[Plate VI. Fig. 2.]
| Fig. | 1. | MOLOTHRUS | BADIUS. ad. |
| " | 2. | " | RUFO-AXILLARIS. pull. |
Molothrus rufoaxillaris, Scl. et Salv. Nomencl. p. 37; Hudson, P. Z. S. 1874, p. 161 ([Buenos] Ayres); Durnford, Ibis, 1877, p. 174 (Buenos Ayres); White, P. Z. S. 1882, p. 601 (Catamarca); Barrows, Bull. Nutt. Orn. Cl. viii. p. 134 (Entrerios); Scl. Cat. B. xi. p. 338.
Description.—Silky black, washed with purple; wings and tail with a slight greenish gloss; a chestnut spot on the axillaries; bill and feet black: whole length 8·0 inches, wing 4·5, tail 3·3. Female similar, but somewhat smaller.
Hab. Argentina and Uruguay.
This bird has no vulgar name, not being distinguished from the Common Cow-bird by the country people. The English name of Screaming Cow-bird, which I have bestowed on it, will, I think, commend itself as appropriate to those who observe this bird, for they will always and at any distance be able to distinguish it from the species it resembles so nearly by listening to its impetuous screaming notes, so unlike anything in the language of the Common Cow-bird.
The Screaming Cow-bird is larger than the allied species. The female is less than the male in size, but in colour they are alike, the entire plumage being deep blue-black, glossy, and with purple reflections; and under the wing at the joint there is a small rufous spot. The beak is very stout, the plumage loose, and with a strong, musky smell; the œsophagus remarkably wide.
It is far less common than the other species of Molothrus, but is not rare, and ranges south to the Buenos-Ayrean pampas, where a few individuals are usually found in every large plantation; and, like the M. badius, it remains with us the whole year. It is not strictly gregarious, but in winter goes in parties, never exceeding five or six individuals, and in the breeding-season in pairs. One of its most noteworthy traits is an exaggerated hurry and bustle thrown into all its movements. When passing from one branch to another, it goes by a series of violent jerks, smiting its wings loudly together; and when a party of them return from the fields they rush wildly and loudly screaming to the trees, as if pursued by a bird of prey. They are not singing-birds; but the male sometimes, though rarely, attempts a song, and utters, with considerable effort, a series of chattering unmelodious notes. The chirp with which he invites his mate to fly has the sound of a loud and smartly-given kiss. His warning or alarm-note when approached in the breeding-season has a soft and pleasing sound; it is, curiously enough, his only mellow expression. But his most common and remarkable vocal performance is a cry beginning with a hollow-sounding internal note, and swelling into a sharp metallic ring; this is uttered with tail and wings spread and depressed, the whole plumage raised like that of a strutting turkey-cock, whilst the bird hops briskly up and down on its perch as if dancing. From its puffed-out appearance, and from the peculiar character of the sound it emits, I believe that, like the Pigeon and some other species, it has the faculty of filling its crop with air, to use it as a “chamber of resonance.” The note I have described is quickly and invariably followed by a scream, harsh and impetuous, uttered by the female, though both notes always sound as if proceeding from one bird. When on the wing the birds all scream together in concert.
The food of this species is chiefly minute seeds and tender buds; they also swallow large caterpillars and spiders, but do not, like their congeners, eat hard insects.