figure II. — Distribution and migration of the rose-breasted grosbeak. 

 Though the width of the breeding range is about 2,500 miles, the 

 migratory Jines converge until the boundaries are only about 700 

 miles apart when the birds leave the United States. For migration 

 paths of other widths see figures 9, 1 0, and 1 2. 



the breeding range (fig. 12). These birds, however, cross all parts of 

 the Gulf of Mexico and pass from Florida to Cuba and Haiti by way of 

 the Bahamas, so that here their route has a width of about 2,500 miles. 



The flyways 



In 1935, as a result of studies of banding data, the author discovered 

 the existence of the four great flyway systems. This discovery, based 



46 



