The Smew is one of 3 species of Sawbills that occurs in Europe the others being Goosander (Mergus merganser) and Red-breasted Merganser (Mergus serrator). Sawbills are diving ducks with a small hook at the tip of the bill which also has a serrated edge enabling better grip of fish, its main prey. This male in its breeding plumage is unmistakable while the female, juvenile and eclipse plumage males all look very similar with their "red head". During the breeding season they live in freshwater lakes and rivers in the coniferous forests to the very north of Europe and Asia. Like the Goldeneye (Bucephala clangula), with which it sometimes interbreeds, it nests in tree hollows.