Adult Duck Killed

[Nuka]

Hi all,
I've had my ducks for 4 years and nothing has ever bothered them. This morning I discovered a pile of feathers and the head of my male inside the fence. I've checked around the fence and the surrounding area, and I found 2 small feathers towards the direction of some overgrowth and woods. My hens appear fine but spooked. Any idea what type of predator could do this? I live in the Upstate South Carolina area for reference.

 

[nuthatched]

Sorry to hear about your birds.
Can we get pictures of the pen? Is there large openings? Fist sized or like that?

 

[Nuka]

It's a wooden fence with chicken wire around the bottom half. I'm at work at the moment so I'm not able to take any pictures. My large dog borders one side of my duck pen, he was raised with them and in the past, has barked when any owls, buzzards or hawks have been nearby. My stepfather has recently put free-roaming chickens in the backyard, and while occasionally one of them would disappear, the ducks never had an issue.

I'm really confused because I've never heard of a predator that decapitates but doesn't take the head.