I have this one RIR who is pretty close to the bottom of the pecking order. A few days ago I noticed that she had a lot of pin feathers, or feather spines I guess you'd say, around her face and in patches on her neck. I tried to catch her to get a closer look... but I accidentally grabbed the tail and pulled a bunch of tail feathers out. The feathers I pulled out of her came out VERY easily. None of the other chickens have this happening to them. Could she be deficient in some mineral? I haven't been offering them as many oyster shells as I should.. Could the lack of calcium be the problem? Its also been very cold and snowy around here.. could that be it? I will post pictures later. Thank you!