Part 3

The Shrew's dental formula is i _4/2, c 1/0, p 2/1, m 3/3 = 32_. The summits of the teeth are red-brown, and the almost horizontal lower incisors are encircled by those of the upper jaw.

The Common Shrew is found throughout Great Britain but not in Ireland. Its vertical range is from sea-level certainly to 1500 feet, at which height it has been found in Cheshire by Coward and Oldham. It probably goes higher in our mountain regions, for on the Continent it has been recorded at 6000 feet. It is active all the winter among the dead leaves in some thick hedgerow, where it searches for hibernating insects which are plentiful in such covers. The rambler at this season may have his attention called to the Shrew by its shrill squeak, but like that of the Bats it does not impress all ears.

A form found in the Isle of Islay has been separated as a distinct species under the name of _Sorex granti_.

It is strange that so inoffensive a creature should have been the subject of superstitious malignity in the past. It was reputed to cause lameness by merely running over the foot of man or beast, and as an antidote a Shrew was plugged into a hole bored in an ash tree from which thereafter a twig passed over the afflicted part would effect a cure. Readers of Gilbert White will remember his description of the Shrew-ash that formerly stood "at the south corner of the plestor" at Selborne. The evil reputation of the Shrew was much more ancient than White's day, for the Rev. Edward Topsell, who wrote a "Historie of Four-footed Beastes" (1607), says of it--"It is a ravening beast, feigning itself gentle and tame, but, being touched, it biteth deep and poysoneth deadly. It beareth a cruel minde, desiring to hurt anything, neither is there any creature that it loveth, or it loveth him, because it is feared of all."

*Lesser Shrew* (_Sorex minutus_, Linn.).

The Lesser or Pigmy Shrew is the smallest of all British mammals. It may be described roughly as a smaller edition of the Common Shrew, and until recent years was considered to be only the juvenile form of that species, for which, no doubt, it is still mistaken frequently. It appears to be widely distributed in Britain, but is local, the areas in which it occurs being limited and patchy when marked on the map. These are mostly in wooded districts, but extend from sea-level to the tops of our highest mountains, for it has been found on Ben Nevis at a height of 4,400 feet. In Ireland, from which the Common Shrew is entirely absent, its place is taken by the Lesser Shrew, though it is not nearly so abundant as the Common Shrew is in Britain.

Seen side by side these two species are sufficiently distinct, but apart they may be taken as identical. The earlier British naturalists had not learned to discriminate one from the other, and even Bell, as late as 1837, does not mention the Lesser Shrew, though in the second edition of his work (1874) it appears in a description by Alston. If we take average length of head and body in an adult Common Shrew as three inches, we shall find that a similar individual of the Lesser Shrew measures only two inches and a quarter--a reduction of 25 per cent. The hind foot without the claws in the Common Shrew is half an inch, but in the Lesser Shrew it is one-sixth less. The actual length of the tail is about the same in both species, but proportionately there is a difference, for whilst that of the Common Shrew only equals half the length of head and body, in the Lesser Shrew it is equal to two-thirds. But it has been held that the length of the hind feet alone is distinctive, and that "any Shrew in which these reach or exceed 12 millimetres may be set down as of the larger species."

The colour of the fur is the brown and white of the common species with a fairly sharp line of demarcation between them. Though the animal as a whole is more delicately built, the snout is relatively longer and thicker; the tail also thicker and more hairy; the forearm and hand are shorter. The sensitive snout appears to be more useful than its eyes in hunting. As the result of his experiments, Adams is of opinion that the sight of Shrews is not much--if at all--better than that of the Mole. Yet it must hunt incessantly for, owing to its rapid digestion, frequent meals are a necessity. It is so delicately organised that it has been found that detention in a trap for only a few minutes is fatal to it; and captured specimens that have been carried in the hand for a few hundred yards have died shortly after.

It is an excellent climber, and sometimes enters the upper windows of houses. It is more nocturnal in its habits than the Common Shrew; but is subject to the same autumnal mortality. It does not appear to construct burrows, but utilises those of Mice. Its nests have been found in various situations, such as a clump of rushes, a hollow tree stump or a hollow in the ground roofed by a stone; and they have been of different materials according with the local conditions, moss, dry grass, fine rush shreds and wood chips variously combined and interwoven to form a hollow ball.

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_.

As already indicated, the flight of this Bat is usually low, and it alights to consume its prey, which it presses against the wing membrane, the interfemoral pouch not being large enough for the purpose. Its food consists chiefly of the larger beetles, such as cockchafers and dor-beetles, the quick-running ground-beetle _Pterostichus_, moths, flies, bees, and caddis-flies. It appears to be a thirsty creature, and may be seen lapping water. It takes its daytime sleep in caves, dark buildings, lofts and roofs. It may hang singly or crowd into crevices. Mr. Coward found it in the Cheddar caves hanging in bunches. Their overhead resorts are revealed by heaps of excrement below. Their natural resting attitude is hanging by the feet head downwards. They cannot walk on a flat surface, and before alighting on a vertical one they turn a somersault in the air to get the proper position. Their senses are so acute that Mr. Chas. Oldham says: "Even when sunk in winter sleep they appreciate a man's approach. The eyes are, of course, then shrouded by the wings, and the sense of danger must be conveyed to them either by hearing, smell, or, as seems to be most probable, by the exercise of their extraordinary tactile sense, which enables them to actually feel the approaching danger."

There is but one young at a birth, which occurs at the end of June or in July. Its eyes are closed, and the underside is quite naked and the skin purple. The eyes open about the tenth day.

The Larger Horse-shoe Bat has an extensive distribution. From England it is found through Central Europe and the Mediterranean region, through the Himalayas to China and southern Japan. In our own country it is found chiefly in the South-west of England, South and West Wales, but does not occur in either Scotland or Ireland. The presence or absence of caves suitable for a winter retreat appears to have some bearing upon its distribution.

*Lesser Horse-shoe Bat* (_Rhinolophus hipposideros_, Bechstein).

The Lesser Horse-shoe Bat is much smaller and more delicately built than the species last described. The nose-leaf has a narrower outline and its sella is more wedge-shaped; the lancet slender with a wedge-shaped tip. The expanse of wings is less than ten inches, and the length of the forearm is only an inch and a half. The colour is much the same as in the larger species, but somewhat darker above and more yellow below. Its habits are similar also, but, naturally, it does not hunt such large beetles, nor does it fly so low. It has a more fluttering flight with intervals of gliding. Its "tchek-tchek" cry is of lower pitch than in most Bats, and Oldham compares it to a diminutive of the alarm-note of the Greater Spotted Woodpecker.

The single young one is born somewhat later than in the last species: it is born like the other with a thin coat of downy hair on the upper side only.

Males, apparently, are more numerous than females.

The species appears to be more abundant in localities where there are caves which provide it with the equable temperature it requires in hibernation. It is most susceptible to wind, and will frequently remain inactive in its shelter because there is wind outside. Even tame individuals exhibit a strong desire to get into the most retired corners and crevices. The first recorded British example was taken in a cavity over a baker's oven to which it had obtained access through a small fissure.