246 BAY, SEA OR DIVING DUCKS 



brown" to drab, and the breast-feathers in the nest are whitish. The 

 encroachment of civilization, with the consequent reclamation of marshy 

 areas, is a serious menace to these and other slough-nesting ducks, which 

 are gradually being forced further and further north to less suitable and 

 less congenial districts, or are being altogether exterminated. Bent (1923) 

 says: "The Canvas-back usually lays from 7 to 9 eggs, but the set is of- 

 ten increased, if not usually so, by the addition of several eggs of the 

 Redhead, Ruddy Duck, or other species. The eggs when fresh can be 

 readily distinguished by their colour, which is a rich greyish olive or 

 greenish drab of a darker shade than that usually seen in the eggs of 

 other species." The average size of the eggs is 2.45 by 1.72 inches. In- 

 cubation requires from 24 to 28 days and is performed entirely by the 

 female. The males desert the females as soon as the eggs are laid and 

 gather into large flocks in the lakes and large open spaces in the sloughs 

 where they proceed to moult into the eclipse plumage. 



When migrating, Canvas-backs fly in large, wedge-shaped flocks at 

 considerable altitude. Tremendous power is expressed in the speed and 

 directness of their driving flight. With long, slender heads and necks out- 

 stretched and with noisy and rapid 

 beating of their sharp-pointed 

 wings, they dash by. They are con- 

 ceded to be the fastest fliers among 

 the ducks and in one instance, while 

 being chased by an aeroplane, were 

 timed at the rate of about 72 miles 

 an hour. On their feeding grounds, 

 long morning and evening "consti- 

 tutional" flights, to and fro, for 

 miles in each direction, are characteristic of the Canvas-backs and Red- 

 heads; a full description of these flights is given in the "Life Story" of 

 the latter bird. 



Canvas-backs in their migrations are to be looked for upon or near 

 the larger bodies of water. During the day the flocks rest well out in the 

 bays but in the early mornings and evenings come closer inshore to feed. 

 The Canvas-back is essentially a diving duck and excels in this regard, 

 often seeking its food in twenty to thirty feet of water. So strong a 

 swimmer it is, that to retrieve a wounded bird is practically impossible; 

 it will swim away for a long distance under water, appearing for a mo- 

 ment, submerging instantly, to appear again far in the distance. When 

 diving, it uses both feet and wings for propulsion. 



The Canvas-back is a wary bird and difficult to approach. In the 

 autumn new arrivals decoy readily, but those that have been in the 

 vicinity for some time avoid the decoys with great cleverness. Like the 

 Redhead, it is a very inquisitive bird, and in times past this weakness 

 was taken advantage of by hunters who used to attract these birds within 

 shooting distance by "tolling" them in. Bent (1923), says: "An in- 

 teresting ancient method of shooting Canvas-backs was by tolling them 



