Mocking birds will peck them to. Keeping Jays out of pecan trees is hard. They are real smart. They will fly out the back side of the tree and fly a hundred yards or so and then turn to what ever dirrection they need to go. They keep cover when they know you are after them.
A lady near here hangs a crow under her pecan trees, hanging upsidedown by one leg so it is highly visible all spread out. She said it has worked for crows for years. Don't know if it would work for J's. eddiegjr