[chrismahon]

It does sound like an overhead attack from a buzzard, despite the weather. Dogs and foxes grab the head and shake until they bird is dead. Mink, stoats etc will go for the throat. In my experience foxes always eat the head of chickens first, but not sure what they do with ducks?

[Steph Hen]

Stoats attack on the back of the neck on rabbits, maybe same when attacking ducks? How far down the back was the cut? I don't know where mink aim for. Sparrow hawks on pigeons and a couple buzzards with phesants I've seen (maybe not killed them but making quick work of them) have started from the breast of the prey. I would have thought a buzard would grab it with claws and then use beak, so perhaps expect several cuts?
I would go for stoat or mink.