Hello all. I have 6 four month old girls and have had them since they were two days old. They have always been friendly and like to be petted and held (for the most part). I usually sit in the run with them on a little stool and rub their chests as they come up to me and sometimes pick them up if they seem interested. Today when I went to rub her chest, one of my girls actually bit my hand really hard, grabbing skin in her beak. I nudged her away and she came back at me again and bit me. I ended up picking her up on my lap, which I have always done. And she went into this weird posture that I've never seen any of them do before - she kinda spread out her wings a bit and pushed her rump way up in the air, kinda like a cat in heat. She has always been the brave one, and if she didn't have the classic feather pattern of a female black sex linked bird, I would swear she was a rooster in the making. Her comb is so much bigger than her sibling. I've attached a picture of them side by side. It's a little fuzzy but you can tell the difference between the two. So what can I do about this aggressive behavior before it gets out of hand? The rest of them are as sweet as can be.