Surely our cow-bird has missed this secret haunt on her rounds. Be not deceived! Within a half-hour after this egg was laid the sparrow and its mate, returning from a brief absence to view their prize, discover two eggs where they had been responsible for but one. The prowling foe had already discovered their secret; for she, too, is "an attendant on the spring," and had been simply biding her time. The parent birds once out of sight, she had stolen slyly upon the nest, and after a very brief interval as slyly retreated, leaving her questionable compliments, presumably with a self-satisfied chuckle. The intruded egg is so like its fellow as to be hardly distinguishable except in its slightly larger size. It is doubtful whether the sparrow, in particular, owing to this similarity, ever realizes the deception. Indeed, the event is possibly considered a cause for self-congratulation rather than otherwise—at least, until her eyes are opened by the fateful dénouement of a few weeks later. And thus the American cow-bird outcuckoos the cuckoo as an "attendant on the spring," taking her pick among the nurseries of featherdom, now victimizing the oriole by a brief sojourn in the swinging hammock in the elm, here stopping a moment to leave her charge to the care of an indigo-bird, to-morrow creeping through the grass to the secreted nest of the Maryland yellow-throat, or Wilson's thrush, or chewink. And, unaccountable as it would appear, here we find the same deadly token safely lodged in the dainty cobweb nest of the vireo, a fragile pendent fabric hung in the fork of a slender branch which in itself would barely appear sufficiently strong to sustain the weight of a cow-bird without emptying the nest.
Indeed, the presence of this intruded egg, like that of the European cuckoo in similar fragile nests, has given rise to the popular belief that the bird must resort to exceptional means in these instances. Sir William Jardine, for instance, in an editorial foot-note in one of Gilbert White's pages, remarks:
"It is a curious fact, and one, I believe, not hitherto noticed by naturalists, that the cuckoo deposits its egg in the nests of the titlark, robin, and wagtail by means of its foot. If the bird sat on the nest while the egg was laid, the weight of its body would crush the nest and cause it to be forsaken, and thus one of the ends of Providence would be defeated. I have found the eggs of the cuckoo in the nest of a white-throat, built in so small a hole in a garden wall that it was absolutely impossible for the cuckoo to have got into it."
In the absence of substantiation, this, at best, presumptive evidence is discounted by the well-attested fact that the cuckoo has frequently been shot in the act of carrying a cuckoo's egg in its mouth, and there is on record an authentic account of a cuckoo which was observed through a telescope to lay her egg on a bank, and then take it in her bill and deposit it in the nest of a wagtail.
There is no evidence to warrant a similar resource in our cow-bird, though the inference would often appear irresistible, did we not know that Wilson actually saw the cow-bird in the act of laying in the diminutive nest of a red-eyed vireo, and also in that of the bluebird.
And what is the almost certain doom of the bird-home thus contaminated by the cow-bird?
A Greedy Foster-child
The egg is always laid betimes, and is usually the first to hatch, the period of incubation being a day or two less than that of the eggs of the foster-parent. And woe be to the fledglings whom fate has associated with a young cow-bird! He is the "early bird that gets the worm." His is the clamoring red mouth which takes the provender of the entire family. It is all "grist into his mill," and everything he eats seems to go to appetite—his bedfellows, if not thus starved to death, being at length crushed by his comparatively ponderous bulk, or ejected from the nest to die. It is a pretty well established fact that the cuckoo of Europe deliberately ousts its companion fledglings—a fact first noted by the famous Dr. Jenner. And Darwin has even asserted that the process of anatomical evolution has especially equipped the young cuckoo for such an accomplishment—a practice in which some accommodating philosophic minds detect the act of "divine beneficence," in that "the young cuckoo is thus insured sufficient food, and that its foster-brothers thus perish before they have acquired much feeling."
The following account, written by an eye-witness, bears the stamp of authenticity, and is furthermore re-enforced by a careful and most graphic drawing made on the spot, which I here reproduce, and fully substantiates the previous statement by Dr. Jenner. The scene of the tragedy was the nest of a pipit, or titlark, on the ground beneath a heather-bush. When first discovered it contained two pipit's eggs and the egg of a cuckoo.
"At the next visit, after an interval of forty-eight hours," writes Mrs. Blackburn, "we found the young cuckoo alone in the nest, and both the young pipits lying down the bank, about ten inches from the margin of the nest, but quite lively after being warmed in the hand. They were replaced in the nest beside the cuckoo, which struggled about till it got its back under one of them, when it climbed backward directly up the open side of the nest and pitched the pipit from its back on to the edge. It then stood quite upright on its legs, which were straddled wide apart, with the claws firmly fixed half-way down the inside of the nest, and, stretching its wings apart and backward, it elbowed the pipit fairly over the margin so far that its struggles took it down the bank instead of back into the nest. After this the cuckoo stood a minute or two feeling back with its wings, as if to make sure that the pipit was fairly overboard, and then subsided into the bottom of the nest.
"I replaced the ejected one and went home. On returning the next day, both nestlings were found dead and cold out of the nest.... But what struck me most was this: the cuckoo was perfectly naked, without a vestige of a feather, or even a hint of future feathers; its eyes were not yet opened, and its neck seemed too weak to support the weight of the head. The pipit had well-developed quills on the wings and back, and had bright eyes, partially open, yet they seemed quite helpless under the manipulations of the cuckoo, which looked a much less developed creature. The cuckoo's legs, however, seemed very muscular; and it appeared to feel about with its wings, which were absolutely featherless, as with hands, the spurious wing (unusually large in proportion) looking like a spread-out thumb."
Considering how rarely we see the cow-bird in our walks, her merciless ubiquity is astonishing. It occasionally happens that almost every nest I meet in a day's walk will show the ominous speckled egg. In a single stroll in the country I have removed eight of these foreboding tokens of misery. Only last summer I discovered the nest of a wood-sparrow in a hazel-bush, my attention being attracted thither by the parent bird bearing food in her beak. I found the nest occupied, appropriated, monopolized, by a cow-bird fledgling—a great, fat, clamoring lubber, completely filling the cavity of the nest, the one diminutive, puny remnant of the sparrow's offspring being jammed against the side of the nest, and a skeleton of a previous victim hanging among the branches below, with doubtless others lost in the grass somewhere in the near neighborhood, where they had been removed by the bereaved mother. The ravenous young parasite, though not half grown, was yet bigger by nearly double than the foster-mother. What a monster this! The "Black Douglass" of the bird home; a blot on Nature's page!