Habit and instinct

Preface

I wish that dedications were still in vogue, so that these pages could be inscribed to all those many friends whose unfailing kindness and courtesy made my visit to the United States so pleasant, when the substance of this volume was delivered as a Lowell Course at Boston, and as lectures in New York, Chicago, and other university centres, during the early part of this year.

The reader will doubtless be glad to learn that further observations — and they are much needed — on habit and instinct will probably form part of Prof. Whitman’s work at an experimental station in connection with the Biological Department of Chicago University. Similar observations might also be prosecuted with advantage in some of our own zoological gardens, as was the earnest wish of George Bomanes, to whose influence and encouragement I am, like many others, so deeply indebted.

A few passages from the Fortnightly Review, Nature, Natural Science, the Monist, and the Humanitarian, may perhaps be recognized. Much of the chapter on Modification has appeared by request in Science,

My best thanks are due to Mr. F. Howard Collins for many valuable suggestions.

C. Ll. M.

Bristol, October, 1896.

Contents

CHAPTER PAGE

I. Preliminary Definitions and Illustrations ... ... 1

II. Some Habits and Instincts of Young Birds ... 29

Chapter II. Some Habits And Instincts Of Young Birds

Much stress has been laid, in tbe foregoing introductory chapter, on tbe distinction between tbe definiteness which is congenital and tbe definiteness which is individually acquired. There would seem to be certain activities tbe definite performance of which is antecedent to individual experience, and these were termed instinctive. There are others which reach definiteness only through a process of learning, through the exercise of intelligence, or through imitation, their definite performance becoming more or less automatic and stereotyped by individual repetition, and these were termed acquired. So far as our present inquiry is concerned, it is on the definiteness that we must fix our attention. And it is a matter for careful and unprejudiced observation to decide whether the definiteness of behaviour, under given circumstances, is congenital or acquired. This question of fact may, for the present, be kept quite distinct from the question of origin. When some of the facts have been given, it will he time to inquire whether the congenital definiteness is due, on the one hand, to the natural selection of slight congenital variations, or, on the other hand, to the inheritance of the adaptive modifications which result from individual acquisition. But the first thing is to collect facts observed with all possible accuracy.

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Nor need we trouble ourselves much at present — not otherwise, that is to say, than incidentally — with the subjective interpretation of the facts. We need not now stay to inquire whether, on the one hand, the performance of a truly instinctive activity — one the definiteness of which is congenital — is a merely organic response (be it accompanied by consciousness or not) ; or whether, on the other hand, there are innate ideas or inherited memories by virtue of which consciousness guides or directs the activity into a definite channel. This question is closely connected with that of origin, inherited memory and inherited acquisition being often associated in one interpretation of the facts — that adopted by those who may be termed transmissionists. This again is a matter the discussion of which may be profitably deferred.

We have to concentrate our attention, then, on the facts established by careful and critical observation, and it will be convenient for many reasons to limit our field at first to the readily observable habits and instincts of young birds. Since they are easily hatched in an incubator so that all maternal influence is avoided ; and since many of them are active soon after birth ; since, too, certain species can be reared without serious difficulty, and subjected to conditions which are pretty well under control ; — on all these grounds they afford satisfactory material for the investigation with which we are now concerned.

Studies of the domestic chick have been made by several observers, notably by Douglas Spalding,* by Professor Preyer,f by Professor Eimer,J and more recently by Dr. Wesley Mills. § Spalding’s observations have been widely

* Macmillan’s Magazine, February, 1873, yol. xxvii., “ Instinct.”

t “ The Mind of the Child,” part i., “The Senses and the Will,” 2nd ed., 1884, Eng. trans., by H. W. Brown.

% “ Organic Evolution,” pp. 245-254, Eng. trans., by J. T. Cunningham, 1890.

§ Transactions B. S. Canada, sect, iv., 1895, p. 249.

quoted, but in some cases their accuracy has not been confirmed by later observers.

The eggs from which the subjects of my own investigation were hatched were either artificially incubated from the first, or were transferred from the hen to the incubator a few days before they were timed to emerge, so that in no case was the behaviour of the young influenced by older birds. They were kept under observation in a small pen or enclosure surrounded by wire netting, or in a room set aside for that purpose, and were occasionally allowed the run of a little garden plot.

Previous to hatching, the little fellows may often be heard chirping within the egg. Young moorhens do so in some cases for as much as forty-eight hours, and ducklings as much as twenty-four hours before they finally emerge, and this in the case of strong and healthy birds. The beak must then have pierced the air-chamber within the egg, and direct air-breathing must have taken the place of embryonic respiration. The eggshell, when they thus begin to chirp within it, is generally, but not always, broken or chipped at one point of its surface. This chirping is a truly congenital activity, and has not to be learnt. One young moorhen, lying silent in the chipped shell, responded by chirping to my low whistle. So that even then they can hear, or at any rate are influenced by an auditory stimulus. Mr. Hudson, referring to “ several species in three widely separated orders,” tells us* that, according to his observations, “when the little prisoner is hammering at its shell, and uttering its feeble peep, as if begging to be let out, if the warning note is uttered, even at a considerable distance, the strokes and complaining instantly cease, and the chick will then remain quiescent in the shell for a * “Naturalist in La Plata,” 1892, p. 90.

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long time, or until the parent, by a changed note, conveys to it an intimation that the danger is over.” Here we have a remarkable connate response to definite stimulus.

In some cases the shell is finally rent by the struggles of the little bird, in whom air-breathing probably provokes increased activity. But some birds, ducks for example, chip the egg along a circle near the broad end. When they emerge, the down is wet and draggled in appearance, and the little new-born things are comparatively helpless for some hours, having, as a rule, little power to hold up their heads, and none to stand firmly. I noticed that newly hatched plovers lay in the drawer with bill on the ground and outstretched neck in a well-known protective attitude. Like the eggs, they assimilate well in colour with their natural surroundings. Some young moorhens, hatched out in a drawer lined with cotton-wool, had taken a good deal into their beaks during the first five or six hours — so much, indeed, that in one case it was in some danger of choking.

There would seem to be some instinctive shrinking from one’s hand when the birds are for the first time taken from the drawer after hatching, and this seems to be the more marked the longer they have been left to recover from the shock of birth. There was, however, little sign of shrinking in plovers or lapwings. Chicks and ducklings lie quiet longer than partridges and pheasants, which soon begin to move about. Any instinctive fear which they may show soon passes by, and after a very little experience they come to the hand instead of shrinking from it. Still, we may probably regard the shrinking as congenital, but more marked at a slightly deferred period of life. And perhaps there may be in this a special adaptation. The hen, for example, is a somewhat fussy being, and, in the absence of any instinctive knowledge of her as their natural protector (for it is probable that there is no such instinctive knowledge), very strong connate shrinking on the part of the chicks would lead them rather to avoid her than to submit to her ministrations. Hence it comes that the young birds accommodate themselves to a foster-parent even so strange as a human being, if he take them in hand early enough. There is also from the first an instinctive tendency to nestle into any warm, soft place. When there are several little birds in the incubator drawer, they cuddle together and burrow under each other in a very comical manner. And when one has older and younger birds, the little ones get in under and between the legs of their seniors in a way that appears to be somewhat embarrassing to the latter. This was, for example, especially notable with two recently hatched moorhens, which persistently tried to cuddle down under the lanky legs of two older birds of the same species. So, too, in a mixed brood of several species I had under observation, a little guinea-fowl and a still younger pheasant tried to cuddle down under a wild duck and a tame duck, a day or two older than themselves, with a touching confidence that was not at all appreciated by the greedy ducklings, eager only for food. Dr. Mills introduced to his chicks two pigeons (a white pouter, and a black owl), to test whether the chicks would show any instinctive fear. Not at all ; the little birds nestled under them !

This instinctive action is, of course, under nature, in adaptation to the corresponding instinctive behaviour of the mother-bird, who takes them under her wing. But with hand-reared birds the instinctive tendency acquires a new direction, and undergoes modification. Chicks, pheasants, partridges, plovers, moorhens, and other young birds, whether wild by nature or of domesticated breeds, would all run to my hands, after a very short time,

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nestle down between them, and poke out their little heads confidingly between my fingers. Here, then, there is a congenital and instinctive tendency, to nestle in any warm place, modified in accordance with acquired individual experience. It was pretty to see three little partridges, two French and one English, following me about the room wherever I went. And when the instinctive tendency is thus modified, its natural end seems to lapse ; for chicks even a few days old seem to have completely lost any instinctive tendency they may have possessed to run to and cuddle under the hen. As to the existence of any such instinctive response to the sight of the hen, or to her clucking, there is difference of opinion.

Spalding describes * how a chick, which had been blindfolded at birth, was placed, twenty minutes after it had been unhooded, “on rough ground, within sight and call of a hen with a brood of its own age. After standing chirping for about a minute, it started off towards the hen, displaying as keen a perception of the qualities of the outer world as it was ever likely to possess in afterlife. It never required to knock its head against a stone to discover that there was ‘ no road that way.’ It leaped over the smaller obstacles that lay in its path, and ran round the larger, reaching the mother in as nearly straight a line as the nature of the ground would permit. This, let it be remembered, was the first time it had ever walked by sight.”

Other chicks, which had been placed in a bag immediately they were hatched and kept there for a day or two, ran eagerly to the clucking of a hen hidden from their view in a box nine or ten feet distant. This observation was repeated on nine different chicks. But Spalding draws our attention to the fact that this * Loc. cit., p. 289.

instinctive response to a specialized auditory stimulus was completely lost at the end of ten or twelve days.

The results of my own observations may now be briefly described. I took two chicks ten days old to the yard whence I had received the eggs from which they had been hatched, and opened the basket wherein they had been conveyed, about two yards from a hen which was clucking to her brood. Though they were not in a frightened condition, as shown by the fact that they jumped on my hand and ate grain off it, scratching at my palm, they took no notice whatever of the clucking of the hen. I then placed them with another hen in a small fowl-house ; but they took little heed of her, neither running to her nor seeming frightened, or, if at all, but little. Three other chicks were taken when they were thirteen days old to the yard, and were put down outside a fowl-house in which a hen was clucking to her brood. They also took no notice of the sound, but scratched about quite unconcernedly. Subsequently they were placed with the hen, who seemed inclined at first to drive them away, but afterwards looked more kindly on them, though they did not keep close to her like the others. I went over on the following day, and when I bent down and held out my hand, one of my little friends ran to it and nestled down confidingly. So far my observations confirm what Spalding says concerning the loss of the instinctive response, or, at any rate, its absence after the lapse of a few days. But] the following case shows that the instinctive recognition of the hen, if indeed it exist at all, is very soon lost. I took a chick at two and a half days old (that is to say, at about the same age as Spalding’s birds) to its own mother, which had three chicks. These followed her about, and ran at once to her when she clucked and pecked on the ground. The little stranger

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took no notice whatever of the clucking of its, till then unknown, mother, and did not show any tendency either to go to the hen or to follow the three chicks. He pecked about independently and unconcernedly, eating grain, and seizing small stones, but came to my hand when I held it out towards him, and cuddled down in it. When the hen took her three chicks under her wing, the stranger was placed close to her. She clucked and seemed anxious to entice and welcome the little fellow, seizing an oathusk and dropping it before the chick, which, however, took no notice whatever, but walked away and stood in the sun. After about forty minutes he seemed more inclined to go with the other chicks, but still ignored the existence of the hen. Thus I have not found any truly instinctive response to the clucking of a hen ; but, as before noticed, Spalding recorded a different result. And Mr. Hudson’s observations on the effects of warning notes on unhatched birds indicate a truly congenital response in their case. We need more evidence.

We may now turn to the instinct of pecking, and the congenital definiteness of orderly movements which it involves. As the observations of Spalding, Eimer, Preyer, and others have conclusively proved, the pecking at grain and other small objects is a definitely congenital activity, and one, be it noted, which involves remarkable nicety and complexity of co-ordination. The aim is, however, seldom quite correct at first, though very nearly so, the object, if not struck, being only just missed, though the accuracy was somewhat exaggerated by Spalding. In some cases the tendency seems to strike a little short of the object. Moving the grain or egg-fragments with a pin, or dropping some before the chick, causes the edible material more readily to catch the eye. Most noteworthy is the fact that the young birds only strike at objects which are well within striking distance ; they have not to learn this distance by experience. To peck at an object of a certain size, just within easy reach, is a definitely congenital response, and not the result of acquired skill. In nearly all cases, as one might expect, the simpler process of striking is more accurate than the more complicated process of striking and seizing ; and this, again, than the yet more elaborate process of striking, seizing, and swallowing. Nevertheless, this yet more complicated activity, or train of activities, is performed so soon, and with so few trials — often at the third or fourth attempt — that one must regard the whole as essentially congenital in its definiteness, and look upon the few preparatory efforts as merely the steadying of the inherited organic apparatus to its work.

Of the birds which I have had under observation, partridges, both English and French, pecked earlier and with better aim than any others, but soon desisted if what they pecked at was not satisfactory. Plovers (my observations were on the common peewit or lapwing) were slow to peck, and their co-ordination seemed relatively poor. Chicks and guinea-fowl were about on a par ; pheasants somewhat less keen. Ducklings — those of wild ducks and tame ducks being, so far as I could note, equal in this respect — peck early and with fair aim, but they do not seize and swallow so readily. They mumble what they seize, and often shake it out of the bill unswallowed. Moorhens show a somewhat different instinctive tendency. From the first they crouch down with the head and neck held back, and the skinny little wings working to and fro ; in this attitude they open their beaks more like the callow young of jackdaws or other nursling birds than the young of fowls or pheasants. They soon strike, however, with fair accuracy of aim, at objects held above them ;

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but it is some time before they will pick up food from the ground. I tried with two moorhens the experiment of feeding them as little as possible from the hand, so as to induce them to eat independently, but with fatal results. Mr. Crisp, who has had good opportunities of watching these birds under natural conditions in the moat beneath the walls of Playford Hall, in Suffolk, informs me that the parent birds always feed the young from their beaks during the first few days of life. The instinctive attitude quite bears out the accuracy of this observation.

When they are a little older, and have had some practice, their keenness of eye, both at long and short distances, and their accuracy of aim are alike wonderful. One, about ten days old, after nestling awhile in my hand, singled out and seized in his bill several not very conspicuous hairs on the first joint of my fore-finger. There was also a speck of white on my hand, which caught his eye, and at which he pecked with complete accuracy of aim again and again. A few days after, one pecked at a minute black speck on my hand, though it was but a quarter of an inch from the tip of his bill. Shortly afterwards, in the garden, he spied a small ant moving on the wall about four feet distant, ran, and seized it. The field of vision is very soon completely ordered for practical use.

I took a young pheasant, which had been hatched some time in the night, from the incubator drawer at nine o’clock in the morning. He was very unsteady on his legs, so I held him in my hand, and tried to induce him to peck at a piece of egg-yolk held in a pair of forceps. He did not do so ; but he followed, with his head, every movement of the object in a narrow circle about two inches in front of his beak. Simple as the action seems, it shows a striking example of congenital co-ordinated movements accurately related to movements in the visual field, the whole performed without any possibility of learning or practice, and less than half an hour after the bird had first seen the light of day. On the other hand, two nestling jays, brought to me when they were about ten days old, were quite unable to follow in this way food moved slowly over their heads. They merely gaped for it to be put into their mouths. When they began, after a day or two, to follow an object with the head and eye, the movements were at first jerky. In a week, when I swept the food through a circle a foot in diameter in front of their cage, it was followed smoothly and evenly. It was curious to see the two jays following it thus, their heads moving in unison through a small circle corresponding to my wider sweep. Here a certain amount of individual learning and practice, absent in the case of the pheasant, was required.

Chicks, pheasants, and other birds which are active shortly after birth may be induced to peck by tapping on the ground with the finger-nail, a pencil, or penholder, thus simulating the pecking action of the hen, and may thus be induced to seize objects which they wrould otherwise leave untouched. Mr. S. E. Peal* states that the Assamese, when they find newly hatched pheasant chicks in the jungle, teach the little ones to peck and pick up food by sharply tapping among the crushed rice and egg on which they feed them, and say that without this many of them would die. Professor Claypole informs me, on the authority of a friend who had practical experience, that young ostriches hatched in the incubator will not pick up food for themselves unless the ground be tapped so as to suggest the action of pecking. But on young moorhens this has no effect, and I could not find much response, if any, in plovers.

* Nature , April 9, 1895.

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The facts above noted possibly gave origin to the supposition to which Darwin gave his support/ that pecking is, in young chicks, primarily suggested through the sound of pecking. But both Spalding and Professor Preyer showed t that sound does not necessarily play any part in initiating the pecking activity. And my own observations fully confirm theirs. It is apparently the sight of the artificial pecking, and the movement thus caused among the grains of food, rather than any sound made, that has suggestive value.

With regard to the objects at which domestic chicks peck, in the absence of any parental guidance, one may say that they strike at first with perfect impartiality at anything of suitable size ; grain, small stones, breadcrumbs, chopped-up wax matches, currants, hits of paper, buttons, beads, cigarette-ash and ends, their own toes and those of their companions, maggots, bits of thread, specks on the floor, their neighbours’ eyes — anything and everything, not too large, that can or cannot be seized is pecked at, and, if possible, tested in the bill. Similarly with young pheasants, guinea-fowl, and moorhens. I watched the latter for an hour the second or third time they were put out in my little garden. They pecked at everything of suitable size they could lay bill on. There does not seem to be any congenital discrimination between nutritious and innutritious objects, or between those which are nice and those which are nasty. This is a matter of individual acquisition. They soon learn, however, what is good for eating, and what is unpleasant, and rapidly associate the appearance with the taste. A young chick two days old, for example, had learnt to pick out pieces of yolk from

* “ Expression of the Emotions,” 1st edit., 1872, p. 47. On the authority of Mowbray.

others of white of egg. I cut little bits of orange-peel of about the same size as the pieces of yolk, and one of these was soon seized, but at once relinquished, the chick shaking his head. Seizing another, he held it for a moment in the bill, hut then dropped it and scratched at the base of his beak. That was enough; he could not again be induced to seize a piece of orange-peel. The obnoxious material was now removed, and pieces of yolk of egg substituted, but they were left untouched, being probably taken for orange-peel. Subsequently, he looked at the yolk with hesitation, but presently pecked doubtfully, not seizing, but merely touching. Then he pecked again, seized, and swallowed.

To some other chicks I threw cinnabar larvae, distasteful caterpillars conspicuous by alternate rings of black and golden-yellow. They were seized at once, but dropped uninjured ; the chicks wiped their bills — a sign of distaste — and seldom touched the caterpillars a second time. The cinnabar larvae were then removed, and thrown in again towards the close of the day. Some of the chicks tried them once, but they were soon left. The next day the young birds were given brown loopers and green cabbagemoth caterpillars. These were approached with some suspicion, but presently one chick ran off with a looper, and was followed by others, one of which stole and ate it. In a few minutes all the caterpillars were cleared off. Later in the day they were given some more of these edible caterpillars, which were eaten freely; and then some cinnabar larvae. One chick ran, but checked himself, and, without touching the caterpillar, wiped his bill — a memory of the nasty taste being apparently suggested by association at sight of the yellow-and-black caterpillar. Another seized one, and dropped it at once. A third subsequently approached a cinnabar as it crawled along, gave the danger

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note, and ran off. Then I threw in more edible caterpillars, which again were eaten freely. The chicks had thus learnt to discriminate by sight between the nice and the nasty caterpillars. Similarly, moorhen chicks rapidly discriminated between small edible beetles and soldier beetles. Such discrimination is, however, not congenital, but acquired. The young birds do not for some little time avoid pecking at their own fresh excrement, though this is obviously distasteful.

The cinnabar caterpillars are, as I have said, conspicuously marked with alternate yellow and black rings. It would seem that the end of this conspicuousness is to render association in the individual experience of young birds more rapid and more certain ; there does not appear to be any congenital and instinctive avoidance of such caterpillars with warning colours. Young moorhens found the conspicuously marked burnet moth distasteful, the obnoxious part being the wings, for the body from which the wings were removed was eaten with apparent relish, while the severed wings were rejected with evident signs of distaste. I was desirous of ascertaining whether the different appearance of brandlings ( Lumbricus fcetidus) and other small worms was sufficient to enable the moorhens to distinguish them, but this was apparently not the case. The experiment showed, however, the marked influence of the first experience. For the moorhen which was given a brandling first was long before he would touch any worm, while that which was given a brandling after several less highly flavoured worms, though he was rendered a little suspicious for a time, picked up each cautiously and rejected or swallowed it according to the taste. A few days later, however, both moorhens would eat brandlings when they were hungry.

My observations with regard to the effects of giving to young birds distasteful insects were made solely with a view to ascertain whether there was any instinctive avoidance on the part of the birds. Of this I have not found a single instance. Cinnabar caterpillars (Euclielia, jacobice) were tried and avoided after a few trials by all the birds on which I have made observations, though one hungry jay ate five in succession, never again eating another, though he had frequent opportunities. The brown pupae of this moth were eaten by jays with apparent relish. All avoided large woolly-bear caterpillars ( Arctia, caja ) ; but whereas jays, ducks, and moorhens ate small caterpillars of the wood tiger moth ( Nemeophila plantaginis) and the cream-spot tiger moth ( Chelonia villicd ), the chicks, pheasants, and guinea-fowl to which they were given found them distasteful. Jays ate freely the pupae of the currant moth (. Abraxas grossulariata), but on the following day took them less readily, and with some wiping of the bill. One of the jays also ate the large larva of the buff-tip moth (Phalera bucepliala) , which the other jay rejected, as did ducklings and chicks. After wiping it to and fro across his perch, he tore it, eating the inside with apparent relish, and leaving the skin for a time. This he subsequently swallowed. Two days later he ate another in the same manner. Moorhens, as already mentioned, found the wings of the burnet moth (Zygsena filipendulce) distasteful. Soldier beetles and ladybirds were invariably tested, and avoided as the result of experience. The net result of these observations is that, in the absence of parental guidance, the young birds have to learn for themselves what is good to eat and what is distasteful, and have no instinctive aversions.*

I am not, of course, prepared to say that in no case

* My thanks are due to Mr. G. C. Griffiths for kindly sending me larvae and pupae.