Pictures of chicken butts - is this hen pecking? or something else? what do I do? backs are bare

[ve]

Bare backs can be from the rooster, but bare buts, chest and bare around the big tale feathers suggest feather picking. It may be caused from crowded conditions (which is not your case), or something missing in the diet. 18% should be good, but if they are doing it, something is missing.
I had this issue and people on here advised Sunflower seeds and meat and it worked very well. Few times I gave them raw ground beef.
Pictures are not perfect. Please show more from the top, so we can see tail area, the back and some neck pictures.
Also continue checking for lice and mites as -tolkinboutchicken- suggested.

 

[Mrs. K]

I can understand your wish for natural remedies until it comes to parasites. If you do have them, you need to use real pesticides or your birds will suffer. But follow the directions.