ground shows a very extended front--a representation in bird-life of the "thin red line"--and advances by the hindmost birds constantly flying over the others and alighting in the front ranks.
Among the tyrant-birds are several species of the beautiful wing-banded genus, snow-white in colour, with black on the wings and tail: these are extremely graceful birds, and strong flyers, and in desert places, where man seldom intrudes, they gather to follow the traveller, calling to each other with low whistling notes, and in the distance look like white flowers as they perch on the topmost stems of the tall bending grasses.
The most characteristic pampean birds are the tinamous--called partridges in the vernacular--large as a fowl, and the spotted tinamou, which is about the size of the English partridge. Their habits are identical: both lay eggs of a beautiful wine-purple colour, and in both species the young acquire the adult plumage and power of flight when very small, and fly better than the adults. They have small heads, slender curved beaks, unfeathered legs and feet, and are tailless; the plumage is deep yellowish, marked with black and brown above. They live concealed, skulking like rails through the tall grass, fly reluctantly, and when driven up, their flight is exceedingly noisy and violent, the bird soon exhausting itself. They are solitary, but many live in proximity, frequently calling to each other with soft plaintive voices. The evening call-notes of the larger bird are flute-like in character, and singularly sweet and expressive.
26 The Naturalist in La Plata.
The last figure to be introduced into this sketch--which is not a catalogue--is that of the Rhea. Glyptodon, Toxodon, Mylodon, Megatherium, have passed away, leaving no descendants, and only pigmy representatives if any; but among the feathered inhabitants of the pampa the grand archaic ostrich of America survives from a time when there were also giants among the avians. Vain as such efforts usually are, one cannot help trying to imagine something of the past history of this majestic bird, before man came to lead the long chase now about to end so mournfully. Its fleetness, great staying powers, and beautiful strategy when hunted, make it seem probable that it was not without pursuers, other than the felines, among its ancient enemies, long-winded and tenacious of their quarry; and these were perhaps of a type still represented by the wolf or hound-like aguará and aguara-guazú. It might be supposed that when almost all the larger forms, both mammal and bird, were overtaken by destruction, and when the existing rhea was on the verge of extinction, these long-legged swift canines changed their habits and lost their bold spirit, degenerating at last into hunters of small birds and mammals, on which they are said to live.
The rhea possesses a unique habit, which is a puzzle to us, although it probably once had some significance--namely, that of running, when hunted, with one wing raised vertically, like a great sail--a veritable "ship of the wilderness." In every way it is adapted to the conditions of the pampas in a far greater degree than other pampean birds, only excepting the rufous and spotted tinamous. Its
The Desert Pampas. 27
commanding stature gives it a wide horizon; and its dim, pale, bluish-grey colour assimilates to that of the haze, and renders it invisible at even a moderate distance. Its large form fades out of sight mysteriously, and the hunter strains his eyes in vain to distinguish it on the blue expanse. Its figure and carriage have a quaint majestic grace, somewhat unavian in character, and peculiar to itself. There are few more strangely fascinating sights in nature than that of the old black-necked cock bird, standing with raised agitated wings among the tall plumed grasses, and calling together his scattered hens with hollow boomings and long mysterious suspira-tions, as if a wind blowing high up in the void sky had found a voice. Rhea-hunting with the bolas, on a horse possessing both speed and endurance, and trained to follow the bird in all his quick doublings, is unquestionably one of the most fascinating forms of sport ever invented, by man. The quarry has even more than that fair chance of escape, without which all sport degenerates into mere butchery, unworthy of rational beings; moreover, in this unique method of hunting the ostrich the capture depends on a preparedness for all the shifts and sudden changes of course practised by the bird when closely followed, which is like instinct or intuition; and, finally, in a dexterity in casting the bolas at the right moment, with a certain aim, which no amount of practice can give to those who are not to the manner born.