That's true, so closely spaced markings are recommended. I had the same problem and this dotted tape solved it completely. Personally, I didn't want clip art graphics on my windows, and I like the fact that the dotted tape minimizes interference with my view outside. You can find more information on other strategies here though (like drawing deterrent patterns with bar soap).
*Two inch spacing worked for me, but you might need to make it denser depending on the species you're accidentally luring
This happened to my Dad when he retired from the military. The DC area offers some high-paying jobs for military retirees, but the whiplash for some is soul-crushing. I am encouraging my other family members to find places more community-oriented when they become civilians.