Well, this piqued my curiosity, so I did some checking: (caution:graphic)
My vote for the killer, if not a raptor, goes to a mink or other weasel. Weasels kill by biting and severing the spinal cord behind the head, then moving around to tear out the throat. The photo with the single track has 5 toes in an arrangement like a weasel's. I believe the den belongs to the weasel-they cache their kills in their dens.
(sometimes when you find a dead bird(s) in its pen, drug to an opening and left there, likely a weasel was trying to cache it--raccoons are more than strong enough to take them out-One took my lt Brahma hen 20' out of a tree, chased her across the yard, drug her 60', over a 4' fence, and 20' into my neighbor's yard) Male minks can get fairly large, more than large enough to do the deed and leave good-sized footprints.
The photo with 2 clawed prints very close together appears to be a skunk's. The photo with a 4-toed print is a possum's. The rest of the damage appears to be caused by both of them: as a general rule, skunks and possums both pluck and eat their prey where it falls, thus the feathers' placement under/around the body. The rib cage has been chewed and torn to get to the heart/innards, but the chewer had weak jaws: a dog or raccoon or mink has strong enough jaws to demolish the ribs.
Vote against dog(fox/coyote,etc): They usually carry the victim off and the damage is more straight forward-chewed and ripped apart, feathers everywhere and still attached.
Vote against cat: my experience with cats is that they tend to go for the shoulder meat, biting off the wings, or at least plucking the 'arms'.
Vote against raccoon: raccoons don't generally chase their prey down. Also raccoon damage is textbook: they go for the head, biting through the skull/beak before chewing off and eating the head/brain and most of the neck and blood and the crop/gizzard. They then pluck the breast (sometimes thigh), and eat the entire breast/thigh muscle down to the bone, very clean-no or little chewing of body bones. They will also drag their prize to a safe distance from the kill site before digging in, resulting in feathers strewn over a large area. I am not familiar with raptor damage, so I can't vote yea or nay. The feathers seemed spread over a larger area the next day: I would guess someone came back for leftovers and, finding none, snuffled through the bits of bloody feathers.
Whew...long post, sorry
