Part 18

The situation of this nest may be said to be typical, although cases are on record of the nursery being placed on the ground at the root of a tree, or on the ledge of a rock. Many ouzels' nests are placed on the stumps of pollard trees, and in such cases the shoots which grow out of the stump often serve to hide the nest from view. The nests built by grey-winged ouzels vary considerably in structure. The commonest form is that of a massive cup, composed exteriorly of moss and lined with dry grass, a layer of mud being inserted between the moss and the grass lining. This mud layer does not invariably occur.

The cock ouzel remained for fully five minutes with one eye on me, and then flew off. I seized the opportunity to approach nearer the nest, and took up a position on the hillside level with it, at a distance of about 14 feet.

In a few minutes the hen bird appeared. Her prevailing hue is reddish brown, while the cock is black all over, save for some large patches of dark grey on the wings. In each sex the bill and legs are reddish yellow, the bill being the more brightly coloured. The hen caught sight of me and beat a hurried retreat, without approaching the nest.

The young ouzels kept very still; occasionally one of them would half raise its head. That was almost the only movement I noticed.

Presently the cock appeared, with his beak full of caterpillars. He alighted on a branch a few feet from the nest, where he caught sight of me; but instead of flying off as the hen had done, he held his ground and fixed his eye on me, no doubt swearing inwardly, but no audible sound escaped him.

Whenever I have watched a pair of birds feeding their young, I have almost invariably noticed that one of them is far more alarmed at my presence than the other. The ouzels proved no exception to the rule. In this case it was the cock who showed himself the bolder spirit. He remained watching me for fully ten minutes, his legs and body as immobile as those of a statue, but he occasionally turned his head to one side in order to obtain a better view of me; and I could then see, outlined against the sky, the wriggling forms of several caterpillars hanging from his bill. I hoped that he would pluck up courage to feed his youngsters before my eyes; but his heart failed him, for presently he flew to another tree a little farther away, whence he again contemplated me. After this he kept changing his position, never uttering a sound, and always retaining hold of the beakful of caterpillars. After a little the hen returned with her bill full of caterpillars, but she did not venture within 75 feet of the nest. I was not permitted to observe how long it would take the parental instinct to overcome the natural timidity of the birds. The sky suddenly became overcast, and a few minutes later I found myself enveloped in what the Scotch call a "wet mist." At certain seasons of the year rain storms come up as unexpectedly in the Himalayas as they do in the Grampians.

The rain put a final end to my observations on that nest, as I had to leave Naini Tal on the following day--an event which caused more sorrow to me than to the ouzels!

THE BLACK-AND-YELLOW GROSBEAK

The Indian grosbeaks are birds of limited distribution; they appear to be confined to the forests on the higher ranges of the Himalayas. Their most striking feature is the stout conical bill, which is an exaggeration of that of the typical finch, and is responsible for the bird's name. In one genus of grosbeak--Mycerobas--the bill is as deep as it is long, while in the other genus--Pycnorhamphus--it is nearly as massive. Three species belonging to this latter genus occur in India, namely, P. icteroides, the black-and-yellow grosbeak, found in the Western Himalayas; P. affinis, the allied grosbeak, found in Nepal, Sikkim, Tibet, and Western China; and P. carneipes, the white-winged grosbeak, which occurs all along the higher Himalayas.

There is only one Indian species of the other genus; this is known as the spotted-winged grosbeak (Mycerobas melanoxanthus), the localities in which this occurs are said to be "the Himalayas from the Hazara country to Sikkim at considerable elevations and Manipur."

The only Indian grosbeak which I have met in the flesh is the yellow-and-black species. This bird is common in the hills round about Murree, so that, when on ten days' leave there, I had some opportunity of studying its habits. It is a bird of the same size as the Indian oriole (Oriolus kundoo). The cock grosbeak, indeed, bears a striking resemblance to the black-headed oriole (Oriolus melanocephalus). His whole head, chin, throat, wings, shoulders, upper-tail-coverts, and thighs are black, the remainder of the plumage is a rich yellow, tinged with orange at the hind neck. Thus the colour and markings are almost identical with those of the black-headed oriole, the chief difference being that the latter has a little yellow in the wing. So great is the resemblance that the casual observer will, in nine cases out of ten, mistake the grosbeak for an oriole. The resemblance extends to size and shape, as the following table shows:

Length Length Length Length Length of Bird. of Tail. of Wing. of Tarsus. of Beak. Grosbeak . . 9.0 in. 3.7 in. 5.2 in. 1.0 in. 1.0 in. Oriole . . . 9.5 " 3.4 " 5.4 " 1.0 " 1.3 "

The hen grosbeak differs considerably in colour and marking both from the cock of her species and from the hen black-headed oriole. She is a dull ashy-grey bird, tinged faintly with yellowish red on the back and abdomen. Her wings and tail are black. The only young grosbeak that I have seen resembled the female in appearance, except that it had a yellow rump. It was being fed by a cock bird.

Grosbeaks live in forests, and go about either in couples or in small companies. They seem to feed largely on the ground, picking up insects. The beak of the finch tribe is adapted to a diet of seeds; nevertheless, many finches vary this food with insects. I saw a grosbeak seize, shake, and devour a caterpillar about two inches in length. Grosbeaks also eat berries and stone fruit. When disturbed they at once betake themselves to a tree, among the branches of which they are able to make their way with great agility. Grosbeaks are restless birds, always on the move, here to-day and gone to-morrow. The cock emits a call at frequent intervals. This is not easy to describe. It sounds something like kiu kree.

The nest is a cup-shaped structure, composed exteriorly of twigs, grass, and moss, and lined with stalks of maiden-hair fern and fine roots. It is usually placed high up in a fir tree. Colonel Rattray believes that the birds bring up two broods in the year. They lay first in May, and, as soon as the young are able to shift for themselves, a second nest is made. Thus in July both young birds at large and nests with eggs are likely to be seen. The eggs are not unlike those of the English hawfinch; the ground colour is pale greenish grey, blotched and spotted with blackish brown. Sometimes the markings occur chiefly at the broad end of the eggs.

The most striking feature of the black-and-yellow grosbeak, and that on which I wish particularly to dwell, is the extraordinary resemblance that the cock bird bears to the cock black-headed oriole. If this extended to the hen, and if the grosbeak were parasitic on the oriole, it would be held up as an example of mimicry. We should be told that owing to its resemblance to its dupe it was able to approach the nest without raising any suspicion and deposit its egg. But the grosbeak is not parasitic on the oriole, and it is the cock and not the hen that bears the resemblance; moreover, the black-headed oriole does not occur in the Himalayas, so that neither the grosbeak nor the oriole can possibly derive any benefit from this resemblance.

Now, cabinet zoologists are never tired of writing about mimicry. They assert that when organisms belonging to different families bear a close external resemblance, this resemblance has been brought about by natural selection. Having made this assertion, they expend reams of paper in demonstrating how one or both of the species benefits by the resemblance.

However, scientific books make no mention of the resemblance between the oriole and the grosbeak. The reason for this is, of course, that the resemblance in this instance cannot be a case of mimicry. Now, I regret to have to say that men of science take up the same attitude towards their theories as lawyers do regarding the cases they argue in Courts of Justice. There would be no harm in taking up this attitude if men of science were to explain that they are acting the part of advocates, that they are fighting for a theory, and trying to persuade the world to accept this theory. It is because they masquerade as judges, and put forward a one-sided case as a matured judicial finding, that I take exception to their methods.

The trouble is that scientific men to-day form a brotherhood, a hierarchy, which lays claim to infallibility, or rather tacitly assumes infallibility.

They form a league into which none are admitted except those who take the oath of allegiance; and, of course, to expose the weakness of the scientific doctrines of the time is equivalent to violating the oath of allegiance. Now, the man of science who has to earn his living by his science, has either to join the league or run the risk of starving. This explains how a small coterie of men has things very much its own way; how it can lay down the law without fear of contradiction. If a man does arise and declines to accept the fiats of this league, it is not difficult for the members to combine and tell the general public that that man is a foolish crank, who does not know what he is talking about; and the public naturally accepts this dictum.

The only scientific men who, as a class, are characterised by humility are the meteorologists. I always feel sorry for the meteorologist. He has to predict the weather, and every man is able to test the value of these predictions. The zoologist, on the other hand, does not predict anything. He merely lays down the law to people who know nothing of law. He assures the world that he can explain all organic phenomena, and the world believes him.

As a matter of fact, zoology is quite as backward as meteorology. Those who do not wish to be deceived will do well to receive with caution all the zoological theories which at present hold the field. Before many years have passed all of them will have been modified beyond recognition. Most of them are already out of date.

There are doubtless good reasons for the colouring of both the grosbeak and the oriole; what these reasons are we know not. But as neither derives any benefit from the resemblance to the other, this resemblance cannot have been effected by natural selection. Now, if the unknown forces, which cause the various organisms to take their varied colours and forms, sometimes produce two organisms of different families which closely resemble one another, and the organisms in question are so distributed that neither can derive the slightest advantage in the struggle for existence from the resemblance, there is no reason why similar resemblances should not be produced in the case of organisms which occupy the same areas of the earth. Thus it is quite possible that many so-called cases of mimicry are nothing of the kind.

The mere fact that one of the organisms in question may profit by the likeness is not sufficient to demonstrate that natural selection is responsible for the resemblance.

In this connection we must bear in mind that, according to the orthodox Darwinian theory, the resemblance must have come about gradually, and in its beginnings it cannot have profited the mimic as a resemblance.

So plastic are organisms, and so great is the number of living things in the earth, that it is not surprising that very similar forms should sometimes arise independently and in different parts of the globe. Several instances of this fortuitous resemblance are cited in Beddard's Animal Colouration; others are cited in The Making of Species by Finn, and myself.

Perhaps the most striking case is that of a cuckoo found in New Zealand, known as Eudynamis taitensis. This is a near relative of the Indian koel, which bears remarkable resemblance to an American hawk (Accipiter cooperi). Writing of this cuckoo, Sir Walter Buller says: "Not only has our cuckoo the general contour of Cooper's sparrow-hawk, but the tear-shaped markings on the underparts, and the arrow-head bars on the femoral plumes are exactly similar in both. The resemblance is carried still further, in the beautifully-banded tail and marginal wing coverts, and likewise in the distribution of colours and markings on the sides of the neck. On turning to Mr. Sharpe's description of the young male of this species in his catalogue of the Accipitres in the British Museum, it will be seen how many of the terms employed apply equally to our Eudynamis, even to the general words, 'deep brown above with a chocolate gloss, all the feathers of the upper surface broadly edged with rufous.' ... Beyond the general grouping of the colours there is nothing to remind us of our own Bush-hawk; and that there is no great protective resemblance is sufficiently manifested, from the fact that our cuckoo is persecuted on every possible occasion by the tits, which are timorous enough in the presence of a hawk."

These cases of chance resemblance should make us unwilling to talk about "mimicry," unless there is actual proof that one or other of the similar species benefits by the resemblance.