water in the rushy pools, though it was at the height of the dry season. This whole plain was covered with an endless flock of chakars, not in close order, but scattered about in pairs and small groups. In this desolate spot I found a small rancho inhabited by a gaucho and his family, and I spent the night with them. The birds were all about the house, apparently as tame as the domestic fowls, and when I went out to look for a spot for my horse to feed on, they would not fly away from me, but merely moved, a few steps out of my path About nine o'clock we were eating supper in the rancho when suddenly the entire multitude of birds covering the marsh for miles around burst forth into a tremendous evening song. It is impossible to describe the effect of this mighty rush of sound; but let the reader try to imagine half-a-million voices, each far more powerful than that one which makes itself heard all over Regent's Park, bursting forth on the silent atmosphere of that dark lonely plain. One peculiarity was that in this mighty noise, which sounded louder than the sea thundering on a rocky coast, I seemed to be able to distinguish hundreds, even thousands, of individual voices. Forgetting my supper, I sat motionless and overcome with astonishment, while the air, and even the frail rancho, seemed to be trembling in that tempest of sound. When it ceased my host remarked with a smile, "We are accustomed to this, señor--every evening we have this concert." It was a concert well worth riding a hundred miles to hear. But the chakar country is just now in a transitional state, and the precise conditions which
The Crested Screamer. 229
made it possible for birds so large in size to form such immense congregations are rapidly passing away. In desert places, the bird subsists chiefly on leaves and seeds of aquatic plants; but when the vast level area of the pampas was settled by man, the ancient stiff grass-vegetation gave place to the soft clovers and grasses of Europe, and to this new food the birds took very kindly. Other circumstances also favoured their increase. They were never persecuted, for the natives do not eat them, though they are really very good--the flesh being something like wild goose in flavour. A higher civilization is changing all this: the country is becoming rapidly overrun with emigrants, especially by Italians, the pitiless enemies of all bird-life.
The chakars, like the skylark, love to soar upwards when singing, and at such times when they have risen till their dark bulky bodies appear like floating specks on the blue sky, or until they disappear from sight altogether, the notes become wonderfully etherealized by distance to a soft silvery sound, and it is then very delightful to listen to them.
It seems strange that so ponderous a fowl with only six feet and a half spread of wings should possess a power of soaring equal to that of vultures and eagles. Even the vulture with its marvellous wing power soars chiefly from necessity, and when its crop is full finds no pleasure in "scaling the heavens by invisible stairs." The chakar leaves its grass-plot after feeding and soars purely for recreation, taking so much pleasure in its aerial
230 The Naturalist in La Plata.
exercises that in bright warm weather, in winter and spring, it spends a great part of the day in the upper regions of the air. On the earth its air is grave and its motions measured and majestic, and it rises with immense labour, the wings producing a sound like a high wind. But as the bird mounts higher, sweeping round as it ascends, just as vultures and eagles do, it gradually appears to become more buoyant, describing each succeeding circle with increasing grace. I can only account for this magnificent flight, beginning so laboriously, by supposing that the bubble space under the skin becomes inflated with an air lighter than atmospheric air, enabling a body so heavy with wings disproportionately short to float with such ease and evident enjoyment at the vast heights to which the bird ascends. The heavenward flight of a large bird is always a magnificent spectacle; that of the chakar is peculiarly fascinating on account of the resounding notes it sings while soaring, and in which the bird seems to exult in its sublime power and freedom.
I was once very much surprised at the behaviour of a couple of chakars during a thunderstorm. On a still sultry day in summer I was standing watching masses of black cloud coming rapidly over the sky, while a hundred yards from me stood the two birds also apparently watching the approaching storm with interest. Presently the edge of the cloud touched the sun, and a twilight gloom fell on the earth. The very moment the sun disappeared the birds rose up and soon began singing their long' resounding notes, though it was loudly thundering