108 SEA DUCKS. 



bill, as in the AnatiiKe, acts as a sieve or strainer. As a rule they feed 

 by day and pass the night at a distance from the shore or at sea. Some 

 of the species occur in our waters in large flocks — indeed, our most 

 abundant Ducks are members of this subfamily. With one exception 

 they are northern breeding birds, seldom nesting south of our north- 

 ern tier of States. 



Their nest is composed of twigs, leaves, grasses, stems of aquatic 

 plants, seaweed, etc., lined with down from the breast of the incubat- 

 ing bird. 



KEY TO THE SPECIES. 



I. Feathers at tlie base of the bill not reaching -50 forward along its sides. 



A. Wing over 7"00 ; axillars and most if not all the linings of the wings white. 



a. Head and neck black, with greenish or purplish reflections. 

 a^. Back black ; bill with a bluish band near its tip. 



150. EiNG-NECKED DuCK S . 



b^. Back finely barred with black and white. 

 b^. Back of head generally with purplish reflections ; wing generally 

 under 8"25 ; nail of bill generally under -25 in width. 



149. Lesser Scaup Duck $ . 

 J3. Back of head generally with greenish reflections; wing gener- 

 ally over 8'25 ; nail of bill over •25 in width. 



148. Am. Scaup Duck $ . 



b. Head and neck rufous or rufous-brown, sharply defined from the black 

 breast. 



6i. Head and upper neck rich rufous ; bill 2-00 or under ; flanks finely 

 barred, like the back 146. Eedhead $. 



b^. Head and neck rufous-brown ; crown blackish ; bill over 2-00 ; flanks 

 very slightly if at all barred 147. Canvasback $ . 



c. Head and neck brownish or grayish. 

 ci. A white patch in the wing. 



6-2. Feathers at base of bill white ; wing generally under 8-25 ; nail of 



bill generally under -25 in width . . 149. Lesser Scaup Duck 9 . 

 c3. Feathers at base of bill white ; wing generally over 8*25 ; nail of 



bill generally over -25 in width . . . 148. Am. Scaup Duck 9 . 

 d^. No white in wing. 

 d^. An indistinct bluish band near the tip of bill ; bill under 2-00. 



d^. Wing under 8*00 150. Ring-necked Duck 9. 



d*. Wing over 8-00 146. Eedhead 9 . 



e^. No band on bill ; bill over 2-00 " 147. Canvasback 9 . 



B. Wing over 7'00; axillars and most if not all the under wing-coverts 

 blackish. 



a. Head and throat dark steel-blue or steel-green. 

 «!. Head and throat steel-blue; white patch at base of bill 1-00 or more 



in height 152. Barrow's Golden-eye 5 . 



«2. Head and throat steel-green ; white patch at base of bill less than 



I'OO in height 151. Am. Golden-eye $. 



