38 Trans. Acad. Sci. of St. Louis. 



Alberta, where most abundant ; northwestward to Sitka. Breeds 

 locally from Minnesota, North Dakota, Colorado and Nevada 

 northward. Winters from Fraser River to Mazatlan and from 

 Chesapeake Bay and the Ohio River southward through the 

 southern states to central Mexico. 



Though not rare the Canvas-back is a less regular transient 

 visitant in Missouri than the Redhead and in smaller troops. 

 It occurs sometimes in February, but mostly between March 1 

 and April 15, and in fall from October 25 to December 10, 

 oftenest from the middle to the end of November. 



148. Aythyamarila (Linn.). Scaup Duck. 



Aythya marila nearctica. Anas marila. Fuligula marila. Fulix marlla 

 Big Black-head. Big Blue-bill. 



Geog. Dist. — Northern hemisphere; in America breeding from 

 Minnesota and British Columbia throughout northwestern Canada 

 to Kotzebue Sound and the Aleutian Islands, more commonly 

 northward. Winters from the Aleutian Islands along the Pa- 

 cific coast almost to Mexico, in the lower Mississippi Valley and 

 abundantly from Long Island to Chesapeake Bay, less commonly 

 along the South Atlantic and Gulf coast to southern Texas. 



Like the Canvas-back, and even more so, the Big Blue-bill is 

 irregular in its appearance in Missouri, and never occurs in large 

 flocks like its smaller cousin. Available dates of its capture on the 

 marshes of northeastern Missouri range from February 28 to 

 April 1 (One taken May 18 was probably a cripple). In fall from 

 November 10 to December 5. 



149. Aythya affinis (Eyt.). Lesser Scaup Duck. 



Fuligula affinis. Fulix affinis. Fuligula mariloides. Fuligula minor. 

 Fuligula marila in Audubon's works. Little Blue-bill. Little Black- 

 head. 



Geog. Dist. — North America, breeding from the northern 

 border of the United States northward through the prairie region 

 to the Arctic Circle, and from Hudson Strait to the Yukon 

 River; rarely in northern United States and on the Pacific coast. 

 It winters in the South Atlantic States and southward to the 

 Greater Antilles ; it is especially common along the Gulf coast to 

 Guatemala; less common in California. 



In Missouri the Blue-bill is a very common transient visitant, 

 occurring in large flocks from the last of February to the middle 

 of April, and from October 1 to December 5. Earliest for St. 



