Bird-Friendly Window Dimensions

FWS standards for bird-safe glass: external (i.e., on exterior side of glass) visual barrier/markers spaced no more than 2 inches vertically, 2 inches horizontally, or in a 2-inch by 2-inch form. This can include bird-safe retrofits or inherently bird-safe materials such as external insect screens, etched/fritted/frosted glass, external shutters, or absence of glass (i.e., building has no/too few windows).