18
The Naturalist in La Plata,
Didelphys crassicaudata--has a long slender, wedge-, shaped head and body, admirably adapted for pushing through the thick grass and rushes; for it is both terrestrial and aquatic, therefore well suited to inhabit low, level plains liable to be flooded. On dry land its habits are similar to those of a weasel; in lagoons, where it dives and swims with great ease, it constructs a globular nest suspended from the rushes. The fur is soft, of a rich yellow, reddish above, and on the sides and under surfaces varying in some parts to orange, in others exhibiting beautiful copper and terra-cotta tints. These lovely tints and the metallic lustre soon fade from the fur, otherwise this animal would be much sought after in the interests of those who love to decorate themselves with the spoils of beautiful dead animals--beast and bird. The other opossum is the black and white Didelphys azarae; and it is indeed strange to find this animal on the pampas, although its presence there is not so mysterious as that of the tuco-tuco. It shuffles along slowly and awkwardly on the ground, but is a great traveller nevertheless. Tschudi met it mountaineering on the Andes at an enormous altitude, and, true to its lawless nature, it confronted me in Patagonia, where the books say no marsupial dwells. In every way it is adapted to an arboreal life, yet it is everywhere found on the level country, far removed from the conditions which one would imagine to be necessary to its existence. For how many thousands of years has this marsupial been a dweller on the plain, all its best faculties unexercised, its beautiful grasping hands pressed to the ground, and its prehensile tail
The Desert Pampas. 19
dragged like an idle rope behind it! Yet, if one is brought to a tree, it will take to it as readily as a duck to water, or an armadillo to earth, climbing up the trunk and about the branches with a monkey-like agility. How reluctant Nature seems in some cases to undo her own work! How long she will allow a specialized organ, with the correlated instinct, to rest without use, yet ready to flash forth on the instant, bright and keen-edged, as in the ancient days of strife, ages past, before peace came to dwell on earth!
The avi-fauna is relatively much richer than the mammalia, owing to the large number of aquatic species, most of which are migratory with their "breeding" or "subsistence-areas" on the pampas. In more senses than one they constitute a "floating population," and their habits have in no way been modified by the conditions of the country. The order, including storks, ibises, herons, spoonbills, and flamingoes, counts about eighteen species; and the most noteworthy birds in it are two great ibises nearly as large as turkeys, with mighty resonant voices. The duck order is very rich, numbering at least twenty species, including two beautiful upland geese, winter visitors from Magellanic lands, and two swans, the lovely black-necked, and the pure white with rosy bill. Of rails, or ralline birds, there are ten or twelve, ranging from a small spotted creature no bigger than a thrush to some large majestic birds. One is the courlan, called "crazy widow" from its mourning plumage and long melancholy screams, which on still evenings may be heard a league away. Another is the
20 The Naturalist in La Plata.
graceful variegated ypicaha, fond of social gatherings, where the birds perform a dance and make the desolate marshes resound with their insane humanlike voices. A smaller kind, Porphyriops melanops, has a night-cry like a burst of shrill hysterical laughter, which has won for it the name of "witch;" while another, Rallus rythyrhynchus, is called "little donkey" from its braying cries. Strange eerie voices have all these birds. Of the remaining aquatic species, the most important is the spur-winged crested screamer; a noble bird as large as a swan, yet its favourite pastime is to soar upwards until it loses itself to sight in the blue ether, whenca it pours forth its resounding choral notes, which reach the distant earth clarified, and with a rhythmic swell and fall as of chiming bells. It also sings by night, "counting the hours," the gauchos say, and where they have congregated together in tens of thousands the mighty roar of their combined voices produces an astonishingly grand effect.