tropical bats.
wonderful organisation of the bats—the fox-bat—the vampire—its blood-sucking propensities—the horse-shoe bats—the flying squirrel—the galeopithecus—the anomalurus.
when the sun has disappeared below the horizon, and night falls on the landscape, which a little while ago was bathed in light, then from hollow trees, and creviced rocks, and ruined buildings, a strange and dismal race comes forth.
silently hovering through the glades of the wood, or skimming along the surface of the streams, it catches the crepuscular or nocturnal moths, and serves like the swallow by day to check the exuberant multiplication of the insect tribes. but while man loves the swallow, and suffers him to build his nest under the eaves of his dwelling, he abhors the bat, which like an evil spirit avoids the light of day, and seems to feel happy only in darkness. the painter, expressing this general feeling, gives491 to his angels the white pinions of the swan, while his demons are made to bear the black wings of the bat. and yet the bat, in europe at least, is a most inoffensive creature, which may well claim the gratitude of the farmer, from the vast numbers of cockchafers and other noxious insects which it destroys; while a closer inspection of its wonderful organisation proves it to be far more deserving of admiration than of repugnance. can anything be better adapted to its wants than the delicate membrane which, extending over the long slim fingers, can be spread and folded like an umbrella, so as to form a wing when the animal wishes to fly, and to collapse into a small space when it is at rest? how slight the bones, how light the body, how beautifully formed for flight!
though temperate europe possesses many bats, yet they are most numerous and various in the woody regions of the tropical zone, where the vast numbers of the insect tribes and forest fruits afford them a never-failing supply of food. there also they attain a size unknown in our latitudes, so that both from their dimensions and their physiognomy, many of the larger species have obtained the name of flying-dogs or flying-foxes.
on approaching a javanese village, you will sometimes see a stately tree, from whose branches hundreds of large black fruits seem to be suspended. a strong smell of ammonia and a piping noise soon, however, convince you of your mistake, and a closer inspection proves them to be a large troop of kalongs, or flying-foxes (pteropus), attached head downwards to the tree, where they rest or sleep during the daytime, and which they generally quit at sunset, though some of them differ so much from the usual habits of the family as to fly about in the broad light of day.
many species of fox-bats are found all over the torrid zone in the old world, but they abound particularly in the east indian archipelago. they belong to the rare quadrupeds indigenous in some of the south sea islands, such as tonga or samoa, and extend northwards as far as japan, and southwards to van diemen’s land. they occasion incalculable mischief in the plantations, devouring indiscriminately every kind of fruit; but, on the other hand, the gigantic kalong of java (pteropus edulis), whose body attains a length of a foot and a half, and whose outstretched wings measure no less than four492 feet and a half from tip to tip, is eaten as a delicacy by the natives.
the same essential differences which we observe between the monkeys of both hemispheres, are also found to exist between the large bats of the old and the new world. not a single fox-bat is to be found in all america, while the phyllostomidæ, distinguished by the orifices of their nostrils being placed in a kind of membranous scutcheon, surmounted by a leaf-like expansion, like the head of a lance, and supposed to extend in an extraordinary degree the sense of smelling, are exclusively confined to the western continent. these large bats of which there are many species, some measuring above two feet from wing to wing, are remarkable for their blood-sucking propensities, and under the name of vampires have brought the whole race of the large tropical bats into evil repute.
the phyllostomahastatum, a common species on the amazons, chiefly feeds on vespertine and nocturnal moths, but does also much injury to horses and cattle, and even attacks man when it has an opportunity. the prince of neu wied often saw it by moonlight hovering about his horses while grazing after their day’s journey. the animals did not seem incommoded by its attacks, but on the following morning he generally found them covered with blood from the shoulders to the hoofs. there is still some uncertainty as to the way in which it inflicts its wound, which is a small round hole, the bleeding of which it is very difficult to stop. it can hardly be a bite, as that would awake the sleeper; it seems most probable that it is either a succession of gentle scratches with the sharp edge of the teeth, gradually wearing away the skin, or a triturating with the point of the tongue till the same effect is produced. after the wound is made the muscular underlip of the vampire, which can be completely folded together in the shape of a sucking-tube, continues to pump forth the blood, the wings of the bat serving at the same time to fan the patient into a deeper slumber.
many persons are particularly annoyed by the phyllostoma, while others are free from their attacks. mr. wallace, who was himself twice bitten, once on the top of the great toe, the usual locality, and the other time on the top of the nose, mentions an old mulatto on the upper rio negro, who was attacked493 almost every night, and though there were frequently half a dozen other persons in the room, would be the favoured party. an indian girl at manaquery, on the upper amazon, who was likewise frequently annoyed by the bats, was at length so much weakened by loss of blood, that fears were entertained of her life if they continued their attacks, and it was found necessary to send her to a distance, where her bloodthirsty persecutors did not abound.
in the province of minas geraes innumerable troops of large bats issue from the limestone caverns on the banks of the rio francisco, or from the crevices of the granite walls of the parime mountains, and not seldom attack the cattle with such bloodthirsty obstinacy as to oblige the planters to drive their herds to some other part of the country. to keep them in check, tobacco and sulphur are from time to time ignited under the rocks where they abound, when the stunned bats drop down, and are killed by thousands.
the vampires may sometimes be seen in the forest, hanging in clusters, head downwards, from the branch of a tree, a circumstance of which goldsmith seems to have been aware, for in the ‘deserted village,’ speaking of america, he says—
‘and matted woods, where birds forget to sing, but silent bats in drowsy clusters cling.’
some of the phyllostomidæ have a tongue once as long again as the head, and armed at the extremity with recurved bristles, like that of the woodpecker, no doubt a very serviceable instrument for extracting insects from the narrow hollows and crevices of trees and rocks.
rhinolophus.
the rhinolophi, or horse-shoe bats, of the old continent, have also a more or less complicated nasal appendage, or foliaceous membrane at the end of the nose but differing in its conformation from that of the phyllostomidæ.494 they are insectivorous, like most of their order, and none of them seem to indulge in the blood-sucking propensities of the large american vampires. they chiefly inhabit the tropical regions of africa and asia, and more particularly the indian archipelago, but the rhinolophus unihastatus ranges in europe as far as england.
numerous genera and species of tropical bats, distinguished from each other by the formation of their teeth, lips, nostrils, heads, wings, and tails, have already been classified by naturalists, but many, no doubt, still live unknown in their gloomy retreats, for who is able to follow them into the obscure nooks of the forest, or into intricate caverns, and accurately to observe them during their nocturnal rambles? it may give an idea of their vast numbers throughout the torrid zone, when we hear that in ceylon alone about sixteen species have been identified, and of these, two varieties are peculiar to the island. unlike the sombre bats of the northern climates, the colours of some of them are as brilliant as the plumage of a bird, bright yellow, deep orange, or of a rich ferruginous brown, thus contradicting the general belief which attires nocturnal animals in vestures as dark as their pursuits.
the torrid zone, which produces the largest bats, also gives birth to the tiniest representatives of the order, such as the minute singhalese variety of scotophilus coromandelicus, which is not much larger than the humble bee, and of a glossy black colour. ‘it is so familiar and gentle,’ says sir j. e. tennent, ‘that it will alight on the cloth during dinner, and manifests so little alarm that it seldom makes any effort to escape before a wine-glass can be inverted to secure it.’
though incapable of a prolonged flight like the bats, several other tropical quadrupeds have been provided with extensions of the skin, which give them the power of supporting themselves for some time in the air, and of making prodigious leaps. thus, by means of an expansile furry membrane, reaching from the fore-feet to the hind, the flying squirrels (pteromys) bound, or rather swiftly sail, to the distance of twenty fathoms or more, and thus pass from one tree to another, always directing their flight obliquely downwards. they very rarely descend to the ground, and when taken or placed on it, run or spring somewhat awkwardly with their tail elevated,495 beginning to climb with great activity as soon as they reach a tree.
the galeopitheci, of the indian archipelago, and the anomaluri of the west coast of africa, are in like manner enabled to take long sweeping leaps from tree to tree, and no doubt the investigations of travellers will bring to light other animals endowed with similar powers, for when we consider how large a portion of the tropical zone has never yet been scientifically investigated, we have every reason to believe that many still remain unknown.
