Glimpses of Indian Birds

by Douglas Dewar

BULBULS’ NESTS—II

The simplest observations often bring to light the greatest scientific truths. The force of gravity was revealed to Sir Isaac Newton by the falling of an apple. A kettle of boiling water gave the idea of the steam-engine to James Watt. The watching of bulbuls, which are so common in our Indian gardens and verandahs, suffices, apart from all other evidence, to demonstrate how erroneous is the orthodox doctrine that the survival of the fittest is the result of a struggle for existence among adult organisms. This year (1912) six bulbul tragedies have occurred in my garden, and the year is yet young.

The scene of one of these tragedies was the identical plant in which occurred the disaster described above, which happened about nine months ago. Thus we see that among bulbuls destruction takes place mostly in the nest, whole broods being wiped out at a time. The same is, I believe, true to a large extent of other species that build open nests. There are three critical stages in the life of a bird—the time when it is defenceless in the egg, the period it spends helpless in the nest, and the two or three days that elapse after it leaves the nest until its powers of flight are fully developed. When once a little bird has survived these dangerous periods, when it has reached the adult stage, it is comparatively immune from death until old age steals upon it. If zoologists would perceive this obvious truth there would be an end to nine-tenths of the nonsense written about protective colouring. Most birds are not protectively coloured; moreover, if they were so clothed as to be invisible amid their natural surroundings they would not derive much profit therefrom.

The labour of the six-and-twenty little bulbuls who, to my knowledge, have failed to rear their broods has not been lost altogether, for it has taught me something about their ways that I did not know before. Those birds showed me how quickly they are able to build a nest.

Very few observations regarding the duration of nest-building operations are on record. The reason is not far to seek. A nest at the very beginning of its existence is difficult to discover, and if come upon by chance is not easy to recognise as an incipient nursery. The nests we find are usually complete or in an advanced stage of construction.

I was strolling in the garden about 8 a.m. on the 3rd March last, when I noticed a bulbul with a leaf in its bill. I saw the bird fly into a small cypress bush and then emerge therefrom without the leaf. A short search sufficed to reveal the place in the bush where the leaf had been deposited. Placed by this leaf I found another leaf, a small branch of Duranta with some yellow berries attached to it, two or three small straws and some cobweb. These apparently had been thrown haphazard into the bush. Had I not seen the bulbul go into the bush carrying a leaf, I should not have suspected that these few things were the beginning of a nest, for they had no semblance of one. The bulbuls could not have been working at that nest for more than half an hour when I discovered it. On my return thirty minutes later to look at it I found that the amount of material collected had doubled, but the nest was still without any definite form; it was a mere conglomeration of rubbish. The two leaves already mentioned had dropped down nearly a couple of inches below the other material. The additional material consisted of more Duranta twigs with berries, straws, dried grasses, cobweb, and a piece of what looked like tissue paper. Half an hour later the rapidly increasing collection included a long piece of worsted, but this was not wound round any of the branches. In most bulbuls’ nests that I have seen a certain amount of cotton or such-like material is used to support the cup-like nest by being bound to one of the neighbouring branches, although cobweb is the chief means of attaching the nest to its surroundings. In this particular instance, however, the worsted was not so utilised; possibly the pliable, upright branches of the cypress did not lend themselves to this kind of attachment. At this time (9 a.m.) the collected materials had nothing of the shape of a nest, but some of the tiny twigs were entwined in the cypress branches.

At midday, four hours after I had first seen the nest, I was astonished to find that it had assumed a saucer-like form. I was not a witness of the process whereby the original shapeless mass was made to take this shape, but my observations on other nests have convinced me that the nest is shaped entirely by the bird’s body and feet. When a bulbul brings material to the nest, it drops this on to what has already been collected, sits on it, and proceeds to arrange it with its feet, which work so vigorously as to shake the whole plant in which the nest is placed. In the middle of the process the bird usually turns on its axis, a right angle, and thus the interior of the nest becomes rounded by the bird’s breast. All new material is added to the inside of the nest.

At midday, then, the nest in question was a shallow saucer composed chiefly of Duranta and other twigs, dried grass, and bast. The leaves mentioned above had fallen some way below the nest, and the worsted and tissue paper had been crushed into a ball at one side of the nest.

By the evening more material, chiefly bast in bands about a quarter of an inch broad, had been added, and the nest looked almost as complete as some bulbuls’ nests in which I have seen eggs. But that particular pair were evidently bent on building a very substantial structure.

By 8 a.m. on the following day the cup of the nest had grown deeper, and its walls had been considerably thickened. By the evening of the day the nest was practically complete. On the 5th March the finishing touches were put to it in the shape of a few grasses and prickly stems.