Have you ever had chickens before, I have. Chickens can do lots of silly things. If you have a chicken who has been camping out on a nest she is probably broody. Some ways to know if you have a broody chicken is if approached she will puff up twice her size and make, a sort of growling noise. Also If you get your hand to close she might give you a hard peck. I always wonder If they get depressed when you take their eggs.