[44] Waterton, Wanderings in South America (First Journey), ch. iii.
Not only do animals thus feign death in order to secure their own safety, but the female sometimes endeavours to attract an enemy"s attention and feigns to be wounded in order to decoy him away from her young. This trick is adopted especially by birds. In ill.u.s.tration of this it will be sufficient to quote from Bendire"s Life Histories of North American Birds some observations by Mr. Ernest Thompson of Toronto, regarding the Canadian Ruffled Grouse (Bonasa umbellus togata), commonly called the Partridge by Canadians:--"Every field man must be acquainted with the simulation of lameness, by which many birds decoy or try todecoy intruders from their nests. This is an invariable device of the Partridge, and I have no doubt that it is quite successful with the natural foes of the bird; indeed it is often so with Man. A dog, as I have often seen, is certain to be misled and duped, and there is little doubt that a mink, skunk, rac.o.o.n, fox, coyote, or wolf would fare no better. Imagine the effects of the bird"s tactics on a prowling fox: he has scented her as she sits; he is almost upon her, but she has been watching him, and suddenly, with a loud "whirr," she springs up and tumbles a few yards before him. The suddenness and noise with which the bird appears cause the fox to be totally carried away; he forgets all his former experience, he never thinks of the eggs, his mind is filled with the thought of the wounded bird almost within his reach; a few more bounds and his meal will be secured. So he springs and springs, and very nearly catches her, and in his excitement he is led on, and away, till finally the bird flies off, leaving him a quarter of a mile or more from the nest.
"If instead of eggs the Partridge has chicks, she does not await the coming of the enemy, but runs to meet and mislead him ere yet he is in the neighbourhood of the brood; she then leads him far away, and returning by a circuitous route, gathers her young together again by her clucking. When surprised she utters a well-known danger-signal, a peculiar whine, whereupon the young ones hide under logs and among gra.s.s. Many persons say they will each seize a leaf in their beaks and then turn over on their backs. I have never found any support for this idea, although I have often seen one of the little creatures crawl under a dead leaf."[45]
[45] Bendire, Life Histories of North American Birds (Smithsonian Contributions to Knowledge, vol. xxviii.), 1892, p. 64.
Resistance in common by social animals.--If neither flight nor feint has saved an animal from the hunter, he naturally fights as long as he can, but this struggle in extremis is rarely crowned with success. Certain species, especially those which live in society, are able nevertheless, by uniting their efforts, to resist enemies who would easily triumph over them if they were isolated.
Among tribes of Apes mutual a.s.sistance, as described by Brehm, is common.
When by chance a bird of prey, such as an eagle, has thrown himself on a young ape who is amusing himself far from the maternal eye, the little one does not let himself be taken without resistance; he clings to the branches and utters shrill and despairing cries. His appeals are heard, and in an instant a dozen agilemales arrive to save him; they throw themselves on the imprudent ravisher and seize him, one by the claw, another by the neck, another by a wing, pulling him about and hara.s.sing him. The bird struggles as well as he can, distributing around him blows from talons and beak. But he is often strangled, and when his temerity does not receive this extreme punishment, the feathers which fall from him when he flies away bear witness that he has not emerged unscathed from the scuffle.
Animals like Buffaloes resist by a common defence the most terrible Carnivora.
Even the Tiger is their victim, although if one of them met that wild beast alone he would surely become its prey. Being very agile, the tiger can reach by one leap the back of the ruminant, whose brutal and ma.s.sive force cannot thus be exercised; but the feline who falls into the midst of a troop fares very badly. One buffalo falls on him with lowered horns, and with a robust blow of the head throws him into the air. The tiger cannot regain his senses, for as soon as he reaches the ground, and often even before, he is again seized and thrown towards other horns. Thus thrown from one to another like a ball, he is promptly put to death.
The less terrible Carnivora give Buffaloes no trouble. Wolves do not dare to attack them when they are united; they await in ambush the pa.s.sage of some strayed calf, and rapidly gain possession of it before the rest of the flock are aware, or they would dearly pay for their attack.
The Bisons of North America, near relatives of the Buffaloes, also repulse Wolves in common; and if Man succeeds better against them it is owing to the skill which he shows in hiding himself and not attracting their attention. Every one knows how Indians hunt the Bison with arrows, and his pursuit is very risky to the hunter, for he must not be discovered by the game, as he would then be trodden underfoot or disembowelled. In the immense prairies where these ruminants feed, a few Indians covered by bisons" skins advance on all fours, so that nothing betrays their presence. The victims fall one by one beneath silent blows, and their companions, who can see nothing suspicious in the neighbourhood, are not disturbed, supposing them, no doubt, to be peacefully resting.
It is not only against other animals that these great mammals have to defend themselves; they are much afraid of heat, and they are accustomed, especially in the south of Persia, to ruminate while lying in the water during the hot hours of the day. They only allow the end of the snout, or at most the head, to appear. It is a curious spectacle when fording a river to see emerge from the reeds the greatheads and calm eyes of the Buffaloes, who follow with astonishment all the movements of the hors.e.m.e.n, although nothing will disturb their sweet and fresh siesta.
But let us return to defences arranged in common. Horses are extremely sociable, and in the immense pampas of South America those who become wild again live in large troops. In difficult circ.u.mstances they help one another. If a great danger threatens them all the colts and mares a.s.semble together, and the stallions form a circle round the group, ready to drive back the a.s.sailant. But they do not accomplish this manoeuvre in the presence of an enemy of small importance. When a wolf appears on the plain all the males run after him, seeking to strike him with their feet and kill him, unless prompt flight delivers him from their blows.
The sociable humour of these horses makes them compa.s.sionate towards their fellows who are enslaved by man, and if a harnessed cart meets on its road a free band, it is a serious matter to the owner. They run up and surround the enslaved horse, saluting him with their cries and gambols, having the air of inviting him to throw his harness to the winds and follow them on the plain, where gra.s.s grows for all without work. Naturally the driver endeavours to preserve his n.o.ble conquest, and distributes blows with the whip to those who wish to debauch it. Then the wild horses become furious, and throw themselves on the vehicle; they break it with their feet and cut their comrade"s traces with their teeth to enable him to share their own free life. The enterprise satisfactorily concluded, they gallop away neighing in triumph.
It is owing to their union in large bands that Crows have so little to fear from diurnal birds of prey; if one approaches, they do not hesitate to throw themselves on him altogether. The Great Horn Owl, however, causes many ravages among them; for when asleep at night the Crow is without defence against the ravisher, for whom, on the contrary, obscurity is propitious. Thus they recognise him as a hereditary enemy, and never allow an opportunity of revenge to pa.s.s without profiting by it. If by chance an owl appears by day and one of them perceives him, immediately a clamour arises--a veritable cry of war; all those who are in the neighbourhood fly to the spot, and business ceases; the nocturnal bird of prey is a.s.saulted, riddled with blows from beaks, stunned, his feathers torn out, and, notwithstanding his defence, he succ.u.mbs to numbers.In all the preceding examples the social species unite for the common security the forces and effects which they can derive from their own organs.
I have spoken of the Apes and described how they defend themselves with their hands and teeth; but in certain cases they use weapons, employing foreign objects like a club or like projectiles.
Acts of this nature are considered to indicate a high degree of development, and it has often been repeated that they are the appanage of man alone; we have, however, seen the Toxotes, who, like all fishes, is not particularly intelligent, squirt water on to his victims. It is not easy to understand how a greater intellectual effort is required to throw a stone with the hand than to project water with the mouth. This is what the apes do, throwing on their a.s.sailants from the heights of trees everything which comes to hand: cocoa-nuts, hard fruits, fragments of wood, etc.
Baboons (Cynocephali) who usually live in the midst of rocks protect their retreat by rolling very heavy blocks on to their aggressors, or by forcibly throwing stones about the size of the fist. As these bands may contain from a hundred to one hundred and fifty individuals, it is a veritable hail of stones of all sizes which they roll down from the heights of the mountains where they find shelter.
Sentinels.--Not only do Apes know how to face danger or to avoid it by a prudent flight, but they also seek to foresee it, and to avoid exposing themselves to it. A troop of Apes, according to Brehm, generally places the leadership in the hands of a robust and experienced male. This primitive royalty is founded partly on the confidence inspired by an old chief, and partly by the fear inspired by his muscular arms and ferocious canine teeth. (Fig. 9.) He gives himself a great deal of trouble for the security of his subjects, and does not abuse the authority which he possesses. Always at the head, he leaps from branch to branch, and the band follows him. From time to time he scales a tall tree, and from its heights scrutinises the neighbourhood. If he discovers nothing suspicious a particular guttural grunt gives information to his companions. If, on the contrary, he perceives some danger he warns them by another cry, and all draw in ready to follow him in his retreat, which he directs in the same way as he guided the forward march.
Apes are not alone in relying on the experience of one of their members. Many other animals act in the same way: antelopes, gazelles, elephants, who advancein troops always conducted by an old male or female who knows all the forest paths, all the places favourable to pasture, and all the regions which must be avoided.
[Ill.u.s.tration: FIG. 9.]
Others, more democratic, instead of giving up the care of their safety to one individual, which cannot be done without abdicating some degree of individual independence, dispose around the place which they occupy a certain number of sentinels charged to watch over the common safety. This custom exists among prairie dogs, moufflons, crows, paroquets, and a great many other animals. The sentinels of the crows are not only always on the watch, but they are extremely discriminating; they do not give a warning at the wrong time. It is certain that these birds can distinguish a man armed with a gun from another who merely carries a stick, and they allow the second to approach much nearer than the first before giving the alarm.
Paroquets of all species live in joyous and noisy bands. After having pa.s.sed the night on the same tree they disperse in the neighbourhood, not without having first posted watchers here and there, and they are very attentive to their cries and indications.
The great Aras or Macaws, the large and handsome parrots of the Andes, act with much prudence when circ.u.mstances make it advisable, and they know when they ought to be on their guard. When they are in the depths of the forest, their own domain, they gather fruits in the midst of a deafening noise; each one squalls and cries according to his own humour. But if they have resolved to pillage a field of maize, as experience has taught them that these joyous manifestations would then be unseasonable and would not fail to attract the furious proprietor, they consummate the robbery in perfect silence. Sentinels are placed on the neighbouring trees. To the first warning a low cry responds; on the second, announcing a nearer danger, all the band fly away with vociferations which need no longer be restrained. The common Crane (Grus cinerea), still more far-seeing to avoid a possible future danger, despatches scouts who are thus distinct from sentinels who inform their fellows of present danger.[46]
[46] E. Poppig, Fragmenta zoologica itineris Chilensis, 1829-30.When these birds have been disturbed in any spot, they never return without great precautions. Before arriving, they stop; a few only go circ.u.mspectly forward, examining everything, and coming back to make their report. If this is not satisfactory the troop remains suspicious, sending new messengers. When they are at last a.s.sured that there is really nothing to fear, the rest follow.
Thus by the most varied methods animals endeavour to save their threatened lives, and succeed to some extent in attaining safety. Destruction and the chase on one side, conservation and flight on the other: these are the two chief acts which occupy living beings. Many, however, less threatened, succeed in perfecting their manner of life, and employ their industry in less pressing occupations than eating others or preventing others from eating them.CHAPTER IV.
PROVISIONS AND DOMESTIC ANIMALS.
PROVISIONS LAID UP FOR A SHORT PERIOD--PROVISIONS LAID UP FOR A LONG PERIOD--ANIMALS WHO CONSTRUCT BARNS--PHYSIOLOGICAL RESERVES--STAGES BETWEEN PHYSIOLOGICAL RESERVES AND PROVISIONS--ANIMALS WHO SUBMIT FOOD TO SPECIAL TREATMENT IN ORDER TO FACILITATE TRANSPORT--CARE BESTOWED ON HARVESTED PROVISIONS--AGRICULTURAL ANTS--GARDENING ANTS--DOMESTIC ANIMALS OF ANTS--DEGREES OF CIVILISATION IN THE SAME SPECIES OF ANTS--APHIS-PENS AND PADDOCKS--SLAVERY AMONG ANTS.
The industries of the chase which are derived immediately from the most imperious of needs--that of a.s.suring the existence of the individual--never arrive at a very extraordinary degree of perfection; or at all events, as they are indispensable to existence, we are not surprised at their development. It is unquestionable that an industry marks a higher degree of civilisation not only by its development, but still more by its reference to the less necessary things of life; in every species the importance of the place given to the superfluous is a mark of superiority. The animals who, foreseeing a hard season, or fearing the days when hunting will not be productive, lay up provisions to utilise in such times of famine, rise a degree higher than even the most skilful hunters. Not all ama.s.s with the same sagacity, and we shall find different examples of foresight, from the most rudimentary to the highest, very near what we may observe in Man.
The provisions harvested by animals have more than one destination: some are for the individual himself who has gathered them; others, on the contrary, are to serve as the food for his young at the age when they are not yet capable of seeking their own food. I will deal with these latter in another chapter, and propose at present only to speak of those animals who provision barns with the intention of themselves profiting by them.
The foresight of the animal is so much the greater the more remote the future for which he prepares. The Carnivora live from day to day and lay up no stores; it is the Rodents, certain frugivorous birds, and insects who exhibit the most complicated acts of economy.Provisions laid up for a short period.--As a rudimentary example of the art of preserving food in view of possible famine, I may mention the case of the Lanius collurio. I have already spoken of this bird and of his custom in days of abundance of spitting on thorns all the captures he has made. One may see side by side Coleoptera, crickets, gra.s.shoppers, frogs, and small birds. It is evident that these reserves cannot be preserved for more than a day, or at most two days. The bird ama.s.ses just enough to show us his apprehensions of the possible future lack of success in hunting, and his thought of preserving the surplus of the present in view of privations to come.[47]
[47] Naumann, Naturgeschichte der Vogel Deutschlands, etc.
The Fox, a very skilful hunter, has no trouble in finding game; of all the Carnivora he is, however, the only one who is truly foreseeing. The others in presence of abundant food gorge themselves, and abandon the rest at the risk of suffering to-morrow. The fox is not so careless. If he has had the good fortune to discover a poultry yard, well supplied but ill watched, he carries away as many fowls as he can before dawn and hides them in the neighbourhood of his burrow. He places each by itself, one at the foot of a hedge, another beneath a bush, a third in a hole rapidly hollowed out and closed up again. It is said that he thus scatters his treasures to avoid the risk of losing all at one stroke, although this prudence complicates his task when he needs to utilise his provisions. The fox, however, loses nothing, and knows very well where to find his stores. The very nature of the game prevents him from keeping it more than a few days.
Provisions laid up for a long period.--The Rodents, who live on dry fruits or grains, can on the other hand preserve them for a long time in their barns. The Squirrel, who may be seen all the summer leaping like a little madman from branch to branch, and who seems to have no cares except to exhibit his red fleece and show off his tail, is, contrary to appearance, a most sensible and methodical animal. He knows that winter is a hard time for poor beasts, and that fruits are then rare or hidden beneath the snow; in the autumn, therefore, when all the riches of the earth are abundant, and beech-nuts, acorns, and chestnuts have ripened, he harvests quant.i.ties of them and hides them wherever he can. Making use of the cavities he is acquainted with around his domain, hollow trees, holes that he makes in the earth beneath bushes, etc., he fills them with fruits, and when winter has come he extracts them to munch.Animals who construct barns.--The Field Rat of Hungary and Asia (Psammomys) gathers wheat during the summer. He cuts the blades and transports them to his home, where he stores them up in very considerable quant.i.ties; and during rigorous winters when famine appears also among men, gleaners of another species appear on the scene and seek for corn under the earth in the nests of the Psammomys. A single rat can store up more than a bushel. Those who are skilful in finding their holes can thus in a day glean a good harvest, to the detriment of the rats who are thus in their turn reduced to beggary.
The Hamster also makes provision of grain, but he introduces two improvements: the first at the harvest by only taking the edible part of the ear, and the second by constructing barns distinct from his home. Each possesses a burrow composed of a sleeping chamber, around which he has hollowed one or two others communicating with the first by pa.s.sages, and intended to serve as barns. The old and more experienced animals prepare even four or five of these storehouses. The end of summer is their season for work. They scatter themselves in the fields of barley or wheat, pull down the stalks of the cereals with their anterior paws, and then cut off the ear with their teeth. This done, they set about thrashing their wheat--that is to say, they separate the grain from the straw by turning the ear round and round between their paws. When the grains come out they pile them up in their cheeks, and thus transport them to one of the chambers already mentioned; they then return to exploit the field and continue these labours until they have completed the stores for winter.
A certain Vole (Arvicola economus) acts in much the same way as the Hamster, though he harvests a different cla.s.s of objects. It is not wheat which he collects but roots. He has to find these roots, to dig them up, to cut them into fragments of suitable dimensions for transport, and finally to pile them up in rooms disposed to receive them. This species, which inhabits Siberia, measures about twelve centimetres in length, but during summer and autumn Voles accomplish an amount of work which is surprising having regard to their size. The moment having arrived to think about winter, the Voles spread themselves about the steppe. Each hollows little pits around the roots he wishes to extract. After having bared them he cleans them while still in position, so as not to enc.u.mber his storehouses with useless earth. This preparatory labour having been completed, he divides the root into slices of a weight proportioned to his strength, and carries away the fragments one by one. Seizing each with his teeth, he walks backwards drawing it after him, and thus traverses a long road, crossing paths, going round tufts of gra.s.s or other obstacles, not letting himself be rebuffed by the difficultyand length of the task. Arrived at his hole, he enters this also backwards, drawing his burden through all his galleries. His dwelling, though the entrance is rather more complicated, resembles that of the Hamster. Like the latter, it is composed of a central room placed in communication with the outside by a maze of pa.s.sages, which cross one another. That is the sleeping-room, the walls of which are well formed, and which is carpeted with hay. From this various underground pa.s.sages start which lead to the storerooms, which are three or four in number. It is to these that the Vole bears his harvest. Each compartment is large enough to contain four or five kilogrammes of roots, so that the little rodent finds himself at the end of the season the proprietor of about fifteen kilogrammes of food in reserve. He would have enough to enable him to revel in abundance if he were able to reckon without his neighbours. This diligent animal has in fact one terrible parasite. This is Man, who will not allow him to enjoy in peace the fruits of his long labour and economy. In Siberia, a long and severe winter follows a very hot summer; in this season the inhabitants often lack provisions. A moment comes when they are glad to make up for want of bread by edible roots; but the search for these is long and troublesome, and should indeed have been thought of during summer. Man, during the fine weather less foreseeing than the rodent, does not hesitate when famine has come to turn to him for help. As he is the weaker, the Vole is obliged to submit to this vexatious tax. According to Pallas,[48] the inhabitants seek these nests full of provisions and dig them up.
The conqueror takes all he pleases, and abandons the rest to the unfortunate little beast, who, whether he likes it or not, has to be content. In this region the burrows of the Vole abound; therefore this singular t.i.the ensures a considerable revenue to those who levy it, as may be understood when we remember the extent of the stores ama.s.sed by the animal.
[48] Pallas, Ueber d. am Volgastrome bemerkten Wanderungen der grossen Wa.s.sermause (Arvicola amphibius), Nord--Beitr., vol. i., 1781, p. 335.
A Vole resembling the Arvicola arvalis, but larger, paler, and more rat-like, with large shining eyes and very short tail, overran in 1892-93 the cla.s.sic land of Thessaly, the land of Olympus, and the Vale of Tempe. It has always inhabited this region, and the old Greeks had an Apollo Smintheus, or Myoktonos, the Mouse-destroying G.o.d. "At the beginning of March," according to Prof. Loeffler, who has given an account of this invasion,[49] "the Voles were only beginning to troop from the slopes of the hills and the fallow-lands to the cultivated fields. It was frequently observed that they followed regular paths during their inroads.
Thus they advanced along the railway embankment. Their progress seemed tobe rather slow. Perhaps they do not advance further till the inhabitants of one of their strongholds or so-called castles have become too numerous. The runs which they excavate are at a depth of about twenty to thirty centimetres below the surface of the ground. The extent of their runs varies, and we found them extending in length from thirty to forty metres and more. These runs are connected with the surface by vertical holes of about five centimetres in diameter.
In many places four, five, and more holes have led to the same run. In such cases there is generally, not far off, an enlargement for the nest, lined with finely-ground vegetable material, where the young are produced and reared. In front of newly-opened holes the earth, which has been thrown far out, forms smooth hillocks. There were many well-defined and well-trodden paths on the ground, by which the Voles pa.s.s from one hole to another. They are never seen out of their holes by day, not even in places where the entire ground is riddled with holes like a sieve. They do not come out in search of food till the evening; even then not many are to be seen, but the peculiar squeaking noise they make is to be heard everywhere. Next day all sorts of freshly-severed plants are to be found in the holes. Stalks of corn they manipulate by standing on their hind legs and gnawing through the stalk; when this is bitten off they drag it into their holes to devour it there, sometimes making it smaller. They do their work with amazing rapidity. One evening a field was visited which was to be mowed next day, but when the labourers came in the morning they found nothing to cut. The Voles had destroyed the entire crop in a single night. A miller in the neighbourhood of Velestino reported that he went to his field early one morning, cut a measure of corn, loaded it on his a.s.s, and brought it to his mill. When he returned to his mill with a second load he found scarcely a vestige of the first remaining. Thinking it had been stolen he kept watch for the thief; but suddenly, to his great astonishment, hosts of Voles appeared and set to work to carry off the second load." Such facts as these recorded by Loeffler are by no means a merely recent phenomenon; Aristotle was familiar with the devastations of the Voles, and wrote that "some small farmers, having one day observed that their corn was ready for harvest, when they went the following day to cut their corn, found it all eaten."
Other ancient writers record similar facts.[50]
[49] Centralblatt f. Bak. u. Parasitenkunde, July 1892, and Zoologist, September 1892.
[50] Zoologist, May 1893. It may be added that the Scottish Vole, which was so destructive about the same time, does not burrow to a depth like the Thessaly Vole, but lives in shallow runs amongst the roots of herbage. Its exploits arerecorded in a Report on the Plague of Field-Mice in Scotland, made by a committee appointed by the President of the Board of Agriculture, 1893.
Two birds of North America, belonging to the Woodp.e.c.k.e.r family, prepare their provisions for the bad season with consummate art; not only do they harvest them and place them in shelter, but they arrange them in such a manner that at the right moment they can utilise them in the most convenient manner.
One of them which is common in California, the Melanerpes formicivorus, nourishes himself, as his name indicates, by insects, and especially ants. All the summer he gives himself up to this hunt, but at the same time he collects acorns, which he does not touch, however, so long as he can find other food. He ama.s.ses them in the following ingenious manner: he chooses a tree and hollows out in its trunk a cavity just capable of receiving one acorn. He then carries a fruit and introduces it forcibly into the hole he has just made. Thus buried, the acorn can neither fall nor become the prey of another animal. In the domain of these birds trees may be found which are riddled like a sieve with holes stopped up by an acorn as by a plug. When the hunting of insects ceases to be fruitful, the Melanerpes visits his barns. If an ordinary bird wished to eat one of these fruits, at each stroke of his beak, on account of the polish and convexity of the acorn"s surface, it would escape him, and only by a series of reiterated efforts would the interior be exposed; but for the American woodp.e.c.k.e.r the task is simplified; each acorn being maintained firmly in the bark, it is sufficient to break the envelope and the pulp is easily seized.[51]
[51] See, for instance, Nature, 20th July 1871; also A. L. Heermann, "Notes on the Birds of California," Journ. Acad. Nat. Sc. Philadelphia, 2nd Series, vol. ii., 1853, p. 259.
A relation of this bird, the Colaptes mexica.n.u.s, does not yield to him in economy and skill. He places his barn in the interior of a plant which is very abundant in the zone he inhabits. Insectivorous during a part of the year, he is forced to renounce this diet during the dry season. In the regions of Mexico where this bird is found the dry period is so absolute that he would die of hunger for want of insects or fruits if he had not taken the precaution of laying up stores during spring. His store consists of acorns. He has not time to fix them one by one, like the Melanerpes, and only thinks at first of rapidly collecting a large quant.i.ty. But it is in deciding the question as to where they are to be laid up that the Colaptes shows his remarkable intelligence. In the forests where he lives are to be foundaloes, yuccas, and agaves. When the agaves have flowered, the flower-bearing stem, two or three metres in length, shrivels, but remains standing for some time.
Its peripheral portion is hardened by the heat, while the sap in the interior almost entirely disappears. A hollow cylinder with a well-sheltered cavity is thus formed, and the Colaptes proposes to utilise it as a storehouse. His acorns will there be well protected against external influences and against the birds whose beaks are too weak to pierce the agave. It is then a question of filling the tube. The animal first pierces the wall towards the base of the stalk; through this hole he introduces acorns until he has filled the lower part of the cavity. This done, he makes a new hole rather above the first, and fills the interval between the two, continuing this process until he has arrived at the top of the stalk and filled the whole interior.
(Figs. 10 and 11.) The bird seems at first to take unnecessary trouble by boring so many holes. He would reach his end as well, it would seem, by making a single hole at the top to fill his storehouse, and another at the bottom to empty it.
But we must not thus accuse him of lack of judgment. The interior of the tube is just large enough for the pa.s.sage of an acorn; but at certain points the sap is not entirely absorbed, and there might easily be an impediment which would leave a large part of the cavity empty. Hence the necessity for a number of openings.
When the sun has scorched up plants, and provisions are rare, he turns to his barns of abundance. Now and every time that he has need he can utilise the method that has been employed by his cousin the Melanerpes. In order to feed on each acorn without too much trouble, or allowing it to slip from his beak, the bird places it in a vice. He hollows a hole in the trunk of a tree, introduces the fruit there forcibly, and eats it at his ease.[52]
[52] Henri de Saussure, "Observations sur les moeurs de divers oiseaux du Mexique," Arch. Sci. phys. et natur., 1859, pp. 21-41.
[Ill.u.s.tration: FIG. 10.]
[Ill.u.s.tration: FIG. 11.]
The provisions collected by these two birds reveal a remarkable fact. They possess indeed two distinct diets; they do not preserve for the period of famine the overplus of the foods which they consume in the period of abundance. They chase insects and feed on them as long as they can find them, while they gather up in their storehouses an entirely different food.Physiological reserves.--All the animals of which I have just spoken place their provisions for the future in barns in the same manner as Man. Those who have not this foresight are either able to nourish themselves in all seasons by the chase, or else, after having feasted one half of the year, they fast during the other half. In the latter case they consume during the fasting period a portion of their own substance, and use up materials placed in reserve in their organism, in the form of fat for example. This arrangement, which allows them to prolong life, though growing thin, until the next season of prosperity, is not under the control of the will. It is a complication of physiological phenomena resulting from the functioning of different parts of the organism.
Stages between physiological reserves and provisions.--Between physiological reserves and industrial stores we may place as an intermediate stage the interesting case of the Honey Ants.[53]
[53] H. C. McCook, The Honey Ants of the Garden of the G.o.ds, and the Ants of the American Plains, Philadelphia, 1882.
[Ill.u.s.tration: FIG. 12.]
[Ill.u.s.tration: FIG. 13.]
These insects (Myrmecocystus) live in Texas, and form colonies in which certain individuals play a very special part They exaggerate to an extreme point the power of preserving provisions in their crops. These materials are not a.s.similated; they do not form part of the animal"s body, and although placed inside it cannot be compared to physiological reserves. It is especially curious that they are not to be utilised only by the animal itself, but also by the other members of the colony who are not able to form such stores. Among the Myrmecocystus there are workers of two sorts; the first kind resemble other ants with some differences of detail, and build and hollow the earth nest which shelters the community. The second kind is quite different; the abdomen in these workers is enormously distended so as to const.i.tute a voluminous sphere, which may become four or five times larger than the thorax and head together. (Fig.
12.) On this distended receptacle appear several darker plates; these are the remains of the chitinous parts of the primitive wings. In the fine season these ants go out in a band and collect a sweet liquor which forms pearly drops on certain galls of oak leaves. These drops, elaborated into honey, gradually fill the crop, distending it and pushing back neighbouring organs until it receives its globularform. When they have arrived at this obese condition, the heavy honey ants no longer leave the nest. They remain without movement, hanging by their legs to the roof or lying against the walls of a room. The workers who have remained slender come and go, attending to their usual occupations, and pa.s.s near the others without paying attention to them or going out of the way to lend a.s.sistance to their impotent sisters when one of them has rolled over on the ground and can no longer arise unaided. (Fig. 13.) They only cease to be indifferent when impelled by the selfish sentiment of hunger, and then it is to ask and not to give a.s.sistance. The fat ants in fact could not themselves consume all the honey that they have elaborated; the others in times of famine approach them, caress them with their antennae, and obtain by solicitation a drop of honey which the large ones disgorge from the crop. Here, then, is a colony in which the division of labour has reached a remarkable degree of polymorphism. Some of the members accomplish the work of engineers and masons, while the others fabricate for the community a store of honey. Instead of depositing these provisions in cells like bees, they preserve them in their own digestive tube. This custom has re-acted to such an extent on the form of their bodies that at first sight they seem to belong to a different species.
[Ill.u.s.tration: FIG. 14.]
Animals who submit foods to special preparation in order to facilitate transport.--Not content with collecting materials as they are found in nature, certain animals submit them to preparation with various aims, either to render transport easier or that they may not deteriorate when stored. Among those of whom I have just spoken, some collect with the view of utilising their stores in a more remote future than others. The Ateucus sacer intends to consume the provisions he prepares almost immediately. Yet he acts in so careful a manner that I cannot pa.s.s him in silence. This beetle is the sacred Scarabaeus so venerated by the Egyptians, who have everywhere reproduced his image in porphyry and granite. He is a most singular insect. The celebrated Fabre has given a complete and very picturesque history of his customs.[54] I have myself had an opportunity of seeing him at work. It was in Persia, in the plain of Susiana, on a hot morning in March. We had pa.s.sed the night in the open air, proposing to continue our journey in the early morning, but our mules, rendered rather lively by the fresh gra.s.s brought out by the spring weather, had decided otherwise. They had all decamped to take a ramble on their own account. In order to pa.s.s away the hours taken up by the muleteers in searching for the strayed animals, the Scarabaeus would, I thought, furnish me with an amusing and instructivespectacle. During the night the mules had not failed to leave here and there the relics of their digestion. The aroma, borne on the morning breeze, had struck the Scarabaeus on awaking. It was his favourite dish. From all points of the sky their heavy silhouettes could be seen against the blue. It was still fresh, the sun having only risen about an hour before; the heat would soon become oppressive, and the sybaritic beetle, without attending to his morning appet.i.te, which his fresh meal could not fail to excite, nourishes the bourgeois dream of making his little pile in order to enjoy himself sheltered from the hot rays. Immediately on arriving on the scene of the accident each began to display feverish activity. All set to work. With their heads, the anterior edge of which is flat and supplied with six strong spines, they raised their provisions; with their anterior feet, which are large and also armed with spines, they moulded the paste and placed it beneath the abdomen between the four other legs, giving it a rounded form. Little by little the sphere increased and acquired the size of a small apple. That was sufficiently large, and besides it was already becoming hot. The insect set about carting away his prize to a sheltered dining-room. He placed his four posterior legs on the ball; with the two last, which were continually moving, he made certain of the equilibrium of the ma.s.s; then resting his head and two anterior feet on the ground he pushed backwards, and with extreme rapidity. (Fig. 14.) There was enough for all; each worker could find the just reward for his labour; I witnessed none of the regrettable facts narrated by Fabre. It happens sometimes, according to this ingenious observer, that a cunning Scarabaeus, who has taken no part in the laborious labour of moulding the paste, arrives when it is on the road to aid the convoy, or even simply to pretend to help, in order that when the moment has come he may claim a share in the coveted meal, or even carry it all away if he can profit by a momentary inattention on the part of the lawful proprietor. I followed one of these Coleoptera for more than five metres from the place where his labour began. After having deposited his ball he began to dig up the earth around it;[55] but the mules had returned and I was obliged to depart.
[54] J. H. Fabre, Souvenirs entomologiques, 1879.
[55] In captivity also, as Mrs. Brightwen found, the Scarabaeus always attempts to bury its ball in the earth.
I have no doubt that subsequent events were not exactly the same as narrated by Fabre for the Scarabaeus of Provence. The insect having made his hole, buries himself in it for a tete a tete with the precious sphere. He immediately sets about pa.s.sing the whole through his body. Without haste but without rest, for a week ora fortnight, as long as there is any of it left, he eats continuously, and continuously digests. He does not stop for a moment, his jaws are working the whole time; and Fabre has called attention to the fact that from the opposite extremity of the animal a continuous thread emerges without breaking, and becomes coiled up.
Care bestowed on harvested provisions.--Among the animals who take particular care of the provisions they have ama.s.sed, special mention must be made of certain species of Ants. It was formerly believed that these industrious Hymenoptera are not accustomed to store up in barns for the winter. This opinion long prevailed owing to the authority of Huber, so competent in these matters, although the ancients were well acquainted with the storehouses of ants.[56] But it was founded on an exclusive study of these insects in northern countries, in which, during the cold season, they become torpid and buried in their hybernal sleep. Naturally they have no need of food during this period, but it was incorrect to generalise from this fact. The ants of the south are active all the year round. An English naturalist, Moggridge, who pa.s.sed several winters at Mentone, has placed this fact out of doubt. Suffering from an incurable disease, he occupied the last years of his life in observing and setting down for the instruction of others the habits of these insects. He found that ants of the species Atta barbara store up grains. They utilise plants of various kinds, but usually fumitory, oats, nettle, various species of Veronica, etc. They procure these grains towards the end of autumn, collecting them on the soil, or even, when they do not fall in sufficient quant.i.ties, climbing up the plants and gathering them in position. An ant will, for instance, ascend the stem of a fruiting plant, of shepherd"s-purse, let us say, and select a well-filled but green pod, mid-way up the stem, those below being ready to shed their seeds at a touch. Then seizing it in its jaws, and fixing its hind legs firmly as a pivot, it contrives to turn round and round, and so to strain the fibres of the fruit-stalk until they snap; it then patiently backs down the stem. Sometimes two ants combine their efforts; one, at the base of the peduncle, gnaws at the point of greatest tension, while the other hauls upon it and twists it. And sometimes the ants drop the capsules to their companions below, corresponding with the curious account given by aelian of the way the spikelets of corn are thrown down "to the people below." In this labour they display the activity usual in their race, and do not stop until they have carried away to their barns the amount of provision they desire. When their wealth is stored up in the nest, the ants pile up the grains in some hundred little rooms designed for this purpose, each measuring from seven to eight centimetres in diameter, and three or four in height; the average granary being about the size of a gentleman"s gold watch.Adding up the quant.i.ties of grain divided between these different barns, it is found that they may be estimated at about 500 or 600 grammes, which represents a very large number of meals for such small appet.i.tes, and must cost colossal labour if we take into consideration the size of the workers. But when the harvest is completed, the Atta barbara have not completed their task; they are too ingenious to limit themselves to waiting with crossed legs for the moment to come when they may enjoy their labour, without considering the damage that may arise. Their first care is to prevent the grains from germinating for some weeks.
How they obtain this result is not exactly known, but it is certain that germination does not take place, although all the conditions of heat and moisture offered by the interior of the ant-hill are favourable to it; it is not less certain that this arrest is due to the ants. This is shown in a very simple manner. It is sufficient to prevent the access of the insects to one of these chambers to cause the grains to germinate immediately. We can only suppose some direct action of the ants, every other hypothesis falling before this single fact: the arrested phenomenon is produced as soon as the Atta barbara no longer acts on it. Therefore they arrest germination without rendering it impossible, and when the moment arrives for utilising the acc.u.mulated stores, their first care is to allow the grains to follow the normal course of evolution. The envelope breaks, the little plant makes its appearance; radicle and stalk come to light. But the ants do not permit the development to go too far. The little plant, in order to grow, digests the starch which is a.s.sociated with the alb.u.men, for it is not yet able to draw its nourishment direct from the soil. To be absorbed and a.s.similated this starch must first be transformed into sugar. This chemical transformation being effected, the grain is in the condition in which the ants prefer it. Like a wine-grower who watches over the fermentation in his vat, and stops it before the wine turns sour, they stop the digestion of the starch at this stage. If we do not know how they r.e.t.a.r.d germination, we know at all events how they render it impossible at this later stage. It is the young plant which absorbs the glucose, and which must therefore be destroyed; they cut off the radicle with their mandibles, and gnaw the stalk; the germ is thus suppressed. They have not yet finished their manipulations, which must enable them to preserve without further alteration the provisions which they have already rendered palatable. They bring out all their provisions to the sun, dry them, and take them back to the barns. As long as winter lasts they feed on this sweet flour. An anatomical peculiarity enables them to make the most of it; their mouth is so arranged that they can absorb solid particles and eat the alb.u.minous powder. In this they differ from their northern kin, who are obliged to feed exclusively on juices.[56] See chapter on "The Ancient Belief in Harvesting Ants," in McCook"s Agricultural Ants.
I have compared the labours of these ants to those of the wine-grower. Both of them in fact utilise the chemical phenomena going on in living matter; both of them know how at a given moment to prevent the transformation from going further. Neither of them for the rest take into account the part played by diastasis and ferments. The ancestors of one as of the other have by chance found out the method, and they transmit it from generation to generation.[57]
[57] J. Treherne Moggridge, Harvesting Ants and Trap-Door Spiders, London, 1873, pp. 16-60.
Agricultural Ants.--The art of ama.s.sing stores is still more highly perfected by an Ant which inhabits North America. It is called the Pogonomyrmex barbatus, or, on account of its customs, the Agricultural Ant. It carries out a certain number of preparatory acts, and pushes foresight further than any other animal, since it looks after its property while still growing. It is grain which these insects collect, but only a single species of graminaceous grain. This choice leads them to spend great trouble on their preferred plant. They act in such a way that in the case of men we should say, purely and simply, that they were cultivating. The art of treating the earth with a view of augmenting the products which it yields is certainly of all the manifestations of human activity that which we should least expect to find among animals. It is, however, impossible otherwise to describe the conduct of Agricultural Ants. The field which they prepare is found in front of their ant-hill; it is a terrace in extent about a square metre or more; there they will allow no other plant to grow but that from which they propose to gather fruit. This latter (Aristida stricta) is rather like a grain of oats, and in taste resembles rice; in America it is called ant rice. This culture represents for these insects a much more important property than a wheat field for man. It is, in relation to their size, a forest planted with great trees, in comparison with which baobabs and sequoias are dwarfs. It is not known if the Pogonomyrmex sow their rice; Lincec.u.m a.s.serted that the ants actually sow the seeds, that he had seen the process going on year after year; "there can be no doubt," he concludes, "of the fact that this particular species of gra.s.s is intentionally planted, and in farmer-like manner carefully divested of all other gra.s.ses and weeds during the time of its growth."[58] McCook is not able to accept this unqualified conclusion. "I do not believe that the ants deliberately sow a crop, as Lincec.u.m a.s.serts, but that they have, for some reason, found it to their advantage to permit the Aristida to growupon their disks, while they clear off all other herbage; that the crop is seeded yearly in a natural way by droppings from the plant, or by seeds cast out by the ants, or dropped by them; that the probable reason for protecting the Aristida is the greater convenience of harvesting the seed; but, finally, that there is nothing unreasonable, nor beyond the probable capacity of the emmet intellect, in the supposition that the crop is actually sown. Simply, it is the Scotch verdict--Not proven."[59] However it may be, they certainly allow no other plant to grow in the neighbourhood of their grain, to withdraw the nourishment which they wish to reserve entirely for it. Properly speaking, they weed their field, cutting off with their jaws all the troublesome plants which appear above the soil. They pursue this labour very diligently, and no strange shoot escapes their investigations.
Thus cared for, their culture flourishes, and at the epoch of maturity the grains are collected one by one and carried within. Like all harvesters, these Hymenoptera are at the mercy of a shower that may fall during the harvest. They are well aware that in this case their provisions would be damaged, and that they would run the risk of germination or decay in the barns. Therefore, on the first sunny day all the ants, as observed by Lincec.u.m and Buckley, may be seen carrying their grains outside, only bringing them back when they have been thoroughly dried, and always leaving behind those that have sprouted.[60]
[58] Lincec.u.m"s most important published paper on the habits of the Myrmica molefaciens appeared in the Proc. Acad. Nat. Sci. Philadelphia, vol. xviii., 1866, p. 323-331. See also Darwin, Proceedings of the Linnaean Soc., 1861.
[59] H. C. McCook, Natural History of the Agricultural Ants of Texas, Philadelphia, 1879, pp. 33-39.
[60] McCook, Agricultural Ants of Texas, pp. 105-107.
Gardening Ants.--The Leaf-cutting Ants (Oecodoma) of tropical America are often alluded to by travellers on account of their ravages on vegetation; and they are capable of destroying whole plantations of orange, mango, and lemon trees.
They climb the tree, station themselves on the edge of a leaf and make a circular incision with their scissor-like jaws; the piece of leaf, about the size of a sixpence, held vertically between the jaws, is then borne off to the formicarium. This consists of low wide mounds, in the neighbourhood of which no vegetation is allowed, probably in order that the ventilation of the underground galleries may not be interfered with.For a long time there was considerable doubt as to the use to which the leaf-cutting ants put the leaves; some naturalists supposed they are used directly as food, others that the ants roof their underground dwellings with them. The question was set at rest by Fritz Muller, who observed these ants in Brazil,[61]
and independently by Belt, who studied them in Nicaragua, and has written an interesting account of their proceedings.[62] The real use of the leaves is as manure on which to grow a minute species of fungus; these ants are, in reality, mushroom growers and eaters. Belt several times exposed the underground chambers to observation and found that they were always about three parts filled with "a speckled, brown, flocculent, spongy-looking ma.s.s of a light and loosely-connected substance." Scattered throughout these ma.s.ses were the pupae and larvae, together with the smallest division of workers who do not engage in leaf-carrying, but whose duties appear to be to cut up the leaves into small fragments and to care for the young. On examination the ma.s.ses proved to be composed of "minutely sub-divided pieces of leaves, withered to a brown colour, and overgrown and lightly connected together by a minute white fungus that ramified in every direction throughout it." That they do not eat the leaves themselves was shown by the fact that near the tenanted chambers were found deserted ones filled with the refuse of leaves that had been exhausted as manure, and which served as food for the larvae of various beetles. There are numerous holes leading up from the underground chambers, and these are opened out or closed up, apparently in order to regulate the temperature below.
Great care is also taken that the nest should be neither too dry nor too damp; if a sudden shower comes on the leaves are left near the entrance, and carried down when nearly dry; during very hot weather, on the other hand, when the leaves would be parched in a very short time, the ants only work in the cool of the day and during the night. Occasionally, inexperienced ants carry in gra.s.s and unsuitable leaves; these are invariably brought out again and thrown away.[63]
[61] Nature, 11th June 1874. And see Appendix.
[62] Naturalist in Nicaragua, 2nd edition, 1888, pp. 71-84.
[63] For a brief discussion of the relation of ants to plants generally, see Lubbock"s Ants, Bees, and Wasps, 1882, chap. iii.
Domestic animals of Ants.--Following through different species the perfection reached in the art of laying up provisions for the future, we have gradually arrived at methods resembling those of Man. But a foresight still greater and nearer tohis is manifested by those ants who breed and keep near them animals of different species, not for the sake of their flesh, but for certain secretions, just as man utilises the milk of the cow or the goat. Ants have true domestic animals belonging to a variety of species, but the most widely spread are the Claviger and the Aphides or plant-lice. To keep these insects at their disposal, Hymenoptera act in various ways: some, who are a little experienced, are content to take advantage of a free aphis which chance may put in their way; others shut up their cattle in stables situated in the midst of the ant-hill, or else pen them in the country at a spot where they can best find their food. These facts have long since been carefully studied and leave no room for doubt.
The Claviger testaceus is a small beetle, often met in the dwellings of ants.
Nature has not been very generous on its behalf. It is blind, and its eyes are indeed altogether atrophied. The elytra are soldered at the median edge, so that it cannot spread its wings to fly. It is an animal predestined to the yoke; and for the rest its masters treat it with extreme kindness. The yellow ants, according to Muller,[64] have reduced this outcast beetle to domesticity, and it is almost a piece of good fortune for him to have lost his freedom and to have gained in exchange a shelter and a well-furnished trough. These insects are in fact cared for by their masters, who feed them by disgorging into their mouths the sweet liquids they have gathered here and there. If a nest is disturbed the ants hasten to carry their eggs and larvae out of danger; they display the same solicitude with regard to the Claviger, and carefully bear them to the depth of their galleries. It must not be believed that the practical insect takes so much care in order to repair the injustice of nature towards the beetle; the part of a devoted sick nurse would not suit him; he cares for the Claviger because it is his property, a capital which brings in interest in the shape of excellent sweet little drops which are good to suck.[65]
[64] Ph. W. J. Muller, "Beitrage zur Naturgeschichte der Gattung Claviger,"
Germer u. Zincken"s Magaz. d. Entomol., iii., 1881, pp. 69-112.
[65] There is little doubt, however, that some species of Aphides and allied Coccidae would be liable to extermination if not protected by their ant masters.
See, for instance, Forel, Bull. Soc. Vaud., 1876. Mr. c.o.c.kerell in Jamaica has noted an interesting Coccid, Icerya rosae, which is protected by ants; "at the present moment some of these Iceryae are enjoying life, which would certainly have perished at my hands but for the inconvenience presented by the numbers of stinging ants."--Nature, 27th April 1893. Mr. Romanes (Nature, 18th May 1893)quotes as follows from a letter addressed to him by the Rev. W. G.
Proudfoot:--"On looking up I noticed that hundreds of large black ants were going up and down the tree, and then I saw the aphides.... But what struck me most was that the aphides showered down their excretions independently of the ants"
solicitations, while at other times I noticed that an ant would approach an aphis without getting anything, and would then go to another. I was struck with this, because I remembered Mr. Darwin"s inability to make the aphides yield their secretion after many experiments. A large number of hornets were flying about the tree, but seemed afraid of the ants; for when they attempted to alight, an ant would at once rush to the spot, and the hornet would get out of its way."
A yellow ant, who wishes to enjoy the result of the cares given to his pensioner, approaches it and gently caresses it with his antennae; the other shows signs of pleasure at this visit, and soon a pearly drop appears on the tuft of hairs at the edge of its elytra, and this the ant hastens to lick. The beetle is thus exploited and tickled by all the members of the community to which he belongs who meet him on their road. But when it has been milked two or three times it ceases to secrete.
A solicitous ant arriving at this moment finds its efforts in vain, but still behaves like a good shepherd; it shows no impatience or anger towards its exhausted beast, knowing well that it is only necessary to come back a little later or to go to another member of the herd. Nor are his cares lessened by finding the source dried up. He foresees that it will still be good after repose, and if it is hungry he disgorges food for it.
Degrees of civilisation in the same species of Ants.--These facts are sufficiently marvellous in themselves, but are more surprising when we recollect that they cannot be regarded as an innate and unreflecting instinct with which all the individuals of the same species are endowed. The art of domesticating the Claviger is a stage of civilisation reached by some tribes and not by others.
Lespes[66] has placed this out of doubt in the following manner. He had specimens of Lasius niger who exploited a flock of Coleoptera. Having met ants of the same species who possessed no flocks, he brought them some. At the sight of the little insects they threw themselves on them, killed them, and devoured them. If we compare these facts with those which pa.s.s in human societies, it will seem to us that these latter Hymenoptera behave like a horde of hunters in the presence of a flock of sheep, while the first have already arrived at the sheep-herding stage.[66] "Recherches sur quelques Coleopteres aveugles," Ann. Sc. Nat., v. Serie, t.
ix., 1868, p. 71.
Aphis-pens and paddocks.--Ants can also keep Aphides in their homes. In this case, fearing that the adult beasts may not be able to adopt a change of surroundings and food, they bring the eggs to their nests and care for them at the same time as their own children. In time they come out and const.i.tute a flock easy to tame. Other ants, still more intelligent, have discovered a method of holding the Aphides captive, while allowing them to enjoy their accustomed life, and to feed at will on the foods they prefer on their own favourite spots. It is sufficient for this purpose to establish barriers around a group of cattle who have themselves fixed the place of their sojourn. The Lasius niger, a skilful architect, constructs vaulted pa.s.sages from his dwelling into the country. These covered roads, built with earth moistened with saliva, have various ends; some have been made in order to reach remote work sheltered from the sun, or to give concealment from enemies. Many lead to the pens of the Aphides; they reach from the anthill as far as the foot of a plant where these insects are abundant. In order to have their milkers at their disposal, without removing them from pasture, the ants make tunnels along the stalk, and enclose within it all the Aphides they meet. They thus prevent any desire for a distant ramble. But in order that the flock may not be too closely confined, the Lasius niger enlarge the galleries in places, and make a sort of chamber or stable in which the beasts may disport themselves at ease. These halls, which are proportionately very vast, are supported against the branches and leaves of the plant which bears up the walls and the vaults. The captives find themselves then with all the advantages of material life, and may be milked with every facility.[67]
[67] P. Huber, Recherches sur les Moeurs des Fourmis indigenes, pp. 176-200.
An allied species of ant, the Lasius brunneus, lives almost entirely on the sweet secretion of large Aphides in the bark of oaks and walnut trees. The ants construct around these insects cabins made of fragments of wood, and wall them in completely so as to keep them at their own disposal.