Male: Iridescent purple on head; gray to black bill with a white band near the tip; cinnamon collar on the neck (rarely visible in the field); black back, upper side of wings, and breast; gray sides and underparts of wings; white patch between breast and sides. Female: Mottled brown overall; gray to black bill with white band near the tip; white eye stripe. 43 cm (17 in) in length. Head is peaked.
The breeding season begins in late May. Breeding habitat includes mostly freshwater lakes, ponds, marshes, and swamps. Nesting is normally associated with water. The nest is built of grass and other plant material. It is either on the ground or floating in vegetation. It is lined with down. The female lays 6-14 (usually 8-10) eggs that she incubates for 26-27 days. The male may stay around the area while the female incubates, but otherwise is not involved further in the nesting. The young are precocial and are cared for by the female for 49-56 days after hatching.
During the non-breeding season, this duck's habitat includes the same water types as during the breeding season. The diet of the Ring-necked Duck is variable, depending on its location, but includes invertebrates and some plant material. This species takes food by diving from the surface of the water. The Ring-necked Duck is migratory.
The Ring-necked Duck occurs through most of the northern United States, Canada, and in isolated areas in central United States during the breeding season. During the winter, it can be found in the southern and coastal areas of the United States south to the West Indes and Central America.
Some birds have died from lead poisoning after eating lead shot from hunting. This species is not listed as Threatened or Endangered in any portion of the southeastern United States.
The most similar species is the Tufted Duck, which rarely occurs in the continental United States. The Tufted Duck has a crest or tuft of feathers on its head, and a much less noticeable white ring on the bill. The Greater Scaup and Lesser Scaup are also similar in appearance. However, they do not have the white ring on the bill and they have more gray on their back than the Ring-necked Duck has.