Some Goatsuckers have certain feathers of their wings so remarkably developed, that they have been called by the Arabs "the four-winged birds," and are described by Swainson under the name of MACRODIPTERYX.
THE LONG-WINGED MACRODIPTERYX.
The LONG-WINGED MACRODIPTERYX (Macrodipteryx longipennis) has the tail of moderate size, and straight at its extremity; the foot resembles that of the European species; the beak is delicate and furnished with long bristles at its base. The plumage of the male bird is characterised by the long appendages which grow between the primary and secondary quills. These appendages, or rather shafts, are frequently seventeen inches long, entirely bare to within six inches of the extremity, where the web grows upon both sides and forms a broad expansion. The wing of the female is entirely without this remarkable structure. The plumage, which is somewhat dusky, is a mixture of red and black; the throat is paler, and the nape decorated with a yellowish tint; the primaries are striped black and red, with a dark tip; the secondaries are black with four red stripes. The centre tail-feathers are grey, spotted and streaked with black. The length of these birds is about five inches: the tail measures from three and a half to four, and the wing six inches and three-quarters.
THE STREAMER-BEARING NIGHT JAR OR "FOUR WINGS."
The STREAMER-BEARING NIGHT JAR, or "FOUR WINGS" (Cosmetornis vexillarius), is another remarkable species, closely allied to that above described, but distinguished by the development, not of one only, but of two excessively long feathers, that grow from each wing. These peculiar appendages are furnished with a web upon both sides, extending throughout their entire length. We are entirely without particulars as to the life and habits of this extremely rare bird, which inhabits South-eastern Africa.
All the various groups of Goatsuckers whose outward appearance we have thus briefly described frequent woodland districts or forests, in the immediate neighbourhood of large plains and open fields, as such localities abound with the insects on which they mainly rely for nourishment. Still there are exceptions. The Red-throated Goatsucker, for example, is most frequently seen upon rocks slightly overgrown with trees or shrubs, and though it builds in various situations, prefers plantations of olive-trees, when about to make its nest, whilst the Cream-coloured Night Jar (Caprimulgus isabellinus), on the contrary, usually conceals itself amidst the bushes or grass that cover the sandy banks of the Nile. During the day most species seek a shady retreat, and either sit upon the ground whilst reposing, or find shelter upon trees, on the boughs of which they recline, not after the manner of other birds, but in such a position as to allow the entire body to lie along the supporting branch, holding themselves, meanwhile, firmly in place by means of their inner toes, and the serrated claw, with which the central toe is furnished; it is only when disturbed from their slumbers that the Goatsuckers perch in the ordinary manner; as soon as the supposed danger is over, they at once resume their favourite attitude. Whilst asleep the eyelids are kept completely closed, but if suddenly awakened, these birds blink, and peer around them, after the fashion of an Owl, and seek to conceal themselves by lying close to the earth, or to the tree on which they are reposing. Upon the ground they move with much difficulty; indeed, it has often been stated that their feet are useless as a means of progression, but this is not the case, as we have on several occasions seen the African Goatsuckers walk some little distance when passing from one resting-place to another. The flight of all these various groups is unsteady and apparently aimless during the day, but at sunset they seem endowed with new life, and may be seen alternately skimming and hovering over the face of the country, in pursuit of moths, beetles, and various other insects, upon which they subsist. When their appetite is appeased, they rest for a time upon some branch, and then sally forth again before morning dawns to procure a second repast. It is not uncommon for the Goatsuckers to wander to a very considerable distance from their usual haunts during these nocturnal excursions, and even approach the immediate vicinity of towns and villages; nay, so inquisitive and bold are they in regard to the objects they meet with whilst in search of prey, that they will often follow and hover round a man or a dog for a quarter of an hour at a time. During the breeding season their flight becomes still more varied and beautiful, and the birds themselves seem roused to a higher degree of intelligence than is observable at other times; such species especially, as possess the remarkably long wings or tails we have described, cannot fail to impress those who are fortunate enough to see them gliding or hovering aloft, with their flowing plumage alternately closed or outspread, as they perform their light and elegant gyrations through the realms of air. Russegger describes the African "Four Wings" as looking like some strange being from another world, as it whirls along, at one moment appearing to multiply itself by rapidly assuming the most various attitudes, or revolving like a shuttlecock, with its long feathers streaming and twisting in the wind. The voices of these various birds differ very considerably; some species uttering a harsh, droning note, not unlike the sound of a spinning-wheel (whence is derived their name of "Night Jar," or "Night Churr"), whilst others are capable of producing by no means inharmonious tones. The European Goatsucker, when alarmed, purrs very much like a cat, and during the breeding season attracts the attention of its mate by two distinct notes; at other times its cry may be represented by the syllables, "Dak, dak," faintly and hoarsely uttered. So dismal and unearthly are the voices of some American Night Jars, that Schomburghk tell us that neither Indians, Creoles, nor Negroes would venture to shoot one of them, regarding them as direct embodiments of, or emissaries from, the various evil spirits and enchanters, of whose machinations and spells the ignorant natives live in constant dread.
"A Goatsucker," says Waterton, "inhabits Demerara, about the size of an English Wood Owl, whose voice is so remarkable that when once heard it is not to be easily forgotten. A stranger would never believe it to be the cry of a bird, but would say it was the departing voice of a midnight murdered victim, or the last wailing of poor Niobe for her children, before she was turned to stone. Suppose a person in hopeless sorrow, beginning with a loud note, 'Ha, ha; ha, ha; ha, ha, ha;' each note lower and lower, till the last is scarcely heard, pausing a moment between each exclamation, and you will have some idea of the moaning of the Great Goatsucker of Demerara. Other species articulate some words so distinctly that they have received their names from the sentences they utter, and absolutely bewilder a stranger on his arrival in their vicinity. One sits down close to your door, or flies and alights three or four yards before you as you walk along the road, crying, 'Who are you? who, who are you?' Another bids you 'Work away; work, work, work away!' A third cries mournfully, 'Willy, come go; Willy, Willy, Willy, come go!' and a fourth tells him to 'Whip-poor-Will, Whip-poor-Will!' in tones wonderfully clear and startling."
As regards their instincts and capabilities, the nocturnal Goatsuckers are far behind the diurnal members of their family, and exhibit so little sense of self-preservation, as constantly to expose themselves to great danger. We have frequently, whilst camping out in Africa, whenever we have kindled a fire, been visited by numbers of these birds, apparently quite regardless of the risk they ran of being brought down by our gun. In Spain, however, the Goatsuckers appear to be somewhat more on the alert; indeed, owing to their supposed dexterity in evading pursuit, they are there called by the peasantry Engaña Pastor, or "Shepherd Deceivers," as that class of men come most in contact with these birds, whilst tending their flocks; not from the absurd reason that has obtained such universal credence, but because these much-maligned visitants perform a most invaluable service both to the farmer and his cattle.