They don't seem to actually be cannibalising or eating the feathers. Just pulling out tail feathers on a couple other hens (only two so far)... I've watched them do it: they'll just yank one out as the other chicken walks by and drop it on the floor. They don't play with the feathers or eat them or anything. And they don't go after the chicken more than that. Very strange! They are getting protein feed and corn scratch, plus lots of insects and forage, so I don't know what could be going on. They have plenty of room... They are at the age where their long tail feathers are just coming in (a couple don't even have them yet) and I have seven kinds of chickens in together, so I'm not sure if they just think the feathers are odd??? It seems to be mostly the black australorp and welsummers that are doing the plucking, though there may be others... Need to set up camp out side the run and watch more. Any suggestions? I heard white vinegar in the water can help, and perhaps sunflower seeds? Thanks all!