I'm not understanding why she's segregated form the others. Unless a chicken is very sick and vulnerable to abuse from the flock or injured so as to invite wound pecking, they do much better if left with their mates.
Chickens absorb vitamin D through exposure to direct sunlight on their...
Darned if she doesn't look like a penguin standing there. That extreme vertical position has me stumped. Female chickens have a normal stance where the center of gravity is thrust forward. This stance is even more radical than the rooster stance.
I'm at a loss as to what could be causing it.