The Saw-billed Duck is a species of duck found in South America. It is also known as the SMEW, which is a four-letter word that can be used to solve a crossword puzzle. The Saw-billed Duck is a medium-sized duck with a distinctive saw-like bill. It has a black head and neck, white breast, and gray back. It is a shy bird that prefers to stay near the water's edge, where it feeds on aquatic plants and insects.