I am very new to backyard chickens, so I am hoping someone can help me understand my chicken's behavior. (We love our girls very much, and most of all I want to make sure she isn't ill; she appears normal in all other ways.) We have 4 hens of different breeds, all under 1 yr of age, no roosters (we are not in a rural area), and they have been laying eggs for about 6 mos. Our Buff Orpington has been sitting on eggs (her own and those of other hens). Is this because we are leaving them in the nesting boxes too long? Or is this a normal behaviour (fertile eggs or not)? Please advise, and thanks in advance.