THE BATS
Next in order to the monkeys come the bats, the only mammals which are
able to fly. It is quite true that there are animals known as flying
squirrels, which are sometimes thought to have the power of flight. But
all that these can do, as we shall see by and by, is to take very long
leaps through the air, aided by the curious manner in which the loose
skin of the body is fastened to the inner surface of the legs.
HOW BATS FLY
Bats, however, really can fly, and the way in which their wings are made
is very curious. If you were to look at a bat's skeleton, you would
notice, first of all, that the front limbs were very much larger than
the hinder ones. The upper arm-bone is very long indeed, the lower
arm-bone is longer still, and the bones of the fingers are longest of
all. The middle finger of a bat, indeed, is often longer than the whole
of its body! Now these bones form the framework of the wing. You know
how the silk or satin of a lady's fan is stretched upon the ribs. Well,
a very thin and delicate skin is stretched upon the bones of a bat's arm
and hand in just the same way. And when the little animal wants to fly,
it stretches its fingers apart, and so spreads the wing. When it wants
to rest it closes them, and so folds it against its body.
Then you would notice that a high bony ridge runs down the bat's
breast-bone. Now such a ridge as this always signifies great strength,
because muscles must be fastened at each end to bones; and when the
muscles are very large and powerful, the bones must be very strong in
order to carry them. So, when an animal needs very strong
breast-muscles, so that it may be able to fly well, we always find a
high bony ridge running down its breast-bone; and to this ridge
the great muscles which work the wings are fastened.
Something more is necessary, however, if the animal is to fly properly.
It must be able to steer itself in the air just as a boat has to be
steered in the water. Otherwise it would never be able to fly in the
right direction. So nature has given it a kind of air-rudder; for the
skin which is stretched upon the wings is carried on round the end of
the body, and is supported there, partly by the hind legs, and partly by
the bones of the tail. And by turning this curious rudder to one side or
the other, or tilting it just a little up or a little down, the bat is
able to alter its course at will.
THE USEFUL CLAW
But you would notice something else on looking at a bat's skeleton. You
would notice that the bones of the thumb are not long and slender, like
those of the fingers, but that they are quite short and stout, with a
sharp hooked claw at the tip. The bat uses this claw when it finds
itself on the ground. It cannot walk, of course, as it has no front
feet; so it hitches itself along by means of its thumbs, hooking first
one claw into the ground and then the other, and so managing to drag
itself slowly and awkwardly forward.
It is not at all fond of shuffling along in this way, however, and
always takes to flight as soon as it possibly can. But as it cannot well
rise from the ground it has to climb to a little height and let itself
drop, so that as it falls it may spread its wings and fly away. And it
always climbs in a very curious manner, with its tail upward and its
head toward the ground, using first the claws of one little foot and
then those of the other.
When a bat goes to sleep it always hangs itself up by the claws of its
hind feet. In an old church tower, or a stable loft, you may often find
bats suspended in this singular way. And there is a reason for it. The
bat wants to be able, at the first sign of danger, to fly away. Now if
it lay flat upon the ground to sleep, as most animals do, it would not
be able to fly quickly; for it would have to clamber up a wall or a post
to some little height before it could spread its wings. And this
would take time. But if it should be alarmed while it is hanging by its
hind feet, all that it has to do is to drop into the air and fly off at
once.
BATS IN THE DARK
There is something else, too, that we must tell you about bats. They
have the most wonderful power of flying about on the darkest night,
without ever knocking up against the branches of trees, or any other
obstacles which they may meet on their way. It used to be thought that
this was because they had very keen eyes. But it has been found out that
even a blind bat has this power, which seems really to be due to very
sensitive nerves in the wings. You can feel a branch by touching it. But
a bat is able to feel a branch _without_ touching it, while it is
eight or ten inches away, and so has time to swerve to one side without
striking against it.
THE WINTER SLEEP
Bats, like hedgehogs and squirrels, pass through the winter in a kind of
deep sleep, which we call hibernation. It is more than ordinary sleep,
for they do not require any food for months together, while they
scarcely breathe once in twenty-four hours, and their hearts almost
cease to beat. If the winter is cold throughout, they do not wake at all
until the spring. But two or three hours' warm sunshine arouses them
from their slumber. They wake up, feel hungry, go out to look for a
little food, and then return to their retreats and pass into the same
strange sleep again.
AN INTERESTING SPECIMEN
"I once kept a long-eared bat as a pet," says a writer, "and a most
interesting little creature he was. One of his wings had been injured by
the person who caught him, so that he could not fly, and was obliged to
live on the floor of his cage. Yet, although he could take no
exercise, he used to eat no less than seventy large bluebottle flies
every evening. As long as the daylight lasted, he would take no notice
of the flies at all. They might crawl about all over him, but still he
would never move. But soon after sunset, when the flies began to get
sleepy, the bat would wake up. Fixing his eyes on the nearest fly, he
would begin to creep toward it so slowly that it was almost impossible
to see that he was moving. By degrees he would get within a few inches.
Then, quite suddenly, he would leap upon it, and cover it with his
wings, pressing them down on either side of his body so as to form a
kind of tent. Next he would tuck down his head, catch the fly in his
mouth, and crunch it up. And finally he would creep on toward another
victim, always leaving the legs and the wings behind him, which in some
strange way he had managed to strip off, just as we strip the legs from
shrimps.
"I often watched him, too, when he was drinking. As he was so crippled,
I used to pour a few drops of water on the floor of his cage, and when
he felt thirsty he would scoop up a little in his lower jaw, and then
throw his head back in order to let it run down his throat. But in a
state of freedom bats drink by just dipping the lower jaw into the water
as they skim along close to the surface of a pond or a stream, and you
may often see them doing so on a warm summer's evening."
THE PIPISTRELLE
The pipistrelle, a common European bat, is said to feed chiefly upon
gnats, of which it must devour a very large number, and as it much
prefers to live near human habitations, there can be no doubt that it
helps to keep houses free from these disagreeable insects. In captivity
it will feed freely upon raw meat chopped very small. It appears earlier
in the spring than the other bats, and remains later in the autumn.
HORSESHOE BATS
These bats of the Old World have a most curious leaf-like membrane upon
the face, which gives them a very odd appearance. In the great
horseshoe bat this membrane is double, like one leaf placed above
another. The lower one springs from just below the nostrils, and spreads
outward and upward on either side, so that it is shaped very much like a
horseshoe, while the upper one is pointed and stands upright, so as
partly to cover the forehead. The ears, too, are very large, and are
ribbed crosswise from the base to the tips; so that altogether this bat
is a strange-looking creature.
Perhaps none of the bats is more seldom seen than this, for it cannot
bear the light at all, and never comes out from its retreat until
darkness has quite set in. And one very seldom finds it asleep during
the day, for it almost always hides in dark and gloomy caverns, which
are hardly ever entered by any human being. In France, however, there
are certain caves in which great numbers of these bats congregate
together for their long winter sleep. As many as a hundred and eighty of
them have been counted in a single colony. And it is a very strange fact
that all the male bats seem to assemble in one colony, and all the
female bats in another.
VAMPIRES
In Central and South America, and also in the West Indian Islands, a
number of bats are found which are known as vampires. Some of these eat
insects, just like the bats of other countries, and one of them--known
as the long-tongued vampire--has a most singular tongue, both very long
and very slender, with a brush-like tip, so that it can be used for
licking out insects from the flowers in which they are hiding. Then
there are other vampires which eat fruit, like the flying foxes, about
which we shall have something to tell you soon. But the best known of
these bats, and certainly the strangest, are those which feed upon the
blood of living animals.
If you were to tether a horse in those parts of the forest where these
vampires live, and to pay it a visit just as the evening twilight was
fading into darkness, you would be likely to see a shadowy form hovering
over its shoulders, or perhaps even clinging to its body. This would be
a vampire bat; and when you came to examine the horse, you would
find that, just where you had seen the bat, its skin would be stained
with blood. For this bat has the singular power of making a wound in the
skin of an animal, and sucking its blood, without either alarming it or
appearing to cause it any pain. And if a traveler in the forest happens
to lie asleep in his hammock with his feet uncovered, he is very likely
to find in the morning that his great toe has been bitten by one of
these bats, and that he has lost a considerable quantity of blood. Yet
the bat never wakes him as it scrapes away the skin with its sharp-edged
front teeth.
Strangely enough, however, there are many persons whom vampires will
never bite. They may sleep night after night in the open, and leave
their feet entirely uncovered, and yet the bats will always pass them
by. Charles Waterton, a famous English traveler, was most anxious to be
bitten by a vampire, so that he might learn by his own experience
whether the infliction of the wound caused any pain. But though he slept
for eleven months in an open loft, through which the bats were
constantly passing, they never attempted to touch him, while an Indian
lad who slept in the same loft was bitten again and again.
But as these bats cannot always obtain blood, it is most likely that
they do not really live upon it, but only drink it when they have the
chance, and that as a rule their food consists of insects.
FLYING FOXES
Of course these are not really foxes. They are just big bats which feed
on fruit, instead of on insects or on blood. They are called also
fruit-bats. But their long, narrow faces are so curiously fox-like that
we cannot feel surprised that the name of flying foxes should have been
given to them.
Flying foxes are found in many parts of Asia, as well as in Madagascar
and in Australia, and in some places they are very common. In India,
long strings of these bats may be seen regularly every evening, as they
fly off from their sleeping-places to the orchards in search of fruit.
In some parts of India, early in the morning, and again in the evening,
the sky is often black with them as far as the eye can reach, and they
continue to pass overhead in an unbroken stream for nearly
three-quarters of an hour. And as they roost in great numbers on the
branches of tall trees, every bat being suspended by its hinder feet,
with its wings wrapped round his body, they look from a little distance
just like bunches of fruit.
It is rather curious to find that when they are returning to the trees
in which they roost, early in the morning, these bats quarrel and fight
for the best places, just as birds do.
In districts where they are at all plentiful, flying foxes do a great
deal of mischief, for it is almost impossible to protect the orchards
from their attacks. Even if the trees are covered all over with netting
they will creep underneath it, and pick out all the best and ripest of
the fruit; while, as they only pay their visits of destruction under
cover of darkness, it is impossible to lie in wait for them and shoot
them as they come.
The flight of the fruit-bats is not at all like that of the bats with
which we are familiar, for as they do not feed upon insects there is no
need for them to be constantly changing their course, and darting first
to one side and then to the other in search of victims. So they fly
slowly and steadily on, following one another just as crows do, and
never turning from their course until they reach their feeding-ground.
The largest of these fruit-bats is the kalong, which is found in the
islands of the Malay Archipelago. It measures over five feet from tip to
tip of the extended wings. The Malays often use it for food, and its
flesh is said to be delicate and well flavored.