100+ pages so I haven't read all the comments. But I gotta vote DOG! Neighborhood dogs.
Hen & Rooster loss tally
Dog - 5
including a wiener dog that got in through my yard fence, then the chicken house fence, then killed three hens in a matter of seconds *while* I was yelling at this dog and actively chasing it out of the yard. A cuddly, bouncy, goofy, lovable, maybe 3 lb wiener dog. (Always the ones you least expect!)
Hawk - 1
Mink - 1
Unknown - 3
likely fox or opossum. Something that takes the bodies, and is bold enough to take on a huge aggressive duck. We have coyotes come into town as well, but I don't think they'd get through the yard fence without a lot of clamor.