1 88 THE MIGRATIONS OF BIRDS 



killed near Dos Palos, in Merced County, California, 

 on October i6. A part of the pintails from Utah 

 travel to the Plains region east of the Rocky Moun- 

 tains by routes not easily understood. Evidence at 

 hand indicates a flight to the northward to the head 

 waters of the Missouri River, and south over the 

 Great Plains, since one marked bird was killed in 

 eastern Montana, one in the sand-hill region of 

 Nebraska, and another near the Gulf Coast of 

 Texas. In spring flight several of these banded 

 birds have been taken in Oklahoma, Kansas, Mis- 

 souri, and Saskatchewan, indicating a flight north 

 through the Plains region, in which the birds do not 

 recfoss the mountains to the Great Basin. 



From the evidence presented it seems that ducks 

 concentrate in the Salt Lake Valley, and from there 

 spread in migration over the entire western half of 

 the United States. The region is highly important 

 in the life of many species, so that it is unfortunate 

 that, because of man's diversion of water from 

 streams for purposes of irrigation, the bays inhabited 

 by waterfowl in certain years become polluted with 

 alkalis, so that ducks die there by the tens of thou- 

 sands. 



Interesting data on the movements of ducks from 

 other regions are available through records assem- 

 bled by F. C. Lincoln from banding operations under 

 the Biological Survey. Of these, there may be 



