Nearly 600 million birds are killed each year in North America due to collisions with buildings — and not just skyscrapers. Residences up to four stories in height account for 250 million of the 600 million total, according to the National Audubon Society. Among the major contributors to these deadly crashes: artificial light at night — which disorients the birds — and glass, due to both its transparency and mirrorlike, reflective properties. With the stroke of a pen from Gov. J.B. Pritzker, Illinois became the latest entity to enact legislation aimed at stemming the carnage. Under the Bird Safe Buildings Act, any newly constructed state building will be required to incorporate bird-friendly design. The same rules apply, with a handful of exemptions, to renovations of state buildings in which more than half of the facade is substantially altered.