According to Mr. Gibson, who has observed their breeding-habits, they begin to nest in July--just after the winter solstice. The nest is always placed among thick rushes growing in deep water, and the Swan invariably swims to and from her nest. It is built up from the bottom of the swamp, sometimes through four or five feet of water, and rises a foot and a half above the surface. The top of the nest measures about two feet across, with a slight hollow for the eggs, which are cream-coloured and have a smooth glossy shell. The number varies from three to five, and on one occasion six were found. Mr. Gibson has seen the parent bird swimming from the nest with the young on her back.
Our figure of this species (Plate XVIII.) is taken from the specimen now living in the Zoological Society's Gardens.
+Cygnus coscoroba+, _Burm. La-Plata Reise_, ii. p. 512 (Paraná); _Scl. et Salv. Nomencl._ p. 129; _iid. P. Z. S._ 1876, p. 371; _Durnford, Ibis_, 1877, p. 191 (Buenos Ayres), et 1878, p. 400 (Centr. Patagonia); _Gibson, Ibis_, 1880, p. 36 (Buenos Ayres). +Coscoroba Candida+, _Reichenb. Nat. Syst._ p. x.
_Description._--White; tips of the primaries black; bill coral-red; feet dull red: whole length 40·0 inches, wing 17·5, tail 5·8. _Female_ similar.
_Hab._ Patagonia, Chili, Argentina, and Paraguay.
This Swan is considerably smaller than the black-necked species, and also inferior in beauty on account of its shorter neck. It is, nevertheless, a very handsome bird, being entirely of a pure white colour except the tips of the primaries, which are black. The beak and legs are bright rosy red. In its habits, language, and flight it also differs much from _Cygnus nigricollis_, and the country people call it _Ganso_ (Goose), probably on account of its goose-like habit of sometimes feeding away from the water, or because its flesh has the flavour of Wild Goose. As a rule they go in small parties of five or six individuals, but sometimes flocks numbering two or three hundred are seen in the cold season. Their migrations are very irregular, and sometimes they are excessively abundant in a district one year and absent from it the next. When disturbed they utter a loud musical trumpeting cry, in three notes, the last with a falling inflection; and their wings being much longer proportionately than in the black-necked species, they rise with greater ease and have a much freer and an almost soundless flight.