We've been pondering this issue. I got it wrong before. The chickens roost in the rafters of the old garage. The guineas roost at the top of a Bois D' Arc tree next to the cattle lot. My sister doesn't have a chicken coop. The theory was that the guineas are really stupid birds and probably came down earlier at dawn and got whacked. But guineas are not easy to catch in any case and for something to tear off one of their heads...well it would make some noise. Early morning walk around the place didn't produce any evidence of something able to tear off their heads. Sardines and the traps were set and we got nothing. There also hasn't been any headless corpses lately either. So there is that.