For the past couple weeks I've been noticing feathers on the ground and in the coop... but I haven't really noticed anything on the chickens... well today I went out and my one chickens had feathers missing from underneath her belly... and on her back... both of there were 2 pretty big patches and her tail feathers are majorly thinned out and the WHOLE bottom of the coop is covered in feathers. I don't notice any of the others really doing this to themselves! And I don't know if they are doing this to her or if it is herself, but I don't see how they'd peck her belly? Please Help what do I do... what do I look for to find out whats wrong?!? I have 6 cochin chickens and 1 silkie rooster they are 6 mths - 3years old. They are kept in a coop with a run @ night and during the day they are allowed to roam our property. We also have 7 ducks and 2 geese but they are kept completely separate.