I have 5 hens: one is a bantam (came from the wild neighborhood chickens), an americauna, three that are supposedly maran's,(not sure if spelled right two are black and one looks more like a rhode island red. I also have a 6th one that was also from the neighborhood chickens, she is almost 4 months old. 
Of the 5 my bantam lost her tail feathers, some wing feathers and other random feathers throughout her whole body. She now has little white feathers poking through her other feathers and has not laid an egg since March or April. She went broody on me (not the first time). The other times she went back to laying (she is also the only one who lays tan eggs). This time she hasn't gone back to laying. The 5 are a year old this week.
One of the black ones also lost her tail feathers and my americauna is now randomly losing her feathers and not in any one particular place. I picked her up the other day and about 10 feathers fell off of her. The other day I looked in the hen house and there were white feathers everywhere. The run itself looks like her and a black one got into a fight there are black and white feathers everywhere.
I am in Sacramento and our weather goes from the 80's to 100's.
They are all eating somewhat during the day and a lot at night before they go to bed. I check to see if their crops are full. I know with the heat they tend to eat less just like we do. They have been going through water like crazy and I have two water containers for them each a gallon. so they are drinking at least a gallon a day.
I have been giving them feather fixer (which they love) along with their layena food. Yesterday I actually bought layena pellets since the feather fixer is in pellet form and I mixed some feather fixer in with the other food so they weren't just eating the fixer.
I have checked them all for any type of bug and don't see anything. They are acting perfectly normal, just losing feathers, one not laying at all and the others I get from 1-3 eggs a day but since the rest lay different shades of green eggs I'm not always sure who is laying them and who isn't.
Any suggestions or thoughts are greatly appreciated.