BIBD BANDING LINCOLN 



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migration they separate and each group adheres to its ancient fly- 

 ways. The proof of this lies in the fact that very few ducks banded 

 in the United States east of the one hundredth meridian (central 

 North Dakota, South Dakota, and Nebraska, western Kansas, and 

 central Texas) are killed west of this line while in the United States, 

 and vice versa. 



Figure 1. — The autumn migration of mallards from Alberta. Each large spot indi- 

 cates the point of recovery of a banded duclj while the shading shows the relative 

 density of the flight iu the different regions 



The significance of this discovery will be more readily understood 

 by reflecting upon the present condition of our wild waterfowl. Dur- 

 ing recent years drought conditions, disease, overshooting, and other 

 unfavorable factors have been disastrous to these birds, chiefly those 

 inhabiting the western part of the country. Some species (notably 

 the diving ducks) that visit the eastern district have also been seri- 



