[Following from discussion of flock-manoeuvres of starling, gull, etc.]
In autumn rooks and jackdaws may be seen wheeling in a similar manner above their roosting places, rising higher and higher at every turn and calling noisily the while. In their case I have sometimes thought that the game or dance was an attempt by some of the bolder spirits to organise a migration or an expedition of some kind, for it is clear that there is usually much difference of opinion among them. Some seem to wish to start at once, for they set off in a direct flight, but they soon return to the flock, most of whom are still undecidedly wheeling "about it and about," though many may already have dropped or be dropping to the trees again. This dropping through the air, which is very rapid and is done with half-closed wings, may be witnessed any evening when the rooks return home from their day's work. My impression is that it is done for the sheer joy of the sensation, like their jubilant tumbling on windy days.

The raven has a remarkable air game of his own. When he is flying along leisurely, he will suddenly half close his wings and roll right over. The action is so rapid that the bird does not appear to drop while he is performing it, and at once he opens his wings again and continues his flight. This trick also forms part of the bird's nuptial display. So does the tumbling of the rook.

What happens in moulting is that the new feathers begin to grow and the old ones then drop out, but the changes are so gradual that it is only possible to study them thoroughly by means of a callous collection of skins. Some phases of the change, however, are obvious and full of interest to the ordinary observer. The wing and tail feathers drop one at a time on each side. That is to say, when a particular feather on one side drops, the same feather on the other side falls also, though, of course, not necessarily at the same moment. When these have been replaced, or when the new plumes have reached a certain stage in their growth, the next feather on each side drops and so on. The first of the principal wing feathers to go is the ninth counting from the tip, the next is the eighth, and the others in this order, the last being the outermost. When the wings are at full stretch, therefore, the gaps appear to begin with about the middle. In the tail, moulting starts with the central feathers, which are followed by the next on each side till the whole set has been renewed.

This moulting of the wings and tail is most noticeable on the rook. Every one has seen rooks passing overhead with feathers missing from their wings, and any one in a position to make daily observations of a rookery or of a particular flock of rooks, may watch the gradual progress of the change. The moulting of the rooks begins at a remarkably early date. This is obvious to every one for it is soon after May comes in that the birds appear with ragged wings. When we consider that this is the busiest period in the rook's life—for its family is growing fast and clamouring all day for food, which it must be constantly finding and fetching—it is astonishing to think that Nature should thus handicap the bird in its work. But the very fact that it has chicks to feed compels the rook to seek supplies as near as possible to the nest, and consequently the journeys though frequent are short, whereas later, when the young have flown and are able to take care of themselves, the feeding ground is usually some miles from the roosting place, and, moreover, the flock often takes to a nomad life, making long semi-migratory voyages in search of special food.

Again, the most outstanding feature of the rook is the patch of white skin at the base of the beak. by this we distinguish it in the field from the carrion crow, but before and after their first autumn moult the young show no sign of this mark. Even the adults, when after four months they have completed their new dress, have the chin fully clothed with black down, so when seen from below it is not easy to determine whether they are rooks or crows without hearing their calls. This down wears away quickly, however, and by January there is no trace of it. The young keep this part fully clothed with feathers throughout the winter, but moult those feathers during the spring. They are now, to a casual observer, exactly like their parents, but their coats are not nearly so glossy as those of the older birds, and they do not nest this season, for they are not full grown till after their second autumn moult. So in this species, there is a partial spring moult in the first year, and in subsequent years a small but distinct change is brought about by wear and tear.

Among the larger birds the rule is for each species to keep to itself. Even when several kinds may be feeding on the same ground, each quietly shakes itself free from the others when they are disturbed, and all go off in their separate bands. An exception to this is the frequent mixing of rooks and jackdaws, or rather of jackdaws with rooks.

Rooks, jackdaws and crows may be seen together on the same field or marsh. These birds are with us all the year round, but it is one thing to know them at their nesting places and quite another to recognise them in their winter quarters. According to the reference books the rook has a white patch of bare skin at the base of the beak and the crow has not, and the jackdaw is smaller than the other two and has grey on the back of his head and neck. Unfortunately these rules are not always enough to enable you to identify the birds in the open air. If you see a black bird that is large enough to be a member of the crow family and can be sure that it has the white bare skin at the base of the beak, you may be satisfied that it is a rook. But sometimes the light is deceptive, especially when the bird is at a distance, and causes you to think you see a white mark where there is none, and so you may believe a bird to be a rook though it is really a crow. Besides, not all rooks have the white patch, as I have shown in Chapter Eleven. So you may often see birds that seem to be crows though they are really rooks.

The rook's beak is straighter and more slender than the crow's. When he is on the ground some of the rook's feathers hang down round the upper part of his legs in such a way as to suggest that he is wearing knickerbockers or shorts. The crow's feathers all fit close to its body.

A readier means of distinguishing the two is that the rook flies and feeds in flocks and the crow singly or in pairs. But even this is not always to be depended upon; for often you may see a solitary rook flying overhead or sitting on a tree or searching for food, and it is not uncommon in autumn and winter for crows to live in parties.

The rook alights on the ground and walks about in a stately manner, picking up tit-bits here and there as he goes. His food consists of little things, such as worms, grubs and corn. But the crow is the carrion crow, and his favourite meal is the flesh of some dead animal, so he flies about in search of some such prize and alights when he finds it. Still, while he is in flight he may easily be mistaken for a rook, and the rook sometimes eats carrion.

Once you know the calls of the rook and the crow you need never confuse the two birds. Most people are unable to distinguish these calls because they are not in the habit of noticing the sounds they hear, and their attention has not been drawn to the difference. The rook's is a deep, hoarse ca-a-aw, and the crow's is a harsh car-r-r. The crow usually sounds his three times in quick succession, thus carr-carr-carr.

Unfortunately the carrion crow's call is the same as the hooded crow's. So when you hear it, though you need never mistake it for the call of the rook, you cannot be certain that it has been uttered by a carrion crow without actually seeing the bird. If you do see it and get a clear view of it, you will have no difficulty in deciding whether it is a hooded crow or not, for this bird has a slate grey body and black head, wings and tail.

Another species that may be mistaken for the carrion crow is the raven. This is a larger bird and has a much heavier bill. But at a distance you cannot depend on size as a guide, and in that case the only sure test is the call note. The raven's call is quite distinctive. It is a deep cr-r-ruck, which is uttered repeatedly. The raven lives in mountainous districts and on the coast, where there are inaccessible rocky cliffs on which it can roost and rear its family in security. It is in such districts only, therefore, that you are likely to confuse the raven with the crow. In other parts of the country the raven may be ruled out when you have any difficulty in identifying a member of the crow family.

Everywhere, however, the jackdaw is extremely common, and in flight he may be easily mistaken for either the crow or the rook. He is the smallest of the tribe, but, of course, at a distance the smallness of the jackdaw is no better guide than the largeness of the raven. His wingbeats are quicker than those of his larger cousins, and they are one of the signs by which you may know him when you are familiar with the bird and have been able to compare his flight frequently with that of the rook. At close quarters the jackdaw may be recognised by the grey patch on the back of his head. But his call is characteristic, and he will never keep you waiting long for that. He is constantly repeating his own name, Jack, as if he liked the sound of it. It is shorter and sharper than the call of the rook, and for comparison may best be represented by the syllable kya. But like most birds, the jackdaw has several calls, and one of them is not unlike the caw of the rook.

Jackdaws Nest Building
From plate pp111 by C.F. Tunnicliffe

There is one more black member of the crow tribe, the chough, but it is rare. The magpie and the jay also belong to this interesting family, but as each of them has a very striking plumage of its own, it is not possible to confuse them with any of their relatives. The magpie's black and white coat and his long black tail are unmistakable. His call is just as unmistakable, once you know it. It is a loud chattering cry, like chac-chac- chac-chac-chac-chack repeated rapidly. Naturally the magpie flocks in winter, and at one time parties numbering as many as twenty were to be seen in field and wood. Then the gamekeepers persecuted the species till it was reduced to isolated pairs. But during the Great War it was relieved from their attentions and was able to multiply. It is now fairly plentiful. I have myself had the pleasure of seeing six of these handsome birds on one thorn bush.

The jay is such a wary, shy bird that it is difficult to see him at close quarters. At the first sign of your approach, he flies off to a safe distance, uttering as he goes the harsh screaming note that has given him his name; it sounds like the tearing of a piece of cotton. It is seldom that you can get near enough to a jay to see the beautiful blue patch on his wings. But his reddish brown back with a large white patch on the rump and his black tail are conspicuous as he flies away from you. His manner of flight is also characteristic. It suggests that he is feeble, and when you see him crossing an open space you find yourself wondering whether he will be able to reach the farther side. This bird does not flock in summer, but it lives all the year round in colonies, and at pairing time the members of such communities hold some noisy meetings in the tree-tops



Flying Jay
From plate pp285 by C.F. Tunnicliffe

For generations the magpie and the jay have been persecuted by gamekeepers on the ground that they destroy the eggs and chicks of game. At one time flocks of magpies were not an uncommon sight in some parts of the country, but owing to the attentions of the gamekeeper, the species had, before the Great War, become comparatively scarce. Many specimens of both magpie and jay have recently been examined scientifically with the result that the magpie has been proved to be definitely beneficial and the jay neutral, or in other words, on the whole not injurious.

[snip] The rook and the starling have been convicted of taking sown grain in winter and spring. Both birds, however, go to the fields to feed on wire-worms, leather jackets and other injurious grubs that live in the ground, and the good they do by destroying these pests far outweighs any damage they may cause incidentally. If the farmer had to pay for the destruction of the grubs, the cost would be greater than the value of the grain he loses and the work very badly done. A farmer recently wrote to the newspapers that when he bought his farm he could grow no corn because, owing to the persecution of the rooks by his predecessor, the fields had become infested with wire-worms. He had at once reversed this policy by encouraging the rook and had induced it to establish a rookery on his land, with the result that the pest had been controlled and the fields were now yielding good crops.