into the plastering
business; but his skill is not so well developed as that of his
oriental cousin, whose mud cottage is a model of its kind.

[1] The writer referred to is Mr. H. C. Tracy, to whose charming
article in "The Wilson Bulletin," published at Oberlin, Ohio, I am
indebted for all my material on the rock nuthatch.

A FEATHERED PARASITE*

*Reprinted from Appleton's "Popular Science Monthly," with additions.

Nothing could more clearly prove that a common law runs through the
whole domain of Nature than the fact that in every division of her
realm there seems to be a class of parasites. In the vegetable world,
as is well known, there are various plants that depend wholly on other
plants for the supply of their vital forces. And in the human sphere
there are parasites in a very real and literal sense--men and women who
rely upon the toil and thrift of others to sustain them in worthless
idleness.

In view of the almost universal character of this law it would be
strange if these peculiar forms of dependence did not appear in the
avian community. We do find such developments in that department of
creation. Across the waters there is one bird that has won an
unenviable reputation as a parasite: the European cuckoo relies almost
wholly on the efforts of its more thrifty neighbors to hatch and rear
its young, and thereby perpetuate the species. Strangely enough, our
American cuckoos are not given to such slovenly habits, but build their
own nests and faithfully perform the duties of nidification, as all
respectable feathered folk should. However, this parasitical habit
breaks out, quite unexpectedly, it must be conceded, in another
American family of birds entirely distinct from the cuckoo group.

In America the cowbird, often called the cow bunting, is the only
member of the avian household that spirits its eggs into the nests of
other birds. The theory of evolution can do little toward accounting
for the anomaly, and even if it should venture upon some suggestions it
would still be just as difficult to explain the cause of the evolution
in this special group, while all other avian groups follow the law of
thrift and self-reliance.

[Illustration: Cowbird]

The cowbird belongs to the family of birds scientifically known as
_Icteridae_, which includes such familiar species as the bobolinks,
orioles, meadowlarks, and the various kinds of blackbirds, none of
which, I am glad to say, are p