The Naturalist in La Plata by W. H. Hudson (page 2)

beautiful in colour, is in form hideous beyond description. The skin is of a rich brilliant green, with chocolate-coloured patches, oval in form, and symmetrically disposed. The lips are bright yellow, the cavernous mouth pale flesh colour, the throat and under-surface dull white. The body is lumpy, and about the size of a large man’s fist. The eyes, placed on the summit of a disproportionately large head, are embedded in horn-like protuberances, capable of being elevated or depressed at pleasure. When the creature is undisturbed, the eyes, which are of a pale gold colour, look out as from a couple of watch towers, but when touched on the head or menaced, the prominences sink down to a level with the head, closing the eyes completely, and giving the creature the appearance of being eyeless. The upper jaw is armed with minute teeth, and there are two teeth in the centre of the lower jaw, the remaining portions of the jaw being armed with two exceedingly sharp-edged bony plates. In place of a tongue, it has a round muscular process with a rough flat disc the size of a halfpenny.

It is common all over the pampas, ranging as far south as the Rio Colorado in Patagonia. In the breeding season it congregates in pools, and one is then struck by their extraordinary vocal powers, which they exercise by night. The performance in no way resembles the series of percussive sounds uttered by most batrachians. The notes it utters are long, as of a wind instrument, not unmelodious, and so powerful as to make themselves heard distinctly a mile off on still evenings. After the amorous period these toads retire to moist places and sit inactive, buried just deep enough to leave the broad green back on a level with the surface, and it is then very difficult to detect them. In this position they wait for their prey–frogs, toads, birds, and small mammals. Often they capture and attempt to swallow things too large for them, a mistake often made by snakes. In very wet springs they sometimes come about houses and lie in wait for chickens and ducklings. In disposition they are most truculent, savagely biting at anything that comes near them; and when they bite they hang on with the tenacity of a bulldog, poisoning the blood with their glandular secretions. When teased, the creature swells itself out to such an extent one almost expects to see him burst; he follows his tormentors about with slow awkward leaps, his vast mouth wide open, and uttering an incessant harsh croaking sound. A gaucho I knew was once bitten by one. He sat down on the grass, and, dropping his hand at his side, had it seized, and only freed himself by using his hunting knife to force the creature’s mouth open. He washed and bandaged the wound, and no bad result followed; but when the toad cannot be shaken off, then the result is different. One summer two horses were found dead on the plain near my home. One, while lying down, had been seized by a fold in the skin near the belly; the other had been grasped by the nose while cropping grass. In both instances the vicious toad was found dead, with jaws tightly closed, still hanging to the dead horse. Perhaps they are sometimes incapable of letting go at will, and like honey bees, destroy themselves in these savage attacks.

CHAPTER V.

FEAR IN BIRDS.

The statement that birds instinctively fear man is frequently met with in zoological works written since the _Origin of Species_ appeared; but almost the only reason–absolutely the only plausible reason, all the rest being mere supposition–given in support of such a notion is that birds in desert islands show at first no fear of man, but afterwards, finding him a dangerous neighbour, they become wild; and their young also grow up wild. It is thus assumed that the habit acquired by the former has become hereditary in the latter–or, at all events, that in time it becomes hereditary. Instincts, which are few in number in any species, and practically endure for ever, are not, presumably, acquired with such extraordinary facility.

Birds become shy where persecuted, and the young, even when not disturbed, learn a shy habit from the parents, and from other adults they associate with. I have found small birds shyer in desert places, where the human form was altogether strange to them, than in thickly-settled districts. Large birds are actually shyer than the small ones, although, to the civilized or shooting man they seem astonishingly tame where they have never been fired at. I have frequently walked quite openly to within twenty-five or thirty yards of a flock of flamingoes without alarming them. This, however, was when they were in the water, or on the opposite side of a stream. Having no experience of guns, they fancied themselves secure as long as a strip of water separated them from the approaching object. When standing on dry land they would not allow so near an approach. Sparrows in England aro very much tamer than the sparrows I have observed in desert places, where they seldom see a human being. Nevertheless young sparrows in England are very much tamer than old birds, as anyone may see for himself. During the past summer, while living near Kew Gardens, I watched the sparrows a great deal, and fed forty or fifty of them every day from a back window. The bread and seed was thrown on to a low roof just outside the window, and I noticed that the young birds when first able to fly were always brought by the parents to this feeding place, and that after two or three visits they would begin to come of their own accord. At such times they would venture quite close to me, showing as little suspicion as young chickens. The adults, however, although so much less shy than birds of other species, were extremely suspicious, snatching up the bread and flying away; or, if they remained, hopping about in a startled manner, craning their necks to view me, and making so many gestures and motions, and little chirps of alarm, that presently the young would become infected with fear. The lesson was taught them in a surprisingly short time; their suspicion was seen to increase day by day, and about a week later they were scarcely to be distinguished, in behaviour from the adults. It is plain that, with these little birds, fear of man is an associate feeling, and that, unless it had been taught them, his presence would trouble them as little as does that of horse, sheep, or cow. But how about the larger species, used as food, and which have had a longer and sadder experience of man’s destructive power?

The rhea, or South American ostrich, philosophers tell us, is a very ancient bird on the earth; and from its great size and inability to escape by flight, and its excellence as food, especially to savages, who prefer fat rank-flavoured flesh, it must have been systematically persecuted by man as long as, or longer than, any bird now existing on the globe. If fear of man ever becomes hereditary in birds, we ought certainly to find some trace of such an instinct in this species. I have been unable to detect any, though I have observed scores of young rheas in captivity, taken before the parent bird had taught them what to fear. I also once kept a brood myself, captured just after they had hatched out. With regard to food they were almost, or perhaps quite, independent, spending most of the time catching flies, grasshoppers, and other insects with surprising dexterity; but of the dangers encompassing the young rhea they knew absolutely frothing. They would follow me about as if they took me for their parent; and, whenever I imitated the loud snorting or rasping warning-call emitted the old bird in moments of danger, they would to me in the greatest terror, though no animal was in sight, and, squatting at my feet, endeavour to conceal themselves by thrusting their heads and long necks up my trousers. If I had caused a person to dress in white or yellow clothes for several consecutive days, and had then uttered the warning cry each time he showed himself to the birds, I have no doubt that they would soon have acquired a habit of running in terror from him, even without the warning cry, and that the fear of a person in white or yellow would have continued all their lives. Up to within about twenty years ago, rheas were seldom or never shot in La Plata and Patagonia, but were always hunted on horseback and caught with the bolas. The sight of a mounted man would set them off at once, while a person on foot could walk quite openly to within easy shooting distance of them; yet their fear of a horseman dates only two hundred years back–a very short time, when we consider that, before the Indian borrowed the horse from the invader, he must have systematically pursued the rhea on foot for centuries. The rhea changed its habits when the hunter changed his, and now, if an _estanciero_ puts down ostrich hunting on his estate, in a very few years the birds, although wild birds still, become as fearless and familiar as domestic animals. I have known old and ill-tempered males to become a perfect nuisance on some estancias, running after and attacking every person, whether on foot or on horseback, that ventured near them. An old instinct of a whole race could not be thus readily lost here and there on isolated estates wherever a proprietor chose to protect his birds for half a dozen years.

I suppose the Talegallus–the best-known brush-turkey–must be looked on as an exception to all other birds with regard to the point I am considering; for this abnormal form buries its eggs in the huge mound made by the male, and troubles herself no more about them. When the young is fully developed it simply kicks the coffin to pieces in which its mother interred it, and, burrowing its way up to the sunshine, enters on the pleasures and pains of an independent existence from earliest infancy–that is, if a species born into the world in full possession of all the wisdom of the ancients, can be said ever to know infancy. At all events, from Mr. Bartlett’s observations on the young hatched in the Zoological Gardens, it appears that they took no notice of the old birds, but lived quite independently from the moment they came out of the ground, even flying up into a tree and roosting separately at night. I am not sure, however, that these observations are quite conclusive; for it is certain that captivity plays strange pranks with the instincts of some species, and it is just possible that in a state of nature the old birds exercise at first some slight parental supervision, and, like all other species, have a peculiar cry to warn the young of the dangers to be avoided. If this is not so, then the young Talegallus must fly or hide with instinctive tear from every living thing that approaches it. I, at any rate, find it hard to believe that it has a knowledge, independent of experience, of the different habits of man and kangaroo, and dis-criminates at first sight between animals that are dangerous to it and those that are not. This interesting point will probably never be determined, as, most unhappily, the Australians are just now zealously engaged in exterminating their most wonderful bird for the sake of its miserable flesh; and with less excuse than the Maories could plead with regard to the moa, since they cannot deny that they have mutton and rabbit enough to satisfy hunger.

Whether birds fear or have instinctive knowledge of any of their enemies is a much larger question. Species that run freely on the ground from the time of quitting the shell know their proper food, and avoid whatever is injurious. Have all young birds a similarly discriminating instinct with regard to their enemies? Darwin says, “Fear of any particular enemy is certainly an instinctive quality, as may be seen in nestling birds.” Here, even man seems to be included among the enemies feared instinctively; and in another passage he says, “Young chickens have lost, wholly from habit, that fear of the dog and cat which, no doubt, was originally instinctive in them.” My own observations point to a contrary conclusion; and I may say that I have had unrivalled opportunities for studying the habits of young birds.

Animals of all classes, old and young, shrink with instinctive fear from any strange object approaching them. A piece of newspaper carried accidentally by the wind is as great an object of terror to an inexperienced young bird as a buzzard sweeping down with death in its talons. Among birds not yet able to fly there are, however, some curious exceptions; thus the young of most owls and pigeons are excited to anger rather than fear, and, puffing themselves up, snap and strike at an intruder with their beaks. Other fledglings simply shrink down in the nest or squat close on the ground, their fear, apparently, being in proportion to the suddenness with which the strange animal or object comes on them; but, if the deadliest enemy approaches with slow caution, as snakes do–and snakes must be very ancient enemies to birds–there is no fear or suspicion shown, even when the enemy is in full view and about to strike. This, it will be understood, is when no warning-cry is uttered by the parent bird. This shrinking, and, in some cases, hiding from an object corning swiftly towards them, is the “wildness_”_ of young birds, which, Darwin says again, is greater in wild than in domestic species. Of the extreme tameness of the young rhea I have already spoken; I have also observed young tinamous, plovers, coots, &c., hatched by fowls, and found them as incapable of distinguishing friend from foe as the young of domestic birds. The only difference between the young of wild and tame is that the former are, as a rule, much more sprightly and active. But there are many exceptions; and if this greater alertness and activity is what is meant by “wildness,” then the young of some wild birds–rhea, crested screamer, &c.–are actually much tamer than our newly-hatched chickens and ducklings.

To return to what may be seen in nestling birds, n very young, and before their education has begun, if quietly approached and touched, they open their bills and take food as readily from a man as from the parent bird. But if while being thus fed the parent returns and emits the warning note, they instantly cease their hunger-cries, close their gaping mouths, and crouch down frightened in the nest. This fear caused by the parent bird’s warning note begins to manifest itself even before the young are hatched–and my observations on this point refer to several species in three widely separated orders. When the little prisoner is hammering at its shell, and uttering its feeble _peep,_ as if begging to be let out, if the warning note is uttered, even at a considerable distance, the strokes and complaining instantly cease, and the chick will then remain quiescent in the shell for a long time, or until the parent, by a changed note, conveys to it an intimation that the danger is over. Another proof that the nestling has absolutely no instinctive knowledge of particular enemies, but is taught to fear them by the parents, is to be found in the striking contrast between the habits of parasitical and genuine young in the nest, and after they have left it, while still unable to find their own food. I have had no opportunities of observing the habits of the young cuckoo in England with regard to this point, and do not know whether other observers have paid any attention to the matter or not, but I am very familiar with the manners of the parasitical starling or cow-bird of South America. The warning cries of the foster parent have no effect on the young cow-bird at any time. Until they are able to fly they will readily devour worms from the hand of a man, even when the old birds are hovering close by and screaming their danger notes, and while their own young, if the parasite has allowed any to survive in the nest, are crouching down in the greatest fear. After the cow-bird has left the nest it is still stupidly tame, and more than once I have seen one carried off from its elevated perch by a milvago hawk, when, if it had understood the warning cry of the foster parent, it would have dropped down into the bush or grass and escaped. But as soon as the young cow-birds are able to shift for themselves, and begin to associate with their own kind, their habits change, and they become suspicious and wild like other birds.

On this point–the later period at which the parasitical young bird acquires fear of man–and also bearing on the whole subject under discussion, I shall add here some observations I once made on a dove hatched and reared by a pigeon at my home on the pampas. A very large ombu tree grew not far from the dove-cote, and some of the pigeons used to make their nests on the lower horizontal branches. One summer a dove of the most common species, Zenaida maculata, in size a third less than the domestic pigeon, chanced to drop an egg in one of these nests, and a young dove was hatched and reared; and, in due time, when able to fly, it was brought to the dove-cote. I watched it a great deal, and it was evident that this foster-young, though’ with the pigeons, was not nor ever would be of them, for it could not take kiudly to their flippant flirty ways. Whenever a male approached it, and with guttural noises and strange gestures made a pompous declaration of amorous feelings, the dove would strike vigorously at its undesirable lover, and drive him off, big as he was; and, as a rule, it would sit apart, afoot or so, from the others. The dove was also a male; but its male companions, with instinct tainted by domestication, were ignorant alike of its sex and different species. Now, it chanced that my pigeons, never being fed and always finding their own living on the plain like wild birds, were, although still domestic, not nearly so tame as pigeons usually are in England. They would not allow a person to approach within two or three yards of them without flying, and if grain was thrown to them they would come to it very suspiciously, or not at all. And, of course, the young pigeons always acquired the exact degree of suspicion shown by the adults as soon as they were able to fly and consort with the others. But the foundling Zenaida did not know what their startled gestures and notes of fear meant when a person approached too near, and as he saw none of his own kind, he did not acquire their suspicious habit. On the contrary, he was perfectly tame, although by parentage a wild bird, and showed no more fear of a man than of a horse. Throughout the winter it remained with the pigeons, going afield every day with them, and returning to the dove-cote; but as spring approached the slight tie which united him to them began to be loosened; their company grew less and less congenial, and he began to lead a solitary life. But he did not go to the trees yet. He came to the house, and his favourite perch was on the low overhanging roof of a vine-covered porch, just over the main entrance. Here he would pass several hours every day, taking no notice of the people passing in and out at all times; and when the weather grew warm he would swell out his breast and coo mournfully by the hour for our pleasure.

We can, no doubt, learn best by observing the behaviour of nestlings and young birds; nevertheless, I find much even in the confirmed habits of adults to strengthen me in the belief that fear of particular enemies is in nearly all cases–for I will not say all–the result of experience and tradition.

Hawks are the most open, violent, and persistent enemies birds have; and it is really wonderful to see how well the persecuted kinds appear to know the power for mischief possessed by different raptorial species, and how exactly the amount of alarm exhibited is in proportion to the extent of the danger to be apprehended. Some raptors never attack birds, others only occasionally; still others prey only on the young and feeble; and, speaking of La Plata district, where I have observed hawks, from the milvago chimango–chiefly a carrion-eater–to the destructive peregrine falcon, there is a very great variety of predatory habits, and all degrees of courage to be found; yet all these raptors are treated differently by species liable to be preyed on, and have just as much respect paid them as their strength and daring entitles them to, and no more, So much discrimination must seem almost incredible to those who are not very familiar with the manners of wild birds; I do not think it could exist if the fear shown resulted from instinct or inherited habit. There would be no end to the blunders of such an instinct as that; and in regions where hawks are extremely abundant most of the birds would bo in a constant state of trepidation. On the pampas the appearance of the comparatively harmless chimango excites not the least alarm among small birds, yet at a distance it closely resembles a henharrier, and it also readily attacks young, sick, and wounded birds; all others know how little they have to fear from it. When it appears unexpectedly, sweeping over a hedge or grove with a rapid flight, it is sometimes mistaken for a more dangerous species; there is then a little flutter of alarm, some birds springing into the air, but in two or three seconds of time they discover their mistake, and settle down quietly again, taking no further notice of the despised carrion-eater. On the other hand, I have frequently mistaken a harrier (Circus cinereus, in the brown state of plumage) for a chimango, and have only discovered my mistake by seeing the commotion among the small birds. The harrier I have mentioned, also the C. macropterus, feed partly on small birds, which they flush from the ground and strike down with their claws. When the harrier appears moving along with a loitering flight near the surface, it is everywhere attended by a little whirlwind of alarm, small birds screaming or chirping excitedly and diving into the grass or bushes; but the alarm does not spread far, and subsides as soon as the hawk has passed on its way. Buzzards (Buteo and Urubitinga) are much more feared, and create a more widespread alarm, and they ars certainly more destructive to birds than harriers. Another curious instance is that of the sociable hawk (Rostrhanrus sociabilis). This bird spends the summer and breeds in marshes in La Plata, and birds pay no attention to it, for it feeds exclusively on water-snails (Ampullaria). But when it visits woods and plantations to roost, during migration, its appearance creates as much alarm as that of a true buzzard, which it closely resembles. Wood-birds, unaccustomed to see it, do not know its peculiar preying habits, and how little they need fear its presence. I may also mention that the birds of La Plata seem to fear the kite-like Elanus less than other hawks, and I believe that its singular resemblance to the common gull of the district in its size, snowy-white plumage and manner of flight, has a deceptive effect on most species, and makes them so little suspicious of it,

The wide-ranging peregrine falcon is a common species in La Plata, although, oddly enough, not included in any notice of the avifauna of that region before 1888. The consternation caused among birds by its appearance is vastly greater than that produced by any of the raptors I have mentioned: and it is unquestionably very much more destructive to birds, since it preys exclusively on them, and, as a rule, merely picks the flesh from the head and neck, and leaves the untouched body to its jackal, the carrion-hawk. When the peregrine appears speeding through the air in a straight line at a great height, the feathered world, as far as one able to see, is thrown into the greatest commo-tion, all birds, from the smallest up to species large as duck, ibis, and curlew, rushing about in the air as if distracted. When the falcon has disappeared in the sky, and the wave of terror attending its progress subsides behind it, the birds still continue wild and excited for some time, showing how deeply they have been moved; for, as a rule, fear is exceedingly transitory in its effects on animals,

I must, before concluding this part of my subject, mention another raptor, also a true falcon, but differing from the peregrine in being exclusively a marsh-hawk. In size it is nearly a third less than the male peregrine, which it resembles in its sharp wings and manner of flight, but its flight is much more rapid. The whole plumage, is uniformly of a dark grey colour. Unfortunately, though I have observed it not fewer than a hundred times, I have never been able to procure a specimen, nor do I find that it is like any American falcon already described; so that for the present it must remain nameless. Judging solely from the effect produced by the appearance of this hawk, it must be even more daring and destructive than its larger relation, the peregrine. It flies at a great height, and sometimes descends vertically and with extraordinary velocity, the wings producing a sound like a deep-toned horn. The sound is doubtless produced at will, and is certainly less advantageous to the hawk than to the birds it pursues. No doubt it can afford to despise the wing-power of its quarry; and I have sometimes thought that it takes a tyrannous delight in witnessing the consternation caused by its hollow trumpeting sound. This may be only a fancy, but some hawks do certainly take pleasure in pursuing and striking birds when not seeking prey. The peregrine has been observed, Baird says, capturing birds, only to kill and drop them. Many of the Felidae, we know, evince a similar habit; only these prolong their pleasure by practising a more refined and deliberate cruelty.

The sudden appearance overhead of this hawk produces an effect wonderful to witness. I have frequently seen all the inhabitants of a marsh struck with panic, acting as if demented, and suddenly grown careless to all other dangers; and on such occasions I have looked up confident of seeing the sharp-winged death, suspended above them in the sky. All birds that happen to be on the wing drop down as if shot into the reeds or water; ducks away from the margin stretch out their necks horizontally and drag their bodies, as if wounded, into closer cover; not one bird is found bold enough to rise up and wheel about the marauder–a usual proceeding in the case of other hawks; while, at every sudden stoop the falcon makes, threatening to dash down on his prey, a low cry of terror rises from the birds beneath; a sound expressive of an emotion so contagious that it quickly runs like a murmur all over the marsh, as if a gust of wind had swept moaning through, the rushes. As long as the falcon hangs overhead, always at a height of about forty yards, threatening at intervals to dash down, this murmuring sound, made up of many hundreds of individual cries, is heard swelling and dying away, and occasionally, when he drops lower than usual, rising to a sharp scream of terror.

Sometimes when I have been riding over marshy ground, one of these hawks has placed himself directly over my head, within fifteen or twenty yards of me; and it has perhaps acquired the habit of following a horseman in this way in order to strike at any birds driven up. On one occasion my horse almost trod on a couple of snipe squatting terrified in the short grass. The instant they rose the hawk struck at one, the end of his wing violently smiting my cheek as he stooped, and striking at the snipe on a level with the knees of my horse. The snipe escaped by diving under the bridle, and immediately dropped down on the other side of me, and the hawk, rising up, flew away.

To return. I think I am justified in believing that fear of hawks, like fear of men, is, in very nearly all cases, the result of experience and tradition. Nevertheless, I think it probable that in some species which have always lived in the open, continually exposed to attack, and which are preferred as food by raptors, such as duck, snipe, and plover, the fear of the falcon may be an inherited habit. Among passerine birds I am also inclined to think that swallows show inherited fear of hawks. Swallows and humming-birds have least to fear from raptors; yet, while humming-birds readily pursue and tease hawks, thinking as little of them as of pigeons or herons, swallows everywhere manifest the greatest terror at the approach of a true falcon; and they also fear other birds of prey, though in a much less degree. It has been said that the European hobby occasionally catches swal-lows on the wing, but this seems a rare and exceptional habit, and in South America I have never seen any bird of prey attempt the pursuit of a swallow. The question then arises, how did this unnecessary fear, so universal in swallows, originate? Can it be a survival of a far past–a time when some wide-ranging small falcon, aerial in habits as the swallow itself, preyed by preference on hirundines only ?

[NOTE.-Herbert Spencer, who accepts Darwin’s inference, explains how the fear of man, acquired by experience, becomes instinctive in birds, in the following passage: “It is well known that in newly-discovered lands not inhabited by man, birds are so devoid of fear as to allow themselves to be knocked over with sticks; but that, in the course of generations, they acquire such a dread of man as to fly on his approach: and that this dread is manifested by young as well as by old. Now unless this change be ascribed to the killing-off of the least fearful, and the preservation and multiplication of the most fearful which, considering the comparatively small number killed by man, is an inadequate cause, it must be ascribed to accumulated experience; and each experience must be held to have a share in producing it. We must conclude that in each bird that escapes with injuries inflicted by man, or is alarmed by the outcries of other members of the flock (gregarious creatures of any intelligence being necessarily more or less sympathetic), there is established an association of ideas between the human aspect and the pains, direct and in-direct, suffered from human agency. And we must further con-clude, that the state of consciousness which compels the bird to take flight, is at first nothing more than an ideal reproduction of those painful impressions which before followed man’s approach; that such ideal reproduction becomes more vivid and more massive as the painful experiences, direct or sympathetic, increase; and that thus the emotion, in its incipient state, is nothing else than an aggregation of the revived pains before experience.

“As, in the course of generations, the young birds of this race begin to display a fear of man before yet they have been injured by him, it is an unavoidable inference that the nervous system of the race has been organically modified by these experiences, we have no choice but to conclude, that when a young bird is led to fly, it is because the impression produced in its senses by the approaching man entails, through an incipiently reflex action, a partial excitement of all those nerves which in its ancestors had been excited under the like conditions; that this partial excitement has its accompanying painful consciousness, and that the vague painful consciousness thus arising constitutes emotion proper–_emotion undecomposable into specific experiences, and, therefore, seemingly homogeneous”_ (Essays, vol. i. p. 320.)]

It is comforting to know that the “unavoidable inference” is, after all, erroneous, and that the nervous system in birds has not yet been organically altered as a result of man’s persecution; for in that case it would take long to undo the mischief, and we should be indeed far from that “better friendship” with the children of the air which many of us would like to see.

CHAPTER VI.

PARENTAL AND EARLY INSTINCTS.

Under this heading I have put together several notes from my journals on subjects which have no connection with each other, except that they relate chiefly to the parental instincts of some animals I have observed, and to the instincts of the young at a very early period of life.

While taking bats one day in December, I captured a female of our common Buenos Ayrean species (Molossus bonariensis), with her two young attached to her, so large that it seemed incredible she should be able to fly and take insects with such a weight to drag her down. The young were about a third less in size than the mother, so that she had to carry a weight greatly exceeding that of her own body. They were fastened to her breast and belly, one on each side, as when first born; and, possibly, the young bat does not change its position, or move, like the young developed opossum, to other parts of the body, until mature enough to begin an independent life. On forcibly separating them from their parent, I found that they were not yet able to fly, but when set free fluttered feebly to the ground. This bat certainly appeared more burdened with its young than any animal I had ever observed. I have seen an old female opossum (Didelphys azarae) with eleven young, large as old rats–the mother being less than a cat in size–all clinging to various parts of her body; yet able to climb swiftly and with the greatest agility in the higher branches of a tree. The actual weight was in this case relatively much greater than in that of the female bat: but then the opossum never quitted its hold on the tree, and it also supplemented its hand-like feet, furnished with crooked claws, with its teeth and long prehensile tail. The poor bat had to seek its living in the empty air, pursuing its prey with the swiftness of a swallow, and it seemed wonderful to me that she should have been able to carry about that great burden with her one pair of wings, and withal to be active enough to supply herself and her young with food.

In the end I released her, and saw her fly away and disappear among the trees, after which I put back the two young bats in the place I had taken them from, among the thick-clustering foliage of a small acacia tree. When set free they began to work their way upwards through the leaves and slender twigs in the most adroit manner, catching a twig with their teeth, then embracing a whole cluster of leaves with their wings, just as a person would take up a quantity of loose clothes and hold them tight by pressing them against the chest. The body would then emerge above the clasped leaves, and a higher twig would be caught by the teeth; and so on successively, until they had got as high as they wished, when they proceeded to hook themselves to a twig and assume the inverted position side by side; after which, one drew in its head and went to sleep, while the other began licking the end of its wing, where my finger and thumb had pressed the delicate membrane. Later in the day I attempted to feed them with small insects, but they rejected my friendly attentions in the most unmistakable manner, snapping viciously at me every time I approached them. In the evening, I stationed myself close to the tree, and presently had the satisfaction of seeing the mother return, flying straight to the spot where I had taken her, and in a few moments she was away again and over the trees with her twins.

Assuming that these two young bats had, before I found them, existed like parasites clinging to the parent, their adroit actions when liberated, and their angry demonstrations at my approach, were very astonishing; for in all other mammals born in a perfectly helpless state, like rodents, weasels, edentates, and even marsupials, the instincts of self-preservation are gradually developed after the period of activity begins, when the mother leads them out, and they play with her and Avith each other. In the bat the instincts must ripen to perfection without exercise or training, and while the animal exists as passively as a fruit on its stem.

I have observed that the helpless young of some of the mammals I have just mentioned seem at first to have no instinctive understanding of the language of alarm and fear in the parent, as all young-birds have, even before their eyes are open. Nor is it necessary that they should have such an instinct, since, in most cases, they are well concealed in kennels or other safe places; but when, through some accident, they are exposed, the want of such an instinct makes the task of protecting them doubly hard for the parent. I once surprised a weasel (Galictis barbara) in the act of removing her young, or conducting them, rather; and when she was forced to quit them, although still keeping close by, and uttering the most piercing cries of anger and solicitude, the young continued piteously crying out in their shrill voices and moving about in circles, without making the slightest attempt to escape, or to conceal themselves, as young birds do.

Some field mice breed on the surface of the ground in ill-constructed nests, and their young are certainly the most helpless things in nature. It is possible that where this dangerous habit exists, the parent has some admirable complex instincts to safeguard her young, in addition to the ordinary instincts of most animals of this kind. This idea was suggested to me by the action of a female mouse which I witnessed by chance. While walking in a field of stubble one day in autumn, near Buenos Ayres, I suddenly heard, issuing from near my feet, a chorus of shrill squealing voices–the familiar excessively sharp little needles of sound emitted by young, blind and naked mice, when they are disturbed or in pain. Looking down, I saw close to my foot a nest of them–there were nine in all, wriggling about and squealing; for the parent, frightened at my step, had just sprung from them, overturning in her hurry to escape the slight loosely-felted dome of fine grass and thistledown which had covered them. I saw her running away, but after going six or seven yards she stopped, and, turning partly round so as to watch me, waited in fear and trembling. I remained perfectly motionless–a sure way to allay fear and suspicion in any wild creature,–and in a few moments she returned, but with the utmost caution, frequently pausing to start and tremble, and masking her approach with corn stumps and little inequalities in the surface of the ground, until, reaching the nest, she took one of the young in her mouth, and ran rapidly away to a distance of eight or nine yards and concealed it in a tuft of dry grass.

Leaving it, she returned a second time, in the same cautious manner, and taking another, ran with it to the same spot, and concealed it along with the first. It was curious that the first young mouse had continued squealing after being hidden by the mother, for I could hear it distinctly, the air being very still, but when the second mouse had been placed with it, the squealing ceased. A third time the old mouse came, and then instead of going to the same spot, as I had expected, she ran off in an opposite direction and disappeared among the dry weeds; a fourth was carried to the same place as the third; and in this way they were all removed to a distance of some yards from the nest, and placed in couples, until the last and odd one remained. In due time she came for it, and ran away with it in a new direction, and was soon out of sight; and although I waited fully ten minutes, she did not return; nor could I afterwards find any of the young mice when I looked for them, or even hear them squeal.

I have frequently observed newly-born lambs on the pampas, and have never failed to be surprised at the extreme imbecility they display in their actions; although this may be due partly to inherited degeneracy caused by domestication. This imbecile condition continues for two, sometimes for three days, during which time the lamb apparently acts purely from instincts, which are far from perfect; but after that, experience and its dam teach it a better way. When born its first impulse is to struggle up on to its feet; its second to suck, but here it does not discriminate like the newly-hatched bird that picks up its proper food, or it does not know what to suck. It will take into its mouth whatever comes near, in most cases a tuft of wool on its dam’s neck; and at this it will continue sucking for an indefinite time. It is highly probable that the strong-smelling secretion of the sheep’s udder attracts the lamb at length to that part; and that without something of the kind to guide it, in many cases it would actually starve without finding the teats. I have often seen lambs many hours after birth still confining their attention to the most accessible locks of wool on the neck or fore legs of the dams, and believe that in such cases the long time it took them to find the source of nourishment arose from a defective sense of smell. Its next important instinct, which comes into play from the moment it can stand on its feet, impels it to follow after any object receding from it, and, on the other hand, to run from anything approaching it. If the dam turns round and approaches it from even a very short distance, it will start back and run from her in fear, and will not understand her voice when she bleats to it: at the same time it will confidently follow after a man, dog, horse, or any other animal moving from it. A very common experience on the pampas, in the sheep-country, is to see a lamb start up from sleep and follow the rider, running along close to the heels of the horse. This is distressing to a merciful man, tor he cannot shake the little simpleton off, and if he rides on, no matter how fast, it will keep up him, or keep him in sight, for half a mile or a mile, and never recover its dam. The gaucho, who is not merciful, frequently saves himself all trouble and delay by knocking it senseless with a blow of his whip-handle, and without checking his horse. I have seen a lamb, about two days old, start up from sleep, and immediately start off in pursuit of a puff ball about as big as a man’s head, carried past it over the smooth turf by the wind, and chase it for a distance of five hundred yards, until the dry ball was brought to a stop by a tuft of coarse grass. This blundering instiuct is quickly laid aside when the lamb has learned to distinguish its dam from other objects, and its dam’s voice from other sounds. When four or five days old it will start from sleep, but instead of rushing blindly away after any receding object, it first looks about it, and will then recognize and run to its dam.

I have often been struck with the superiority of the pampa or creolla–the old native breed of sheep–in the greater vigour of the young when born over the improved European varieties. The pampa descends to us from the first sheep introduced into La Plata about three centuries ago, and is a tall, gaunt bony animal, with lean dry flesh, like venison, and long straight wool, like goats’ hair. In their struggle for existence in a country subject to sudden great changes of temperature, to drought, and failure of grass, they have in a great measure lost the qualities which make the sheep valuable to man as a food and wool-producing animal; but on the other hand they have to some extent recovered the vigour of a wild animal, being hardy enough to exist without any shelter, and requiring from their master man only protection from the larger carnivores. They are keen-scented, swift of foot and Wonderfully active, and thrive where other breeds would quickly starve. I have often seen a lamb dropped on the frosty ground in bitterly cold windy weather in midwinter, and in less than five seconds struggle to its feet, and seem as vigorous as any day-old lamb of other breeds. The dam, impatient at the short delay, and not waiting to give it suck, has then started off at a brisk trot after the flock, scattered and galloping before the wind like huanacos rather than sheep, with the lamb, scarcely a minute in the world, running freely at her side. Notwithstanding its great vigour it has been proved that the pampa sheep has not so far outgrown the domestic taint as to be able to maintain its own existence when left entirely to itself. During the first half of this century, when cattle-breeding began to be profitable, and wool was not worth the trouble of shearing, and the gaucho workman would not eat mutton when beef was to be had, some of the estancieros on the southern pampas determined to get rid of their sheep, which were of no value to them; and many flocks were driven a distance out and lost in the wilds. Out of many thousands thus turned loose to shift for themselves, not one pair survived to propagate a new race of feral sheep; in a short time pumas, wild dogs, and other beasts of prey, had destroyed them all. The sterling qualities of the pampa sheep had their value in other times; at present the improved kinds are alone considered worth having, and the original sheep of the country is now rapidly disappearing, though still found in remote and poor districts, especially in the province of Cordova; and probably before long it will become extinct, together with the curious pug-nosed cow of the pampas.

I have had frequent opportunities of observing the young, from one to three days old, of the Cervus campestris–the common deer of the pampas, and the perfection of its instincts at that tender age seem very wonderful in a ruminant. When the doe with, fawn is approached by a horseman, even when accompanied with dogs, she stands perfectly motionless, gazing fixedly at the enemy, the fawn motionless at her side; and suddenly, as if at a preconcerted signal, the fawn rushes directly away from her at its utmost speed; and going to a distance of six hundred to a thousand yards conceals itself in a hollow in the ground or among the long grass, lying down very close with neck stretched out horizontally, and will thus remain until sought by the dam. When very young if found in its hiding-place it will allow itself to be taken, making no further effort to escape. After the fawn has run away the doe still maintains her statuesque attitude, as if resolved to await the onset, and only when the dogs are close to her she also rushes away, but invariably in a direction as nearly opposite to that taken by the fawn as possible. At first she runs slowly, with a limping gait, and frequently pausing, as if to entice her enemies on, like a partridge, duck or plover when driven from its young; but as they begin to press her more closely her speed increases, becoming greater the further she succeeds in leading them from the starting-point.

The alarm-cry of this deer is a peculiar whistling bark, a low but far-reaching sound; but when approaching a doe with young I have never been able to hear it, nor have I seen any movement on the part of the doe. Yet it is clear that in some mysterious way she inspires the fawn with sudden violent fear; while the fawn, on its side, instead of being affected like the young in other mammals, and sticking closer to its mother, acts in a contrary way, and runs from her.

Of the birds I am acquainted with, the beautiful jacana (Parra jacana) appears to come into the world with its faculties and powers in the most advanced state. It is, in fact, ready to begin active life from the very moment of leaving the shell, as I once accidentally observed. I found a nest on a small mound of earth in a shallow lagoon, containing four eggs, with the shells already chipped by the birds in them. Two yards from the small nest mound there was a second mound covered with coarse grass. I got off my horse to examine the nest, and the old birds, excited beyond measure, fluttered round me close by pouring out their shrill rapidly-reiterated cries in an unbroken stream, sounding very much like a policeman’s rattle. While I was looking closely at one of the eggs lying on the palm of my hand, all at once the cracked shell parted, and at the same moment the young bird leaped from my hand and fell into the water. I am quite sure that the young bird’s sudden escape from the shell and my hand was the result of a violent effort on its part to free itself; and it was doubtless inspired to make the effort by the loud persistent screaming of the parent birds, which it heard while in the shell. Stooping to pick it up to save it from perishing, I soon saw that my assistance was not required, for immediately on dropping into the water, it put out its neck, and with the body nearly submerged, like a wounded duck trying to escape observation, it swam rapidly to the second small mound I have mentioned, and, escaping from the water, concealed itself in the grass, lying close and perfectly motionless like a young plover.

In the case of the pampa or creolla sheep, I have shown that during its long, rough life in La Plata, this variety has in some measure recovered the natural vigour and ability to maintain existence in adverse circumstances of its wild ancestors. As much can be said of the creolla fowl of the pampas; and some observations of mine on the habits of this variety will perhaps serve to throw light on a vexed question of Natural History–namely, the cackling of the hen after laying, an instinct which has been described as “useless” and “disadvantageous.” In fowls that live unconfined, and which are allowed to lay where they like, the instinct, as we know it, is certainly detrimental, since egg-eating dogs and pigs soon learn the cause of the outcry, and acquire a habit of rushing off to find the egg when they hear it. The question then arises: Does the wild jungle fowl possess the same pernicious instinct?

The creolla is no doubt the descendant of the fowl originally introduced about three centuries ago by the first colonists in La Plata, and has probably not only been uncrossed with any other improved variety, such as are now fast taking its place, and has lived a much freer life than is usual with the fowl in Europe. It is a rather small, lean, extremely active bird, lays about a dozen eggs, and hatches them all, and is of a yellowish red colour–a hue which is common, I believe, in the old barn-door fowl of England. The creolla fowl is strong on the wing, and much more carnivorous and rapacious in habits than other breeds; mice, frogs, and small snakes are eagerly hunted and devoured by it. At my home on the pampas a number of these fowls were kept, and were allowed to range freely about the plantation, which was large, and the adjacent grounds, where there were thickets of giant cardoon thistle, red-weed, thorn apple, &c. They always nested at a distance from the house, and it was almost impossible ever to find their eggs, on account of the extreme circumspection they observed in going to and from their nests; and when they succeeded in escaping foxes, skunks, weasels, and opossums, which, strange to say, they often did, they would rear their chickens away out of sight and hearing of the house, and only bring them home when winter deprived them of their leafy covering and made food scarce. During the summer, in my rambles about the plantation, T would occasionally surprise one of these half-wild hens with her brood; her distracted screams and motions would then cause her chicks to scatter and vanish in all directions, and, until the supposed danger was past, they would lie as close and well-concealed as young partridges. These fowls in summer always lived in small parties, each party composed of one cock and as many hens as he could collect–usually three or four. Each family occupied its own feeding ground, where it would pass a greater portion of each day. The hen would nest at a considerable distance from the feeding ground, sometimes as far as four or five hundred yards away. After laying an egg she would quit the nest, not walking from it as other fowls do, but flying, the flight extending to a distance of from fifteen to about fifty yards; after which, still keeping silence, she would walk or run, until, arrived at the feeding ground, she would begin to cackle. At once the cock, if within hearing, would utter a responsive cackle, whereupon she would run to him and cackle no more. Frequently the cackling call-note would not be uttered more than two or three times, sometimes only once, and in a much lower tone than in fowls of other breeds.

If we may assume that these fowls, in their long, semi-independent existence in La Plata, have reverted to the original instincts of the wild Gallus bankiva, we can see here how advantageous the cackling instinct must be in enabling the hen in dense tropical jungles to rejoin the flock after laying an egg. If there are egg-eating animals in the jungle intelligent enough to discover the meaning of such a short, subdued cackling call, they would still be unable to find the nest by going back on the bird’s scent, since she flies from the nest in the first place; and the wild bird probably flies further than the creolla hen of La Plata. The clamorous cackling of our fowls would appear then to be nothing more than a perversion of a very useful instinct.

CHAPTER VII.

THE MEPHITIC SKUNK.

It might possibly give the reader some faint conception of the odious character of this creature (for adjectives are weak to describo it) when I say that, in talking to strangers from abroad, I have never thought it necessary to speak of sunstroke, jaguars, or the assassin’s knife, but have never omitted to warn them of the skunk, minutely describing its habits and personal appearance.

I knew an Englishman who, on taking a first gallop across the pampas, saw one, and, quickly dismounting, hurled himself bodily on to it to effect its capture. Poor man! he did not know that the little animal is never unwilling to be caught. Men have been blinded for ever by a discharge of the fiery liquid full in their faces. On a mucous membrane it burns like sulphuric acid, say the unfortunates who have had the experience. How does nature protect the skunk itself from the injurious effects of its potent fluid? I have not unfrequently found individuals stone-blind, sometimes moving so briskly about that the blindness must have been of long standing–very possibly in some cases an accidental drop discharged by the animal itself has caused the loss of sight. When coming to close quarters with a skunk, by covering up the face, one’s clothes only are ruined. But this is not all one has to fear from an encounter; the worst is that effluvium, after which crushed garlic is lavender, which tortures the olfactory nerves, and appears to pervade the whole system like a pestilent ether, nauseating one until sea-sickness seems almost a pleasant sensation in comparison.

To those who know the skunk only from reputation, my words might seem too strong; many, however, who have come to close quarters with the little animal will think them ridiculously weak. And consider what must the feelings be of one who has had the following experience–not an uncommon experience on the pampas. There is to be a dance at a neighbouring house a few miles away; he has been looking forward to it, and, dressing himself with due care, mounts his horse and sets out full of joyous anticipations. It is a dark windy evening, but there is a convenient bridle-path through the dense thicket of giant thistles, and striking it he puts his horse into a swinging gallop. Unhappily the path is already occupied by a skunk, invisible in the darkness, that, in obedience to the promptings of its insane instinct, refuses to get out of it, until the flying hoofs hit it and sand it like a well-kicked football into the thistles. But the forefoot of the horse, up as high as his knees perhaps, have been sprinkled, and the rider, after coming out into the open, dismounts and walks away twenty yards from his animal, and literally _smells_ himself all over, and with a feeling of profound relief pronounces himself Not the minutest drop of the diabolical spray has touched his dancing shoes! Springing into the saddle he proceeds to his journey’s end, is warmly welcomed by his host, and speedily forgetting his slight misadventure, mingles with a happy crowd of friends. In a little while people begin exchanging whispers and significant glances; men are seen smiling at nothing in particular; the hostess wears a clouded face; the ladies cough and put their scented handkerchiefs to their noses, and presently they begin to feel faint and retire from the room. Our hero begins to notice that there is something wrong, and presently discovers its cause; he, unhappily, has been the last person in the room to remark that familiar but most abominable odour, rising like a deadly exhalation from the floor, conquering all other odours, and every moment becoming more powerful. A drop _has_ touched his shoe after all; and fearing to be found out, and edging towards the door, he makes his escape, and is speedily riding home again; knowing full well that his sudden and early departure from the scene will be quickly discovered and set down to the right cause.

In that not always trustworthy book _The Natural History of Chili,_ Molina tells us how they deal with the animal in the trans-Andine regions. “When one appears,” he says, “some of the company begiu by caressing it, until an opportunity offers for one of them to seize it by the tail. In this position the muscles become contracted, the animal is unable to eject its fluid, and is quickly despatched.” One might just as well talk of caressing a cobra de capello; yet this laughable fiction finds believers all over South and North America. Professor Baird gravely introduces it into his great work on the mammalia. I was once talking about animals in a rancho, when a person present (an Argentine officer) told that, while visiting an Indian encampment, he had asked the savages how they contrived to kill skunks without making even a life in the desert intolerable. A grave old Cacique informed him that the secret was to go boldly up to the animal, take it by the tail, and despatch it; for, he said, when you fear it not at all, then it respects your courage and dies like a lamb–sweetly. The officer, continuing his story, said that on quitting the Indian camp he started a skunk, and, glad of an opportunity to test the truth of what he had heard, dismounted and proceeded to put the Indian plan in practice. Here the story abruptly ended, and when I eagerly demanded to hear the sequel, the amateur hunter of furs lit a cigarette and vacantly watched the ascending smoke. The Indians aro grave jokers, they seldom smile; and this old traditional skunk-joke, which has run the length of a continent, finding its way into many wise books, is their revenge on a superior race.

I have shot a great many eagles, and occasionally a carancho (Polyborus tharus), with the plumage smelling strongly of skunk, which shows that these birds, pressed by hunger, often commit the fearful mistake of attacking the animal. My friend Mr. Ernest Gibson, of Buenos Ayres, in a communication to the _Ibis,_ describes an encounter he actually witnessed between a carancho and a skunk. Riding home one afternoon, he spied a skunk “shuffling along in the erratic manner usual to that odoriferous quadruped;” following it at a very short distance was an eagle-vulture, evidently bent on mischief. Every time the bird came near the bushy tail rose menacingly; then the carancho would fall behind, and, after a few moments’ hesitation, follow on again. At length, growing bolder, it sprung forward, seizing the threatening tail with its claw, but immediately after “began staggering about with dishevelled plumage, tearful eyes, and a profoundly woe-begone expression on its vulture face. The skunk, after turning and regarding its victim with an I-told-you-so look for a few moments, trotted unconcernedly off.”

I was told in Patagonia by a man named Molinos, who was frequently employed by the Government as guide to expeditions in the desert, that everywhere throughout that country the skunk is abundant. Some years ago he was sent with two other men to find and treat with an Indian chief whose whereabouts were not known. Far in the interior Molinos was overtaken by a severe winter, his horses died of thirst and fatigue, and during the three bitterest months of the year he kept himself and his followers alive by eating the flesh of skunks, the only wild animal that never failed them. No doubt, on those vast sterile plains where the skunk abounds, and goes about by day and by night careless of enemies, the terrible nature of its defensive weapon is the first lesson experience teaches to every young eagle, fox, wild cat, and puma.

Dogs kill skunks when made to do so, but it is not a sport they delight in. One moonlight night, at home, I went out to where the dogs, twelve in number, were sleeping: while I stood there a skunk appeared and deliberately came towards me, passing through the dogs where they lay, and one by one as he passed them they rose up, and, with their tails between their legs, skulked off. When made to kill skunks often they become seasoned; but always perform the loathsome task expeditiously, then rush away with frothing mouths to rub their faces in the wet clay and rid themselves of the fiery sensation. At one time I possessed only one dog that could be made to face a skunk, and as the little robbers were very plentiful, and continually coining about the house in their usual open, bold way, it was rather hard for the poor brute. This dog detested them quite as strongly as the others, only he was more obedient, faithful, and brave. Whenever I bade him attack one of them he would come close up to me and look up into my face with piteous pleading eyes, then, finding that he was not to be let off from the repulsive task, he would charge upon the doomed animal with a blind fury wonderful to see. Seizing it between his teeth, he would shake it madly, crushing its bones, then hurl it several feet from him, only to rush again and again upon it to repeat the operation, doubtless with a Caligula-like wish in his frantic breast that all the skunks on the globe had but one backbone.

I was once on a visit to a sheep-farming brother, far away on the southern frontier of Buenos Ayres, and amongst the dogs I found there was one most interesting creature, He was a great, lumbering, stupid, good-tempered brute, so greedy that when you offered him a piece of meat he would swallow half your arm, and so obedient that at a word he would dash himself against the horns of a bull, and face death and danger in any shape. But, my brother told me, he would not face a skunk–he would die first. One day I took him out and found a skunk, and for upwards of half an hour I sat on my horse vainly cheering on my cowardly follower, and urging him to battle. The very sight of the enemy gave him a fit of the shivers; and when the irascible little enemy began to advance against us, going through the performance by means of which he generally puts his foes to flight without resorting to malodorous measures–stamping his little feet in rage, jumping up, spluttering and hissing and flourishing his brush like a warlike banner above his head–then hardly could I restrain my dog from turning tail and flying home in abject terror. My cruel persistence was rewarded at last. Continued shouts, cheers, and hand-clappings began to stir the brute to a kind of frenzy. Torn by conflicting emotions, he began to revolve about the skunk at a lumbering gallop, barking, howling, and bristling up his hair; and at last, shutting his eyes, and with a yell of desperation, he charged. I fully expected to see the enemy torn to pieces in a few seconds, but when the dog was still four or five feet from him the fatal discharge came, and he dropped down as if shot dead. For some time he lay on the earth perfectly motionless, watched and gently bedewed by the victorious skunk; then he got up and crept whining away. Gradually he quickened his pace, finally breaking into a frantic run. In vain I followed him, shouting at the top of my lungs; he stayed not to listen, and very speedily vanished from sight–a white speck on the vast level plain. At noon on the following day he made his appearance, gaunt and befouled with mud, staggering forward like a galvanized skeleton. Too worn out even to eat, he flung himself down, and for hours lay like a dead thing, sleeping off the effects of those few drops of perfume.

Dogs, I concluded, like men, have their idiosyncrasies; but I had gained my point, and proved once more–if any proof were needed–the truth of that noble panegyric of Bacon’s on our faithful servant and companion.

CHAPTER VIII.

MIMICRY AND WARNING COLOURS IN GRASSHOPPERS.

There is in La Plata a large handsome grasshopper (Zoniopoda tarsata), the habits of which in its larva and imago stages are in strange contrast, like those in certain lepidoptera, in which the caterpillars form societies and act in concert. The adult has a greenish protective colouring, brown and green banded thighs, bright red hind wings, seen only during flight. It is solitary and excessively shy in its habits, living always in concealment among the dense foliage near the surface of the ground. The yonng are intensely black, like grasshoppers cut out of jet or ebony, and gregarious in habit, living in bands of forty or fifty to three or four hundred; and so little shy, that they may sometimes be taken up by handfuls before they begin to scatter in alarm. Their gregarious habits and blackness–of all hues in nature the most obvious to the sight–would alone be enough to make them the most conspicuous of insects; but they have still other habits which appear as if specially designed to bring them more prominently into notice. Thus, they all keep so close together at all times as to have their bodies actually touching, and when travelling, move so slowly that the laziest snail might easily overtake and pass one of their bands, and even disappear beyond their limited horizon in a very short time.

They often select an exposed weed to feed on, clustering together on its summit above the surrounding verdure, an exceedingly conspicuous object to every eye in the neighbourhood. They also frequently change their feeding-ground; at such times they deliberately cross wide roads and other open spaces, barren of grass, where, moving so slowly that they scarcely seem to move at all, they look at a distance like a piece of black velvet lying on the ground. Thus in every imaginable way they expose themselves and invite attack; yet, in spite of it all, I have never detected birds preying on them, and I have sometimes kept one of these black societies under observation near my house for several days, watching them at intervals, in places where the trees overhead were the resort of Icterine and tyrant birds, Guira cuckoos, and other species, all great hunters after grasshoppers. A young grasshopper is, moreover, a morsel that seldom comes amiss to any bird, whether insect or seed eater; and, as a rule, it is extremely shy, nimble, and inconspicuous. It seems clear that, although the young Zoniopoda does not mimic in its form any black protected insect, it nevertheless owes its safety to its blackness, together with the habit it possesses of exposing itself in so open and bold a manner. Blackness is so common in large protected insects, as, for instance, in the un-palatable leaf-cutting ants, scorpions, mygale spiders, wasps, and other dangerous kinds, that it is manifestly a “warning colour,” the most universal and best known in nature; and the grasshopper, I believe, furthermore mimics the fearless demeanour of the protected or venomous species, which birds and other insect-eaters know and respect. It might be supposed that the young Zoniopoda is itself unpalatable; but this is scarcely probable, for when the deceptive black mask is once dropped, the excessive shyness, love of concealment, and protective colouring of the insect show that it is much sought after by birds.

While setting this down as an undoubted case of “mimicry,” although it differs in some respects from all other cases I have seen reported, I cannot help remarking that this most useful word appears to be in some danger of losing the meaning originally attached to it in zoology. There are now very few cases of an accidental resemblance found between two species in nature which are not set down by someone to “mimicry,” some in which even the wildest imagination might well fail to see any possible benefit to the supposed mimic. In cases where the outward resemblance of some feeble animal to a widely different and well-protected species, or to some object like a leaf or stick, and where such resemblance is manifestly advantageous and has reacted on and modified the life habits, it is conceivable that slight spontaneous variations in the structure and colouring of the unprotected species have been taken advantage of by the principle of natural selection, and a case of “mimicry” set up, to become more and more perfect in time, as successive casual variations in the same direction increased the resemblance.

The stick-insect is perhaps the most perfect example where resemblance to an inanimate object has been the result aimed at, so to speak, by nature; the resemblance of the volucella fly to the humble-bee, on which it is parasitical, is the most familiar example of one species growing like another to its own advantage, since only by means of its deceptive likeness to the humble-bee is it able to penetrate into the nest with impunity. These two cases, with others of a similar character, were first called cases of “mimicry” by Kirby and Spence, in their ever-delightful _Introduction to Entomology–_an old book, but, curiously enough in these days of popular treatises on all matters of the kind, still the only general work on insects in the English language which one who is not an entomologist can read with pleasure.

A second case of mimicry not yet noticed by any naturalist is seen in another grasshopper, also common in La Plata (Rhomalea speciosa of Thun-berg). This is an extremely elegant insect; the head and thorax chocolate, with cream-coloured markings; the abdomen steel-blue or purple, a colour I have not seen in any other insects of this family. The fore wings have a protective colouring; the hind wings are bright red. When at rest, with the red and purple tints concealed, it is only a very pretty grasshopper, but the instant it takes wing it becomes the fac-simile of a very common wasp of the genus Pepris. These wasps vary greatly in size, some being as large as the hornet; they are solitary, and feed on the honey of flowers and on fruit, and, besides being furnished with stings like other wasps–though their sting is nok so venomous as in other genera–they also, when angry, emit a most abominable odour, and are thus doubly protected against their enemies. Their excessive tameness, slow flight, and indolent motions serve to show that they are not accustomed to be interfered with. All these strong-smelling wasps have steel-blue or purple bodies, and bright red wings. So exactly does the Rhomalea grasshopper mimic the Pepris when flying, that I have been deceived scores of times. I have even seen it on the leaves, and, after it has flown and settled once more, I have gone to look at it again, to make sure that my eyes had not deceived me. It is curious to see how this resemblance has reacted on and modified the habits of the grasshopper. It is a great flyer, and far more aerial in its habits than any other insect I am acquainted with in this family, living always in trees, instead of on or near the surface of the ground. It is abundant in orchards and plantations round Buenos Ayres, where its long and peculiarly soft, breezy note may be heard all summer. If the ancient Athenians possessed so charming an insect as this, their great regard for the grasshopper was not strange: I only wish that the “Athenians of South America,” as my fellow-townsmen sometimes call themselves in moments of exaltation, had a feeling of the samo kind–the regard which does _not_ impale its object on a pin–for the pretty light-hearted songster of their groves and gardens.

When taken in the hand, it has the habit, common to most grasshoppers, of pouring out an inky fluid from its mouth; only the discharge is unusually copious in this species. It has another habit in defending itself which is very curious. When captured it instantly curls its body round, as a wasp does to sting. The suddenness of this action has more than once caused me to drop an insect I had taken, actually thinking for the moment that I had taken hold of a wasp. Whether birds would be deceived and made to drop it or not is a question it would not be easy to settle; but the instinct certainly looks like ‘one of a series of small adaptations, all tending to make the resemblance to a wasp more complete and effective.

CHAPTER IX.

DRAGON-FLY STORMS.

One of the most curious things I have encountered in my observations on animal life relates to a habit of the larger species of dragon-flies inhabiting the Pampas and Patagonia. Dragon-flies are abundant throughout the country wherever there is water. There are several species, all more or less brilliantly coloured. The kinds that excited my wonder, from their habits, are twice as large as the common widely distributed insects, being three inches to four inches in length, and as a rule they are sober-coloured, although there is one species–the largest among them–entirely of a brilliant scarlet. This kind is, however, exceedingly rare. All the different kinds (of the large dragon-flies) when travelling associate together, and occasionally, in a flight composed of countless thousands, one of these brilliant-hued individuals will catch the eye, appearing as conspicuous among the others as a poppy or scarlet geranium growing alone in an otherwise flowerless field. The most common species–and in some cases the entire flight seems to be composed of this kind only–is the Aeschna bonariensis Raml, the prevailing colour of which is pale blue. But the really wonderful thing about them all alike is, that they appear only when flying before the southwest wind, called _pampero_–the wind that blows from the interior of the pampas. The pampero is a dry, cold wind, exceedingly violent. It bursts on the plains very suddenly, and usually lasts only a short time, sometimes not more than ten minutes; it comes irregularly, and at all seasons of the year, but is most frequent in the hot season, and after exceptionally sultry weather. It is in summer and autumn that the large dragon-flies appear; not _with_ the wind, but–and this is the most curious part of the matter–in advance of it; and inasmuch as these insects are not seen in the country at other times, and frequently appear in seasons of prolonged drought, when all the marshes and watercourses for many hundreds of miles are dry, they must of course traverse immense distances, flying before the wind at a speed of seventy or eighty miles an hour. On some occasions they appear almost simultaneously with the wind, going by like a flash, and instantly disappearing from sight. You have scarcely time to see them before the wind strikes you. As a rule, however, they make their appearance from five to fifteen minutes before the wind strikes; and when they are in great numbers the air, to a height of ten or twelve feet above the surface of the ground, is all at once seen to be full of them, rushing past with extraordinary velocity in a north-easterly direction. In very oppressive weather, and when the swiftly advancing pampero brings no moving mountains of mingled cloud and dust, and is consequently not expected, the sudden apparition of the dragon-fly is a most welcome one, for then an immediate burst of cold wind is confidently looked for. In the expressive vernacular of the gauchos the large dragon-fly is called _hijo del pampero_–son of the south-west wind.

It is clear that these great and frequent dragonfly movements are not explicable on any current hypothesis regarding the annual migrations of birds, the occasional migrations of butterflies, or the migrations of some mammals, like the reindeer and buffalo of Arctic America, which, according to Rae and other observers, perform long journeys north and south at regular seasons, “from a sense of polarity.” Neither this hypothetical sense in animals, nor “historical memory” will account for the dragon-fly storms, as the phenomenon of the pampas might be called, since the insects do not pass and repass between “breeding and subsistence areas,” but all journey in a north-easterly direction; and of the countless millions flying like thistledown before the great pampero wind, not one solitary traveller ever returns.

The cause of the flight is probably dynamical, affecting the insects with a sudden panic, and compelling them to rush away before the approaching tempest. The mystery is that they should fly from the wind before it reaches them, and yet travel in the same direction with it. When they pass over the level, treeless country, not one insect lags behind, or permits the wind to overtake it; but, on arriving at a wood or large plantation they swarm into it, as if seeking shelter from some swift-pursuing enemy, and on such occasions they sometimes remain clinging to the trees while the wind spends its force. This is particularly the case when the wind blows up at a late hour of the day; then, on the following morning, the dragon-flies are seen clustering to the foliage in such numbers that many trees are covered with them, a large tree often appearing as if hung with curtains of some brown glistening material, too thick to show the green leaves beneath.

In Patagonia, where the phenomenon of dragon-fly storms is also known, an Englishman residing at the Rio Negro related to me the following occurrence which he witnessed there. A race meeting was being held near the town of El Carmen, on a high exposed piece of ground, when, shortly before sunset, a violent pampero wind came up, laden with dense dust-clouds. A few moments before the storm broke, the air all at once became obscured with a prodigious cloud of dragon-flies. About a hundred men, most of them on horseback, were congregated on the course at the time, and the insects, instead of rushing by in their usual way, settled on the people in such quantities that men and horses were quickly covered with clinging masses of them. My informant said–and this agrees with my own observation–that he was greatly impressed by the appearance of terror shown by the insects; they clung to him as if for dear life, so that he had the greatest difficulty in ridding himself of them.

Weissenborn, in London’s _Magazine of Natural History_ (N. S. vol. iii.) describes a great migration of dragon-flies which he witnessed in Germany in 1839, and also mentions a similar phenomenon occurring in 1816, and extending over a large portion of Europe. But in these cases the movement took place at the end of May, and the insects travelled due south; their migrations were therefore similar to those of birds and butterflies, and were probably due to the same cause. I have been unable to find any mention of a phenomenon resembling the one with which we are so familiar on the pampas, and which, strangely enough, has not been recorded by any European naturalists who have travelled there.

CHAPTER X.

MOSQUITOES AND PARASITE PROBLEMS.

There cannot be a doubt that some animals possess an instinctive knowledge of their enemies–or, at all events, of some of their enemies–though I do not believe that this faculty is so common as many naturalists imagine. The most striking example I am acquainted with is seen in gnats or mosquitoes, and in the minute South American sandflies (Simulia), when a dragon-fly appears in a place where they are holding their aerial pastimes. The sudden appearance of a ghost among human revellers could not produce a greater panic. I have spoken in the last chapter of periodical storms or waves of dragon-flies in the Plata region, and mentioned incidentally that the appearance of these insects is most welcome in oppressively hot weather, since they are known to come just in advance of a rush of cool wind. In La Plata we also look for the dragon-fly, and rejoice at its coming, for another reason. We know that the presence of this noble insect will cause the clouds of stinging gnats and flies, which make life a burden, to vanish like smoke.

When a flight of dragon-flies passes over the country many remain along the route, as I have said, sheltering themselves wherever trees occur; and, after the storm blows over, these strangers and stragglers remain for some days hawking for prey in the neighbourhood. It is curious to note that they do not show any disposition to seek for watercourses. It may be that they feel lost in a strange region, or that the panic they have suffered, in their long flight before the wind, has unsettled their instincts; for it is certain that they do not, like the dragon-fly in Mrs. Browning’s poem, “return to dream upon the river.” They lead instead a kind of vagabond existence, hanging about the plantations, and roaming over the surrounding plains. It is then remarked that gnats and sand-flies apparently cease to exist, even in places where they have been most abundant. They have not been devoured by the dragon-flies, which are perhaps very few in number; they have simply got out of the way, and will remain in close concealment until their enemies take their departure, or have all been devoured by martins, tyrant birds, and the big robber-flies or devil’s dykes–no name is bad enough for them–of the family Asilidaa. During these peaceful gnatless days, if a person thrusts himself into the bushes or herbage in some dark sheltered place, he will soon begin to hear the thin familiar sounds, as of “horns of elf-land faintly blowing”; and presently, from the ground and the under surface of every leaf, the ghost-like withered little starvelings will appear in scores and in hundreds to settle on him, fear not having blunted their keen appetites.

When riding over the pampas on a hot still day, with a pertinacious cloud of gnats or sandflies hovering just above my head and keeping me company for miles, I have always devoutly wished for a stray dragon-fly to show himself. Frequently the wish has been fulfilled, the dragon-fly, apparently “sagacious of his quarry from afar,” sweeping straight at his prey, and instantly, as if by miracle, the stinging rain has ceased and the noxious cloud vanished from overhead, to be re-formed no more. This has always seemed very extraordinary to me; for in other matters gnats do not appear to possess even that proverbial small dose of intellect for which we give most insects credit. Before the advent of the dragon-fly it has perhaps happened that I have been vigorously striking at them, making it very unpleasant for them, and also killing and disabling many hundreds–a larger number than the most voracious dragon-fly could devour in the course of a whole day; and yet, after brushing and beating them off until my arms have ached with the exertion, they have continued to rush blindly on their fate, exhibiting not the faintest symptom of fear. I suppose that for centuries mosquitoes have, in this way, been brushed and beaten away with hands and with tails, without learning caution. It is not in their knowledge that there are hands and tails. A large animal is simply a field on which they confidently settle to feed, sounding shrill flourishes on their little trumpets to show how fearless they are. But the dragon-fly is very ancient on the earth, and if, during the Devonian epoch, when it existed, it preyed on some blood-sucking insect from which or Culicidae have come, then these stupid little insects have certainly had ample time in which to learn well at least one lesson.

There is not in all organic nature, to my mind, any instance of wasted energy comparable in magnitude with the mosquito’s thirst for blood, and the instincts and elaborate blood-pumping apparatus with which it is related. The amount of pollen given off by some wind-fertilized trees–so great in some places that it covers hundreds of square miles of earth and water with a film of yellow dust—strikes us as an amazing waste of material on the part of nature; but in these cases we readily see that this excessive prodigality is necessary to continue the species, and that a sufficient number of flowers would not be impregnated unless the entire trees were bathed for days in the fertilizing cloud, in which only one out of many millions of floating particles can ever hit the mark. The mosquito is able to procreate without ever satisfying its ravenous appetite for blood. To swell its grey thread-like abdomen to a coral bead is a delight to the insect, but not necessary to its existence, like food and water to ours; it is the great prize in the lottery of life, which few can ever succeed in drawing. In a hot summer, when one has ridden perhaps for half a day over a low-lying or wet district, through an atmosphere literally obscured with a fog of mosquitoes, this fact strikes the mind very forcibly, for in such places it frequently is the case that mammals do not exist, or are exceedingly rare. In Europe it is different. There, as Reaumur said, possibly one gnat in every hundred may be able to gratify its appetite for blood; but of the gnats in many districts in South America it would be nearer the mark to say that only one in a hundred millions can ever do so.

Curtis discovered that only the female mosquito bites or sucks blood, the male being without tongue or mandibles; and he asks, What, then, does the male feed on? He conjectures that it feeds on flowers; but, had he visited some swampy places in hot countries, where flowers are few and the insects more numerous than the sands on the seashore, he would most probably have said that the males subsist on decaying vegetable matter and moisture of slime. It is, however, more important to know what the female subsists on. We know that she thirsts for warm mammalian blood, that she seeks it with avidity, and is provided with an admirable organ for its extraction–only, unfortunately for her, she does not get it, or, at all events, the few happy individuals that do get it are swamped in the infinite multitude of those that are doomed by nature to total abstinence.

I should like to know whether this belief of Curtis, shared by Westwood and other distinguished entomologists, but originally put forward merely as a conjecture, has ever been tested by careful observation and experiment. If not, then it is strange that it should have crept into many important works, where it is stated not as a mere guess, but as an established fact. Thus, Van Beneden, in his work on parasites, while classing female mosquitoes with his “miserable wretches,” yet says, “If blood fails them, they live, like the males, on the juices of flowers.” If this be so, it is quite certain that the juices fail to satisfy them; and that, like Dr. Tanner, who was ravenously hungry during his forty days’ fast, in spite of his frequent sips of water, the mosquito still craves for something better than a cool vegetarian diet. I cannot help thinking, though the idea may seem fanciful, that mosquitoes feed on nothing. We know that the ephemerae take no refreshment in the imago state, the mouth being aborted or atrophied in these short-lived creatures; but we also know that they belong to an exceedingly ancient tribe, and possibly, after the earth had ceased to produce their proper nourishment there came in their history a long hungry period, which did not kill them, but lasted until their feeding instincts became obsolete, the mouth lost its use, and their life in its perfect state dwindled to its present length.

In any case, how unsatisfactory is the mosquitoes’ existence, and what a curious position they occupy in nature! Let us suppose that, owing to some great change in the conditions of the earth, rapacious birds were no longer able to capture prey, and that, by a corresponding change in their organizations, they were able to subsist on the air they breathed, with perhaps an occasional green leaf and a sip of water, and yet retained the old craving for solid food, and the old predatory instincts and powers undiminished; they would be in the position of mosquitoes in the imago state. And if then fifty or a hundred individuals were to succeed every year in capturing something and making one hearty meal, these few fortunate diners would bear about the same proportion to all the raptors on the globe as the mosquitoes that succeed in sucking blood to their unsuccessful fellows. In the case of the hawks, the effect of the few meals on the entire rapacious family or order would certainly be _nil;_ and it is impossible to believe for a moment that the comparatively infinitesimal amount of blood sucked by mosquitoes can. serve to invigorate the species. The wonder is that the machinery, which accomplishes nothing, should continue in such perfect working order.

When we consider the insect’s delicate organ, so admirably fitted for the purpose to which it is applied, it becomes difficult to believe that it could have been so perfected except in a condition of things utterly unlike the present. There must have been a time when mosquitoes found their proper nourishment, and when warm mammalian blood was as necessary to their existence as honey is to that of the bee, or insect food to the dragon-fly.

This applies to many blood-sucking insects besides mosquitoes, and with special force to the tick tribes (Ixodes), which swarm throughout Central and South America; for in these degraded spiders the whole body has been manifestly modified to fit it for a parasitical life; while the habits of the insect during its blind, helpless, waiting existence on trees, and its sudden great development when it succeeds in attaching itself to an animal body, also point irresistibly to the same conclusion. In the sunny uplands they act (writes Captain Burton) like the mosquitoes of the hot, humid Beiramar. “The nuisance is general; it seems to be in the air; every blade of grass has its colony; clusters of hundreds adhere to the twigs; myriads are found in the bush clumps. Lean and flat when growing to the leaves, the tick catches man or beast brushing by, fattens rapidly, and, at the end-of a week’s good living, drops off, _plena cruoris.”_ When on trees, Belt says, they instinctively place themselves on the extreme tips of leaves and shoots, with their hind legs stretching out, each foot armed with two hooks or claws, with which to lay hold of any animal brushing by. During this wretched, incom-plete existence (from which, in most cases, it is never destined to emerge), its greatest length is about one-fourth of an inch; but where it fastens itself to an animal the abdomen increases to a globe as big as a medium-sized Barcelona nut. Being silvery-grey or white in colour, it becomes, when thus distended, very conspicuous on any dark surface. I have frequently seen black, smooth-haired dogs with their coats, turned into a perfect garden of these white spider-flowers or mushrooms. The white globe is leathery, and nothing can injure it; and the poor beast cannot rub, bite, or scratch it off, as it is anchored to his flesh by eight sets of hooks and a triangle of teeth.

The ticks inhabiting regions rich in bird and insect life, but with few mammals, are in the same condition as mosquitoes, as far as the supply of blood goes; and, like the mosquitoes, they are compelled and able to exist without the nourishment best suited to them. They are nature’s miserable castaways, parasitical tribes lost in a great dry wilderness where no blood is; and every marsh-born mosquito, piping of the hunger gnawing its vitals, and every forest tick, blindly feeling with its grappling-irons for the beast that never brushes by, seems to tell us of a world peopled with gigantic forms, mammalian and reptilian, which once afforded abundant pasture to the parasite, and which the parasite perhaps assisted to overthrow.

It is almost necessary to transport oneself to the vast tick-infested wilderness of the New World to appreciate the full significance of a passage in Belt’s _Naturalist in Nicaragua,_ in which it is suggested that man’s hairless condition was perhaps brought about by natural selection in tropical regions, where he was greatly troubled with parasites of this kind. It is certain that if in such a country as Brazil he possessed a hairy coat, affording cover to the tick and enabling it to get a footing on the body, his condition would be a very sad one. Savages abhor hairs on the body, and even pluck them off their faces. This seems like a survival of an ancient habit acquired when the whole body was clothed with hair; and if primitive man ever possessed such a habit, nature only followed his lead in giving him a hairless offspring.

Is it not also probable that the small amount of mammalian life in South America, and the aquatic habits of nearly all the large animals in the warmer districts, is due to the persecutions of the tick?

The only way in which a large animal can rid itself of the pest is by going into the water or wallowing in the mud; and this perhaps accounts for the more or less aquatic habits of the jaguar, aguara-guazu, the large Cervus paluclosus, tapir, capybara, and peccary. Monkeys, which are most abundant, are a notable exception; but these animals have the habit of attending to each other’s skins, and spend a great deal of their time in picking off the parasites. But how do birds escape the ticks, since these parasites do not confine their attacks to any one class of aninials, but attach themselves impartially to any living thing coming within reach of their hooks, from snake to man? My own observations bearing on this point refer less to the Ixodes than to the minute bete-rouge, which is excessively abundant in the Plata district, where it is known as _bicho colorado,_ and in size and habits resembles the English Leptus autumnalis. It is so small that, notwithstanding its bright scarlet colour, it can only be discerned by bringing the eye close to it; and being, moreover, exceedingly active and abundant in all shady places in summer–making life a misery to careless human beings–it must be very much more dangerous to birds than the larger sedentary Ixodes. The bete-rouge invariably lodges beneath the wings of birds, where the loose scanty plumage affords easy access to the skin. Domestic birds suffer a great deal from its persecutions, and their. young, if allowed to run about in shady places, die of the irritation. Wild birds, however, seem to be very little troubled, and most of those I have examined have been almost entirely free from parasites. Probably they are much more sensitive than the domestic birds, and able to feel and pick off the insects with their beaks before they have penetrated into the skin. I believe they are also able to protect themselves in another way, namely, by preventing the parasites from reaching their bodies at all. I was out under the trees one day with a pet oven-bird (Furnarius rufus), which had full liberty to range about at will, and noticed that at short intervals it went through the motions of picking something from its toes or legs, though I could see nothing on them. At length I approached my eyes to within a few inches of the bird’s feet, and discovered that the large dry branch on which it stood was covered with a multitude of parasites, all running rapidly about like foraging ants, and whenever one came to the bird’s feet it at once ran up the leg. Every time this happened, so far as I could see, the bird felt it. and quickly and deftly picked it off with the point of its bill. It seemed very astonishing that the horny covering of the toes and legs should be so exquisitely sensitive, for the insects are so small and light that they cannot be felt on the hand, even when a score of them are running over it; but the fact is as I have stated, and it is highly probable, I think, that most wild birds keep themselves free from these little torments in the same way.

Some observations of mine on a species of Orni-thomyia–a fly parasitical on birds–might possibly be of use in considering the question of the anomalous position in nature of insects possessing the instincts and aptitudes of parasites, and organs manifestly modified to suit a parasitical mode of life, yet compelled and able to exist free, feeding, perhaps, on vegetable juices, or, like the ephemerae, on nothing at all. For it must be borne in mind that I do not assert that these “occasional” or “accidental” parasites, as some one calls them, explaining nothing, do not feed on such juices. I do not know what they feed on. I only know that the joyful alacrity with which gnats and stinging flies of all kinds abandon the leaves, supposed to afford them pasture, to attack a warm-blooded animal, serves to show how strong the impulse is, and how ineradicable the instinct, which must have had an origin. Perhaps the habits of the bird-fly I have mentioned will serve to show how, in some cases, the free life of some blood-sucking flies and other insects might have originated.

Kirby and Spence, in their _Introduction,_ mention that one or two species of Ornithomyia have been observed flying about and alighting on men; and in one case the fly extracted blood and was caught, the species being thus placed beyond doubt. This circumstance led the authors to believe that the insect, when the bird it is parasitical on dies, takes to flight and migrates from body to body, occasionally tasting blood until, coming to the right body–to wit, that of a bird, or of a particular species of bird–it once more establishes itself permanently in the plumage. I fancy that the insect sometimes leads a freer life and ranges much more than the authors imagined; and I refer to Kirby and Spence, with apologies to those who regard the _Introduction_ as out of date, only because I am not aware that we have any later observations on the subject.

There is in La Plata a small very common Dendrocolaptine bird–Anumbius acuticaudatus–much infested by an Ornithomyia, a pretty, pale insect, half the size of a house-fly, and elegantly striped with green. It is a very large parasite for so small a bird, yet so cunning and alert is it, and so swiftly is it able to swim through the plumage, that the bird is unable to rid itself of so undesirable a companion. The bird lives with its mate all the year round, much of the time with its grown-up young, in its nest–a large structure, in which so much building-material is used that the bird is called in the vernacular Lenatero, or Firewood-gatherer. On warm bright days without wind, during the absence of the birds, I have frequently seen a company of from half a dozen to a dozen or fifteen of the parasitical fly wheeling about in the air above the nest, hovering and gambolling together, just like house-flies in a room in summer; but always on the appearance of the birds, returning from their feeding-ground, they would instantly drop down and disappear into the nest. How curious this instinct seems! The fly regards the bird, which affords it the warmth and food essential to life, as its only deadly enemy; and with an inherited wisdom, like that of the mosquito with regard to the dragon-fly, or of the horse-fly with regard to the Monedula wasp, vanishes like smoke from its presence, and only approaches the bird secretly from a place of concealment.

The parasitical habit tends inevitably to degrade the species acquiring it, dulling its senses and faculties, especially those of sight and locomotion; but the Ornithomyia seems an exception, its dependent life having had a contrary effect; the extreme sensitiveness, keenness of sight, and quickness of the bird having reacted on the insect, giving it a subtlety in its habits and motions almost without a parallel even among free insects. A man with a blood-sucking flat-bodied flying squirrel, concealing itself among his clothing and gliding and dodging all over his body with so much artifice and rapidity as to defeat all efforts made to capturo it or knock it off, would be a case parallel to that of the bird-fly on the small bird. It might be supposed that the Firewood-gatherer, like some ants that keep domestic pets, makes a pet of the fly; for it is a very pretty insect, barred with green, and with rainbow reflections on its wings–and birds are believed by some theorists to possess aesthetic tastes; but the discomfort of having such a vampire on the body would, I imagine, be too great to allow a kindly instinct of that nature to grow up. Moreover, I have on several occasions seen the bird making frantic efforts to capture one of the flies, which had incautiously flown up from the nest at the wrong moment. Bird and fly seem to know each other wonderfully well.

Here, then, we have a parasitical insect specialized in the highest degree, yet retaining all its pristine faculties unimpaired, its love of liberty, and of associating in numbers together for sportive exercises, and well able to take care of itself during its free intervals. And probably when thrown on the world, as when nests are blown down, or the birds get killed, or change their quarters, as they often do, it is able to exist for some time without avian blood. Let us then imagine some of these orphaned colonies, unable to find birds, but through a slight change in habits or organization able to exist in the imago state without sucking blood until they laid their eggs; and succeeding generations, still better able to stand the altered conditions of life until they become practically independent (like gnats), multiplying greatly, and disporting themselves in clouds over forests, yet still retaining the old hunger for blood and the power to draw it, and ready at any moment to return to the ancestral habit. It might be said that if such a result were possible it would have occurred, but that we find no insect like the Ornithomyia existing independently. With the bird-fly it has not occurred, as far as we know; but in the past history of some independent parasites it is possible that something similar to the imaginary case I have sketched may have taken place. The bush-tick is a more highly specialized, certainly a more degraded, creature than the bird-fly, and the very fact of its existence seems to show that it is possible for even the lowest of the fallen race of parasites to start afresh in life under new conditions, and to reascend in the scale of being, although still bearing about it the marks of former degeneracy.

The connection between the flea and the mammal it feeds on is even less close than that which exists between the Ornithomyia and bird. The fact that fleas are so common and universal–for in all lands we have them, like the poor, always with us; and that they are found on all mammals, from the king of beasts to the small modest mouse–seems to show a great amount of variability and adaptiveness, as well as a very high antiquity. It has often been reported that fleas have been found hopping on the ground in desert places, where they could not have been dropped by man or beast; and it has been assumed that these “independent” fleas must, like gnats and ticks, subsist on vegetable juices. There is no doubt that they are able to exist and propagate for one or two years after being deprived of their proper aliment; houses shut up for a year or longer are sometimes found infested with them; possibly in the absence of “vegetable juices” they flourish on dust. I have never detected them hopping on the ground in uninhabited places, although I once found them in Patagonia, in a hamlet which had been attacked and depopulated by the Indians about twenty months before my visit. On entering one of the deserted huts I found the floor literally swarming with fleas, and in less than ten seconds my legs, to the height of my knees, were almost black with their numbers. This proves that they are able toincrease greatly for a period without blood; but I doubt that they can go on existing and increasing for an indefinite time; perhaps their true position, with regard to the parasitical habit, is midway between that of the strict parasite which never leaves the body, and that of independent parasites like the Culex and the Ixodes, and all those which are able to exist free for ever, and are parasitical only when the opportunity offers.

Entomologists regard the flea as a degraded fly. Certainly it is very much more degraded than the bird-borne Ornithomyia, with its subtle motions and instinct, its power of flight and social pastimes. The poor pulex has lost every trace of wings; nevertheless, in its fallen condition it has developed some remarkable qualities and saltatory powers, which give it a lower kind of glory; and, compared with another parasite with which it shares the human species, it is almost a noble insect. Darwin has some remarks about the smallness of the brain of an ant, assuming that this insect possesses a very high intelligence, but I doubt very much that the ant, which moves in a groove, is mentally the superior of the unsocial flea. The last is certainly the most teachable; and if fleas were generally domesticated and made pets of, probably there would be as many stories about their marvellous intelligence and fidelity to man as we now hear about our over-praised “friend” the dog.

With regard to size, the flea probably started on its downward course as a comparatively large insect, probably larger than the Ornithomyia. That insect has been able to maintain its existence, without dwindling like the Leptus into a mere speck, through the great modification in organs and instinct, which adapt it so beautifully to the feathery element in which it moves. The bush-tick, wingless from the beginning, and diverging in another direction, has probably been greatly increased in size by its parasitical habit; this seems proven by the fact, that as long as it is parasitical on nothing it remains small, but when able to fasten itself to an animal it rapidly developes to a great size. Again, the big globe of its abdomen is coriaceous and elastic, and is probably as devoid of sensation as a ball of india-rubber. The insect, being made fast by hooks and teeth to its victim, all efforts to remove it only increase the pain it causes; and animals that know it well do not attempt to rub, scratch, or bite it off, therefore the great size and the conspicuous colour of the tick are positive advantages to it. The flea, without the subtlety and highly-specialized organs of the Ornithomyia, or the stick-fast powers and leathery body of the Ixodes, can only escape its vigilant enemies by making itself invisible; hence every variation, i.e. increase in jumping-power and diminished bulk, tending towards this result, has been taken advantage of by natural selection.

CHAPTER XI

HUMBLE-BEES AND OTHER MATTERS.

Two humble-bees, Bombus thoracicus and B. violaceus, are found on the pampas; the first, with a primrose yellow thorax, and the extremity of the abdomen bright rufous, slightly resembles the English B. terrestris; the rarer species, which is a trifle smaller than the first, is of a uniform intense black, the body having the appearance of velvet, the wings being of a deep violaceous blue.

A census of the humble-bees in any garden or field always shows that the yellow bees outnumber the black in the proportion of about seven to one; and I have also found their nests for many years in the same proportion; about seven nests of the yellow to one nest of the black species. In habits they are almost identical, and when two species so closely allied are found inhabiting the same locality, it is only reasonable to infer that one possesses some advantage over the other, and that the least favoured species will eventually disappear. In this case, where one so greatly outnumbers the other, it might be thought that the rarer species is dying out, or that, on the contrary, it is a new-comer destined to supplant the older more numerous species. Yet, during the twenty years I have observed them, there has occurred no change in their relative positions; though both have greatly increased in numbers during that time, owing to the spread of cultivation. And yet it would scarcely be too much to expect some marked change in a period so long as that, even through the slow-working agency of natural selection; for it is not as if there had been an exact balance of power between them. In the same period of time I have seen several species, once common, almost or quite disappear, while others, very low down as to numbers, have been exalted to the first rank. In insect life especially, these changes have been numerous, rapid, and widespread.

In the district where, as a boy, I chased and caught tinamous, and also chased ostriches, but failed to catch them, the continued presence of our two humble-bees, sucking the same flowers and making their nests in the same situations, has remained a puzzle to my mind.

The site of the nest is usually a slight depression in the soil in the shelter of a cardoon bush. The bees deepen the hollow by burrowing in the earth; and when the spring foliage sheltering it withers up, they construct a dome-shaped covering of small sticks, thorns, and leaves bitten into extremely minute pieces. They sometimes take possession of a small hole or cavity in the ground, and save themselves the labour of excavation.

Their architecture closely resembles that of B. terrestris. They make rudely-shaped oval honey-cells, varying from half an inch to an inch and a half in length, the smaller ones being the first made; later in the season the old cocoons are utilized for storing honey. The wax is chocolate-coloured, and almost the only difference I can find in the economy of the two species is that the black bee uses a large quantity of wax in plastering the interior of its nest. The egg-cell of the yellow bee always contains from twelve to sixteen eggs; that of the black bee from ten to fourteen; and the eggs of this species are the largest though the bee is smallest. At the entrance on the edge of the mound one bee is usually stationed, and, when approached, it hums a shrill challenge, and throws itself into a menacing attitude. The sting is exceedingly painful.

One summer I was so fortunate as to discover two nests of the two kinds within twelve yards of each other, and I resolved to watch them very carefully, in order to see whether the two species ever came into collision, as sometimes happens with ants of different species living close together. Several times I saw a yellow bee leave its own nest and hover round or settle on the neighbouring one, upon which the sentinel black bee would attack and drive it off. One day, while watching, I was delighted to see a yellow bee actually enter its neighbour’s nest, the sentinel being off duty. In about five minutes’ time it came out again and flew away unmolested. I concluded from this that humble-bees, like their relations of the hive, occasionally plunder each other’s sweets. On another occasion I found a black bee dead at the entrance of the yellow bees’ nest; doubtless this individual had been caught in the act of stealing honey, and, after it had been stung to death, it had been dragged out and left there as a warning to others with like felonious intentions.

There is one striking difference between the two species. The yellow bee is inodorous; the black bee, when angry and attacking, emits an exceedingly powerful odour: curiously enough, this smell is identical in character with that made when angry by all the wasps of the South American genus Pepris–dark blue wasps with red wings. This odour at first produces a stinging sensation on the nerve of smell, but when inhaled in large measure becomes very nauseating. On one occasion, while I was opening a nest, several of the bees buzzing round my head and thrusting their stings through the veil I wore for protection, gave out so pungent a smell that I found it unendurable, and was compelled to retreat.

It seems strange that a species armed with a venomous sting and possessing the fierce courage of the humble-bee should also have this repulsive odour for a protection. It is, in fact, as incongruous as it would be were our soldiers provided with guns and swords first, and after with phials of assafoatida to be uncorked in the face of an enemy.

Why, or how, animals came to be possessed of the power of emitting pestiferous odours is a mystery; we only see that natural selection has, in some mstances, chiefly among insects, taken advantage of it to furnish some of the weaker, more unprotected species with a means of escape from their enemies. The most stinking example I know is that of a large hairy caterpillar I have found on dry wood in Patagonia, and which, when touched, emits an intensely nauseous effluvium. Happily it is very volatile, but while it lasts it is even more detestable than that of the skunk.

The skunk itself offers perhaps the one instance amongst the higher vertebrates of an animal in which all the original instincts of self-preservation have died out, giving place to this lower kind of protection. All the other members of the family it belongs to are cunning, swift of foot, and, when overtaken, fierce-tempered and well able to defend themselves with their powerful well-armed jaws.

For some occult reason they are provided with a gland charged with a malodorous secretion; and out of this mysterious liquor Nature has elaborated the skunk’s inglorious weapon. The skunk alone when attacked makes no attempt to escape or to defend itself by biting; but, thrown by its agitation into a violent convulsion, involuntarily discharges its foetid liquor into the face of an opponent. When this animal had once ceased to use so good a weapon as its teeth in defending itself, degenerating at the same time into a slow-moving creature, without fear and without cunning, the strength and vileness of its odour would be continually increased by the cumulative process of natural selection: and how effective the protection has become is shown by the abundance of the species throughout the whole American continent. It is lucky for mankind–especially for naturalists and sportsmen–that other species have not been improved in the same direction.

But what can we say of the common deer of the pampas (Cervus campestris), the male of which gives out an effluvium quite as far-reaching although not so abominable in character as that of the Mephitis? It comes in disagreeable whiffs to the human nostril when the perfumer of the wilderness is not even in sight. Yet it is not a protection; on the contrary, it is the reverse, and, like the dazzling white plumage so attractive to birds of prey, a direct disadvantage, informing all enemies for leagues around of its whereabouts. It is not, therefore, strange that wherever pumas are found, deer are never very abundant; the only wonder is that, like the ancient horse of America, they have not become extinct.

The gauchos of the pampas, however, give _a reason_ for the powerful smell of the male deer; and, after some hesitation, I have determined to set it down here, for the reader to accept or reject, as he thinks proper. I neither believe nor disbelieve it; for although I do not put great faith in gaucho natural history, my own observations have not infrequently confirmed statements of theirs, which a sceptical person would have regarded as wild indeed. To give one instance: I heard a gaucho relate that while out riding he had been pursued for a considerable distance by a large spider; his hearers laughed at him for a romancer; but as I myself had been attacked and pursued, both when on foot and on horseback, by a large wolf-spider, common on the pampas, I did not join in the laugh. They say that the effluvium of C. campestris is abhorrent to snakes of all kinds, just as pyrethrum powder is to most insects, and even go so far as to describe its effect as fatal to them; according to this, the smell is therefore a protection to the deer. In places where venomous snakes are extremely abundant, as in the Sierra district on the southern pampas of Buenos Ayres, the gaucho frequently ties a strip of the male deer’s skin, which retains its powerful odour for an indefinite time, round the neck of a valuable horse as a protection. It is certain that domestic animals are frequently lost here through snake-bites. The most common poisonous species–the Craspedo-cephalus alternatus, called _Vivora de la Cruz_ in the vernacular–has neither bright colour nor warning rattle to keep off heavy hoofs, and is moreover of so sluggish a temperament that it will allow itself to be trodden on before stirring, with the result that its fangs are not infrequently struck into the nose or foot of browsing beast. Considering, then, the conditions in which C. campestris is placed–and it might also be supposed that venomous snakes have in past times been much more numerous than they are now–it is not impossible to believe that the powerful smell it emits has been made protective, especially when we see in other species how repulsive odours have been turned to account by the principle of natural selection.

After all, perhaps the wild naturalist of the pampas knows what he is about when he ties a strip of deer-skin to the neck of his steed and turns him loose to graze among the snakes.

The gaucho also affirms that the deer cherishes a wonderful animosity against snakes; that it becomes greatly excited when it sees one, and proceeds at once to destroy it; _they say,_ by running round and round it in a circle, emitting its violent smell in larger measure, until the snake dies of suffocation. It is hard to believe that the effect can be so great; but that the deer is a snake hater and killer is certainly true: in North America, Ceylon, and other districts deer have been observed excitedly leaping on serpents, and killing them with their sharp cutting hoofs.

CHAPTER XII.

A NOBLE WASP.

_(Monedula punctata.)_

Naturalists, like kings and emperors, have their favourites, and as my zoological sympathies, which are wider than my knowledge, embrace all classes of beings, there are of course several insects for which I have a special regard; a few in each of the principal orders. My chief favourite among the hymenopteras is the one representative of the curious genus Monedula known in La Plata. It is handsome and has original habits, but it is specially interesting to me for another reason: I can remember the time when it was extremely rare on the pampas, so rare that in boyhood the sight of one used to be a great event to me; and I have watched its rapid increase year by year till it has come to be one of our commonest species. Its singular habits and intelligence give it a still better claim to notice. It is a big, showy, loud-buzzing insect, with pink head and legs, wings with brown reflections, and body encircled with alternate bands of black and pale gold, and has a preference for large composite flowers, on the honey of which it feeds. Its young is, however, an insect-eater; but the Monedula does not, like other burrowing or sand wasps, put away a store of insects or spiders, partially paralyzed, as a provision for the grub till it reaches the pupa state; it actually supplies the grub with fresh-caught insects as long as food is required, killing the prey it captures outright, and bringing it in to its young; so that its habits, in this particular, are more bird- than wasp-like.

The wasp lays its solitary egg at the extremity of a hole it excavates for itself on a bare hard piece of ground, and many holes are usually found close together. When the grub–for I have never been able to find more than one in a hole–has come out from the egg, the parent begins to bring in insects, carefully filling up the mouth of the hole with loose earth after every visit. Without this precaution, which entails a vast amount of labour, I do not believe one grub out of every fifty would survive, so overrun are these barren spots of ground used as breeding-places with hunting spiders, ants, and tiger-beetles. The grub is a voracious eater, but the diligent mother brings in as much as it can devour. I have often found as many as six or seven insects, apparently fresh killed, and not yet touched by the pampered little glutton, coiled up in the midst of them waiting for an appetite.

The Monedula is an adroit fly-catcher, for though it kills numbers of fire-flies and other insects, flies are always preferred, possibly because they are so little encumbered with wings, and are also more easily devoured. It occasionally captures insects on the wing, but the more usual method is to pounce down on its prey when it is at rest. At one time, before I had learnt their habits, I used frequently to be startled by two or three or more of these wasps rushing towards my face, and continuing hovering before it, loudly buzzing, attending me in my walks about the fields. The reason of this curious proceeding is that the Monedula preys largely on stinging flies, having learnt from experience that the stinging fly will generally neglect its own safety when it has once fastened on a good spot to draw blood from. When a man or horse stands perfectly motionless the wasps take no notice, but the moment any movement is made of hand, tail, or stamping hoof, they rush to the rescue, expecting to find a stinging fly. On the other hand, the horse has learnt to know and value this fly-scourge, and will stand very quietly with half a dozen loud Avasps hovering in an alarming manner close to his head, well knowing that every fly that settles on him will be instantly snatched away, and that the boisterous Monedula is a better protection even than the tail–which, by the way, the horse wears very long in Buenos Ayres.

I have, in conclusion, to relate an incident I onco witnessed, and which does not show the Monedula in a very amiable light. I was leaning over a gate watching one of these wasps feeding on a sunflower. A small leaf-cutting bee was hurrying about with its shrill busy hum in the vicinity, and in due time came to the sunflower and settled on it. The Monedula became irritated, possibly at the shrill voice and bustling manner of its neighbour, and, after watching it for a few moments on the flower, deliberately rushed at and drove it off. The leaf-cutter quickly returned, however–for bees are always extremely averse to leaving a flower unexplored–but was again driven away with threats and demonstrations on the part of the Monedula. The little thing went off and sunned itself on a leaf for a time, then returned to the flower, only to be instantly ejected again. Other attempts were made, but the big wasp now kept a jealous watch on its neighbour’s movements, and would not allow it to come within several inches of the flower without throwing itself into a threatening attitude. The defeated bee retired to sun itself once more, apparently determined to wait for the big tyrant to go away; but the other seemed to know what was wanted, and spitefully made up its mind to stay where it was. The leaf-cutter then gave up the contest. Suddenly rising up into the air, it hovered, hawk-like, above the Monedula for a moment, then pounced down on its back, and clung there, furiously biting, until its animosity was thoroughly appeased; then it flew off, leaving the other master of the field certainly, but greatly discomposed, and perhaps seriously injured about the base of the wings. I was rather surprised that they were not cut quite off, for a leaf-cutting bee can use its teeth as deftly as a tailor can his shears.

Doubtless to bees, as to men, revenge is sweeter than honey. But, in the face of mental science, can a creature as low down in the scale of organization as a leaf-cutting bee be credited with anything so intelligent and emotional as deliberate anger and revenge, “which implies the need of retaliation to satisfy the feelings of the person (or bee) offended?” According to Bain _(Mental and Moral Science)_ only the highest animals–stags and bulls he mentions-can be credited with the developed form of anger, which, he describes as an excitement caused by pain, reaching the centres of activity, and containing an impulse knowingly to inflict suffering on another sentient being. Here, if man only is meant, the spark is perhaps accounted for, but not the barrel of gunpowder. The explosive material is, however, found in the breast of nearly every living creature. The bull–ranking high according to Bain, though I myself should place him nearly on a level mentally with the majority of the lower animals, both vertebrate and insect–is capable of a wrath exceeding that of Achilles; and yet the fact that a red rag can manifestly have no associations, personal or political, for the bull, shows how uniutcllectual his anger must be. Another instance of misdirected anger in nature, not quite so familiar .as that of the bull and red rag, is used as an illustration by one of the prophets: “My heritage is unto me as a speckled bird; the birds round, about are against it.” I have frequently seen the birds of a thicket gather round some singularly marked accidental visitor, and finally drive him with great anger from the neighbourhood. Possibly association comes in a little here, since any bird, even a small one, strikingly coloured or