Of the Birds of Prey of the Argentine Republic, Diurnal and Nocturnal, it is not necessary to say much; both of these orders are rather in excess as regards the average number of species, the Accipitres especially so. The wide open pampas offer a fine field for Kites and Buzzards and their kind, and they are as numerous in individuals as in species in such favoured haunts.
In the next order, Steganopodes, the Argentine Ornis seems to be very deficient. Out of the five families of this group which occur in the Neotropical Region, one only is yet known to us to be represented in the Argentine Ornis, and that by a single species. But when the sea-birds of the Argentine coast-land come to be better known, there is no doubt that several additions will be made to the list.
The next following order, Herodiones, is of much more importance in Argentine Ornithology, not less than 19 species of this group being already known to exist within our limits, out of a total of 44 Neotropical species. And amongst these we can pick out the little Variegated Bittern (Ardetta involucris) and the four species of Ibises as being highly characteristic members of the Argentine Ornis.
The tenth order, that of Anseres, or Waterfowl, commonly so-called, is also largely in excess as regards the number of species. Out of a total of 64 Anseres belonging to the Neotropical Regions, 23 are met with in the Argentine Republic. Moreover, the greater number of these are exclusively Antarctic species, restricted to the Patagonian Subregion. Amongst them we may specially call attention to the Black-necked Swan (Cygnus nigricollis), the Chiloe Wigeon (Mareca sibilatrix), and the Rosy-billed Duck (Metopiana peposaca) as highly characteristic and ornamental species.
Proceeding to the next order, that of the Pigeons (Columbæ), we find the number of Argentine species to be slightly below the average. Several fine Pigeons and Doves are well-known inhabitants of the Republic, but the Columbine order is not a prominent one within our limits.
The Gallinaceous birds of the Neotropical Region are about ninety in number, the greater part of these belonging to the Curassows, Cracidæ, a family specially adapted for habitation in the extensive forests of the New World. Four species of Cracidæ have been met with in the forest-region of Northern Argentina; but the Gallinaceous group as a whole must be held to be deficient in this part of South America, the place in Nature which these birds fill in other regions being occupied here by the more lowly organized Tinamous, of which we shall speak further on.
The Geranomorphæ of the Argentine Republic are much in excess as regards the number of species. This arises mainly from the abundant supply of Rails and Crakes which Nature has provided for the more swampy districts of the pampas, and to the presence of no less than three distinct species of Coots (Fulica), which appear to be generally abundant on the lakes and pools. Nor must we forget to mention as of special interest the two Cariamas which belong to this order, and which are the only representatives of a family of very peculiar structure. One of the two Cariamas is, so far as we know, absolutely confined to the Northern provinces of the Argentine Republic; the second is a bird of the campos of Southern Brazil, which only just comes within our limits.
The Snipes and Plovers and their allies, constituting the Order Limicolæ, are again in excess in the Argentine Avifauna, not less than 25 out of a known total of 73 Neotropical species having been already met with within our limits. A large proportion, however, of these birds are merely winter visitors, and breed only in the far north. On the other hand, the Slender-billed Plover (Oreophilus ruficollis) and the Winter Plover (Eudromias modesta) are species highly characteristic of the Patagonian subregion, and come to the neighbourhood of Buenos Ayres from a contrary direction. Another especially characteristic Patagonian family of this order is the Thinocoridæ or Seed-Snipes, of which two species occur within our limits.
Of the Gaviæ, or Gulls and Terns, of the Argentine Republic, nine species are already known out of a total of 53 Neotropical members of the group, and additions no doubt will be made to the list when the coast-birds of La Plata come to be better known.
The seventeenth order of Birds, Pygopodes, is represented in the Argentine Ornis by five species of Grebes. Two of these are widely diffused over all America, the remaining three are Antarctic species belonging to the Patagonian subregion. As only nine species of this groups are known to occur in the whole Neotropical Region, the Pygopodes are highly in excess in the Argentine Avifauna.