134 NYROCA VALISINERIA 



44.4 mm. They are easily told from those of other species by their darker color 

 (Bent, 1901-02). 



The incubation period is the same, or at any rate very nearly the same, as the 

 Red-head's, twenty-two or twenty-three days. Mr. Wolfe wrote me that some which 

 he put into an incubator came out in twenty-one days, but artificial heat brings them 

 out a little sooner. Mr. Wormald hatched out some eggs in England, which had been 

 shipped to him all the way from Alberta, and the few that were fertile took twenty- 

 eight days, but this was, of course, an abnormal case in every way. 



During sitting the females usually leave the nest in the warmer hours of the after- 

 noon, at first joining their mates. Soon, however, the males withdraw to other 

 places and see no more of their dutiful partners. They do not start to moult very 

 soon; according to Harper's observations there was a period up to the 10th of July 

 when there seemed to be no change in their appearance. Those which I have had in 

 confinement kept their winter plumage much later than all other ducks, including 

 Red-heads and Scaups, but it is not safe to draw deductions from observations made 

 on captive birds, especially Canvas-backs, because they are rarely in vigorous health 

 when kept in small enclosures. 



Canvas-backs probably breed the first year, although this does not necessarily 

 apply to all individuals. A male bird hatched by Mr. Wolfe of Edmonton, Alberta, 

 was sent to a gentleman at Port Hope, Ontario, where the following spring, when 

 only one year old, it mated with a female Mallard, the union resulting in a brood of 

 seven hybrid ducklings. 



Status. Except for the great decrease noted on the famous shooting grounds 

 of the Chesapeake since the early nineties, the Canvas-back seems to be holding its 

 own rather well. In recent years there is good evidence to show an increase, both in the 

 East and in the West, and it seems to me that this duck has responded to increased 

 protection better than any other species of diving duck. Drainage and agriculture 

 are continually advancing over the breeding grounds, which results in the complete 

 disappearance of many ponds and the gradual lowering of the water in many others. 

 The whole water-table seems to be sinking in much of the wheat country of North 

 Dakota, but, on the other hand, the Canvas-back's breeding range extends well to 

 the north which is a fact of the highest importance to its future. 



On the once-famous marsh at Monroe, Michigan, great bags were formerly 

 brought in during the autumn flight between the years 1895 and 1901. During that 

 time the "Cans" exceeded the Red-heads by a wide margin and comprised about 

 16% of all the ducks shot. It is interesting to note that during the same period only 

 half as many "Cans" as Red-heads were shot during the spring months. Both these 

 species together were outnumbered five to one by the Scaups at this season. This 

 marsh has long since been ruined by the extension of the city of Monroe. 



