164 THE COW BLACKBIRD. 



This species has never been known to build a nest, nor to take 

 any interest in raising its young, which are left entirely to 

 the care of foster parents. Almost invariably the nest of a 

 bird much smaller than itself is chosen. The Sparrows, the 

 Warblers, the Vireos, the smaller Fly catchers-^ in- fact, any 

 of the small land-birds — may become the victim of this im- 

 position. Occasionally birds near its own size, as the 

 Scarlet Tanager or the Bluebird, may be obliged to bear 

 the burden. The Cow Bird's egg is so unusually small for 

 the size of the bird, only some 90 x -65 of an inch, that it 

 is readily accommodated in the nests of very small birds, 

 whereas, if dropped into that of larger ones, it may be 

 thrown out, I have found it with a hole in the side and 

 lying on the ground, beneath the nest of the Yellow-breasted 

 Chat, thus evidently pierced by the bill of the bird, and 

 ousted in indignation. These eggs, of a dirty white and 

 specked all over with brown, are readily distinguished from 

 those of any nest in which they may be placed, and are 

 always unwelcome to the owners, which will become very 

 uneasy and querulous; and the female, hunting up its mate, 

 will make a noisy ado over the intrusion. If the owner 

 has not yet laid her own eggs she may forsake the nest, or 

 add a story to it, thus burying the foreign egg so deeply as 

 to suffer no inconvenience from it. Many cases of the latter 

 expediency have been found. Wilson found a Yellow War- 

 bler's nest containing two eggs thus separately built out, mak- 

 ing a nest of three stories. I have seen a like nest of the Red- 

 start. The owner of such a nest does, indeed, deserve " a 

 better fate than that her house should at last be despoiled by 

 a naturalist;'' but "passing thus into history," and making 

 such a contribution to science, is worth a great sacrifice. I 

 once found a Wood Thrush sitting stupidly on a solitary egg 

 of the Cow Blackbird. This would seem to be exceptional. 



