, THE DISTRIBUTION OF BRITISH ANIMALS.
THE report that some malicious person had liberated rattlesnakes in Ireland turned out to be untrue. But in the comments which followed attention was drawn to the great limitations in the distribution of British animals of many kinds in Ireland, as well as to some interesting examples of their very local habitats in Great Britain. The number of species of land mammals existing in historic times as com- pared with those on the Continent of Europe decreases the nearer the land approaches the main Atlantic. Thus while, according to the author of an interesting article in the Edin- burgh Review on the "Survival and Destruction of British Mammals," there are ninety mammals in Germany, and sixty even in Scandinavia, with its Arctic or sub-Arctic climate, there are only forty-seven in England and Scotland, while in Ireland the list is decreased by twenty-one species, which do not, and never did, exist there. Among the Scandinavian creatures not found in this country are the elk, the glutton, the lemming, and the reindeer, besides the wolf and the bear, which did survive into historic times in Great Britain. But the contrast between the stock of land mammals in England and Ireland, though divided north and south by a narrow interval, is so enormously greater than the disparity between the beasts of Scandinavia and Scotland, between which lies the whole breadth of the North Sea, that some explana- tion has to be sought in theory. The view generally adopted is that, though the North Sea is wide, it is very shallow, while the Irish Channel is very deep. When the British Isles rose out of the sea, it is believed that they were, or became, united to the Continent of Europe, and that the animals crossed from thence first into England and then into Ireland, but by a broad connection in the case of the former and by a narrow one in the case of the latter, where perhaps only a backbone of land joined Ireland to Wales or to Argyll- shire, with deep sea on either side. When the lands between England and the Continent on the east once more sank and became the North Sea, and the further wandering of European animals into England was stopped, and the separa- tion of Ireland from England also took place, it is held that only certain of the animals had succeeded in passing over into the western island, and that the absence of the others from the Irish fauna is thus explained.
It is at least as probable that the absence of some Is due to their inability to live there. The causes of animal health and disease, and of their survival or de- generation, are very obscure. But the inability of species to maintain themselves in what are apparently favour- able surroundings is as observable among domesticated animals as among those in a state of nature. Among the latter, though the English hare has been more than once established in Irish parks, it never seems to multiply ; and black game, once common in very many parts of the South of England, as well as in the North, do not exist in Ireland at all.. But it is highly probable that this is because the climate does not suit them. Various instances are quoted in which the birds have been turned out on large estates. But they have never become established, owing apparently to natural, causes. There seems to be evidence that the capercaillie formerly inhabited Ireland. Giraldus says that the Pavo sylrestria,by which he probably means capercaillie, was commoner in the twelfth century Than were red grouse. Willoughby in 1678 says of the capercaillie that "we are told that it is found in Ireland"; O'Flaherty, writing in 1684, mentions it; and it is noted in a statute of the eleventh year of Queen Anne "that the species of cocks of the wood peculiar to this kingdom [Ireland] is in danger of being lost." On the other hand, a country formerly well suited to the well-being of a species may undergo changes which lead to its disappear. ance, and then once more become habitable by it. Thus the capercaillie was formerly found in Denmark, as its remains in the "kitchen middens " show, the country being probably at that time covered with forest. The forests there, as in Scotland, disappeared, and with them the oapercaillie. The latter have been restored to Scotland, and are now steadily increasing. But the success of the experiment was due to the fact that the reintroduction of the bird coincided in time with the reafforestation of Scotland.
Though there are no snakes in Ireland, it does not follow that they never got there, supposing the hypothesis of the narrow bridge to be correct. It is equally open to conjecture that if they did, they found the climate uncon- genial, and that, supposing the rattlesnakes had not been merely creatures of imagination, they would not have sur- vived. Several attempts are known to have been made to introduce snakes. In one the specimens turned out were most carefully, and one would imagine very properly, killed by the country people, an action of which an eminent naturalist quaintly remarked that "the failure of the attempts to intro- duce snakes into Ireland is not to be attributed to anything connected with the climate or other local circumstances, but rather to the prejudices of the inhabitants which lead to their destruction." A Mr. Davis informed the author of "The Natural History of Ireland" that the ringed snake "has several times been introduced, but seldom, if ever, survives the first winter. Some hundreds are said to have been liberated on a demesne near this a few years ago, but not one was to be met with twelve years later."
It is not correct to say that there are no frogs or toads in Ireland, though it is very remarkable that the common toad is not found there. The natterjack toad is a native of Kerry, though it does not appear to be found elsewhere. It is an example of the mania which some people have for meddling with Nature that a Dr. Guithers in 1699 took the trouble to procure frogs' spawn from England, since which time they have multiplied in Ireland. But the common lizard is found in many parts of the island. The slowworm is not. Though the common toad, and till recent times the frog, was not found in Ireland, it is worth remembering that the English reptiles and batrachians are very local in their dis- tribution. The natterjack toad is only found in certain counties. The edible frog was formerly only found in Foul mire Fen, in Cambridgeshire, and the sand lizard is most capricious in the choice of a home. The "beautiful green lacertx" which Gilbert White saw on the sunny banks near Farnham are to be found there still, the males being of the green colour ; and also near Bournemouth, and in Dorsetshire beyond Poole Harbour. Yet there are many suitable places where none are seen, and then they reappear again on some sand-hills on the coast of Lancashire, near Southport.
• On the other hand, the absence of many species in Ireland which are, or were, commonly found in the larger island can only be explained on the supposition that they never reached the country. Among these are the wild-cat, the polecat, and the weasel. Yet the marten was always plentiful on the other side of St. George's Channel ; and stoats abound in the West. Five of the fourteen species of bat found in England have not been taken in Ireland, neither is the common shrew found there, or the water-shrew, or the mole, though the last is found in Anglesey.
Only six of the fifteen British rodents are found in Ireland, and of these, one, the squirrel, was probably introduced. Neither is the roe-deer indigenous. In sup- port of the general theory that the immigration of the English fauna was difficult in the earlier periods, and sub- sequently checked altogether, may be cited the analogous instance of the Isle of Man. There, as in Ireland, there are no moles, no snakes, and no toads. On the other hand, both
the sand lizard and the common lizard are found there. The badger is not a native, nor at present is the fox. But the Manx foxes are said to have been killed off.
That many of our butterflies are narrowly local is due, generally speaking, to the fact that the plant on which the larva) feed is local also, such, for instance, as the wild pea on which the larva of the Lulworth skipper feeds. The capriciousness of the distribution of some of the British birds, especially of the choice made by the returning migrants for their summer quarters, cannot be so easily explained. Thus the- black-and-white flycatcher chooses always to journey on north of the Trent, though its food supply would be equally assured if it stayed in the Southern Counties. The nightingale prefers not to pass north of the Trent, possibly for climatic reasons. But these cannot be its motives for refusing to go into Devonshire. Three of our animals, the red grouse, the "blue" hare, and the ptarmigan, are sometimes spoken of as Arctic species. It would perhaps he more correct to describe the two latter as" Alpine," though the red grouse is admitted to be only an island form of the Arctic 1-per or willow grouse. But the "blue" hare and ptar- migan, though found on the mountains in the Arctic Circle, seem as a rule to conform their habitat rather to climates dependent on altitude for their conditions than to those which are "Arctic." They are found on the Alps and the Pyrenees; while the ptarmigan extends its range to most of the elevated mountain peaks of the Old World. Yet in Great Britain the mountain, or "blue," hare never crosses the Border, while the grouse comes a hundred miles further south. It seems inexplicable that the " blue " hare should not pass along the Border heights, and so down the Pennines, when in Ireland it is found much further south, and on lower ground.
Previous page
