Coyote/Fox Question

Probably a bobcat or even an owl or hawk

Fox and coyote will drag a kill away, but I rarely find evidence out in the open as foxes carry the kill to their dens and coyotes just go off in private.
Was there a branch, power line or other structure over where you found the remains? A large raptor could have done this and eaten the easy parts before dropping the rest.
If not, a cat can do this.

Neither. Fox, coyote, bob cat are going to eat the whole bird.

Head gone and gutted is the give away for what it is. If it was one of the above you'd find nothing. You're dealing with a raccoon, mink, or possum. They will pull the head off and eat the crop.

Look for prints near what you are finding. I would bet this is a bobcat recently working your area.

Only one way to figure it out. Set some dog-proof traps, some giant live traps, and some humane dog noose traps. Bait them with eggs, canned cat food, fresh chicken meat, and fox bait (like beaver meat) and see what you catch. Use chicken shite as a cover scent but wear nitrile gloves while you’re setting up the traps.

I vote for coon. That's exactly how they have killed several of our chickens.

Have a heart traps with cat food or dog proof traps work very well on them.