Of fossil forms there are recorded Gyps melitensis[[130]] from the Plistocene of Malta, and Vultur from that of France.[[131]]
Fam. IV. Falconidae.–This group may be divided into the Sub-families (1) Gypaëtinae for the Lämmergeiers; (2) Polyborinae for the "Carrion Hawks"; (3) Accipitrinae for the Hawks, with Circus, Polyboroïdes, and so forth; (4) Aquilinae for the Eagles; (5) Buteoninae for the Buzzards and Kites; and (6) Falconinae for the Falcons.
Though the skull is small in Circus and some other forms, it is usually large and broad, being considerably elongated in the Aquilinae. The short stout bill is strongly curved, and terminates in a hook, which is often nearly perpendicular, and is specially prominent in Rostrhamus, Leptodon, Harpyhaliaëtus, Pithecophaga and Thrasaëtus; the basal third is straight in Eagles, while the edges of the maxilla are lobed or festooned to a variable extent, and in the Falconinae are distinctly toothed, or even bidentate in the case of Spiziapteryx, Harpagus, and Baza. A bony ridge over the eye conduces to the fierce aspect, especially in the larger species. The feet are robust and well-fitted for grasping, and are enormously developed in Thrasaëtus; the metatarsus is much flattened, and may be scutellated or reticulated, though the scales are usually smaller behind; the tibia generally exceeds it in measurement, but in Accipitrine forms is nearly equal, giving them a long-legged appearance. Elongated bare metatarsi are characteristic of Circus, Polyboroïdes, and the Polyborinae. The claws are sharp and curved, especially in Rostrhamus; a short membrane connects the middle and outer toes, and the inner also in the Polyborinae; while their under surface is more or less padded, and exhibits rugose spicules below in Busarellus, similar to those in Pandion. The powerful wings may be long and pointed, as in the Kites, Falcons, and Harriers; moderate and somewhat rounded, as in the Eagles and Buzzards; or short and narrow, as in Hawks. Falconers term the long-winged forms "noble," the short-winged ignoble. The tail, usually of medium size, but sometimes very short, as in Helotarsus and Gypohierax, is decidedly elongated in the Accipitrinae and Polyborus, and also in Milvus, Lophoictinia, Elanoïdes, and Nauclerus, where it is forked–very deeply in the two last: it may be wedge-shaped, as in Uroaëtus, Thalassaëtus, Harpyhaliaëtus, and Gypaëtus; rounded, as in Elanus and Haliaëtus; nearly even, as in Buteo and Aquila; or emarginated, as in Ictinia and Rostrhamus. Normally there are twelve rectrices, but Thalassaëtus has fourteen. The colour varies greatly with age, and it often takes four years or more to attain maturity, the markings commonly changing from longitudinal to transverse; but the sexes are usually alike, though the Kestrel, Merlin, Red-footed Falcon, and many Harriers are well-known exceptions, the last having generally blue-grey males and brown females. The occipital feathers are elongated in several of the Polyborinae, and a full crest occurs in many genera, Lophoaëtus, Thrasaëtus, Harpyhaliaëtus, Helotarsus, Morphnus, and Lophoictinia being especially noticeable; Circus has a facial ruff, coupled with exceptionally large aural apertures; the feathers of the neck may be lanceolate, as in Haliaëtus, or those of the nape, as in Aquila; and the plumage commonly over-hangs the metatarsus, which is feathered to the toes in various Aquiline forms, and in Archibuteo. The nostrils are circular in the Falconinae, oval or nearly linear elsewhere, with a central tubercle in the last-named and the Polyborinae, seldom found in the other Sub-families: they are generally in or near the cere, which is almost always fleshy. An aftershaft is present; the down in adults is uniform; that of the nestling being woolly and varying from white to grey, buff, brown, or black. The feet are yellow, red, or brown; the bill is ordinarily dark, and the cere yellow; Gypaëtus, however, has all these parts bluish-grey, with a crimson sclerotic membrane (equivalent to the "white of the eye") round the orange iris, the latter being yellow or orange in the Accipitrinae, brown in the Falconinae, and varying to red elsewhere. The syrinx has two pairs of tracheo-bronchial muscles; the tongue is thick and often concave; and Nitzsch[[132]] has recorded single or paired powder-down patches on the lower back of Elanoïdes, Elanus, Regerhinus, and Circus, with similar but scattered down-feathers in Gypaëtus.
The members of this Family range in size from the mighty Lämmergeier to the tiny Finch-Falcon (Microhierax); but they have many habits in common, though Polyborus and Milvago are somewhat terrestrial and vulturine, and a few species have crepuscular tendencies. They are decidedly non-gregarious, though the Polyborinae, Erythropus, and Rostrhamus form partial exceptions; they pair very early in the year, if not for life, the larger forms in especial breeding almost before winter is over. Birds of the mountains, the plains, and the woods, they can bear the cold of the icy regions or the heat of the Equator, but towards either pole the number of species decreases perceptibly. The sight is exceptionally keen, and the flight generally powerful and rapid; Eagles and Buzzards indeed move heavily to all appearance, as they circle or sail around with flapping action, but the spectacle of the former in chase of a grouse will quickly disillusion the observer. Kites are still more versatile upon the wing, nor are the Polyborine forms always deficient in this respect, while the dash and speed of Hawks and Falcons in their different styles is proverbial.[[133]] Harriers and the like may be seen buoyantly quartering the ground for hours, poising themselves almost motionless aloft, or gliding in circles to great heights; and the hovering or stationary position on the wing, which gives the name of "Windhover" to the Kestrel, is more general than might be supposed throughout the Family. Taken as a class, few birds can fly so well or so untiringly, though Vultures, Cranes, Storks, Albatroses, and the larger Gulls have even greater powers of endurance; they can, moreover, perch with great facility, and, while seldom running or walking fast, can move with freedom upon the ground, where they generally progress by means of hops, and aid themselves with their wings. Many of the Falconidae are very quarrelsome, and use their talons as weapons of offence, this trait being emphasized at the nesting-quarters, whence feathered intruders are rigorously excluded. The cry is shrill, but varies in depth; in the Peregrine Falcon it is a succession of short notes, in Eagles it resembles a yelp, in Buzzards a cat's mew, in Kites a whistle, and so forth; whereas in Melierax it may almost be called a song. The diet varies considerably, and consists of mammals, birds, reptiles, fish, frogs, tortoises, crabs, molluscs, and insects. Gypohierax, Aquila, Haliastur, Milvago, and Polyborus certainly eat carrion, and the last will attack newly-born lambs–a grievance made the most of by sheep-farmers in the case of Eagles; while the larger forms kill fawns, monkeys, foxes, hares, and other creatures of considerable size. Buzzards keep down rabbits, and hunt rats and mice as assiduously as Harriers and the Kestrel; the latter devours quantities of insects, as do also some of the Polyborinae; and the so-called "Honey" Buzzard (Pernis) gains its name from its fondness for grubs of bees or wasps. Kites work havoc among poultry; the Golden Eagle, and still more the Peregrine Falcon, among moor-fowl; the last two proving an advantage in Scotch deer-forests, where the noisy grouse disturb the stags, but being in peril of extermination on the moorlands; yet it is questionable whether more good than harm is not done by the destruction of weakly game. The Osprey and Sea-Eagle eat little but fish, though they are not alone in that habit, while Rostrhamus lives almost entirely on fresh-water molluscs. Most members of the Family do not alight to capture their prey, but seize it with their sharp talons either sitting or on the wing, the chief exceptions being the carrion- and insect-eaters; it is often conveyed to some favourite spot of ground or rock to devour, smaller objects being transported in the bill and the bigger torn to pieces and stripped before being swallowed. Large bones may be broken up, slender bones bolted entire; but hard substances are always ejected subsequently as pellets, after the manner of Owls (p. [401]), the nature of the diet being readily detected from these castings. Exceptionally curious habits are credited to Gypaëtus and Gypoictinia, as will be seen below. After a meal, quiescence is the rule, but none of the tribe gorge like Vultures. The predilections of species or even of individuals determine the situation of the nest, Eagles and other large forms preferring rocks in mountain-glens, lofty cliffs, or trees, for their bulky fabric of sticks, heather, and the like, which is lined with softer substances, and often bedded with foliage. The larger Falcons frequently select ledges on sea-girt or inland crags, and merely scrape a hole in the soil; but they, in common with the lesser Falcons, also utilize deserted habitations of Crows and so forth, or even lay their eggs on level ground or upon crumbling masonry; while the American "Sparrow-Hawk" (Tinnunculus sparverius) commonly appropriates old holes of Woodpeckers. Harriers, Rostrhamus, and other forms choose sites in reed-beds, gorse-coverts, fern, rough grass, or corn, and eschew hard materials; Hawks usually construct a flat platform of branches lined with thinner twigs. The eggs are generally bluish-, greenish-, or yellowish-white, with fine blotches, streaks, and spots of red, brown, or claret, chiefly towards the larger end; but in Falcons they are more or less covered with ruddy or orange markings, which often obliterate the ground-colour. Unspotted specimens are not uncommon, and in the case of Harriers we have an instance of a plain bluish coloration, a few rusty stains being exceptionally visible. Alternative sites are frequently tenanted, or former nests repaired. Incubation is often of considerable duration, and the young remain long in the nest–four months, it is said, in the Lämmergeier; the longevity, too, of Eagles is notorious, a span of a hundred years having been actually recorded. Unconscious mimicry is shewn by Accipiter pileatus, which assumes the garb of Harpagus diodon near Rio Janeiro.
Fig. 39.–Lämmergeier. Gypaëtus barbatus. × ⅛-⅑.
Sub-fam. 1. Gypaëtinae.–This group apparently links the Vulturidae to the Falconidae, but seems nearer to the latter. Gypaëtus barbatus, the magnificent Lämmergeier, is greyish-black with white streaks, and has a white crown, cheeks with a black band bifurcating at the eye to meet above, and pale tawny lanceolate plumage on the neck and lower parts. Dense black bristles cover the nostrils and lores, and a black tuft, which gives the name of Bearded Vulture, projects below the mandible. The sclerotic membrane is crimson (p. [147]). The young are chiefly brown and buff. From Portugal and Mauritania this species extends through the lofty mountains of South Europe to the Himalayas and North China, though practically exterminated in Switzerland and Carinthia; G. ossifragus (meridionalis), with no black stripe below the eye, represents it in North-Eastern and Southern Africa. Avoiding its own kin, the Lämmergeier often breeds near Griffon Vultures; the large nest of sticks, lined with wool and hair, begun very early in the year, being placed in some cavity of a cliff or on a precipitous ledge, and containing one egg–or rarely two–which appear pale orange owing to the confluent markings. The flight is majestic and powerful; the cry weak and querulous, with a croak when irritated. In parts of Spain and India, natives assert that this bird preys only on carcases; but in Macedonia it is said to carry off lambs, kids, and fowls, and no doubt occasionally it kills small mammals and birds, though all statements should be carefully criticised, as it usurps the name of "Grifo" or Griffon in Spain, and that of Golden Eagle in India; while conversely any Eagle is pointed out in the Alps as a Lämmergeier. It has been credited with a habit of scaring young animals over the cliffs by descending with a sudden rush, but its nature is cowardly, and it does not seem to attack man; yet marvellous tales have been told of its strength and daring, some of which may in part be true, though the evidence is hardly convincing. Like Neophron, it is said to carry bones up into the air, letting them fall to break them, while land-tortoises are similarly treated in North Africa, and possibly this species is responsible for the death of the poet Æschylus, on whose bare head a tortoise is alleged to have been dropped.[[134]] Gypohierax angolensis, somewhat approaching the Vulturidae, is white, with the secondaries, most of the scapulars, the tips of the primaries, and the base of the tail black; the bare skin of the sides of the face and the feet are flesh-coloured, and the beak is grey-blue. Rare in East and South Africa, though common in the West, it is generally seen on lagoons, rivers, or sea-shores, sunning itself on some elevation, or skimming the water with laboured flight in search of fish. It will attack animals and eat garbage.
Sub-fam. 2. Polyborinae.–Of the American "Carrion Hawks," Polyborus tharus is dull black, with whitish neck, back, breast, and tail, more or less barred with dusky, and broad blackish tips to the rectrices. The bare red skin of the cheeks and throat imparts a vulturine look, belied, however, by the almost gallinaceous feet. It inhabits South America from Ecuador and Guiana southwards; but thence the very similar P. cheriway ranges to Florida and Lower California, P. lutosus occurring in Guadelupe Island off the latter. The Carancho or Cáracara, as P. tharus is called, resembles in habits the "Turkey-Buzzards" (Rhinogryphus), with which it consorts, though somewhat shy and quarrelsome. Semi-gregarious, and audacious if unmolested, it passes the hot hours in the shade, and roosts in company at night; while the powerful and graceful flight, with its alternate sailing or flapping movements, though not rapid, enables it to soar in spirals to a great altitude. It walks or runs with ease. The far-reaching grating note is usually uttered with the head thrown back; the food of refuse and carrion is supplemented by young lambs or alligators, birds, frogs, reptiles, land-crabs, worms, and insects. When on a tree, bush, or cliff, the large shallow nest, often renewed yearly, is made of sticks and lined with grass, leaves, roots, wool, or scraps of any sort; but, when on the ground or in swamps, reeds and herbage are commonly utilized. The three or four eggs ranging from white with red blotches to cinnamon with a few black marks.
Ibycter, Phalcobaenus, and Senex are kindred Neotropical genera of a greenish-black colour, with a variable amount of white on the tail, lower parts, and even the wings and nape; the cheeks and throat are naked and red in the first, and orange in the second, while the cheeks only are yellow in the third. Phalcobaenus has a slight crest, P. carunculatus a fleshy orange caruncle at the base of the bill, Senex rufous thighs. Ibycter ater occurs in Amazonia, I. americanus from Guatemala and Honduras to Brazil, Phalcobaenus megalopterus from Chili to West Peru, P. carunculatus in Ecuador and New Granada, P. albigularis in Patagonia, while Senex australis is the "Johnny Rook" of the Falklands. Close allies are Milvago chimachima and M. chimango, ranging from Panama to Paraguay, and from about lat. 20° S. to Tierra del Fuego respectively; the former is brown, with creamy head, neck, tail, and under-parts, and rectrices barred with brown; the latter has the head rufous and black, the lower surface streaky-looking yellowish-brown, the tail greyer. The lores and naked orbits are pinkish.
These forms are similar in manners to Polyborus, but Milvago is more terrestrial, and chiefly frequents grassy plains; it is moreover less energetic, and has an easy and loitering though protracted flight, with a custom of uttering its whistling or mournful notes in chorus, the head being thrown back as in the Carancho. The nest of sticks, lined with grass, hair, and wool, may be on trees, in grass, or rushes, Senex preferring sea-girt cliffs; the eggs, from two to five in number, are cream-coloured, or reddish with darker markings, and vary as in Polyborus. Human beings are very rarely molested by "Carrion Hawks," though birds seem to fear them greatly.