128 NYROCA VALISINERIA 



seen in crippled birds, I doubt whether they are ever so used under normal condi- 

 tions, except perhaps in the splashing dives seen during play. 



The length of the ordinary dive is not very great, depending, of course, on the 

 depth of the water. Mr. F. S. Harper (MS.) timed some on the Athabasca delta and 

 found that they varied from 13 to 19 seconds under water. Thirty seconds is pro- 

 bably the limit, although I have no figures to substantiate this statement. 



Flight. The flight is rapid, perhaps exceeding in speed that of the Red-head and 

 other diving ducks, but estimates placing it at 100 miles an hour must be greatly 

 modified. Recent careful speed measurements by British Army aviation officers 

 place the ordinary speed of migrating ducks at not more than 45 miles per hour. 

 Very likely diving ducks have a more rapid flight than most surface-feeders, but 

 50 to 55 miles per hour is certainly a generous estimate. 



Canvas-backs give the impression of great speed when passing decoys. Often 

 they do not check their flight in the least, but go by at a terrific pace, causing the 

 best shots to shoot behind by many yards, while the left barrel goes unemptied. 

 They migrate in large flocks and on the wing with the sunlight glancing from their 

 white backs and ruddy heads present a splendid spectacle. Although the flocks 

 maintain the same formation as the Red-heads, the birds themselves look much 

 longer and more arrow-like in the air, and they fly more steadily, with less shifting 

 about within the flock. They are usually entirely silent in flight, but the wings of a 

 large company produce a loud, swishing noise, audible at a great height on a clear 

 morning. When going to sea or changing their feeding grounds they get up to a 

 great elevation where they thin out into long wavy lines or blunt angle-shaped 

 flocks. They are very restless and do much "trading about," even when in their 

 permanent winter quarters. Nobody can be sure where their lordships will plan to 

 spend the day or night and they often leave a favorite region for several days, only to 

 return as suddenly. 



Association with other Species. The few straggling specimens which occa- 

 sionally visit our New England ponds are almost invariably alone or in small groups 

 of two or three. They never appear mixed with Lesser Scaup like the Red-heads. 

 On the coastal waters of Virginia and North Carolina Canvas-backs feed with 

 Swans, Geese, Widgeon and Red-heads and at times one may see huge rafts mingled 

 with great swarms of American Coots. When any of these immense congregations 

 of water-fowl takes wing the Canvas-backs soon separate out into flocks of their 

 own. I do not remember ever seeing them mix much with Red-heads in the South. 



Many of the diving ducks are rather closely associated on the nesting-grounds. 

 The rush-beds which the Canvas-back selects are often occupied by Red-heads, 

 Scaups and Ruddy Ducks. The nests are frequently very close together and mixed 



