The window alert decals work well for my bay window, they come in a variety of shapes and are translucent, but reflect uv light so the birds see these and are warned something is in the way of their flight. available in local bird supply shops as well as on-line.? First put up these decals last spring after reading about them on birding list, recently had some boings on window, fortunately birds recovered, so replaced as the uv coating wears off or something. well, should have followed directions and warmed the window with water?before applying when less than 50 degrees out (was mid 40's), most of the decals fell off and some blew away in the strong winds we had last week., anyway?pays to follow the directions in cold weather.