1 82 THE MIGRATIONS OF BIRDS 



period of breeding, during the remainder of the 

 year they are concentrated in favorable areas, where 

 they may assemble in tremendous numbers. In 

 North America the marshes of Great Salt Lake, the 

 interior valleys of California, the delta region at the 

 mouth of the Mississippi River, the estuaries of the 

 Susquehanna and Potomac rivers, and the region 

 of Currituck Sound are all famous ducking grounds. 

 It will be of interest to trace some of the migration 

 routes by which ducks reach these regions. We 

 have available for this study a fair amount of in- 

 formation based on birds that have been banded, 

 so that some of the routes may be traced in some 

 detail. It is interesting to find that a number do 

 not tend in direct north and south Hnes. 



The Bear River marshes at the northern end of 

 Great Salt Lake have been known as one of the 

 famous shooting grounds in the western states, but 

 it was not until data became available from banded 

 ducks that the importance of this region as a 

 centre of distribution was realized. From 19 14 to 

 1 91 6 I was occupied during the months of summer 

 and autumn in studies of the birds of these marshes, 

 and banded some 1200 birds as an incidental part 

 of other work in hand. Returns from these have 

 yielded results of the greatest interest. 



As a preliminary statement, it may be noted that 

 many of the birds captured and banded at this point 



