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Ornithological Presentation
Greater Scaup and Lesser Scaup

Study skins from the collection of the Academy of Natural Sciences

by Adrian Binns 1/05

Click here for a webpage prepared by VIREO for DVOC on this topic.

 

GREATER SCAUP

Aythya marila

LESSER SCAUP

Aythya affinis

Name

Aythya: Greek for “a kind of waterbird or diving bird”. Marila: from the Greek marile for “charcoal”.

Scaup is Scottish for a ledge that may be partially exposed at times above the surface of the water. Scaup also comes from Scaup bank which provides a bed for shellfish, which of course the birds feed on.

Affinis: Latin for “related”, as in related to Great Scaup.

Head Shape

Best seen on sleeping birds. More rounded nape contour. Peak of the head is further forward. Smaller head with taller crown peaked towards the rear of the crown.

Head Color

Usually greenish. The color of the head gloss in males varies depending upon light conditions and both species can show bright green or purple gloss. Usually purplish.

Bill Shape

Deeper at the base and proportionately larger and broader than Lesser’s. Viewed from the side, the upper outline of the bill makes a slightly straighter line.
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Viewed from the side, the upper outline of the bill makes a slightly more concave line, especially towards the base.
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Nail on Bill

Noticeably and proportionately larger. The black usually spreads out beyond the nail onto the rest of the bill tip. Harder to see on females due to the darker bill and more variable.
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Smaller black nail that is sharply outlined against the pale blue.
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White-wing Stripe

The white wing stripe typically extends out from the secondaries onto the inner 6 primaries, reaching more than half way from the bend in the wing to the wingtip.

The white wing stripe typically extends only across the secondaries, cutting off sharply at the primaries, which are gray. Some Lesser males can show ‘extra’ white, while some Greater females can show ‘less extensive’ white.
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White at Base of Bill

On average female Greaters have more white around the base of the bill, but the difference is slight and probably of not much use. -

Flank Pattern

On males, usually a very clean white On males, usually Lessers have extensive fine gray vermiculations – hard to see in the field, though is does occasionally give the flanks a ‘clouded’ appearance.

Back Pattern

The back and scapulars of adult males in both species are finely barred with black and white zigzags, which blend to a pale gray when seen at a distance. These White markings are finer (not as wide as the black ones) in Greater.
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The back and scapulars average heavier and coarser barring on adult males – the White barring is wider than the black.
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