the
spring; the flight from winter cold occurs in the spring instead of in
the autumn, and is toward the north instead of toward the south. Thus,
in February and March the Argentine cowbirds are seen flying in vast
battalions in the direction of the equatorial regions--that is,
northward--in whose salubrious clime they spend the winter. As our
northern autumn draws near and the southern spring approaches these
winged migrants take the air line for their breeding haunts in the
Argentine Republic and Patagonia. At the same time the migrants of the
northern hemisphere are pressing southward before the blustering north
wind. It all seems wonderful and solemn, this world-wide processional
of the seasons and the birds.

Naturally one would expect to find some other eccentricities in this
aberrant family besides that of parasitism, and in this expectation one
is not disappointed. There are two other species of cowbirds in the
Argentine country--the screaming cowbird (_Molothrus rufoaxillaris_)
and the bay-winged cowbird (_Molothrus badius_). The latter is only
partly a trencher on the rights of other birds--only half a parasite.
Indeed, it sometimes builds its own nest, which is quite a respectable
affair; but, as if to prove that it still has some remnants of cowbird
depravity in its nature, it frequently drives other birds from their
rightful possessions, appropriates the quarters thus acquired, lays its
eggs into them, and proceeds to the performance of its domestic duties
like its respectable neighbors. Its virtue is that it never imposes
the work of incubation and brood rearing on any of its feathered
associates, even though it does sometimes eject them from their
premises.

But what is to be said of the screaming cowbird? Instead of inflicting
its eggs on its more distant avian relatives, it watches its chance and
slyly drops them into the domicile of its bay-winged cousins, and
actually makes them hatch and rear its offspring! This seems to be
carrying imposture to the extreme of refinement, or possibly developing
it into a fine art, and reminds one of those human good-for-naughts who
"sponge" off their relatives rather than go among strangers.

Before closing this chapter I must call attention to one of the most
surprising discoveries ever made by an American observer of bird ways.
It was reported some time after my article on the cowbird was first
published in Appleton's "Popular Science Monthly." The obs