Common Merganser Mergus merganser

Identification Tips:

• Length: 18 inches Wingspan: 37 inches
• Large, sleek diving duck
• Long, pointed bill with serrated edges
• Red bill is thick at base, tapering towards tip
• Sleek, tapered crest, more obvious on females than on males
• Brown eye
• White secondaries
• Immature similar to adult female, often with a less-distinct chin patch

Adult male:

• Greenish-black head and upper neck
• White breast, flanks and belly
• Black back and upperwing coverts with white scapulars
• White secondary coverts crossed with indistinct dark bar
• Alternate plumage worn from fall through early summer
• Male in basic eclipse plumage similar to adult female

Adult female:

• Red-brown head meets pale breast in crisp line of division
• Well-defined white chin
• White breast and belly
• Pale gray body plumage

Similar species:

Adult male in alternate plumage is somewhat similar to male Red-breasted Merganser but has white breast and flanks, and a less obvious crest. Female, immature and eclipse male distinguished from similarly-plumaged Red-breasted Mergansers by sharply-defined chin, reddish head contrasting with white breast, paler gray plumage, sleeker crest and larger bill. In winter, Common Mergansers, unlike Red-breasted Mergansers, are generally found in freshwater habitats.

Length and wingspan from: Robbins, C.S., Bruun, B., Zim, H.S., (1966). Birds of North America. New York: Western Publishing Company, Inc.

Above information used courtesy of United States Geological Survey.