Mutual Aid: A Factor of Evolution. kniaz Petr Alekseevich Kropotkin

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СКАЧАТЬ for half an hour it was describing its wide circles in silence when at once its piercing voice was heard. Its cry was soon answered by another eagle which approached it, and was followed by a third, a fourth, and so on, till nine or ten eagles came together and soon disappeared. In the afternoon, Syevertsoff went to the place whereto he saw the eagles flying; concealed by one of the undulations of the Steppe, he approached them, and discovered that they had gathered around the corpse of a horse. The old ones, which, as a rule, begin the meal first—such are their rules of propriety-already were sitting upon the haystacks of the neighbourhood and kept watch, while the younger ones were continuing the meal, surrounded by bands of crows. From this and like observations, Syevertsoff concluded that the white-tailed eagles combine for hunting; when they all have risen to a great height they are enabled, if they are ten, to survey an area of at least twenty-five miles square; and as soon as any one has discovered something, he warns the others.(11) Of course, it might be argued that a simple instinctive cry of the first eagle, or even its movements, would have had the same effect of bringing several eagles to the prey. But in this case there is strong evidence in favour of mutual warning, because the ten eagles came together before descending towards the prey, and Syevertsoff had later on several opportunities of ascertaining that the whitetailed eagles always assemble for devouring a corpse, and that some of them (the younger ones first) always keep watch while the others are eating. In fact, the white-tailed eagle—one of the bravest and best hunters—is a gregarious bird altogether, and Brehm says that when kept in captivity it very soon contracts an attachment to its keepers.

      Sociability is a common feature with very many other birds of prey. The Brazilian kite, one of the most "impudent" robbers, is nevertheless a most sociable bird. Its hunting associations have been described by Darwin and other naturalists, and it is a fact that when it has seized upon a prey which is too big, it calls together five or six friends to carry it away. After a busy day, when these kites retire for their night-rest to a tree or to the bushes, they always gather in bands, sometimes coming together from distances of ten or more miles, and they often are joined by several other vultures, especially the percnopters, "their true friends," D'Orbigny says. In another continent, in the Transcaspian deserts, they have, according to Zarudnyi, the same habit of nesting together. The sociable vulture, one of the strongest vultures, has received its very name from its love of society. They live in numerous bands, and decidedly enjoy society; numbers of them join in their high flights for sport. "They live in very good friendship," Le Vaillant says, "and in the same cave I sometimes found as many as three nests close together."(12) The Urubu vultures of Brazil are as, or perhaps even more, sociable than rooks.(13) The little Egyptian vultures live in close friendship. They play in bands in the air, they come together to spend the night, and in the morning they all go together to search for their food, and never does the slightest quarrel arise among them; such is the testimony of Brehm, who had plenty of opportunities of observing their life. The red-throated falcon is also met with in numerous bands in the forests of Brazil, and the kestrel (Tinnunculus cenchris), when it has left Europe, and has reached in the winter the prairies and forests of Asia, gathers in numerous societies. In the Steppes of South Russia it is (or rather was) so sociable that Nordmann saw them in numerous bands, with other falcons (Falco tinnunculus, F. oesulon, and F. subbuteo), coming together every fine afternoon about four o'clock, and enjoying their sports till late in the night. They set off flying, all at once, in a quite straight line, towards some determined point, and, having reached it, immediately returned over the same line, to repeat the same flight.(14)

      To take flights in flocks for the mere pleasure of the flight, is quite common among all sorts of birds. "In the Humber district especially," Ch. Dixon writes, "vast flights of dunlins often appear upon the mud-flats towards the end of August, and remain for the winter. … The movements of these birds are most interesting, as a vast flock wheels and spreads out or closes up with as much precision as drilled troops. Scattered among them are many odd stints and sanderlings and ringed-plovers."(15)

      It would be quite impossible to enumerate here the various hunting associations of birds; but the fishing associations of the pelicans are certainly worthy of notice for the remarkable order and intelligence displayed by these clumsy birds. They always go fishing in numerous bands, and after having chosen an appropriate bay, they form a wide half-circle in face of the shore, and narrow it by paddling towards the shore, catching all fish that happen to be enclosed in the circle. On narrow rivers and canals they even divide into two parties, each of which draws up on a half-circle, and both paddle to meet each other, just as if two parties of men dragging two long nets should advance to capture all fish taken between the nets when both parties come to meet. As the night comes they fly to their resting-places—always the same for each flock—and no one has ever seen them fighting for the possession of either the bay or the resting place. In South America they gather in flocks of from forty to fifty thousand individuals, part of which enjoy sleep while the others keep watch, and others again go fishing.(16) And finally, I should be doing an injustice to the much-calumniated house-sparrows if I did not mention how faithfully each of them shares any food it discovers with all members of the society to which it belongs. The fact was known to the Greeks, and it has been transmitted to posterity how a Greek orator once exclaimed (I quote from memory):—"While I am speaking to you a sparrow has come to tell to other sparrows that a slave has dropped on the floor a sack of corn, and they all go there to feed upon the grain." The more, one is pleased to find this observation of old confirmed in a recent little book by Mr. Gurney, who does not doubt that the house sparrows always inform each other as to where there is some food to steal; he says, "When a stack has been thrashed ever so far from the yard, the sparrows in the yard have always had their crops full of the grain."(17) True, the sparrows are extremely particular in keeping their domains free from the invasions of strangers; thus the sparrows of the Jardin du Luxembourg bitterly fight all other sparrows which may attempt to enjoy their turn of the garden and its visitors; but within their own communities they fully practise mutual support, though occasionally there will be of course some quarrelling even amongst the best friends.

      Hunting and feeding in common is so much the habit in the feathered world that more quotations hardly would be needful: it must be considered as an established fact. As to the force derived from such associations, it is self-evident. The strongest birds of prey are powerless in face of the associations of our smallest bird pets. Even eagles—even the powerful and terrible booted eagle, and the martial eagle, which is strong enough to carry away a hare or a young antelope in its claws—are compelled to abandon their prey to bands of those beggars the kites, which give the eagle a regular chase as soon as they see it in possession of a good prey. The kites will also give chase to the swift fishing-hawk, and rob it of the fish it has captured; but no one ever saw the kites fighting together for the possession of the prey so stolen. On the Kerguelen Island, Dr. Coues saw the gulls to Buphogus—the sea-hen of the sealers—pursue make them disgorge their food, while, on the other side, the gulls and the terns combined to drive away the sea-hen as soon as it came near to their abodes, especially at nesting-time.(18) The little, but extremely swift lapwings (Vanellus cristatus) boldly attack the birds of prey. "To see them attacking a buzzard, a kite, a crow, or an eagle, is one of the most amusing spectacles. One feels that they are sure of victory, and one sees the anger of the bird of prey. In such circumstances they perfectly support one another, and their courage grows with their numbers."(19) The lapwing has well merited the name of a "good mother" which the Greeks gave to it, for it never fails to protect other aquatic birds from the attacks of their enemies. But even the little white wagtails (Motacilla alba), whom we well know in our gardens and whose whole length hardly attains eight inches, compel the sparrow-hawk to abandon its hunt. "I often admired their courage and agility," the old Brehm wrote, "and I am persuaded that the falcon alone is capable of capturing any of them. … When a band of wagtails has compelled a bird of prey to retreat, they make the air resound with their triumphant cries, and after that they separate." They thus come together for the special purpose of giving chase to their enemy, just as we see it when the whole bird-population of a forest has been raised by the news that a nocturnal bird has made its appearance during the day, and all together—birds of prey and small inoffensive singers—set to chase the stranger and make it return to its concealment.

      What an immense difference between the force of a kite, a СКАЧАТЬ