Notice of Audubon's Birds of America. 135 
tious egg about two thirds buried, the upper edge only being 
visible, so that, in many instances, it is probable that this species 
escapes from the unpleasant position of becoming a nurse to the 
sable orphan of the cowbird. She, however, acts faithfully. the 
part of a foster-parent when the egg is laid after her own.’ 
“The following note from my friend Dr. 'T. M. Brewer, shows 
that this little bird is capable of still greater exploits, ‘There is 
a very interesting item in the history of the yellow-poll warbler, 
which has been noticed only within a few years, and which is 
well deserving of attention, both for the reasoning power which 
it exhibits, and for its uniqueness, for it is not known, I believe, 
to be practiced by any other bird. I allude to the surprising in- 
genuity with which they often contrive to escape the burthen of 
rearing the offspring of the cow troopial, by burying the egg of 
the intruder. Ihave known of four instances in which single 
eggs have been buried by the yellowbird, and building a second 
story to her nest and enclosing the intruder between them. In 
one instance, three of the Sylvia’s own eggs were thus covered 
along with that of the cow blackbird; and in another, after a 
blackbird’s egg had been thus concealed, a second was laid, 
which was similarly treated, thus giving rise to a three storied 
nest. This last you have in your possession, and will, 1 hope, 
vat to the nerd a putas * well * a people description of 
“ The rein alluded to mesic may be thus eatpeds. A nest 
of the usual form had been first constructed, of which the exter- 
nal diameter was three inches. It is composed of cotton rudely 
interwoven with flaxen fibres of plants, and lined with cotton of 
a reddish color, with some hairs round the inneredges. The egg 
of the cowbird having been deposited in this nest, another of a 
larger size, three inches and three quarters in external diameter, 
has been built upon it, being formed of the same materials, but 
with less of the flaxen fibres. The egg is thus surmounted bya 
layer three quarters of an inch thick, and was discovered by 
opening the lower nest from beneath. It is agglutinated to the 
lining of the nest, having been addled and probably burst. In ~ 
this second nest a cowbird had deposited an egg, which was, in 
like manner, covered over by a third nest, composed of the same 
materials, and of warcaele the same size as the second.” - 
