a sort of false bottom; but there was a small space between the bird's sides and the nest, and in this space or interstice the one unhatched egg that still remained and the young robin were lying.
During this day (29th) I observed that the pressure of the egg and young robin against his sides irritated the cuckoo: he was continually moving, jerking and wriggling his lumpish body this way and that, as if to get away from the contact. At intervals this irritation would reach its culminating point, and a series of mechanical movements would begin, all working blindly but as surely towards the end as if some devilish intelligence animated the seemingly helpless infant parasite.
Of the two objects in the nest the unhatched egg irritated him the most. The young robin was soft, it yielded when pressed, and could be made somehow to fit into the interstice; but the hard, round shell, pressing against him like a pebble, was torture to him, and at intervals became unendurable. Then would come that magical change in him, when he seemed all at once to become possessed of a preternatural power and intelligence, and then the blind struggle down in the nest would begin. And after each struggle—each round it might be called—the cuckoo would fall back again and lie in a state of collapse, as if the mysterious virtue had gone out of him. But in a very short time the pressure on his side would begin again to annoy him, then to torment him, and at last he would be wrought up to a fresh effort. Thus in a space of eight minutes I saw him struggle four separate times, with a period of collapse after each, to get rid of the robin's egg; and each struggle involved a long series of movements on his part. On each of these occasions the egg was pushed or carried up to the wrong or upper side of the nest, with the result that when the bird jerked the egg from him it rolled back into the bottom of the nest. The statement is therefore erroneous that the cuckoo knows at which side to throw the egg out. Of course he knows nothing, and, as a fact, he tries to throw the egg up as often as down the slope.
The process in each case was as follows: The pressure of the egg against the cuckoo's side, as I have said, was a constant irritation; but the irritability varied in degree in different parts of the body. On the under parts it scarcely existed; its seat was chiefly on the upper surface, beginning at the sides and increasing towards the centre, and was greatest in the hollow of the back. When, in moving, the egg got pushed up to the upper edge of his side, he would begin to fidget more and more, and this would cause it to move round, and so to increase the irritation by touching and pressing against other parts. When all the bird's efforts to get away from the object had only made matters worse, he would cease wriggling and squat down lower and lower in the bottom of the nest, and the egg, forced up, would finally roll right into the cavity in his back—the most irritable part of all. Whenever this occurred, a sudden change that was like a fit would seize the bird; he would stiffen, rise in the nest, his flabby muscles made rigid, and stand erect, his back in a horizontal position, the head hanging down, the little naked wings held up over the back. In that position he looked an ugly, lumpish negro mannikin, standing on thinnest dwarf legs, his back bent, and elbows stuck up above the hollow flat back.
Once up on his small stiffened legs he would move backwards, firmly grasping the hairs and hair-like fibres of the nest-lining, and never swerving, until the rim of the cup-like structure was reached; and then standing, with feet sometimes below and in some cases on the rim, he would jerk his body, throwing the egg off or causing it to roll off. After that he would fall back into the nest and lie quite exhausted for some time, his jelly-like body rising and falling with his breathing.
These changes in the bird strongly reminded me of a person with an epileptic fit, as I had been accustomed to see it on the pampas, where, among the gauchos, epilepsy is one of the commonest maladies;—the sudden rigidity of muscle in some weak, sickly, flabby-looking person, the powerful grip of the hand, the strength in struggling, exceeding that of a man in perfect health, and finally, when this state is over, the weakness of complete exhaustion.
I witnessed several struggles with the egg, but at last, in spite of my watchfulness, I did not see it ejected. On returning after a very short absence, I found the egg had been thrown out and had rolled down the bank, a distance of fourteen inches from the nest.
The young cuckoo appeared to rest more quietly in the nest now, but after a couple of hours the old fidgeting began again, and increased until he was in the same restless state as before. The rapid growth of the birds made the position more and more miserable for the cuckoo, since the robin, thrust against the side of the nest, would throw his head and neck across the cuckoo's back, and he could not endure being touched there. And now a fresh succession of struggles began, the whole process being just the same as when the egg was struggled with. But it was not so easy with the young bird, not because of its greater weight, but because it did not roll like the egg and settle in the middle of the back; it would fall partly on to the cuckoo's back and then slip off into the nest again. But success came at last, after many failures. The robin was lying partly across the cuckoo's neck, when, in moving its head, its little curved beak came down and rested on the very centre of that irritable hollow in the back of its foster-brother. Instantly the cuckoo pressed down into the nest, shrinking away as if hot needles had pricked him, as far as possible from the side where the robin was lying against him, and this movement of course brought the robin more and more over him, until he was thrown right upon the cuckoo's back.
Instantly the rigid fit came on, and up rose the cuckoo, as if the robin weighed no more than a feather on him; and away backwards he went, right up the nest, without a pause, and standing actually on the rim, jerked his body, causing the robin to fall off, clean away from the nest. It fell, in fact, on to a large dock leaf five inches below the rim of the nest, and rested there.
After getting rid of his burden the cuckoo continued in the same position, perfectly rigid, for a space of five or six seconds, during which it again and again violently jerked its body, as if it had the feeling of the burden on it still. Then, the fit over, it fell back, exhausted as usual.
I had been singularly fortunate in witnessing the last scene and conclusion of this little bloodless tragedy in a bird's nest, with callow nestlings for dramatis personæ, this innocent crime and wrong, which is not a wrong since the cuckoo doesn't think it one. It is a little curious to reflect that a similar act takes place annually in tens of thousands of small birds' nests all over the country, and that it is so rarely witnessed.
Marvellous as the power of the young cuckoo is when the fit is on him, it is of course limited, and when watching his actions I concluded that it would be impossible for him to eject eggs and nestlings from any thrush's nest. The blackbird's would be too deep, and as to the throstle's, he could not move backwards up the sides of the cup-like cavity on account of the smooth plastered surface.
After having seen the young robin cast out I still refrained from touching the nest, as there were yet other things to observe. One was the presence, very close to the nest, of the ejected nestling—what would the parents do in the case? Before dealing with that matter I shall conclude the history of the young cuckoo.
Having got the nest to himself he rested very quietly, and it was not till the following day (1st July) that I allowed myself to touch him. He was, I found, still irritable, and when I put back the eggs he had thrown out he was again miserable in the nest, and the struggle with the eggs was renewed until he got rid of them as before. The next day the irritability had almost gone, and in the afternoon he suffered an egg or a pebble to remain in the nest with him without jerking and wriggling about, and he made no further attempt to eject it. This observation—the loss of irritability on the fifth day after hatching—agrees with that of Mr. Craig, whose account was printed in the Feathered World, 14th July, 1899.
The young cuckoo grew rapidly and soon trod his nest into a broad platform, on which he reposed, a conspicuous object in the scanty herbage on the bank. We often visited and fed him, when he would puff up his plumage and strike savagely at our hands, but at the same time he would always gobble down the food we offered. In seventeen days after being hatched he left the nest and took up his position in
