We've got these huge windows on the back of our house, and every day at least one bird slams into them. Some of them die, some are stunned and have to sit awhile before they can fly away, and others just seem to bounce off and keep going. We have tried putting reflective stuff on the windows, but it doesn't help. We have a bunch of these marks on the windows which even show the wings and feathers as they hit. These windows are hard to reach so they don't get cleaned real often. So the tally of bird vs. window continues to climb.