I have a Bantam hen that has been sitting on her nest for about 20 days. When she first started sitting on them there were about 13 eggs and after a week or so there were only about 9 eggs. I am guessing one of our other chickens got a hold of them??? She has been sitting ever since and I have only seen her out of her box once since then. My question is, do they know if the eggs they're sitting on are any good? We have 2 Bantam roosters so I am 99.9% sure they are fertilized. Can they tell if there is something wrong with them??