Give them some kind of extra protein every other day. This is what I had to do to finally get rid of the pecking. I give them scrambled quail eggs, or ground sheep meat, or moose liver chopped up every other day. (Just happen to have these things in abundance, you can use other sources as well.) I also add Cod Liver Oil to it, because of the winter, we don't have as much sun as we do in the summer, so they need some source of Vitamin D. Lack of sunshine, or Vitamin D will make not only chickens grouchy, but humans as well.
