Headless

Found this headless corpse in a Philadelphia churchyard; it was too beautiful to ignore.
I wish I knew what bird it was. Can anyone tell me?

Edit: Talpa suggests Green-winged Teal and it does look like one.
A small dabbling duck, it overwinters in the United States and flies north in spring to its breeding grounds in Canada and further north. This one could perhaps have been brought down by a predator or an accidental collision.