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 warmed 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 1839 I actually saw a Chipping Sparrow 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 
