Thanks, all, for your commiseration and help. This was a well established flock of 12 adults (4 roosters) and the new flock of teenagers (15 weeks) I had 2roosters and 5or 6 hens the day after the big tragedy. Then more disappeared. Yesterday I had 1 rooster and 4 hens. That's what I still have today.
I have a german shepherd. He was in the garage when it happened, in his crate, because it was supposed to thunderstorm, and he has "issues" with that. He isn't a guard dog, but he takes no notice of the chickens. They all walk right around him. No tracks were left, that I could find, but its mostly woods and grass, not much mud or dirt to look in. We live in very rural area. No neighbor dogs. thieves would not have been able to round up the chickens! I still hold out a tiny hope that they might be out there somewhere, but you would think I would be able to see them up in trees, or at least hear them, wouldn't you? How far away could they go? Some people I have talked to here think it was coyotes. Some say dogs, for sure. Some say absolutely racoons! Even if one of those took off with a few - Where did the rest all go? It's driving me mad. I am thinking of getting an Anatolian Shepherd Dog to guard the future birds. And a wildlife camera for night shots. And traps. And a bigger gun. And a llama, just for good measure.