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.