Part 13

The breeding nest is a globular structure of dry grass, and is usually built in a separate chamber of the underground run, but occasionally is on the surface or under a heap of hedge débris. Some of the burrows may extend as much as three feet underground.

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Towards the end of last century, Mr. de Winton called attention to what was considered to be a new British mouse--the Yellow-necked Mouse (Apodemus flavicollis), distinguished from the Wood Mouse by its larger size, the head and body measuring four and a quarter inches, and the brown spot on the chest commonly found in the Wood Mouse developed into an orange cross whose arms are connected with the upper side coloration--described as golden brown. This is a feature that at once attracts attention where this form occurs; but there is another distinction out of sight--there being three additional bony joints in the tail, that is thirty instead of the twenty-seven in the tail of an ordinary Wood Mouse. Whether it is a really distinct species or the typical form of the Wood Mouse is at present open to question. It is found chiefly in the southern and eastern portions of England, but its distribution also includes Northamptonshire, Herefordshire, and Northumberland.

Other local races have been distinguished also as distinct species or sub-species under the name of Hebridean Field Mouse (A. hebridensis) with the white of the under parts tinted with buff; Fair Isle Field Mouse (A. fridariensis), like the Yellow-necked but without the collar; St. Kilda Field Mouse (A. hirtensis) with brown under parts; and Bute Field Mouse (A. butei), darker, with shorter tail and ears.

*House Mouse* (Mus musculus, Linn.).

The most familiar, the most widely distributed and most numerous of the mammals of our country, the Common or House Mouse, stands in little need of nice description. Although of a timid and retiring nature, it can on occasion exhibit not only bold familiarity, but actual friendliness to mankind to which it has been attached for ages, preferring to live in palace or hovel with human beings to the open-air life of woods and fields. Not that he is not to be found in the open air; but then it is mostly in the immediate neighbourhood of a house, where he can make his runs in ricks of corn--mountains of food. It is this easy method of despoiling man of his goods that caused the Mouse in ancient days to attach himself to the huge creature that is so impotent in ridding himself of small adversaries. The domestic Mouse is considered to have had its home, its place of origin, in Asia, whence it has spread to every part of the world where man has gone. In most cases, it may be presumed with safety, it has travelled cosily stowed away in his stores and merchandise, so that as soon as the human migrant has built himself a home he finds that the Mouse is in occupation, and demanding a share of his food. In spite of all his serious depredations, our literature teems with evidence that the victim has always retained some kindly feeling for his pretty four-footed oppressor.

For the sake of uniformity, let us say that the head and body of the House Mouse measure a little more than three and up to four inches, and the tapering, flexible, and sparsely haired, scale-ringed tail may slightly exceed that measurement. It has a pointed snout, the bright, bead-like eyes are black, the large, sensitive brownish ears are nearly half the length of the head, and the soft, brownish-grey fur is only a little paler on the under parts. Outdoor specimens are often more yellow-brown in coloration. As compared with the Wood Mouse we have this more dusky and uniform coloration, shorter whiskers, smaller eyes, stouter and less flexible tail, and shorter legs. The thumb of the hand is reduced to a mere tubercle.

It is very active and silent in its movements, emerging from a tiny hole in floor-board or skirting and gliding without sound over the floor, ascending with ease table-legs or walls, and then, if alarmed, springing with a prodigious leap back to its hole. Concrete floors will not suffice to keep it out of a house, for it will climb the outer walls and enter the upper windows, thence making itself secret ways to the lower floors behind woodwork or plastered walls, till it reaches the kitchen, the larder or the storeroom. Though it shows by its preferences that its natural rôle is that of grain thief, it will eat any kind of human food and much besides: in a word, it is omnivorous.

Its great success as a species is due to this adaptability and to its astonishing fecundity. It produces four or five litters during the year, each consisting of five or six, or even up to twelve, blind and naked young which develop so rapidly that in a fortnight they are capable of independence. At the age of six weeks they may begin to breed.

The House Mouse exhibits a considerable range of variation in colour, both darker and lighter than the type, and many of these variations have been bred from and their peculiarities perpetuated and accentuated in confinement as "fancy" mice. Of these the most familiar are the White Mice, really albinos with pure white fur, pink eyes, feet, and tail. There are also dark, nearly black variations, and spotted examples. Sometimes one is surprised at night to find that the house is tenanted by a musical mouse that runs up the scale in what appears to be an attempt at a little song. It has been ascertained, however, that these so-called singing mice are afflicted with a form of asthma, and the supposed vocal efforts are merely the manifestation of their physical trouble. We have had experience of musical mice in another way. For several nights in succession weird sounds came from the pianoforte which suggested that fairies were using it as a harp, twanging the wires instead of striking them with the hammers. An examination of the interior seemed to indicate the actual performer, for a little pile of Spanish nuts, stolen from the table, was discovered inside; and the twanging of the notes was caused probably by the mouse climbing them. A trap baited with a shelled nut put a stop to these performances. Bateson mentions several cases of hairless Mice, except for a few whiskers.

A local race of the House Mouse found in St. Kilda is sometimes dignified with species rank under the name of Mus muralis. Its distinguishing features include less slender feet and tail, and slight peculiarities of the palate.

*Black Rat* (Epimys rattus, Linn.).

Not many years ago a good deal of modified regret was expressed because it was thought that the Black Rat--the real old British Rat as it was called--was being exterminated by that vulgar upstart the Brown Rat--the Hanoverian or Norway Rat. These laments were mainly called forth by its comparative scarcity in old London warehouses where it had formerly been very numerous. One would have thought it a matter for rejoicing that there was a possibility of our having only one species of the rat pest to contend with instead of two. The disappearance of the Black Rat was remarked by Pennant as far back as 1778. However, later observations tend to show that the Black Rat is far from being extinguished even in the City of London, where the old type of warehouse is being rapidly replaced by ferro-concrete erections with carefully trapped drains. The intelligence of the Rat is equal to little impediments of that sort, and if it cannot get in by way of the basement it can climb walls and enter by the attic windows.

On the score of sentiment we need not distinguish between the Black Rat and the Brown. They are both Asiatic aliens, though the Black Rat had been settled here for several centuries before the Brown Rat followed in his tracks. Nothing definite is known as to the date of his arrival. Geologists assure us that he was not among the indigenes, for even the most recent strata yield no remains of his bones or teeth. He is known to have been on the other side of the dividing Channel in the thirteenth century, and to have reached England soon after, and quickly to have become a nuisance. He had a clear run of over four hundred years in which to occupy the most remote portions of the island, before he had to meet with keen competition in the form of the Brown Rat. He reached Ireland in the twelfth century, if not earlier.

The Black Rat is of more slender proportions than the better known Brown Rat, and much smaller, the dimensions of the head and body being about seven inches, whilst the scaly-ringed and almost hairless tail is more than eight inches. The long, pointed snout projects far beyond the short lower jaw; the whiskers are long and black. Though presenting the appearance denoted by its popular name, the glossy blue-black fur has a good sprinkling of grey on the upper surface, whilst below it is dark grey. The large, thin ears are naked, and about half the length of the head. The feet are pink, with scale-like rings on the underside of the digits and five pads on the sole. The thumb of the forefeet is reduced to a mere tubercle.

Although the Rats have much to do with garbage and offensive matters, they take the greatest of care to maintain their own cleanliness and a spruce appearance, spending much of their time in cleaning their fur and paws. One of the reasons for regretting the possible extirpation of the Black Rat by his more pushful relative, was, no doubt, his less ferocious ways and well-known milder disposition--a trait which is obvious to any one who has handled the domesticated albino, or White Rat, which is generally considered to be of this species.

Where--as in India--the Black Rat lives a more out-of-door life, it climbs trees and mostly makes its nest in them. With us the doe collects a good quantity of suitable materials--rags, paper, straw, etc.--and constructs a roomy nest which she uses for successive broods, which come at short intervals. Seven or eight is the usual number for a litter, and there are five or six broods in a year.

In the matter of food, both the Rats are omnivorous, and it is, therefore, useless to attempt to give a list of substances acceptable to them. Fish, flesh, fowl, or vegetable, crustacean or mollusc--anything that can be digested--is eaten by them; and if all else fails they will eat their own kin. In this matter the Brown Rat, from his superior size and ferocity, has the advantage, as is emphasised by an incident told by a professional rat-catcher to Frank Buckland. He said that having had a successful haul in infested premises he had turned all his captures both Black and Brown into a large wire cage, intending to have a little sport next day with a few cronies and a terrier or two. To his astonishment next morning all the Black Rats had disappeared and only the Brown--or some of them--remained.

A sub-species, the Alexandrine Rat (Epimys rattus alexandrinus), with brown back and dusky underside, is frequently introduced with shipping from North Africa, and has been recorded from Lundy Island and Shetland. Another sub-species, the Tree or Roof Rat (E. rattus frugivorus), common in the Mediterranean region, often appears in our ports. It has long, soft and dense fur, of light grey or brown on the upper parts and whitish below (pure white to pale yellow), and the feet usually white above.

The Black Rat is more of a climber than a burrower; more cleanly in its feeding than its brown rival. The pink-skinned young are born without fur, sight, or hearing.

*Brown Rat* (Epimys norvegicus, Erxleben).

The Brown Rat still has two alternative names applied to it, though the inappropriateness of one was shown by Pennant more than 150 years ago. These names are Norway Rat and Hanoverian Rat. Pennant does not mention the second, but of the first he says that the Brown Rat is quite unknown in Scandinavia and is not mentioned by Linnæus. The name Hanoverian appears to have been given to it because it was believed to have made its entry into England with George I. Writing in 1776, Pennant says: "This animal never made its appearance in England till about forty years ago." Recent researches into its distribution make it appear that the species originated in Trans-Baikal, whence it has spread westwards, even to America by way of the British Isles. Both species hit upon an improved method of extending their range over the earth. The old-fashioned natural way for mammals to spread was for a few adventurous individuals to make food-finding excursions beyond the district in which they were born; but climate, mountain ranges, broad rivers or seas often checked further progress. The Rats discovered that by keeping close to man they were always in the neighbourhood of food, whether intended for himself or his domestic animals; and even these tame creatures would at times serve for the Rats' meals. So when they found man loading ships with grain and other desirable food they decided to go with him. Often they contrived to get into his bales of merchandise and so conveyed to the hold. If not, there were always mooring ropes which served as bridges from the quay to the vessel. And so they got themselves conveyed in comfort, sure that wherever the goods went there would be settlements of their biped friends to house them and serve their ends generally. Now, wherever man has established himself, you are almost certain that the Rat is close at hand.

Mr. A. W. Rees, in his interesting "Creatures of the Night," has summarised the chief characteristics of this species in a paragraph. He says: "Brown Rats are an insufferable nuisance. There is no courtesy or kindness in the nature of the Rat; no nesting bird is safe from his attacks, unless her home is beyond his reach in some cleft of a rock that he cannot scale or in some fork of a tree that he cannot climb. He is a cannibal--even the young and the sick of his own kind become the victims of his rapacious hunger--and he will eat almost anything, living or dead, from the refuse in a garbage heap to the dainty egg of a willow-wren in the tiny, domed nest amid the briars at the margin of the river."

As compared with the Black Rat he is more heavily built, and the combined length of head and body is eight or nine inches, whilst the thicker, scaly-ringed tail is only equal to, or less than, the length of the body alone. His head is proportionately shorter, with blunter muzzle, much smaller ears and more prominent though smaller eyes. The fur on the upper parts is grey-brown with a tawny tinge, and dirty white on the under parts. The ears, feet, and tail are flesh-coloured. It sometimes occurs with black or blackish fur, and is then frequently mistaken for the Black Rat; but the relative length of tail to body is a superficial character by which they can be separated at once. There is a black race of this species on the east coast of Ireland to which some authors have given the distinctive name of Epimys hibernicus. It appears to have extended its range from Ireland to the Hebrides. In one form or other the Brown Rat has extended to nearly every part of the British Islands and their islets.

The Brown Rat becomes a parent at the age of six months, and produces four or five litters in a year. Ordinarily these consist of from four to ten blind, deaf, and naked young; but much larger litters are on record, the highest of which we have seen a note being twenty! Sometimes the young grow up hairless or blind. Some years ago we disturbed a nest in the garden from which issued half a dozen young Rats about four inches long (head and body), all blind. They moved about in a very uncertain manner, and were easily despatched. Similar cases have been recorded. At the meeting of the Zoological Society in December, 1902, a hairless Rat was exhibited on behalf of Mr. G. A. Doubleday, one of three captured at Leyton, Essex, in the same condition. The skin, which was slate coloured, was wrinkled into folds all over the body. Millais mentions a hairless Rat with yellow skin.

In the country--where it is known as the Barn Rat--the Tawny Owl and the Weasel are the farmer's best friends as Rat-catchers, though they do not always get the consideration that their services merit. The Weasel tribe are admittedly also destroyers of poultry; but the depredations of the Rat in this connection are much more serious. They do much mischief in chicken-runs, and being good swimmers and divers, even ducklings afloat are not safe from them. If a pair of ducks have made their nest on an island for safety, rats will swim to it and feast on the eggs, or, should these be hatched, kill the ducklings and eat them. It is more than probable that much of the destruction of pheasant and partridge eggs debited to the account of the Hedgehog, has really been carried out by the Rat. Jordan ("Forest Tithes") says he has known a Rat or Rats take a dozen eggs from a wild duck's nest and bury them in the soft peaty bottom of a moorland runnel, close to the nest. "I traced the whole proceeding and dug the eggs out with my fingers."

It does not matter where it is living, in town or country, the Rat is equally destructive to property and live stock. We have known them to destroy a crop of garden peas by ascending the pea-sticks, night after night, lacerating all the pods that had fair-sized peas within, and eating out every one. They skulk along the hedgerows until they reach the "cave" where the farmer has stored his mangolds to secure them from frost. Scores of them will burrow through the cover of earth and eat their fill of the succulent roots. Well is it for the farmer if the Weasels have not been exterminated on his land, for they are the most efficient guardians of his hoard. Hawks and Foxes render similar service if the Rat wanders out into the open moorland; but the Rat rarely ventures far from cover of some sort.

There is a melanic or black form of the Brown Rat which is frequently mistaken for the true Black Rat, though the more bulky build and blunter muzzle should show the difference at sight. First recorded from Ireland in 1837, it was considered a distinct species under the name of the Irish Rat. Its fur is uniformly dusky above and below, and the skin is of similar hue. The variation is now known not to be confined to Ireland, but to occur in many parts of England and in the Outer Hebrides. White, fawn coloured, and pied variations also occur.