Common Merganser Identification Tips
(Credit: U. S. Geological Survey)
 
General Information
- 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.
 
 
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