Species, Age and Sex Identification of Ducks Using Wing Plumage

Black Scoter

The underwing of all ages and sexes is completely dark and unpatterned. Adult male wings are easily identified by the extremely attenuated outermost primary and the completely black upperwing. Adult female wings are dark brown. Their tertials normally have bluntly rounded unfrayed tips. Greater coverts are broadly rounded and unfrayed,often with poorly defined white areas near their tips. Wings of immatures of both sexes are a deep brown. Tertials are relatively short with frayed tips. Greater coverts are frayed and faded at their tips. Immature wings are about the same color as those of adult females. Although male wings are slightly larger than those of females, there is much overlap.

Wing Character	Male		Female
	Adult	Immature	Immature	Adult
Outermost primary	Deeply attenuated for 55-60 mm. from the tip; shorter than adjacent primary	Not attenuated but noticeably narrower and shorter than the next primary
Tertials	Shiny black and acutely pointed; approximately 30 mm. longer than most secondaries	Dark brown and sharply pointed; often faded at their tips		Very dark brown and bluntly pointed; approximately 20 mm. longer than most secondaries
Tertial coverts	Shiny black with rounded tips	Dark brown; narrow slightly toward their tips which are usually slightly frayed and faded		Dark brown; with rounded tips
Greater, middle, and lesser coverts	Shiny black with rounded tips	Dark brown; greater coverts often slightly faded near tips; appear rough		Dark brown; may be faded at their tips

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