THE FIELD-MOUSE.
This animal sometimes called the mulot, is less than the rat, but larger than the common mouse. It is not to be found in houses, but lives in woods and fields. It is remarkable for its large and prominent eyes; and it differs also from the rat and mouse in the contour of its hair, which is tolerably white under the belly, and a reddish brown on the back; they are very generally and abundantly diffused, especially in hilly countries. They appear to be a long time in attaining their full growth, as they vary considerably in size. The largest are better than four inches in length, and the smaller, which appears to be aged, are an inch shorter; and as they are found of all the intermediate sizes there can be no room to doubt their being the same species. It was probably from ignorance of this fact that some naturalists have distinguished them into two species, calling the one the Great Field Rat, and the other the Field Mouse. Ray, who first fell into this error, seems to acknowledge himself unacquainted with any more than one species; and though the short description he gives of two species appear to differ, yet we ought not to conclude that both exist, first, because he himself knew but one; secondly, because we know only one, and notwithstanding all my researches, I have been enabled to discover but one kind; thirdly, because Gesner, and other naturalists, speak only of one, under the name of mus agrestis major, which they affirm to be common; and because Ray says the other kind, which he calls mus domesticus medius, is also very common; it is therefore impossible but that one or other of these authors must have seen both since they declare they are both common; fourthly, because as in this same species large and small individuals are found, that circumstance might lead them to consider the former as one, and the latter as another; and, lastly, because the descriptions of these two pretended species are in no respect complete; and we ought not to trust such vague characteristics to establish a specific difference.
The ancients, indeed, mention two species, the one under the denomination of mus agrestis major, the other under that of mus agrestis minor. These two species are very common, and we are as well acquainted with them as the ancients were; the first is our long-tailed field-mouse; and the other, known by the name of the short-tailed field-mouse, but as it materially differs both from the rat and long-tailed field-mouse, I have not followed the generic appellation, but adopted that of the Italian, and call it campagnol.
The long-tailed field-mice, as we have already intimated, are fond of dry and elevated grounds. They are to be found in great numbers in woods and in adjoining fields. They conceal themselves in holes under brush-wood, or trunks of trees, which they find already made, or which they dig, in which they amass such quantities of nuts and acorns, that a bushel has been found contained in one of them; and this provision is not proportioned to the wants of the animal, but to the capacity of the place allotted for its reception. These holes are generally more than a foot underground, and often divided into two cells, the one for living in with their young, and the other as a granary. I have often witnessed the considerable damage done by these animals in plantations. They will follow the furrow of a plough and take up all the new-sown acorns, which they convey to their holes; and in a nursery of trees they are more destructive than all the birds and other animals put together. The only method I could ever find to prevent this evil, was to set traps at every tenth pace distance, through the whole extent of the new-sown ground. No other bait is necessary than placing a roasted nut under a flat stone, supported by a piece of stick, to which the nut must be fastened; this they are very fond of, and will come eagerly to seize; but no sooner do they touch it than the stone falls and crushes them to death. I have made use of the same expedient against the campagnol, which is also very destructive. When I first adopted this method, I desired care might be taken to bring me all the animals that were caught in the traps, and it was with astonishment I found more than 100 were taken daily, and this in a piece of land consisting of not more than 40 acres. I obtained more than 2000 in this manner, from the 15th of November to the 8th of December; their numbers afterwards decreased gradually, till the hard frosts commenced, when they retire to their holes, and feed upon what they have collected. A number of years have elapsed since I first made this experiment, and which I always repeated when I sowed trees, and never had reason to complain of its inefficacy. It is in autumn they chiefly abound; in spring they are not so numerous, for if their provisions run short during the winter the strong devour the weak; they also eat the short-tailed species, and several sorts of birds, beginning always with the brains and finishing with the rest of the body. I once put a dozen of these field-mice in a cage, and accustomed them to be fed every morning by eight o’clock; but neglecting them one morning for about a quarter of an hour, one of them had been eaten by the rest; next day they devoured another, and in a few days only one remained; the others having been killed and in part devoured; even the one that survived had his legs and tail mutilated.
The rat multiplies very fast, but the increase of the long-tailed field-mouse is more considerable. The latter brings forth more than once a year, and generally nine or ten at a time, while the rat seldom produces more than five or six. A peasant, on my estate, took twenty-two out of one hole, consisting of two dams and twenty young ones.
This animal is very generally diffused over Europe. It is found in Sweden, and is called by Linnæus, mus cauda longa, corpore nigro flavescente, abdomine albo. It is very common in France, Italy, and Switzerland. Gesner calls it mus agrestis major. It is also in Germany and England, where it is called the field-mouse. Its greatest enemies are the wolf, fox, marten, birds of prey, and its own species.
THE WATER-RAT.
This animal is about the size of a common rat, but in habits and disposition more resembles the otter than the rat. Like the otter it frequents fresh water; is found on the borders of rivers, rivulets, and ponds, and seldom feeds on any thing but fish, though he will sometimes eat frogs, water insects, and even the roots of plants. He has not, like the otter, membranes between his toes; an error which originated with Willoughby, and has been copied by Ray and other naturalists. Though every toe is separated, he swims with facility, keeps a long time under water, and carries off his prey to eat upon the grass or in his hole. Sometimes he is surprised in his hole by fishermen who are searching for craw-fish, whose fingers he bites, and then plunges into the water as his only place of refuge. His head is shorter, his nose broader, his hair more erect, and his tail much larger than the common rat. Like the otter he avoids large rivers, or rather those which are too much frequented. The dogs pursue it very furiously. He is never found in houses or barns, nor does he wander so far from the borders of the waters as the otter, which is sometimes found at a league distant upon land. The water-rat does not frequent high grounds nor dry plains but in moist and marshy valleys they are very numerous. The females come in season about the close of winter, and bring forth in April, generally having six or seven in a litter; they may probably bring forth oftener than once a year, but of this we have no certain knowledge.
Their flesh is not absolutely bad, being eaten by the peasants in catholic countries during Lent, as well as that of the otter. This species is found throughout Europe, the very extremities of the north excepted. If Bellon may be believed they inhabit the banks of the Nile, but the figure he gives of it has so little resemblance to our water-rat, that there is great reason to suppose them different animals.