My black australorp, Helen, very curiously has a bald butt. It's been like this for a week. My thinking is that the hens are getting bored and testy with each other, as we've had them penned up more often than normal for the past couple of weeks - it's been too cold and rainy. But this is such an odd place to pluck at, whether she's doing it herself or not. I'm not sure what to think. I've never seen the others harass her so I'm not sure. Do bully chickens peck at bottoms like this? Anything I can do to help her? Other than this the flock has been looking healthy as ever. What do you think?