Part 9

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.

The versatility of the Brown Rat is such that it would be idle to attempt any description of its habits. Every one knows at least some part of the story, and the whole of it would require a book. It is the most powerful natural enemy that civilised man has had to contend with, for it attacks him in his own strongholds, spoiling and wasting his food stores and destroying his property in general. There was a time when it could be looked upon more as a commensal because of the valuable scavenging work it performed; but since man has learned that it is safer to attend to this work himself the Rat has become a mere parasitical nuisance. Sir J. Crichton-Browne has estimated the annual loss to this country through the depredations of Rats at £15,000,000 (pre-war figures, 1908).

The Rat is so thoroughly omnivorous that it would be equally absurd to attempt a list of its food: there is nothing that can be eaten that the Rat will not eat. Therefore, there is no possibility of starving him out. Rat-killing campaigns that do not cover every square yard of the country can only have the effect of temporarily mitigating the nuisance; for the Rats' fertility is so great and so rapid that the loss of nine-tenths of a generation is quickly made good. A continental statistician has worked out the theoretical progeny of a single pair of Rats after ten years as reaching the appalling figure of 48,319,698,843,030,344,720! Of course, there is no great value in such a calculation, for it proceeds upon the assumption that every individual lives to become a parent, whereas in fact the mortality in all creatures of such fecundity is enormous, and there are few if any more survivors this year than there were last year. In other words, the great fertility of a race only suffices to make up the wastage from enemy attacks. But the figures serve to show what might happen if the natural control by Weasels, Stoats, Hawks, and Owls were suspended for a short time. But Rats are disseminators of bubonic plague with the aid of their special species of flea.

*Water Vole* (_Arvicola amphibius_, Linn.).

In certain directions it appears that failure is the lot of those who have spent the greater part of their lives in trying to spread enlightened views as to the true nature of our native animals and plants. Among a number of such failures two or three may be briefly cited here: you cannot persuade a countryman that a slow-worm is not a snake, that all snakes are not poisonous and to be killed at sight, and that the comparatively inoffensive rodent now to be described is not a rat and of rat-like nature. The name of Water Rat is general as a true folk-name.

The Voles are of heavier build than the Rats, the head is shorter, thicker, and the muzzle rounded instead of being pointed; the limbs are shorter and the hairy tail is not much more than half the length of the head and body. The eyes are small and short-sighted, and the small round ears scarcely project from the surrounding fur, though when listening intently the Vole erects them and makes them more conspicuous. Linnæus, following Ray, described the Water Vole as having webbed feet, but this is incorrect, though the toes of the hinder foot are connected at their base. They are naked and pale pink beneath, with five rounded pads, but above are clothed in stiff hairs. The thick, long, glossy fur is of a warm reddish-brown above, sprinkled with grey, and on the under parts yellowish-grey. This applies chiefly to the male; the female is slightly smaller than her mate, is less bright and more greyish-brown in her coloration. The average length of head and body is seven and a half inches, and of the tapering, ringed tail about four and a half inches. It sometimes occurs with black fur, especially in East Anglia and Scotland; and these examples are usually reported as the Black Rat. Some modern authorities recognise it as a sub-species (_reta_).

Although it has not the webbed feet that Ray attributed to it, its swimming and diving powers are of a high order. Often in walking near a stream or pond, the loud sudden "plop" as it drops into the water is our first intimation that the Vole is near. We may occasionally track his course under water, but as a rule he at once disappears into his burrow in the bank, sometimes by an under water entrance, and may regain the bank by an upper exit. These burrows, in which the Vole spends most of the daytime, often occasion considerable damage, as to the dykes in the Fenland, and where ponds have been constructed by artificial banking. Otherwise, the Water Vole must be pronounced an entirely inoffensive rodent, in spite of the libels that accuse him of capturing waterfowl and fish for which he is unfitted. He has been seen grubbing among the mud at the bottom for caddisworms and other insects, freshwater snails and the like; otherwise his food appears to be restricted mainly to the stems of horsetails and the succulent grasses, flags, loosestrife, and sedges that grow along the banks. Mr. A. Patterson says that in East Anglia he eats dead fish and living swan-mussels--also crayfish; but prefers the stems of the succulent grasses that grow in shallow ditches. That he is not a strict vegetarian appears to be proved by the fact that he is sometimes captured in rat-traps that have been baited with meat. St. John says that in spring, before the grasses are much grown the Water Vole feeds largely upon toads, rejecting the feet which it bites off and leaves in little heaps. We have been assured by a Surrey woodlander of long experience and an intelligent observer, that he has known the Water Vole on several occasions to indulge in very young chickens; but he admits this is a very rare occurrence and that it scarcely detracts from the Water Vole's reputation as a vegetarian.

On the flanks, about halfway between the shoulder and the tail, will be found a pair of wrinkled glands which secrete a greasy matter with a musky odour. These are present in both sexes. Though the odour probably protects the Water Vole from some animals that might otherwise prey upon it, it does not appear to be objectionable to the Heron, the Owl, or the Stoat. When, to escape from real or fancied danger on land it suddenly dives into the water, it is not always to safety, for pike, large trout, and eels have been observed to seize them.

The Water Vole does not hibernate; but it has been said to lay up considerable stores for the inclement season when food will be scarce and difficult to find. These stores consist of nuts, beech-mast, acorns, and the creeping underground stems of the horsetails. During the milder nights that come in winter he issues from his chamber in the bank and feeds upon young willow shoots; and though mainly a nocturnal animal will often take advantage of the higher temperature at midday during the winter. It is often found in fields far away from any water.

The female constructs a thick-walled globular nest of reeds and grasses in the chamber under the bank, or in a hollow willow or a bird's nest, and there brings forth her litter of about five (two to seven) naked and blind young. The process is repeated three or four times during the season.

The Water Vole is generally distributed in Britain, but does not occur in Ireland, or the Scottish islands; nor is it known outside Britain.

The surface of the molar teeth in all the Voles presents a pattern of alternating triangular prisms. In the Water Vole and the Field Vole these teeth are not rooted in the jaw; in the Bank Vole they are in the adult.

In addition to the definitely black sub-species (_reta_) referred to above, the southern brown sub-species occasionally throws up black, pied, or albino variations.

*Field Vole* (_Microtus agrestis_, Linn.).

To country folk the Field Vole is known generally as the Short-tailed Field Mouse, to distinguish it from the Wood Mouse which is also the Long-tailed Field Mouse. Being different in organisation from the true Mice the attempt was made in natural history works many years ago to substitute the name Vole for these blunt-muzzled Rodents. Recently, after about a hundred years' use of the word Vole in all the works on mammals, Mr. Barrett-Hamilton has objected to it, at least in connection with the present species, on the ground that Field Vole is a duplication, the word Vole meaning "field." This would be almost as bad as Mr. Barrett-Hamilton's own use of such scientific names as _Pipistrellus pipistrellus_, _Barbastella barbastella_, _Martes martes_, and _Capreolus capraea_, which are duplications in the same language! In East Anglia this species is the Marsh Mouse, and in Surrey Dog Mouse.

The general appearance of the Field Vole is so different from that of a Mouse that it should be obvious at a glance that they are not very closely related. The general stumpy form with the blunt oval outline of the head, the short, round ears just protruding from the reddish-brown fur, and the short, rather stiff tail, are points sufficient to distinguish it from either of our Mice. The colour mentioned refers to the upper parts; on the underside the fur is greyish-white. The hind feet have six pads on the under surface as compared with the five of the Water Vole. The length of head and body is about four inches, and of the tail only an inch and a quarter, that is, about a third of the body length.

The chief resorts of the Field Vole are meadows and damp pastures, but it will also be found in gardens, orchards, and plantations, doing enormous damage in every place, for its food is mainly of a vegetable character. It must, however, be placed to its credit that it catches and consumes large numbers of insects, among them the destructive Larch Sawfly (_Nematus erichsonii_). It has extensive underground stores where it lays up food for the winter; but it is a mistake to say, as it has been said repeatedly, that the underground burrows include its summer nest. These burrows connect with a network of above-ground runs through the grass and herbage, with occasional holes that enable the Vole to bolt underground. These runs are made without disturbing the grass blades, which cross above them and so enable the Vole to run or creep along them without being seen by the hawk that circles high overhead. He is not so successful in eluding the Owl, who hunts much nearer to the ground and with the Weasel keeps a salutary check upon its increase. Beside a rank tuft of grass along one of these runs the female makes her nest, roofed with a circular dome of grass blades divided longitudinally and plaited and felted. It very much resembles the ground-nest of the Humble-bee, but on a much larger scale. There is nothing to distinguish it from its surroundings, so that only an eye trained to find it would see it. It may be detected by the finer character (due to shredding) of the grass. The parent enters or emerges from any point under the edge of the dome, and in the case of our uncovering the nest will at once bolt, leaving her five youngsters at our mercy. This we have found to be a characteristic callousness on her part. We have frequently torn off the roof of such nests suddenly, but have only been able to catch sight of the rapidly moving mother and trace her for a short distance along a run, so unhesitating and rapid was her flight. Like all our Rodents with the exception of the Hares, the young are naked and blind at birth, and there may be five, six, or seven in a litter. Those shown in the photograph, though their eyes were not open, had beautiful coats of short fur. There are several litters in a season.

In those districts where the over-zealous efforts of the gamekeeper have resulted in the partial extermination of the Weasel and the Owls, the increase of the Field Vole is so enormous and so rapid that they have at times become a plague. Crops are cleared from the fields, young trees in plantations destroyed by thousands, and even newly sown cornfields rendered unproductive by every seed being eaten. In the New Forest and the Forest of Dean great loss has been sustained at various times by their severing the roots of young trees that crossed their runs, and by their gnawing the bark of the young trunks. The most effective of the plans adopted for lessening their numbers was by sinking pits a foot and a half deep, wider at the bottom than at the mouth, into which vast numbers fell and from which they could not escape. More recently the South of Scotland suffered from a plague of "mice" that ate up everything in the fields, inflicting such serious loss to agriculture that a Government Committee was appointed to inquire into it, and it was found that the chief culprit was the Field Vole. Fortunately, when things were at their worst, a vast number of Short-eared Owls appeared upon the scene and feasted royally until there was scarcely a Vole to be found. It was found that the enormous increase in the numbers of the Voles was directly due to the warfare waged by keepers on Weasels and Owls. Matters are better, perhaps, to-day; but there are still too many keepers who destroy as vermin the very agents that keep down the real vermin. We still need a few landowners of the temper of Charles Waterton, who threatened to strangle his keeper if the latter molested a certain pair of Owls.

It was also shown at the Vole Committee of 1893, referred to above, that the Rook destroys great numbers of Field Voles--not only adults that chance to cross the fields where the Rooks are digging cockchafer grubs, but that they systematically search for the nests and eat the young.

As in the case of the Wood Mouse, there are several local races of the Field Vole that have arisen in the islands of the Orkneys and Hebrides, which have been elevated into distinct species by some recent authors. Thus, there are recognised the Hebridean Vole, the Orkney Vole, the Sanday Vole, and the Westray Vole. Mr. Barrett-Hamilton regards the true _agrestis_ of Linnæus as not occurring in this country, where it is represented by several sub-species. The Common Field Vole described above, he says, is a distinct species, the _M. hirtus_ of Bellamy. This, which he describes as "a newer, smaller form," he says "has replaced an older, larger _M. agrestis_, the latter now confined chiefly to northern regions, and with isolated southern colonies on the mountains." Seeing, however, that most modern authorities agree in retaining the Linnean name, we have considered it advisable to do so also.

The form that Barrett-Hamilton recognises as _M. agrestis_ and calls the Northern Grass Mouse, is, so far as Britain is concerned, represented only in Scotland and its western islands by five sub-species which he names as under:--

Macgillivray's Grass Mouse (_M. agrestis macgillivraii_), a rich buff coloured form with thin fur, restricted to Islay, where it is rare.

Hebridean Grass Mouse (_M. agrestis exsul_), common on several islands of the Hebrides. Distinguished from the Field Vole by its much larger size and duller brown colour.

Eigg Grass Mouse (_M. agrestis mial_) restricted to the island of Eigg. Differs from _M. a. exsul_ in its shaggy coat of abundant long hairs.

Highland Grass Mouse (_M. agrestis neglectus_) found on the summits of the highest Scottish mountains. It is larger than the Field Vole, with thicker fur and darker, browner upper side. It differs from _M. a. exsul_ in the simpler character of the first molar tooth.

Muck Grass Mouse (_M. agrestis luch_), of which only three specimens have been taken, all on the island of Muck. About the same size as the Field Vole, it has a buff underside.

*Orkney Vole* (_Microtus orcadensis_, Millais).