Part 21

I have taken young birds from a nest, handled them and replaced them in full view of their frantic parents. Then I have retired a short distance and watched the parents. These invariably display the same caution in approaching the nest as they did before I had discovered its whereabouts.

Birds and beasts think much less than they are popularly supposed to do. It is absurd to attribute to them reasoning powers similar to those enjoyed by man; it is equally absurd to assert that they do not think at all.

A COUPLE OF NEGLECTED CRAFTSMEN

Two Indian birds have a world-wide reputation. Every one has heard of the weaver bird (Ploceus baya) and the tailor-bird (Orthotomus sutorius). Their wonderful nests are depicted in every popular treatise on ornithology. They are both master-craftsmen and deserve their reputation. But there are in India birds who build similar nests whose very names are unknown to the great majority of Anglo-Indians. The Indian wren-warbler (Prinia inornata) weaves a nest quite as skilfully as the famous weaver bird. This neglected craftsman is common in nearly all parts of India, and, if you speak of the weaver bird to domiciled Europeans, they will think you mean this wren-warbler, for among such he is universally called the weaver bird; the famous weaver, whose portrait appears in every popular bird book, is known to them as the baya.

As its name implies, Prinia inornata is a plainly attired little bird. Its upper parts are earthy brown. It has the faintest suspicion of a white eyebrow, and its under plumage is yellowish white, the thighs being darker than the abdomen. Picture a slenderly built wren with a tail three inches in length, which looks as though it were about to fall out and which is constantly being waggled, and you have a fair idea of the appearance of this little weaver. But this description applies to dozens of other birds found in India. The various warblers are so similar to one another in appearance as to drive ornithologists to despair. The inimitable “Eha” admits that they baffle him. “There is nothing about them,” he writes, “to catch the imagination of the historian, and they will never be famous. I have been perplexed as to how to deal with them. . . . To attempt to describe each species is out of the question, for there are many, and they are mostly so like each other that even the title ornithologist does not qualify one to distinguish them with certainty at a distance. If you can distinguish them with certainty when you have them in your hand you will fully deserve the title.”

It is, however, possible to recognise the Indian wren-warbler by its note. When once you have learned this you are able to identify the bird directly it opens its mouth. But how shall I describe it? It is a peculiar, harsh but plaintive, twee, twee, twee; each twee follows close upon the preceding one, and gives you the idea that the bird is both excited and worried. If you see a fussy little bird constantly flitting about in a cornfield and uttering this note, you may be tolerably certain that the bird is the Indian wren-warbler. It never rises high in the air; it is but an indifferent exponent of the art of flying. It moves by means of laborious jerks of its wings. It is a true friend to the husbandman, since it feeds exclusively on insects. The most remarkable thing about it is its nest. This is a beautifully woven structure, composed exclusively of grass or strips of leaves of monocotyledonous plants which the bird tears off with its bill. These strands are invariably very narrow, and are sometimes less than one-twentieth of an inch in breadth. The nest may be described as an egg-shaped purse, some five or six inches in depth and three in width, with an entrance at one side, near the top. It is devoid of any lining, and its texture puts one in mind of a loosely made loofah. The nest is sometimes attached to two or more stalks of corn, or more commonly it is found among the long grasses which are so abundant in India. When the nest is built in a cornfield the birds have to bring up their family against time. They are unable to begin nest-building until the corn is fairly high, and must, if the young are to be safely started in life, have brought them to the stage when they are able to leave the nest by the time the crop is cut.

In India nearly every field of ripe corn has its family of wren-warblers; the two parents flit about, followed by a struggling family of four. These little birds do not by any means always defeat time. Numbers of their nests containing half-fledged young are mown down at every harvest by the reaper’s sickle. The nest is woven in a manner similar to that adopted by the baya; the cock and hen in each case work in combination. Its texture is looser than that of the more famous weaver, but it is not less neatly put together. In it are deposited four or five pretty little green eggs, marked with brown blotches and wavy lines.

Our second neglected craftsman is a tailor. It sews a nest so like that of the world-famous tailor as to be almost indistinguishable from it. Some authorities declare that the two nests are distinguishable. They assert that the nest of Orthotomus is invariably lined with some soft substance, such as cotton-wool, the silky down of the cotton tree, soft horse-hair, or even human hair, while that of the species of which we are speaking is lined with grass or roots. This distinction does not, however, invariably hold. I have seen nests of this species which have been lined with cotton-wool.

This bird is known to ornithologists as the ashy wren-warbler (Prinia socialis). Anglo-Indian boys call it the tom-tit. It is a dark ashy-grey bird, with the sides of the head and neck and the whole of the lower plumage buff. There is a tinge of rufous in the wings and tail. It is most easily distinguished by the loud snapping noise it makes during flight. How this noise is produced we do not know for certain. Reid was of opinion that the bird snapped its long tail. What exactly this means I do not know. Jesse believes that the sound is produced by the bird’s mandibles. I have spent much time in watching the bird, and am inclined to think that the noise is caused by the beating of the wings against the tail. This last is constantly being wagged and jerked, and it seems to me that the wings beat against it as the bird flits about. When doves and pigeons fly, their wings frequently meet, causing a flapping sound. I am of opinion that something similar occurs when the ashy wren-warbler takes to its wings.

Perhaps the most extraordinary thing about this bird is the well-authenticated fact that it builds two types of nest. Besides this tailor-made nest, the species makes one of grass, beautifully and closely woven, domed, and with the entrance near the top. I have never seen this latter type of nest, but so many ornithologists have that there can be no doubt of its existence.

The strange thing is that both types of nest have been found in the same neighbourhood, so that the difference in the form of nursery is not a local peculiarity.

I am at a loss to account for the existence of these two types of nest. I have no idea how the habit can have arisen, nor do I know what, if any, benefit the species derives from this peculiarity. So far as I am aware, no one can say what it is that leads to the construction of one type of nest in preference to the other. The nests of this species present a most interesting ornithological problem. I hope one day to be in a position to throw some light on it; meanwhile I shall welcome the news that some one has forestalled me. The ashy wren-warbler is a common bird, so that most Anglo-Indians have a chance of investigating the mystery. The same kind of eggs are found in each type of nest. They are of exceptional beauty, being a deep mahogany or brick-red, so highly polished as to look as though they have been varnished.

BIRDS IN THEIR NESTS

Just as every Englishman is of opinion that his house is his castle, so does every little bird resent all attempts at prying into its private affairs in the nest. For this reason we really know very little of the home-life of birds. It is not that there are no seekers after such knowledge. Practical ornithology is a science that can boast of a very large number of devotees.

Many men spend the greater part of their life in endeavouring to wrest from birds some of their secrets, and such must admit that the results they obtain are as a rule totally disproportionate to the magnitude of the efforts. At present we know only the vague generalities of bird life.

We know that the hen lays eggs; that she, with or without the help of the cock, as the case may be, incubates these eggs; that the young, which are at first naked, are fed and brooded until they are ready to leave the nest, when they are coaxed forth by the parents, who hold out tempting morsels of food to them. But these are mere generalities. Our ignorance of details is very great.

The nests of most passerine birds are scrupulously clean. Young birds have enormous appetites, and much of the food which they eat is indigestible and must pass out as droppings, yet in the case of many species no sign of these droppings is visible, either in the nest, or on the leaves, branches, or the ground near the nest. What becomes of these droppings? Ornithological treatises are silent upon this subject.

Again, young birds are born naked, and in India are frequently exposed to very high temperatures, so that much liquid must pass from their bodies by evaporation. How is this liquid made good? Do the parents water the birds, if so, how? I have never seen any mention of this in an ornithological treatise.

Let us to-day consider these two subjects: the sanitation of the nest and the method of assuaging the thirst of young nestlings.

As regards the first we have some knowledge, thanks to the patient labours of Mr. F. H. Herrick, an American naturalist, whose book, The Home Life of Birds, I commend to every lover of the feathered folk. Unfortunately, Mr. Herrick’s book is to some extent spoiled for Englishmen, because it deals with birds with which they are unfamiliar; nevertheless, its general results apply to all passerine birds.

Mr. Herrick is a very keen bird photographer. As every one knows, he who wishes to obtain good photographs of birds has two great difficulties to overcome. The first is to get near to his subjects, and the second is to find them and their nests in situations suitable for photography.

The former is usually overcome by the photographer concealing himself and his camera in a tent or other structure. At first the birds are afraid of the concealing object, but soon maternal affection overcomes their fear.

Mr. Herrick’s method of overcoming the second of these two difficulties is to remove the nest to be photographed from the concealed situation in which it is usually built, and place it in a more open place. If the nest be thus moved when the young are some seven or eight days old, the parents will almost invariably continue to feed their young in the new situation, for at that particular period the parental instinct is at its zenith. In addition to obtaining a splendid series of photographs, Mr. Herrick has observed, from a distance of a few inches, the nesting habits of several American birds. As the result of these observations he is able to declare that nest-cleaning follows each feeding with clock-like regularity. “The excreta of the young,” he writes, “leave the cloaca in the form of white opaque or transparent mucous sacs. The sac is probably secreted at the lower end of the alimentary canal, and is sufficiently consistent to admit of being picked up without soiling bill or fingers. The parent birds often leave the nest hurriedly bearing one of these small white packages in bill, an action full of significance to every member of the family. . . . Removing the excreta piecemeal and dropping it at a safe distance is the common instinctive method, not only of insuring the sanitary condition of the nest itself, but, what is even more important, of keeping the grass and leaves below free from any sign which might betray them to an enemy.” These packets of excrement are quite odourless, and they are often devoured by the parent bird instead of being carried away. The digestion of very young birds must be feeble, and doubtless much of the food given them passes undigested through the alimentary canal, so that it is capable of affording nourishment to the parents. Birds are nothing if not economical.

Of course, all birds are not so careful of the sanitation of the nest. Every one knows what a filthy spectacle a heronry is. According to Mr. Herrick, the instinct of inspecting and cleaning the nest is mainly confined to the great passerine and picarian orders. It is obviously not necessary in the case of those birds, such as fowls, of which the young are able to run about when born; nor is it needful in the case of birds of prey, who take no pains to conceal the whereabouts of the nest. Young raptores eject their semi-fluid excreta over the edge of the nursery; thus the nest is kept clean, but the droppings on the ground betray its presence to all the world.

Coming now to our other question: How do young birds obtain the water which they require? we have no help from Mr. Herrick. He makes no mention of this in his most interesting book. It is possible that nestlings are not given anything to drink, that the juicy, succulent insects or fruits with which they are supplied contain sufficient moisture for their requirements. We must remember that the skin of birds is very different from that of man. It contains no sweat glands, so that a bird, like a dog, can only perspire through its mouth.

The breath of mammals is so surcharged with moisture that when it is suddenly cooled the water vapour in it condenses; the result is we can “see the breath” of a mammal on a cold day. I have never succeeded in seeing a bird’s breath, so am of opinion that the fowls of the air do not exhale so much moisture as mammals do. But even allowing for this, a considerable amount of moisture must be given out in expiration, so that it seems probable that young birds require more moisture than they obtain in their food. Drops of water have to be administered to hand-reared birds. Many birds fill up the crop with food and then discharge the contents into the gaping mouths of their young. In this condition the food must be mixed with a considerable quantity of saliva and possibly with water. The crop of a bird is a receptacle into which the food passes and remains until actually utilised. There seems no reason why water should not be stored for a short time in this receptacle just as food is. Perhaps birds “bring up” water as they do solid food, and thus assuage the thirst of their young. Such a process would be very difficult to detect; it would be indistinguishable from ordinary feeding to the casual observer. I hope that some physiologist will take up the matter. A quantitative analysis of the air exhaled by a bird should not be very difficult to make.

BULBULS

More than fifty species of bulbul are found in India—bulbuls of all sorts and conditions, of all shapes and sizes, from the brilliant green bulbuls (which, by the way, strictly speaking, are not bulbuls at all) to the dull-plumaged but blithe white-browed member of the community, so common in Madras; from the rowdy black bulbuls of the Himalayas to the highly respectable and well-behaved red-vented bulbuls. He who would write of them is thus confronted with an embarras de richesses. The problem that he has to solve is, which of the many species to take as his theme.