naked necks on not NN chickens

[aussieheelr]

My 3 yr old white rocks (none of the other birds) are getting naked necks. they all roost on the roost built to be a roost, 2x4 with 4" side up, right next to each other. Production has really died off, from 12 a day to 6 from 16 birds, and I'm seeing some feathers around the coop. Could this be moulting?
History: I got chickens last June and these older birds joined in September. No problems until about a month ago their necks began to go bald.
I'm hoping it is a bad molt since I haven't ever really seen one from my birds yet.

 

[peaceful]

possibly it's moulting. I had naked necks on some of my birds one year and I never did really figure out the cause but it went away. Although one of the girls became sick later. Anyway though, overall it cleared itself, whether it was moulting or no. If it was mites or something of that nature, the only thing I did was put wood ash in their run for them to dust bathe in (ashes from a wood fire, like from a woodstove).
Are your birds picking at each others necks for some reason?
Here is a picture of one of my girls naked neck:

 

[aussieheelr]

I hatched some new chicks about 3 months ago that have now joined the pack so maybe they're re-working the pecking order, but I haven't seen any fighting or bickering. I don't have a wood stove but we could certinly have a bonfire one night and use those ashes, good excuse to have a marshmellow roast.
I'll try that with the ashes.