LIFE HISTORIES OF NORTH AMERICAN WILD FOWL. 197 



swimming for long distances under water, using its wings for this 

 purpose; if pursued it comes to the surface only for an instant, diving 

 again promptly and swimming away so far and so swiftly as to dis- 

 tance its pursuer; it hardly pays gunners to chase the crippled birds, 

 as they are tough and hard to kill, as well as skillful divers; well- 

 trained retrievers have been taught that it is useless to attempt to 

 catch them. The canvasback can dive to great depths and is said to 

 be able to obtain its food at a depth of from 20 to 25 feet. 



Mr. Thomas Mcllwraith (1894) noted a peculiarity in its diving 

 habits, which is decidedly grebelike: 



Before going under water it throws itself upward and forward, describing a curve 

 as if seeking to gain impetus in the descent, just as boys sometimes do when taking 

 a header off a point not much above the water level. 



The vocal performances of this species are not elaborate nor are 

 they frequently heard. The male has a harsh, guttural croak or "a 

 peeping or growling note. The female canvasback can quack almost 

 as well as the black duck, and also gives voice to screaming currow 

 when startled," according to Eaton (1910). 



Fall. — The fall migration route of the canvasback from its main 

 breeding grounds on the central plains of Canada is peculiar and in- 

 teresting, as it has shown some marked changes within recent years; 

 it has always been somewhat fan-shaped, spreading out in three 

 directions; the two main flights have been, in a general way, south- 

 eastward to the Atlantic coast from Delaware southward, and south- 

 ward through the Mississippi Valley to the Gulf of Mexico ; a third 

 line of flight of less importance takes a more southwesterly course to 

 Mexico and the Pacific coast. There is also a southward flight along 

 the Pacific coast of birds which have bred in British Columbia and 

 Alaska. During recent years canvasbacks have been increasing in 

 abundance, during the fall migration, in the vicinity of the Great 

 Lakes, in New York and in southern New England, indicating a more 

 northerly range or a more directly eastward migration route to the 

 Atlantic coast. Previous to 1895 records of this species in Massachu- 

 setts were exceedingly scarce and it was regarded as very rare or a 

 mere straggler; during the next few years records became more fre- 

 (|uent and since 1899 there have been records of canvasbacks taken 

 every year, with increasing frequency, until now the bird has become 

 ji regular, if not a common, visitor in certain localities. For a full 

 account of this interesting change in liabits, I refer the reader to Mr. 

 S. Prescott Fay's (1910) excellent paper on the subject in The Auk. 

 Such a marked change in a migration route is not easily accounted 

 for, though several causes may have had their effect in bringing it 

 about. I believe that the principal cause has been the increased 

 population of the Mississippi Valley and the Central West, which has 

 i)rought about the draining and cultivation of many of its former 



