My guineas were all hatched together and raised together in my chicken coop, which is enormous, chain-linked with a netting over the top to keep hawks and such out. They're 4 years old and just killed one of their siblings. I don't understand it, they've gotten along all these years and I didn't see them picking on my lavender at all, just found her dead, with her neck plucked clean and bloody. Why would they suddenly do this? I know it was the other guinea, because my chickens are all very mellow and don't get with the guineas except to eat and scratch.