*Water Vole Swimming.*
This fine swimmer is making for his burrow in the bank.]
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_).
[Illustration: _Pl. 66._ _H 102._
*Water Voles fighting.*
Arvicola amphibius.]
[Illustration: _Pl. 67._ _H 103._
*Young Field Voles.*
Average litter of five; eyes still closed.]
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.
[Illustration: _Pl. 68._ _H 106._
*Nest of Field Vole.*
The dark run at left connects with the nest at right.]
[Illustration: _Pl. 69._ _H 107._
*Field Vole.*
Microtus agrestis.]
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.
[Illustration: _Pl. 70._ _H 108._
*Orkney Vole.*
Microtus orcadensis.]
[Illustration: _Pl. 71._ _H 109._
*Bank Vole.*
Evotomys glareolus.]
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).
So far back as 1805 the Rev. George Barry, in his "History of the Orkney
Islands," mentions a rodent that was known locally as the Vole Mouse,
which he believed to be the same as the _agrestis_ of Linnæus. He says
it "is very often found in marshy grounds that are covered with moss and
short heath, in which it makes roads or tracks of about three inches in
breadth, and sometimes miles in length, much worn by continual treading,
and warped into a thousand different directions."
Towards the end of last century Mr. J. G. Millais obtained specimens,
and on a critical examination found that they differed from the known
forms in several details of skull structure and in the folds and angles
of the teeth, sufficient in his opinion to constitute a new species,
which he called _Microtus orcadensis_. It is larger than the Field Vole,
with a longer and slightly broader head.
It was found subsequently that specimens from different islands in
the Orkney group showed differences due to their segregation over
a long period, and they have consequently been distinguished as five
sub-species. These differences are minute, and it would be wearisome
and out of place in a popular work such as the present to detail
them. Generally speaking, they are much alike, and their habits are
practically identical, so far as at present known.
The runs are a conspicuous feature of the islands, among the heather
and the rough vegetation of the fields and hillsides, running along the
surface and at intervals entering tunnels about two and a quarter inches
in diameter--just sufficient to clear the spread of the Vole's whiskers.
Their nesting places, like those of the Mole, are under small mounds
connected with a network of runs. The nest itself is made of grass and
roots in a rounded chamber, where at intervals during the spring and
summer several litters, varying from three to six, are produced. Before
they are three weeks old they are capable of independent existence, but
for a time are still guarded by the mother.
The Orkney Vole appears to be specially fond of the roots of Heath
Rush (_Juncus squarrosus_), but also feeds on grass and the crops in
cultivated fields to which they can gain access. Mr. Millais found that
in cold weather his captive Voles became inactive. It has many enemies
to hold its increase in check, for every bird and beast large enough to
capture it will eat it readily.
*Bank Vole* (_Evotomys glareolus_, Schreber).
There can be little doubt that in many places the Bank Vole has been
mistaken for a bright variation of the Field Vole. Its habits are much
the same, except that it haunts the hedgerow and wooded country rather
than the open fields. As to the differences between the two species, the
Bank Vole's head and body measurement is only three and three-quarter
inches against four inches in the Field Vole, but its tail is actually
(not merely proportionately) longer, being nearly half the length of
head and body, and ends in a pencil of hairs. The ears and feet are
proportionately larger, the former also being more oval than round. It
further differs from the other Voles in the fact that the molar teeth
become rooted in the jaws of the adults. The fur of the upper parts is a
bright chestnut-red or Vandyke brown, excepting the hairy tail, which is
black above. The under parts, including the lower side of the tail, are
whitish varying to yellowish or even buff. The redder tint causes this
species frequently to be styled the Red Vole. It has pink lips, and grey
feet. Whiskers about an inch long. Black and albino varieties have been
recorded.
It was considered formerly to be a rare British species, but more
discriminating attention to the smaller mammals in recent years, and
the wider adoption of trapping by naturalists, have tended to modify
that view. It is probably more local, but it appears to be widely
distributed, and to occur as far north certainly as Moray and Elgin;
but it is not recorded from Ireland, Man, Hebrides, or Shetland. A local
race is found in Skomer Island, and has been named _E. skomerensis_.
When Yarrell detected the Bank Vole as a distinct species in 1832,
it was considered to be of very restricted range in this country.
The discovery was made in Essex, but it was soon reported from
Herefordshire, Middlesex, Berks, and Cambridge, and more recently
from Oxfordshire, Warwickshire, Shropshire, Worcestershire, the Lake
District, Northumberland, Inverness, etc. It is restricted to Europe
in its wider range. In this country it does not appear to occur at
elevations of more than about 700 feet.
The Bank Vole is much more agile than the Field Vole, and not so much
given to burrowing. It may be seen abroad in sunny situations at any
time of the day, preferring warm, dry places, yet frequently to be found
in wet places. It is a good swimmer and diver. It constructs shallow
runs in the earth of a roadside bank or hedgebank. These have many
entrances and exits above and below, as shown in our photograph; some
of the passages connecting with the top of the bank, others enlarging
into blind chambers. Its food includes herbage, roots, bulbs, fruits,
and seeds; it appears to be particularly fond of turnips. In spring it
has been observed climbing rose and hawthorn bushes in order to nibble
the new leaves, and in autumn to obtain the hips and haws. It also seeks
nuts, berries, the grain of wheat and barley, and the seeds of smaller
grasses. Insects, snails, and even small birds are eaten by it, and the
entrance to its burrows frequently gives evidence of the variety of its
food. It has been known to eat the unpalatable Shrew that it has killed,
and even to given way to cannibalism. In Scotland it is accused of
eating the shoot-buds of young conifers, especially of larch, and
gnawing the bark from branches.
In this country it is occasionally captured in the act of robbing
household stores, but in more northern regions, as in Norway and the
Yukon, it is a constant inhabitant of houses. It is not one of the
hibernating species, therefore as a rule it does not lay up stores;
but Mr. Douglas English records the digging up of five Bank Voles with
a store of ninety-three sound cob-nuts.
There are several litters of three to six naked and blind young during
the year, produced in nests of grass, moss and wool, or feathers,
usually placed above ground, sometimes in a bird's nest at some height
above it. The males are very quarrelsome, and when fighting or pairing
are very vocal, indulging in grunting squeaks.
* * * * *
Three geographical races or sub-species have been recognised by
Barrett-Hamilton as distinct species under distinct names. These are
Skomer Bank Vole (_Evotomys skomerensis_) from Skomer Island, off
Pembroke; Alston's Bank Vole (_E. alstoni_) from the Isle of Mull;
and the Raasay Bank Vole (_E. erica_) from Raasay Island, Skye.
Barrett-Hamilton regards these as descendants of a former "Boreal"
group of Voles, which have been supplanted on the British mainland by
the competition of the Bank Vole.
[Illustration: _Pl. 72._ _H 112._
*Retreat of the Bank Vole.*
Run continues from hole (left) under exposed root (right).]
[Illustration: _Pl. 73._ _H 113._
*Rabbit.*
Oryctolagus cuniculus.]
*Rabbit* (_Oryctolagus cuniculus_, Linn.).