Plymouth Rocks Losing Feathers at Tail Base

[vetters2015]

I have a flock of 15 chickens. I am 99.9% sure that all of them are hens (they came sexed and I find 15 eggs every 12 hours). They were born in June 2012 so they are not that old. Just got up to everybody laying eggs daily. My brood breakdown is 6 Plymouths, 5 Rhode Islands and 4 Golden Comets. Recently I noticed that a few of the Plymouths were missing some feathers just at the tail base (where the tail meets the back of the bird). At first I ignored the issue, because it wasn't extensive. Now the issue has gotten worse, more feathers are missing and more birds are involved. BUT ONLY THE PLYMOUTHS ARE DOING IT! Almost all of my 6 Plymouths are missing feathers at their tail bases. NONE OF THE OTHER CHICKENS ARE MISSING ANY FEATHERS! I don't get it. If they were protein deficient, wouldn't all the chickens be feather eating regardless of breed? And if I had a rooster, (which I believe is highly unlikely) wouldn't he be pulling feathers on all the chickens regardless of breed? If the chickens were stressed wouldn't they all being eating feathers?The only thing I can figure is that the Plymouths are more sensitive to a lack of protein??? The skin where the feathers are missing looks pretty normal and pinkish. There isn't any bleeding/wounds/scale that would indicate any infectious or parasitic process. I believe there is feather pulling going on, but from what? and why are only my black and white girls doing it? HELP!

 

[citychickx6]

Not sure if I can be of much help.
I had a similar issue in my mixed flock. No rooster, feathers missing and broken or snipped looking just in front of the tail.
I tried everything I could think of and everything that was suggested. It was not lice nor mites but a mean hen.
What worked in the end for me was to separate the meanies from the others. In my case the culprit was and still is my California white hen. She is now in a small coop and run with the other 2 that I thought had been mean. I isolated the worst picked hens until feathers returned before putting them in with the flock that is not mean. I am slowly removing Peppers coop mates and adding them into the larger flock. Pepper is in the end going on to become a relocated hen or into the pot. The 2 hens in the coop with her will not sleep on the roost but rather cower in the nest box. I suspect she is picking after roosting since I do not see any bad behavior during the day.
I also have changed the feed to a 20% layer from Ranch-a-Way. This seems to have helped with the regrowing of feathers.
I think in my case it was started because of being bored.
Try hanging corn on the cob or cabbage in the run for them to peck at. It may help. I do this and mine seem better off for it. Raw broccoli, a flock block and many other things can be hung to give them something to do.
I also have added more roosts to the coops so no one has to sit next to a meanie if they do not want to. I have boards set up in my runs for hens to hide behind if they feel the need.
I put peet in a dust bathing area for them every 4 or 5 days I add more to help keep them entertained.
Winter is harder to deal with since days are short and being loose in the yard gets limited with the snow.

I hope something here helps. It can be so distressing to have the hens looking rough and torn up.
Best Wishes,
Babs