Just chose between decals and a cheap curtain for my patio door, and the curtain won by a mile
I had two options for the big sliding door in my kitchen: order those dot decals online for about $18, or drive to a shop and get a curtain rod and a sheer panel for roughly $30. I picked the curtain. The decals look fine in photos but birds don't read them the way people think, they just shift an inch or two and smack the gap between dots anyway. The sheer panel changes the whole look of the glass from outside, it kills the reflection of the trees, and that reflection is the real reason birds hit. Had it up since March and we have not had a single thud at that door, and before that it was two or three a month in spring. A friend of mine in Portland swears by the decals and says his work fine, but he also has a covered porch so his glass never shows sky. If your window throws a mirror image of the yard, spend the extra money on fabric, not stickers. Anyone here tried both on the same window and actually kept count?