Argentine Ornithology Volume Ii Part 16

Though an inordinate lover of carrion, a wise instinct has taught it that this aliment is unsuited to the tender stomachs of its fledglings; these it feeds almost exclusively on the young of small birds. In November the Chimangos are seen incessantly beating over the cardoon bushes, after the manner of Hen-harriers; for at this season in the cardoons breeds the _Synallaxis hudsoni_. This bird, sometimes called _Teru-reru del campo_ by the natives, is excessively shy and mouse-like in its habits, seldom showing itself, and by means of strong legs and a long, slender, wedge-like body is able too glide swiftly as a snake through and under the gra.s.s. In summer one hears its long melancholy trilling call-note from a cardoon bush, but if approached it drops to the ground and vanishes. Under the densest part of the cardoon bush it scoops out a little circular hollow in the soil, and constructs over it a dome of woven gra.s.s and thorns, leaving only a very small aperture: it lines the floor with dry horse-dung, and lays five buff-coloured eggs.

So admirably is the nest concealed that I have searched every day for it through a whole breeding-season without being rewarded with a single find. Yet they are easily found by the Chimango. In the course of a single day I have examined five or six broods of young Chimangos, and by pressing a finger in their distended crops, made them disgorge their food, and found in every instance that they had been fed on nothing but the young of the _Teru-reru_. I was simply amazed at this wholesale destruction of the young of a species so secret in its nesting-habits; for no eye, even of a Hawk, can pierce through the leaf.a.ge of a cardoon bush, ending near the surface in an acc.u.mulated ma.s.s of the dead and decaying portions of the plant. The explanation of the Chimango's success is to be found in the loquacious habit of the fledglings it preys on, a habit common in the young of Dendrocolaptine species. The intervals between the visits of the parent birds with food they spend in conversing together in their high-pitched tones. If a person approaches the solid fabric of the Ovenbird (_Furnarius rufus_), when there are young in it, he will hear shrill laughter-like notes and little choruses, like those uttered by the old birds, only feebler; but in the case of that species no harm can result from the loquacity of the young, since the castle they inhabit is impregnable. Hovering over the cardoons, the Chimango listens for the stridulous laughter of the fledglings, and when he hears it the th.o.r.n.y covering is quickly pierced and the dome broken into.

Facts like this bring before us with startling vividness the struggle for existence, showing what great issues in the life of a species may depend on matters so trivial, seemingly, that to the uninformed mind they appear like the merest dust in the balance, which is not regarded.

And how tremendous and pitiless is that searching law of the survival of the fittest in its operations when we see a species like this _Synallaxis_, in the fashioning and perfecting of which nature seems to have exhausted all her art, so exquisitely is it adapted in its structure, coloration, and habits to the one great object of concealment, yet apparently doomed to destruction through this one petty oversight--the irrepressible garrulity of the fledglings in their nest!

It is, however, no oversight at all; since the law of natural selection is not prophetic in its action, and only preserves such variations as are beneficial in existing circ.u.mstances, without antic.i.p.ating changes in the conditions. The settlement of the country has, no doubt, caused a great increase of Chimangos, and in some indirect way probably has served to quicken their intelligence; thus a change in the conditions which have moulded this _Synallaxis_ brings a danger to it from an unexpected quarter. The situation of the nest exposes it, one would imagine, to attacks from snakes and small mammals, from bird-killing spiders, beetles, and crickets, yet these subtle ground foes have missed it, while the baby-laughter of the little ones in their cradle has called down an unlooked-for destroyer from above. It might be answered that this must be a very numerous species, otherwise the Chimango could not have acquired the habit of finding the nests; that when they become rarer the pursuit will be given over, after which the balance will readjust itself. But in numbers there is safety, especially for a feeble hunted species, unable from its peculiar structure to vary its manner of life. To such, the remark made by Darwin, that "rarity is the precursor to extinction," applies with peculiar force.

310. POLYBORUS THARUS (Mol.).

(CARANCHO CARRION-HAWK.)

+Polyborus vulgaris+, _Burm. La-Plata Reise_, ii. p. 434 (La Plata); _Durnford, Ibis_, 1877, p. 40 (Chupat). +Polyborus tharus+, _Scl.

et Salv. Nomencl._ p. 123; _Durnford, Ibis_, 1877, p. 188 (Buenos Ayres), et 1878, p. 398 (Centr. Patagonia); _Gibson, Ibis_, 1879, p. 415 (Buenos Ayres); _White, P. Z. S._ 1883, p. 41 (Cordova); _Barrows, Auk_, 1884, p. 111 (Entrerios); _Sharpe, Cat. B._ i. p.

31. +Polyborus brasiliensis+, _Darwin, Zool. Beagle_, iii. p. 9.

_Description._--Above dark brown with whitish mottlings; head blackish; wings and tail greyish white, with numerous greyish-brown cross bars and blackish tips: beneath dark brown, varied with white; throat and sides of head fulvous white; bill yellow, bluish at the base; cere orange; feet brown; claws black: whole length 20 inches, wing 155, tail 90. _Female_ similar.

_Hab._ South America.

This bird, which combines the raptorial instincts of the Eagle with the base carrion-feeding propensities of the Vulture, has already had so many biographers that it might seem superfluous to speak again at any great length of it; only it happens to be one of those very versatile species about which there is always something fresh to be said; and, besides, I do not altogether agree with the very ign.o.ble character usually ascribed to it by travellers. It is, however, probable that it varies greatly in disposition and habits in different districts. In Patagonia I was surprised at its dejected appearance and skulking cowardly manner, so unlike the bird I had been accustomed to see on the pampas. I shot several, and they were all in a miserably poor condition and apparently half-starved. It struck me that in that cold sterile country, where prey is scarce, the Carancho is altogether out of place; for it there has to compete with Eagles and Vultures in large numbers; and these, it is almost needless to say, are, in their separate lines, stronger than the composite and less specialized Carancho. In Patagonia he is truly a "miserable bird," with a very frail hold on existence. How different on that illimitable gra.s.sy ocean further north, where he is the lord of the feathered race, for Eagles and Vultures, that require mountains and trees to breed and roost on, do not come there to set him aside; there the conditions are suited to him and have served to develop in him a wonderfully bold and savage spirit. When seen perched on a conical ant-hill, standing erect above the tall plumy gra.s.s, he has a fine, even a n.o.ble, appearance; but when flying he is not handsome, the wings being very bluntly rounded at the extremities and the flight low and ungraceful. The plumage is blackish in the adult, brown in the young. The sides of the head and breast are creamy white, the latter transversely marked with black spots. The crown is adorned with a crest or top-knot. The beak is much larger than in Eagles and Vultures, and of a dull blue colour; the cere and legs are bright yellow.

The species ranges throughout South America, and from Paraguay northwards is called everywhere, I believe, "Caracara." South of Paraguay the Spanish name is "Carancho," possibly a corruption of "Keanche," the Puelche name for the allied _Milvago chimango_, in imitation of its peevish cry. The Indian name for the Carancho in these regions is _Traru_ (from its harsh cry), misspelt _tharu_ by Molina.

The Caranchos pair for life, and may therefore be called social birds; they also often live and hunt in families of the parent and young birds until the following spring; and at all times several individuals will readily combine to attack their prey, but they never live or move about in flocks. Each couple has its own home or resting-place, which they will continue to use for an indefinite time, roosting on the same branch and occupying the same nest year after year; while at all times the two birds are seen constantly together and seem very much attached. Azara relates that he once saw a male pounce down on a frog, and carrying it to a tree call his mate to him and make her a present of it. It was not a very magnificent present, but the action seems to show that the bird possesses some commendable qualities which are seldom seen in the raptorial family.

In uninhabited places I have always found the Caranchos just as abundant as in the settled districts; and after a deer has been pulled down by the dogs I have seen as many as seventy or eighty birds congregate to feed on its flesh within half an hour, although not one had been previously visible. D'Orbigny describes the bird as a parasite on man, savage and civilized, following him everywhere to feed on the leavings when he slays wild or domestic animals, and as being scarcely able to exist without him. No doubt the bird does follow man greatly to its advantage, but this is only in very thinly settled and purely pastoral and hunting districts, where a large proportion of the flesh of every animal slain is given to the fowls of the air. Where the population increases the Carancho quickly meets with the fate of all large species which are regarded as prejudicial.

Without doubt it is a carrion-eater, but only, I believe, when it cannot get fresh provisions; for when famished it will eat anything rather than study its dignity and suffer hunger like the n.o.bler Eagle. I have frequently seen one or two or three of them together on the ground under a column of winged ants, eagerly feasting on the falling insects. To eat putrid meat it must be very hungry indeed; it is, however, amazingly fond of freshly-killed flesh, and when a cow is slaughtered at an estancia-house the Carancho quickly appears on the scene to claim his share, and catching up the first thing he can lift he carries it off before the dogs can deprive him of it. When he has risen to a height of five or six yards in the air he drops the meat from his beak and dexterously catches it in his claws without pausing or swerving in his flight. It is singular that the bird seems quite incapable of lifting anything from the ground with the claws, the beak being invariably used, even when the prey is an animal which it might seem dangerous to lift in this way. I once saw one of these birds swoop down on a rat from a distance of about forty feet, and rise with its struggling and squealing prey to a height of twenty feet, then drop it from its beak and gracefully catch it in its talons. Yet when it pursues and overtakes a bird in the air it invariably uses the claws in the same way as other Hawks. This I have frequently observed, and I give the two following anecdotes to show that even birds which one would imagine to be quite safe from the Carancho are on some occasions attacked by it.

While walking in a waste field near my home one day I came on a Pigeon feeding, and at once recognized it as one which had only began to fly about a week before; for although a large number of Pigeons were kept, this bird happened to be of the purest unspotted white, and for a long time I had been endeavouring to preserve and increase the pure white individuals, but with very little success, for the Peregrines invariably singled them out for attack. A Carancho was circling about at some distance overhead, and while I stood still to watch and admire my Pigeon it stooped to within twenty yards of the surface and remained hovering over my head. Presently the Pigeon became alarmed and flew away, whereupon the Hawk gave chase--a very vain chase I imagined it would prove. It lasted for about half a minute, the Pigeon rushing wildly round in wide circles, now mounting aloft and now plunging downwards close to the surface, the Carancho hotly following all the time. At length, evidently in great terror, the hunted bird flew down, alighting within a yard and a half of my feet. I stooped to take hold of it, when, becoming frightened at my action, it flew straight up and was seized in the talons of its pursuer close to my face and carried away.

In the next case the bird attacked was the Spur-winged Lapwing, the irreconcilable enemy of the Carancho and its bold and persistent persecutor. The very sight of this Hawk rouses the Lapwings to a frenzy of excitement, and springing aloft they hasten to meet it in mid-air screaming loudly, and continue to harry it until it leaves their ground, after which they return, and, ranged in triplets, perform their triumphal dances, accompanied with loud drumming notes. But if their hated foe alights on the ground, or on some elevation near them, they hover about him, and first one, then another, rushes down with the greatest violence, and gliding near him turns the bend of its wing so that the spur appears almost to graze his head. While one bird is descending, others are rising upwards to renew their charges; and this persecution continues until they drive him away, or become exhausted with their fruitless efforts. The Carancho, however, takes little notice of his tormentors; only when the Plover comes very close, evidently bent on piercing his skull with its sharp weapon, he quickly dodges his head, after which he resumes his indifferent demeanour until the rush of the succeeding bird takes place.

While out riding one day a Carancho flew past me attended by about thirty Lapwings, combined to hunt him from their ground, for it was near the breeding-season, when their jealous irascible temper is most excited. All at once, just as a Lapwing swept close by and then pa.s.sed on before it, the Hawk quickened its flight in the most wonderful manner and was seen in hot pursuit of its tormentor. The angry hectoring cries of the Lapwings instantly changed to piercing screams of terror, which in a very short time brought a crowd numbering between two and three hundred birds to the rescue. Now, I thought, the hunted bird will escape, for it twisted and turned rapidly about, trying to lose itself amongst its fellows, all hovering in a compact cloud about it and screaming their loudest. But the Carancho was not to be shaken off; he was never more than a yard behind his quarry, and I was near enough to distinguish the piteous screams of the chased Lapwing amidst all the tumult, as of a bird already captive. At the end of about a minute it was seized in the Carancho's talons, and, still violently screaming, borne away. The cloud of Lapwings followed for some distance, but presently they all returned to the fatal spot where the contest had taken place; and for an hour afterwards they continued soaring about in separate bodies, screaming all the time with an unusual note in their voices as of fear or grief, and holding excited conclaves on the ground, too all appearance as greatly disturbed in their minds as an equal number of highly emotional human beings would be in the event of a similar disaster overtaking them.

It is not often, however, that the Carancho ventures singly to attack adult and vigorous birds, except Tinamous; they prey by preference on the young or ailing, on small lambs and pigs left at a distance by their dams; and they also frequently attack and kill old and weakly sheep.

Where anything is wrong with bird or beast they are very quick to detect it, and will follow a sportsman to pick up the wounded birds, intelligently keeping at a safe distance themselves. I once shot a Flamingo in the grey stage of plumage and had some trouble to cross the stream, on the opposite side of which the bird, wounded very slightly, was rapidly stalking away. In three or four minutes I was over and found my Flamingo endeavouring to defend itself against the a.s.saults of a Carancho which had marked it for its own, and was striking it on the neck and breast in the most vigorous and determined way, sometimes from above, at other times alighting on the ground before it and springing up to strike like a game-c.o.c.k. A spot of blood on the plumage of the wounded bird, which had only one wing slightly damaged, had been sufficient to call down the attack; for to the Carancho a spot of blood, a drooping wing, or any irregularity in the gait, quickly tells its tale.

When several of these birds combine they are very bold. A friend told me that while voyaging on the Parana river a Black-necked Swan flew past him hotly pursued by three Caranchos; and I also witnessed an attack by four birds on a widely different species. I was standing on the bank of a stream on the pampas watching a great concourse of birds of several kinds on the opposite sh.o.r.e, where the carca.s.s of a horse, from which the hide had been stripped, lay at the edge of the water. One or two hundred Hooded Gulls and about a dozen Chimangos were gathered about the carca.s.s, and close to them a very large flock of Glossy Ibises were wading about in the water, while amongst these, standing motionless in the water, was one solitary White Egret. Presently four Caranchos appeared, two adults and two young birds in brown plumage, and alighted on the ground near the carca.s.s. The young birds advanced at once and began tearing at the flesh; while the two old birds stayed where they had alighted, as if disinclined to feed on half-putrid meat. Presently one of them sprung into the air and made a dash at the birds in the water, and instantly all the birds in the place rose into the air screaming loudly, the two young brown Caranchos only remaining on the ground. For a few moments I was in ignorance of the meaning of all this turmoil, when, suddenly, out of the confused black and white cloud of birds the Egret appeared, mounting vertically upwards with vigorous measured strokes. A moment later and first one, then the other, Carancho also emerged from the cloud, evidently pursuing the Egret, and only then the two brown birds sprung into the air and joined in the chase. For some minutes I watched the four birds toiling upwards with a wild zigzag flight, while the Egret, still rising vertically, seemed to leave them hopelessly far behind. But before long they reached and pa.s.sed it, and each bird as he did so would turn and rush downwards, striking at the Egret with his claws, and while one descended the others were rising, bird following bird with the greatest regularity. In this way they continued toiling upwards until the Egret appeared a mere white speck in the sky, about which the four hateful black spots were still revolving.

I had watched them from the first with the greatest excitement, and now began to fear that they would pa.s.s from sight and leave me in ignorance of the result; but at length they began to descend, and then it looked as if the Egret had lost all hope, for it was dropping very rapidly, while the four birds were all close to it striking at it every three or four seconds. The descent for the last half of the distance was exceedingly rapid, and the birds would have come down almost at the very spot they started from, which was about forty yards from where I stood, but the Egret was driven aside, and sloping rapidly down struck the earth at a distance of two hundred and fifty yards from the starting point. Scarcely had it touched the ground before the hungry quartette were tearing it with their beaks. They were all equally hungry no doubt, and perhaps the old birds were even hungrier than their young; and I am quite sure that if the flesh of the dead horse had not been so far advanced towards putrefaction they would not have attempted the conquest of the Egret.

I have so frequently seen a pure white bird singled out for attack in this way, that it has always been a great subject of wonder to me how the two common species of snow-white Herons in South America are able to maintain their existence; for their whiteness exceeds that of other white Waterfowl, while, compared with Swans, Storks, and the Wood-Ibis, they are small and feeble. I am sure that if these four Caranchos had attacked a Glossy Ibis they would have found it an easier conquest; yet they singled out the Egret, purely, I believe, on account of its shining white conspicuous plumage.

This wing-contest was a very splendid spectacle, and I was very glad that I had witnessed it, although it ended badly for the poor Egret; but in another case of a combined attack by Caranchos there was nothing to admire except the intelligence displayed by the birds in combining, and much to cause the mind to revolt against the blindly destructive ferocity exhibited by Nature in the instincts of her creatures. This scene was witnessed by a beloved old Gaucho friend of mine, a born naturalist, who related it to me. It was in summer, and he was riding in a narrow bridle-path on a plain covered with a dense growth of giant thistles, nine or ten feet high, when he noticed some distance ahead several Caranchos hovering over one spot; and at once conjectured that some large animal had fallen there, or that a traveller had been thrown from his horse and was lying injured amongst the thistles. On reaching the spot, he found an open s.p.a.ce of ground about forty yards in diameter, surrounded by the dense wall of close-growing thistles, and over this place the birds were flying, while several others were stationed near, apparently waiting for something to happen. The attraction was a large male Rhea squatting on the ground, and sheltering with its extended wings a brood of young birds. My friend was not able to count them, but there were not fewer than twenty-five or thirty young birds, small tender things, only a day or so out of the sh.e.l.l. As soon as he rode into the open s.p.a.ce of ground, the old Ostrich sprung up, and with lowered head, clattering beak, and broad wings spread out like sails, rushed at him; his horse was greatly terrified, and tried to plunge into the dense ma.s.s of thistles, so that he had the greatest difficulty in keeping his seat. Presently the Ostrich left him, and casting his eyes round he was astonished to see that all the young Ostriches were running about, scattered over the ground, while the Caranchos were pursuing, knocking down, and killing them. Meanwhile the old Ostrich was frantically rushing about trying to save them; but the Caranchos, when driven from one bird they were attacking, would merely rise a few yards and drop on the next one a dozen yards off; and as there were about fifteen Caranchos all engaged in the same way, the slaughter was proceeding at a great rate. My friend, who had been vainly struggling to get the better of his horse, was then forced to leave the place, and did not therefore see the end of the tragedy in which he had acted an involuntary part; but before going he saw that at least half the young birds were dead, and that these were all torn and bleeding on the small of the neck just behind the head, while in some cases the head had been completely wrenched off.

The Gauchos, when snaring Partridges (Tinamous), frequently bribe the Caranchos to a.s.sist them. The snarer has a long slender cane with a small noose at the extremity, and when he sights a Partridge he gallops round it in circles until the bird crouches close in the gra.s.s; then the circles are narrowed and the pace slackened, while he extends the cane, and lowers it gradually over the bewildered bird until the small noose is dropped over its head and it is caught. Many Partridges are not disposed to sit still to be taken in this open barefaced way; but if the snarer keeps a Carancho hovering about by throwing him an occasional gizzard, the wariest Partridge is so stricken with fear that it will sit still and allow itself to be caught.

In the love-season the male Caranchos are frequently seen fighting; and sometimes, when the battle is carried on at a great height in the air, the combatants are seen clasped together and falling swiftly towards the earth; but in all the contests I have witnessed the birds have not been so blinded with pa.s.sion as to fall the whole distance before separating.

Besides these single combats, in which unpaired or jealous males engage in the love-season, there are at all times occasional dissensions amongst them, the cause of which it would be difficult to determine.

Here again, as often in hunting, the birds combine to punish an offender, and in some cases the punishment is death.

Their cry is exceedingly loud and harsh, a short abrupt note, like _cruk_, repeated twice; after which, if the bird is violently agitated, as when wounded or fighting, it throws its head backwards until the crown rests on the back, and rocks it from side to side, accompanying the action with a prolonged piercing cry of great power. This singular gesture of the Carancho, unique among birds, seems to express very forcibly a raging spirit, or, perhaps, rage mingled with despair.

The nest is built in a variety of situations: on trees, where there are any, but on the treeless pampas, where the Carancho is most at home, it is made on the ground, sometimes among the tall gra.s.s, while a very favourite site is a small islet or mound of earth rising well out of the water. When a suitable place has been found, the birds will continue to use the same nest for many consecutive years. It is a very large slovenly structure of sticks, mixed with bones, pieces of skin, dry dung, and any portable object the bird may find to increase the bulk of his dwelling. The eggs are three or four, usually the last number, slightly oval, and varying greatly in colour and markings, some having irregular dark red blotches on a cream-coloured ground, while others are entirely of a deep brownish red, with a few black marks and blotches.

Fam. x.x.xIII. CATHARTIDae, or CONDORS

The American Vultures, or Condors as it is better to call them, are now universally admitted to be quite distinct from the rest of the Accipitres and to const.i.tute a family apart. They differ from the Falconidae in having the hind toe inserted at a higher level than the others, and in the nostrils being pervious, owing to the absence of the bony septum, besides in other important characters[2].

[2] _Cf._ Standard Nat. Hist. vol. iv., Birds, p. 266 (Boston, 1885).

The Cathartidae are few in number, only some six or seven species being accurately known. Of these, three occur within the limits of the Argentine Republic.

311. CATHARTES AURA (Linn.).

(TURKEY-VULTURE.)

+Cathartes aura+, _Scl. et Salv. Nomencl._ p. 123; _White, P. Z. S._ 1882, p. 624 (Misiones); _Burm. La-Plata Reise_, ii. p. 433 (Mendoza, Catamarca, Tuc.u.man). +nops aura+, _Sharpe, Cat. B._ i. p. 25. +Rhinogryphus aura+, _Baird, Brew., et Ridgw. N. A. B._ iii. p. 344.

_Description._--Plumage black, the feathers above edged more or less with dull brown; head and neck bare, bright red in life: whole length 300 inches, wing 215, tail 115. _Female_ similar.

_Hab._ Temperate and Tropical America, and south to Chili and the Falkland Islands.

In Argentina the Turkey-Vulture appears only to occur in the northern and western provinces. Dr. Burmeister noticed it occasionally in Mendoza, Catamarca, and Tuc.u.man. In Misiones, White found it abundant at Concepcion. I met with it in Patagonia, but it is by no means common there, and is only seen singly or in pairs.

312. CATHARTES ATRATUS (Bartram).

(BLACK VULTURE.)

+Cathartes ftans+, _Burm. La-Plata, Reise_, ii. p. 433 (Mendoza, Tuc.u.man). +Cathartes atratus+, _Darwin, Zool. Beagle_, iii. p. 7 (Rio Negro); _Scl. et Salv. Nomencl._ p. 123; _Sclater, P. Z. S._ 1872, p. 536 (Rio Negro); _Barrows, Auk_, 1884, p. 113 (Pampas).

+Catharista atrata+, _Baird, Brew., et Ridgw. N. A. B._ iii. p.

351.

_Description._--Plumage black; head bare, black: whole length 250 inches, wing 175, tail 85. _Female_ similar.

_Hab._ Eastern U.S., and Central and Southern America to Chili and the Rio Negro of Patagonia.

According to Dr. Burmeister the Black Vulture is found throughout the Argentine Pampas, but is commoner in the east and north. It is known as the "_Gallinazo_" at Mendoza, and "_Cuervo_" in Tuc.u.man. Mr. Barrows tells us that he did not see it during his residence at Concepcion, but was told of its former abundance in times of drought, when dead sheep were numerous. It was, however, met with by him in small numbers during his excursion through the Sierras of the Pampas south of Buenos Ayres.

On the Rio Negro of Patagonia I found these Vultures abundant, especially near the settlement of El Carmen, where, attracted by the refuse of the cattle-slaughtering establishments, they congregated in immense numbers, and were sometimes seen crowded together in thousands on the trees, where they roosted. Darwin observed them at the same place, and has described their soaring habits at considerable length.

The following account of the nesting-habits of this species is given by Mr. John J. Dalgleish (Proc. Roy. Phys. Soc. Edinb. vi. p. 237):--"The eggs seldom, if ever, exceed two in number, and are usually laid in a hollow tree or on the ground. Their average weight is about a pound.