This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913 edition. Excerpt: ...are in process of transformation into nidicolous types--such as, for example, the gannets, cormorants, pelicans and their allies, which in the early stages of development are now absolutely helpless, and some are losing their downy covering as in typical nidicolous birds. While the pelicans always nest ...
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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913 edition. Excerpt: ...are in process of transformation into nidicolous types--such as, for example, the gannets, cormorants, pelicans and their allies, which in the early stages of development are now absolutely helpless, and some are losing their downy covering as in typical nidicolous birds. While the pelicans always nest upon the ground, some species both of gannets and cormorants nest in trees, either sporadically or constantly, as the conditions of the environment may determine. Various intermediate stages in this process of " hobbling " may be studied in the case of those species which, having precocious young, nest in colonies, often of vast size, or on the ledges of precipitous cliffs. The reduction of the food-yolk, and the consequent earlier hatching of the young of such species, are decidedly advantageous changes. The gain of such curtailment of movement is, to species which nest in colonies on the ground, obvious. Active young, hatched in colonies affording free space wherein to roam, would soon become lost amid the general crowd of nestlings, and hence speedily starve--even if the adults had acquired the habit of indiscriminately feeding any nestling of the colony which clamoured for food. In the case of cliff-breeding species like guillemots and razor-bills, and many species of gulls, this quiescence saves an enormous mortality through falls from the cliffs. Whilst a large number of birds have adopted this expedient of curtailing the activity of the young, thereby increasing the burden of parental responsibility, there are certain species of gallinaceous birds known as the moundbuilders or megapodes, which have succeeded in reducing the ties of offspring to the smallest possible limits--without descending to parasitism--by enormously...
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