Animal Behaviour

by C. Lloyd Morgan

That in some cases there is something very like a training or education of the ant when it emerges from the pupa condition is rendered probable by the observations of M. Forel. As Romanes says,[51] “The young ant does not appear to come into the world with a full instinctive knowledge of all its duties as a member of a social community. It is led about the nest and ‘trained to a knowledge of domestic duties, especially in the case of larvæ.’ Later on, the young ants are taught to distinguish between friends and foes.”

We have only to weigh the evidence brought forward by such observers as Fabre and Dr. Peckham to see that among the solitary wasps and mason bees the behaviour, though founded on instinct, is in large degree modified by intelligence. The care with which a site for the tunnelled nest in the ground is selected, betokens something more than instinct. The following is a slightly condensed statement of Dr. and Mrs. Peckham’s observations on one of the solitary wasps (Aporus fasciatus).[52] “We were working one day in the melon-field when we saw one of these little wasps going backwards and dragging a spider. She twice left it on the ground while she circled about for a moment, but soon carried it up on to one of the large melon leaves, and left it there while she made a long and careful study of the locality, skimming close to the ground in and out among the vines; at length she went under a leaf close to the ground, and began to dig. After her head was well down in the ground we broke off the leaf that we might see her method of work. She went on for ten minutes without noticing the change, and then, without any circling, flew off to visit her spider. When she tried to return to her hole it was evident that some landmark was missing. Again and again she zig-zagged from the spider to the nesting-place, going by a sort of path among the vines from leaf to leaf, and from blossom to blossom, but when she reached the spot she did not recognize it. At last we laid the leaf back in its place over the opening, when she at once went in and resumed her work, keeping at it steadily for ten minutes longer. At this point she suddenly reversed her operations, and began to fill in the hole that she had made. She then glanced at the spider, selected a new place, and began to dig again. This hole was also filled in; she looked once more at the spider, and started a nest in a new place. This, in turn, was soon abandoned, as was a fourth. The fifth beginning was made under a leaf that lay close to the ground, but after twenty minutes’ work this place also was abandoned and a sixth started. This, however, was the final choice, and after forty-five minutes spent in digging it was completed.”

Fig. 19.—Solitary Wasp using a stone to beat down the earth over its nest (after Peckham).

This description shows an amount of apparent fastidiousness which is quite irreconcilable with the hypothesis that the behaviour is merely instinctive. Not less fastidious are some wasps in the temporary closure of the hole with a stone or pellet of earth, the operation being repeated several times with different covers before the insect seems to be satisfied; while in other cases the hole is hidden by bringing earth in such quantity as to render the place indistinguishable from the rest of the field. But in one case observed by Dr. Peckham, intelligent procedure was carried so far as apparently to involve the use of a tool, the same behaviour having been independently observed in the same genus (Ammophila) by Dr. S. W. Williston of Kansas University. “Just here,” writes Dr. Peckham,[53] “must be told the story of one little wasp whose individuality stands out in our minds more distinctly than that of any of the others. In filling up her nest she put her head down into it and bit away the loose earth from the sides, letting it fall to the bottom of the burrow, and then, after a quantity had accumulated, jammed it down with her head. Earth was then brought from the outside and pressed in, and then more was bitten from the sides. When, at last, the filling was level with the ground, she brought a quantity of fine grains of dirt to the spot, and, picking up a small pebble in her mandibles, used it as a hammer in pounding them down with rapid strokes, thus making this spot as hard and firm as the surrounding surface. Before we could recover from our astonishment at this performance she had dropped her stone and was bringing more earth, and in a moment we saw her pick up the pebble and again pound the earth into place with it. Once more the whole process was repeated, and then the little creature flew away.”

Here we have intelligent behaviour rising to a level to which some would apply the term rational. For the act may be held to afford evidence of the perception of the relation of the means employed to an end to be attained, and some general conception of purpose. In this section, which deals with description of behaviour based on observation, the psychological explanation cannot be discussed. Similar indications of deliberate action may be held to be afforded by the sometimes elaborate “locality studies” which these insects seem to make,—by the “care that is taken by wasps to acquaint themselves with the surroundings of their nests.” A Sphex, for example, which had partially made and then abandoned several nests, left them without any locality study; but when she had completed a nest in a suitable spot she made “a most thorough and systematic study of the surroundings. She flew in and out among the plants, first in narrow circles near the surface of the ground, and then in wider and wider ones as she rose higher in the air, until at last she took a straight line and disappeared in the distance.” Another species (Cerceris deserta) “has the habit of making a number of half circles in front of the nest, and then, after rising a little higher, of flying several times completely round it.” The method of procedure is, it seems, so normal to the species that it is probably founded on an instinctive basis. Dr. and Mrs. Peckham, in commenting on their observations, say:[54] “If the examination of the objects about the nest makes no impression upon the wasp, or if it is not remembered, she ought not to be inconvenienced nor thrown off her track when weeds and stones are removed and the surface of the ground is smoothed over; but this is just what happens.” For convenience of observation they “sometimes gently moved intercepting objects to one side, but even such a slight change threw the wasp out of her bearings, and made it difficult for her to recover her treasure.” Where wasps form a number of nests in a small plot of ground, as in the case of Bembex, each knows and returns to its own hole, as was proved by Dr. Peckham, who marked the insects and their nests with paint.

So, too, with regard to prey. In the course of his observations on Pompilus, Fabre removed the spider which the wasp had deposited on a tuft of vegetation before she made her nest. As she was at work beneath the surface she could not see what went on above ground or where the spider had been redeposited some twenty inches from its former position. On emerging from the nest the wasp went straight to the original spot, searched round it for some time, then made further excursions, and discovered the spider. After slightly altering its position, and placing it on another tuft of vegetation, she returned to her subterranean labours, giving the observer an opportunity of again moving the spider. Five times did Fabre repeat the operation, and every time the wasp returned to the spot where she had last deposited her prey.

The same observer records some interesting experiments with the mason bee, Chalicodoma. The mud nests of the species investigated were affixed to stones on the banks of the Rhone. When a nest was partially constructed, the bee having flown off for more material, Fabre moved the stone to a new position, near at hand and easily visible from the original site. The bee went straight to the place where the nest had been, searched the immediate neighbourhood, flew off, and returned to the same spot to continue the search. If she came across her own nest in its new position she did not recognize it as hers, but left it after examination. But if a stone with the nest of another bee in about the same stage of construction was placed in the position occupied by her own, she adopted it. And when two nests near together, both half built, were transposed, each bee unhesitatingly adopted the nest which occupied the position where its own nest had been. It may well seem strange that, the general locality-memory being so well marked, the recognition of the particular stone and nest should be deficient. This may be due to the fact that the so-called compound eyes are the organs concerned in locality vision, while the ocelli deal with details at very close range, and that the former alone afford the requisite data for recognition; by their instrumentality alone arises the conscious situation which affords guidance in behaviour. And in that situation slight changes which for us make it “still the same but with a difference” render it no longer the same for a being of more limited intelligence—one probably incapable of analyzing the situation and seeing that the sameness preponderates over the difference. Be this as it may, the failure of a bee to recognize its own nest under circumstances so foreign to its experience as removal to a new spot may be paralleled with what I have observed in the case of sticklebacks. A nest had been built in a round glass bell jar which stood near a window. Some aquatic vegetation grew in the tank, and the nest was built on the window side. An experiment was made by turning the large bell jar through a right angle. The male stickleback searched for its nest in the old direction on the window side—that is to say, the same position in reference to the incidence of the light. The search was, of course, fruitless, and a new nest was begun in this position. Presently the old nest was discovered, and was then vigorously destroyed in just the same way as the nest of a rival is pulled to pieces and scattered. Here a new incidence of light and new direction of shadows seemed to have completely transformed the visual situation.

To return to insects, it is probable that the homing faculty is not the result of an inborn mysterious instinct dependent on some sense of direction of which we have no knowledge, but is based upon experience gained during their flight hither and thither—that, in a word, it is intelligent and not instinctive. Experiments of Fabre at first seemed to suggest some magnetic influence to which bees were sensitive; for when a minute magnet was fixed to a bee as it started on its return journey, the insect was at fault; but as a check experiment he affixed a piece of straw instead of a magnet, with similar results. Some of Fabre’s observations and those of Dr. Bethe[55] are difficult to reconcile with the hypothesis that, in the homing, guidance is due to acquired acquaintance with the locality. But, on the other hand, the experiments of Lord Avebury and of Romanes seem to favour this view. Romanes found that when bees were taken inland from their hive near the seaboard, and then liberated, they returned from considerable distances, the whole locality being familiar; but taken to the seashore, where the objects around them were unfamiliar (since the seashore is not the place where flowers and nectar are to be found), the bees, though not far distant from the hive, were nonplussed and lost their way. Dr. and Mrs. Peckham, as the result of their extremely careful observations, seem to have no doubt that the homing of solitary wasps is due to locality-experience; and of the social wasp, Polistes fusca, they say:[56] “We have seen the young workers make repeated locality studies when they first began to venture away from home, but as they occupy the same nest all summer they, of course, grow more and more familiar with their surroundings, until they become so thoroughly acquainted with them that they can find their way without the least difficulty. We have no doubt that with them, as with the solitary wasps, the faculty is not instinctive, but is the direct outcome of individual experience.”