Besides hawks, raccoon, and opossum eating a bird thru a fence, we should also consider the skunk as a predator that does the same thing. A skunk does eat the flesh, drinks the blood and often crushes the head to consume the brain....per my experience with skunks. Does the weasel do the same?A young raccoon or an opossum is my guess. They managed to grab the wing and blindly pulled without thinking too much about it. Probably got interrupted before it could finish.
She said it wasn't very stiff so it would've been within a couple hours of finding it.