Birds may continue to fly towards the window, but they will bounce off the mesh unhurt. Hang hawk silhouettes. Attach hawk silhouettes to the window's surface. The silhouettes are most effective if used in multiples. It is helpful also to attach the silhouettes by a suction cup or a hanging device from the outside so that movement caused by wind will catch the birds' attention.
Most people think that the graceful shapes are interesting rather than unsightly.
They're available commercially but they're also easy to make. Be sure to place several on any large expanse of glass. If this presents a problem, hang the silhouette from the sash around the window. Not only can you make your house safer for birds, but by making several silhouettes and giving them as gifts to friends, neighbors, and even that office building with the big glass windows down the street, you can also encourage others to make their houses bird-safe.