My hen (3 years old) is sitting on the nest in the hot roosting box, nonstop. We are in AZ so it's worrying me. We don't have a rooster and do not want one. She will not be hatching anything so I remove all of the eggs periodically throughout the day and coax her out of there. She returns shortly after I leave the area. She actually sat in the box all night last night, alone, normally they all roost together on a bar. This has been going on for 4 days now. Is it possible this is an illness rather than broodiness? She is a black australorp.