Anumbius acuticaudatus, Burm. La-Plata Reise, ii. p. 467 (Paraná, Mendoza); Scl. et Salv. Nomencl. p. 64; Hudson, P. Z. S. 1874, p. 159 (Buenos Ayres); Durnford, Ibis, 1877, p. 181 (Buenos Ayres); White, P. Z. S. 1882, p. 612 (Buenos Ayres); Barrows, Bull. Nutt. Orn. Cl. viii. p. 211 (Entrerios).
Description.—Above earthy brown, forehead chestnut, superciliaries white, head, neck, and back marked with black striations; primaries blackish, secondaries pale chestnut-brown; tail black, all the feathers except the middle pair broadly tipped with cream-colour; beneath pale ochraceous brown, white on the throat, the white bordered on each side by numerous small black spots; bill and feet pale horn-colour: whole length 8·3 inches, wing 3·6, tail 3·7. Female similar.
Hab. Argentina, Uruguay, Paraguay.
This is a common and very well-known species throughout the Argentine country and Patagonia, also in Uruguay and Paraguay, and is variously called Espinero (Thorn-bird), Tiru-riru, in imitation of its note, and Añumbi (the Guarani name); but its best known name is Leñatero, or “Firewood-Gatherer,” from the quantity of sticks which it collects for building-purposes.
The Firewood-Gatherer is a resident in Argentina, and pairs for life. Sometimes the young birds remain with their parents for a period of three or four months, all the family going about and feeding in company, and roosting together in the old nest. The nest and the tree where it is placed are a favourite resort all the year round. Here the birds sit perched a great deal, and repeat at intervals a song or call, composed of four or five loud ticking chirps, followed by a long trilling note. They feed exclusively on the ground, where they creep about, carrying the body horizontally and intently searching for insects. When disturbed, they hurry to their usual refuge, rapidly beating their very feeble wings, and expanding the broad acuminated tail like a fan. When the male and female meet at their nest, after a brief separation, they sing their notes in concert, as if rejoicing over their safe reunion; but they seldom separate, and Azara says that when one incubates, the other sits at the entrance to the nest, and that when one returns to the nest with food for the young the other accompanies it, though it has found nothing to carry.
To build, the Añumbi makes choice of an isolated tree in an open situation, and prefers a dwarf tree with very scanty foliage; for small projecting twigs and leaves hinder the worker when carrying up sticks. This is a most laborious operation, as the sticks are large and the bird’s flight is feeble. If the tree is to its liking, it matters not how much exposed to the winds it may be, or how close to a human habitation, for the bird is utterly unconcerned by the presence of man. I have frequently seen a nest in a shade or ornamental tree within ten yards of the main entrance to a house; and I have also seen several on the tall upright stakes of a horse-corral, and the birds working quietly, with a herd of half-wild horses rushing round the enclosure beneath them, pursued by the men with lassos. The bird uses large sticks for building, and drops a great many; frequently as much fallen material as would fill a barrow lies under the tree. The fallen stick is not picked up again, as the bird could not rise vertically with its load, and is not intelligent enough, I suppose, to recover the fallen stick, and to carry it away thirty yards from the tree and then rise obliquely. It consequently goes far afield in quest of a fresh one, and having got one to its liking, carefully takes it up exactly by the middle, and, carrying it like a balancing-pole, returns to the nest, where, if one end happens to hit against a projecting twig, it drops like the first. The bird is not discouraged, but, after a brief interview with its mate, flies cheerfully away to gather more wood.
Durnford writes wonderingly of the partiality for building in poplar trees shown by this bird in Buenos Ayres, and says that in a tall tree the nest is sometimes placed sixty or seventy feet above the ground, and that the bird almost invariably rises with a stick at such a distance from the tree as to be able just to make the nest, but that sometimes failing it alights further down, and then climbs up the twigs with its stick. He attributes the choice of the tall poplar to ambition; but the Añumbi has really a much simpler and lowlier motive. In the rich Buenos Ayres soil all trees have a superabundance of foliage, and in the slim poplar alone can the nest be placed where the bird can reach it laden with building-material, without coming in contact with long projecting twigs.
The nest of the Añumbi is about two feet in depth, and from ten to twelve inches in diameter, and rests in an oblique position amongst the branches. The entrance is at the top, and a crooked or spiral passage-way leads down to the lower extremity, where the breeding-chamber is situated; this is lined with wool and soft grass, and five white eggs are laid, varying considerably in form, some being much more sharply pointed than others.
The nest, being so secure and comfortable an abode, is greatly coveted by several other species of birds to breed in; but on this subject I have already spoken in the account of the genus Molothrus. When deprived of their nest, the birds immediately set to work to make a new one; but often enough, without being ejected from the first they build a second nest, sometimes demolishing the first work to use the materials. I watched one pair make three nests before laying; another pair made two nests, and after the second was completed they returned to the first and there elected to remain. Two or three nests are sometimes seen on one tree, and Azara says he has seen as many as six. Mr. Barrows observed the bird at Concepcion, where it is very common, and writes that in that district the nest is sometimes four feet long with an average diameter of two feet, and that the same nest in some cases is used for several seasons successively; also that several nests are sometimes joined together and all occupied at the same time.