BIRD GENEALOGY 



pushing north of the Savannah sparrows, and 

 their extension to the great sandy wastes that 

 fringed the coast for miles. As the land sank 

 and the waters rose, restricting these regions 

 of sand, the struggle for life among the clan 

 that preferred the sand dunes must have been 

 intense, and it is probable that the larger and 

 stronger ones, as well as those that more 

 nearly matched in color, their surroundings 

 were the more likely to survive. Isolation 

 finally aided in the work, and at last a dis- 

 tinctly new species was evolved, a bird larger 

 than the Savannah sparrow of the mainland, 

 and of a gray or sandy rather than a black and 

 brown color, so that when it squatted in terror 

 on the sand the sailing hawk was more apt to 

 pass it by. 



It seems to me that the evolution of the 

 Ipswich sparrow is, therefore, comparatively 

 recent, and that the age of this species ma}^ 

 be counted by the paltry fifty thousand years 

 or so that have elapsed since the glacial pe- 

 riod. 



Evolution is to classification what the cov- 

 ering of flesh is to the skeleton of a bird; 

 remove either one or the other and we have 

 nothing left but the dry bones. 



301 



