330 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 32 



Table 2. — Banded waterfowl 



Species 



Mallard 



Black duck 



Gadwall 



Baldpate 



Pintail 



Green-winged teal 

 Blue-winged teal . 



Species 



Cinnamon teal — 



Shoveler... -. 



Kcdhead 



Ring-necked duck 



Canvasback 



Lesser scaup 



Number 

 banded 



562 



346 



3,149 



2, 083 



752 



Number 

 of returns 



38 

 63 

 545 

 241 

 100 

 591 



Migration. — Study of the distribution and migration of North 

 American waterfowl continues to be a major project of the Biolog- 

 ical Survey, and as will be noted from the data contained in Table 2 

 the number of banding records applicable to this subject is increas- 

 ing rapidly. 



A detailed investigation of the distribution and migration of the 

 mallard and the black duck, two of the most important species of 

 game waterfowl, is now in progress. Several thousand return rec- 

 ords are at hand, which make it possible not only to present in 

 full detail the intricate movements that make up the semiannual 

 movements of these birds but also to portray graphically the way 

 the flocks sweep across the country. While ornithologists and sports- 

 men have long understood the existence of migration flyways, along 

 which birds are more or less concentrated, there has been a tendency 

 to consider these lines of arterial traffic as narrow lanes, rather than 

 as broad boulevards. The banding records show the general routes 

 followed and also their approximate widths. From a study of these 

 data a new type of migration map (fig. 1) has been devised to illus- 

 trate the advance and spread across the country of the ducks from 

 any particular breeding or concentration area. Several maps of this 

 type will show the movement of a species from different areas, and 

 when these are superimposed on each other the resulting map should 

 present an easily understood picture of the entire migratory flight 

 for that species. 



As will be seen from the map (fig. 1), ducks banded in the Prairie 

 Provinces of Canada, in the autumn move both southeast and south- 

 west. In fact, the great flocks of canvasbacks and redheads that 

 winter on the Atlantic coast come chiefly from the interior breeding 

 ground. 



The banding work earl}^ showed that during the migratory season 

 there is very little interchange of waterfowl between the eastern 

 and the western halves of the country within the United States, even 

 with those species that have a more or less general continental dis- 

 tribution. On the breeding grounds in central Canada the eastern 

 and western ducks intermingle freely^ but when the time comes for 



