RE: Decoys for yotes?
I don't think your experiment will work well and here's why. Coyotes are all individuals, much like snakes for instance, and in that means that each will respond differently to the same situation. You'd have to find several coyotes that were the same in dominance, the same in hunger, the same in attitude, etc. Let's say you were using a black bunny and you had a coyote that hadn't eatin in two days and was the dominant male in his core area, and he comes to your calls and sees your "decoy", do you think he will respond the same as a coyote that sees the same black bunny but is female that is not in her core area and has had a good meal with-in the last 24 hours?
Some coyotes shy away from even the littliest decoys? Why would that be? Yet some coyotes charge any decoy they see!
SO, IMO, you're wasting your time! Also, coyotes don't see color as we humans do! Another little clitch!