Most of my kayaks are left outside in the winter, on racks, that I have bolted to the sides of my shop. They are on the east and west sides of the shop. They are are stored upside-down, with hatch covers ON and cockpit covers OFF. If the cockpit cover is left on, it fills with water. I cover them with white polyethylene tarps, wrapped with bungee straps, and held to the rack with bungee straps. I am in central New Hampshire and unwrap them every spring expecting to find mouse/squirrel/chipmunk damage, but after 5 winters of this have not found any. If I leave one of the white poly tarps folded up on the ground it will have rodent damage in several places, but never on the boats.