Part 7
A _chaprassi_ was appointed to nurse my two young mynas, with instructions to keep them until they should become somewhat more presentable. At the end of three weeks they were adjudged fit to appear in public, being somewhat smaller and rather lanky editions of their parents, with the patch behind the eye white instead of yellow. Having been taken from the nest they were perfectly tame, showing no fear of man, and readily accepting food from the hand.
Young nestlings display no fear of man, and do not appear to mind being handled by a human being; but as they grow older they learn to fear all strange creatures, hence it is that captive birds taken from the nest are always tamer than those which are caught after they are fledged. It was amusing to see the way in which my young mynas ran towards the _chaprassi_ when he called “Puppy, puppy.” “Puppy” is apparently a term applied by native servants indiscriminately to any kind of pet kept by a _sahib_.
Mynas make excellent pets because they are so alert and vivacious, and, above all, because they have so much character.
A myna is a self-assertive bird, a bird that will stand no nonsense.
I know of few things more amusing than to witness a pair of mynas give a snake a bit of their minds as they waltz along beside it in a most daring manner.
Owing to the self-assertion of the myna he is apt to be quarrelsome.
Street brawls are, I regret to say, by no means uncommon. In these two or three mynas attack one another so fiercely that they get locked together and roll over and over—a swearing, struggling ball of brown, yellow, and white.
The myna, although by no means a songster, is able to emit a great variety of notes, all of which must be familiar to every Anglo-Indian.
A bird which can produce a large number of sounds is almost invariably a good mimic, and the common myna is no exception to this rule. In this respect, however, he does not compare favourably with the grackles or hill-mynas, as they are commonly called. These can imitate any sound, from the crack of a whip and the exhortations of a bullock-cart driver to the throat-clearing operation in which our Indian brethren so frequently indulge.
SWIFTS
Swifts are extraordinary birds; there are no others like unto them; they are the most mysterious of the many mysterious products of natural selection; their athletic feats transcend the descriptive powers of the English language. What adjective is there of suitable application to a bird that speeds through the air without an appreciable effort at the rate of a hundred miles an hour, that traverses a thousand miles every day of its existence?
These wonderful birds are everywhere common, yet much of their life history requires elucidation.
Probably not one man in fifty is able to distinguish between a swallow and a swift. Some think that “swift” and “swallow” are synonymous terms, while others believe that a swift is a kind of black swallow. As a matter of fact, the swift differs more widely from the swallow than the crow does from the canary. There is, it is true, a very strong professional likeness between the swift and the swallow, but this likeness is purely superficial; it is merely the resemblance engendered by similar modes of obtaining a livelihood. Both swallows and swifts feed exclusively on minute insects which they catch upon the wing, hence both have a large gape, light, slender bodies, and long, powerful wings. But speedy though it be, the swallow is not in the same class with the swift as a flyer. When both birds are in the hand nothing is easier than to tell a swift from a swallow or a martin. The latter have the ordinary passerine foot, which consists of three forwardly directed toes and a backwardly directed one. This foot enables a bird to perch, so that one frequently sees swallows seated on telegraph wires. But one never sees a swift on a perch, because all its four toes point forward. It cannot even walk. It spends its life in the air. It eats and drinks on the wing, it does everything, except sleeping and incubating, in the air.
But it is not often that one has a swallow or swift in the hand; it is difficult to get near enough to them to put salt on the tail, so that it is necessary to have some means of distinguishing them when sailing through the air. There is a very marked difference in the manner in which these birds use their wings. This is inimitably described by Mr. E. H. Aitken: “As a swallow darts along, its wings almost close against its sides at every stroke, and it looks like a pair of scissors opening and shutting. Now a swift never closes its wings in this way. It whips the air rapidly with the points of them, but they are always extended and evenly curved from tip to tip like a bow, the slim body of the bird being the arrow.” As a swift speeds through the air it looks something like an anchor, with a short shaft and enormous flukes. If this be borne in mind, it is scarcely possible to mistake a swift for a swallow. Swifts are abundant in Calcutta, but one is not likely to come across a swallow there except when the moon happens to be blue.
The two swifts commonly seen in Calcutta are the Indian swift (_Cypselus affinis_) and the palm swift (_C. batassiensis_).
The latter need not detain us long. It is a small and weak edition of the former. It builds a cup-shaped nest on the under side of the great fan-like leaves of the toddy palm.
The Indian swift is, in size and appearance, much like the swift which visits England every summer, except for the fact that it has a white patch on the lower part of the back. The chin is white, but all the rest of the plumage, with the exception of the above-mentioned patch, is black or smoky brown.
This bird nests in colonies in the verandahs of houses and inside deserted buildings. The nest is a cup-shaped structure, usually built under an eave in the angle which a roof-beam makes with the wall. Thus the swift finds, ready-made, a roof and a couple of walls, and has merely to add the floor and remaining walls, in one of which it leaves a hole by way of entrance to the nursery. Thus the swift reverses the usual order of things, which is to erect a nest on some foundation such as a branch or ledge.
As we have seen, all four toes of the swift are forwardly directed and each is terminated by a sharp hook-like claw. Thus the swift is able to cling with ease to such a vertical surface as that of a wall, and is therefore quite independent of any ledge or perch. The nest is a conglomeration of grass, straw, and feathers, which are made to adhere to one another, and to the building to which the nest is attached, by the cement-like saliva of the bird.
Some species of swift build their homes entirely of their glutinous saliva, and so manufacture “edible birds’ nests.” The Indian swift, however, utilises all manner of material by way of economising its saliva.
Nest building is a slow process. Each tiny piece of material has to be separately stuck on to the structure, and the saliva, which is, of course, liquid when first secreted, takes about five minutes to dry. During the whole of this time the bird remains motionless, holding _in situ_ whatever it is adding to the structure.
I once timed a pair of swifts at work, and found that on an average they took forty-five minutes in bringing each new piece of material. Much of this time was undoubtedly spent in seeking for food, for so active a bird as the swift must have an enormous appetite, and, as it feeds on the minutest of insects, must consume thousands of them in the course of the day, each of which has to be caught separately. But, even allowing for this, the rate at which the material is added is very slow. Some naturalists declare that the swift is unable to pick anything off the ground. If this be so, the labour of obtaining material must be great, for the creature must fly about until it espies a feather or piece of straw floating in the air.
I am not yet in a position to say whether it is really impossible for the bird to pick anything from off the ground. I have never seen it do so, and it is a fact that the birds will, when building, eagerly seize anything floating in the air. On the other hand, the helplessness of the swift when placed upon the ground has been much exaggerated. It is said that the bird, if put upon a flat surface, is unable to rise and will remain there until it dies. Quite recently some Indian swifts were brought to me and I placed one of them on my desk. In less than twenty seconds the bird was flying about in the room. Then, again, the grasping powers of its hook-like claws have been somewhat magnified. The bird in question made several unsuccessful attempts to cling on to the whitewashed wall, and eventually fell to the floor, where it was seized and then liberated in the open. It flew off none the worse for its adventure. Nevertheless, its claws are very sharp; the bird in question stuck them quite unpleasantly into me when I held it. A swift can certainly cling to any vertical surface that is the least rough.
Unlike most birds, swifts use their nests as houses and sleep in them at night. One frequently hears issuing from the rafters in the dead of night the piercing scream so characteristic of swifts. This disposes of the silly story, so prevalent, that at evening time the swifts mount into the higher layers of the atmosphere and there sleep on the wing.
In conclusion, I must mention the characteristic flight of swifts just before sundown. The birds close the day in what has been called “a jubilant rout”; as if they had not already taken sufficient exercise, they fly at a breakneck pace round about the building in which their nests are placed, dodging in and out of the pillars of the verandah, and fill the air with their shivering screams. This seems to be a characteristic of swifts wherever they are found.
BIRDS AS AUTOMATA
The sudden change that comes over the nature of most birds at the nesting season is, perhaps, the most wonderful phenomenon in nature. Active, restless birds, which normally spend the whole day on the wing, are content to sit motionless in a cramped position upon the nest for hours together. Birds of prey, whose nature it is to devour every helpless creature that comes within their grasp, behave most tenderly towards their young, actually disgorging swallowed food in order to provide them with a meal. Timid birds become bold. Those which under ordinary circumstances will not permit a human being to approach near them, will sometimes, while brooding, actually allow themselves to be lifted off the nest.
At the breeding season intelligence, which counsels self-preservation, gives way before the parental instinct, which causes birds to expose themselves to danger, and, in some cases, even to sacrifice their lives for the sake of their offspring.
From the construction of the nest until the time when the young ones are fledged the actions of the parent birds are, at any rate in the neighbourhood of the nest, those of automata, rather than of creatures endowed with intelligence.
On this hypothesis alone are many of the actions of nesting birds comprehensible.
That the construction of the nest is in the main an instinctive habit and not the result of intelligence is proved by the fact that a bird which has been hatched out in an incubator will, at the appointed season, build a nest. If birds were not guided by instinct they would never take the trouble to do such a quixotic thing. What benefit can they derive from laboriously collecting a number of twigs and weaving them into a nest?
It is, of course, natural selection that has originated this instinct; for those species in which the parental instinct is not developed, or in which there is not some substitute for it, must inevitably perish. When once this instinct has taken root natural selection will tend to perpetuate it, since those species which take the best care of their young are those which are likely to survive in the struggle for existence.
Many instances can be adduced to show how automatic are the actions of birds at the nesting season.
It sometimes happens that a bird lays an egg and then proceeds to build a nest on top of it.
Again, some birds do not know their own eggs. A whole clutch of different ones may be substituted for those upon which the bird is sitting and the bird will not discover the change.
The well-known bird-photographer, Mr. R. Kearton, was desirous of obtaining a good photograph of a sitting thrush, and as he was afraid that her eggs would be hatched before a fine, sunny day presented itself, had some wooden dummies made. These he painted and varnished to look like those of the thrush, and put them in the nest, wondering whether the bird would be deceived. He need not have wondered; she would probably have sat upon the shams even had they not been coloured.
Upon another occasion Mr. Kearton replaced some starling nestlings by his wooden eggs, and waited to see what would happen. “In a few minutes,” he writes, “back came the starling with a rush. She gazed in wonder at the contents of the nest for a few seconds, but, quickly making up her mind to accept the strangely altered condition of things, she sat down on the bits of painted wood without a trace of discontent in either look or action. Putting her off again, I reversed the order of things and waited. Upon returning, the starling stared in amazement at the change that had come over the scene during her absence; but her curiosity soon vanished, and she commenced to brood her chicks in the most matter-of-fact way.” Then Mr. Kearton took out the chicks and put his fist into the nest, so that the back of his hand was uppermost. The starling actually brooded his knuckles. We must, of course, remember that a starling’s nest is in a hole, where there is but little light. But, provided the starling could not see him, I believe that she would have brooded his knuckles in broad daylight.
Crows, the most intelligent of birds, will sit upon and try to hatch golf balls and ping-pong balls. One famous kite in Calcutta sat long and patiently in a vain attempt to make a pill-box yield a chick, while another member of this species subjected a hare’s skull to similar treatment. Upon one occasion I took a robin’s egg that was quite cold and placed it among the warm ones in a blackbird’s nest. The hen came and brooded the egg along with her own without appearing to notice the addition, although it was much smaller than her eggs and of a totally different colour.
In the same way, if a set of nestlings of another species be substituted for those already in the nest, the parent birds will usually feed the new family without noticing the change. Instinct teaches a bird to brood all inanimate objects it sees in the nest and to feed all living things, whether they be its own offspring or not, and many birds blindly obey this instinct. It is, of course, to the advantage of the species that this should be so. For it is only on very rare occasions that foreign objects get into a nest, and nature cannot provide for such remote contingencies.
Similarly, instinct will not allow a bird to pay any attention to objects outside the nest, even though these objects be the bird’s own offspring.
As everybody knows, the common cuckoo nestling ejects its foster-brethren from the nest, and if the true parents were able to appreciate what had happened, how much sorrow among its victims would the cuckoo cause! As a matter of fact, no sorrow at all is caused. Incredible as it may seem, the parent birds do not miss the young ones, nor do they appear to see them as they lie outside the nest. In this connection I cannot do better than quote Mr. W. H. Hudson, who was able to closely observe what happened when a young cuckoo had turned a baby robin out of the nest. “Here,” writes Hudson, “the young robin when ejected fell a distance of but five or six inches, and rested on a broad, light green leaf, where it was an exceedingly conspicuous object; and when the mother robin was on the nest—and at that stage she was on it the greater part of the time—warming that black-skinned, toad-like, spurious babe of hers, her bright, intelligent eyes were looking full at the other one, just beneath her, which she had grown in her body and had hatched with her warmth, and was her very own. I watched her for hours; watched her when warming the cuckoo, when she left the nest, and when she returned with food and warmed it again, and never once did she pay the least attention to the outcast lying there close to her. There on its green leaf it remained, growing colder by degrees, hour by hour, motionless, except when it lifted its head as if to receive food, then dropped it again, and when at intervals it twitched its body as if trying to move. During the evening even these slight motions ceased, though the feeblest flame of life was not yet extinct; but in the morning it was dead and cold and stiff; and just above it, her bright eyes upon it, the mother robin sat on the nest as before warming the cuckoo.”
Even those actions of nesting birds which appear to be most intelligent can be shown to be merely automatic. Take, for example, the curious habit of feigning injury, which some birds have, when an enemy approaches the young, in order to distract attention from them to itself and thus enable them to seek cover unobserved. This surely seems a highly intelligent act. But birds sometimes act thus before the eggs are hatched, and by so doing actually attract attention to the eggs. This action is purely instinctive, and is perpetuated and strengthened by natural selection because it is beneficial to the race.
We have seen how at the nesting season all a bird’s normal actions and instincts are subordinated to those of incubation. It is therefore but reasonable to suppose the incubating bird to be in a very peculiar and excitable state, a state bordering on insanity.
A bird in this condition might be expected to go into something resembling convulsions on the approach of an enemy, and, provided its acts under such circumstances tended to help the offspring to escape, and were at the same time not sufficiently acute to cause the mother bird to fall a victim to the enemy, natural selection would tend to perpetuate and fix such actions.
Want of space prevents further dilation upon this fascinating subject.
To sum up the conclusions I desire to emphasise. A bird has during the greater part of its life only to look after itself, and the more intelligent it be the better will it do this, hence natural selection tends to increase the intelligence of birds. But, at certain seasons, it becomes all-important to the species that the adults should attend to their young, even at risk to themselves. To secure this Nature has placed inside birds a force, dormant at most times, which at periodic intervals completely overrides all normal instincts, a force which compels parent birds to rivet their attention on the nest and its contents. Thus the sudden conversion of birds into automata is a necessity, not a mere whim of Dame Nature. The instinct is not of very long duration; for as soon as the young are able to fend for themselves, the parents sometimes behave in what seems to human beings a most unnatural way: they drive off their offspring by force. As a matter of fact, this behaviour is quite natural; it is dictated by Nature for the benefit of the species. Strong as the maternal instinct is, it is liable to be overridden by stronger instincts, such as that of migration. When the time for the migratory journey comes round, the parent birds will desert, without apparently a pang of remorse, or even a thought, the broods for whose welfare they have been slaving day and night. This desertion of later broods by migratory birds is far commoner than is generally supposed. In 1826 Mr. Blackwell inspected the house-martins’ nests under the eaves of a barn at Blakely after the autumnal migration of these birds. Of the twenty-two nests under the eaves inspected on 11th November, no fewer than thirteen were found to contain eggs and dead nestlings.
PLAYING CUCKOO
Ornithological experience led me some time back to the belief that at the nesting season a bird becomes a creature of instinct, an organism whose actions are, for the time being, those of a machine, a mere automaton. This view, which has been set forth in the preceding article, is not held by all naturalists. I therefore determined to undertake a systematic series of experiments with a view to putting it to the test. In other words, I decided to play cuckoo. I selected the Indian crow (_Corvus splendens_) as the subject of my experiments, because it is the most intelligent of the feathered folk. If it can be proved that when on the nest the actions of this bird are mechanical, it will follow that the less intelligent birds are likewise mere automata when incubating. Another reason for selecting the crow as my victim is that I have been investigating the habits of the koel (_Eudynamis honorata_), which is parasitic on the crow, and in so doing have had to visit a large number of crows’ nests.
The crow lays a pale blue egg blotched with brown, while the egg of the koel is a dull olive-green also blotched with brown. It is considerably smaller than the crow’s egg. I have seen dozens of koel’s eggs, but never one that a human being could possibly mistake for that of a crow, yet our friend _Corvus_ is unable to detect the strange egg when deposited in the nest and sits upon it. It is not that birds are colour-blind. The koel is able to distinguish its own egg from that of the crow, for, after it has deposited its egg, it frequently returns to the nest and removes one or more of the crow’s eggs! I am convinced that ordinarily a crow would have no difficulty in distinguishing between the two kinds of egg; but at the nesting time it throws most of its intelligence to the winds and becomes a puppet in the hands of its instincts, which are to sit upon everything in the nest.
I have myself placed koel’s eggs in crows’ nests, and in every case the crow has incubated the eggs. On one occasion I came upon a crow’s nest containing only two koel’s eggs. As the nest was some way from my bungalow and in an exposed situation, I knew that, the moment I left, it would be robbed by some mischievous native boy, so I took the eggs and placed them in a crow’s nest in my compound. This already contained three crow’s eggs, two of which I moved, substituting the koel’s eggs for them. The crow’s eggs had only been laid three or four days, but the koel’s eggs were nearly incubated, since both yielded chicks on the third day after I placed them in the nest. If nesting crows think, that pair must have been somewhat surprised at the speedy appearance of the chicks!
In all, I have placed six koel’s eggs in four different crow’s nests, and as I have already said, in no single instance did the trick appear to be detected. In the majority of cases, I did not trouble to keep the number of eggs in the nest constant. I merely added the koel’s egg to those already in the nest.