Page:Rothschild Extinct Birds.djvu/12

 viii these old writers only mentioned such species which impressed themselves on their memories either from their size, peculiar shape, beauty of plumage, or excellence and usefulness for food—in fact the culinary property of the various birds seems to have been their principal interest. One of the most interesting phenomena connected with recently extinct birds is the resemblance of the fauna of the Mascarene Islands and that of the Chatham Islands in the possession of a number of large flightless Rails, though the significance of this fact has been much exaggerated.

On the whole, this book is confined to species actually known to be extinct, but a few are included of which a small number is still known to exist, because firstly there seems no doubt that they will vanish soon, and secondly, as in the case of Notornis, it was necessary to clear up certain misconceptions and contradictory statements. In the case of a few species believed to be quite extinct, it is possible that some individuals may still exist in little known parts of their range, while on the other hand it is more than likely that several of the species referred to in my lecture (Proc. Orn. Congress pp. 191-207, 1907) as threatened with destruction, have already ceased to live. This may also be the case with some birds not alluded to at all.

In several instances I have treated of extinct flightless species under genera including existing species capable of flight. This may appear to be inconsistent, seeing that I maintain Notornis separate from Porphyrio, but, while not considering flightlessness in itself a generic character, the great development of the wing-coverts and the modification of the toes appear of sufficient generic value in this case. I know that several of the most eminent ornithologists of the day, among them Dr. Sharpe, differ from me, and are convinced that the loss of the power of flight is so profound a modification, that it is imperative that we should treat it as sufficient for generic distinction.

While agreeing that many genera are founded on much less striking modifications, I cannot concur in this opinion, for, unless the loss of the power of flight is also accompanied by other changes, in some cases it is difficult to find at first sight even specific differences other than the aborted wings.

The cause of recent extinction among birds is in most cases due directly or indirectly to man, but we also have instances of birds becoming extinct for no apparent reason whatever.

Man has destroyed, and is continually destroying species directly, either for