@KlopKlop
If the guts were eaten, I would look for an opossum. I have had one out here wandering around the last couple of weeks. You can pick out the tracks with the tell tale scalping in the snow by its tail. I think I have had a fox out around the property too, just like your tracks, too long for a cat, feet not quite big enough for a dog or yote. The fences are up and all but 4 birds are in closed pens.
@lalaland
The feather mites chew off the barbs from the quill. This is the worst I have seen them. His feathers looked greasy. Normally you will see a bad infestation on a sick bird. He is perfectly fine now that I treated him, acting downright spunky yesterday even. I treated all the girls when I split him out too to make sure I didn't have the whole flock of NH getting them. I need to get some Sevin in the bedding too to make double sure there isn't some of them crawling around in the pen. It is tough avoiding all creepy crawlies in my case because I unfortunately do have wild sparrows getting into the coop and the pen. The coop, I am assuming, they are coming into the end of the ridge vent. The runs have 4" openings where the roof meets the south side framing.
It looks like the end of this week is going to be hovering just above freezing, and a week later we will have single digit highs. We will get normal winter weather after all. I just hate the wind when it gets that low. I think my birds will tough it through. I did lose a Cornish rooster yesterday, but it wasn't the cold. When I set up the bachelor pen, he got beat up and then got sick after than when his defenses were down. I had been treating him, but I wasn't sure he would make it right from the start. It was one of the WLR roosters. I have debated keeping the WLRs but every time I think much on it, I come out keeping them. I am hopelessly entrenched in my addiction.