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Show 18/0.] MR. HUDSON ON THE BIRDS OF BUENOS AYRES. 549 certainly would have given it a distinguished place in the •* Origin of Species ;' and he could not have found any more remarkable case for illustrating the ' mistakes and imperfections to which instinct is liable,' and which he considers favourable to his theory. " There are few small birds here into whose nests the female Blackbird does not intrude; and great is the domestic confusion introduced by her visits. She does not choose nests for their size or for their architects being hard or soft-billed birds, but lays her eggs indiscriminately wherever she can. I have never found her eggs in the nest of the Churinche (Pyrocephalus rubineus), probably because that pugnacious little bird remains by it and is able to beat her off. I have also observed that the Blackbird never lays in domed nests, though parties of them are constantly seen about the ovens of the Oven-bird (Furnarius), climbing over, peering into, and even entering and examining them very curiously. It would be difficult to enumerate all the little birds who are compelled to rear the young Blackbirds ; but their favourite nests, probably because easiest discovered, and undefended against their intrusion, are those of the Cachila (Anthus correndera), the Chingolo (Zonotrichia pileata), the Jilquero (Chrysomitris barbata), the Tijereta (Milvulus violentus), and the Yellowbreast (Pseudoleistes virescens). " The nests of the last two are particularly preferred; indeed I seldom find a nest of either of them but it contains more eggs of the Blackbird than of the rightful owners, while from one or two to hah a dozen female Blackbirds are usually to be observed near it. " They frequently begin depositing their eggs before the nest is finished, upon which it is generally abandoned; and often so-many eggs are laid in a nest, that, even if they are set on, few or none of them can be batched. The nest of the Tijereta is usually found with from five or six to a dozen Blackbird's eggs in it, that of the Yellow-breast, which is deeper, with from fifteen to twenty; but what the nest contains are seldom all the eggs that have been laid in it; for, by looking on the ground under tbe tree or bush, many more will frequently be discovered, thrown down by the female Blackbird. Another destructive habit of this bird (destructive to its own increase as well as to that of other species) is its habit of pecking holes in the eggs it finds in the nest where it lays. This is not a fixed, invariable habit, but irregular, as are its reproducing-instincts. Sometimes the shells are so broken that the yelk is spilt in the nest; at other times they peck small holes in the shells; and sometimes they strike their bill into one egg and fly away with it. as a Pigeon does with the shell of an egg it bas just hatched. This I have seen them do; and I have often found an egg with a hole in it several feet from the nest, doubtless removed in this way. Some nests are found containing a dozen or twenty eggs, every one with holes pecked in them. In the laying-season each female is generally attended by one or two, and sometimes three males, who quietly remain near while she is on the nest. The Blackbird also dropsits eggs on the ground; and I continually find these lost eggs on ploughed fields, roads, and spots of barren earth. |