The great winter flocks of crows going to and from their roosting places to the feeding grounds are common sights. I have witnessed some remarkable flights of hawks when for several consecutive days individuals of many species drifted lazily by, scores being constantly in sight. I have known the short-eared owls to gather in large companies. Blind indeed is he who has not viewed with wonder the migrations of the birds in spring and fall. Who has not awakened some spring morning to find the fields and woods full of a variety of birds of which a day before only a few could be found? Who has not been thrilled by the melody of the bobolink or admired the formal columns of the geese? These migrating groups are often of very distinct species. Eight kites, one crane and one peregrine falcon are reported as forming one motley group.

It must not be thought that these are always chance associations. There are many illustrations of a definite purpose. Pelicans "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 the fish that happen to be inclosed 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." 13 Hunting parties of animals are well known. Monkeys combine to get food. Brazilian kites are said to summon assistance if the prey is too large. Kingbirds frequently combine to chase a crow or hawk. If a burying beetle discovers a dead mouse it summons from four to ten others to help. Crabs have 13 KROPOTKIN, P. o. c., p. 23.

been known to work for hours to try to help a comrade that had been put on its back.

In our climate birds scatter somewhat during the mating season. Later, flocks of young birds may be seen gaining strength by many flights ere they join in larger and larger companies for the southward journey which takes many of them even to South America. There must be some advantage in these associations. Our prairie dogs might live so far as conditions are concerned scattered over the plains; instead they live in great villages. Possibly this lies in the strength of numbers and the better chances of protection. Many birds such as cranes or parrots post sentries while the flock is feeding or send out spies to make sure no enemy is about; they live, save during the breeding season, in flocks; they have common roosting places; they combine against enemies. As a result, they reach a considerable age and have few large enemies save man.

The great power gotten by bees and ants as a result of their social habits and division of labor is often described. Observers in Africa tell of the warlike ants driving all animals before them on their marches.

Now it is to be noted that among those of any given species there is little direct competition but rather vast coöperation. The warning against common enemies; the care, often the joint care of the young; the many efforts to assist the injured and the combination to fight the intruder are all opposed to purely selfish considerations. Save where sex enters in they rarely fight each other. No wonder then that Kropotkin writes after viewing these animal societies: "As seen from the above, the war of each against all is not the law of nature. Mutual aid is as much a law as mutual struggle." 14 Or again: "Don't 14 KROPOTKIN, P. o. c., p. 22.

compete!-competition is always injurious to the species, and you have plenty of resources to avoid it.'... That is the watchword which comes to us from the bush, the forest, the river, the ocean. 'Therefore combine

practice mutual aid.' . . . . . That is what Nature teaches us, and that is what all those animals which have attained the highest positions in their respective classes have done." 15

There are, to be sure, illustrations of solitary specimens of social animals — rogue buffalo, rogue elephant — which seem to have been driven out of their groups. There are some animals among the carnivora which seldom associate save in very small groups. There are a few like the gorilla rarely seen save in family associations or alone. These are extremely exceptional and perchance are but the few survivors of groups once gregarious. From fish or insects, through the great bird and mammalian groups, to man himself, association and the resulting coöperation are well nigh universal.

There is another side to the picture more striking and spectacular, hence better known. Inasmuch as it is one of the functions of life to furnish food to other forms and inasmuch as the willingness to be eaten is seldom synchronous with the hunger of the eater, there is a constant warfare. Strength, cunning, fleetness of wing or foot or the maintenance of group life may enable the individual to survive. Sooner or later there is likely to come the accident or sickness, the weakness following absence of food, the moment of inattention and the enemy has done his work. It may be true that the great bulk of lives lost are those of the young and untrained; it may be that sudden temperature changes may reduce thousands to 15 KROPOTKIN, P. o. c., p. 75.

scores; but it still remains true that the destruction by other types of life is in addition to that wrought by physical changes. The combined results. are enormous. Natural death, in the sense we use the term (death from old age), is the least common form in the animal world. Well may Roosevelt say: "Civilized man now usually passes his life under conditions which eliminate the intensity of terror felt by his ancestors when death by violence was their normal end, and threatened them during every hour of the day and night. It is only in nightmares that the average dweller in civilized countries now undergoes the hideous horror which was the regular and frequent portion of his ages-vanished forefathers, and which is still an everyday incident in the lives of most wild crea

tures.

"Death by violence, death by cold, death by starvation

these are the normal endings of the stately and beautiful creatures of the wilderness. The sentimentalists who prattle about the peaceful life of nature do not realize its utter mercilessness; although all they would have to do would be to look at the birds in the winter's woods, or even at the insects on a cold morning or cold evening." 16

On the whole, the lowest forms of life reproduce most rapidly, the highest the most slowly. The cholera bacillus can divide every twenty minutes, and might thus in one day become 5,000,000,000,000,000,000,000 with an estimated weight of about 7,366 tons. An annual plant with only two seeds would be represented by 1,048,576 in the twenty-first year. The descendants of a pair of house flies from April to November might amount to 214,577,844,320,000,000,000,000, while the young of a single pair of 16 ROOSEVELT, T. African Game Trails, pp. 200-201.

mosquitoes in 180 days would be represented by the figure 2 at the left of one of these lines followed by a full row of ciphers. A pair of robins having four young each season and these reproducing in like measure would have some 20,913,948,846 descendants at the end of twenty years. The slowest breeder known, the elephant, if given a life of 100 years with an average of ten offspring which reproduced equally would have some 19,000,000 descendants in 150 years. Now, in actual life, no such reproduc

tion takes place. We must recognize then the rapid possible increase, theoretically speaking, of the individual organism and also the relatively fixed total aggregate of any species. "If all the feeders on vegetable life were allowed to develop absolutely without check during two successive years, the first of them would see every green thing swept from the face of the earth, and the second would destroy all possibility of the future recurrence of fully 90 per cent of all the existing plants. Under normal conditions, and in the long run, one pair of moths, producing say 500 eggs, are represented next year by another pair of the same species, and no more: that is, out of 500 eggs, producing 500 caterpillars, 498 are destroyed in some way. . . . The important thing is that a species abundant in number of specimens has become so in spite of the combination of all its natural checks and, conditions remaining equal, will maintain itself in the same ratio, just as a rare species barely maintains itself against the combination opposing it." 17 These checks are weather, disease, animals, birds and predatory and parasitic insects. "In this way it happens that after a season of grasshopper abundance a season of blister beetle 17 SMITH, J. B. Our Insect Friends and Enemies, pp. 84-85.