Feather loss and off behavior. Do I have a disease or behaviour issue? w/ pictures

[bobk]

I have 9 hens, 6 rir and 3 ee about 15 months old. within the last 2 weeks I noticed the one of the easter eggers with some bare spots and not staying with the pack, if they went out she went in, etc. not eating. I setup a separate coop for her and she has been in it a week, putting on weight slightly but still not going nuts for treats.
Today I noticed a mess of feathers n the coop floor and sure enough a rir has some bare spots and also some of the neck and head feathers on these birds has white tips, see pictures. Sure enough when I went to pickup and move the rir to the separate coop and she flapped her wings feathers flew everywhere. Also egg laying is down to nothing 2-3 eggs a day average but it is only light out here from 620am-400pm

If I didn't know better I would say moulting but they wouldn't moult in winter would they? so do I have a disease problem or a behavior problem? I have a lot of photo's to show the 2 I have isolated and then some of the others

 

[chicmom]

They usually do molt in their second autumn, and I believe yours are at the right age for molting. So they're a bit late but it can happen at this time of year. And maybe the weather is a factor too because here in Ohio, it's been unseasonably warm. I would look at them very closely though, right down the bare skin under their feathers to make sure they don't have mites or lice. Wild birds can pass along parasites to your flock. If you do see some critters, powder them up with some poultry dust or Seven dust and clean out the coop real good. Powder them again in two weeks. Others may have a better solution, but that's how I do it.

Take care and have a happy new year!

Sharon