GADWALL 103 



Gadwall 

 Chaulelasmus streperus (Linnaeus) 



Other names — Gray Duck; Gadwell; Anas strepcra. 



Description — Adult male: Whole head and neck pale brown finely mottled 

 with black, the brown being darkest on top of head with less distinct spotting; 

 throat very pale brownish gray minutely flecked with dusky; bill bluish black; 

 iris reddish hazel; back and sides with fine undulating, transverse bars of 

 brownish black and white; outer surface of closed wing ashy brown with a 

 chestnut patch on middle wing coverts followed behind by a black bar; 

 speculum pure white; rump dull slate color; upper and lower tail coverts 

 velvety black; tail drab gray faintly edged with whitish; whole breast 

 mottled in intricate pattern with crescentic bars of black and white, with a 

 suffusion of pale brown; rest of under surface pure white, save for faint dusky 

 barring in the region of the vent; sometimes a strong suffusion of rusty over 

 whole lower surface; feet dull orange yellow with dusky webs. Total length 

 "19.25-21.75" inches (489-553 mm.) (Eidgway, 1900, p. 95); folded wing 

 9.75-10.90 (248-277); bill along culmen 1.63-1.78 (41.4-45.3); tarsus 1.53-1.67 

 (38.8-42.4) (ten specimens). Adult female: Head and neck colored as in 

 male, but otherwise decidedly different; upper surface and sides coarsely and 

 irregularly barred and mottled with dark brown and dull white; wing as in 

 male but with markings less clean and chestnut entirely lacking; rump and 

 upper and under tail coverts brown, the latter mottled with dull white like 

 flanks; breast heavily mottled with black on a rusty brown ground; lower 

 breast and abdomen white often more or less obscured with rusty. Total 

 length "about 18" inches (457 mm.) (Ridgway, loe. cit) ; folded wing 9.62- 

 10.12 (244-257); bill along culmen 1.52-1.70 (38.6-43.2); tarsus 1.42-1..58 (36.1- 

 40.2) (nine specimens) ; all from California. Eclipse plumage of male: Top of head 

 brownish black with a greenish tinge; indistinct dark brown streak through eye; 

 rest of head and neck dull brownish white marked with blackish brown as in 

 regular plumage; back, rump and upper tail coverts, blackish brown, each 

 feather margined with rusty red; wings and tail as in regular plumage; breast 

 dull rusty red with central black spot on each feather; flanks dark brown 

 broadly marked and margined with dull rusty brown; rest of under surface 

 dull white with a blackish brown spot in center of each feather (see Sharpe and 

 Dresser, in Baird, Brewer and Ridgway, 1884, I, p. 506). Juvenile plumage 

 (both sexes): Closely resembles that of adult female. Natal plumage: Top 

 of head and line from bill through eye, dull brown; sides of heail and neck, 

 dull creamy buff; spot over ear, dusky; upper surface of body dark brown; 

 paired spots on hind margin of wing and sides of rump, light buff; throat 

 and foreneck pale buff; under surface of body buffy white; band across chest 

 buff. 



Marks for field identification — Slender appearance, long pointed wings, 

 general gray coloration, and pure white speculum (the only river duck so 

 marked). Under tail coverts black in male. 



Voice — In flight, an oft repeated "quack," resembling that of the Mallard, 

 though higher pitched and less in volume (Eaton, 1910, p. 189). 



Nest — In grass on dry ground but usually close to water ; composed of grasses 

 and tules and lined with down; resembles that of Mallard. 



Eggs — 7 to 13, bluntly ovate, or nearly oval, measuring in inches 2.02 to 2.18 

 by 1.48 to 1.57 (in millimeters, 51.5 to 55.5 by 37.5 to 40.0), and averaging 



