Mutual Aid by Peter Kropotkin (ebook reader play store .txt) 📕

to E. S. Holden, live round the Lick observatory “on a mixed diet of Manzanita berries and astronomers’ chickens” (Nature, Nov. 5, 1891), seem also to be very sociable.

Some very interesting instances of the love of society among animals have lately been given by Mr. C. J. Cornish (Animals at Work and Play, London, 1896). All animals, he truly remarks, hate solitude. He gives also an amusing instance of the habit of the prairie dogs of keeping sentries. It is so great that they always keep a sentinel on duty, even at the London Zoological Garden, and in the Paris Jardin d’Acclimatation (p. 46).

Professor Kessler was quite right in pointing out that the young broods of birds, keeping together in autumn, contribute to the development of feelings of sociability. Mr. Cornish (Animals at Work and Play) has given several examples of the plays of young mammals, such as, for instance, lambs playing at “follow my leader,” or at “I’m the king of the castle,” and their love of steeplechases; also the fawns playing a kind of “cross-touch,” the touch being given by the nose. Altogether we have, moreover, the excellent work by Karl Gross, The Play of Animals.

V Checks to Over-Multiplication

Hudson, in his Naturalist on the La Plata (Chapter III), has a very interesting account of a sudden increase of a species of mice and of the consequences of that sudden “wave of life.” “In the summer of 1872⁠–⁠73,” he writes, “we had plenty of sunshine, with frequent showers, so that the hot months brought no dearth of wild flowers, as in most years.” The season was very favourable for mice, and “these prolific little creatures were soon so abundant that the dogs and the cats subsisted almost exclusively on them. Foxes, weasels and opossums fared sumptuously; even the insectivorous armadillo took to mice-hunting.” The fowls became quite rapacious, “while the sulphur tyrant-birds (Pitangus) and the Guira cuckoos preyed on nothing but mice.” In the autumn, countless numbers of storks and of short-eared owls made their appearance, coming also to assist at the general feast. Next came a winter of continued drought; the dry grass was eaten, or turned to dust; and the mice, deprived of cover and food, began to die out. The cats sneaked back to the houses; the short-eared owls⁠—a wandering species⁠—left; while the little burrowing owls became so reduced as scarcely to be able to fly, “and hung about the houses all day long on the lookout for some stray morsel of food.” Incredible numbers of sheep and cattle perished the same winter, during a month of cold that followed the drought. As to the mice, Hudson makes the remark that “scarcely a hard-pressed remnant remains after the great reaction, to continue the species.”

This illustration has an additional interest in its showing how, on flat plains and plateaus, the sudden increase of a species immediately attracts enemies from other parts of the plains, and how species unprotected by their social organization must necessarily succumb before them.

Another excellent illustration in point is given by the same author from the Argentine Republic. The coypù (Myiopotamus coypù) is there a very common rodent⁠—a rat in shape, but as large as an otter. It is aquatic in its habits and very sociable. “Of an evening,” Hudson writes, “they are all out swimming and playing in the water, conversing together in strange tunes, which sound like the moans and cries of wounded and suffering men. The coypù, which has a fine fur under the long coarse hair, was largely exported to Europe; but some sixty years ago the Dictator Rosas issued a decree prohibiting the hunting of this animal. The result was that the animals increased and multiplied exceedingly, and, abandoning their aquatic habits, they became terrestrial and migratory, and swarmed everywhere in search of food. Suddenly a mysterious malady fell on them, from which they quickly perished, and became almost extinct” (p. 12).

Extermination by man on the one side, and contagious diseases on the other side, are thus the main checks which keep the species down⁠—not competition for the means of existence, which may not exist at all.

Facts, proving that regions enjoying a far more congenial climate than Siberia are equally underpopulated, could be produced in numbers. But in Bates’ well-known work we find the same remark concerning even the shores of the Amazon river.

“There is, in fact,” Bates wrote, “a great variety of mammals, birds and reptiles, but they are widely scattered and all excessively shy of man. The region is so extensive and uniform in the forest-clothing of its surface, that it is only at long intervals that animals are seen in abundance, where some particular spot is found which is more attractive than the others” (Naturalist on the Amazon, 6th ed., p. 31).

This fact is the more striking as the Brazilian fauna, which is poor in mammals, is not poor at all in birds, and the Brazilian forests afford ample food for birds, as may be seen from a quotation, already given on a previous page, about birds’ societies. And yet, the forests of Brazil, like those of Asia and Africa, are not overpopulated, but rather underpopulated. The same is true concerning the pampas of South America, about which W. H. Hudson remarks that it is really astonishing that only one small ruminant should be found on this immense grassy area, so admirably suited to herbivorous quadrupeds. Millions of sheep, cattle and horses, introduced by man, graze now, as is known, upon a portion of these prairies. Land-birds on the pampas are also few in species and in numbers.

VI Adaptations to Avoid Competition

Numerous examples of such adaptations can be found in the works of all field-naturalists. One of them, very interesting, may be given in the hairy armadillo, of which W. H. Hudson says, that “it has struck a line for itself, and consequently thrives, while its congeners are