Some Curious Facts in the Distribution of the British Newts
Some curious facts in the geographical distribution of the three British species of tailed amphibians have recently been brought to light. Modern investigations have proved that the well-known statements in regard to this subject which have been copied and re-copied in almost all the English works of Natural History, to the effect that the Greatcrested Newt (Molge cristata) and the Common Newt (M. vulgaris) are generally common, and that the little Palmate Newt (M. palmata) is very rare and has only been found “near Bridgwater, the Isle of Wight, and near Reading,” are not only misleading but quite incorrect.
The real facts, as recently elucidated, are these. The Palmate, so far from being rare, is very widely distributed. It is found from Cornwall to Sunderland and from Anglesea to the Isle of Wight. This conspicuous and handsome little species, with webbed hind feet, is the only species recorded from Cornwall, where it is very common. In Devon, too, the Palmate can be found in every pond and roadside runnel, while the Common Newt is absent, and the Greatcrested, until a short time ago, was thought to be absent likewise. Some few months since, I discovered the latter species in a pool in North Devon, but before that time no authentic Devonshire specimen existed in collections. In Somerset M. cristata appears frequently, but is local, while as far up as Gloucester, the Palmate begins to grow local as well. Turning to Wales, it is important to notice the same conditions prevailing as those in the S.W. Peninsula, viz., the occurrence of the Palmate form to the almost total exclusion of the other two. As to the rest of England and to Scotland, the Palmate Newt is generally common but local; it has been recorded from a large number of counties, and also from Anglesea, Bardsea Island, the Isle of Rum, and the Isle of Wight; there are no newt records either from Lundy or the Scilly Islands. Professor James Clark informs me that he has seen no newt alive on the Scilly Islands, but there is, in his possession, a specimen of the Palmate species, which was captured by a resident of St. Mary’s, near Porthellick Bay. On the other hand, Mr. T. A. Dorrien-Smith, who was good enough to make careful inquiries for me, was unable to find any evidence of the existence of newts on the islands. Ireland pos- sesses only one species and that, contrary to all expectation, proves to be M. vulgaris. Dr. R. F. Scharff has found it, in its typical form, in about twenty localities N., S., E., and W. Reported occurrences of two species have always been founded on the sexual differences in the Common Newt.
Fossil remains are very scanty; bones, which are referable to the Greatcrested species and were discovered in the Forest Bed, appear to constitute the sole record. With such conflicting evidence as this, it seems to be quite impossible to decide which species is, phylogenetically, the oldest. According to the evidence of palæontology Cristata is the oldest, according to distribution in Great Britain and its occurrence on several outlying islands we should be led to expect Palmata, then Dr. Scharff’s report from Ireland arrives and makes the problem a three-cornered one; for it is safe to assume that, during the time of the hypothetical connection of Ireland with England, M. vulgaris was the only species existing, as it was the only one to cross the boundary into Ireland. It should therefore be the oldest.
The more remarkable facts, in connection with the distribution of these little amphibians, are to follow. It is now agreed on all hands that M. palmata is exceedingly common in Devon and Cornwall, the Common Newt absent, and the Greatcrested almost unknown. But all the older naturalists in the two counties were agreed in recording Cristata and Vulgaris, but Palmata only rarely. Thus the late Mr. Brooking Rowe, in a letter to Mr. E. E. Lowe (a former curator of the Plymouth Museum), which was published in the “Victoria C. Hist. Devon,” says: “As to the Smooth Newt (M. vulgaris) I am surprised at what you say (that it did not occur in the county). It was, without question, the common species some years ago and found everywhere. I was the first to record T. palmatus, and found it in a pond not far from here (Plympton).” We are driven to believe, either that the older naturalists failed to distinguish the obvious differences in the two species, or else, the more probable hypothesis, that within late years M. palmata has increased to such an extent that it has almost completely ousted the other two.
No less a person than the late Professor Edward Forbes (who was a Manxman) stated that “T. palustris and T. punctatus were by no means uncommon in their different habitats everywhere” on the Isle of Man. But no newts now exist there. If the older naturalists, with Professor Forbes, wrongly identified these newts, the former may gain a little consolation from the fact that they have sinned in good company.
However, I am strongly inclined to believe that for some considerable time past, the Palmate has been increasing in numbers, and widening its range to the prejudice of the other species. Its small size enables it to live in very small ponds and ditches, it has the widest distribution, and is the only species which is found in mountain pools. It would, therefore, seem to be able to stand greater variations in climate and environment. It is exceedingly unlikely that Professor Forbes should have made so glaring an error. It is easier to suppose that, in a succession of unfavourable years, when, among other things, an unusually small rainfall occurred, the two Manx species, M. cristata and M. vulgaris, became extinct on the island. The Palmate would be the most capable of withstanding these conditions, and would increase and multiply in other parts of the country, where, previously, it had already gained a footing. A careful study of newts in their natural habitats, over a series of years, affords convincing proof of a considerable rise and fall in the number of individuals of each species, in different seasons, which is, as often as not, quite inexplicable; at all events in terms of weather and climate. I think it highly probable that, on account of a recent supervention of a powerful combination of unfavourable conditions — just when, during one of these fluxes, the numbers were at the minimum — the Common and Greatcrested Newts have become extinct in many places, where they were once common, the result being that the hardier Palmate, left master of the field, has shot ahead and won in the struggle for existence. This increase (and the subsequent migration and dispersal which has occurred) presents a most interesting and unexpected phenomenon.