The white banding on the Male Ring-necked Duck in Winter is very distinctive and unlikely to be confused with other species, however it is known to hybridise with the Tufted Duck in which case the rings will be much less prominent and it will likely have a small crest.
The Male Ring-necked Duck in Winter is a black bird with light grey flanks and a bright yellow eye. Its bill is grey with a wide black tip and a white sub-terminal band, it also has a white band around the base of the bill making it distinctive if seen clearly.
Adult Male Winter
General distribution: The Ring-necked Duck is an American species and is a rare but regular vagrant to Europe. It is also a common escapee from wildfowl collections.
Habitat: Breeds on freshwater marshes and ponds often choosing acidic water. As a vagrant it can turn up on almost any area of freshwater, it is not adverse to very small pools and ponds unlike most diving ducks.
Notes: The Ring-necked Duck is well known for breeding with other Aythya species and hybrids often present an identification challenge. Pochard, Scaup and Tufted Duck are not uncommon vagrant hybrids.
The Female Ring-necked Duck has rufous brown flanks, a dark back and a peaked dark crown. It has a light eye ring and a greyish face with a pale line running from the eye to the ear coverts (tear line).