When it descends from its flight upon the ground or any solid body, the Bat becomes to all intents and purposes a genuine quadruped. The fingers being drawn together, with the membranes of the wings thrown into folds between them, the whole hand of the creature is brought up parallel to the fore-arm, and so got out of the way, and the animal can then walk more or less easily, its hind legs, though short and rather feeble, being perfectly formed, and the fore limbs, from which the thumbs with their sharp claws now project freely, becoming available for terrestrial progression. Nevertheless, this progression is generally rather clumsy, as indeed might be expected from creatures so curiously constructed.
While on the wing, our Bats are constantly engaged in the pursuit of the numerous insects of various kinds which, like themselves, are active in the evening and after dark, and of these they must destroy immense quantities. The swarms of delicate gnats and midges which disport themselves in the most complicated aërial dances, moths of all kinds, and even the hard-shelled beetles, many of which fly about in the evening or at night, fall a prey to these leathern-winged rovers of the night air, and weak as the latter would seem to be, some of them are able to seize and devour beetles which appear to be far beyond their powers. Thus, the largest of our British species, the Great Bat, or Noctule (Scotophilus noctula), which, however, is only about three inches in length, preys freely upon such large and hard-shelled insects as cockchafers; these, in fact, appear to be its favorite food, and for their consumption its broad and comparatively strong jaws would seem to be specially fitted, while its large and powerful wings, measuring fourteen or fifteen inches from tip to tip when expanded, enable it to fly with the rapidity necessary for the pursuit and capture of such powerful prey. When thus engaged, the Noctule haunts the neighborhood of trees, and generally flies at a considerable elevation, from which, however, his shrill cry easily reaches the ear of the passer-by. His addiction to large prey gives rise to a curious movement, thus noticed by Professor Bell in his valuable book on “British Quadrupeds.” “An observer will not watch his movements long,” says the Professor, “without noticing a manœuvre which at first looks—like the falling of a tumbler-pigeon, but on closer examination proves to be simply a closing of the wings, and a consequent drop of about a foot. Sometimes, this is repeated every few yards, as long as in sight. It is occasioned by some large and intractable insect having been captured, and the anterior joint of the wing, with its well-armed thumb, is required in retaining it until masticated.” Notwithstanding this little difficulty, however, the Noctule is pretty rapid in disposing even of his most recusant prey, as he has been known to consume as many as thirteen cockchafers one after another.
The foregoing statements apply to all our British Bats, and indeed, in the matter of food and general habits, to the great majority of the species of the order, in whatever country they may occur. But in the tropical and sub-tropical regions of the eastern hemisphere, we find a great and important group of Bats, which, although agreeing in general structure and habits with our European species, differ from them altogether in their diet. These Bats, distinguished generally, among other things, by their larger size and more robust construction, and by certain characters of the molar teeth (grinders), from the ordinary Bats, are almost exclusively confined to a fruit diet, in search of which they fly vigorously, often in flocks, like birds, at the commencement of the night. From this peculiarity of their food they are commonly known as Fruit Bats, while the larger species, such as the Indian Fruit Bat and the Kalong of the Eastern Archipelago, which are respectively eleven and fourteen inches in length, are sometimes called Flying Foxes, in allusion to the prevalence of a reddish tint in their fur, and their more or less lengthened and dog-like muzzles. In many parts of the Eastern world, in India, the Malayan Archipelago, Australia, Africa, and even in outlying islands at some distance from their main range, these Fruit Bats occur in great numbers. Swarms of them roost together during the day, hanging from the branches of the trees which they select as their regular resting-place, and taking wing at sunset, fly off frequently to great distances in search of their favorite articles of food; for they by no means devour indiscriminately any kind of fruit, but show a distinct preference for particular sorts, generally selecting such as are also prized by their human competitors. Hence they often do considerable damage in plantations of fruit trees, as when they meet with articles that suit taste, they seem, like some human gourmands, not to know when to leave off eating. Of one of the smaller Indian species, the Margined Fruit Bat, Mr. Dobson obtained a living specimen in Calcutta, and he gives the following account of its voracious appetite:—He gave it “a ripe banana, which, with the skin removed, weighed exactly two ounces. The animal immediately, as if famished with hunger, fell upon the fruit, seized it between the thumbs and the index fingers, and took large mouthfuls out of it, opening the mouth to the fullest extent with extreme voracity. In the space of three hours the whole fruit was consumed. Next morning the Bat was killed, and found to weigh one ounce, half the weight of the food eaten in three hours! Indeed, the animal when eating seemed to be a kind of living mill”—so continuously does its food pass through it.
The Vampire Bat.
From the statements of some writers, it would appear that although these Bats live chiefly upon fruits, they occasionally, like many other frugivorous animals, diversify their diet with animal food, devouring insects of various kinds, caterpillars, birds’ eggs, and even young birds, while there seems to be some reason to believe that one species even feeds upon shell-fish which it picks up upon the seashore.
The fruit-eating Bats of this group are not found in the warmer parts of America, but some American Bats feed chiefly upon fruits, while many of the large essentially insectivorous species which occur there vary their diet more or less with fruits, and also occasionally attack and devour other vertebrate animals. Some of them—but it is still very doubtful how many—have another habit connected with their feeding, which renders them very decidedly objectionable, namely, that of inflicting wounds upon birds and mammals, even including man himself, and sucking up the blood that flows from them. This charge has been brought against many Bats of South and Central America, some of which have been commonly named Vampires in consequence, after the ghostly blood-suckers, which were formerly the objects of so much superstitious terror in Hungary and other parts of Eastern Europe; but so far as can be made out from a consideration of the evidence, a verdict of “not proven,” at all events, must be arrived at in the case of all but two species, which constitute a little group distinguished by what is apparently a special organization adapting them to this peculiar diet. These wretched little beasts, which only measure two and a half or three inches in length, are furnished in the upper jaw with a single pair of incisor or front teeth, but these are of great size and strength, triangular in form, and so excessively sharp that when the creatures are seized they can draw blood from the hand of their captor by what seems a mere touch. This extreme sharpness of their weapons enables them, when attacking sleeping men or animals, to slice off a small portion of skin almost without causing any pain, and the little oval wounds thus produced, like the similar surface-cuts which a careless shaver sometimes inflicts upon his chin, bleed with particular freedom. The Desmodonts, as these true Vampires are called, will attack horses, mules, and cattle, which they generally wound on the back, near the spine, often in the region of the withers; and they also bite the combs of domestic fowls, and any part of the human body that they can get at. In the case of man, however, according to most authorities, the extremity of the great toe is the favorite part; and some writers, perhaps possessed of a strong poetical vein, have given wonderful descriptions of the artfulness with which these little blood-suckers make their approaches, and keep their victim comfortably asleep during the operation by fanning him with their wings. In fact, the Vampire Bats had so bad a reputation from the accounts given by travellers, that they seemed to be veritable scourges of the countries in which they live, but so far as can be made out from the most trustworthy reports, the mischief they cause may be summed up under two heads, namely, weakness produced by loss of blood, which continues to flow from the wounds long after the Bats have drunk their fill and gone quietly home to rest, and inflammatory affections, caused either by the irritation of the bite in the case of people of a bad habit of body, or by the friction of the saddle or collar upon the part bitten in the case of horses and mules, or of the shoe in the human patient. That the Desmodonts do really feed on blood is proved by evidence of various kinds. They have been captured in the act of blood-sucking, when their stomachs, which are peculiarly constructed and very long, are found filled with a black paste, which is evidently half-digested blood; and their teeth, which are in part so well adapted for producing the necessary wounds in other animals, are totally unfit for the mastication of an insect prey, such as constitutes the diet of their nearest allies.
After all this feeding, Bats, whatever the nature of their diet, not unnaturally find themselves inclined for repose, and as they are active during the night or in the twilight, of course their rest has to be taken in the daytime. To pass the period of repose in security they seek shelter of various kinds, not only for protection against the weather, but also for the sake of concealment from other predaceous animals, some of which would no doubt be perfectly willing to make a meal of them. The great Eastern Fruit Bats, trusting perhaps to their size and strength, are content to resort to the branches of trees, from which, after the manner of Bats in general, they suspend themselves by the hind feet with the head downwards. From the statements of various writers it appears that after being out all night in search of food, the Flying Foxes and other allied Bats fly back to their regular resting-places, where they begin to arrive about or soon after dawn. The number resorting to the same retreat is usually so great that the whole of the branches are loaded with them, and in fact they are so crowded together that the settling down of the flock into their repose is preceded by a scene of squabbling and quarrelling of the most noisy description. Mr. Tickell, speaking of the common Indian Flying Fox, says:—“From the arrival of the first comer, until the sun is high above the horizon, a scene of incessant wrangling and contention is enacted among them, as each endeavors to secure a higher and better place, or to eject a neighbor from too close vicinage. In these struggles the Bats hook themselves along the branches, scrambling about hand over hand with some speed, biting each other severely, striking out with the long claw of the thumb, shrieking and cackling without intermission. Each new arrival is compelled to fly several times round the tree, being threatened from all points; and when he eventually hooks on, he has to go through a series of combats, and be probably ejected two or three times, before he makes good his tenure.” This scene of selfish contention over, the Fruit Bats pass some hours in profound sleep, during which they remain suspended in rows along the branches, to which they cling by one foot only, the other with all the lower surface of the body being comfortably wrapped in the leathery mantle formed by the contracted wings. In this condition, as Dr. Horsfield says of the Great Kalong, “ranged in succession with the head downwards ... and often in close contact, they have little resemblance to living beings, and by a person not accustomed to their economy are easily mistaken for a part of the tree, or for a fruit of uncommon size suspended from its branches.” In this position the head is folded down upon the breast. Dr. Bennett and Mr. Gould ascribed very similar habits to a large Fruit Bat common in the northern parts of New South Wales and in Queensland, which is said to be often exceedingly destructive to the peach and other fruit crops of the settlers in those colonies.
The European Bats, and indeed all the Bats except these Flying Foxes and their immediate allies, seek a different kind of shelter. Their chief natural dormitories consist of hollow trees and the caves and fissures of rocks, to which they often resort in great numbers; but in populous countries they also find an abundance of convenient places of retirement in and about buildings of various kinds. Roofs, especially when covered with tiles, or otherwise provided with apertures through which the space immediately under the roofing is easily accessible, outbuildings of all kinds, church towers and other similar structures, disused chimneys, the spaces behind weather-boards and shutters which are not often moved, in fact any dark and sheltered places about our buildings, are readily resorted to by many species, although some few retain their taste for unadulterated nature so strongly that no artificial harbor will serve their turn. Thus among the British species the Great Bat or Noctule, a generally distributed though not abundant species throughout the southern and middle counties of England, seems generally to retreat for its diurnal sleep to the holes or cavities in the trunks of trees, and only to visit buildings when there is a scarcity of such accommodation; and the Horseshoe Bats show a decided preference for caverns and deserted quarries; but the great majority appear to be indifferent in the matter, and to resort to any shelter that seems convenient to them. Some, such as the Barbastelle of the southern parts of England, are solitary in their habits, generally retiring alone for their day’s rest; others are more sociable, reposing in larger or smaller parties in their dormitories, whether natural or artificial, and sometimes, like the Fruit Bats, collecting in immense numbers.