INTRODUCTION ix 
of a wandering disposition, like the European 
Crossbills, the Waxwing, and the Short-eared Owl. 
They have the gipsy habit or the Columbus-like 
spirit of the poet’s Stork, who goes forth to explore 
heavens not his own and worlds unknown before. 
Finally, we have a multitude of species, both 
resident and migratory, belonging to families that 
have a world-wide distribution. Among these are 
the Thrushes, Wrens, Pipits, Swallows, Finches, 
Crows, Swifts, Goatsuckers, Woodpeckers, Cuckoos, 
Owls, Hawks, Vultures, Herons, Storks, Plover, 
Snipe, Duck, Rails, Guils, Cormorants and Grebes. 
These universally distributed families are always 
more numerous in the temperate zones than in the 
tropics in relation to the entire number of species. 
Thus they are relatively more numerous in the 
temperate district of La Plata than in the Brazilian 
Forest region. 
Undoubtedly South America is richer in bird life 
than any other region of equal extent. The species 
number considerably over 2,000, and one half or 
something over a half belong to a single order— 
Passeres, or Perchers. Half of these again are in- 
cluded in the Sub-Order Oscines, or birds with a 
developed vocal organ—the song birds. We see thus 
how rich this region is in bird life in which the 
songsters alone equal in number, if they do not 
exceed, all the species of birds in Europe together. 
About a quarter of the entire number of South 
American species inhabit Argentina, and about half 
that number are found in the Plata district, which 
