Fig. 87.–Nightjar or Goatsucker. Caprimulgus europaeus. × ⅓.
Sub-fam. 2. Nyctibiinae.–Six species of Nyctibius occur in Tropical America, including Jamaica, and utter wailing cries.
Fam. IX. Podargidae.–This group includes some five and twenty members of the genera Podargus, Batrachostomus[[239]] (Frog-mouth), and Aegotheles. The first and last occupy Papuasia, Tasmania, and Australia, the second ranges from the Himalayas to Ceylon, the Philippines, and Malay Islands.
Fam. X. Steatornithidae.–This contains only the curious Guácharo, or Oil-bird (Steatornis caripensis) discovered in 1799 by Humboldt and Bonpland at Caripé in Venezuela, but now known to breed also in Colombia, Ecuador, and Peru, as well as in Guiana and Trinidad. Somewhat intermediate between the Owls and the Nightjars, this species is about the size of a Crow, with a similar hard beak, hooked and deeply notched, while it has twelve long stiff bristles on each side of the gape. The tibiae and metatarsi are covered with smooth, flesh-coloured skin, the toes being deeply cleft, and not basally united. The tongue is thin and triangular, the nostrils have a horny covering, the after-shaft is fairly large, while the rest of the structure is mainly Caprimulgine. The acuminate and not particularly soft feathers are chocolate and grey, with darker barring above, and shew white spots, often surrounded by black, in various parts. This bird inhabits sea-side or mountain-caverns, only issuing forth at dusk to traverse considerable distances in search of its food, which consists mainly, if not wholly, of fruits. The flight is noiseless, and occasionally high in the air. Visitors to the breeding caves are suddenly surrounded by a circling crowd of Oil-birds uttering loud croaking or rasping cries, the effect being enhanced by the rush of multitudinous wings. A more plaintive note is uttered by individuals at rest. The numerous nests, each containing from two to four white or dirt-begrimed eggs, are flat circular masses of a clay-like substance, placed on ledges or in holes; while the nestlings are considered a table delicacy, though said to be scented like cockroaches. The natives systematically kill large numbers at certain seasons by knocking them down with poles when scared by torchlight, and melt out the abundant fat to procure the oil, which gives the bird its name. This oil is used for illumination or cooking, and keeps admirably.
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The Sub-Order Cypseli consists of the Families Cypselidae or Swifts, and Trochilidae or Humming-birds,[[240]] which were first grouped together by Nitzsch as Macrochires (long-handed forms) from the length of their manual bones, though really the parts of the wing nearer the body are proportionally most elongated.
Swifts certainly differ from Humming-birds in the broad, flat skull, the short curved bill, and the extremely wide gape, besides their comparatively sombre coloration; but these facts cannot be allowed to militate against an alliance so strongly confirmed by many points of structure, while nothing but the pardonable ignorance of former times caused the Family to be united with their Passerine analogues, the Swallows. The Cypselidae agree with the Trochilidae in the number and colour of their eggs, and the extraordinarily deep keel of the sternum, which, with the long wings, gives so great a power of flight.
Fam. XI. Cypselidae.–Of this group three Sub-families may be recognised, (1) Macropteryginae, (2) Chaeturinae, and (3) Cypselinae.
The short but robust metatarsi are scutellated anteriorly, the scales being nearly obsolete in the Chaeturinae; fairly powerful claws terminate the free toes, which are all directed forwards in the Cypselinae, though the hallux is somewhat laterally inclined in Panyptila, and is said to be occasionally versatile in the other Sub-families. The middle and outer digits in the Cypselinae have the further peculiarity of possessing only three joints, while the metatarsi or even the toes are feathered. The ten primaries, and especially the exterior, are extremely long, with thick narrow outer webs; the short secondaries vary from six to eight. The square or forked tail has ten rectrices–not uncommonly rigid and pointed–as against twelve in Swallows. The furcula is U-shaped; the tongue sagittate; the syrinx tracheo-bronchial (the muscles not being inserted on the bronchial rings); the aftershaft is large or small; the adults have a little blackish down on the unfeathered spaces; the nestlings are blind and naked.