Hen plucking and eating feathers off of others

[Mackaarina]

Hello everyone.
I have a problem with 1 hen, she keeps plucking off/eating feathers of other hens. It came to the point that one of my hens has bare spots on her thighs. I've noticed today that 6 of my other hens don't have saddle feathers, just fluffy inner ones. And I saw her plucking off feathers of them. None of the other hens do this, only this 1. It is not an aggressive plucking, she just comes to them, see feathers plucks them off and eats... The run is 8meters in length and 3.50meters in width and I have 9 chickens, they are 10 months old. I feed them layer pellets, (min.17% protein, vitamins and other minerals included), wheat and few days ago I added sunflower seeds and pumpkin seeds, I bought the ones in small bags from the supermarket because our farm stores don't have any other feed for hens except layer pellets, wheat, crushed/whole corn. Occasionally I feed them fresh grass, zucchini. The coop is kind of small I know, it is 130cm in length and 110cm in width, the height is 110cm, it has good ventilation. I cannot upgrade it at the moment cause I'm overloaded with work, but still... they haven't been having problems all this time til now, I don't know why she does that. I was carefully watching them today and none of the chickens plucks feathers except this 1, and she seems to be enjoying it. I wanted to separate her in the same run but I don't have any equipment for that, and shops are closed due to the covid-19. I could put her in the attic for a couple days, but then she would be away from her flock, not sure if that's a good idea? Any advice/suggestions would be appreciated!

We just had the same thing happen yesterday. We have nine girls and caught one of them walking around while the others were eating and she just plucked their tail feathers out! some only have one left. Caught her on our run cam. We put her in a cage in the coop late afternoon yesterday and wracked our brains trying to figure out why. Moved her in the cage into the run with the other girls today and she stopped pacing. She Really needed to be with the other girls. Gave her some worms and feed and put Rooster Booster in her water and in the water of the other girls. I think we realized the problem. Before I was giving them a flake or two of straw in the run about every two or three days since we put them out there. They would stay busy all day scratching it and pecking at the seeds in the straw. About 2 weeks ago, stopped putting in the straw in the run because the straw was so thick in the run. I noticed they hadn't been as active lately and that could be why. We think she is bored. We will release her from prison on wednesday night and put fresh straw in both the coop and run. Also cleaned their mirrors off, hung a kale ball in the run and put an apple (cored) hanging frum a chain. Keep your fingers crossed! We also have been spraying colodial silver on the areas that were bleeding on the other girls tail feathers. I hope this works.