They learned pretty fast. I thought about a 12 ga. but I'm concerned about the damage to the paint. Now I just keep the garden hose handy and wash the bird crap off every day."I even tried taping a picture of a cat inside my truck right where they sit."
Stuff like that only works briefly. Once the animal sees that the picture or decoy or whatever isn't moving,, they ignore it. The same thing goes for plastic owls, rubber snakes etc.
Unless you move the "predator" around 2-3 times a day,, they quickly learn it's fake.