Species, Age and Sex Identification of Ducks Using Wing Plumage

Gadwall

Sex Determination of Adults

Greater, middle, and some lesser coverts of adult males are mostly either black or cinnamon. On adult females, black and cinnamon feathers are much restricted to the posterior three or four rows of coverts. Tertials of adult males are long, acutely pointed, silver-gray without edging or tipping. Those of adult females are much shorter, more bluntly pointed, and silver-brown with cream colored tips. Greater tertial coverts of adult males are part black and part gray, rarely with traces of white tipping. Those of adult females are similar but usually well tipped with white. Marginal coverts of adult males are without edging but have arcs of narrow vermiculation. On adult females, these feathers are similar to the lesser coverts and often have edging but may be either plain or with wide internal bars or arcs. Post humerals of adult females usually have cream edging at their tips. Those of other ages and sexes do not have this edging.

Sex Determination of Immatures

Tertials of both sexes are short, bluntly pointed, and often frayed at their tips. They are quite similar to those of adult females. In late fall, they may be replaced by sexually dimorphic adult-type tertials. Greater tertial coverts of both sexes usually appear part black and part gray and are tipped with cream. They are narrower and more pointed than those of adults. Greater, middle, and some lesser coverts of immature males have some black and/or cinnamon in three or more rows. Immature females usually have little or no cinnamon color and black is often restricted to two rows of coverts. Some males show arcs of narrow vermiculation. Both sexes may show pale barring, which is usually wider on females. Notch-length measurements are useful to identify immatures by sex, as long as the shafts of the primary feathers have hardened. In 90 percent of the specimens measured, immature male notch-lengths were equal to or greater than 255 mm., while those of immature females were less than 255 mm.

Wing Character	Male		Female
	Adult	Immature	Immature	Adult
Scapulars	Vermiculated or barred or both		Barred
Tertials	Long, acutely pointed; silver- gray; without edging tips not frayed or faded	Small; brownish; bluntly pointed; usually frayed and faded near tips; often pale-tipped		Shorter; bluntly pointed; gray- brown with cream-colored tips which are not frayed or faded
		After molt: Similar to adult male	After molt: Similar to adult female
Greater, middle, and lesser secondary coverts	Cinnamon color present on half the wing; black on three or more rows (if covert bases are considered)	Cinnamon color in one or more rows; some black in three rows; brown coverts narrowly edged with dirty white and with fine central (often arc- shaped) markings	Cinnamon color absent or on covert edges only; black usually on two rows only; brown coverts well edged with dirty white and with coarse central markings	Cinnamon color usually present; black in two or more rows; brown coverts usually well edged and with coarse internal variable markings
Greater tertial coverts	Bluntly pointed; outer webs black; inner webs gray, rarely with traces of white tipping; not frayed or faded	Somewhat pointed; outer webs black; inner webs brown; often frayed and faded at tips		Broadly rounded; usually with white tipping; outer webs black or brown; inner webs brown; not frayed or faded
		After molt: Similar to adult male	After molt: Similar to adult female
Marginal coverts	Usually with arc-shaped vermiculation	Often arc-shaped vermiculations; otherwise without brown pattern	Brown without pattern	Brown without pattern
Post humerals	Broad, rounded, tips without edging	Narrow; pointed; tips without edging		Broad rounded tips, usually light edging
Notch-length	95% > 262 mm.	90% > 255 mm.	90% < 255 mm.	92% < 262 mm.

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