he one day saw through a glass a herd of these animals which evidently
had been frightened, and were running away at full speed, although
their distance was so great that he could not distinguish them with
his naked eye. The sportsman frequently receives the first notice of
their presence, by hearing from a long distance their peculiar shrill
neighing note of alarm. If he then looks attentively, he will probably
see the herd standing in a line on the side of some distant hill. On
approaching nearer, a few more squeals are given, and off they set at
an apparently slow, but really quick canter, along some narrow beaten
track to a neighboring hill. If, however, by chance, he abruptly meets
a single animal, or several together, they will generally stand
motionless and intently gaze at him; then perhaps move on a few yards,
turn round, and look again. What is the cause of this difference in
their shyness? Do they mistake a man in the distance for their chief
enemy the puma? Or does curiosity overcome their timidity? That they
are curious is certain; for if a person lies on the ground, and plays
strange antics, such as throwing up his feet in the air, they will
almost always approach by degrees to reconnoitre him. It was an
artifice that was repeatedly practised by our sportsmen with success,
and it had moreover the advantage of allowing several shots to be
fired, which were all taken as parts of the performance. On the
mountains of the Tierra del Fuego, I have more than once seen a
guanaco, on being approached, not only neigh and squeal, but prance
and leap about in the most ridiculous manner, apparently in defiance
as a challenge. These animals are very easily domesticated, and I have
seen some thus kept in northern Patagonia near a house, though not
under any restraint. They are in this state very bold, and readily
attack a man by striking him from behind with both knees. It is
asserted that the motive for these attacks is jealousy on account of
their females. The wild guanacos, however, have no idea of defence;
even a single dog will secure one of these large animals, till the
huntsman can come up. In many of their habits they are like sheep in a
flock. Thus when they see men approaching in several directions on
horseback, they soon become bewildered, and know not which way to run.
This greatly facilitates the Indian method of hunting, for they are
thus easily driven to a central point, and are encompassed.
[Illustration: THE GUANACO.]
The guanacos readily take to the water: several times at Port Valdes
they were seen swimming from island to island. Byron, in his voyage, says
he saw them drinking salt water. Some of our officers likewise saw a
herd apparently drinking the briny fluid from a salina near Cape Blanco.
I imagine in several parts of the country, if they do not drink salt
water, they drink none at all. In the middle of the day they frequently
roll in the dust, in saucer-shaped hollows. The males fight together;
two one day passed quite close to me, squealing and trying to bite each
other; and several were shot with their hides deeply scarred. Herds
sometimes appear to set out on exploring parties; at Bahia Blanca,
where, within thirty miles of the coast, these animals are extremely
unfrequent, I one day saw the tracks of thirty or forty, which had come
in a direct line to a muddy salt-water creek. They then must have
perceived that they were approaching the sea, for they had wheeled with
the regularity of cavalry, and had returned back in as straight a line
as they had advanced. The guanacos have one singular habit, which is
to me quite inexplicable; namely, that on successive days they drop
their dung in the same defined heap. I saw one of these heaps which
was eight feet in diameter, and was composed of a large quantity. This
habit, according to M. A. d'Orbigny, is common to all the species of
the genus; it is very useful to the Peruvian Indians, who use the dung
for fuel, and are thus saved the trouble of collecting it.
The guanacos appear to have favorite spots for lying down to die. On
the banks of the St. Cruz, in certain circumscribed spaces, which were
generally bushy and all near the river, the ground was actually white
with bones. On one such spot I counted between ten and twenty heads. I
particularly examined the bones; they did not appear, as some
scattered ones which I have seen, gnawed or broken, as if dragged
together by beasts of prey. The animals in most cases must have
crawled, before dying, beneath and amongst the bushes. Mr. Byron
informs me that during a former voyage he observed the same
circumstances on the banks of the Rio Gallegos. I do not at all
understand the reason of this, but I may observe, that the wounded
guanacos at the St. Cruz invariably walked towards the river. At St.
Jago in the Cape de Verd islands, I remember having seen in a ravine a
retired corner covered with bones of the goat; we at the time
exclaimed that it was the burial-ground of all the goats in the
island.
BATS
(FROM STUDIES OF ANIMATED NATURE.)
BY W. S. DALLAS, F.L.S.
[Illustration: SLEEPING BAT.]
Among the sounds which greet the ear of the wayfarer as the shades of
evening deepen into night, one of the commonest is a rather faint
chirping noise which comes mysteriously from overhead. On looking up
in search of the source of this peculiar sound, we may see a small,
dark, shadow-like creature sweeping to and fro with great rapidity. It
is one of the curious groups of animals called Bats, representatives
of which are to be met with in in all countries, always active at
night or in the twilight, and presenting a remarkable general
similarity of structure, although in some respects they may differ
considerably in habits. In the British Islands some fourteen species
have been distinguished.
Like the owls, with which they share the dominion of the evening air,
the Bats have a perfectly noiseless flight; their activity is chiefly
during the twilight, although some species are later, and in fact seem
to keep up throughout the whole night. As they rest during the day,
concealed usually in the most inaccessible places they can find, and
are seen only upon the wing, their power of flight is their most
striking peculiarity in the popular mind, and it is perhaps no great
wonder that by many people, both in ancient and modern times they have
been regarded as birds. Nevertheless, their hairy bodies and leathery
wings are so unlike anything that we ordinarily understand as
pertaining to a bird, that opinion was apparently always divided, as
to the true nature of these creatures--"a mouse with wings," as
Goldsmith called it once, according to James Boswell, is certainly a
curious animal, and very difficult to classify so long as the would-be
systematist has no particularly definite ideas to guide him. The
likeness of the Bat to a winged mouse has made itself felt in the name
given to the creature in many languages, such as the "Chauvesouris" of
the French and the "Flitter-mouse" of some parts of England, the
latter being reproduced almost literally in German, Dutch, and
Swedish, while the Danes called the Bat a "Flogenmues," which has
about the same meaning, and the Swedes have a second name, "Laedermus,"
evidently referring to the texture of the wings, as well as to the
mouse-like character of the body.
But so soon as we have definite characters to appeal to in
classification, we find no difficulty in assigning these puzzling
creatures to their proper place in the system. Bats produce their
young alive, and suckle them; the milk being produced by special
glands. Now, these are characters which are peculiar among all animals
to the vertebrate class Mammalia. They possess also other characters
that are unmistakably mammalian. Leaving out of consideration the
structure of the internal organs, they have teeth implanted in sockets
in the jaws, four limbs, and a hairy covering to the skin, so that
they possess more decidedly mammalian characters than some other
members of the class, such as the marine whales and dolphins
(_Cetacea_) and manatees (_Sirenia_), which are still often spoken of
as fishes. In point of fact, although organized for flight, the Bat
may, without any violence to language, be spoken of as a _quadruped_,
for its fore-limbs contain all the parts found in those of other
mammals fully developed, and they come into use when the creature is
walking on the ground.
Perhaps the special characteristics of the Bats will be brought out
most distinctly by a comparison of their structure with that of a
bird, seeing that the modification of the fore-limbs into wings is
their most striking distinction from other Mammalia; for, although
some other members of the class are spoken of as "flying," such as the
Flying Squirrels, Flying Lemurs, and Flying Phalangers, these
creatures do not really fly, but merely glide through the air to
considerable distances by the action of a broad fold of skin which
runs down each side of the body, and which, when stretched between
the extended limbs, buoys the creatures up in the air after the
fashion of a parachute.
Most of us must have had occasion to pick the bones of a bird's wing,
a piece of practical anatomy which may serve us in good stead at
present. They consist of a long bone, which may be called the arm-bone
(_humerus_), jointed to the shoulder-bones (the so-called "side-bones"
of a fowl or turkey), followed by a pair of parallel bones
constituting the fore-arm, at the end of which we find two or three
small bones, then two parallel bones united at their extremities, and
some smaller joints terminating the whole.
We need say nothing about the arm-bone and the two bones of the
fore-arm, the peculiarity of bird-structure lying chiefly in the
terminal portion of the limb, or the hand. Here we find, after two
little bones forming the wrist, a pair of long bones as above
described, firmly united both at base and apex, and on the outside of
the base of these, close to the wrist, a small bone, which may be
either free or soldered to the others, and which represents the thumb
in the human hand. At the other end of the piece formed by the two
united bones, the limb is continued by two joints, forming a second
finger, inside of which there is usually a single small bone,
representing a third finger. But all these parts are stiffly attached
to one another, admitting of very little motion, so that the whole
hand forms as it were a single piece. The bony structure of the bird's
wing is in point of fact a rod hinged in two places, at the elbow and
the wrist, for the convenience of being folded into a small compass.
The flight of the bird is effected by the agency of a number of stiff
feathers implanted in the skin covering the bones and muscles of the
arm and hand; these fold together like the sticks of a fan when the
wing is folded, and are spread into an elastic instrument for striking
the air when the different sections of the bony framework are extended
by the action of their respective muscles.
In the Bat the structure is very different. Of course, as in the
Vertebrata generally, we find in the Bat's fore-limb the same three
main sections as in birds; and as the function of the limb is the
same, and a certain stiffness is necessary in the extended organ, the
movements of the joints at the elbow and wrists are hinge-like. But
the bones of the arm and fore-arm are longer and more slender,
especially the latter; and in this part, in place of the two parallel
bones of the bird's wing, we find in the Bat only a single long bone
representing the smaller bone of the bird, the larger one being
usually reduced to very small dimensions, and firmly united with the
other into a single piece, although it still forms the elbow-joint. At
the other end of this long fore-arm we find some small wrist-bones and
to these the fingers are articulated. In birds, as we have seen, only
two or three fingers are represented, and these are more or less
reduced in size, and the most important of them soldered together;
Bats, on the contrary, show the whole five fingers as distinctly as in
the hand of man or any other mammals. The first of them, or the
_thumb_, is short, slender, and flexible, and composed of three
joints; the other four are very long and slender, but chiefly
composed of the metacarpal bones, corresponding to those of the palm
of the human hand. The first, or index finger, indeed, in many Bats,
consists of this bone alone; but in the others it is followed by two
or three slender joints, gradually tapering to the extremity, the
second finger, corresponding to our middle finger, being always the
longest of all.
Just as is the bird's wing, these various parts can be folded together
or extended by the action of the muscles, but in the Bat the long
fingers become separated when the wing is stretched out, and by this
action they at the same time stretch a thin leathery double membrane
in which they are enclosed, which is thus converted into a broad
surface for striking the air in flight. This membrane is continued
from the fingers to the sides of the body, and even to the hind limbs,
which are often included in it to the ankle-joints; while in the great
majority of Bats there is even a further portion of membrane between
the hind legs, enclosing the whole or a portion of the tail. There is
usually also a narrow strip of the same membrane in front of each arm,
so that the skin of the animal is extended as much as possible, in
order to give it support in its aerial evolution. It is to be noted
that the long second finger extends to the extreme point of the wing
and that the first finger runs close beside it and thus assists in
stiffening that part of the organ. The thumb is left free, and is
furnished with a rather strong hooked claw.
Supported by the action of these great leathery wings, the Bat flies
about almost incessantly during the twilight, and often late into the
night. In full career its flight is swift, though perfectly
noiseless, and it has the power of executing rapid turns and changes
of direction with the greatest facility, as required for the capture
of its prey, which, in the great majority of cases, consists of the
insects of various kinds that in most places fly by night. In pursuit
of these, the Bats flit rapidly about trees, houses, and other
buildings, now and then resting by clinging for a moment to the rough
surfaces of the walls or the trunks and branches of trees. Old country
church-yards, which are usually full of trees, are naturally favorite
haunts of these nocturnal insect-hunters, offering them an excellent
field for the chase of their prey, while at the same time, the church
itself, with its architectural peculiarities, usually affords them a
safe retirement during the day in the dark and secluded corners of its
structure. Hence in the popular mind the Bat has long been associated
with the church-yard, that spot so dreaded that few can pass through
it after nightfall without experiencing certain peculiar feelings, so
that it is no great wonder if a portion of the superstitious fear thus
engendered has transferred itself to these frail and harmless
creatures, and given them and their companions, the owls, something of
an evil reputation. And it must be confessed that when seen against
the light, flitting silently overhead, there is something weird in the
Bat's form, and this is no doubt the reason why, while angels of all
kinds are represented with birds' wings, those of Bats have, by
universal consent, always been conferred upon demons, dragons, and
similar uncanny creatures.
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 aerial 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 manoeuvre
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.
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.