Reports of Special Agents 



309 



sible to subdivide these large nesting-places into given areas, for the purpose 

 of enumerating the eggs. 



The three large areas were accordingly subdivided into ten smaller areas. 

 The number of square feet in each was next determined. Likewise, in each 

 of the ten areas, several smaller areas containing ten square feet were marked 

 off at random, and the number of eggs in each of these was actually counted. 

 These separate counts were then averaged, thus giving a fairly representative 







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NODDY TERN ON NEST, DRY TORTUGAS, FLORIDA 



figure for the number of eggs per square toot. Knowmg the number of square 

 feet 'in the area as a whole, the estimate of the total number of eggs contained 

 in it could easily be made. When this same procedure had been followed with 

 respect to each of the ten areas, the total number of eggs was found to be 9,429. 

 Since the birds usually lay but one egg and there are two adults attached to each 

 nest, the total number of Sooties reaches 18,852. This, certainly, is not an 

 excessive valuation. The group photographs (reproduced by permission of the 

 Carnegie Institution) taken upon one of the areas most numerously supplied 

 with eggs, give a fairly correct notion of how thickly the birds are packed 

 together. 



