Need help,chicken plucking feathers out of my ducks and chickens

[bstala]

My chickens and ducks look horrible except for 1!! I need help to make her stop! She has been doing this for months and now it's getting to be a problem. I've heard about putting vinegar on their feathers,does that work? Thanks!

 

[PimpinMunky]

My 3 female chicks are plucking and eating the male roosters chest feathers. He is bleeding and raw in several spots. I am not sure the cause of what to do except another thread suggested protein deficiency. The remedy was tuna fish.