I used to try all kinds of crap like that. Used to make plain old white kites with varying degrees of success. (Mind you, success was determined by being able to keep it airborne while unattended, NOT if it helped kill birds :lol: ).
The best idea I ever had (and it actually decoyed birds) was the simplest. We'd take alternating white and black ballons tied to a line on two poles. Much like those "string-o-wings" things. Worked pretty good for a few years in the early/mid nineties.