When you notice one or two of your chickens are missing look around. If there is a pile of feathers your bird was probably eaten by a racoon or a hawk right in that spot. Now if there is just a trail of feathers that stops suddenly it was probably either a hawk, coyote, or a fox. If you dont find a pile, or trail, of feathers it was probably wandering and got taken away or just ran away. Since you probably want the best for your chickens, I would sugest either getting a game camera or watching out a window before you go to bed. If more and more chickens keep disappearing set up a trap or two around your coup and bait the animal in. If it doesnt come the first night, but the bait is gone, rebait it and put a trail cam over it so if the animal does it again at least you know what is taking your chickens. After the first 5 to 10 nights and you didnt catch anything, but got pictures and you know what animal is taking your chickens, figure out what would be the best way to trap or get rid of it. If that doesnt work call the game commision or a trapper and hook up a night that someone will come and trap the animal.