162 BIRDS OF ILLINOIS. 



2. A. affinis. Flanks vermiculated or zigzagged with blackish. 



Similar to A. marila nearctica (including absence of distinct white spaces on six 

 inner quills), but black of head in male glossed with purplish, instead of green; 

 length 15.00-16.50, culmen 1.58-1.90. 

 B. Speculum bluish gray. 



3. A. collaris. 



Aythya marila nearctica Stejn. 



AMERICAN SCAUP DUCK 

 Popular synonyms. Big Black-head; Big Blue-bill; Lake Blue-bill; Broad-bill; Bay 



Broad-bill; Baft Duck (Virginia) ; Big Fall Duck (Huds. Bay Terr.); Shutter; Bay 



Shuffler; Troop Dock; Flock Duck (Maryland): Bull-neck. 

 Anas marila WILS. Am. Orn. viii, 1814, 84, pi. 69, flg. 3 (may be F. affinis). 

 Fulioula marila Sw. & RICH. F. B.-A. ii, 1831, 453 (part; includes F. affinis). Ntrrr. Man. 



ii, 1834, 437 (do.). A0D. B. Am. vii, 1813, 355, pi. 498 (not of vi. 1843 316, pL 397. nor of 



his earlier works, which = F. affinis). COUES, Key, 1872, 289; Check List, 1873, No. 



500; ed. 2, 1882, No. 720; B. N. W. 1874, 573. HBNSH. ZooL Wheeler's Exp. 1875, 479. 

 Fulix marila BAIBD, B. N. Am. 1858. 791; Cat. N. Am. B. 1859, No. 588. RIDGW. Orn. 



40th Par. 1877, 625; Nom. N. Am. B. 1881, No. 614. B. B. & R. Water B. N. Am. ii. 



1884.18. 

 Aythya marila nearctica STEJN. Orn. Expl. Kamtsch. 1885, 161. A, O. U. Check List, 



1886. No. 148. RIDQW. Man, N. Am. B. 1887, 103. 



HAB. North America in general, breeding far north; in winter, as far south as Central 

 America and the West Indies. 



SP. CHAE. Adult male: Head, neck, and chest black, the first with a greenish gloss ; 

 back and scapulars white, irregularly waved or vermiculated with zigzag lines of black; 

 wing-coverts dusky, finely grizzled with grayish white ; secondaries white, tipped, and 

 sometimes narrowly edged, with black; tertials black, with a very faint bottle-green reflec- 

 tion; primary-coverts dusky black; primaries similar, but the inner Quills pale grayish 

 on outer webs, except at ends, the gray growing whiter on the shorter feathers ; rump, upper 

 tail-coverts, tail, and crissum, dull black. Lower parts between the chest and crissum white, 

 the posterior portion (and sometimes the sides and flanks) zigzagged with dusky. Bill 

 pale blue (or bluish white) in life, the nail black; iris bright yellow; legs and feet pale slate. 

 Adult female: Head and neck sepia-brown, the anterior portion of the former, all round the 

 base of the bill, white; chest, anal region, and crissum. pale grayish brown, fading gradually 

 into the white of the breast and abdomen ; sides and flanks deeper brown ; above, brownish 

 dusky, the back and scapulars but faintly or not at all grizzled with white ; wings much as 

 in the male. 



Total length, about 18 to 20 inches; extent, 29. 50 to 35.00; wing, 8.25-9.00; culmon, 1.85- 

 2.20; width of bill near end, .85-1.05. at base, .70-.90; tarsus, 1.40-1.60; middle toe, 2.25-2.45. 



While usually, perhaps, only a transient migrant, the Big 

 Black-head not unfrequently passes the winter in the southern 

 portions of Illinois. Its breeding range extends from Manitoba 

 to the Arctic coast. 



Like the Canvas-back, the Black-head is very fond of the 

 roots of the "water celery" (Vallisneria spiralis], and, accord- 

 ing to Dr. Brewer, is one of the very few ducks that are able 

 to dive and pull up these roots. 



