Covers and having cleaner with you are about the best option but around our place grackles are thicker than fly's and crap on everything so to get even with the sons of b's I keep the local walmart in business buying BB's !!! Yep I shoot the CRAP out of them throw em out back in the field and get the added benefit of keeping the neighborhood Kitty's busy and off my car... This may not be politically correct with "grackle lovers" but I HATE GRACKLES...