Coyotes would have made more of a mess. The puncture wounds on your hen's neck and the fact there was very little blood on the others makes me think weasels. They will bite the neck or under the wing and then lap up the blood. I lost a bunch to a weasel during the night several years ago. The missing ones, however, to not make sense for it to be a weasel. At least not around here. Ours are too small to carry off a chicken. A mink, however, is big enough to carry them off and part of the same family is a weasel, so maybe it was a mink. I doubt it would have been both, but you never know. I don't know if a mink will bite them then drink the blood also, but I suppose it's possible.