory species travel at night, when lights near buildings can distract or disorient them.And Elmore thinks that insect-eating birds might be attracted to buildings because their insect prey is attracted to the lights.He suspects that woodland species get fooled by the reflections of trees and shrubs in the windows.