THE majority of nocturnal animals, more particularly those bent on spoliation, are strangely silent. True, frogs croak in the marshes, bats shrill overhead at so high a pitch that some folks cannot hear them, and owls hoot from their ruins in a fashion that some vote melodious and romantic, while others associate the sound rather with midnight crime and dislike it accordingly. The badger, on the other hand, with the otter and fox—all of them sad thieves from our point of view—have learnt, whatever their primeval habits, to go about their marauding in stealthy silence; and it is only in less settled regions that one hears the jackals barking, the hy?nas howling, and the browsing deer whistling through the night watches.  
There are, however, two of our native birds, or rather summer visitors, since they leave us in autumn, closely associated with these warm June nights, the stillness of which they break in very different fashion, and these are the nightingale and nightjar. Each is of considerable[68] interest in its own way. It is not to be denied that the churring note of the nightjar is, to ordinary ears, the reverse of attractive, and the bird is not much more pleasing to the eye than to the ear; while the nightingale, on the contrary, produces such sweet sounds as made Izaak Walton marvel what music God could provide for His saints in heaven when He gave such as this to sinners on earth. The suggestion was not wholly his own, since the father of angling borrowed it from a French writer; but he vastly improved on the original, and the passage will long live in the hearts of thousands who care not a jot for his instructions in respect of worms. At the same time, the nightjar, though the less attractive bird of the two, is fully as interesting as its comrade of the summer darkness, and there should be no difficulty in indicating the little that they have in common, as well as much wherein they differ, in both habits and appearance.
 
Both, then, are birds of sober attire. Indeed of the two, the nightjar, with its soft and delicately pencilled plumage and the conspicuous white spots, is perhaps the handsomer,[69] though, as it is seen only in the gloaming, its quiet beauty is but little appreciated. The unobtrusive dress of the nightingale, on the other hand, is familiar in districts in which the bird abounds, and is commonly quoted, by contrast with its unrivalled voice, as the converse of the gaudy colouring of raucous macaws and parrakeets. As has been said, both these birds are summer migrants, the nightingale arriving on our shores about the middle of April, the nightjar perhaps a fortnight later. Thenceforth, however, their programmes are wholly divergent, for, whereas the nightjars proceed to scatter over the length and breadth of Britain, penetrating even to Ireland in the west and as far north as the Hebrides, the nightingale stops far short of these extremes and leaves whole counties of England, as well as probably the whole of Scotland, and certainly the whole of Ireland, out of its calculations. It is however well known that its range is slowly but surely extending towards the west.
 
This curiously restricted distribution of the nightingale, indeed, within the limits of its summer home is among the most remarkable[70] of the many problems confronting the student of distribution, and successive ingenious but unconvincing attempts to explain its seeming eccentricity, or at any rate caprice, in the choice of its nesting range only make the confusion worse. Briefly, in spite of a number of doubtful and even suspicious reports of the bird's occurrence outside of these boundaries, it is generally agreed by the soundest observers that its travels do not extend much north of the city of York, or much west of a line drawn through Exeter and Birmingham. By way of complicating the argument, we know, on good authority, that the nightingale's range is equally peculiar elsewhere; and that, whereas it likewise shuns the departments in the extreme west of France, it occurs all over the Peninsula, a region extending considerably farther into the sunset than either Brittany or Cornwall, in both of which it is unknown. No satisfactory explanation of the little visitor's objection to Wild Wales or Cornwall has been found, and it may at once be stated that its capricious distribution cannot be accounted for by any known facts of soil,[71] climate, or vegetation, since the surroundings which it finds suitable in Kent and Sussex are equally to be found down in the West Country, but fail to attract their share of nightingales.
 
The song of the nightingale, in praise of which volumes have been written, is perhaps more beautiful than that of any other bird, though I have heard wonderful efforts from the mocking-bird in the United States and from the bulbuls along the banks of the Jordan. The latter are sometimes, more especially in poetry, regarded as identical with the nightingale; and, indeed, some ornithologists hold the two to be closely related. What a gap there is between the sobbing cadences of the nightingale and the rasping note of the nightjar, which, with specific reference to a Colonial cousin of that bird Tasmanians ingeniously render as "more pork"! It seems almost ludicrous to include under the head of birdsong not only the music of the nightingale, but also the croak of the raven and the booming note of the ostrich. Yet these also are the love-songs of their kind, and the hen ostrich doubtless[72] finds more music in the thunderous note of her lord than in the faint melody of such song-birds as her native Africa provides. The nightingale sings to his mate while she is sitting on her olive-green eggs perching on a low branch of the tree, at foot of which the slender nest is hidden in the undergrowth. So much is known to every schoolboy who is too often guided by the sound on his errand of plunder; and why the song of this particular warbler should have been described by so many writers as one of sadness, seeing that it is associated with the most joyous days in the bird's year, passes comprehension. So obviously is its object to hearten the female in her long and patient vigil that as soon as the young are hatched the male's voice breaks like that of other choristers to a guttural croak. It is said, indeed—though so cruel an experiment would not appeal to many—that if the nest be destroyed just as the young are hatched the bird recovers all his sweetness of voice and sings anew while another home is built.
 
Although poetic licence has ascribed the song to the female, it is the male nightingale[73] only that sings, and for the purpose aforementioned. The note of the nightjar, on the other hand, is equally uttered by both sexes, and both also have the curious habit of repeatedly clapping the wings for several minutes together. They moreover share the business of incubation, taking day and night duty on the eggs, which, two in number, are laid on the bare ground without any pretence of a nest, and generally on open commons in the neighbourhood of patches of fern-brake. Like the owls, these birds sleep during the day and are active only when the sun goes down. It is this habit of seeking their insect food only in the gloaming which makes nightjars among the most difficult of birds to study from life, and all accounts of their feeding habits must therefore be received with caution, particularly that which compares the bristles on the mouth with baleen in whales, serving as a sort of strainer for the capture of minute flying prey. This is an interesting suggestion, and may even be sober fact; but its adoption would necessitate the bird flying open-mouthed among the oaks and other trees beneath which it finds[74] the yellow underwings and cockchafers on which it feeds, and I have more than once watched it hunting its victims with the beak closed. I noticed this particularly when camping in the backwoods of Eastern Canada where the bird goes by the name of nighthawk.
 
In all probability its food consists exclusively of insects, though exceptional cases have been noted in which the young birds had evidently been fed on seeds. The popular error which charges it with stealing the milk of ewes and goats, from which it derives the undeserved name of "goat-sucker," with its equivalent in several Continental languages, is another result of the imperfect light in which it is commonly observed. Needless to say, there is no truth whatever in the accusation, for the nightjar would find no more pleasure in drinking milk than we should in eating moths.
 
Here, then, are two night-voices of very different calibre. These are not our only birds that break the silence on moonlight nights in June. The common thrush often sings far into the night, and the sedge-warbler is a[75] persistent caroller that has often been mistaken for the nightingale. The difference in this respect between the two subjects of these remarks is that the nightjar is invariably silent all through the day, whereas the nightingale sings joyously at all hours. It is only because his splendid music is more marked in the comparative silence of the night, with little or no competition, that his daylight concert is often overlooked.