A peculiar interest attaches to this species owing to the fact that it is the only freshwater Duck in the subfamily Fuligulinæ, in which it is classed. With the exception of the Loggerhead Duck (Tachyeres cinereus), found in the Falklands and the Magellan Straits, all the other sea-ducks of this division inhabit North and Central America; so that the Rosy-bill appears to have separated itself widely from its nearest relations geographically as well as in habits. In appearance it is a fine bird, the black plumage being frosted on the upper parts with white in a very delicate manner, while the rosy bill and large carmine caruncle and golden red iris contrast beautifully with the glossy purple head and neck. The speculum is white, the legs bright yellow. The plumage of the female is brown.
In marshy places on the pampas the Rosy-billed Duck is very abundant, and they sometimes congregate in very large flocks. They obtain their food from floating weeds in the water, and are never seen, like the Pintails and other kinds, feeding on the dry land. They rise heavily, the wings being comparatively small, and have a rapid, straight, violent flight; they are nevertheless able to perform long journeys and travel in long lines and at a considerable elevation. Their only language is a deep, hoarse, prolonged, raven-like note, uttered by the male in the love-season. The nest is made on swampy ground near the water, of dry rushes, and is, for a duck, a deep well-made structure; the eggs are oval in form, cream-coloured, and twelve in number.
[355.] ERISMATURA FERRUGINEA, Eyton.
(RUSTY LAKE-DUCK.)
Erismatura ferruginea, Scl. et Salv. Nomencl. p. 131; iid. P. Z. S. 1876, p. 404; Sclater, P. Z. S. 1872, p. 549 (Rio Negro); Burmeister, P. Z. S. 1872, p. 368 (Buenos Ayres); Durnford, Ibis, 1877, p. 42 (Chupat), p. 192 (Buenos Ayres), et 1878, p. 401 (Central Patagonia).
Description.—Above chestnut-red, whole head and neck black; wings and tail brown: beneath dirty white, sprinkled with brown; breast and flanks chestnut; bill bluish; feet brown: whole length 16·0 inches, wing 5·5, tail 3·8.
Hab. Central Peru, Chili, and Argentina.
This Lake-Duck ranges from Central Peru and the north Argentine provinces to Patagonia in the south, but is in no place a very common bird. It inhabits interior lakes and streams, living almost as much in the water as a Grebe, which in habits it resembles, remaining motionless when disturbed, but gradually sinking lower in the water, and diving, when only the head and neck are visible above the surface.