CANVAS-BACK 245 



The food of the Canvas-back is about four-fifths vegetable matter. 

 An analysis of the stomach contents of 427 of these ducks, taken in 25 

 states, Alaska, and 5 Canadian Provinces, and during every month in 

 the year except July and August, gave the following approximate per- 

 centages: pondweeds, 30; wild celery, 9; delta duck potato, 8; grasses 

 8 (including wild rice, 5); sedges, 6; banana water lily, 4; burr reeds, 

 water milfoils and muskgrass, 6; miscellaneous plant food, 10; total vege- 

 table food, 81 per cent. Molluscs, 9; insects, 8; fishes, 2; total animal 

 food, 19 per cent. As an indication that the Canvas-back is often a glut- 

 ton, it was found that as many as 23 species of food were consumed by 

 one bird at a single meal. On the other hand, indicating that when a 

 satisfactory food is found it is often taken in quantity, and exclusively, 

 it was found that 18 per cent of the birds had made their entire meal on 

 only one species, 14 per cent on a single plant, and 4 per cent on a single 

 animal. The Canvas-back will often dive to depths of 20 and 30 feet in 

 its search for food. 



"While feeding on Vallisneria (wild celery) the Canvas-back is 

 often accompanied by other species of ducks which appreciate the same 

 food, such as the Redhead, Baldpate, and Scaup Duck; the Redhead and 



Scaup can dive almost as well as the 

 Canvas-back and so succeed in pulling 

 up the roots for themselves; but the 

 Baldpate has to be content with the 

 parts discarded by the Canvas-back or 

 with what it can steal by force; the 

 Baldpate frequently lies in wait for the 

 Baldpate robbing Canvas-back Canvas-back and, as soon as it appears 



on the surface with a bill full of choice 



roots, attacks it and attempts to steal what it can; the American coot 

 also persecutes the Canvas-back in the same way" (Bent, 1923). 



The courtship antics of the Canvas-back, condensed from an account 

 by Dr. A. A. Allen, quoted by Bent (1923), is as follows: Several pairs 

 of these birds were observed while gathered on a pond. The males started 

 the performance by uttering their courtship cry of ik, ik, cooo and by 

 swimming around the females, which had gathered in a little group 

 heads together and breasts almost touching. Accompanying their fre- 

 quently repeated calls the males would jerk their heads right back to- 

 ward their tails, or alternatively stretch their heads and necks out along 

 the surface of the water. When uttering their ik, ik, cooo's the backs 

 of the necks would swell, the feathers rise, and the chins bulge out for an 

 instant into a curious lump about the size of a marble. The females re- 

 sponded with low guttural cuk, cuk's. 



The Canvas-back usually nests in the bulrushes and reeds of west- 

 ern sloughs and swampy areas. Its nest is generally cleverly concealed 

 and is usually placed just clear of high-water level. It is an exception- 

 ally large, well-built structure, made of dried reeds, flags and sedges and 

 copiously lined with down. The colour of the down varies from "hair 



