16.5 inches long. The Lesser Scaup is a medium-sized diving duck with a light blue bill. The head is slightly peaked on the crown rather than rounded. The head of the male is mostly glossy purple but can have an occasional hint of green when seen in the right light. The body is whitish-gray with a slightly darker back. The female looks completely different with a brown head and body with white mottling on the sides. She has a white patch on the face at the base of the bill. Both male and female have yellow eyes. In flight the Lesser Scaup shows bold white secondaries with lighter white primaries.