COWBIRD. 107 



on the upper edge, but could never have been hatched. At 

 times I think it probable that they lay in the nests of larger 

 birds, who throw out the egg, or that they drop their eggs on 

 the ground without obtaining a deposit, as I have found an egg 

 of this kind thus exposed and broken. On placing an egg of 

 this bird in the Catbird's nest it was almost instantly ejected ; 

 and this would probably be the usual fate of the strange egg if 

 the diminutive nurses, thus wisely chosen, were capable of 

 removing it. 



The most usual nurse of this bird appears to be the Red- 

 eyed Vireo, who commences sitting as soon as the Cowbird's 

 egg is deposited. On these occasions 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 3 of her own, with 

 that of the intruder. From the largeness of the strange egg, 

 probably the nest immediately feels filled, so as to induce the 

 nurse directly to sit. This larger egg, brought nearer to the 

 body than her own, is consequently better w-armed and sooner 

 hatched ; and the young of the Cowbird, I believe, appears 

 about the 12th or 13th day of sitting. The foundling is very 

 faithfully nursed by the affectionate Vireo, along with her own 

 brood, who make their appearance about a day later than the 

 Troopial. From the great size of the parasite, the legitimate 

 young are soon stifled, and, when dead, are conveyed, as usual, 

 by the duped parent to a distance before being dropped ; but 

 they are never found immediately beneath the nest, as would 

 invariably happen if they were ejected by the young Troopial. 

 In the summer of 1S39 I actually saw a Chipping S])arrow car- 

 rying out to a distance one of its dead young thus stifled ; and 

 a second nest of the same species in which 3 of its own brood 

 were hatched soon after the Cow Troopial : these survived 2 or 

 3 days, and as they perished were carried away by the parent 

 bird. As far as I have had opportunity of observing, the 

 foundling shows no hostility to the natural brood of his nurses, 

 but he nearly absorbs their whole attention, and early displays 

 his characteristic cunning and self-possession. When fully 

 fledged, they quickly desert their foster- parent, and skulk 



