I don't know if anyone is following this anymore, but I bought three new Coshen chicks and two new Buff Brahmas. The chicks are in a cage on the back porch and the two Buffs were in the chicken house. I changed the water every day.
I went up this morning, as I have every day, and one was dead and the other was missing. At this point, I have to completely revise my assessment from earlier and say that I do, in fact, have an animal getting to my flock. Maybe.
The Buffs were adolescents, so they were the size of full-grown chickens. The one that I found was in the chicken house, no visible blood, but I did check the feathers and there is some evidence of possible bites on the rear end. Broken feathers and some skin breakage, but I've only had them a few days so I don't know them well.
What's odd is that, where I saw broken skin, I saw maggots. Or what looked like very tiny, skinny ones. The head on the chick was still floppy and the wings easily movable, as if he had just died. If that's the case, how could there be worms so quickly? I cannot find the female of the pair.
I'm about to give up on chickens. For this to be my first experience is pretty awful. I can't believe this is so hard.