We have one or two windows that, in the past, birds have flown into and died. We had solved the problem by sticking a few rectangles of paper to the inside of the panes, which did the trick, but they looked pretty untidy. I have just found this site on which you can download and print out black silhouettes of birds of prey. To give a good contrast to bird silhouette, I have left a 1/2" border all round, the white of the paper makes the bird stand out. The site is -
http://songbirdphoto.com/wordpress/?p=136