Ring-necked Duck, Aythya collaris

Ring-necked Duck, male, 1/15/08, Santee Lakes, San Diego Co
The obvious ring on this duck is the one around the bill, but the picture above shows that there really is a ring around the neck, however cryptic.

Ring-necked Duck, female, 1/14/08, Santee Lakes, San Diego Co

Ring-necked Ducks, pair, 2/10/09, Gate of Heaven Cemetery, Los Altos

Ring-necked Duck, male, 4/29/10, Agua Caliente Park, Tucson, AZ