MEXICAN DUCK 
ANAS DIAZI Ridgway 
(Plate 22) 
Synonymy 
Anas ohscura Lawrence {nec Gmelin), Mem. Boston Soc. Nat. Hist., vol. 2, p. 314, 
1874. 
Anas diazi Ridgway, Auk, vol. 3, p. 332, 1886. 
Veenaculae Names 
English: Mexican Duck, Diaz’s Duck. 
Spanish: Pato triguero. 
DESCRIPTION 
Adult Male : From Anas ruhripes this species can be told by the broader and more fulvous edging of 
the feathers of the mantle and scapulars, and by the presence of a broad white wing-bar both in 
front of and behind the speculum. From Anas fulvigula, which it more nearly resembles, it can be 
told by the white speculmn-bars, by the generally darker and more uniform appearance of the back 
and scapulars, and by the absence of a black area at the base of the culmen. From the male Mallard 
in eclipse plumage it is easily distinguished by its darker under parts. The wing, especially the 
speculum, is almost exactly like that of the Mallard. 
From the female Mallard this species is easily separated by its much darker and more heavily 
mottled under parts, which are the same shade all the way from neck to vent. 
Iris brown. Bill bright yellow. Tarsus light orange to coral-red color. 
Wing 270-285 mm.; tarsus 43-48; culmen 50-53. 
Adult Female: Similar to male but with a more streaked, and less spotted pattern on lower side, 
this difference being due to a different feather-pattern on breast and abdomen. 
Iris brown. Bill orange with dusky markings, nail black. Tarsus dull orange. 
Size smaller than male. W'ing 240-260 mm., average 246; tarsus 40-46, average 43; bill 48-53, 
average 51. 
First (Juvenal) Plumage of both Sexes : Streaked on lower parts like the adult female, and with 
soft parts duller in tone. Anterior white wing-bar not so clearly defined nor so broad. Tail 
feathers blunt. 
Note: A large series of immature and female specimens shows that young at this stage are 
extremely difficult to separate from young Mallards of the same age, but the lower parts are 
as a rule somewhat more thickly streaked with a darker brown color. Size small. 
Young in Down: No specimens available. 
