8 CIRCULAR 3 4 2, TJ. S. DEPARTMENT OF AGRICULTURE 



THE CENTRAL FLYWAY 



As previously stated, the eastern boundary of the Central flyway 

 (fig. 3) merges imperceptibly with the western boundary of the 

 Mississippi flyway, but in general it is bounded in this direction by 

 the Missouri River and by the western parts of Arkansas and Mis- 

 souri. The western boundary appears to start on the north at 

 Great Salt Lake, Utah, and runs southeastward across Utah and 

 western New Mexico. 



Along this flyway sweep flocks of ducks that in the north coun- 

 try share a common breeding ground with others of the same species 

 that follow in migration all the other fly ways. Lying across, the 

 northern terminus of the western boundary is the most important 

 single breeding ground for waterfowl that now remains in the 

 United States — the Bear River Marshes at the northern end of Great 

 Salt Lake, Utah. This is still an important breeding area for pin- 

 tails, redheads, cinnamon teal (Querquedula cyancptera) , and 

 others. A large percentage of the birds raised here follow lanes of 

 travel westward to the Pacific flyway, but it is noteworthy that there 

 are at least three routes that leave this area in an easterly or north- 

 easterly direction. One of these, tributary to the Atlantic flyway, 

 has been described (p. 4). A second easterly route from these 

 breeding grounds extends across southern Wyoming, turns south- 

 ward across the Laramie plains and eastern Colorado, and by way 

 of the Panhandle of Texas ends on the Gulf coast. The third route 

 turns southward in northwestern Colorado, crosses the Uncompahgre 

 Plateau, passes through the San Luis Valley, and extends south- 

 ward into Mexico. 



It is significant that while the Bear River Marshes are an im- 

 portant waterfowl concentration point, where large numbers of 

 ducks are killed each season, it has furnished almost no recovery 

 records of birds banded in Canada. 



With the exception of the tributary routes from the Bear River 

 Marshes, this also is a relatively simple flyway, as the majority of 

 tlie ducks that use it make direct north and south journeys from 

 breeding grounds in central Canada and other northern regions to 

 their winter quarters, which are chiefly in Texas. 



THE PACIFIC FLYWAY 



The Pacific flyway (fig. 4) presents some interesting peculiarities. 

 While the map shows a route that follows the coast of British Co- 

 lumbia, it should be pointed out that this is not an important lane 

 of travel for many of our game ducks, but it is followed chiefly 

 b} r the diminutive cackling goose {Brant a canadensis minima), the 

 black brant (B. nigricans), and some of the sea clucks. The cack- 

 ling geese that breed in the region of the delta of the Yukon River 

 in Alaska follow this route across the Alaska Peninsula and the 

 Gulf of Alaska and along the coast of British. Columbia, and turn 

 into the interior near the mouth of the Columbia River. Proceed- 

 ing eastward only a short distance they again turn south to their 

 winter quarters at the Tule Lake Wildlife Refuge, on the Oregon- 

 California line, and in the Sacramento Valley of California. A 

 few continue southward as far as the northern part of the San 

 Joaquin Valley. 



