Читать книгу Animal Life of the British Isles - Step Edward - Страница 6

Pl. 6.][C 18. Mole making a new burrow. When alarmed above ground it dives rapidly into soft earth.

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Pl. 7.][C 19. In the Mole's nursery. The young have wrinkled pink skin.

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Upon this Adams has the following comment:—

"With regard to a deliberate choice of 'the most favourable spot' after a survey of the cantonment by a practically blind animal of the Mole's impatient disposition and subterranean habits, there can be no question as to its absurdity."

The male and female (Boar and Sow) appear to associate only temporarily, the female being polyandrous and constructing her own nest-hill, which is smaller and of more simple plan than the male's winter retreat and seldom has a bolt-run. Her hunting tunnels are winding as compared with the long straight runs of the male. The nest is a ball of leaves and grass, all having to be carried in by the mouth. The chief pairing season is at the end of March and beginning of April, and the young are born about six weeks later. The number of young in a litter varies from two to seven, the average is three or four. They are blind, naked and pink, but before the fur has begun to appear the skin has darkened to a bluish slate-colour. The eyes open about the twenty-second day.

The Mole does not appear to be definitely hunted by any enemy—save man!—although killed by Weasels, Herons, Owls, Fox, and Badger when they come across him. Adams thinks that for all practical purposes the Mole may be considered blind; that if its eyes were not covered by fur the low position of its head would prevent it seeing beyond an inch or so. He is convinced that worms are hunted by scent. The Mole is an excellent swimmer, and can attain to a similar speed in the water to that of the Water Vole.

The Mole does not hibernate: the demands of his appetite appear to preclude the possibility of a long fast, even if dormant.

Old names, still extant in some districts, are Moldwarp, Moudiewarp, Wunt, Want (in the "Epinal Glossary" of about A.D. 700, spelled Wand). Its feet, carried in the pocket, are a rustic specific for rheumatism.

Though Adams refrained from eating adult Mole, warned as he tells us by the dark flesh and musky odour, he experimented with a couple of milk-fed young, ten days old, and had them boiled. Eaten without salt or other condiment, he says he "found them excellent, much like Rabbit, the flesh being white and very tender."

The Mole's position in human regard has always been equivocal. The gamekeeper has accused him of sucking partridge's eggs, and the farmer has pointed to his young wheat plants turned out of the ground as the Mole ran a surface furrow across the cornfield. Against this in former days the farmer would credit him with the wholesale destruction of earthworms; nowadays, however, the farmer has more enlightened views on the subject of earthworms, and their destruction must go into the debit side of the account. But the Mole does not live on worms alone, though chiefly: his runs must cross the track of many a grub—wireworm, leather-jacket, and fat cockchafer-grub, for examples, and slugs and snails on the surface—that the farmer would gladly have removed; and it is not likely that the Mole pushes such fare from him untasted. Then, again, one must remember the agricultural value of the little black engineer who carries out so efficient a system of surface drainage, and improves the pasture by bringing to the surface fresh soil from below. There is, however, no mercy shown, no redeeming virtue admitted, in the case of the Mole who sins against society by running his tunnels under the tennis-lawn or golf-green, and spoiling their levels by thrusting up his unsightly rubbish heaps. So enormous numbers are killed yearly; and the Mole-catcher boasts of his great annual catches. But the astute Mole-catcher refrains from destroying the nests, for were he to do so his occupation would be gone. The Mole squeaks much like a Bat or Shrew.

Pl. 8.][C 20. External view of Mole's Nursery. It is smaller and of simpler structure than the so-called "fortress."

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Pl. 9.][C 21. Common Shrew. Sorex araneus.

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The Mole appears to be plentiful in all parts of England, Wales and Scotland, wherever there are earthworms; it has been found even at an elevation of 2,700 feet. But it does not occur in Ireland, the Shetlands, Orkneys, Outer Hebrides, or the Isle of Man.

Colour variations have been recorded including cream, orange-pink, whitish with markings nearly black, orange or yellowish, as well as wholly grey, fawn or ash-coloured.

Common Shrew (Sorex araneus, Linn.).

Along the hedgebank, the ditchside and the edge of the spinney in the evening, may be seen one of the smallest and prettiest of our mammals, a minute dusky red-brown creature with long flexible pointed snout turned up ever and anon to reach an insect on the grass stems. Although he has bright bead-like eyes his range of vision is very short, and if we keep quiet and undemonstrative we can watch him without his being aware of our presence.

This is the Common Shrew or Shrew-mouse, an inoffensive and useful creature, for its food is restricted to insects, snails, woodlice and the other small fry that annoy man without the latter being able to do much in retaliation. As he sits there among the long-stalked trefoils and nodding flowers of the wood-sorrel we are able to get a good view of him.

With a combined length of head and body amounting only to three inches, his long hairy tail adds nearly half as much again—but the tail length varies a good deal in different individuals. His bilobed snout extends far beyond his mouth, and is well furnished with whiskers. His hind foot—a distinguishing feature in the Shrews—measures just over half an inch. He is clad in a coat of soft, close, silky fur whose dark upper part pales to dirty yellowish-grey beneath, and his hairy feet and tail are flesh-coloured. The dark coloration may vary to almost or entirely black. The hairs on the tail are short and stiff, almost like little spines. A gland on each flank, midway between elbow and thigh, provides the disagreeable musky odour which is its sole protection against enemies.

In winter he spends his time in hedgebottoms and copses among the dead leaves, but not in sleep as stated often. In summer he moves out into the fields and rough pastures, where there are tufts of coarse grass in which he can take cover, and from which he makes runs through the surrounding grass. Here he may be seen at times actually climbing the stout grass stems after insects; sometimes he climbs a tree. His toes are well separated, and this enables him to climb. Although the feet are not well formed for digging he can burrow expeditiously in light vegetable soil with the forefeet, and can bury himself in twelve seconds; but, as a rule, he is more inclined to utilise the common underground runs of Mice where these are available. The long, attenuated and sensitive snout, like those of the Pig and Hedgehog, are well adapted for turning over dead leaves and the surface soil in its search for insects, worms, and snails; and its short, soft, velvety fur fits it for passage through the soil without getting dirty. His movements are not nearly so rapid as those of the Mice, and it is consequently a better subject for observation. It is by no means an unusual sight to see it swimming, and in accordance with this semi-aquatic habit, it frequently makes its nest on the banks of ditches. The nursery is a cup-shaped nest woven of dry grass and other herbage with a loose roof beneath which the Shrew makes its entrances and exits. These are frequently uncovered by the mowers at haying time.

The breeding season extends from May to November, and during this period each female appears to have several litters, each consisting of from four to eight or even ten—but usually five, six, or seven—young, although she has only six nipples. Putting it at three litters of six as an average—eighteen in a season—we get an enormous possible increase of Shrew population. Yet the numbers observable from year to year are fairly constant; and in considering the high birth-rate we have to allow for the heavy bill of mortality. Though Shrew-flesh is not to the taste of all carnivorous creatures, and its musky odour makes it actually repellent to some, this does not in all cases protect the Shrew from death. Cats, for example, kill many Shrews, but will not eat one. Dogs also account for many Shrews, and will sometimes essay them as food, though their stomachs refuse to deal with the unpleasant musky morsel.

From the latter part of summer onwards dead Shrews are quite common objects of the countryside; and various theories have been set up to explain the phenomenon, for these dead bodies are mostly without any signs of maltreatment, either by tooth or claw. It has even been attributed to an autumn epidemic afflicting Shrews alone; and to the influence of fear caused by a thunder-clap or the mere breaking of a twig near by. But apart from this mysterious mortality, Owls levy a heavy toll upon the Shrew, as is evident from the indigestible "casts" thrown up by these birds. Other birds of prey, such as the Kestrel, are known to take their share, and a further considerable number are claimed by Magpies, Jackdaws, Stoats, Vipers, and Smooth Snakes. Then, again, numerous males fall victims to the jealous fury of their own sex, which leads to fierce and fatal battles. But, as already stated, there are seldom any indications of such encounters on the bodies of these autumn dead, and the only conclusion that appears tenable is that they have died from what a coroner's jury would term "natural causes."

Mr. Lionel Adams, who has made special investigations into this matter, suggests that the natural cause is senile decay. He points out that young Shrews moult before winter, the process beginning in September and being completed by November, getting a darker and thicker coat than the light brown one they have worn hitherto. The progress of the change can be watched. It begins on the lower part of the back and extends gradually to the neck, head and face. In spring this darker coat is exchanged for a shorter and lighter one. But in their second autumn there is no resumption of the winter garb! The natural span of a Shrew's life is fourteen months as the maximum; and Nature does not go to the expense of winter clothing for creatures that will not live to wear it.

So small a body as that of the Shrew does not appear to require much food to keep it going; but the character of the food counts, and apparently insects are not very sustaining. The insect-eater must pursue his prey almost incessantly. We have proofs of this in the ceaseless activity of insectivorous birds, the Mole, the Bats, and the Hedgehog—all insectivorous. Mr. Adams found that, in captivity, a Shrew would gorge for half an hour, then have to sleep for a similar period before renewing its feeding with the same energy. In this case the food was all provided and had not to be chased; and the Shrew was willing to eat the flesh and pick the bones of one of its own kind. In thirty-six hours it consumed food of various kinds equal to nearly four times its own weight. If food is not obtainable for a few hours, the Shrew dies. This excessive demand of the stomach causes the Shrew to be active both night and day. It is fond of carrion, and has frequently fallen a victim to traps baited with bread, cheese, nuts or apple; and, as Mr. Pocock reports, with plum-pudding. He sleeps with the long flexible snout tucked between the forelegs under the chest.

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.

Skeleton of Water Shrew.

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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.

Pl. 10.][C 28. Water Shrew. Neomys fodiens.

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Pl. 11.][C 29. Common Shrew. Female beginning to prepare her nursery nest.

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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.