the parent
bird. She may often be seen searching anxiously through the trees or
bushes for a suitable nest, yet she may still oftener be seen perched
upon some good point of observation watching the birds as they come and
go about her. There is no doubt that, in many cases, the cowbird makes
room for her own illegitimate egg in the nest by removing one of the
bird's own. I found a sparrow's nest with two sparrow's eggs and one
cowbird's egg, and another egg lying a foot or so below it on the
ground. I replaced the ejected egg, and the next day found it again
removed, and another cowbird's egg in its place. I put it back the
second time, when it was again ejected, or destroyed, for I failed to
find it anywhere. Very alert and sensitive birds, like the warblers,
often bury the strange egg beneath a second nest built on top of the
old. A lady living in the suburbs of an Eastern city heard cries of
distress one morning from a pair of house wrens that had a nest in a
honeysuckle on her front porch. On looking out of the window, she beheld
this little comedy,--comedy from her point of view, but no doubt grim
tragedy from the point of view of the wrens: a cowbird with a wren's egg
in its beak running rapidly along the walk, with the outraged wrens
forming a procession behind it, screaming, scolding, and gesticulating
as only these voluble little birds can. The cowbird had probably been
surprised in the act of violating the nest, and the wrens were giving
her a piece of their minds.

Every cowbird is reared at the expense of two or more song-birds. For
every one of these dusky little pedestrians there amid the grazing
cattle there are two or more sparrows, or vireos, or warblers, the less.
It is a big price to pay,--two larks for a bunting,--two sovereigns for
a shilling; but Nature does not hesitate occasionally to contradict
herself in just this way. The young of the cowbird is disproportionately
large and aggressive, one might say hoggish. When disturbed, it will
clasp the nest and scream and snap its beak threateningly. One was
hatched out in a song sparrow's nest which was under my observation, and
would soon have overridden and overborne the young sparrow which came
out of the shell a few hours later, had I not interfered from time to
time and lent the young sparrow a helping hand. Every day I would visit
the nest and take the sparrow out from under the potbellied interloper,
and place it on top, so that presently it was