My first thought was mink as well. I don’t know though, because mink kills are supposed to be awful in terms of damage and number killed. I would have expected at least some blood if a mink was trying to subdue her, or more killed at once, or something. I also don't see a ton of teeth marks around the wound. It could be possible, though.
I suppose it could have been a dog but not super likely as it was inside a fenced yard and dogs would likely have killed more than one and left more damage.
She didn't actually have a ton of feathers on her stomach, so a hawk wouldn't have had to pluck a ton of feathers. I also found it suspicious that a hawk was seen there not very long afterward, investigating that area.