62 Observations on the Cow Bunting 



are not much superior in size to those of their intended foster- 

 parents." (Ornithological Biography, i. 496.) 



If this were a fact, it would justly be entitled to the epithet 

 remarkable ; but that this writer is greatly overseen, would be 

 evident by a comparison of the egg of the blue-grey flycatcher, 

 of the chipping sparrow, or of the indigo bird, with that of the 

 cow bunting. The relative size of these eggs would be found 

 to be equal to that of those of the ordinary hen and the turkey. 



Reasoning from this supposition, the author above quoted 

 sagaciously notes " the adaptation of means to ends which 

 nature has so admirably made." " The object," continues he, 

 "has been, to secure the developement of the embryo, by 

 adapting the size of the egg to the capability of imparting 

 heat to it." 



It sometimes happens that a plausible theory is demolished 

 by a single fact. Had our ingenious naturalist bethought 

 him, that the egg of a goose requires no longer term of incu- 

 bation, when placed under a hen, than when under the goose 

 herself; and that, should a hen sit upon her own eggs, mixed 

 with those of a goose, the heat imparted to each kind, although 

 so greatly dissimilar as to size, would be precisely the same ; 

 he would have hesitated before he uttered an opinion which 

 should seem to bespeak a want of knowledge of one of the 

 simplest laws of nature. Every one who has paid the least 

 attention to the breeding of poultry must know that the 

 plumage of a sitting bird, being a non-conductor, forms an oven, 

 the heat of which, although not precisely equal in all its parts, 

 is, nevertheless, rendered equally efficient to all its contents, in 

 consequence of an invariable habit which the bird has of 

 frequently shifting her eggs from the circumference to the 

 centre. 



Mr. Nuttall*, a more discerning naturalist than the one just 

 named, seems at no loss to account for the circumstance of the 

 cow bird's egg being the first hatched : its largeness bringing 

 it nearer to the body of the sitting bird than her own eggs, it 

 is, consequently, better warmed, and sooner hatched ! But 

 let us have his own words : — " The most usual nurse of this 

 bird appears to be the red-eyed vireo, who commences sitting 

 as soon as the cow bird's egg is deposited. On these occa- 

 sions, I have known the vireo to begin her incubation with only 

 an egg of each kind ; and in other nests I have observed as 

 many as three of her own, with that of the intruder. From 

 the largeness of the strange egg, probably the nest immediately 

 feels filed, so as to induce the nurse directly to sit. This 



* A Manual of the Ornithology of the United States, and of Canada. By 

 Thomas Nuttall, F.L.S. 



