THE SOUTH AMERICAN STEPPE.
BREHM was among the first naturalist-travellers to note the common resemblance of the " steppe " regions of the world, and the marked difference in the life of these animals from that led by the fauna of other portions of the earth. He found that life on the high plains of Southern Africa so closely resembled that of the Asiatic steppe in its general features, the African drought taking the place of the Asian winter, and producing results in famine and suspended life similar to those caused by winter in the other continent, that he gave to all this region the title of "the African steppe." The comparison was most suggestive. It led to conclusions from the likeness of general phenomena in widely separated regions which would never have been reached by a mere survey of the life of the African highlands as a separate and individual area.
To his synoptic view of these two great regions of plains 6 third should be added if the general resemblances or differences of life on the steppe regions are to be understood. Had Brehm visited the pampas of La Plata and the Pats• gonian plains, he would have added a piciture;of another set of steppe types to his " aspects of Nature " from the point of view of the naturalist. But while the natural features of the South American steppe are constant, except as man may alter its vegetation, by giving turf for pampas grasses, and planting woods on the treeless plains, its animal life is under- going such a rapid change that Brehm himself might have declined to predict its future. Without attempting such a prophecy here, we may set out some of the recent history of the succession of animal life on these plains south of the La Plata.
When Darwin visited the pampas and the pebble plains of Patagonia, and crossed the "Camps" of Buenos Ares, there were hundreds of leagues in which the plains were in the condition of the primitive steppe, so like those of South Siberia that it is a little surprising that Darwin does not mention the parallel. There are the clay steppes and the pebble steppes as in Central Asia, the latter studded with thin thorny vegeta- tion and inhabited, as one naturally expects, by the camel- like wild lamas or " guanacos," hare-like cavies, and viscachas. There is a "natural conformity" between these creatures of the New World's stony desert and the wild camels, the steppe hares, and the " sousliks," or Asiatic prairie-doge, of the corresponding regions in the Old World. The two areas of stony steppe had produced an almost identical fauna in two different hemispheres:
But Darwin was more intent on the present and past of the creatures of the pampas and the Southern deserts than on drawing parallels, or on drawing inferences from the production of analogous species on similar tracts of the earth's surface. On the clay steppe of the pampas he saw the curious pheno- menon of a land capable of supporting animal life in quantities almost without parallel elsewhere, a land where the natural grasses were hindered in their growth neither by shrub nor tree, and in parts only broken by brilliant flowers, geraniums, scarlet verbena, wood sorrel, and cenotherm, stretching like an Atlantic Ocean of green from the sea to the foot-hills of the Cordilleras on the opposite side of the continent. Nature seemed to have left out every product which could take up room which would otherwise be occupied by the precious grasses. There were no useless rookie and almost no stones ; no trees, to kill herbage by their shade, few marshes or arid belts of sand or salt, no mountains. The steppe offered spontaneously that monotony of feature which agriculture produces elsewhere after generations of labour. It was the pastures of Romney Marsh multiplied by a hundred thousand, or like some vast natural reclamation, made ready for the flocks and herds of a continent. Yet to consume this half-million square miles of food, instead of legions of bison and wapiti-deer, as on the Northern prairies, there were not enough native animals to crop the grasses. South America has no wild oxen, or wild sheep, or goats, or antelopes. Of those mammals which it does possess, the sloths, monkeys, and opossums do not descend further south than the forest line; and on the pampas and the Southern plains there was only one large native ruminant animal, the pampas stag, with the puma and jaguar, which have probably been attracted south by the increase of imported animals which serve them as food.
Add to these the ante-aters, armadillos, the ostrich (rhea), and the zorilla, or skunk polecat, both of the last of which have their counterpart on the South African steppe, and the considerable mammals of this steppe are exhausted. Darwin's belief was that this scarcity of animal life on these plains was also very recent, and that the splitting up of the continents of North and South America zoologically was effected by the rising of the high Mexican plateau, beyond which few Northern species wandered south, among them being the peccary, puma, and opossum. The giant beasts of a previous, though late, period were found both on the pampas and in North America, when most of the now exist- ing shells were living. "I know of no other instance," Darwin writes, "where we can almost mark the period and manner of the splitting up of one great region into two well-characterised zoological provinces." We think the still later changes in this region, doe solely to man, almost as striking. Man has filled in the blank left by Nature with a fauna brought there across the ocean. These animals have multiplied faster than ever did the bison herds, and have changed, or are changing, the surface of the steppe. Even at the beginning of the century these fiats were a vast region of emptiness, grazed, it is true, by the troops of wild horses and by a few deer, though the climate and food were so adapted to the horses that in forty-three years they had spread from La Plata to the Straits of Magellan, and were there in use by the Indians. " The number of horses and the profusion of food are the destruction of all industries," Mr. Darwin wrote. Since then what struck him as abundance has increased to a degree which words are inadequate to describe. A population of forty-five thousand British settlers recently owned thirty. six million sheep, besides cattle and horses. The whole cenens of sheep is over one, hundred million; of cattle forty million.
It was estimated last spring that in the State of Washing. ton, one of the Territories in the extreme North-West of the United States where wild game is still almost as numerous as in the old days, there were over one hundred thousand wild deer, with about thirty thousand " elk " or wapiti. This rough census of the two most numerous species of big game in a favourite region and suitable climate is simply insignificant in comparison with the head of half wild domesticated species now at large on the pampas of the Southern steppe, making due allowance for the differ- ence in area. That of Washington State is 66,000 square miles, or about one-twelfth of the Argentine plains, omitting the Indian Territories. Setting the "elk" of Washington . against the cattle of the pampas, and comparing the sheep of the latter with the deer, that is mule-deer and black-tailed deer, the common species of the North-Western States, the number of sheep on an acreage as large as the State of Washington is more than eight millions. In other words, if the natural head of wild game maintained by the State of Washington were proportioned to the number of one domesticated species grazing on the pampas, the State would support not one hundred thousand deer, but eight millions of deer ! Formerly the grey and misty levels of these plains showed in winter but little life except the scattered herds of wild horses, and the viscachas sitting by their burrows. Now on these chosen pastures the hordes of cattle blacken the plains. The millions of sheep, herded by dogs which have become almost part of the flocks, outnumber the ancient "treks" of the springbok of South Africa. Instead of the vast and oppressive silence of the plains, the lowing of herds and the bleating of flocks fill the air with sound. And yet we are said to be only at the beginning of this great artificial revival of animal life. That modification of the herbage which Darwin noted as produced by cattle in the more populous and anciently settled territories has spread over millions of acres. On these the tall, rough grass, so high that cattle could not be seen in it except the gauchos stood on their horses as look-out posts to gain a view, has given way to turf, close, compact, and of treble the nutritive powers of the unimproved grasses. As the cattle and sheep increased almost beyond the possibility of consumption as food, while the former were killed for their hides and the latter for their tallow, the very birds became demoralised and car- nivorous, like the beef-eating human population. The whole region of the pampas now swarms with those carnivorous hawks and vultures which Darwin noted as one among the significant features of the plains. The greater part of these millions of sheep and cattle are slaughtered in the country, and leave a large part of their carcases as offal round the estancias and slaughter-houses, for only trimmed carcases or the essence of beef in such forms as Bovril or Liebig are shipped across the sea. The vultures, eagles, buzzards, and caracara hawks gorge themselves daily on this waste flesh, and like the owls in the vole plague, become prodigiously prolific from high feeding, and are almost without fear of man, whose leavings they consume. Pumas and jaguars kill the sheep and colts ; and a race of feral cats has arisen which kills the game and wild fowl which the hawks, fed to repletion on beef and mutton, leave unmolested. Except in the occasional great droughts, this South American steppe is the most prolific in animal life of any region of the earth. Its production already runs to waste; yet its limits of production are scarcely within sight. When its turn comes to attract a human population at all in proportion to its capacity for feeding nations, it seems marked by Nature as the home for the most populous, and possibly the most prosperous, nation of the New World or the Old.
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