Mutual Aid: A Factor of Evolution

= Catalogue raisonn'e des oiseaux de la faune pontiqtie, in D^midoff! 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." ^

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 dis- played 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

Voyage ; abstracts in Brehm, iii. 360. During their migrations birds of prey often associate. One flock, which H. Seebohm saw crossing the Pyrenees, represented a curious assemblage of " eight kites, one crane, and a peregrine falcon" (The Birds of Siberia, 1901, p. 417)- 1 Birds in the Northern Shires, p. 207. from forty to fifty thousand individuals, part of which enjoy sleep while the others keep watch, and others again go fishing.^ 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." 2 True, the sparrows are extremely particular in keeping their domains free from the invasions of strangers ; thus the sparrows of the Jardin du Luxem- bourg 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 1 Max. Perty, UeUr das Seeknkben der Thieve (Leipzig, 1876) pn 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 Buphagus — the sea-hen of the sealers — pursue gulls to 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.^ 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. ^ The lap- wing 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

1 Dr. Elliot Coues, Birds of the Kerguelen Island, in Smithsonian Miscellaneous Collections, vol. xiii. No. 2, p. 11. 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 buzzard or a hawk, and such small birds as the meadow-wagtail ; and yet these little birds, by their cornmon action and courage, prove superior to the powerfully-winged and armed robbers ! In Europe, the wagtails not only chase the birds of prey which might be dangerous to them, but they chase also the fishing-hawk "rather for fun than for doing it any harm;" while in India, according to Dr. Jerdon's testimony, the jackdaws chase the gowinda-kite " for simple matter of amusement." Prince Wied saw the Brazilian eagle urubitinga surrounded by numberless flocks of toucans and cassiques (a bird nearly akin to our rook), which mocked it. " The eagle," he adds, "usually supports these insults very quietly, but from time to time it will catch one of these mockers." In all such cases the little birds, though very much inferior in force to the bird of prey, prove superior to it by their common action.^

1 As to the house-sparrows, a New Zealand observer, Mr. T. W. However, the most striking effects of common life for the security of the individual, for its enjoyment of life, and for the development of its intellectual capacities, are seen in two great families of birds, the cranes and the parrots. The cranes are extremely sociable and live in most excellent relations, not only with their congeners, but also with most aquatic birds. Their prudence is really astonishing, so also their intelligence ; they grasp the new conditions in a moment, and act accordingly. Their sentries always keep watch around a flock which is feeding or resting, and the hunters know well how difficult it is to approach them. If man has succeeded in surprising them, they will never return to the same place without having sent out one single scout first, and a party of scouts afterwards ; and when the reconnoitring party returns and reports that there is no danger, a second group of scouts is sent out to verify the first report, before the whole band moves. With kindred species the cranes contract real friendship ; and in captivity there is no bird, save the also sociable and highly- intelligent parrot, which enters into such real friend- ship with nian. " It sees in man, not a master, but a friend, and endeavours to manifest it," Brehm concludes from a wide personal experience. The

Kirk, described as follows the attack of these " impudent " birds upon an " unfortunate " hawk : — " He heard one day a most unusual noise, as though all the small birds of the country had joined in one grand quarrel Looking up, he saw a large hawk (C. gouldi- — a carrion feeder) being buffeted by a flock of sparrows. They kept dashing at him in scores, and from all points at once. The unfortun- ate hawk was quite powerless. At last, approaching some scrub, the hawk dashed into it and remained there, while the sparrows congregated in groups round the bush, keeping up a constant chatter- ing and noise " (Paper read before the New Zealand Institute ; Nature, Oct. 10, 1891).

crane is in continual activity from early in the morn- ing till late in the night ; but it gives a few hours only in the morning to the task of searching its food, chiefly vegetable. All the remainder of the day is given to society life. "It picks up small pieces of wood or small stones, throws them in the air and tries to catch them ; it bends its neck, opens its wings, dances, jumps, runs about, and tries to manifest by all means its good disposition of mind, and always it remains graceful and beautiful." ^ As it lives in society it has almost no enemies, and thougji Brehm occasionally saw one of them captured by a crocodile, he wrote that except the crocodile he knew no enemies of the crane. It eschews all of them by its proverbial prudence ; and it attains^ as a rule, a very old age. No wonder that for the maintenance of the species the crane need not rear a numerous offspring ; it usually hatches but two eggs. As to its superior intelligence, it is sufficient to say that all observers are unanimous in recognizing that its intel- lectual capacities remind one very much of those of man.

The other extremely sociable bird, the parrot, stands, as known, at the very top of the whole feathered world for the development of its intelligence. Brehm has so admirably summed up the manners of life of the parrot, that I cannot do better than translate the following sentence : — "Except in the pairing season, they live in very numerous societies or bands. They choose a place in the forest to stay there, and thence they start every morning for their hunting expeditions. The members of each band remain faithfully attached to each other, and they share in common good or

bad luck. All together they repair in the morning to a field, or to a garden, or to a tree, to feed upon fruits. They post sentries to keep watch over the safety of the whole band, and are attentive to their warnings. In case of danger, all take to flight, mutually supporting each other, and all simul- taneously return to their resting-place. In a word, they 'always live closely united." They enjoy society of other birds as well. In India, the jays and crows come together from many miles round, to spend the night in company with the parrots in the bamboo thickets. When the parrots start hunting, they display the most wonderful intelli- gence, prudence, and capacity of coping with circum- stan^s. Take, for instance, a band of white cacadoos in Australia. Before starting to plunder a corn-field, they first send out a reconnoitring party which occu- pies the highest trees in the vicinity of the field, while other scouts perch upon the intermediate trees between the field and the forest and transmit the signals. If the report runs " All right," a score of cacadoos will separate from the bulk of the band, take a flight in the air, and then fly towards the trees nearest to the field. They also will scrutinize the neighbourhood for a long while, and only then will they give the signal for general advance, after which the whole band starts at once and plunders the field in no time. The Australian settlers have the greatest difficulties in beguiling the prudence of the parrots ; but if man, with all his art and weapons, has succeeded in killing some of them, the cacadoos become so prudent and watchful that they henceforward baffle all stratagems.^

There can be no doubt that it is the practice of life in society which enables the parrots to attain that very high level of almost human intelligence and almost human feelings which we know in them. Their high intelligence has induced the best naturalists to describe some species, namely the grey parrot, as the " bird- man." As to their mutual attachment it is known that when a parrot has been killed by a hunter, the others fly over the corpse of their comrade with shrieks of complaints and " themselves fall the victims of their friendship," as Audubon said ; and when two captive parrots, though belonging to two different species, have contracted mutual friendship, the accidental death of one of the two friends has sometimes been followed by the death from grief and sorrow of the other friend. It is no less evident that in their societies they find infinitely more protection than they possibly might find in any ideal development of beak and claw. Very few birds of prey or mammals dare attack any but the smaller species of parrots, and Brehm is absolutely right in saying of the parrots, as he also says of the cranes and the sociable monkeys, that they hardly have any enemies besides men ; and he adds : " It is most probable that the larger parrots succumb chiefly to old age rather than die from the claws of any enemies." Only man, owing to his still more superior intelligence and weapons, also derived from association, succeeds in partially destroying them. Their very longevity would thus appear as a result of their social life. Could we not say the same as regards their wonderful memory, which also must be favoured in its development by society-life and by longevity accompanied by a full enjoyment of bodily and mental faculties till a very old age ?

As seen from the above, the war of each against all is not the law of nature. Mutual aid is as much a law of nature as mutual struggle, and that law will become still more apparent when we have analyzed some other associations of birds and those of the mammalia. A few hints as to the importance of the law of mutual aid for the evolution of the animal kingdom have already been given in the preceding pages ; but their purport will still better appear when, after having given a few more illustrations, we shall be enabled presently to draw therefrom our conclusions.

Migrations of birds. — Breeding associations. — Autumn societies. — Mammals : small number of unsociable species. — Hunting associa- tions of wolves, lions, etc. — Societies of rodents; of ruminants; of monkeys. — Mutual Aid in the struggle for life. — Darwin's argu- ments to prove the struggle for life within the species. — Natural checks to over-multiplication. — Supposed extermination of interme- diate links. — Elimination of competition in Nature.

As soon as spring comes back to the temperate zone, myriads and myriads of birds which are scattered over the warmer regions of the South come together in numberiess bands, and, full of vigour and joy, hasten northwards to rear their offspring. Each of our hedges, each grove, each ocean cliff, and each of the lakes and ponds with which Northern America, Northern Europe, and Northern Asia are dotted tell us at that time of the year the tale of what mutual aid means for the birds ; what force, energy, and protection it confers to every living being, however feeble and defenceless it otherwise might be. Take, for instance, one of the numberless lakes of the Russian and Siberian Steppes. Its shores are peopled with myriads of aquatic birds, belonging to at least a score of different species, all living in perfect peace— all '< protecting one another.

" For several hundred yards from the shore the air is filled with gulls and terns, as with snow-flakes on a winter day. Thousands of plovers and sand-coursers run over the beach, searching their food, whistling, and simply enjoying life. Further on, on almost each wave, a duck is rocking, while higher up you notice the flocks of the Casarki ducks. Exuberant life swarms every where." ^ And here are the robbers — the strongest, the most cunning ones, those "ideally organized for robbery." And you hear their hungry, angry, dismal cries as for hours in succession they watch the opportunity of snatching from this mass of living beings one single unprotected individual. But as soon as they approach, their presence is signalled by dozens of voluntary sentries, and hundreds of gulls and terns set to chase the robber. Maddened by hunger, the robber soon abandons his usual precautions : he suddenly dashes into the living mass ; but, attacked from all sides, he again is compelled to retreat. From sheer despair he falls upon the wild ducks ; but the intelligent, social birds rapidly gather in a flock and fly away if the robber is an erne ; they plunge into the lake if it is a falcon ; or they raise a cloud of water-dust and bewilder the assailant if it is a kite.^ And while life continues to swarm on the lake, the robber flies away with cries of anger, and looks out for carrion, or for a young bird or a field-mouse not yet used to obey in time the warnings of its comrades. In the face of an exuberant life, the ideally-armed robber must be satisfied with the off-fall of that life.

" you may sail along the coast for many miles and see all the ledges, all the cliffs and corners of the mountain-sides, up to a height of from two to five hundred feet, literally covered with sea-birds, whose white breasts show against the dark rocks as if the rocks were closely sprinkled with chalk specks. The air, near and far, is, so to say, full with fowls." ^ 1 The Arctic Voyages of A. E. Nordenskjbld, London, 1879, P- I3S- See also the powerful description of the St. Kilda Islands by Mr. Dixon (quoted by Seebohm), and nearly all books of Arctic travel.

variety itself, offering all possible varieties of characters, from the basest to the highest : and that is why she cannot be depicted by any sweeping assertion. Still less can she be judged from the moralist's point of view, because the views of the moralist are themselves a result — mostly unconscious — of the observation of Nature. 1 Coming together at nesting-time is so common with most birds that more examples are scarcely needed. Our trees are crowned with groups of crows' nests ; our hedges are full of nests of smaller birds ; our farmhouses give shelter to colonies of swallows ; our old towers are the refuge of hundreds of nocturnal birds ; and pages might be filled with the most charm- ing descriptions of the peace and harmony which prevail in almost all these nesting associations. As to the protection derived by the weakest birds from their unions, it is evident. That excellent observer. Dr. Coues, saw, for instance, the little cliff-swallows nesting in the immediate neighbourhood of the prairie falcon {Falco polyargus). The falcon had its nest on the top of one of the minarets of clay which are so common in the canons of Colorado, while a colony of swallows nested just beneath. The little peaceful birds had no fear of their rapacious neighbour ; they never let it approach to their colony. They immediately surrounded it and chased it, so that it had to make off at once. 2

^ Elliot Coues, in Bulletin U.S. Geol. Survey of Territories, iv. No. 7, pp. 556, 579, etc. Among the g\iX\s,-{Larus argentatus), Polyakoff saw on a marsh in Northern Russia, that the nesting- grounds of a very great number of these birds were always patrolled by one male, which warned the colony of the \ approach of danger. All birds rose in such case and attacked the enemy with great vigour. Life in societies does not cease when the nesting period is over; it begins then in a new form. The young broods gather in societies of youngsters, gener- ally including several species. Social life is practised at that time chiefly for its own sake — partly for security, but chiefly for the pleasures derived from it. So we see in our forests the societies formed by the young nuthatchers {Sitta ccesia), together with tit- mouses, chaffinches, wrens, tree-creepers, or some wood-peckers.i In Spain the swallow is met with in company with kestrels, fly-catchers, and even pigeons. In the Far West of America the young horned larks live in large societies, together with another lark (Sprague's), the skylark, the Savannah sparrow, and several species of buntings and longspurs.^ In fact, it would be much easier to describe the species which live isolated than to simply name those species which join the autumnal societies of young birds — not for hunting or nesting purposes, but simply to enjoy life in society and to spend their time in plays and sports, after having given a few hours every day to find their daily food.

The females, which had five or six nests together on each knoll of the marsh, kept a certain order in leaving their nests in search of food. The fledglings, which otherwise are extremely unprotected and easily become the prey of the rapacious birds, were never left alone (" Family Habits among the Aquatic Birds," in Proceedings of the Zool. Section of St. Petersburg Soc. of Nat., Dec. 17, 1874). 1 Brehm Father, quoted by A. Brehm, iv. 34 seq. See also White's Natural History of Selborne, Letter XI.

^ Dr. Coues, Birds of Dakota and Montana, in Bulletin U.S. Survey of Territories, iv. No. 7. bands scattered over a wide territory gather in thousands ; they come together at a given place, for several days in succession, before they start, and they evidently discuss the particulars of the journey. Some species will indulge every afternoon in flights prepara- tory to the long passage. All wait for their tardy congeners, and finally they start in a certain well- chosen direction — a fruit of accumulated collective experience — the strongest flying at the head of the band, and relieving one another in that difficult task. They cross the seas in large bands consisting of both big and small birds, and when they return next spring they repair to the same spot, and, in most cases, each of them takes possession of the very same nest which it had built or repaired the previous year.^

This -siihjprt J& so vast^^jQd^_y£L-Sfl-imfierJ[iectly studied ; it offers so many striking illustrations of 'mutual-aid habits, subsidiary to the main fact of migration — each of which would, however, require a special study — that I must refrain from entering here into more details. I can only cursorily refer to the numerous and animated gatherings of birds which take place, always on the same spot, before they begin their long journeys north or south, as also those which one sees in the north, after the birds have arrived at their breeding-places on the Yenisei or in the northern counties of England. For many days in

1 It has often been intimated that larger birds may occasionally transport some of the smaller birds when they cross together the Mediterranean, but the fact still remains doubtful. On the other side, it is certain that some smaller birds join the bigger ones for migration. The fact has been noticed several times, and it was recently confirmed by L. Buxbaum at Raunheim. He saw several parties of cranes which had larks flying in the midst and on both sides of their migratory columns {Der soologische Garten, 1886, p.

succession— sometimes one month^they will come together every morning for one hour, before flying in search of food — perhaps discussing the spot where they are going to build their nests.^ And if, during the migration, their columns are overtaken by a storm, birds of the most different species will be brought together by common misfortune. The birds which are not exactly migratory, but slowly move northwards and southwards with the seasons, also perform these peregrinations in flocks. So far from migrating isolately, in order to secure for each separate individual the advantages of better food or shelter which are to be found in another district — they always wait for each other, and gather in flocks, before they move north or south, in accordance with the season.^

Going now over to-mammals^the first thing which strikes us is the overwhelming tlumerical predominance of social species over those few carnivores which do not associate. The plateaus, the Alpine tracts, and the Steppes of the Old and New World are stocked with herds of deer, antelopes, gazelles, fallow deer, buffaloes, wild goats and sheep, all of which are sociable animals. When the Europeans came to settle in America, they found it so densely peopled with buffaloes, that pioneers had to stop their advance when a column of migrating buffaloes came to cross the route they followed ; the march past of the dense

2 The fact is well known to every field-naturalist, and with refer- ence to England several examples may be found in Charles Dixon's Among the Birds in Nortliern Shires. The chaffinches arrive during wmter m vast flocks; and about the same time, i.e. in November come flocks of bramblings ; redwings also frequent the same places "m similar large companies," and so on (pp. 165, 166). column lasting sometimes for two and three days. And when the Russians took possession of Siberia they found it so densely peopled with deer, antelopes, squirrels, and other sociable animals, that the very conquest of Siberia was nothing but a hunting expedi- tion which lasted for two hundred years ; while the grass plains of Eastern Africa are still covered with herds composed of zebra, the hartebeest, and other antelopes.

Not long ago the small streams of Northern America and Northern Siberia were peopled with colonies of beavers, and up to the seventeenth century like colonies swarmed in Northern Russia. The flat lands of the four great continents are still covered with countless colonies of mice, ground-squirrels, marmots, and other rodents. In the lower latitudes of Asia and Africa the forests are still the abode of numerous families of elephants, rhinoceroses, and numberless societies of monkeys. In the far north the reindeer aggregate in numberless herds ; while still further north we find the herds of the musk-oxen and number- less bands of polar foxes. The coasts of the ocean are enlivened by flocks of seals and morses ; its waters, by shoals of sociable cetaceans ; and even in the depths of the great plateau of Central Asia we find herds of wild horses, wild donkeys, wild camels, and wild sheep. All these mammals live in societies and nations sometimes numbering hundreds of thousands of individuals, although now, after three centuries of gunpowder civilization, we find, but the ddbris of the immense aggregations of old. How trifling, in com- parison with them, are the numbers of the carnivores ! And how false, therefore, is the view of those who speak of the animal world as if nothing were to be

seen in it but lions and hyenas plunging their bleeding teeth into the flesh of their victims! One might as well imagine that the whole of human life is nothing but a succession of war massacres. Association and mutual aid arejhe_rulejwith_ma^ mais. We find social habits even among the carni- vores, and we can only name the cat tribe (lions, tigers, leopards, etc.) as a division the members of which decidedly prefer isolation to society, and are but seldom met with even in small groups. And yet, even among lions "this is a very common practice to hunt in company." ^ The two tribes of the civets {ViverridcB) and the weasels [Mustelidce) might also be characterized by their isolated life, but it is a fact that during the last century the common weasel was more sociable than it is now ; it was seen then in larger groups in Scotland and in the Unterwalden canton of Switzerland. As to the great tribe of the dogs, it is eminently sociable, and association for hunting purposes may be considered as eminently characteristic of its numerous species. It is well known, in fact, that wolves gather in packs forJbunting, and Tschudi Tett an excellent descrip^tiqn of how they draw up in a half^^cffcle^ surround a cow which is grazing on a mountain slope, and then, suddenly appearing with a loud barking, make it roll in the abyss.2 Audubon, in the thirties, also saw the Labrador wolves hunting in packs, and one pack following a man to his cabin, and killing the dogs. During severe winters the packs of wolves grow so numerous as to become a danger for human settle- ments, as was the case in France some five-and-forty

years ago. In the Russian Steppes they never attack the horses otherwise than in packs ; and yet they have to sustain bitter fights, during which the horses (according to Kohl's testimony) sometimes assume offensive warfare, and in such cases, if the wolves do not retreat promptly, they run the risk of being surrounded by the horses and killed by their hoofs. The prairie- wolves (Cams latrans) are known to associate in bands of from twenty to thirty individuals when they chase a buffalo occasionally separated from its herd.^ Jackals, which are most courageous and may be considered as one of the most intelligent representatives of the dog tribe, always hunt in packs ; thus united, they have no fear of the bigger carnivores.^ As to the wild dogs of Asia (the Kholzuns, or Dholes), Williamson saw their large packs attacking all larger animals save elephants and rhinoceroses, and over- powering bears and tigers. Hyenas always live in societies and hunt in packs, and the hunting organiz- ations of the painted lycaons are highly praised by Gumming. Nay, even foxes, which, as a rule, live isolated in our civilized countries, have been seen combining for hunting purposes.^ As to the polar fox, it is — or rather was in Steller's time — one of the most sociable animals ; and when one reads Steller's descrip- tion of the war that was waged by Behring's un- fortunate crew against these intelligent small animals, one does not know what to wonder at most : the extraordinary intelligence of the foxes and the mutual aid they displayed in digging out food concealed under cairns, or stored upon a pillar (one fox would climb on

2 For their hunting associations see Sir E. Tennant's Natural History of Ceylon, quoted in Romanes's Animal Intelligence, p. 432. its top and throw the food to its comrades beneath), or the cruelty of man, driven to despair by the numer- ous packs of foxes. Even some bears live in societies where they are not disturbed by man. Thus Steller saw the black bear of Kamtchatka in numerous packs, and the polar bears are occasionally found in small groups. Even the unintelligent insectivores do not always disdain association.^