THE NATURALIST.

Otago Witness, Issue 2106, 5 July 1894, Page 48

THE NATURALIST.

Evolved Woodpeckers.

The following passage from a notice in the Critical Review of Dr J. H. Hirling's " Darwinianism" is an object-lesson in "natural selection " : —

"Of two birds that feed on insects, conceive the one of them to have varied favourably in the beak — to be possessed, that is, of the stronger beak; it will have the advantage over the other, and it will transmit this advantage to its descendants. In these this advantage can only grow ; for they will always possess, and, as is evident, always increasingly possess, the strongest beaks. That strength of beak will give the advantage is but a corollary on the habits of the birds themselves. They haunt fallen trees — namely, those under the bark of which the insects burrow.fcto'fall a prey preferably to the strongest beak that can dig for them. Still even the strongest beak does not always succeed ; its tongue, conceivably, is too short, and the insects occasionally escape it. Let a strong-beaked bird be born with a longer

tongue than the rest, why, it, too, will have the advantage over its fellows, and it will also transmit this advantage to the descendants of itself. Strong-beaked, long-tongued insectfeeders will nowevidently constitute the rule, but unfortunately in course of time there occurs a dearth of fallen timber ; strength of besk and length of tongue scarcely suffice any longer for more than the scantiest and miserablest of existences. Bat see, one of them gets born with sharper fore-claws than any one of its brothers! it is actually seen to ascend standing trees, and, triumphantly tapping the bark, luxuriously to feed on an all-abundant treasure and store of hitherto unreachable and unreached insects. Once again there can be only one result — the birds that have blunt fore-claws will gradually die off, and the sharp fore- claws will alone remain. But even these come to be at a disadvantage in the straggle for life. An individual is born that adds on to the already existent fore-claw — actually I — a sharp hindclaw. Consummatum est ! the sharp foreclaws must perish, for their time has come. But even the triumphant hind-clawers have to suffer defeat in their turn. There is born among them one who can stick his tail, as well as his claws, into the tree, up which he can run with an all-conqnering swiftness. He and his children simply starve out all the rest, and are left alone at the last in the undisturbed possession of every rotten tree in the forest. On every one of them now there thrones an autocrat — a Pious Superbus! This, the wood-pecker, is a bird that, for the complicated adaptations it exhibits, is absolutely unparalleled. The bill is wedgeshaped and keen ; the tongue is long, nimble, sharp, barbed or beset with bristles bent backwards, and coated viscid ; the claws are strong and spiked to grasp even a perpendicular surface, and in this they are supported by the tail, the stiff -pointed-end feathers of which can keenly grasp also. The life of this bird being the running up and down old trees to pick holes into them in pursuit of insects, which it hunts and captures with its supple, long, gluey tongue, it is to be regarded in itself as glaringly and conspicuously a proof of the fact of natural selection ; for though possibly quite an ordinary bird at first, it has conspicuously, grown into what it is — a new species — by propagated successive advantages simply in pursuit of its own business 1"