numbers as they pass over the great breeding grounds of central and 

 southern Canada. Upon reaching the headwaters of the Missouri and 

 Mississippi Rivers the route follows these streams to the Gulf coast, 

 Arriving in this latitude many species, including the ducks and geese, 

 the robin, the myrtle warbler, and some others spread out east and west 

 for their winter sojourn. Others, despite the perils of a trip involving 

 a flight of several hundred miles across the Gulf of Mexico, strike out 

 boldly for Central America and South America. This part of the route 

 is a broad "boulevard" extending from northwestern Florida to eastern 

 Texas and reaching southward across the Gulf of Mexico to Yucatan 

 and the Isthmus of Tehuantepec (fig. 17, route 4). In other words, 

 when most of the birds (chiefly shore birds and land birds) that have 

 come south directly through the Mississippi Valley have reached the 

 coastal plains of Mississippi and Louisiana, they continue directly 

 across the Gulf of Mexico. This route appears to have preference over 

 the safer but more circuitous land or island routes by way of Texas 

 and Florida. During the height of migration some of the islands off 

 the coast of Louisiana are wonderful observation points for the student 

 of birds, as the feathered travelers literally swarm over them. 



Present detailed knowledge of the chief tributaries to the Mackenzie- 

 Great Lakes-Mississippi Valley highway relates chiefly to waterfowl. 

 Reference already has been made to the flight of the black ducks 

 (p. 58) that reach the Mississippi Valley from southern Ontario. Some 

 individuals of this species banded at Lake Scugog, Ontario, have been 

 recaptured in succeeding seasons in Wisconsin and Manitoba, but the 

 majority have been retaken at points south of the junction of the Ohio 

 River with the Mississippi, definitely indicating their route of travel 

 from southern Ontario. 



A second route that joins the main artery on its eastern side is the one 

 used by the blue goose, the migration route of which is probably more 

 nearly due north and south than that of any other North American 

 bird. The breeding grounds, which only in recent years have been 

 discovered, are mainly in the Fox Basin region of Baffin Island and 

 on Southampton Island. In fall these geese work southward, chiefly 

 along the eastern shore of Hudson Bay, and upon reaching the southern 

 extremity of James Bay they take off for what is practically a nonstop 

 flight to the great coastal marshes of Louisiana west of the delta of 

 the Mississippi River. In some seasons the flocks make intermediate 

 stops among the islands and sand bars of the Mississippi, as they are 



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