BIRD-NESTING IN ARGENTINA 371 



brown. Judging from the material at hand I should say 

 that there is a characteristic type of marking running 

 through the eggs of the species if we except the two ex- 

 tremes, viz., those almost unspotted, and those so entirely 

 covered with heavy blotches that they appear to be of a 

 uniform chocolate color. 



However, the eggs of each individual seem to vary in 

 some respect from those of any other, as it is impossible 

 to find two exactly alike in comparing series from different 

 places. Frequently, two or more eggs found in the same 

 nest resemble each other so closely in size, shape, and colora- 

 tion, that I think it reasonably safe to say that they were 

 laid by the same bird. 



The nests of the smaller birds contained from one to four 

 eggs of these parasites, in addition to those of the rightful 

 owners. On January 12, I opened an oven-bird nest and 

 was surprised to find fifteen cowbirds' eggs in the dark in- 

 terior. This I considered a record, but Boyle brought one 

 in on the same day containing twenty-six of the speckled 

 eggs. In the days that followed, we discovered numerous 

 "sets" of from ten to twenty. The nest that contained 

 the final record number was found January 16, it contained 

 thirty-eight eggs one of the oven-birds and thirty-seven 

 of the cowbirds. 



Later, we again met these old acquaintances wintering 

 in the rice-fields and rush-grown marshes of Tucuman. 



The white ani (Guira guira) or Guiraca, first seen near 

 Asuncion, and later in Bolivia, was plentiful at Rosario 

 de Lerma. The bird was usually found in small flocks and 

 fed on the ground. 



We found several of their nests near Rosario de Lerma. 

 They were large, loosely built of sticks and placed in the 

 crotch of a cactus or other thorny plant, at no great height 

 from the ground. However, the nest is not conspicuous 

 in spite of its size. 



Pablo Girard, an Argentine naturalist, informed me that 

 these birds frequently nest in communities and that a 



