The Naturalist in La Plata | Page 7

Mendoza, and has never colonized the grassy pampas. The Tatusia hybrida, called "little mule" from the length of its ears, and the Dasypus tricinctus, which, when disturbed, rolls itself into a ball, the wedge-shaped head and wedge-shaped tail admirably fitting into the deep-cut shell side by side; and the quirquincho (Dasypus minutus), all inhabit the pampa, are diurnal, and feed exclusively on insects, chiefly ants. Wherever the country becomes settled, these three disappear, owing to the dulness of their senses, especially that of sight, and to the diurnal habit, which was an advantage to them, and enabled them to survive when rapacious animals, which are mostly nocturnal, were their only enemies. The fourth, and most important, is the hairy armadillo, with habits which are in strange contrast to those of its perishing congeners, and which seem to mock many hard-and-fast rules concerning animal life. It is omnivorous, and will thrive on anything from grass to flesh, found dead and in all stages of decay, or captured by means of its own strategy. Furthermore, its habits change to suit its conditions: thus, where nocturnal carnivores are its enemies, it is diurnal; but where man appears as a chief persecutor, it becomes nocturnal. It is much hunted for its flesh, dogs being trained for the purpose; yet it actually becomes more abundant as population increases in any district; and, if versatility in habits or adaptiveness can be taken as a measure of intelligence, this poor armadillo, a survival of the past, so old on the earth as to have existed contemporaneously with the giant glyptodon, is the superior of the large-brained cats and canines.
To finish with the mammalia, there are two interesting opossums, both of the genus Didelphys, but in habits as wide apart as cat from otter. One of these marsupials appears so much at home on the plains that I almost regret having said that the vizcacha alone gives us the idea of being in its habits the product of the pampas. This animal--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 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,