CHAPTER IV

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.