Hab. Coasts of S.E. Brazil, Argentina, and Chili.
This beautiful Tern, peculiar for its white head in the adult dress, was observed by Durnford on Flores Island in the Rio de la Plata, and in other places on the coast of the Argentine Republic. One was obtained near Punta Lara, in October 1876; and many more since by Mr. E. Gibson, Commander MacFarlane, and others.
[414.] STERNA HIRUNDINACEA, Less.
(CASSIN’S TERN.)
Sterna hirundinacea, Saund. P. Z. S. 1876, p. 647; Durnford, Ibis, 1878, p. 404 (Centr. Patagonia). Sterna cassini, Scl. et Salv. Nomencl. p. 147; iid. P. Z. S. 1871, p. 570; Durnford, Ibis, 1877, p. 201 (Buenos Ayres).
Description.—Head and nape black; mantle and wings grey, darker on the quills; rump white; tail pearl-white, darker on the outer streamers; underparts greyish white; bill blood-red; feet orange-crimson: whole length 15·0 inches, wing 11·5. Young: streaked on the head and mottled on the upper parts with blackish.
Hab. Patagonia, Chili, Peru, Argentina, Brazil, and Falkland Islands, up to Rio.
This is a black-headed Tern with a blood-red bill, which is found abundantly on the coast of Patagonia, and extends up the Atlantic coast to Rio. It was noticed by Durnford near Buenos Ayres, and found breeding by the same excellent observer at Tombo Point, about sixty miles to the south of Chupat, in December 1877. He tells us:—
“I was prepared when I visited this place in December to see a considerable quantity of birds; but the number that met my eyes fairly staggered me. Their nests covered an area about 150 yards square. Allowing three nests and five eggs for every square yard (a very moderate computation, it being difficult to walk without treading on the eggs), we arrive at the extraordinary number of 67,500 nests, 135,000 birds, and 112,500 eggs; and, wonderful as these figures may appear, I feel sure that I have rather understated than overstated the numbers. The nests were mere hollows in the fine gravel or shingle, and contained one, two, and sometimes three eggs. The latter generally have the appearance of the eggs of the Sandwich Tern, though of course smaller; and out of many hundreds I did not see two alike.”