One of my buff orfingtons has spent the last three days sitting in an empty nest box except for when I have manually picked her up and set jer in the run, She then sits right down where I set her only to get up a few minutes later and joing right in with the other chickens normal activity like nothing is wrong. She will hang out for about ten minutes then go straight back to the coop to get on the same empty nest and sit. I am new to the chicken business and she seems to act and have all the symptoms of a broody hen but there is no clutch of eggs or even a single egg she is sitting on. When I do put her out of the nest and into the run she acts normal. Could she be broody without a clutch or even one egg in the nest. She is about 11 months old and has been laying. Any advice????