well i havent needed to do it because mine are indoor ducks. but when they were smaller and were kind of outdoor ducks and i had 2 chickens a fox came and killed my chicken. because in the uk they are vermin and were legally allowed to kill them, so much soo that if we catch one on purpose or accedently we have to call the animal services to come put it down. when one killed my chicken i left my ducks and remaining chicken outdoor one night alerted the neighbour that they might here loud sounds and sat in the window with a cross bow. got rid of 16 foxes in 2 days but my duckies chase them off anyways. but like i said it isnt a rule because a hungry fox or a fox with babies will hunt in the day. especially the hungry braver ones. just most of them are nocturnal naturally but they are smart horrible critters.