A Bird's Eye View window strike films are easy to install and inexpensive, as well as lovely. (I had used bird silhouettes in the past and was not impressed.) I purchased clear designs in both 6 " and 4" and see what happened.
I am delighted to report that we have not witnessed a bird strike since I put these on our windows four months ago-and we have been home the WHOLE time.
If you are looking for a lovely alternative to screens-that works-I highly recommend the ArtScape Bird's Eye View squares.
below: close up of one of the 4" designs