I have 16 pullets, 23 weeks old,starting to lay. They have more than sufficient room and nests,constant food and water supply,access to outdoors for 12 hrs. daily, 14 hrs. of light [40 watt bulb in a 6 x 12 coop] daily,[lighting was brought up gradually starting at 18 weeks to 14hrs. at 22 weeks. In the last week or 10 days I noticed that 3 of my RIR's are getting bald spots on their backs at the junction of the tail and back feathers. Several of my barred rocks are picking at these three. I have lowered the wattage of the lighting[to 20 watts] turned off the heat [a red heat bulb].They have a constant supply of feed[recently switched from grower to layer] and water. I keep it very clean in the coop. They also get 2 lbs. of scratch grains daily[1/2 in morning in the yard,1/2 in late afternoon in the coop] Is there anything I can apply to the bare patches on my birds before someone draws blood? Is there anything else I can do to deter this bad behavior short of removing the offenders?