Northern Duck is a term used to describe three species of waterfowl that are found in the northern hemisphere. These species include the EIDER (5 letters), SMEW (4 letters) and YEW (3 letters). The EIDER is a large sea duck that is found in coastal areas of the Northern Hemisphere, while the SMEW is a small diving duck that is found in Eurasia and North America. The YEW is a medium-sized diving duck that is found in the northern parts of Europe, Asia and North America. All three species of Northern Duck are characterized by their distinctive plumage and are popular among birdwatchers.