Part 5

There are probably two litters of from two to eight young, born between May and September.

*Water Shrew* (Neomys fodiens, Schreber).

The Water Shrew is our largest species, the length of head and body combined varying from three to three and three-quarter inches, the body of bulkier build than that of the Common Shrew, and the tail longer than the body. Its upper parts are dark coloured--from slaty black to dark brown--and the light ashy grey or dirty white of the under parts appear pure white by contrast. The snout is shorter and broader than that of the Common Shrew; the small eyes are blue, and the ears, which are entirely concealed, bear a tuft of white hairs. The brown feet are broader and the digits are bordered with stiff hairs which make them more efficient as paddles; and the tapering flattened tail of the adult has a double fringe of strong silver-grey hairs along its underside, constituting a "keel" and making it more efficient as a rudder. The hind foot usually exceeds three-quarters of an inch. The fur is finer and thicker than in the other British Shrews; and the upper and lower colour areas are sharply separated one from the other. Its aquatic habits have in some districts caused it to be known as Otter-Shrew. The tail is brown above and lighter below. Variation to full black is frequent, and albinos have been recorded.

The teeth have coloured tips like those of the other Shrews, but the points of the incisors are more hooked than in the two species of Sorex; moreover, there are two teeth less, the dental formula standing thus:--i 3/1, c 1/1, p 2/1, m 3/3 = 30. It is these differences in the teeth that has led to the Water Shrew being placed in a separate genus.

In wandering quietly along the streamside we may perchance see the Water Shrew sunning itself on a mossy stone by the margin of the water, for it is active by day as well as by night. We may see it make a sudden plunge into the stream, and present a beautiful appearance under water, for the fur carries a good deal of air entangled in it which gives the submerged body a silvery appearance. It chases the whirligig beetles and water-gnats on the surface, or routs at the bottom for caddisworms and other larvæ. Its haunts may often be detected by the little heaps of caddis cases on the bank, which it has brought ashore and emptied of their living contents. It eats other aquatic animals, such as snails, worms, small crustaceans, frogs, and small fishes; is not averse from a little carrion, and has been caught in a trap that was baited with cheese. It utters a cricket-like chirp not unlike that of the other Shrews.

As he seldom goes more than a couple of yards from the bank, the quiet observer may take full stock of his proceedings, for the limited range of his vision does not permit him to see you. He appears to be very buoyant in the water, swimming with his head slightly above the surface and the body spread out. Though he may walk for a time along the bottom, he never gets his fur wet. At times he makes distinct leaps out of the water, apparently after a flying insect.

His home is a burrow in the bank, and far inside the female lines a chamber with moss and fine roots, or weaves a round nest of grass and leaves where in May or June she brings forth her litter of five to eight minute blind and naked young. These develop rapidly and when they are five or six weeks old they are independent. There is probably a second brood in September. Like the other Shrews the males are great fighters.

He is found sometimes at a considerable distance from the water, apparently seeking a change of diet, or migrating to a more abundant food supply. It does not hibernate, and may be seen in winter pursuing its prey beneath the ice. Its chief enemy is the Owl, whose cast-up pellets frequently contain the skulls of Shrews.

The Water Shrew is much more local in its occurrence than are the other Shrews. With this reservation it may be said to be widely distributed throughout England, Wales, and Scotland; and in Staffordshire and Cheshire has been found at elevations of a thousand feet. It is not found either in Ireland, the Isle of Man, the Outer Hebrides, the Orkneys or Shetlands. In the Fen country it is known as the Blind-mouse.

FLYING MAMMALS: BATS

*Bats* (Chiroptera).

With the exception of the great class of Birds, the Bats are the only surviving backboned animals that possess the organs of true flight. Apart from this specialisation for a life in the air the Bats are very similar in their organisation to the Insectivora, and long ago Huxley pointed out that they were exceedingly modified Insectivora; but this modification marks them off sharply from their nearest allies, and the authorities have agreed that it constitutes a reason for setting them apart in a special order--the Chiroptera or wing-handed animals.

So complete has been the adaptation to an aerial life, involving both pairs of limbs, that they are no longer fitted for progression on the earth. The fingers of the hand have been so drawn out that they are longer than the forearm, and the middle finger is at least equal in length to the head and body, whilst the thumb has been converted into a hook by means of which the Bat can hang from any rough surface. Over these exaggerated finger-bones a broad web of skin has been stretched, and connected not only to the sides of the body but also to the hind legs as far as the ankle, and then nearly or quite to the tip of the slender tail. The effect of this great modification, whilst it creates a pair of great wings, is to render the hind limbs unfitted for ordinary locomotion, for these are so twisted out of the position assumed in quadrupeds that the knees are turned backwards. This is the cause of the awkward, shuffling movements of a Bat on the ground which make it quickly rise into the air or at least to climb some vertical surface.

Looking at the skeleton of a Bat, we shall find the vertebral column short, the neck short-boned but broad, the spinal cord being of great thickness at this part though reduced to a mere thread at the hips. The ribs are usually flattened and connected to a strong breastbone, which has a prominent keel for the attachment of powerful muscles controlling the wings. The tail controls the web connecting the hind legs, which acts as a rudder in flight and as a net helping to capture and retain the larger insects upon which the Bat lives.

The permanent teeth--which are quite different from the milk-teeth--vary in the different species, but they always have distinct roots, and in the British species the upper surface always runs into points or cusps, suited for cracking the chitinous shells of beetles.

The Bat's brain is considered to be of a low order; yet its senses are very acute. Spallanzani, in the latter part of the 18th century made a number of experiments on Bats, depriving them of sight, smell, and hearing, and observing their behaviour under such conditions. He found that when released in a room across which he had stretched numerous threads to block their flight, they in every case avoided these, even when directly in their course. They appear to be helped in this matter by the sensitive whiskers around the muzzle, as well as by the delicate membranes constituting the wings and the outer ears. In the Horse-shoe Bats there is also a great development of the appendages to the nose, known as the nose-leaf, which act as delicate organs of special perception.

In most of the genera there is considerable development of the ear as compared with other mammals. The little lobe that guards the entrance to the ear in the human subject, and is known as the tragus, is much elongated in the Bats so that it becomes a conspicuous feature, and its variation affords one of the characters for identification of the species. Our two Horse-shoe Bats alone are without any prominent tragus.

It is considered that the Bat's powers of flight are superior even to those of the birds. This is especially evident if we watch the rapidity with which it can change its speed, suddenly stopping when in full flight, then making sudden swoops and turning somersaults in a way that would evoke the admiration of the stunt-loving airman. The females as a rule have larger wings and heavier bodies than the males.

Perhaps to the majority of people the Bat appears to be a creature without a voice. It does, however, utter a shrill squeak which is so highly pitched that many human ears are incapable of perceiving it. On the other hand, the Bat has similar deficiencies; and it has been proved that low notes, however loud, make no impression on the Bat, though a sharp clicking sound or the tearing of paper will alarm him at once.

Our Bats are all nocturnal in their habits, though a few indulge in occasional flights by day. Most of them have definite hours for flight, the time depending upon the flight period of the insects they prey upon particularly. They retire for the day into dark situations, such as hollow trees, caves, outhouses, or under roofs. In these sleeping places great numbers often congregate, and several species may be represented. During bad weather--when, of course, their insect prey also remains under cover--they do not leave their daytime shelter. When asleep their body temperature falls considerably. In harmony with this nocturnal habit we find that our Bats are usually dull coloured--some tint of brown with the underside lighter than the upper.

All the British species hibernate, and before the beginning of this period they develop a good deal of fat to carry them through it. On any day in the winter when there is any considerable rise of temperature they wake at once and look around for insects that have been aroused by the same means. The larger kinds usually eat their food as they fly, but the smaller Bats rest for a few moments for this purpose. The web between the legs and tail ("interfemoral pouch") is mostly used to hold their prey whilst it is being eaten. It also serves to receive the newly born young.

The young Bat is born blind, but not quite naked. It at once clings to its mother's fur by means of its claws, and by its teeth to her nipple. Nursing mothers appear to form colonies apart from the others. The growth of the young Bat is rapid and it is soon fully covered with fur. Before it is a fortnight old it is able to leave its mother temporarily, but it does not lead an independent life until it is about two months old. Nothing certain is known about the age to which a Bat attains, but it appears to be about four years.

Until the present century there was an astonishing lack of knowledge of the life-histories of our native species; but a small but enthusiastic band of observers have in recent years done much to make good the deficiency. In this connection the work of Messrs. Alcock, Coward, Moffat, Oldham, Tomes and Whitaker calls for acknowledgment. They have hunted far and wide, exploring the sleeping places and hibernacula, in woods, caves, roofs and belfries, and have established--among other facts--that our Bats are more numerous in the south, becoming scarcer as we go west, and that there are few species represented in the fauna of Scotland. Most of the species appear to be common in some one or more localities, even if rare elsewhere; and the physical features of a district have a striking influence on their local abundance or scarcity, certain species being more discriminative in this respect than others. The presence of woods, water, and caves appears to be the most favourable condition governing their comparative plentifulness or scarcity.

The Bats were known generically in Anglo-Saxon times as Flittermouse and Reremouse, and these names may be met with still in certain localities; but to the general public the Bat is still a Bat without distinction of species. Although there are twelve distinct kinds that breed in the British Isles, for each of which the naturalist has had to invent an English as well as an international name, not one of these has got into ordinary use; so that it is impossible to get any precise information from those whose occupation gives them opportunities for observation.

*Larger Horse-shoe Bat* (Rhinolophus ferrum-equinum, Schreber).

We have two Horse-shoe Bats, distinguished as Larger and Lesser, and they are regarded as the lowest organised of our Bats. Their distinguishing feature as a genus is the absence of the tragus from the ear, and the presence of a leaf-like outgrowth of naked skin on the muzzle around the nostrils. The broad forepart of this forms the horse-shoe, a protruding central portion behind the nostrils is known as the sella, and behind it an erect tapering portion is the lancet. There can be little doubt that this extraordinary expansion is no mere ornament, but a sense organ which enables these Bats to execute their marvellous flight through narrow passages. They are able even to distinguish invisible obstacles like glass, and they fly low down among bushes and herbage where they are far more likely to collide than in the upper air. In these respects their motions are different from those of the other Bats.

The Larger Horse-shoe Bat is a large and rather heavily built Bat whose proportions are only slightly exceeded by the Noctule (page 46), our largest species. The combined length of head and body is about two and a half inches, and of the tail an inch and a quarter. The forearm is two inches or more, and the expansion of the wings covers more than thirteen inches. The large ears are about half an inch broad, narrowing abruptly to the sharp recurved tip; when laid forward over the face they reach slightly beyond the tip of the muzzle. The lower portion of the broad wing membrane is attached to the ankle and the tail almost to the tip of the latter. The colour of the fur above is reddish-grey; on the underside pale grey. Its cry is a sparrow-like chirp.

The mouth has a straight broad opening below the swollen muzzle with its stiff moustache. The large canine teeth are very conspicuous in contrast with the small incisors. The dental formula for this and the next species is: i 1/2, c 1/1, p 2/3, m 3/3 = 32.