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310
THE GEOGRAPHICAL DISTRIBUTION OF ANIMALS.

one who will consult Lane's "Arabian Nights," vol. iii., chap. 25, note 32, and Wallace's account of the great bird of paradise, in his "Malay Archipelago," chap. 38, will, I think, be convinced, like myself, of the identity of the Aru Islands with the islands of Wák-wák of the Arabian writers.[1] But even when animals are spoken of under their proper names, it will often be no easy matter to identify them in a translation; for I have generally found that the English, French, and German equivalents for the vernacular names of common animals or plants are rarely to be ascertained with any accuracy from the best existing dictionaries; and this difficulty would be greatly increased in the case of Oriental or ancient writings, in which animals, perhaps now extinct, would frequently be described in very hyperbolical language.

To return from this digression to Europe, we need not wonder that its present fauna is so much poorer than in post-glacial times, or even than a few centuries ago. The advance of cultivation, the felling of forests, and the draining of marshes have exterminated many species, even in our own day, while others have been destroyed as noxious creatures, as the wolf in Britain, and the lion in Germany[2] and Greece. Others were exterminated for food, as the great auk in the northern regions; and the urus and aurochs, both now almost extinct, the former only existing as (Bos scoticus) and the other in Lithuania and the Caucasus, the last being the only locality where it is still actually wild. As, however, these wild cattle are fierce and dangerous animals, they may have been exterminated partly for this reason. A very interesting volume could be written on the animals which have disappeared from Europe within historic times. When the ancient world was overrun by huge and destructive animals, it must have been difficult for men to make any progress in civilization; but when the glacial epoch had swept all before it, it was much easier for men to improve their condition. So far as we know, the ancient centres of civilization, such as central Asia and Egypt, were less overrun with wild beasts than others.

The islands of Corsica and Sardinia, though barely alluded to by Wallace, are interesting from the number of peculiar species which they already contain, and for the still larger number of local forms, which, if isolated for a sufficient time, will ultimately become perfectly distinct species. Their fauna appears to have been derived from the mainland of Italy at a period when that country was already fully stocked with its present fauna, as they possess a large proportion of the Italian species. They have apparently been separated from the mainland for a much longer period than Britain from France; for, although Guénée calls Britain "le pays des varietés," well-marked species have not yet had time to develop themselves. Here, however, other considerations step in. The much hotter and finer climate of Corsica and Sardinia may have stimulated the more rapid differentiation of species. And although we are still ignorant of many of the laws which govern the range of species, yet it appears from the large proportion of species common on the French coast, and not extending to Britain, that Britain was separated from France before France had fully acquired its present fauna and flora. The same reasoning will apply to Ireland, which is much poorer in species than Britain.

Some writers think that the glacial period has not wholly passed away, and that the earth has not yet recovered its normal temperature; and although it would require a long series of observations, extending over many years, if not centuries, to arrive at absolute certainty, yet there are some historical grounds for believing that the climate of all Europe was much more severe only two thousand years ago than at present.[3] How far the clearing of forests, etc., may have influenced the climate we do not yet know, nor whether its gradual improvement is due to local or general causes. It is quite possible that the animals and plants now confined to eastern, southern, or central Europe are still extending their range north and west, so far as they meet with no barriers to their further migrations.

In the case of the British Islands, there are other conditions besides breaks of geographical continuity which hinder the spread of some species. The unfavorable climate of the northern and western portions is probably one cause of the restricted range of many species, and their total absence from Scotland, Ireland, and, in many cases, even from the north or west of England. Nothing strikes a

  1. I am not aware that the reputed occurrence of this bird in New Guinea has been confirmed; and the islands of Wák-wák are always spoken of in the plural.
  2. Which it is believed to have inhabited during the heroic age.
  3. Compare Mallet's "Northern Antiquities," pp. 242, 243.