From your original post it seems that you haven't actually witnessed the feather picking, just seen bald and red backs on your birds. Is that correct?
If so, there are several possible reasons they could be losing feathers in that area:
Overmating by an active roo (see previous post re saddles etc)
Mites or parasites (can be tackled through use of topical powders or skin drops, and accommodation needs to be thoroughly de-infested too)
Feather picking (the most complicated cause to tackle)
Moulting (perfectly normal, just give the birds some extra TLC in the form of boosted nutrition to help them through it and watch for any signs of pecking on the resulting bald bits)
Poor nutrition and resulting general poor health (ensure you're feeding the correct feed for the age and type of birds and that their diet is well balanced with all the nutrients they need)
If they ARE picking each other, there are a few causes you could try to eliminate, but it's hard once they're in the grip of a strong feather picking habit:
Boredom (give them stuff to do - a 'peck-a-block' treat, veggies strung up in the runs, mirrors, strings of old CDs to play with, etc)
Low protein (try increasing dietary protein by giving sunflower seeds, canned tuna (in spring water not brine), mealworms, and scrambled or chopped boiled egg)
Low calcium (try offering oyster shells free choice, or give a commercial calcium supplement, or add some dairy to their diet such as plain live yoghurt or milk mixed with their pellets to make a wet mash, or bake and crush some eggshells and sprinkle on their feed - or all of the above!)
Overcrowding (reduce number of birds per square foot)
Sheer bad behaviour or aggression (try identifying the worst offenders and isolating them in a 'sin-bin' cage for a few days - when they come back they'll be lower in the pecking order)
You can also give some of the chemical deterrents a go - there is a thing called Ukadex here in the UK, which you spray onto the most badly affected areas of the birds and which smells and tastes truly disgusting. One beakful of that and they'll think twice about pecking again. It may also be called Stockholm Tar I think. Not sure what you have in the States but you're sure to have similar stuff - anyone chip in here with a brand name?
What I'd definitely do in the meantime, whatever the cause, is get some Gentian Violet or Blu-Kote onto the reddened bare skin. This is a blue antiseptic dye which discourages further pecking of sore areas by disguising the redness. If there is pecking going on, you DO NOT want it to escalate to the point where blood is drawn. Cannibalism becomes a real risk once that happens and can end very nastily indeed. Anyone with any wounds already must be separated ASAP.
So, try and identify the cause from those above, and in the meantime, cover those bare sore backs in Blu-Kote. If you need more help in any one specific area (ie you need to know about good products for mites), come back to us!
Good luck!
