COW BUNTING. 
299 
and the process of incubation was going on. Three or four 
days after my first visit, I found a young Cow Bird and three 
eggs remaining. I took the eggs out ; two contained young 
birds apparently come to their full time, and the other was 
rotten. I found one of the other eggs on the ground at the 
foot of the stump, differing in no respect from those in the 
nest, no signs of life being discoverable in either. 
“ Soon after this I found a Goldfinch’s nest with one egg 
of each only, and I attended it carefully till the usual com- 
plement of the owner were laid. Being obliged to leave home, 
I could not ascertain precisely when the process of incubation 
commenced ; but from my reckoning, I think the egg of the 
Cow Bird must have been hatched in nine or ten days from 
the commencement of incubation. On my return, I found 
the young Cow Bird occupying nearly the whole nest, and 
the foster-mother as attentive to it as she could have been to 
her own. I ought to acknowledge here, that in none of these 
instances could I ascertain exactly the time required to hatch 
the Cow Bird’s eggs; and that of course none of them are 
decisive; but is it not strange that the egg of the intruder 
should be so uniformly the first hatched ? The idea of the 
egg being larger, and therefore from its own gravity finding 
the centre of the nest, is not sufficient to explain the pheno- 
menon ; for in this situation the other eggs would be propor- 
tionably elevated at the sides, and therefore receive as much 
or more warmth from the body of the incumbent than the 
other. * This principle would scarcely apply to the eggs of 
the Blue Bird, for they are nearly of the same size ; if there 
be any difference, it would be in favour of the eggs of the 
builder of the nest. How do the eggs get out of the nest ? 
Is it by the size and nestling of the young Cow Bird ? This 
cannot always be the case ; because, in the instance of the 
* The ingenious writer seems not to be aware, that almost all birds are 
in the habit, while sitting, of changing the eggs from the centre to the 
circumference, and vice versa , that all of them may receive an equal share of 
warmth. 
