Fig. 300.—The Brazilian Caracaras (Polyborus brasiliensis).
Having confidence in its own strength, the Caracara frequently pursues other birds, especially Vultures and Gulls, which it forces to disgorge their food. It will even engage in sanguinary conflicts with its own species for the possession of prey. Contrary to the habit of most birds in a state of freedom, it remains constantly paired, without, however, having more than one or two broods a year. The Caracara lays two eggs; the nest is generally placed on the ground among brushwood.
Besides the four species we have mentioned there is also the Caracara funebris, thus named on account of its plumage, which is almost entirely of a black hue. This bird is still more of a plunderer than the preceding species, and is a native of the shores of Tierra del Fuego, the Falkland Isles, Van Diemen's Land, New Zealand, &c.
Vultures.
The Vultures (Vulturidæ) form a well-marked genus, which is readily distinguished from the Falcons by the following characteristics:—A beak almost entirely straight, and curved only at its extremity; the head and neck generally devoid of feathers; small and staring eyes; head small; tarsi generally bare; toes short and slightly curved; weak claws; and wings very long. They are also distinguished from holding themselves in a horizontal position, whether walking or at rest; whereas the Falcons stand erect, and present a noble bearing. Vultures probably adopt their attitude on account of the length of their wings, which even in a stooping position sweep the ground, and would drag much more but for this precaution. Lastly, they are specially characterised by their partiality for putrefied flesh, which forms their almost exclusive nutriment, as it is only occasionally they attack living prey.
When a Vulture has glutted itself, its crop, swelled by the food which it has devoured, forms a voluminous projection in front of the neck; a fetid humour oozes from its nostrils, and it remains sunk in a state of stupid torpor until the food is digested.
They fly heavily, but mount aloft to great altitudes. Their powers of vision are extraordinary. Should a carcass be left on the plain, they immediately see it and drop down, turning over and over in their hurry to partake of the anticipated banquet. It has been supposed by some that their olfactory organs are so acute as to smell, at great distances, the emanations which escape from bodies in a state of decomposition, and thus to account for their prompt arrival. Latterly, however, certain observers have opposed this theory: according to their ideas the Vulture tribe owe this wonderful facility to their sight, not to scent. This reason however, has not as yet been rendered altogether clear. We therefore think it prudent to abstain from giving an absolute judgment on the point, and will content ourselves by admitting that both sight and smell concur in producing the result: these two senses may either exercise an equal power, or one of them may predominate over the other.
The Vulture family exhale a tainted odour, which is owing to the peculiar nature of their nutriment; it is, therefore, impossible for their flesh to be in any way utilised as food. This family comprises four principal genera: the Griffons (Gypaëtos, Storr), the Sarcoramphi (Duméril), the Cathartes (Cuv.; Gallinazos, Vieill.), and the Common Vultures (Percnopterus, Cuv.; Neophron, Sav.).
The Griffons, or Vulture Eagles (Vultur fulvus, Bennett), form, as their name indicates, an intermediate genus between the Eagles and the Vultures. Although they have small and goggle eyes, not very strong talons, and a projecting crop during the digestion of their meals, they are allied to the Eagles in virtue of their feathered tarsi, as well as by their head and neck; they also show a preference for living prey, which they attack with readiness. We will complete their portrait by stating that they have a very strong beak, enlarged towards the point.