Prevent birds from hitting your window

I had a robin attacking a window. Robins are territorial in spring. This seems to have kept him away. The silhouettes need to be moved routinely to be effective.

PeregrineCut-out_YG.jpg (JPEG Image, 2490x3192 pixels)
http://environmentyukon.gov.yk.ca/mapspublications/images/PeregrineCut-out_YG.jpg