SAND DUNES AND SALT MARSHES 



greatly in numbers but are still abundant 

 throughout the winter, while in the spring 

 they again increase. In the early autumn all 

 these mergansers appear to be in the modest 

 dress of the female and young,— brown heads, 

 ashy gray backs and white breasts. Towards 

 the end of November it is evident that some 

 of them, perhaps a quarter, are changing into 

 the beautiful dress of the adult drake, while 

 by the last of December and throughout Jan- 

 uary and February it is very rare to see a bird 

 in female attire. In March the females put in 

 an appearance, and courting begins, and by 

 the last of April and in May the birds are 

 largely paired, although flocks of either or 

 both sexes are common. Both the drake and 

 the duck have crests, but while that of the 

 duck is dull brown, the crest of the drake is 

 colored like the whole of his head and neck, 

 a dark metallic green. The drake has also a 

 white ring around his neck and a band of red- 

 dish brown streaked with black on his breast, 

 while his flanks and wings show much more 

 white than is to be seen in the duck. His bill 

 is colored red. 



The explanation of the seasonal distribu- 

 tion is interesting. It is evident that the great 



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