Species, Age and Sex Identification of Ducks Using Wing Plumage

1.	Upper wing: primaries, secondaries, tertials, and their coverts: all an unpatterned black or dark brown to gray-brown	Go To 2
1.	Upper wing: primaries, secondaries, tertials, and their coverts not uniform in color or pattern	Go To 6
2.	Notch-length 155 mm. or shorter; primaries strongly curved ventrally; some underwing middle coverts white	Ruddy duck
2.	Notch-length 180 mm. or longer; primaries only slightly curved ventrally; underwing coverts uniformly dark	Go To 3
3.	Outermost primary black with inner web narrowing to about 5 mm. for approximately 70 mm. from its tip; or dark brown and about half the width of adjacent primaries	Black scoter
3.	Outermost primary black, brown or blue and approximately the same width as adjacent primaries	Go To 4
4.	Outerweb of next to outermost primary narrows abruptly 30 mm. to tip; tertials solid black or dark brown (usually with a reddish cast) and narrow light edging	Oldsquaw (part)
4.	Outerweb of next to outermost primary tapers gradually over length; tertials blue, black, or brown	Go To 5
5.	Outermost primary as long or longer than the next primary; notch-length 212 mm. or longer	Surf scoter
5.	Outermost primary varies from longer to shorter than next primary; often bluish: notch-length 203 mm. or shorter	Harlequin duck (part)
6.	Some secondaries part blue, green, or purple	Go To 7
6.	Secondaries not blue, green, or purple	Go To 16
7.	Some secondaries all or part blue or purple	Go To 8
7.	Some secondaries part green	Go To 12
8.	Blue bordered front and back by white on both the greater coverts and the trailing edge of the secondaries	Go To 9
8.	Blue bordered front or back (not both) with white	Go To 10
9.	Tertials straight, brown with light edging, or reddish brown grading into silver-gray; underwing white	Mallard
9.	Tertials curve outward, usually blue; middle and lesser coverts white or brown; underwing part dark	Steller's eider
10.	Greater, middle, and lesser coverts brown; tertials longer than secondaries; underwing white	American black and Mottled ducks 1
10.	Greater, middle, and lesser coverts blue or bluish; tertials approximate secondaries in length; underwing not white	Go To 11
11.	Trailing edge of secondaries white; underwing barred	Wood duck
11.	Trailing edge of secondaries dark; underwing dark	Harlequin duck (part)
12.	Middle and lesser coverts blue	Go To 13
12.	Middle and lesser coverts not blue	Go To 14
13.	Primary shafts white; notch-length 210 mm. or longer	Northern shoveler (part)
13.	Primary shafts brown; notch-length 205 mm. or shorter	Blue-winged & cinnamon teals
14.	Greater coverts banded with cinnamon; trailing edge of secondaries banded with white; outerweb of most distal tertial longitudinally striped with black or brown	Go To 15
14.	Greater coverts banded with black; trailing edge of secondaries banded or unbanded; outer web of most distal tertial white or whitish	American wigeon (part)
15.	Notch-length 200 mm. or less	Green-winged teal
15.	Notch-length 240 mm. or more	Northern pintail (part)
16.	Three or more secondaries white or whitish	Go To 17
16.	Secondaries (exclusive of trailing edge or flecking) not white	Go To 27
17.	Some greater coverts black; none white	Go To 18
17.	Some greater coverts are white or partly so	Go To 20
18.	White confined to 3 or 4 secondaries next to tertials; others cinnamon or light edged with internal patterns; underwing white	Gadwall
18.	Most secondaries white, banded with black near their tips; upperwing covert black or dark brown often flecked with white; underwing partly dark	Go To 19
19.	White of upperwing confined to secondaries	Lesser scaup
19.	White of upperwing extends to primaries	Greater scaup
20.	All upperwing secondary coverts so heavily vermiculated with white as to appear white	Canvasback (part)
20.	Some upperwing secondary coverts not white, none vermiculated	Go To 21
21.	White on secondaries does not reach the shafts; tertials black with central white stripes	Hooded merganser
21.	White extends to the shaft or beyond; tertials black, dark gray, or white with black margins	Go to 22
22.	Tertials black; notch-length 180 mm. or less	Bufflehead
22.	Tertials variable; notch-length 190 mm. or more	Go To 23
23.	Underwing coverts all solid black, gray, or brown	Go To 24
23.	Underwing coverts mostly white; upperwing middle and lesser coverts white, black, or gray	Go To 26
24.	Middle, lesser, and marginal coverts are a uniform black or brown; notch-length 245 mm. or longer	White-winged scoter
24.	Middle and lesser coverts white, or black washed with white or gray; notch-length 240 mm. or less	Go To 25
25.	Black bases extend over more than half of each greater secondary covert	Barrow's goldeneye
25.	Black bases extend over less than half of each greater secondary covert	Common goldeneye
26.	Black bases of secondaries are exposed on a normally spread wing	Red-breasted merganser
26.	Black bases of secondaries are covered on a normally spread wing	Common merganser
27.	Secondaries gray, usually with white tips and a dark sub-terminal band	Go To 28
27.	Secondaries brown or black, without white trailing edge	Go To 29
28.	All upperwing coverts dark brown to black; tertials dark brown to black with faint greenish sheen	Ring-necked duck
28.	All upperwing coverts gray to gray-brown, may vary from plain to heavily flecked and/or vermiculated with white; tertials vary from gray-brown with or without flecking to white well vermiculated with dark gray	Redhead or canvasback (part)2
29.	Secondaries black or mostly so	Go To 30
29.	Secondaries brown or brownish	Go To 34
30.	Tertials white or mostly so	Common eider (part)
30.	Tertials black, olive, or mostly brown	Go To 31
31.	Tertials black	Go to 32
31.	Tertials olive or mostly brown	Go To 33
32.	Tertials sharply curved; middle and lesser coverts black, black and white, or white	King eider (part)
32.	Tertials straight; upper wing black with most coverts washed with dark cinnamon; underwing entirely black	Fulvous whistling duck
33.	Tertials olive; bases of primaries and secondaries white; underwing black	Black-bellied whistling duck
33.	Tertials mostly brown; outer web of most distal white; pale barring on underwing	American wigeon (part)
34.	Primary shafts white; underwing white	Northern shoveler (part)
34.	Primary shafts brown; underwing dark and/or heavily barred	Go To 35
35.	Trailing edge of secondaries white; greater coverts light edged	Go to 36
35.	Trailing edge of secondaries washed with buff	Go To 38
36.	Tertials brown, longitudinally striped, and pale edged	Northern pintail (part)
36.	Tertials brown, edges washed with cinnamon	Go To 37
37.	Tertials sharply curved	King eider (part)
37.	Tertials slightly curved	Common eider (part)
38.	Middle and lesser coverts dark brown with some well-defined buff edging	Common eider (part)
38.	Middle and lesser coverts dark brown well washed with pale buff	Oldsquaw (part)

¹Mottled ducks occur only in southern Florida and the Gulf coast west to include Texas. American black ducks are rare in this area.
² The specula of all redheads are recognizably lighter gray than those of adult female and both sexes of immature canvasbacks.