From what others have told me, it could be anything from hormones, over-friendliness with the caretaker (which pulls you into their pecking order), the victim being sick, lack of space, lack of rooster (like you said), amongst a million other reasons. Chickens really are their own animal.It is very sad because we've raised her since she was a baby and showered her with love. I don't know why she's aggressive.
