FOOD HABITS OF SHOAL-WATER DUCKS. 23 



and early in fall. It usually arrives in central Iowa during the last 

 week in March, and at Aweme, Manitoba, about a month later. In 

 the fall migration it reappears throughout the northern half of the 

 United States during the month of August and reaches the Gulf of 

 Mexico about the middle of September. In habits it is very similar 

 to the green-winged teal, and like that bird its numbers have been 

 greatly diminished in recent years on account of its slight fear of man 

 and the consequent ease with which it may be shot by even inex- 

 perienced sportsmen. It is especially rare in most of the States east 

 of the AJleghenies, and great care should be taken in some localities 

 to see that it is not entirely wiped out. 



In general appearance the blue-winged teal is similar to the green- 

 wing, having also a green speculum, which, however, is supplemented 

 by a light-blue shoulder patch, separated from the green by a narrow 

 white line. The adult male also lacks the white mark before the 

 wing, which is present in the green- winged teal, but has a large white 

 crescent on each side of the face In front of the eye. 



FOOD HABITS. 



To determine the food habits of the blue-winged teal, 319 9 

 stomachs were examined, collected from 29 States and 4 Canadian 

 Provinces during a period of 31 years, and in every month but 

 January. As might be expected, the greatest numbers were col- 

 lected in the fall, during the months of September, October, and 

 November, making the average percentages of various kinds of foods 

 for those months more accurate than for the remainder of the year. 

 Rather large series were collected in Wisconsin (58), Florida (46), 

 Maine (40), and North Dakota (36); the remaining stomachs were 

 fairly evenly distributed. The character of the contents of the stom- 

 achs from the States furnishing the largest numbers was not such as 

 to influence unduly the final averages. 



Vegetable Food. 



About seven-tenths (70.53 per cent) of the blue-winged teal's food 

 consists of vegetable matter. Of this about three-fourths is included 

 in four families of plants. Sedges (Cyperaceae) , with 18.79 per 

 cent; pondweeds (Naiadaceae), 12.6; grasses (Gramineae), 12.26; and 

 the smartweeds (Polygonaceae) , 8.22. The remainder of the plant 

 food is made up of algae, 2.95 per cent; waterlilies (Nymphaeaceae), 

 1.37; rice and corn, 0.98; water milfoils (Haloragidaceae), 0.71; 

 bur reeds (Sparganiaceae), 0.38; madder family (Rubiaceae), 0.35; 

 and miscellaneous, 11.92 per cent. 



9 Ninety of these were examined by W. L. MeAtee. 



