The Impennes, or Penguins, which form the eighteenth order of birds, according to the arrangement of the ‘Nomenclator,’ are a group specially characteristic of high Antarctic latitudes. Nine species of Penguins occur on the coasts of Antarctic America, but one of these only is as yet known to reach so far north as our limits.
We now come to the Crypturi or Tinamous, an order of birds commonly supposed to be Gallinaceous, and generally confounded with “Partridges” and “Pheasants” in the vernacular. They are, however, in some points of essential structure more nearly allied to the Struthiones, although they doubtless fill the same place in the economy of Neotropical Nature as the true Gallinaceous birds in other lands. The Tinamous are spread all over the Neotropical Region and number about 36 species. Eight of these occur within the Argentine Republic; and amongst them we may pick out the Martineta Tinamou (Calodromas elegans) and the three species of the genus Nothura as being specially characteristic Patagonian types.
Lastly, we come to the final order of the Neotropical Ornis in the shape of the Rheas, or the American representatives of the Ostrich-type of bird-life. The Rhea is, above all other birds, a most characteristic representative of the Avifauna of the Patagonian subregion. It is true that it ranges far north throughout the campos of Inner Brazil, where the outlying members have become developed into an almost distinct species or subspecies, Rhea americana macrorhyncha. But south of the Rio Negro of Patagonia another very distinct type of Rhea, almost subgenerically different, is met with and extends thence to the Straits of Magellan. Rhea has also been lately ascertained to occur on the western side of the Andes in the Chilian province of Tarapaco; so that this fine form of bird-life is diffused nearly over the entire Patagonian subregion, and is well entitled to be termed one of the most characteristic features of the Patagonian Avifauna.
In conclusion, therefore, we may sum up our present knowledge of the Argentine Avifauna somewhat as follows:—
The Argentine Avifauna comprises 434 species of birds, referable to 54 families and genera.
All the twenty Orders of the Neotropical Avifauna have representatives within its boundaries, except the Opisthocomi or Hoatzins, which are restricted to the Amazonian subregion.
The most numerous families of the Argentine Avifauna are, among the Passeres, the Finches with 46 species, the Tyrants with 63 species, and the Wood-hewers with 46 species. Among the remaining Orders, the Diurnal Birds of Prey with 19 species, the Waterfowl with 22 species, the Rails with 13 species, the Snipes with 15 species, and the Tinamous with 8 species, are likewise well represented.
Genera characteristic and proportionately numerous in species in the Argentine Avifauna are Poospiza and Phrygilus among the Finches, Tænioptera and Cnipolegus among the Tyrants, Synallaxis among the Wood-hewers, Fulica among the Rails, and Nothura among the Tinamous. Less numerous in species, but highly characteristic forms of the Argentine Ornis, are Thinocorus, Rhynchotis, and Rhea.
The following ten genera, mostly monotypic, are, so far as we know at present, restricted to the limits of the Argentine Avifauna or its immediate confines:—Donacospiza and Saltatricula (Fringillidæ); Coryphistera, Anumbius, Limnornis, and Drymornis (Dendrocolaptidæ); Rhinocrypta, with two species (Pteroptochidæ); Spiziapteryx (Falconidæ); Chunga (Cariamidæ); and Calodromas (Tinamidæ).
[1] Cf. Sclater, Journ. Linn. Soc., Zool. ii. p. 143 (1857).