2 CIRCULAR 3 42, TJ. S. DEPARTMENT OF AGRICULTURE 



to work out the routes of travel of most species of North American 

 migratory birds. The routes he delineated were necessarily of a 

 more or less general nature, but in some cases he presented the data 

 in remarkable detail. 



At about the time of Professor Cooke's death, in 1916, which was 

 the year the Migratory Bird Treaty with Great Britain was negoti- 

 ated, the study of bird migration by banding was first undertaken 

 by the Bureau. In that year, working in the Bear Eiver Marshes 

 of Great Salt Lake, Utah, Alexander Wetmore attached Biological 

 Survey bands to several hundred ducks, herons, and other marsh 

 and shore birds. Systematic bird banding in North America had 

 been begun in 1909, when the American Bird Banding Association 

 was formed, although 2 or 3 previous projects had been undertaken. 

 The work of this association was taken over by the Biological Survey 

 in 1920 and has continuously developed since that time. Tens of 

 thousands of banded birds have been recovered, each record adding 

 to our knowledge of the travels of migratory birds, and the aggregate 

 permitting a much clearer exposition of the flight lines of the differ- 

 ent species. 



All kinds of native birds are banded, but because of their great 

 importance as game, the migratory waterfowl have been given special 

 attention. Many thousands of ducks and geese that were banded at 

 points scattered over nearly the entire continent have been recovered, 

 and the resulting data have aided materially in the elucidation of 

 many complex .problems of migration. Although the grouping of 

 waterfowl-migration routes was suggested by some of the writings 

 of Cooke, it remained for the banding work more clearly to portray 

 this phase of migration, which forms the subject of this publication. 



MIGRATION ROUTES AND FLYWAYS DEFINED 



The terms " migration route " and " flyway '■' have in the past 

 been used more or less indiscriminately, but for the purpose of this 

 circular and in order that the full picture of migration may be 

 better portrayed, it seems desirable to designate as migration routes 

 the individual lanes of avian travel from breeding grounds to winter 

 quarters, and as flyways those broader areas into which certain 

 migration routes blend or come together in a definite geographic 

 region. The individual migration routes may be likened to long 

 trails, while the flyways resemble shorter arterial boulevards to 

 which the routes are tributary. Except along the coasts, the bound- 

 aries of these flyways cannot always be sharply defined, particularly 

 in the northern part of the interior, for the reason that — broadly 

 speaking — all the country from Nebraska north to the Arctic coast 

 is one great breeding ground that is used by many species of migra- 

 tory waterfowl. From about latitude 45° southward to the Gulf 

 coast, however, these flyways are fairly well marked, and it is 

 within this region that most of the sport shooting takes place. The 

 status of the ducks and geese in the different flyways, therefore, is of 

 great interest not only to naturalists but also to sportsmen. 



It is now a matter of common knowledge that migratory birds 

 follow certain definite routes on their journeys to and from breeding 



