Part 8
But I have put my theory to a much more severe test. In a certain crow’s nest containing two eggs I put a large fowl’s egg. This was cream-coloured and fully three times the size of the crow’s egg, yet within ten minutes the crow was sitting comfortably on the strange egg. She did not appear to notice the considerable addition to her clutch. She subsequently laid three more eggs, so that she had six eggs to sit upon, five of her own and the large fowl’s egg! Day after day I visited the nest and watched the progress of the strange egg. On the twentieth day the chick inside was moving, but when I went to the nest on the twenty-first day I discovered that some one had climbed the tree, for several branches were broken. Two young crows had been taken away and the fowl’s egg thrown upon the ground. There it lay with a fully formed black chicken inside! I have that chicken in a bottle of spirit. Subsequent inquiry showed that the _dhobi’s_ son had taken it upon himself to spoil my experiment. However, it went sufficiently far to prove that crows may one day become birds of economic value; why not employ them as incubators? Had the crow come across that chick’s egg anywhere but in its nest, it would undoubtedly have made its breakfast off it.
I repeated the experiment in another nest. This time the chick hatched out. When it appeared the rage of the crows knew no bounds. With angry squawks the scandalised birds attacked the unfortunate chick, and so viciously did they peck at it that it was in a dying state by the time my climber reached the nest.
With a view to determining at what stage the incubating instinct secures its dominance, I placed another fowl’s egg in a crow’s nest that was almost ready to receive eggs, wondering whether the presence of this egg would stimulate the crow to lay, without troubling to give the final touches to the nest. The bird devoured the egg. It is my belief that the acts of a nesting bird do not become completely automatic until it has laid an egg in the nest. If one visits a crow’s nest which is in course of construction, the owners will as likely as not desert it; but I have never known a crow desert its nest when once it has laid an egg—provided, of course, he who visits the nest leaves any eggs in it.
In another nest containing two crow’s eggs I placed a golf ball; on returning next day I found the crow sitting tight upon her own two eggs and the golf ball!
But in another case, where I had found two eggs and substituted for them a couple of golf balls, the crow refused to sit. I suppose the idea was, “I may be a bit of a fool when I am nesting, but I am not such a fool as all that!” I once came across a young koel and a crow’s egg in a nest. I removed the former and placed it in a crow’s nest containing four crow’s eggs. The owner of the nest showed no surprise at the sudden appearance of the koel, but set about feeding it in the most matter-of-fact way. The young koel was successfully reared; it is now at large and will next year victimise some crow. I may say that no human being could possibly fail to distinguish between a young koel and a young crow. When first hatched the koel has a black skin, the crow a pink one. The mouth of the crow nestling is an enormous triangle with great fleshy flaps at the side; the mouth of the koel is much smaller and lacks the flaps. The feathers arise very differently in each species, and whereas those of the crow are black, those of the koel are tipped with russet in the cock and white in the hen.
In another nest containing a young koel (put there by me) and two crow’s eggs, I placed a paddy bird’s (_Ardeola grayii_) egg, hoping that the gallant crow would hatch it out and appreciate the many-sidedness of her family. She hatched out the egg all right, at least I believe she did. I saw it in the nest the day before the young paddy bird was due; but when I visited the nest the following morning neither egg nor young bird was there. It would seem that the crow did not appreciate the appearance of the latest addition to the family and destroyed it. It is, of course, possible that the young koel declined to associate with such a neighbour and killed it; but I think that the crow was the culprit, for I had previously placed a paddy bird nestling, four days old, in a crow’s nest containing only young crows, and the paddy bird had similarly disappeared.
These, then, are the main facts which my game of cuckoo has brought to light. They are not so decisive as I had expected. They seem to indicate that the actions of birds with eggs or young are not quite so mechanical as I had supposed. Were they not largely mechanical a crow would never hatch out a koel’s egg, nor would it feed the young koel when hatched out; it would not incubate a fowl’s or a paddy bird’s egg, and it would assuredly decline to sit upon a golf ball. On the other hand, were the acts of nesting birds altogether mechanical, the young paddy birds would have been reared up, and the substitution of two golf balls for two eggs would not have been detected. There is apparently a limit to the extent to which intelligence is subservient to blind instinct.
THE KOEL
Anglo-Indians frequently confound the koel with the brain-fever bird. There is certainly some excuse for the mistake, for both are cuckoos and both exceedingly noisy creatures; but the cry of the koel (_Eudynamis honorata_) bears to that of the brain-fever bird or hawk-cuckoo (_Hierococcyx varius_) much the same relation as the melody of the organ-grinder does to that of a full German band. Most men are willing to offer either the solitary Italian or the Teutonic gang a penny to go into the next street, but, if forced to choose between them, select the organ-grinder as the lesser of the two evils. In the same way, most people find the fluty note of the koel less obnoxious than the shriek of the hawk-cuckoo.
The latter utters a treble note, which sounds like “Brain fever.” This it is never tired of repeating. It commences low down the musical scale and then ascends higher and higher until you think the bird must burst. But it never does burst. When the top note is reached the exercise is repeated.
The koel is a bird of many cries. As it does not, like the brain-fever bird, talk English, its notes are not easy to reproduce on paper. Its commonest call is a crescendo _kuil, kuil, kuil_, from which the bird derives its popular name. This cry is peculiar to the cock. The second note is, to use the words of Colonel Cunningham, “an outrageous torrent of shouts, sounding like _kūk, kŭū, kŭū, kŭū, kŭū, kŭū_, repeated at brief intervals in tones loud enough to rouse the ‘Seven Sleepers.’” The koel is nothing if not impressive. He likes to utter this note just before dawn, when all the world is still. As the bird calls chiefly in the hot weather, when it frequently happens that the hour before sunrise is almost the only one in the twenty-four in which the jaded European can sleep, this note is productive of much evil language on the part of the aforesaid European.
The koel’s third cry is well described by Cunningham as a mere cataract of shrill shrieks—_heekaree, karees_. This is heard mostly when the hen is fleeing for dear life before a pair of outraged crows. So much for the voice of the koel, now for a description of the singer. The cock is a jet-black bird with a green bill and a red eye. The hen is speckled black and white, with the eye and beak as in the cock. Add to this the fact that the koel is a little larger than the “merry cuckoo, messenger of spring” which visits England, and it is impossible not to recognise the bird.
This cuckoo, like many of its relatives, does not hatch its own eggs. It cuckolds crows. This is no mean performance, for the crow is a suspicious creature. It knoweth full well the evil which is in its own heart, and so, judging others by itself, watches unceasingly over its nest from the time the first egg is deposited therein until the hour when the most backward young one is able to fly. Now, a koel is no match for a crow in open fight, hence it is quite useless for the former to attempt by means of force to introduce its egg into the crow’s nest. It is obliged to resort to guile. The cock entices away the crows, and while they are absent the hen deposits her egg.
Crows appear to dislike the cry of the koel quite as much as men do. But whereas man is usually content with swearing at the noisy cuckoo, crows attack it with beak and claw whenever an opportunity offers. This fact is turned to account by the koel. The cock alights in a tree near a crow’s nest and begins to call. The owners of the nest, sooner or later, “go for” him. He then takes to his wings, continuing to call, so as to induce the crows to prolong the chase. As he is a more rapid flier than they, he does not run much risk. While the irate corvi are in pursuit, the hen koel, who has been lurking around, slips into the nest and there lays her egg. If she is given time she destroys one or more of those already in the nest. She does this, not because the crows would detect the presence of an additional egg, but in order that her young, when hatched, will not be starved owing to the large number of mouths to feed.
Crows, although such clever birds, are, as we have seen, remarkably stupid at the nesting season. They are unable to distinguish the koel’s egg from their own, although the former is considerably smaller, with an olive-green background instead of a bluish one; and when the young koel emerges from the egg, they are unable to differentiate between it and their own offspring, although baby koels are black and baby crows pink, when first hatched out. The koel nestling has one point in common with young crows, and that is a large mouth of which the inside is red. This is opened wide whenever a parent approaches, so that the latter sees nothing but a number of yawning caverns; thus there is some excuse for its failure to distinguish between the true and the spurious nestlings.
To return to the koel who is laying her egg in the momentarily deserted nest. She does not carry her egg thither in her beak as the common cuckoo is said to do, but sits in the nest and lays it there. Sometimes the crows return before she is ready and, of course, attack her, but as she can fly faster than they, they do not often succeed in harming her, although there are instances on record of crows mobbing female koels to death. It will thus be seen that cuckolding crows is dangerous work. The life of the cuckoo is not all beer and skittles, and the birds seem to feel the danger of their existence, for at the breeding season they appear to be in a most excited state, and are manifestly afraid of the crows. This being so, I am inclined to think that the latter are responsible for the parasitic habit of the koel. It is not improbably a case of the biter bit. Crows are such aggressive birds that they are quite capable of evicting any other bird from its nest if this be large enough to suit their purpose. Now suppose a koel to be thus evicted by force when ready to lay; it is quite conceivable that she might make frantic efforts to lay in her rightful nest, and if she succeeded, and the crows failed to detect her egg, they would hatch out her offspring. If the koels which acted thus managed to have their offspring reared for them, while those that attempted to build fresh nests dropped their eggs before the new nurseries were ready, natural selection would tend to weed out the latter and thus the parasitic habit might arise, until eventually the koel came to forget how to build a nest.
In this connection it is important to bear in mind that the nearest relatives of the koel are non-parasitic. It is therefore not improbable that in the koel the parasitic habit has an independent origin.
This instinct has undoubtedly been evolved more than once. It does not necessarily follow that similar causes have led to its origin in each case.
The suggestion I have made is made only with reference to the koel, which differs from other cuckoos in that it dupes a bird stronger and bigger than itself. But this is a digression.
If the koel have time, she destroys one or more of the existing eggs, and will sometimes return later and destroy others. Although the crow cannot distinguish between her own and koel’s eggs, the koel can. I have come across several crows’ nests which each contained only two koel’s eggs.
The young koel is a better-behaved bird than some of its relations, for it ejects neither the eggs still in the nest when it is hatched nor its foster-brethren. But the incubating period of the koel is shorter than that of the crow, so that the koel’s egg is always the first to hatch out. The koel seems never to make the mistake of depositing its egg among nearly incubated ones. Thus the young koel commences life with a useful start on its foster-brethren. It soon increases this start, as it grows very fast, and is ready to fly before the earliest feathers of its foster-brothers are out of their sheaths.
It does not, however, leave its foster-parents when able to fly. It sits on the edge of the nest and makes laudable, if ludicrous, efforts at cawing. The crows continue feeding it long after it has left the nest, looking after it with the utmost solicitude. A young koel is somewhat lacking in intelligence; it seems unable to distinguish its foster-parents from any other crow, for it opens its mouth at the approach of every crow, evidently expecting to be fed.
The natives of the Punjab assert that the hen koel keeps her eye on the crow’s nest in which she has laid her egg or eggs during the whole of the time that the young cuckoo is in it, and takes charge of her babe after it leaves the nest. This assertion appears to be incorrect. I have never seen a koel feeding anything but itself. Moreover, the koel lays four or five eggs, and these are not usually all deposited in one nest. It would therefore be exceedingly difficult, if not impossible, for the hen to keep an eye on each of her eggs.
In view of the hatred which crows display towards koels in general, naturalists have expressed surprise that the young koels are not mobbed directly they leave the nest. Their plumage differs in no way from that of the adult. It has been suggested that young koels retain the crow smell for a considerable time after they are fledged. This I cannot accept. The olfactory organ of birds is but slightly developed. Indeed, I am inclined to wonder whether birds have any sense of smell. The truth of the matter is that crows look after their foster-children most carefully for several weeks after they have left the nest, and see that no strange crow harms them.
THE COMMON DOVE OF INDIA
The dove family ought to have become extinct ages ago, if all that orthodox zoologists tell us about the fierce struggle for existence be true. They form a regular “Thirteen Society.” They do everything they should not do, they disobey every rule of animal warfare, they fall asleep when sitting exposed on a telegraph wire, they build nests in all manner of foolish places, their nests are about as unsafe as a nursery can possibly be, and they flatly decline to lay protectively coloured eggs—their white eggs are a standing invitation to bird robbers to indulge, like the Cambridge crew of 1906, in an egg diet; yet, in spite all of these foolhardy acts, doves flourish like the green bay tree. This is a fact of which I require an explanation before I can accept all the doctrines of the Neo-Darwinian school.
There are so many species of dove in India that when speaking of them one must perforce, unless one be writing a great monograph, confine oneself to two or three of the common species. I propose to-day to talk about our three commonest Indian doves, that is to say, the spotted dove (_Turtur suratensis_), the Indian ring-dove (_Turtur risorius_), and the little brown dove (_Turtur cambayensis_). I make no apology for discoursing upon these common species. I contend that we in India know so very little about even our everyday birds that it is a needless expenditure of energy to seek out the rarer species and study their habits; we have plenty to learn about those that come into our verandahs and coo to us.
The curious distribution of our common Indian doves has not, so far as I know, been explained. In very few places are all three common. One or other of them is usually far more abundant than the others, and this one is usually the spotted dove. It is the commonest dove of Calcutta, of Madras, of Travancore, of Tirhoot, of Lucknow, but not of Lahore or Bombay or the Deccan. Why is this? Why is it that, whereas the Deccan is literally overrun by the ring- and the little brown dove, one can go from Bombay to Malabar without meeting one of these species, but seeing thousands of the spotted dove?
The only explanation that I can offer of this phenomenon is that the spotted dove is the most pugnacious and the most pushing; that where he chooses to settle down he ousts the other species of dove more or less completely; but he, fortunately for the other species, does not choose to settle down in all parts of India. He objects to dry places. Hence he is not seen at Lahore or in the Deccan, or in the drier parts of the United Provinces, such as Agra, Muttra, Etawah, and Cawnpore.
This is only a theory of mine, and a theory in favour of which I am not able to adduce very much evidence, since my personal knowledge of India is confined to some half-a-dozen widely separated places. Moreover, this theory does not explain the absence of the spotted dove from Bombay. I should be very glad to know if there are any other moist parts of India where the spotted dove is not the most abundant of the cooing family.
The nest of the dove is a subject over which most ornithologists have waxed sarcastic. A more ramshackle structure does not exist; yet the absurd thing is that doves are most particular about the materials they use.
The other day I watched, with much amusement, a little brown dove at work nest building. It was constructing a shake-down in a small Lonicera bush. Now, obviously, since the nest is just a few twigs and stalks thrown together, any kind of short twig or stem will serve for building material. This, however, was not the view of the dove. If that creature had been constructing the Forth Bridge it could not have been more particular as regards the materials it picked up. It strutted about the ground, taking into its bill all manner of material only to reject it, until at last it picked up a dead grass stalk and flew off with it in triumph!
Presumably doves take the same trouble in selecting a site for their nest, nevertheless they sometimes eventually choose the most impossible spot. Thus Mr. A. Anderson has recorded the existence of a nest of a pair of little brown doves that “was placed close to the fringe of the _kunnaut_ of his tent on one of the corner ropes, where it is double for some six inches and there knotted. The double portion was just broad enough, being three inches apart, to support the nest with careful balancing; the _knot_ acted as a sort of _buffer_ and prevented the twigs from sliding off, which most assuredly would otherwise have been the case, for the rope just there was at an angle of 45°.”
Those foolish birds were not permitted to bring up their young, because the tent had to be struck before the eggs were laid.
In Lahore a favourite nesting site for the little brown dove is on the top of the rolled-up portion of the verandah _chik_. As the _chik_ is composed of stout material, the rolled-up portion forms an excellent platform some four inches broad. But as the doves nest just as the weather is beginning to grow warm, the little home is apt to be somewhat rudely broken up. One pair, however, has this year successfully reared up two young hopefuls in a nest on this somewhat precarious site. The doings of these form the subject of the next article.
I once came across a nest of this little dove in a low, prickly bush beside a small canal distributory, three miles outside Lahore. The dove appeared to have used as the foundation for its nest an old one of the striated bush babbler (_Argya caudata_). (I object to calling this bird the common babbler, since, like common sense, it is not very common.) In the same bush, at the same level, that is to say, about a yard from the ground and only a couple of feet from the dove’s nest, was that of a striated bush babbler containing three dark blue eggs. This is a case upon which those who believe that eggs laid in open nests are protectively coloured would do well to ponder.
There, side by side, in precisely the same environment, were two nests—one containing white and the other dark blue eggs. Obviously both sets of eggs could not be protectively coloured; as a matter of fact, both clutches of eggs were conspicuous objects. It not infrequently happens that the Indian robin (_Thamnobia cambayensis_), which lays white eggs thickly spotted with reddish brown, brings up a family in a disused nest of a striated bush babbler’s. The eggs of this latter are dark blue. It is surely time that zoologists gave up throwing at us their everlasting theory of protective colouring. If this were a _sine qua non_ of the safety of birds’ eggs, then the whole dove tribe would, long ago, have ceased to exist.
This family presents the ornithologist with yet another problem in colouration. In every species, except the red turtle-dove (_Oenopopelia tranquebarica_), both sexes are coloured alike. In this latter, however, there is very pronounced sexual dimorphism. The ruddy wing feathers of the cock enable one to distinguish him at once from his mate and from every other dove. Now the habits of this dove appear to be exactly like those of all other species. It constructs the same kind of nest and in similar situations; why then the sexual dimorphism in this species and in no other species? If the lady rufous turtle-dove likes nice ruddy wings, and thus the red wing has been evolved in the cock bird, why has she too not inherited it? I presume that even the most audacious Neo-Darwinian will not talk about her greater need of protection when sitting on the nest, for if she needs protection, how much more so do her white eggs? Further, it is my belief that the cock bird takes his turn in the incubation.
It must not be thought that I am needlessly poking fun at modern biologists. I merely desire to call attention to the unsolved problems that confront us on all sides, and to protest against the dogmatism of biology which declares that the Darwinian theory explains the whole of organic nature. As a matter of fact, it seems to me that the field naturalist cannot but feel that natural selection is turning out rather a failure.
In conclusion, one more word regarding the red turtle-dove. Its distribution has not been carefully worked out, and what we do know of it is not easy to explain. Hume says that it breeds in all parts of India, but is very capriciously distributed, and he is unable to say what kind of country it prefers, and why it is common in one district and rare in a neighbouring one in which all physical conditions appear identical.
It is very common in the bare, arid, treeless region that surrounds the Sambhur Lake. It is common in some dry, well-cultivated districts, like Etawah, where there are plenty of old mango groves. It is very common in some of the comparatively humid tracts, like Bareilly, and again in the _sal_ jungles of the Kumaun _Bhabar_ and the Nepal _Terai_. On the other hand, over wide extents of similar country it is scarcely to be seen. Doubtless there is something in its food or manner of life that limits its distribution, but no one has yet been able to make out what this something is.
DOVES IN A VERANDAH