50 



MIGRATION ROUTES AND F L Y w A Y s 



eastern Nebraska and western Missouri and Arkansas, it merges im- 

 perceptibly into the Central flyway. Nevertheless, a boundary line may 

 be drawn with reasonable accuracy from southern Saskatchewan, across 

 northeastern Montana, thence southeastward along the Missouri River to 

 western Missouri and across western Arkansas and northwestern Louisi- 

 ana to southeastern Texas. 



Easily the most important migration route of this flyway is the long 

 lane of travel that starts on the Yukon Flats in Alaska, traverses the 

 valley of the Mackenzie River, and the great lake and prairie region of 

 central Canada, receiving 

 many accretions on the way, 

 and in turn contributing to 

 other flyways. Running gen- 

 erally from northwest to 

 southeast, it enters the United 

 States on a broad front from 

 Montana to Wisconsin but 

 tends to constriction as it pro- 

 ceeds southward, so that in 

 central Arkansas it results in 

 heavy concentration. This 

 might be termed the "Mallard 

 route," although it is used 

 also by large numbers of Pin- 

 tails and Canada Geese and 

 by lesser numbers of several 

 other shoal-water species. The 

 Ring-necked Duck likewise 

 concentrates on this route, as 

 do some of the Lesser Scaups 

 and a few other deep-water 

 ducks. Coming in from their 

 breeding grounds in western 



Ontario and Michigan and FIG. M.-Thc Mississippi Flyway 



from Wisconsin an Minne- 

 sota, a considerable body of 



Black Ducks proceeds across Illinois by way of the Illinois River. An- 

 other contingent of this species, together with a good representation of 

 Canada Geese, comes in from the northeast. These latter birds, from 

 breeding grounds in western Quebec and Ontario and from Michigan, 

 leave their companions bound for the Atlantic coast in the general 

 vicinity of western Lake Erie, and, proceeding across northwestern Ohio 

 and through Indiana, reach the Mississippi Valley near the mouth of the 

 Ohio River. 



The features of particular significance in this flyway are the vast 

 areas of breeding territory that are tributary to it and the greatly re- 

 stricted winter quarters. These factors result in a heavy concentration 



