The male in this photo has whiter sides than those in my previous post. It looks like he has his breeding plumage. These ducks do have a barely visible narrow ring around their neck. But the more prominent ring on their bill would seem to be a better source for their name. The name “Ringed-necked” was given to them by early biologists that named species after examining dead specimens. The neck ring is not a good field mark for a live bird!
Birds in My Viewfinder 