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Show 142 ZOOLOGY OF THE VOYAGE OF TilE BEAGLE. The whole of the plumage deep leaden-grey; the upper and under tail coverts being lightest; bill red at the base, black at the t1p; feet black. Habitat, Galapagos Archipelago (October). Tht.s speci·e s of gu 11 has many characters in c.o mmon with the Larus lu£dm' a·t o- 1.Jtyncltus of King, from the continent of S. Amenca; but may at once be . Istm-guished from it by the general extreme duskiness of its plum~ge, feet, tar.si, and bill; and by the more elongated form of the l~tt~r. M.y speci~en was killed. at James Island. I observed nothing particular m Its habits. It IS the only spec1es of gull frequenting this Archipelago. 2. LAnus H.lEMATORHYNCHUS. King. Larus hmmatorhynchus, King, Zool. Journ. iv. 103. -----~-Jard. 4' Selb. Ill. Orn. p. 1 OG. This bird was killed at Port St. Julian on the coast of Patagonia. (when fresh killed) of a pale" arterial blood red," legs "vermilion red." 3. LARUS DOMINICANUS. Lic/tt. Larue dominicanus, Licltt. Cat. 82. sp. 846. Grande Mouette, Azara, No. 409. Beak This gull abounds in flocks on the Pampas, sometimes ~ven as mu~h as fifty and sixty miles inland. Near Buenos Ayres, and at Bahia. Blanca, It .attends the slaughtering-houses, and feeds, together with the Polybon and Cathartes, on the garbage and offal. The noise which it utters is very like that of the common English gull (Larzts canus, Linn.) XEMA (CHROICOCEPHALus) CIRROCEPHALUM. G. R. G1'ay. Larus cirrocephalus, Vieill. Nov. Diet. d'Histoiro, 21. p. 502. Larus maculipennis, Licltt. Cat. 83. sp. 855. Larus gla.ucodes, Mcyen, Nov . .Act. 1839, p. 115. pl. 24. Mouettc cendree, Azara, No. 410. This species so closely resembles the Xema ridibundum, Boie, that Mr. Gould observes, he should have hardly ventured to have characterized it as distinct; but as M. Vieillot and Meyen have deemed this necessary, he adopts their view. I have compared a suite of specimens, which I procured from the Rio Plata, the coast of Patagonia, and the Straits of Magellan, with several specimens of the Xema 1'idibundum; the only difference which appears to me constant, is that the primaries of the X. cirrocepltalum, in the adult winter plumage, both of male and female, are tipped with a white spot (a character common to some other species), whereas in the X.1·idibttndttm the points are black. The beak of the latter species, DIRDS. 143 especially the lower mandible, is also a little Jess strong, or high in proportion to its length. In the immature stage, I could perceive no difference whatever in the plumage of these birds. The proportional quantity of black and white in the primaries, given by Meyen as the essential character, varies in the different states of plumage. The specimens described by this author were procured from Chile.• The soles of the feet of my specimens were coloured, deep "reddish orange," and the bill dull "arterial blood-red" of Werner's nomenclature. In the plains south of Buenos Ayres I saw some of these birds far inland, and I was told that they bred in the marshes. It is well known that the blackheaded gull ( Xema ridibundum ), which we have seen comes so near the X. cirrocepltalum, frequents the inland marshes to breed. It appears to me a very interesting circumstance thus to find birds of two closely allied species preserving the same peculiarities of habits in Europe and in the wide plains of S. America. Near Buenos Ayres this gull as well as the L. dominicanus sometimes attends the slaughter-houses to pick up bits of meat. RnYNCHOPS NIGRA. Linn. I saw this bird both on the East and West coast of South America, between latitudes :30° and 45°. It frequents either fresh or salt water. Near Maldonado (in May), on the borders of a lake, which had been nearly drained, and which in consequence swarmed with small fry, I watched many of these birds flying backwards and forwards for hours together, close to its surface. They kept their bills wide open, and with the lower mandible half buried in the water. Thus skimming the surface, generally in small flocks, they ploughed it in their course ; the water was quite smooth, and it formed a most curious spectacle, to behold a flock, each bird leaving its narrow wake on the mirror-like surface. In their flight they often twisted about with extreme rapidity, and so dexterously managed, that they ploughed up small fish with their projecting lower mandibles, and secured them with the upper half of their scissor-like bills. This fact I repeatedly witnessed, as, like swallows, they continued to fly backwards and forwards, close before me. Occasionally, when leaving the surface of the water, their flight was wild, irregular, and rapid; they then also uttered loud harsh cries. When these birds were seen fishing, it was obvious that the length of the primary feathers was quite necessary in order to keep their wings dry. When thus employed, their forms resembled the symbol, by which many artists represent marine birds. The tail is much used in steering their irregular course. These birds are common far inland, along the course of the Rio Parana; and "' The naturalists in Lutke's voyage, vol. iii. p. 25.5, seem to consider a gull, which they obtained a.t Concepcion, as tho Larus Franklinii of North America.. |
