WITH the single exception of the nightingale, bird of lovers, no other has been more written of in prose or verse than the so-called "harbinger of spring." This is a foolish name for a visitor that does not reach our shores before, at any rate, the middle of April. Even Whitaker allows us to recognise the coming of spring nearly a month earlier; and for myself, impatient if only for the illusion of Nature's awakening, I date my spring from the ending of the shortest day. Once the days begin to lengthen, it is time to glance at the elms for the return of the rooks and to get out one's fishing-tackle again. Yet the cuckoo comes rarely before the third week of April, save in the fervent imagination of premature heralds, who, giving rein to a fancy winged by desire, or honestly deceived by some village cuckoo clock heard on their country rambles, solemnly write to the papers announcing the inevitable March cuckoo. They know better in the Channel Islands, for in the second week[56] of April, and not before, there are cuckoos in every bush—hundreds of exhausted travellers pausing for strength to complete the rest of their journey to Britain. Not on the return migration in August do the wanderers assemble in the islands, since, having but lately set out, they are not yet weary enough to need the rest. The only district of England in which I have heard of similar gatherings of cuckoos is East Anglia, where, about the time of their arrival, they regularly collect in the bushes and indulge in preliminary gambols before flying north and west.  
Cuckoos, then, reach these islands about the third week of April, and they leave us again at the end of the summer, the old birds flying south in July, the younger generation following three or four weeks later. Goodness knows by what extraordinary instinct these young ones know the way. But the young cuckoo is a marvel altogether in the manner of its education, since, when one comes to think of it, it has no upbringing by its own parents and cannot even learn how to cry "Cuckoo!" by example or instruction. Its foster-parents speak another language, and[57] its own folk have ceased from singing by the time it is out of the nest. A good deal has been written about the way in which the note varies, chiefly in the direction of greater harshness and a more staccato and less sustained note, towards the end of the cuckoo's stay. According to the rustic rhyme, it changes its tune in June, which is probably poetic licence rather than the fruits of actual observation. It is, however, commonly agreed that the cuckoo is less often heard as the time of its departure draws near, and the easiest explanation of its silence, once the breeding season is ended, is that the note, being the love-call of a polygamous bird, is no longer needed.
 
In Australia the female cuckoo is handsomely barred with white, whereas the male is uniformly black; but with our bird it is exceedingly difficult to distinguish one sex from the other on the wing, and, were it not for occasional evidence of females having been shot when actually calling, we might still believe that it is the male only that makes this sound. The note is joyous only in the poet's fancy, just as he has also read sadness[58] into the "sobbing" of the nightingale. There is, indeed, when we consider its life, something fantastic in the hypothesis that the cuckoo can know no trouble in life, merely because it escapes the rigours of our winter. Eternal summer must be a delight, but the cuckoo has to work hard for the privilege, and it must at times be harried to the verge of desperation by the small birds that continually mob it in broad daylight. This behaviour on the part of its pertinacious little neighbours has been the occasion of much futile speculation; but the one certain result of such persecution is to make the cuckoo, along with its fellow-sufferer, the owls, preferably active in the sweet peace of the gloaming, when its puny tyrants are gone to roost. Much heated argument has raged round the real or supposed sentiment that inspires such demonstrations on the part of linnets, sparrows, chaffinches, and other determined hunters of the cuckoo. It seems impossible, when we observe the larger bird's unmistakable desire to win free of them, to attribute friendly feelings to its pursuers. Yet some writers have held the[59] curious belief that, with lingering memories of the days when, a year ago, they devoted themselves to the ugly foster-child, the little birds still regard the stranger with affection. If so, then they have an eccentric way of showing it, and the cuckoo, driven by the chattering little termagants from pillar to post, may well pray to be saved from its friends. On the other hand, even though convinced of their hostility, it is not easy to believe, as some folks tell us, that they mistake the cuckoo for a hawk. Even the human eye, though slower to take note of such differences, can distinguish between the two, and the cuckoo's note would still further undeceive them. The most satisfactory explanation of all perhaps is that the nest memories do in truth survive, not, however, investing the cuckoo with a halo of romance, but rather branding it as an object of suspicion, an interloper, to be driven out of the neighbourhood at all costs ere it has time to billet its offspring on the hard-working residents. All of which is, needless to say, the merest guesswork, since any attempt to interpret the simplest actions of birds is likely to lead us[60] into erroneous conclusions. Yet, of the two, it certainly seems more reasonable to regard the smaller birds as resenting the parasitic habit in the cuckoo than to admit that they can actually welcome the murder of their own offspring to make room in the nest for the ugly changeling foisted on them by this fly-by-night.
 
On the lucus a non lucendo principle, the cuckoo is chiefly interesting as a parent. The bare fact is that our British kind builds no nest of its own, but puts its eggs out to hatch, choosing for the purpose the nests of numerous small birds which it knows to be suitable. Further investigation of the habits of this not very secretive bird, shows that she first lays her egg on the ground and then carries it in her bill to a neighbouring nest. Whether she first chooses the nest and then lays the egg destined to be hatched in it, or whether she lays each egg when so moved and then hunts about for a home for it, has never been ascertained. The former method seems the more practical of the two. On the other hand, little nests of the right sort are so plentiful in May that, with her mother-instinct to guide[61] her, she could always find one at a few moments' notice. Some people, who are never so happy as when making the wonders of Nature seem still more wonderful than they really are, have declared that the cuckoo lays eggs to match those among which she deposits them, or that, at any rate, she chooses the nests of birds whose eggs approximately resemble her own. I should have liked to believe this, but am unfortunately debarred by the memory of about forty cuckoo's eggs that I took, seven-and-twenty summers ago, in the woods round Dartford Heath. The majority of these were found in hedgesparrows' nests, and the absolute dissimilarity between the great spotted egg of the cuckoo and the little blue egg of its so-called dupe would have impressed even a colour-blind animal. Occasionally, I believe, a blue cuckoo's egg has been found, but such a freak could hardly be the result of design. As a matter of fact, there is no need for any such elaborate deception. Up to the moment of hatching, the little foster-parents have in all probability no suspicion of the trick that has been played on them. Birds do not take[62] deliberate notice of the size or colour of their own eggs. Kearton somewhere relates how he once induced a blackbird to sit on the eggs of a thrush, and a lapwing on those of a redshank. So, too, farmyard hens will hatch the eggs of ducks or game birds and wild birds can even be persuaded to sit on eggs made of painted wood. Why then, since they are so careless of appearances, should the cuckoo go to all manner of trouble to match the eggs of hedgesparrow, robin or warbler? The bird would not notice the difference, and, even if she did, she would probably sit quite as close, if only for the sake of the other eggs of her own laying. Once the ugly nestling is hatched, there comes swift awakening. Yet there is no thought of reprisal or desertion. It looks rather as if the little foster-parents are hypnotised by the uncouth guest, for they see their own young ones elbowed out of the home and continue, with unflagging devotion, to minister to the insatiable appetite of the greedy little murderer. A bird so imbued as the parasitic cuckoo with the Wanderlust would make a very careless parent, and we must therefore perhaps revise our unflattering[63] estimate of its attitude and admit that it does the best it can by its offspring in putting them out to nurse. This habit, unique among British birds, is practised by many others elsewhere, and in particular by the American troupials, or cattle-starlings. One of these indeed goes even farther, since it entrusts its eggs to the care of a nest-building cousin. There are also American cuckoos that build their own nest and incubate their own eggs.
 
On the whole, our cuckoo is a friend to the farmer, for it destroys vast quantities of hairy caterpillars that no other bird, resident or migratory, would touch. On the other hand, no doubt, the numbers of other small useful birds must suffer, not alone because the cuckoo sucks their eggs, but also because, as has been shown, the rearing of every young cuckoo means the destruction of the legitimate occupants of the nest. So far however as the farmer is concerned, this is probably balanced by the reflection that a single young cuckoo is so rapacious as to need all the insect food available.
 
The cuckoo, like the woodcock, is supposed to have its forerunner. Just as the small[64] horned owl, which reaches our shores a little in advance of the latter, is popularly known as the "woodcock owl," so also the wryneck, which comes to us about the same time as the first of the cuckoos, goes by the name of "cuckoo-leader." It is never a very conspicuous bird, and appears to be rarer nowadays than formerly. Schoolboys know it best from its habit of hissing like a snake and giving them a rare fright when they cautiously insert a predatory hand in some hollow tree in search of a possible nest. It is in such situations that, along with titmice and some other birds, the wryneck rears its young; and it doubtless owes many an escape to this habit of hissing, accompanied by a vigorous twisting of its neck and the infliction of a sufficient peck, easily mistaken in a moment of panic for the bite of an angry adder. Thus does Nature protect her weaklings.