At length, however, the young pair find the necessity of going more regularly to work. While one flies to fetch the materials, the other sits upon the tree to guard it; and thus in the space of three or four days, with a skirmish now and then between, the pair have filled up a commodious nest, composed of sticks without, and of fibrous roots and long grass within. From the instant the female begins to lay, all hostilities are at an end; not one of the whole grove, that a little before treated her so rudely, will now venture to molest her, so that she brings forth her brood with perfect tranquillity. Such is the severity with which even native rooks are treated by each other; but if a foreign rook should attempt to make himself a denizen of their society, he would meet with no favour, the whole grove would at once be up in arms against him, and expel him without mercy.
Couch says ('Illustrations of Instinct,' p. 334 et seq.):—
The wrong-doers being discovered, the punishment is appropriate to the offence; by the destruction of their dishonest work they are taught that they who build must find their own bricks or sticks, and not their neighbours', and that if they wish to live in the enjoyment of the advantages of the social condition, they must endeavour to conform their actions to the principles of the rookery of which they have been made members.
It is not known what enormities led to the institution of another tribunal of the same kind, called the Crow Court, but according to Dr. Edmonson, in his 'View of the Shetland Islands,' its proceedings are as authoritative and regular, and it is remarkable as occurring in a species (Corvus Cornice) so near akin to the rook. The Crow Court is a sort of general assembling of birds who, in their usual habits, are accustomed to live in pairs, scattered at great distances from each other; when they visit the south or west of England, as they do in severe winters, they are commonly solitary. In their summer haunts in the Shetland Islands, numbers meet together from different points on a particular hill or field; and on these occasions the assembly is not complete, and does not begin its business for a day or two, till, all the deputies having arrived, a general clamour or croaking ensues, and the whole of the court, judges, barristers, ushers, audience, and all, fall upon the two or three prisoners at the bar, and beat them till they kill them. When this is accomplished the court breaks up and quietly disperses.
In the northern parts of Scotland (says Dr. Edmonson), and in the Faroe Islands, extraordinary meetings of crows are occasionally known to occur. They collect in great numbers, as if they had all been summoned for the occasion; a few of the flock sit with drooping heads, and others seem as grave as judges, while others again are exceedingly active and noisy; in the course of about one hour they disperse, and it is not uncommon, after they have flown away, to find one or two left dead on the spot. These meetings will sometimes continue for a day or two before the object, whatever it may be, is completed. Crows continue to arrive from all quarters during the session. As soon as they have all arrived, a very general noise ensues; and, shortly after, the whole fall upon one or two individuals, and put them to death. When the execution has been performed, they quietly disperse.
Similarly, the Bishop of Carlisle writes in the 'Nineteenth Century' for July 1881:—
I have seen also a jackdaw in the midst of a congregation of rooks, apparently being tried for some misdemeanour. First Jack made a speech, which was answered by a general cawing of the rooks; this subsiding, Jack again took up his parable, and the rooks in their turn replied in chorus. After a time the business, whatever it was, appeared to be settled satisfactorily: if Jack was on his trial, as he seemed to be, he was honourably acquitted by acclamation; for he went to his home in the towers of Ely Cathedral, and the rooks also went their way.
Lastly, Major-General Sir George Le Grand Jacob, K.C.S.I., C.B., writes to me that while sitting in a verandah in India, he saw three or four crows come and perch on a neighbouring house. They then cawed continuously with such peculiar sound and vigour as to attract his attention. His account proceeds:—
Soon a gathering of crows from all quarters took place, until the roof of the guard-house was blackened by them. Thereupon a prodigious clatter ensued; it was plain that a 'palaver' was going forward. Some of its members, more eager than others, skipping about, I became much interested, and narrowly watched the proceedings, all within a dozen yards of me. After much cawing and clamour, the whole group suddenly rose into the air, and kept circling round half a dozen of their fellows, one of whom had been clearly told off for punishment, for the five repeatedly attacked it in quick succession, allowing no opportunity for their victim to escape, which he was trying to do, until they had cast him fluttering on the ground about thirty yards from my chair. Unfortunately I rushed forward to pick up the bird, prostrate but fluttering on the grass which was like a lawn before the building. I succeeded only in touching it, for it wriggled away from my grasp, and flew greatly crippled and close to the ground into the neighbouring bushes, where I lost sight of it. All the others, after circling round me and chattering, angrily as I thought, flew away, on my resuming my seat, in the direction taken by their victim.
[Since going to press I have seen, through the kindness of Mr. Seebohm, some specimens of cuckoo's eggs coloured in imitation of those belonging to the birds in the nests of which they are laid. There can be no question about the imitation, and I add this note to mitigate the criticism which I have passed upon Professor Newton's theory of the cause. For Mr. Seebohm has pointed out to me that the theory becomes more probable if we consider that a cuckoo reared in the nest of any particular bird is likely afterwards to choose a similar nest for the deposition of its own eggs. Whether or not the memory of a bird would thus act could only, of course, be certainly proved by experiment; but in view of the possibility that it may, Professor Newton's theory becomes more probable than it is if the selection of the appropriate nest is supposed to depend only on inheritance.