A third species, the large-billed rhea (Rhea macrorhyncha), has been discovered. These birds in vast numbers inhabit the wide-extended plains, and afford a welcome addition to the food of their roving inhabitants.
Caracara Polyborus.
The largest caracara—Polyborus Braziliensis—ranges the grassy savannahs of La Plata. Across the desert, between the rivers Negro and Colorado, numbers constantly attend the line of road, to devour the carcasses of the exhausted animals which chance to perish from fatigue and thirst. It also attends the estancias and slaughtering-houses, accompanied by its smaller relative, the chimango. “When an animal dies on the plain the gallinaso commences the feast, and then the two species of polyborus pick the bones clean,” says Darwin. These birds, although thus commonly feeding together, are far from being friends. When the caracara is quietly seated on the branch of a tree or on the ground, the chimango often continues for a long time flying backwards and forwards, up and down, in a semicircle, trying each time at the bottom of the curve to strike its larger relative. The caracara takes little notice, except by bobbing its head. The caracaras are crafty, and steal numbers of eggs; they also attempt, together with the chimango, to pick off the scabs from the sore backs of horses and mules. These false eagles rarely kill any living bird or animal; and their vulture-like, necrophagous habits are very evident to any one who has fallen asleep on the desolate plains; for, when he awakes, he will see on each surrounding hillock one of these birds patiently watching him with an evil eye. If a party of men go out hunting with dogs and horses, they will be accompanied during the day by several of these attendants.
The flight of the caracara is heavy and slow, and it is generally an inactive, tame, and cowardly bird. It destroys young lambs, by tearing the umbilical cord; and it pursues the gallinaso till that bird is compelled to vomit up the carrion it may have recently gorged. It is said, also, that several caracaras will unite in chase of large birds, even such as herons.
The chimango is tame and fearless; and when an animal is killed a number soon collect, and patiently wait, standing on the ground on all sides. Darwin describes seeing one pounce on a dog which was lying asleep close to one of a party of sportsmen. They had difficulty in preventing their canine companion from being seized before their eyes.
It will frequently wait, as does the caracara, at the mouth of a rabbit-hole, and seize on the animal when it comes out. It is also very mischievous and inquisitive. It will pick up almost anything from the ground: a large black glazed hat was carried nearly a mile, as were a pair of heavy bolas. On another occasion a small Kater’s compass in a red morocco case was carried off, and never recovered. These birds are, moreover, quarrelsome and very passionate, tearing up the grass with their bills in their rage. They are noisy, too, uttering several harsh cries—one of them like that of the English rook.
Owls of the Pampas (Athene Cuniculaeia).
The traveller across the Pampas will see a number of little owls—generally seated in pairs, during the evening, on the hillocks near the burrows of the bizcacha, occasionally uttering their strange wild hoots to each other. If disturbed, they either run into the holes of their friends, in which they have their abode; or, uttering a shrill, harsh cry, they move with a remarkably undulatory flight to a short distance, and then turning round, steadily gaze at their pursuer.
The Pampas Cuckoo (Molothrus Niger).
Among the birds of numerous kinds which abound on the plains, there are several worthy of notice. One is remarkable from its habits.