is parasite of the bird home _be_ a factor in the divine plan
of Nature's equilibrium, looking towards the survival of the fittest and
the regulation of the sparrow and small-bird population, which we must
admit, how am I to know but that this righteous impulse of the human
animal is not equally a divine, as it is certainly a natural institution
looking to the limitations of the cow-bird? One June morning, a year or
two ago, I heard a loud squeaking, as of a young bird in the grass near
my door, and, on approaching, discovered the spectacle of a cow-bird,
almost full-fledged, being fed by its foster-mother, a chippy not more
than half its size, and which was obliged to stand on tiptoe to cram the
gullet of the parasite.

The victims of the cow-bird are usually, as in this instance, birds of
much smaller size, the fly-catchers, the sparrows, warblers, and vireos,
though she occasionally imposes on larger species, such as the orioles
and the thrushes. The following are among its most frequent dupes,
given somewhat in the order of the bird's apparent choice: song-sparrow,
field-sparrow, yellow warbler, chipping-sparrow, other sparrows,
Maryland yellow-throat, yellow-breasted chat, vireos, worm-eating
warbler, indigo-bird, least-flycatcher, bluebird, Acadian flycatcher,
Canada flycatcher, oven-bird, king-bird, cat-bird, phoebe, Wilson's
thrush, chewink, and wood-thrush.

But one egg is usually deposited in a single nest; the presence of two
eggs probably indicates, as in the case of the European cuckoo, the
visits of two cow-birds rather than a second visit from the same
individual--the presence of two cow-bird chicks of equal size being
rather a proof of this than otherwise, in that kind Nature would seem to
have accommodated the bird with an exceptional physiological resource,
which matures its eggs at intervals of three or more days, as against
the daily oviposition of its dupes, thus giving it plenty of time to
make its search and take its pick among the bird-homes. Whether the
process of evolution has similarly equipped our cow-bird I am not aware;
but the vicious habits of the two birds are so identical that the same
accommodating functional conditions might reasonably be expected. It is,
indeed, an interesting fact well known to ornithologists that our own
American cuckoos, both the yellow-billed and black-billed, although
rudimentary nest-builders, still retain the same exceptional interval in
their egg-laying as d