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We have discovered a most interesting curiosity for our natural-history cabinet the embodiment of a presumably new form of intelligence in the divine plan looking to the survival of the fittest. It is not known how many years or centuries it has taken the little warbler to develop this clever resource to outwit the cow-bird.
The argument has been stated very binefly: but little would be gained by the mere multiplication of instances, since, however many, they would bo selected instances from a single district, it is true, while those in the Descent of Man were brought together from an immeasurably wider field; but the principle is the same in both cases, and to what I have written it may be objected that, if, instead of twenty-five, I had given a hundred cases, taking them as they came, they might have shown a larger proportion of instances like that of the cow-bird, in which the male has a set performance practised only during the love-season and in the presence of the female.
From whichever side the wind blew it was calm here, and during the heaviest rain the birds would sit here in their thousands, pouring out a continuous torrent of song, which resembled the noise produced by thousands of starlings at roosting-time, but was louder and differed somewhat in character owing to the peculiar song of the cow-bird, which begins with hollow guttural sounds, followed by a burst of loud clear ringing notes.
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.
I remarked a long-tailed jay called Gobiyan or Fat , russet-hued ringdoves, the modest honey-bird, corn quails, canary-coloured finches, sparrows gay as those of Surinam, humming-birds with a plume of metallic lustre, and especially a white-eyed kind of maina, called by the Somal, Shimbir Load or the cow-bird.
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 cow-bird 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.
I recently read of a specimen containing four stories, upon the top of which downy pile the little warbler sat like Patience on a monument, presumably smiling at the discomfiture of the outwitted cow-bird parasite, who had thus exhausted her powers of mischief for the season, and doubtless convinced herself of the folly of "putting all her eggs in one basket."
The believer in the theory would put all these cases lightly aside, to cite that of the male cow-bird practising antics before the female and drawing a wide circle of melody round her; or that of the jet-black, automaton-like, dancing tyrant-bird; and concerning this species he would probably say that the plain-plumaged female went about unseen, critically watching the dancing of different males, to discover the most excellent performer according to the traditional standard.
The red-eyed vireo, on the other hand, though having apparently an easier task than the latter, in the lesser depth of her pensile nest, commonly abandons it altogether to the unwelcome speckled ovum always, I believe, if the cow-bird has anticipated her own first egg.
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