- merganser, fish duck, sawbill, sheldrake - large crested fish-eating diving duck having a slender hooked bill with serrated edges
--1 is a kind of sea duck
--1 is a member of Mergus, genus Mergus
--1 has particulars:goosander, Mergus merganser; American merganser, Mergus merganser americanus; red-breasted merganser, Mergus serrator; smew, Mergus albellus; hooded merganser, hooded sheldrake, Lophodytes cucullatus - sheldrake - Old World gooselike duck slightly larger than a mallard with variegated mostly black-and-white plumage and a red bill
--2 is a kind of duck
--2 is a member of Tadorna, genus Tadorna
--2 has particulars: shelduck