430 
Brewer’s Remarks on 
His first position is undoubtedly sound ; as in every 
instance, where two cow-buntings have been known to 
have been hatched in the same nest, it has uniformly 
resulted in the death of the smaller birds. 
The second position cannot be so readily admitted. 
That it does frequently occur is undisputed, but that the 
reverse is much more frequently the case is equally unde- 
niable. The very fact that the circumstance was unknown 
to men of such observation as Wilson, Audubon and Nut- 
tall, should make us hesitate, before, from a few occasional 
instances, we set it down at once, as a general rule. 
The third rule Mr. Ord founds upon the circumstance 
before alluded to, of his twice finding the egg of a troopial 
in the nest of the wood-thrush. Upon these slight grounds 
he does not hesitate to set it down as a general rule, that 
larger birds invariably hatch these eggs when entrusted 
to their care. If new rules are to be admitted as well- 
founded, and old ones to be dismissed as unfounded, upon 
such slight grounds and groundless inferences as Mr. Ord 
would have them, the laws of nature, unchanging and 
immutable as they in reality are, will be made to appear 
as uncertain as the sands of the sea-shore. If he had 
merely assumed that this fact held true with the wood- 
thrush, nothing could have been said ; but what right has 
he to assume that the same is the case with every other 
bird, larger than the cow black-bird ? it is well known 
that the cat-bird invariably removes the eggs of strange 
birds not merely of different, but even of the same spe- 
cies, and the robin as invariably forsakes her nest if thus 
intruded upon. And until Mr. Ord can adduce satisfac- 
tory proof that the troopial is hatched and nursed in the 
nest of the meadow lark, the Baltimore oriole, the red- 
winged black-bird, the king-bird, the ferruginous thrush, 
the Cow Black-Bird. 
431 
the cat-bird, the robin, the hermit thrush, the ground 
robin, the cardinal grosbeak, the cuckoo, the woodpecker, 
&tc., (I ask not all — a few species will suffice), he cannot 
but be thought to have hastily adopted an unfounded and 
untenable position. 
His last position, that the cow-bunting will drop her 
egg in a nest which contains more than one egg, is a fact 
of too common occurrence to need confirmation. One 
would think it a fact too well known to the veriest tyro 
in ornithology to require being mentioned at all ; least of 
all, of being brought forward as a new discovery. 
There is one circumstance, connected with the history 
of this bird, which does not appear to be generally known. 
It has been mentioned that when a cow black-bird’s egg 
is deposited in a nest newly finished, and before the owner 
has begun to lay, the bird will frequently enclose the egg 
in fresh materials so as to prevent it from ever hatching. 
It does not appear to be known that the bird will some- 
times, in order to get rid of the intruder, bury with the 
cow-troopial’s, her own eggs. That such is sometimes 
the case, the following will show. In the summer of 
1835, I found in the botanical garden in Cambridge, a 
nest of the summer yellow-bird, which a brood had evi- 
dently but just left. Its peculiarly elongated shape, at- 
tracted my notice. Upon examining it, I found that the 
bird had apparently first constructed a nest of the usual 
shape, and had deposited in it three of her own eggs. 
At this period, a cow black-bird had added another. Not 
wishing, as it would seem, to waste her time by rearing a 
stranger, to the probable destruction of her own offspring, 
and yet unwilling to be at the trouble of constructing a 
nest entirely anew, she merely built an additional story 
to it : thus effectually destroying the egg of the intruder, 
