Male Ring-necked Ducks are bold black-and-gray ducks with a dark head, black back and gray sides.
Females are rich brown with a contrastingly pale cheek and a whitish eyering.
Both male and female have a grey bill with a white band and a black tip.
Despite the name, the ring on the neck is almost never visible.

1st & 2nd photo: Bosque Del Apache National Wildlife Reserve, San Antonio, New Mexico, USA, 14 January 2019
3rd, 4th & 5th photo: In the company of a Ruddy Duck. Lake Roberts, Gila National Forest, New Mexico, USA, 12 January 2019