182 
OMNIVOROUS BIRDS. 
Mr. C. Pickering, found two nests of the Blue-eyed Yel- 
low-warbler, in which had been deposited an egg of the 
Cow-bird previously to any of their own ; and unable to 
eject it, they had buried it in the bottom of the nest and 
built over it an additional story ! I also saw, in the 
summer of 1830, a similar circumstance with the same 
bird, in which the Cow-bird’s egg, though incarcerat- 
ed, was still visible 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. I have also remarked some- 
times 2 of these eggs in the same nest, but in this case 
one of them commonly proves abortive. 
The most usual nurse of this bird appears to be 
the Red-eyed Yireo, who commences sitting as soon as 
the Cow-bird’s egg is deposited. On these occasions, I 
have known the Yireo 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 im- 
mediately 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 warmed and sooner hatch- 
ed ; and the young of the Cow-bird, I believe, appears 
about the 12th or 13th day of sitting. The foundling is 
very faithfully nursed by the affectionate Yireo, along 
with her own brood, who make their appearance about a 
day later than tho Troopial. From the great size of the 
parasite, the legitimate young are often stifled, and, when 
dead, are conveyed, as usual, by the duped parent to a dis- 
tance before being dropped ; but they are never found im- 
mediately beneath the nest, as would invariably happen 
