SEASONAL FLIGHT OF DUCKS 185 



and from the Mexican border to Saskatchewan. 

 (See Fig. 6.) Analysis of the records gives a clue to 

 some of the lines of migratory flight that are pur- 

 sued. By way of introduction, however, it may be 

 stated that ducks are birds of strong flight to which 

 mountain barriers mean little, so that their journeys 

 from the Salt Lake Valley do not necessarily follow 

 uniform trails through the sky. Certain general 

 routes however are indicated. There is one broad 

 fly line that passes south over the Rocky Mountain 

 plateau, used by a comparatively small number of 

 birds, which carries ducks to the scattered lakes 

 and ponds of central and southern Utah, New Mex- 

 ico, and Arizona. To digress for a moment, it may 

 be observed that this line of flight is the one pur- 

 sued by snowy herons from the colonies at the mouth 

 of Bear River; birds of that species, as shown by 

 banded individuals, migrate south through south- 

 ern Arizona, where one was killed on the San Pedro 

 River in Cochise County, to a wintering ground on 

 the west coast of Mexico. Returns from these birds 

 have been interesting. A peon at Mexcaltitan, Ter- 

 ritory of Tepic, found a bit of aluminum on the leg 

 of a heron that he had killed to eat, and brought it 

 to a Japanese labor contractor. The band had been 

 preserved from curiosity, as the peon was unable 

 to read; so that the merest chance brought a return 

 from one of the snowy herons banded the year pre- 



