Hi everyone, We are new to chickens this year and this is our first winter. We have 3 laying hens and it's been below freezing here for the last couple of weeks. Our Barred Rock hen is completely bare on her bottom but looks normal everywhere else, The other girls seem fine. I haven't noticed any aggressive behavior out there and she is still laying but I am concerned. What do you think this is? What should I do? Thank you so much for your help!